• 03/09/11: Shuttle Discovery glides to final landing
• 03/09/11: Discovery astronauts prepare for landing
• 03/08/11: Flight director optimistic about weather, Discovery landing Wednesday
• 03/08/11: Shuttle crew reflects on the legacy of Discovery
• 03/08/11: Discovery crew enjoys 'live' wakeup call; packs for re-entry
• 03/07/11: Discovery undocks from space station
• 03/06/11: Farewell ceremony; hatch closure
• 03/06/11: Shuttle crew bids farewell; prepares for undocking
• 03/05/11: Astronauts focus on space station maintenance, cargo transfers
• 03/04/11: Astronauts focus on module unpacking, equipment transfers
• 03/03/11: Shuttle flight extended a second day; Obama calls astronauts
• 03/02/11: Drew, Bowen carry out second spacewalk
• 03/02/11: Astronauts gear up for second spacewalk
• 03/01/11: Proposed Soyuz fly around of space station ruled out
• 03/01/11: New module attached to space station
• 02/28/11: Shuttle mission extended one day
• 02/28/11: Spacewalk complete; all objectives accomplished
• 02/28/11: Astronauts suit up for spacewalk
• 02/27/11: Astronauts busy with robotics, equipment transfers
• 02/26/11: Shuttle Discovery docks with space station
• 02/25/11: NASA managers assess foam debris; preliminary analysis shows no concern
• 02/25/11: Kopra calls Discovery crewmates; wing inspections underway
• 02/24/11: Shuttle Discovery rockets into orbit
• 02/24/11: European cargo ship docks with space station
• 02/24/11: Shuttle fueling; hydrogen vent line working normally
• 02/22/11: NASA managers 'go' for shuttle Discovery's final launch
• 02/22/11: Shuttle countdown on track for Thursday launch
• 02/22/11: STS-133 mission preview (updated)
• 02/21/11: Countdown begins for Thursday shuttle launch
• 02/02/11: Discovery crew flies to Florida to prep for Thursday launch
• 02/18/11: NASA clears shuttle Discovery for Feb. 24 launch
• 02/11/11: Soyuz fly-around considered
• 01/31/11: Shuttle Discovery returns to launch pad
• 01/19/11: Bowen replaces Kopra on Discovery crew
• 01/15/11: Discovery astronaut Tim Kopra injured in bike accident
• 01/13/11: NASA sets target launch dates for next two shuttle flights
• 01/11/11: NASA zeroes in on root cause of shuttle tank cracks
• 01/10/11: NASA orders 'radius block' stiffeners for all external tank stringers
• 01/06/11: NASA rules out early February launch for shuttle Discovery
• 01/03/11: Engineers consider beefing up all external tank 'stringers'
• 12/30/10: Managers defer decision on additional stringer modifications
• 12/30/10: Inspections reveal four more cracks in shuttle tank
• 12/17/10: Shuttle tanking test; instrumentation worked well
• 12/16/10: Shuttle Discovery set for fueling test
• 12/13/10: Shuttle fueling test on tap Friday, weather permitting
• 12/03/10: Shuttle launch delayed to at least Feb. 3
• 12/02/10: 'Root cause' of shuttle tank cracks still not known; fueling test expected
• 11/24/10: Launch delayed to no earlier than Dec. 17
• 11/17/10: Tank repairs proceed amid work to develop 'flight rationale'
• 11/15/10: Fourth crack found in shuttle tank
• 11/12/10: Second cracked stringer found on Discovery's external tank
• 11/11/10: Vent line disassembled; foam repair plan refined
• 11/10/10: Underlying crack found in shuttle tank; repair options assessed
• 11/09/10: Shuttle vent line, quick-disconnect inspections begin
• 11/08/10: Update: Engineers gear up for shuttle troubleshooting
• 11/05/10: Engineers hopeful Discovery leak, foam damage can be fixed in time for 11/30 launch try
• 11/05/10: Launch scrub; hydrogen leak detected; foam cracks
• 11/04/10: Shuttle launch delayed to Friday; bad weather
• 11/03/10: Shuttle Discovery cleared for Thursday launch, weather permitting
• 11/03/10: NASA managers await engineering review to decide shuttle launch strategy
• 11/02/10: Launch delayed 24 hours by engine controller glitch
• 11/01/10: Discovery in good shape for launch; forecasters monitor weather
• 11/01/11: STS-133 mission preview
• 10/31/10: Engineers complete shuttle repairs, prepare to start countdown
• 10/30/10: Launch delayed to Wednesday by leaking OMS pod fittings
• 10/29/10: NASA managers optimistic about shuttle repair work, Tuesday launch
• 10/29/10: Start of countdown delayed 24 hours; launch off until at least Tuesday
• 10/29/10: Engineers troubleshoot nitrogen, helium leaks in shuttle rocket pod
• 10/28/10: Discovery astronauts fly to Florida to prepare for Monday launch
• 10/25/10: Discovery cleared for Nov. 1 launch
• 10/23/10: Seals replaced in shuttle fuel line flange
• 10/21/10: NASA managers optimistic seal replacement will fix shuttle leak
• 10/19/10: NASA managers order seal replacement
• 10/18/10: Engineers troubleshoot small maneuvering system fuel leak aboard shuttle Discovery
• 10/15/10: Discovery astronauts strap in for practice countdown
• 09/20/10: Shuttle Discovery moved to launch pad for final flight
• 09/11/10: Shuttle Discovery bolted to external tank
• 09/10/10: Engineers troubleshoot shuttle/external tank attachment problem
• 09/09/10: Shuttle Discovery moved to VAB
• 09/03/10: Follow-on spacewalk tasks deferred to November shuttle flight
• 07/01/10: Shuttle target dates officially reset for Nov. 1 and Feb. 26
• 05/26/10: Shuttle Atlantis returns to Earth

CBS NEWS Coverage of Breaking Space News

12:15 PM, 03/09/11 Update: Shuttle Discovery glides to final landing

By WILLIAM HARWOOD
CBS News

KENNEDY SPACE CENTER, FL--Enduring the heat of re-entry one last time, the shuttle Discovery dropped out of orbit and returned to Earth Wednesday to wrap up a near-flawless 39th and final mission, a milestone marking the beginning of the end for NASA's winged rocketships.

After firing its twin braking rockets for a computer-controlled descent halfway around the planet, commander Steven Lindsey took over manual control and guided Discovery through a 250-degree left turn to line up on runway 15.

Pilot Eric Boe then deployed the ship's landing gear and the 204,000-pound shuttle swooped to a tire-smoking touchdown on runway 15 at 11:57:17 a.m. EST (GMT-5).

Lindsey had no problems with a stiff 25-knot headwind and a few moments later, NASA's oldest surviving space shuttle rolled to a halt, wrapping up a career spanning some 5,750 orbits, 148 million miles and 365 days in space during 39 missions since its maiden launch in August 1984.

"And Houston, Discovery, for the final time, wheels stopped," Lindsey radioed flight controllers in Houston.

"Discovery, Houston, great job by you and your crew," replied astronaut Charles Hobaugh in mission control. "That was a great landing in tough conditions and it was an awesome docked mission you all had. You were able to take Discovery up to a full 365 days of actual time on orbit. I think you'd call that a fleet leader and a leader of any manned vehicle for time in orbit. So job well done."

With only two more missions left on NASA's shuttle manifest -- a flight by Endeavour in April and a final voyage by Atlantis in late June -- Discovery's landing marked the beginning of the end for the world's most complex -- and expensive to operate -- manned rocket.

"We're seeing a program come to a close here and to see these shuttles, these beautiful, magnificent flying machines end their service life is obviously a little bit sad for us," Barratt said earlier this week.

"But it is about time, they've lived a very long time, they've had a fabulous success record, they've built this magnificent space station, they've given us lots of science and a tremendous amount of experience of just how to operate in space. More than anything, we look forward to seeing them retire with dignity and bringing on the next line of spaceships."

Lindsey, Boe, Barratt and their crewmates -- Nicole Stott and spacewalkers Stephen Bowen and Alvin Drew -- were expected to be welcomed home by NASA Administrator Charles Bolden, shuttle program manager John Shannon and scores of other agency managers and engineers who turned out for Discovery's final homecoming.

Over the course of an extended 13-day mission, the astronauts attached a final U.S. module to the International Space Station, delivered a spare set of radiator panels and an external stowage platform and transferred several tons of supplies and equipment to the lab complex.

Bowen and Drew also staged two spacewalks to accomplish a variety of long-planned maintenance tasks. And the astronauts helped their station colleagues service a U.S. oxygen generator and a carbon dioxide removal system.

"When we walk away from her on the runway after we land, there's going to be tears in my eyes, I know," Stott said of Discovery. "I worked with her at Kennedy Space Center and the chance to fly (the last mission) has just been a real, real privilege."

With Discovery safely back on Earth, engineers in the nearby Vehicle Assembly Building made final preparations to haul the shuttle Endeavour to launch pad 39A Thursday for work to ready the ship for its 25th and final launch April 19.

If all goes well, NASA will close out the shuttle program by launching the Atlantis June 28 on a final space station resupply mission.

Discovery's landing brought that long-awaited -- and to some, long-dreaded -- end game into sharp focus. Barratt captured the thoughts of many space workers when he reflected on the shuttle program's legacy from orbit.

"I think about this space shuttle fleet like the clipper ships that were strong and fast and powerful, they did their jobs but they were also graceful and beautiful," he said. "They conjured up imagination, of foreign travel, exotic places, of exploration. And Discovery is just an elite member of this elite fleet.

"The clippers faded, and it was because there was an alternative, there was another ship that was coming in -- steam power -- that was stronger, faster perhaps, but not quite as beautiful.

"We have the legacy of the clippers in our shuttle fleet and it's a legacy that everybody who's ever touched these vehicles should be extremely proud of," he said. "I think the only problem area there is we don't have that follow on, we're not replacing the shuttle with something and I think that's what makes it a little bit sad for us."

At the same time, he said, "it is a time to celebrate."

"The legacy this spaceship has made for herself is just nothing more than cause for celebration, she's returned so much science, so much experience and the experience that we as crew members have had has just been marvelous and again, something our country should be very, very proud of."

In the wake of the 2003 Columbia disaster, the Bush administration ordered NASA to complete the International Space Station and retire the shuttle by the end of fiscal 2010, a target that eventually slipped to June because of a variety of technical issues. The idea was to free up money to develop a new generation of safer, lower-cost rockets and spacecraft to carry astronauts back to the moon by the early 2020s.

But the Bush administration never fully funded the proposed Constellation moon program and President Obama concluded it was not affordable. He ordered NASA to help private industry develop commercial spacecraft to ferry astronauts to and from the space station while the agency focuses on deep space exploration.

How that strategy will play out in the ongoing budget debate is not yet clear. But for the next several years, until a new rocket debuts to replace the shuttle, the only way for U.S. astronauts to reach orbit will be to hitch rides aboard Russian Soyuz spacecraft.

"We won't do anything nearly as complex with another vehicle for a very long time," Drew said Tuesday. "Five or 10 years from now, they're going to look back and say 'how did we ever build a vehicle that could do all these things?'

"This was a pretty bold and audacious thing to put together back in the 1970s and I just don't know if we have that audacity now to build something nearly as ambitious as the shuttle."

Over the next few months, Discovery will be decommissioned and ultimately turned into a museum display.

NASA has not yet announced where the orbiters will end up, but it's widely expected that one of them will be displayed at the Smithsonian's National Air and Space Museum.

The contract authorizing construction of Discovery was awarded Jan. 29, 1979, and initial work to begin building the crew module began the following August. The spacecraft was completed at North American Rockwell's Palmdale, Calif., plant in October 1983 and was ferried to the Kennedy Space Center Nov. 9, 1983.

Following an on-pad main engine test firing June 2, 1984, NASA attempted to launch Discovery on its maiden voyage the following June 26. But in a moment of high drama, the shuttle's main engines shut down seconds after ignition because of a sluggish fuel valve.

The problem was corrected, and commander Henry Hartsfield and his crew, including Challenger astronaut Judith Resnik, finally blasted off Aug. 30, 1984, on a successful mission to deploy three commercial communications satellites and to test space station construction techniques.

Over the next 26 and a half years and 39 flights, Discovery carried out four military missions, two Spacelab science flights, two visits to the Russian Mir space station, one Mir docking and 13 missions to the International Space Station. At least 24 civilian and military satellites were carried into space, including the Hubble Space Telescope.

Discovery also flew the return-to-flight missions following the 1986 destruction of the shuttle Challenger and the 2003 loss of Columbia. In addition, two stranded communications satellites were plucked out of orbit by spacewalking astronauts and brought back to Earth for repairs in November 1984 in what many veterans consider the most daring shuttle mission ever attempted.

"When you really look at the space shuttle and its capability, it can do everything, everything you can think of in space except for one thing, it can't leave low-Earth orbit, but it can do everything else," Lindsey said in a NASA interview

"It can do robotics. It can do science. It can go dock. When you dock with the space station, in the end you have to maintain a three-inch corridor and one degree of attitude error and you can easily fly the shuttle manually and maintain that. I mean, that's unbelievable for a 120-ton vehicle.

"I don't think there's going to be another one that's ever going to match the versatility of the space shuttle, and I think that's the legacy."

=================================

CBS NEWS Coverage of Breaking Space News

06:30 AM, 03/09/11 Update: Discovery astronauts prepare for landing

By WILLIAM HARWOOD
CBS News

With no technical problems and windy but acceptable weather expected, the Discovery astronauts are preparing the veteran spaceplane for its 39th and final re-entry Wednesday to close out an extended space station assembly mission.

Commander Steven Lindsey, and his five crewmates -- pilot Eric Boe, entry flight engineer Nicole Stott, Michael Barratt and spacewalkers Stephen Bowen and Alvin Drew -- have two landing opportunities on successive orbits, the first at 11:57 a.m. EST (GMT-5) and the second at 1:34 p.m.

The Spaceflight Meteorology Group at the Johnson Space Center is predicting scattered clouds at 3,000 and 20,000 feet and winds out of 130 degrees at 15 knots with gusts to 23 knots. That translates into a 21-knot headwind on runway 15, 4 knots below NASA's safety limit.

"Winds will be the only thing that are significant in the forecast right now, 130 at 15, peaking at 23," astronaut Charles "Scorch" Hobaugh radioed the crew from mission control. "That gives you a 10-knot cross and a 21-knot headwind. So right now, the weather looks great."

"OK, copy all those words, Scorch," Lindsey replied. "Thanks."

The astronauts plan to close Discovery's cargo bay doors around 8:12 a.m. If the forecast holds up, Lindsey and Boe will shoot for the first landing opportunity, firing the shuttle's orbital maneuvering system braking rockets at 10:52 a.m. for two minutes an 36 seconds to slow the ship by about 194 mph and drop out of orbit for the long glide home.

After a half-hour free fall, Discovery will slip into the discernible atmosphere at an altitude of 76 miles above the south Pacific Ocean at 11:25 a.m., following a northeasterly trajectory back to Florida. The orbiter will pass above Central America and just west of Cuba before crossing the Florida coast near Sarasota.

Lindsey will take over manual control as Discovery nears the Kennedy Space Center and drops below the speed of sound at an altitude of about 50,000 feet. Guiding Discovery through a 252-degree left turn, Lindsey will line up for a steep 21-degree descent to runway 15 where ground crews and NASA managers will be waiting to welcome the astronauts back to Earth.

NASA is not staffing its backup landing sites in California and New Mexico. If the weather or technical problems prevent a re-entry Wednesday, the astronauts will remain in orbit an additional 24 hours and land Thursday, on one coast or the other.

Here are timelines for both Wednesday landing opportunities:

Orbit 202 descent to KSC

EST...........EVENT

06:52 AM......Begin deorbit timeline
07:07 AM......Radiator stow
07:17 AM......Astronaut seat installation
07:23 AM......Computers set for deorbit prep
07:27 AM......Hydraulic system configuration
07:52 AM......Flash evaporator cooling system checks
07:58 AM......Final payload deactivation
08:12 AM......Payload bay doors closed
08:22 AM......Mission control 'go' for OPS-3 entry software
08:32 AM......OPS-3 transition
08:57 AM......Entry switch list verification
09:07 AM......Deorbit maneuver update
09:12 AM......Crew entry review
09:27 AM......Commander/pilot don entry suits
09:44 AM......Inertial measurement unit alignment
09:52 AM......Commander/pilot strap in; others suit up
10:09 AM......Shuttle steering check
10:12 AM......Hydraulic system prestart
10:19 AM......Toilet deactivation

10:32 AM......Mission control center 'go' for deorbit burn
10:38 AM......Mission specialists seat ingress
10:47 AM......Single hydraulic power unit start
       
10:52:09 AM...Deorbit ignition (altitude: 221 miles)
10:54:40 AM...Deorbit burn complete (dT: 02:36; dV: 194 mph

11:25:57 AM...Entry interface (altitude: 76 miles)
11:30:48 AM...1st roll command to right
11:38:04 AM...1st roll right to left
12:44:00 AM...C-band radar acquisition
11:51:11 AM...Velocity less than mach 2.5 (altitude: 83,600 feet)
11:53:23 AM...Velocity less than mach 1 (altitude: 50,900 feet)
11:54:13 AM...252-degree left turn to runway 15 (altitude: 38,800 feet)
11:57:44 AM...Landing


Orbit 203 Deorbit to KSC

12:09 PM......MCC 'go' for deorbit burn
12:15 PM......MS seat ingress
12:24 PM......Single APU start
       
12:29:24 PM...Deorbit ignition (altitude: 223 miles)
12:32:00 PM...Deorbit burn complete (dT: 02:36; dV: 194 mph)

01:01:58 PM...Entry interface (altitude: 76 miles)
01:06:47 PM...1st roll command to right
01:21:10 PM...C-band radar acquisition
01:23:53 PM...1st right to left roll reversal
01:27:34 PM...Velocity less than mach 2.5 (altitude: 84,300 feet)
01:29:43 PM...Velocity less than mach 1 (altitude: 52,700 feet)
01:29:55 PM...328-degree left turn to runway 15 (altitude 50,000 feet)
01:34:10 PM...Landing

=================================

CBS NEWS Coverage of Breaking Space News

03:30 PM, 03/08/11 Update: Flight director optimistic about weather, Discovery landing Wednesday

By WILLIAM HARWOOD
CBS News

Forecasters are predicting windy but acceptable Florida weather for the shuttle Discovery's return to Earth Wednesday and with virtually no technical problems of any significance, entry Flight Director Tony Ceccacci said "we feel pretty comfortable" about getting the orbiter home on time from its 39th and final flight.

Discovery has enough on-board supplies to remain in orbit until Friday at the latest, but with a favorable forecast Ceccacci said NASA only planned to staff the Kennedy Space Center Wednesday. If the weather takes a turn for the worse and Discovery fails to make it home on one of two landing opportunities, the astronauts will remain in orbit one more day and land Thursday, on one coast or the other.

"It's Florida and it's always 50-50 there, but just based on what the weather guys are forecasting, we feel pretty comfortable" about landing Wednesday, Ceccacci said.

If all goes well, commander Steven Lindsey and pilot Eric Boe will fire Discovery's braking rockets at 10:52 a.m. EST (GMT-5) during the crew's 202nd orbit, setting up a half-orbit plunge back to runway 15 at the Kennedy Space Center. The deorbit rocket firing will last two minutes and 36 seconds, slowing Discovery by about 194 mph, just enough to drop the far side of its orbit deep into the atmosphere.

Assuming an on-time rocket firing, Discovery's trajectory will carry the orbiter over the southern Pacific Ocean on a northeasterly path across Central America and just west of Cuba before crossing the Florida coast near Sarasota for the final descent to the Kennedy Space Center.

After a sweeping left overhead turn, touchdown on runway 15 is expected at 11:57 a.m. A second landing opportunity is available one orbit later at 1:34 p.m.

Ceccacci said the forecast is generally favorable for both Wednesday opportunities, but the outlook changes dramatically Thursday as a frontal system moves across Florida. Electrically charged anvil clouds are expected for the first Thursday opportunity with a chance of showers one orbit later.

"As far as the forecast for KSC Wednesday , they're trending very well and looking very promising," Ceccacci said. "With that, and with the next day's forecast, my plan tomorrow is just only call up KSC. If we needed (an extra day ) for whatever reason we had to wave off tomorrow, end of mission plus one would become 'pick 'em day,' we would come home (somewhere)."

The forecast for Edwards Air Force Base, Calif., and Northrup Strip in New Mexico is favorable Thursday and Friday.

Here are timelines for both of the crew's landing opportunities Wednesday (in EST; times are approximate):

Rev. 202 deorbit to KSC
Deorbit dT: 02:36
Deorbit dV: 194 mph

EST...........EVENT

06:52 AM......Begin deorbit timeline
07:07 AM......Radiator stow
07:17 AM......Astronaut seat installation
07:23 AM......Computers set for deorbit prep
07:27 AM......Hydraulic system configuration
07:52 AM......Flash evaporator cooling system checks
07:58 AM......Final payload deactivation
08:12 AM......Payload bay doors closed
08:22 AM......Mission control 'go' for OPS-3
08:32 AM......OPS-3 transition
08:57 AM......Entry switchlist verification
09:07 AM......Deorbit PAD update
09:12 AM......Crew entry review
09:27 AM......Commander/pilot don entry suits
09:44 AM......Inertial measurement unit alignment
09:52 AM......Commander/pilot strap in; others suit up
10:09 AM......Shuttle steering check
10:12 AM......Hydraulic system prestart
10:19 AM......Toilet deactivation

10:32 AM......Mission control center 'go' for deorbit burn
10:38 AM......Mission specialists seat ingress
10:47 AM......Single APU start
       
10:52:09 AM...Deorbit ignition
10:54:40 AM...Deorbit burn complete

11:25:57 AM...Entry interface
11:30:48 AM...1st roll command to right
11:38:04 AM...1st roll right to left
12:44:00 AM...C-band radar acquisition
11:51:11 AM...Velocity less than mach 2.5
11:53:23 AM...Velocity less than mach 1
11:54:13 AM...Right turn to runway 15
11:57:44 AM...Landing


Rev. 203 Deorbit to KSC
Deorbit dT: 02:31
Deorbit dV: 188 mph

EST...........EVENT

12:09 PM......MCC 'go' for deorbit burn
12:15 PM......MS seat ingress
12:24 PM......Single APU start
       
12:29:24 PM...Deorbit ignition
12:32:00 PM...Deorbit burn complete

01:01:58 PM...Entry interface
01:06:47 PM...1st roll command to right
01:21:10 PM...C-band radar acquisition
01:23:53 PM...1st right to left roll reversal
01:27:34 PM...Velocity less than mach 2.5
01:29:43 PM...Velocity less than mach 1
01:29:55 PM...Right turn to runway 15
01:34:10 PM...Landing

=================================

CBS NEWS Coverage of Breaking Space News

01:30 PM, 03/08/11 Update: Shuttle crew reflects on the legacy of Discovery

By WILLIAM HARWOOD
CBS News

On the eve of returning to Earth Wednesday to close out the shuttle Discovery's 39th and final flight, the ship's crew said the nation should be proud of the shuttle program's accomplishments, but expressed concern that a replacement vehicle is not waiting in the wings to replace it.

Here is a transcript of a CBS News interview with shuttle commander Steven Lindsey, pilot Eric Boe, Michael Barratt, Nicole Stott and spacewalkers Stephen Bowen and Alvin Drew.

CBS News: Commander Lindsey, you've probably said, and we've probably reported, everything that can possibly be said about this being the last flight for Discovery. For somebody who flies these things for a living, how hard is it to retire a spacecraft that seemingly has a lot of life left in her?

Lindsey: I guess it's going to be sad when it's over, when we land tomorrow or the next day. I guess the hardest part of this for me is giving up the capability, because if you really look at what this spacecraft does, it can do everything except leave low-Earth orbit. It's a science laboratory, it can dock with space stations, we did build the U.S. segment of the International Space Station with these vehicles, hauled cargo and people up and down with up mass and down mass that's unmatched anywhere. We deployed the Hubble Space Telescope with this vehicle.

It starts out its life as a rocket, becomes an orbiting laboratory or a docking vehicle, a maneuverable spacecraft on orbit and lands like an airplane. That capability is unmatched anywhere and probably will be unmatched for many, many, many years to come. And so, giving up all of that capability and the amazing versatility of this spacecraft is what's the most difficult for me, and probably for everybody who's working in the program.

CBS News: And along those lines for Nicole Stott, with so much uncertainty right now with the future of U.S. manned spaceflight, what are your concerns? And what are the things that most excite you about what's ahead?

Stott: I think from the concern standpoint right now, I think we're still in this phase of really defining what the next steps are going to be and I look forward to seeing what that is. I hold real hope that we'll be challenging ourselves, we'll be doing big things and going out of low-Earth orbit. I would love to see us go back to the moon, I don't know if that's in the plans or not, but I hope that what will be happening is a challenge, and will be taking us places as much as vehicles like Discovery and the space shuttle have done for us and that we'll be learning all kinds of new things. I think that's what makes it exciting as well. There's plenty of opportunities out there. We're a great country that's done really, really amazing things with our space program and I really just hope that that will continue.

CBS News: I think to a lot of people, your mission is the first really concrete sign that the beginning of the end is finally here for this program. For MIke Barratt, what do you say to the workforce, and really to all Americans, on the eve of this final landing for Discovery?

Barratt: I think about this space shuttle fleet like the clipper ships that were strong and fast and powerful, they did their jobs but they were also graceful and beautiful. They conjured up imagination, of foreign travel, exotic places, of exploration. And Discovery is just an elite member of this elite fleet. The clippers faded, and it was because there was an alternative, there was another ship that was coming in, steam power that was stronger, faster perhaps, but not quite as beautiful.

We don't have that yet, we have the legacy of the clippers in our shuttle fleet and it's a legacy that everybody who's ever touched these vehicles should be extremely proud of. I think the only problem area there is we don't have that follow on, we're not replacing the shuttle with something and I think that's what makes it a little bit sad for us. But make no mistake, when we bring Discovery home it is a time to celebrate. I mean, the legacy this spaceship has made for herself is just nothing more than cause for celebration, she's returned so much science, so much experience and the experience that we as crew members have had has just been marvelous and again, something our country should be very, very proud of.

CBS News: When you talk to folks who've worked on the shuttle over the years, there's almost a sense of disbelief that it's come to this, that the agency's been told to give up a very mature, operational vehicle, arguably the most capable spacecraft ever built, in favor of less ambitious vehicles that have not yet been designed or tested. Do any of you resent the way this has played out? Or is it simply the shuttle's time to go?

Lindsey: That's a tough question to answer. Obviously, we have a vision, we're looking at expanding out of low-Earth orbit and so the objective, as part of retiring the shuttle the plan was to go out of low-Earth orbit and from what I've seen so far, that's what we're still intent on doing. To go there with the budget and what we have right now, we really can't afford to do all of that. So to take the next step and get out of low-Earth orbit, we have to go to a different type of vehicle to do that.

And so, it's sad to give up this kind of capability, although I think someday in the future we'll probably have similar capability. I don't know when that would be, but I really, strongly believe in the next step, as Nicole mentioned earlier, to try to get out of low-Earth orbit, go to an asteroid, go to the moon, get out and explore the solar system. We do need a new vehicle for that.

CBS News: Nicole, you worked on the space shuttle at the Kennedy Space Center before you joined the astronaut corps, you know better than most what an amazing machine Discovery is, and the other two orbiters. As you look out the window, what are your thoughts on the eve of this final landing for Discovery?

Stott: Certainly there are the thoughts of bringing this vehicle to wheels stopped on the runway for the last time. But like Steve mentioned earlier about the team that's associated with this, I think that's really what I'm going to be thinking about. As I look out the windows, I feel really, really blessed to have had the opportunity to not only work on Discovery and the other orbiters on the ground but also to just have this opportunity to look out the windows and appreciate it from the inside as well. (Saying) thanks has just continued to come to mind for me, thanking the people on the ground who have taken such meticulous care of these vehicles. It's in their bones, this is a passion for them, this is not just 'I go to work every day,' it really is a heart-and-soul kind of thing. I think that's what it's coming down to for me, thinking about that and appreciating just how much has gone into this by this wonderful team of people who have taken such good care of these vehicles.

CBS News: This question is for Eric Boe. You've got kids and down the line, maybe some grandchildren on the way, who will only know about the space shuttle from history books and from video and things on the internet. Maybe you'll take them to see Discovery at the Smithsonian, or wherever it winds up. What will you tell them about what it was like to fly the space shuttle?

Boe: I'll tell them that Discovery and the space shuttle fleet was a dream machine. It's just amazing what this vehicle can do. It can launch like a rocket, go into orbit, change it into a spacecraft and then land as a hypersonic airplane. What's amazing is just how well she sails. It's an honor and privilege for all of us to get the chance (to fly) on her final voyage.

=================================

CBS NEWS Coverage of Breaking Space News

04:50 AM, 03/08/11 Update: Discovery crew enjoys 'live' wakeup call; packs for re-entry

By WILLIAM HARWOOD
CBS News

In a first for mission control and a shuttle crew, the Discovery astronauts were awakened Tuesday with a live performance of "Blue Sky" by Big Head Todd and the Monsters, a tune inspired by the first post-Columbia mission. The song won the most votes in a NASA "Top 40" competition giving the public an opportunity to select the crew's wakeup music.

Playing an acoustic guitar, band leader Todd Park Mohr, singing solo but flanked by his three fellow musicians, serenaded the astronauts at 3:23 a.m. EST (GMT-5) to kick start Discovery's final full day in space.

"We've waited long for this day to come," he sang, "for all the midnight lights we've burned into the morning sun, I can't wait to see your sweet mysteries, the moon, the stars, the sun, the universe, the galaxies.

"Fly home on your silver wings, with your new song for the world to sing, light this candle, make it right."

Big Head Todd and the Monsters won a NASA competition allowing the public to pick two of the Discovery crew's wakeup songs, winning 722,662 of the more than 2.4 million votes cast. Second place went to the theme from the "Star Trek" television series, which was beamed up to the crew Monday with a voice over by William Shatner marking Discovery's final mission.

"Hello everybody. Greetings, this is Todd from Big Head Todd and the Monsters," Mohr radioed Discovery from mission control.

"Well, good morning, Todd, thanks very much for that," commander Steven Lindsey replied from orbit. "That was great. Did you just do that live?"

"I did just do that iive, and I believe it's a first in history."

"Well, that was terrific, we really appreciate it and congratulations on winning the contest," Lindsey said.

"Well, on behalf of Big Head Todd and the Monsters and songwriters and artists everywhere, we just want to thank you so much for your courage and your bravery and your effort in just giving all of us a better shot at knowing more. It's very inspirational to the arts as well. I just want you to be home safely and as soon as you can."

"Thank you very much," Lindsey said. "We all wish you could see what we can see when we look out at the Earth and hopefully, everybody will be able to do that one of these days. Hopefully sooner rather than later."

"We'll work on that together. Thank you so much."

Lindsey and his crewmates -- pilot Eric Boe, entry flight engineer Nicole Stott, Michael Barratt and spacewalkers Stephen Bowen and Alvin Drew -- planned to test the shuttle's re-entry systems early Tuesday and rig the ship for re-entry and landing Wednesday back at the Kennedy Space Center to close out the shuttle's 39th and final mission.

Forecasters are predicting generally good, if windy, conditions at the Florida spaceport Wednesday, with rain and thunderstorms expected Thursday. Good weather is expected both days at Edwards Air Force Base, Calif., and conditions should improve in Florida by Friday.

CBS News, ABC News and The Associated Press will interview the astronauts starting at 11:23 a.m., followed by a crew tribute to Discovery at 12:08 p.m. A Mission Management Team update on the health of Discovery's heat shield is planned for 12:30 p.m. and a briefing with entry Flight Director Tony Ceccacci is on tap at 2 p.m.

Discovery is scheduled to end its final mission with a touchdown on runway 15 at 11:57 a.m. Wednesday.

The crew of the next shuttle mission -- commander Mark Kelly, pilot Gregory H. Johnson, Michael Fincke, Gregory Chamitoff, Andrew Feustel and Roberto Vittori -- will be on hand later in the day to watch the shuttle Endeavour's final roll out to pad 39A for work to ready the ship for launch April 19.

The Discovery crew will participate in a final news conference around 6:30 p.m. Wednesday. Kelly and his crewmates plan to field questions shortly after Endeavour's rollout gets underway.

Here is an updated timeline of the Discovery crew's activities for Tuesday (in EST and mission elapsed time; includes rev. L of the NASA TV schedule):

DATE/EST...DD...HH...MM...EVENT

03/08
03:23 AM...11...10...30...STS crew wakeup
06:28 AM...11...13...35...Flight control system checkout
06:28 AM...11...13...35...Cabin stow begins
07:38 AM...11...14...45...Reaction control system hotfire
07:48 AM...11...14...55...PILOT landing practice
10:23 AM...11...17...30...Crew meal
09:53 AM...11...17...00...Deorbit review
11:23 AM...11...18...30...CBS News/ABC News/AP interviews
11:58 AM...11...19...05...Cabin stow resumes
12:08 PM...11...19...15...Crew tribute to Discovery
12:30 PM...11...19...37...MMT briefing on NTV
01:00 PM...11...20...07...Voyager news conference on NTV
02:00 PM...11...21...07...Mission status briefing on NTV
02:13 PM...11...21...20...L-1 comm check
02:43 PM...11...21...50...Ergometer stow
03:53 PM...11...23...00...Wing leading edge sensor deactivation
04:13 PM...11...23...20...Laptop computer stow (part 1)
04:13 PM...11...23...20...Ku-band antenna stow
07:23 PM...12...02...30...Crew sleep begins
09:00 PM...12...04...07...Daily highlights reel (repeated hourly)

=================================

CBS NEWS Coverage of Breaking Space News

By WILLIAM HARWOOD
CBS News

The crew of the shuttle Discovery, given a "Star Trek" send off by actor William Shatner, undocked from the International Space Station early Monday to close out an extended assembly and resupply mission, the shuttle's 13th and final visit to the orbital outpost.

With pilot Eric Boe at the controls, Discovery's docking system disengaged from the station's forward port at 7 a.m. EST (GMT-5) as the two spacecraft sailed through orbital darkness above the western Pacific Ocean northeast of Australia.

"Houston and station, physical separation," commander Steven Lindsey called as the orbiter began backing away.

Manually guiding the shuttle to a point about 400 feet directly in front of the lab complex, Boe kicked off a 360-degree fly-around, looping up over, behind and below the space station to capture photographs and video showing a final U.S. module in place, along with a full complement of visiting spacecraft from Europe, Japan and Russia.

"We've been talking about the long history of the space shuttle, and it's a privilege to get the opportunity to undock and do the fly around of the space station," Boe said during a crew news conference earlier this week.

"What's amazing is how big the structure is. Right now, when we're docked, it's more than a million pounds and to actually fly around the vehicle, take pictures and marvel that the majority of the U.S. segment was brought up, piece by piece, by the space shuttle will be truly amazing."

NASA managers earlier asked their Russian counterparts to consider undocking a Soyuz spacecraft for a fly-about to capture views of the station with Discovery attached. But Russian mission managers, citing technical considerations, declined.

Discovery's fly around took a little more than an hour to complete. At 8:09 a.m., the ship's maneuvering jets were fired in the first of two maneuvers to break away and leave the area.

"Steve, as you guys are heading home, I wanted to say one last time that we really enjoyed your company on board," radioed Expedition 26 commander Scott Kelly, who is scheduled to return to Earth March 16 aboard a Russian Soyuz spacecraft. "And I'm really proud of what we accomplished together as a team here on the space station. But also, including the larger team in Houston and all the control centers around the world.

"Doing something as complicated as this really takes a team effort and that's, I think, what we've proven here this last week. I'd like to wish you guys a safe rest of your fight and a safe landing. And I will see you all back in Houston here in about a week or so."

"Hey Scott, I couldn't agree more, I think the team effort between our two crews and the larger ground team that planned this and put it all together enabled us to get well over 100 percent of our objectives," Lindsey replied. "It's been a pleasure working with your team and I look forward to seeing you guys. Have safe travels for everybody on board and we will see you in about a week."

"OK, take care," Kelly called. "Station out."

Over the course of an extended docked mission, the Discovery astronauts delivered a new storage module, an external spare parts platform, an extra set of radiator panels and several tons of supplies, science gear and other equipment. They also staged two spacewalks to perform a variety of maintenance tasks outside the station and helped out with work to service one of the station's oxygen generators and a carbon dioxide removal system.

Throughout it all, Discovery performed flawlessly, allowing mission planners to extend the docked mission by two days.

"I think if I had to step back and characterize this entire mission, I would really call it an above-and-beyond mission." said Kenneth Todd, chairman of the space station Mission Management Team. "The systems performed very, very well to the point where we were able to add a couple of extra days, which we just don't do that often. ... Being able to get that work behind us now with a larger crew was very, very helpful for us."

But watching Discovery depart early Monday, he said, was a bittersweet moment.

"To see Discovery leave, she had done just a flawless mission for us in support of the program, and yet as she was backing away it was clear to us that that was the last time she was going to visit us," he said. "So we bid her adieu and certainly Godspeed to Steve and the rest of the crew on the way home."

Lindsey, Boe and their crewmates -- Nicole Stott, Michael Barratt and spacewalkers Stephen Bowen and Alvin Drew -- got in the proper spirit for undocking with a 3:23 a.m. wakeup song from Houston that was voted the second most popular in a NASA contest: the Alexander Courage theme from the 1960s television series "Star Trek."

As with the original, Shatner began with the familiar phrase "Space... the final frontier." But the rest was a tribute to Discovery, making its 39th and final flight since its maiden launch in 1984.

"Space... the final frontier," Shatner said as the music played. "These have been the voyages of the space shuttle Discovery. Her 30-year mission: to seek out new science, to build new outposts, to bring nations together on the final frontier, to boldly go and do what no spacecraft has done before."

"And good morning, Houston," Lindsey replied when the music faded. "And that was, I believe, the second most popular selection from the song contest for the space shuttle program and I'd like to thank William Shatner for taking the time to record that special introduction for us."

The song voted most popular in the wakeup music contest -- "Blue Sky" by Big Head Todd and the Monsters -- will be beamed up to the astronauts Tuesday.

The rest of the shuttle crew's day was devoted to carrying out a final inspection of the shuttle's reinforced carbon carbon nose cap and wing leading edge panels to look for any signs of impact damage from micrometeoroids or orbital debris since a similar inspection the day after launch.

The so-called "late inspection" was completed around 3:45 p.m. Analysts at the Johnson Space Center in Houston will review photos and laser scans to make sure the heat shield is in good shape for re-entry.

The astronauts plan to pack up and test Discovery's re-entry systems Tuesday before dropping out of orbit and landing back at the Kennedy Space Center around noon Wednesday.

That night, starting around 8 p.m., engineers plan to haul the shuttle Endeavour to the launch pad for work to ready the ship for its final blastoff April 19.

Between now and then, the station program faces a particularly busy schedule. Using the lab's robot arm, the Expedition 26 crew plans to move a Japanese cargo ship from the upper port of the forward Harmony module to an Earth-facing port early Thursday.

Kelly and his two Soyuz TMA-01M crewmates -- Alexander Kaleri and Oleg Skripochka -- plan to undock and return to Earth early the morning of March 16, leaving the station in the hands of cosmonaut Dmitry Kondratyev, who will become commander of Expedition 27, Italian astronaut Paolo Nespoli and Catherine "Cady" Coleman.

Three fresh crew members -- Alexander Samokutyaev, Andrei Borisenko and Ronald Garan -- are scheduled for launch March 29, the day after the Japanese HTV cargo ship, loaded with no-longer-needed equipment and trash, is jettisoned for a fiery plunge back into the atmosphere. The Soyuz TMA-21 spacecraft carrying Samokutyaev, Borisenko and Garan is scheduled to dock at the station's upper Poisk module late the night of March 31 U.S. time.

Less than three weeks after that, the shuttle Endeavour is scheduled for launch on its final visit to the station.

=================================

CBS NEWS Coverage of Breaking Space News

By WILLIAM HARWOOD
CBS News

After transferring a final few items to and from the International Space Station -- and enjoying a bit of zero-gravity fun in a roomy new storage module -- the Discovery astronauts bid their station colleagues farewell Sunday, floating back aboard the orbiter to rig the ship for undocking early Monday to wrap up the shuttle's 13th and final visit.

During a brief farewell ceremony in the U.S. Destiny laboratory module, Discovery commander Steven Lindsey thanked Expedition 26 commander Scott Kelly for the lab crew's hospitality during an extended eight-day visit.

"Scott, it was a pleasure being up here, we appreciate your hospitality, we appreciate your putting up with us knocking your stuff off the walls and generally trashing your station, doubling the number of people," Lindsey said. "On behalf of the crew, we had a great time, we appreciated the hospitality, enjoyed the crew meals together and we're going to miss you guys. So thanks for everything."

Kelly said the station crew "really enjoyed having guests."

"This is the first group of guests I've had in about 150 days," he said. "We're going to miss you but most of all, we're going to miss Discovery. Discovery has been a great ship and has really supported the International Space Station, more so than, I think, any other space shuttle. We wish her fair winds and following seas."

As the shuttle crew floated forward, through the Harmony module and into the hatchway leading to Discovery, space station Flight Director Royce Renfrew called from mission control in Houston to tell the astronauts "it's been an honor and a privilege to work this mission with you."

"A couple of folks have asked me recently what I would feel at this moment, and I think the answer is I just feel really proud to take Discovery home at the very top of her game," he said. "And a lot of the credit goes to the on-board crew. You guys rock."

The Discovery astronauts then floated back into the shuttle, closing the ship's hatch at 4:11 p.m.

The combined crews finished their resupply transfer work earlier Sunday and shared a final joint meal before the shuttle astronauts took a break to relax and enjoy the view. Shortly before the farewell ceremony, several shuttle astronauts could be seen frolicking in the newly installed Permanent Multipurpose Module, spinning about, cartwheeling and running around the walls.

"It looks like there's people playing hamster wheel in the PMM, so be careful when you go in there," mission control communicator Stan Love jokingly radioed station flight engineer Catherine "Cady" Coleman.

Discovery's crew delivered the 21,817-pound Permanent Multipurpose Module, loaded with supplies and equipment, to the space station and a 7,611-pound external cargo platform carrying a spare set of radiator panels. The astronauts also transferred another 2,031 pounds of equipment from the shuttle crew cabin to the station and delivered 853 pounds of water, 112 pounds of nitrogen and 182 pounds of oxygen. Another 2,599 pounds of equipment and experiment samples were moved from the station to Discovery for return to Earth.

In addition to the crew's resupply work, astronauts Alvin Drew and Stephen Bowen staged two successful spacewalks to carry out a variety of maintenance chores outside the lab complex.

"The shuttle crew's doing great, the station crew is doing great, the vehicles are in great shape and all in all, we couldn't be more pleased with how this mission is going," said shuttle Flight Director Bryan Lunney.

Lunney, the son of legendary Apollo flight director Glynn Lunney, faces his final shift Monday. With the shuttle program winding down, Lunney is leaving NASA to take a job in private industry. Asked if Discovery's final undocking might prompt an emotional moment in mission control, Lunney said the focus will remain squarely on carrying out the remainder of the mission.

"For us on console, it's stick with business, take care of the crew, take care of the vehicle, make sure everything's going well," he said. "The emotion may kick in later after we unplug for our last shift. Tomorrow will be my last shift and afterwards, perhaps it'll be a little emotional. But for the most part, we'll just be excited the mission has gone so darn well."

Along with delivering needed supplies and equipment to the station, the combined crews also performed needed maintenance on the station's oxygen generator and one of its carbon dioxide removal systems.

Kelly worked earlier Sunday to remove maintenance equipment from the oxygen generation assembly in the U.S. Tranquility module after work Saturday to adjust the chemistry of supply water and to install a filter intended to prevent particulates from clogging internal components.

The OGA works by using electricity to break water down into hydrogen and oxygen. The device was activated briefly Saturday after the filter was installed to collect water samples that will be returned to Earth aboard Discovery for detailed analysis. If the water meets specifications, the OGA will be returned to normal operation in the near future.

The astronauts also serviced a carbon dioxide removal assembly in the U.S. Destiny laboratory module Saturday, carrying out a bit of electronic surgery to bypass a short circuit in a heater assembly. The repair work went well and Edelen said the device appeared to be working normally.

With hatch closure, the shuttle astronauts now will turn their attention to undocking Monday at 7 a.m. It will be Discovery's 13th and final departure from the space station as the veteran spaceplane sails into its last three days in space.

With pilot Eric Boe at the controls, Discovery will pull straight away from the station to a point about 400 feet in front of the lab complex. Boe then will guide the shuttle through a 360-degree loop of the station before leaving the area for good around 8:43 a.m. (a detailed undocking timeline is posted on the Flight Data File page).

After a final heat shield inspection Monday, the astronauts will pack up and test the shuttle's re-entry systems Tuesday. Landing back at the Kennedy Space Center to close out Discovery's 39th and final mission is expected just before noon Wednesday.

=================================

CBS NEWS Coverage of Breaking Space News

06:45 AM, 03/05/11/10 Update: Astronauts focus on space station maintenance, cargo transfers

By WILLIAM HARWOOD
CBS News

The Discovery astronauts and their space station counterparts are wrapping up work to unload a newly attached storage module and carrying out maintenance to bypass a short circuit in a U.S. carbon dioxide removal system. Station commander Scott Kelly also plans to install a needed filter to restore an oxygen generator to normal operation.

The complexity of the repair work on the carbon dioxide removal assembly, or CDRA, and the oxygen generation assembly, or OGA, prompted NASA to call in additional flight controllers to oversee the procedures and the operation of the lab's life support systems.

"Just the mere task of preparing these procedures for execution is pretty involved," said station Flight Director Chris Edelen. "We've had teams of maintenance flight controllers -- they're called the operations support officers, or OSOs -- they're working in concert with the engineering (and safety) experts to develop the procedures to make sure there are no hazards. They're also working closely with our environmental control and life support team.

"We'll actually staff extra flight controllers during the day, two extra OSOs, they'll be monitoring CDRA, OGA and the outfitting going on in (the storage module) Leonardo, and we'll have an extra ECLSS (officer) to work the OGA activation while the other ECLSS monitors the normal vehicle functions. So it's a little bit unusual for us, but the pace of work is so high right now we're having to bring in extra personnel."

The International Space Station features two U.S. CDRA units, one in the Destiny laboratory and one in the Tranquility module. The Russian segment of the station has its own CO2 scrubber, called Vozdukh, which has been operating intermittently over the past several days.

Cabin air moving through the U.S. carbon dioxide removal assembly passes through two beds of zeolite crystals that trap CO2. The beds are then heated to drive off the carbon dioxide, which is dumped overboard. Each zeolite bed is equipped with two heaters, a primary and a backup.

The active heater on one of the beds in the CDRA mounted in the Destiny laboratory module shorted out earlier in the week.While the unit remained operational using a backup heater, the loss of redundancy prompted activation of the second CDRA in the Tranquility module. Engineers now want the crew to perform a bit of electrical surgery on the lab unit to prevent any additional problems.

"The primary heater had an electrical short and the engineers are concerned that the way that short occurred, that failure could propagate to the secondary string," Edelen said. "So they want us to identify exactly where in the wiring the short took place and then snip the wires so there's no chance of a current getting into that circuit and causing the failure to propagate to the other string of heaters, which would essentially take down the lab CDRA.

"So Mike Barratt and Paolo Nespoli will take apart the lab's heater, they'll pull out the bed and they'll use a multimeter, just like you might if you were an electronic enthusiast, they'll use that multimeter to check the pins on the plug and they'll find out where the short is by the resistance in the circuit. Then they'll snip the appropriate wire."

While that work is going on, Kelly plans to install a filter in the U.S. oxygen generation assembly to restore that device to normal operation.

For the past several months, the station crew has been using oxygen brought up aboard visiting Progress supply ships, a European cargo craft and the Russian Elektron oxygen generator while awaiting delivery of the OGA repair equipment.The OGA, like the Elektron, uses electricity to split water molecules into hydrogen and oxygen.

"The OGA over the past six months has not been running well because the water that's been fed to it is just slightly too acidic," Edelen said. "We've done some pH tests on the OGA and the engineers have determined that because the pH is not quite balanced right, there was a breakdown in the reaction beds inside the OGA such that material is being released and that material can clog the little holes, the little pores, which can decrease the effectiveness of the OGA at generating (oxygen).

"So what we're going to do, Scott Kelly is going to take basically a water filter and it's going to correct the acidity in the OGA and we're going to take some samples to make sure it works good and we're going to run the OGA and generate a little bit of oxygen and confirm that that new filter works correctly. This'll be an important step towards giving us the capability to generate oxygen from the water that we recycle on board."

The Discovery astronauts were awakened at 3:24 a.m. Saturday by a recording of Bowling for Soup's "Ohio (Come Back to Texas)" radioed up from mission control.

"Good morning, Discovery," called astronaut Michael Massimino in Houston. "That song comes to you from your families, it's for the whole crew. They do want you back here in Texas, we're looking forward to seeing you back on planet Earth when your mission is complete. Good morning."

"Good morning, Mike, and thanks to our families, who have really, really supported us from the beginning all the way through this mission," replied shuttle commander Steven Lindsey. "We really appreciate them and really look forward to seeing them again."

Discovery's mission was extended two days to give the combined crews more time to unload the Permanent Multipurpose Module that was attached to the station Tuesday. If all goes well, the transfer work will be completed Sunday, hatches will be closed Sunday afternoon and Discovery will undock Monday morning around 7 a.m. Landing back at the Kennedy Space Center is targeted for 11:56 a.m. Wednesday.

Here is an/10 Updated timeline of the crew's activities for Saturday (in EST and mission elapsed time; includes rev. I of the NASA TV schedule;):

DATE/EST...DD...HH...MM...EVENT

03/05
03:23 AM...08...10...30...Crew wakeup
04:48 AM...08...11...55...ISS daily planning conference
05:13 AM...08...12...20...OGS quick disconnect/tool gather
06:13 AM...08...13...20...OGS setup
06:23 AM...08...13...30...Lab CDRA bed removal
07:23 AM...08...14...30...Lab CDRA J1 test
07:43 AM...08...14...50...OGS filter installation
10:23 AM...08...17...30...Joint crew meal
11:18 AM...08...18...25...OGS leak check sample
11:23 AM...08...18...30...Lab CDRA heater isolation
11:23 AM...08...18...30...Undefined crew activity
11:43 AM...08...18...50...OGS APT install
04:38 PM...08...23...45...ISS daily planning conference
06:30 PM...09...01...37...Mission status briefing on NTV
06:53 PM...09...02...00...ISS crew sleep begins
07:23 PM...09...02...30...STS crew sleep begins
09:00 PM...09...04...07...Daily highlights reel (repeated hourly)

=================================

CBS NEWS Coverage of Breaking Space News

07:10 AM, 03/04/11/10 Update: Astronauts focus on module unpacking, equipment transfers

By WILLIAM HARWOOD
CBS News

The Discovery astronauts are focusing on unloading the newly attached Permanent Multipurpose Module, or PMM, today, moving science gear and other equipment into the International Space Station. All 12 shuttle-station astronauts and cosmonauts plan to participate in a joint crew news conference at 10:48 a.m. EST (GMT-5) to discuss the progress of Discovery's mission.

Space station Flight Director Chris Edelen said flight planners are busy developing a revised timeline for Discovery's crew to account for a second extra day docked to the space station. NASA managers decided Thursday to add the bonus day to give the crew more time to help unload the PMM and to carry out required space station maintenance.

"What we're going to be doing on that day, so far, the plan is to work on our lab CDRA, that's the carbon dioxide removal assembly, and we're also planning to do some work on our oxygen generator, our OGA, oxygen generation assembly," Edelen said.

Two day ago, a heater used in the carbon dioxide removal assembly mounted in the station's Destiny laboratory module shorted out. A backup heater is working normally but to provide additional margin, station commander Scott Kelly and Catherine Coleman installed a new zeolite "bed" in a second CDRA unit Thursday. Engineers completed activation and checkout of the second CDRA overnight and it appears to be working normally.

The CDRA system uses beds of zeolite crystals to trap carbon dioxide while allowing oxygen and nitrogen to pass through. Periodically, heaters are used to drive off the trapped CO2, which is vented overboard. During normal operations, one bed is used for CO2 removal while the other is being purged.

"We had a problem with the lab CDRA ... that's been doing the bulk of the carbon dioxide removal for this mission so far," Edelen said early Friday. "It experienced a heater short. ... The primary heater had a short and failed. The engineers have had some time to look at that failure signature and ... there is concern that short could propagate to the other heater and if it died, if we lost both heaters on that bed, we would essentially lose half the capability of that CDRA.

"So, the plan we are looking at for our flight day 10, the second extra day, is to have the crew go in and take the bed out of the lab CDRA and snip the wires to the failed heater, sort of like a James Bond movie, but not quite as dramatic with zero zero seven seconds remaining on the clock. But still, we need to be really careful when we do this to make sure we snip the right wire."

The Russian segment of the station uses a different system for CO2 removal. The cosmonauts have been working the past several days to restore their Vozdukh unit to normal operation after a series of glitches. Edelen reported today the system appears to be operating normally at full capacity.

Along with scheduling maintenance activity, NASA planners also are looking at the possibility of moving up work to unpack Robonaut 2, an experimental technology demonstration robot that was carried to the station inside the Permanent Multipurpose Module. The robot, still secured in its launch packaging, has been moved into the Destiny module to make room for PMM unloading.

During a call to the space station Thursday, President Barack Obama joked about getting Robonaut unpacked, urging the astronauts to "let him stretch his legs pretty soon."

Robonaut doesn't actually have legs -- it is an upper torso only -- and NASA does not plan to begin testing for several months. But the astronauts may move up work to unpack protective foam so it can be moved to a Japanese cargo ship that is scheduled to be jettisoned March 28.

"The president was very interested in when we're doing to unpack Robonaut," Edelen said. "So we definitely need to get busy getting him out of his packing crate."

Here is an/10 Updated timeline of the crew's activities for flight day eight (in EST and mission elapsed time; includes rev. G of the NASA TV schedule):

DATE/EST...DD...HH...MM...EVENT

03/04
04:23 AM...07...11...30...STS/ISS crew wakeup
06:08 AM...07...13...15...ISS daily planning conference
07:08 AM...07...14...15...PAO event
07:33 AM...07...14...40...Permanent Multipurpose Module outfitting begins
07:43 AM...07...14...50...Lab 1P4 storage rack transfer
08:33 AM...07...15...40...ERB transfer
09:58 AM...07...17...05...A4 treadmill relocate
10:38 AM...07...17...45...PMM flag ceremony
10:48 AM...07...17...55...Joint crew news conference
11:33 AM...07...18...40...Joint crew photo
11:53 AM...07...19...00...Joint crew meal
12:00 PM...07...19...07...Interpreted replay of crew news conference
12:53 PM...07...20...00...PMM outfitting continues
01:18 PM...07...20...25...A1 stow reconfig/F3 unpack from stowage platform
01:18 PM...07...20...25...F3 stowage platform removal
02:53 PM...07...22...00...P3 unpack from stowage platform
03:38 PM...07...22...45...S3 storage rack deploy
03:38 PM...07...22...45...P3 stowage platform removal
04:28 PM...07...23...35...ISS daily planning conference
06:00 PM...07...01...07...Mission status briefing on NTV
06:53 PM...08...02...00...ISS crew sleep begins
07:23 PM...08...02...30...STS crew sleep begins
08:00 PM...08...03...07...Daily highlights reel on NTV (repeated hourly)

=================================

CBS NEWS Coverage of Breaking Space News

By WILLIAM HARWOOD
CBS News

The Discovery astronauts worked through a busy morning in space Thursday, took the afternoon off and enjoyed a long-distance call from President Barack Obama, who praised NASA's oldest shuttle for a "critical and iconic" final flight to the International Space Station.

"I wanted to call and just say how personally proud I am of you and all that you're accomplishing," Obama said in a phone call from the White House. "We are always inspired by the images of you guys at work as you put some of the final pieces in place to make ISS fully operational. You are setting such a great example with your dedication, your courage, your commitment to exploration. These are traits that built America and you guys personify them."

Speaking to Discovery commander Steven Lindsey, the president said "it must be a great honor to be the last commander of Discovery. It's traveled more distance in space and spent more time in orbit than any of its peers in the shuttle fleet. So, it's appropriate that it's performing this critical and iconic mission and adding to the legacy by working on this ISS assembly to full operations."

Floating in the Destiny laboratory module with his 11 shuttle and station crewmates, Lindsey told the president it was a privilege to command the spaceplane's 39th and final flight.

"We think that when we land (next Wednesday), Discovery will have flown in space for 365 days, so for a whole year, which is pretty incredible for a vehicle," he said. "She won't be forgotten for a long, long time."

Obama praised the international cooperation that built the space station and joked about an experimental robot known as Robonaut 2, or R2, that Discovery carried into orbit.

"I understand you guys have a new crew member, this R2 robot," Obama said. "I don't know whether you guys are putting R2 to work, but he's getting a lot of attention. That helps inspire some young people when it comes to science and technology. Are you guys making him do chores up there, washing the dishes or something? Or does he have more exciting jobs?"

Lindsey told the president Robonaut 2 is still packed up in protective foam, joking that "every once in a while we hear some scratching sounds from inside, maybe, you know, 'let me out, let me out,' we're not sure."

Obama closed the conversation with a personal aside to space station commander Scott Kelly. Kelly's twin brother, Mark, who will command the next shuttle mission in April, is married to Rep. Gabrielle Giffords, who suffered a gunshot wound to the head during a Tucson shooting spree in January.

"Scott, I talked to Mark a couple of days ago, it sounds like Gabby's making incredible progress, we're just thrilled for that," the president said. "They're always in our thoughts and prayers as well. I know that's something that's been a deep concern to you as well, so I just wanted to let you know that."

"Yes sir, thank you, she's really a true inspiration to all of us," Kelly said. "I appreciate your words."

Earlier Thursday, NASA managers decided to extend Discovery's mission a second day.

The flight originally was scheduled to end March 7, but mission managers decided Monday to extend the flight by one day to give the combined crews more time to unload the PMM, launched aboard Discovery with a full load of supplies and equipment.

The astronauts also are moving packing material and no-longer-needed hardware from the PMM to a Japanese cargo ship that is scheduled to be jettisoned March 28. With Discovery in good shape, NASA managers decided Thursday to add a second docked day to the shuttle crew's timeline.

"We've just gotten official word that the MMT (Mission Management Team) has decided to go ahead and add the extra extra day so you'll have one more day on orbit," astronaut Megan McArthur radioed from Houston.

"All right, I'll pass that word along," replied Lindsey. "That's great news. We're excited."

Under the revised flight plan, Discovery will undock from the space station at 7:03 a.m. Monday, March 7. After a final heat shield inspection and routine pre-entry tests of the shuttle's flight systems, Lindsey and pilot Eric Boe plan to guide the veteran spaceplane to its final landing at the Kennedy Space Center at 11:58 a.m. on March 9.

"We're seeing a program come to a close here and to see these shuttles, these beautiful, magnificent flying machines, end their service life is obviously a little bit sad for us," astronaut Michael Barratt told an interviewer earlier Thursday. "But it is about time, they've lived a very long time, they've had a fabulous success record, they've built this magnificent space station, they've given us lots of science and a tremendous amount of experience of just how to operate in space.

"More than anything, we look forward to seeing them retire with dignity and bringing on the next line of spaceships."

NASA released spectacular footage Thursday that was captured by cameras mounted on the shuttle's twin solid-fuel boosters showing Discovery's final climb to space Feb. 24. The cameras, looking down, up and sideways at the shuttle's external tank, showed a normal ascent with no obvious signs of foam loss or damage to the ship's heat shield.

NASA managers cleared the heat shield for re-entry earlier this week, after completing a detailed review of ground-, shuttle- and space station-based photography of Discovery's protective tiles, nose cap and wing leading edge panels.

For Discovery's crew, Thursday provided a welcome half day off to relax after a busy week in orbit. The astronauts were awakened just after 5 a.m. by a recording of U2's "City of Blinding Lights" beamed up from mission control.

"Good morning, Discovery," astronaut Michael Massimino called from Houston. "That comes to you from your crewmate on the Earth, Tim Kopra. That was going to be Tim's wakeup song and he asked us to play that for you today to honor his crewmates in space."

Kopra, the Discovery mission's original lead spacewalker, was injured in a bicycle accident in Houston in January and was replaced by astronaut Stephen Bowen.

"Thanks to Tim for that," replied Lindsey. "Even though he's on the ground, he did a wonderful job supporting us during the EVAs and as he knows, he's still with us right now."

The shuttle astronauts spent their morning moving cargo to and from the International Space Station while Kelly and flight engineer Catherine Coleman serviced one of the lab's two U.S. carbon dioxide removal units.

=================================

CBS NEWS Coverage of Breaking Space News

By WILLIAM HARWOOD
CBS News

The Discovery astronauts worked through a busy half day in space Thursday, enjoyed a meal with their space station colleagues and took the afternoon off, looking forward to a call from President Barack Obama later in the day. NASA managers, meanwhile, decided to extend Discovery's mission a second day to give the crew more time to help unload a newly attached storage module.

"We've just gotten official word that the MMT (Mission Management Team) has decided to go ahead and add the extra extra day so you'll have one more day on orbit," astronaut Megan McArthur radioed from Houston.

"All right, I'll pass that word along," replied Discovery commander Steven Lindsey. "That's great news. We're excited."

Discovery's 39th and final mission originally was scheduled to end March 7, but NASA managers decided Monday to extend the flight by one day to give the combined crews more time to unload the newly attached Permanent Multipurpose Module. The PMM, the International Space Station's final U.S. pressurized module, was launched aboard Discovery loaded with supplies and equipment, including a humanoid robot known as Robonaut 2.

Along with unpacking the new supplies and equipment, the astronauts also are moving packing material and no-longer-needed hardware from the PMM to a Japanese cargo ship that is scheduled to be jettisoned March 28. With Discovery in good shape, NASA managers decided Thursday to add a second docked day to the shuttle crew's timeline.

Under the revised flight plan, Discovery will undock from the space station at 7:03 a.m. Monday, March 7. After a final heat shield inspection and routine pre-entry tests of the shuttle's flight systems, Lindsey and pilot Eric Boe plan to guide the veteran spaceplane to its final landing at the Kennedy Space Center at 11:58 a.m. on March 9.

"We're seeing a program come to a close here and to see these shuttles, these beautiful, magnificent flying machines, end their service life is obviously a little bit sad for us," astronaut Michael Barratt told an interviewer earlier Thursday. "But it is about time, they've lived a very long time, they've had a fabulous success record, they've built this magnificent space station, they've given us lots of science and a tremendous amount of experience of just how to operate in space.

"More than anything, we look forward to seeing them retire with dignity and bringing on the next line of spaceships."

NASA released spectacular footage Thursday that was captured by cameras mounted on the shuttle's twin solid-fuel boosters showing Discovery's final climb to space Feb. 24. The cameras, looking down, up and sideways at the shuttle's external tank, showed a normal ascent with no obvious signs of foam loss or damage to the ship's heat shield.

NASA managers cleared the heat shield for re-entry earlier this week, after completing a detailed review of ground-, shuttle- and space station-based photography of Discovery's protective tiles, nose cap and wing leading edge panels.

For Discovery's crew, Thursday provided a welcome half day off to relax after a busy week in orbit. The astronauts were awakened just after 5 a.m. by a recording of U2's "City of Blinding Lights" beamed up from mission control.

"Good morning, Discovery," astronaut Michael Massimino called from Houston. "That comes to you from your crewmate on the Earth, Tim Kopra. That was going to be Tim's wakeup song and he asked us to play that for you today to honor his crewmates in space."

Kopra, the Discovery mission's original lead spacewalker, was injured in a bicycle accident in Houston in January and was replaced by astronaut Stephen Bowen.

"Thanks to Tim for that," replied Lindsey. "Even though he's on the ground, he did a wonderful job supporting us during the EVAs and as he knows, he's still with us right now."

The shuttle astronauts spent their morning moving cargo to and from the International Space Station while Expedition 26 commander Scott Kelly and flight engineer Catherine Coleman serviced one of the lab's two U.S. carbon dioxide removal units.

=================================

CBS NEWS Coverage of Breaking Space News

05:25 AM, 03/03/11/10 Update: Astronauts look forward to off-duty time, presidential phone call

By WILLIAM HARWOOD
CBS News

The Discovery astronauts worked through a busy half day in space Thursday, looking forward to off-duty time and an afternoon call from President Obama.

The crew was awakened just after 5 a.m. EST (GMT-5) by a recording of U2's "City of Blinding Lights" beamed up from mission control.

"Good morning, Discovery," astronaut Michael Massimino called from Houston. "That comes to you from your crewmate on the Earth, Tim Kopra. That was going to be Tim's wakeup song and he asked us to play that for you today to honor his crewmates in space."

Kopra, the Discovery mission's original lead spacewalker, was injured in a bicycle accident in Houston in January and was replaced by astronaut Stephen Bowen.

"Thanks to Tim for that," replied Discovery commander Steven Lindsey. "Even though he's on the ground, he did a wonderful job supporting us during the EVAs and as he knows, he's still with us right now."

The shuttle astronauts planned to spend their morning moving cargo from the International Space Station's newly installed Permanent Multipurpose Module while Expedition 26 commander Scott Kelly and flight engineer Catherine Coleman planned to service one of the lab's two U.S. carbon dioxide removal units.

Two round-robin media interview sessions are planned, the first starting at 8:08 a.m. and the second at 10:33 a.m. The combined shuttle-station crews plan to enjoy a joint meal at 11:03 a.m. before taking the rest of the day off.

Video from cameras mounted on the shuttle Discovery's twin solid-fuel boosters will be aired on NASA television at 1 p.m. and replayed at 4 p.m. and 6:30 p.m.

President Barack Obama is expected to call the astronauts and cosmonauts at 5:03 p.m., followed by a mission status briefing at 6 p.m. The astronauts will go to bed at 8:23 p.m.

Here is an/10 Updated timeline of the crew's activities for flight day eight (in EST and mission elapsed time; includes rev. G of the NASA TV schedule):

DATE/EST...DD...HH...MM...EVENT

03/03
04:53 AM...06...12...00...Crew wakeup
06:38 AM...06...13...45...ISS daily planning conference
08:08 AM...06...15...15...PAO event (CNN/WTTG-TV/WTSP-TV/
..........................KNBC-TV interviews)
09:03 AM...06...16...10...Reboost config 3
10:33 AM...06...17...40...PAO event (MSNBC/WXIA-TV/
..........................Fox News Radio intervieews)
11:03 AM...06...18...10...Joint crew meal
12:03 PM...06...19...10...Shuttle crew off duty
01:00 PM...06...20...07...Solid rocket booster launch video on NTV
04:00 PM...06...23...07...Booster video replay
05:03 PM...07...00...10...Presidential phone call
05:38 PM...07...00...45...ISS daily planning conference
06:00 PM...07...01...07...Mission status briefing on NTV
06:30 PM...07...01...37...Booster video replay
07:53 PM...07...03...00...ISS crew sleep begins
08:23 PM...07...03...30...STS crew sleep begins
09:00 PM...07...04...07...Daily highlights reel (repeated hourly)

=================================

CBS NEWS Coverage of Breaking Space News

05:05 PM, 03/02/11/10 Update: Spacewalk ends

By WILLIAM HARWOOD
CBS News

Astronauts Alvin Drew and Stephen Bowen ended their second spacewalk 16 minutes early Wednesday after Drew's helmet lights came loose and could not be reattached. The six-hour 14-minute spacewalk ended at 4:56 p.m. EST (GMT-5) when the astronauts began repressurizing the International Space Station's Quest airlock module.

Despite the slightly early termination, Bowen and Drew already had accomplished all the planned objectives of the spacewalk and were working on additional "get ahead" items when Drew's helmet lights detached. Bowen attempted to reattach the unit, but he was not successful. Drew then made his way back to the airlock, followed a few minutes later by Bowen.

Working separately throughout most of the excursion, Bowen and Drew vented residual ammonia from a coolant pump scheduled for return to Earth this summer; moved an equipment platform from the Columbus lab module to the shuttle Discovery's cargo bay; installed a light on the station's solar power truss; mounted a new camera on a robot arm extension; and installed protective covers over three camera lenses.

The astronauts also repositioned a camera sunshade that had slipped out of position, removed no-longer-needed insulation and tightened up a loose fitting that is part of a coolant system repair station. Most of the spacewalk tasks were unfinished items left over from earlier spacewalks that NASA is trying to wrap up before the shuttle fleet is retired later this year.

This was the 155th spacewalk devoted to station assembly and maintenance since construction began in 1998, the fourth so far this year, the second for Drew and the seventh for Bowen. Total space station EVA time now stands at 973 hours and 53 minutes. Bowen's total -- 47 hours and 18 minutes -- moves him up to sixth on the list of most experienced spacewalkers.

=================================

CBS NEWS Coverage of Breaking Space News

10:49 AM, 03/02/11/10 Update: Spacewalk begins

By WILLIAM HARWOOD
CBS News

Floating in the Quest airlock module, astronauts Stephen Bowen and Alvin Drew switched their spacesuits to battery power at 10:42 a.m. EST (GMT-5) to officially kick off a planned six-and-a-half-hour spacewalk to perform a variety of maintenance chores outside the International Space Station.

The start of the spacewalk came 24 minutes late, primarily because of troubleshooting to replace a damaged O-ring seal in Bowen's spacesuit (see below).

Here is an/10 Updated timeline of the crew's activities based on the actual start time (in EST and spacewalk elapsed time; Bowen is EV-1; Drew is EV-2):

DATE/EST......HH...MM...EVENT

3/2
10:42:00 AM...00...00...EVA-2: Suits to battery power
10:47:00 AM...00...05...Airlock egress
11:12:00 AM...00...30...EV1: Station arm (SSRMS) setup
11:12:00 AM...00...30...EV2: Vent ops and QD bag cleanup
12:12:00 PM...01...30...EV1: Equipment platform retrieval from Columbus module
12:12:00 PM...01...30...EV2: Cargo pallet insulation removal
12:42:00 PM...02...00...EV1: Columbus platform installed in shuttle cargo bay
12:42:00 PM...02...00...EV2: Jettison stowage bag pickup
12:57:00 PM...02...15...EV2: Light install on astronaut equipment cart
01:12:00 PM...02...30...EV1: DEXTRE camera installation
01:47:00 PM...03...05...EV1: DEXTRE insulation removal
01:57:00 PM...03...15...EV2: P1 vent line insulation
02:12:00 PM...03...30...EV1: SSRMS cleanup
02:17:00 PM...03...35...EV2: P1 grapple beam troubleshooting
03:12:00 PM...04...30...EV1: SSRMS elbow camera cover install
03:27:00 PM...04...45...EV2: Node 3 insulation removal
03:27:00 PM...04...45...EV1: P1 grapple beam troubleshooting/get ahead
04:02:00 PM...05...20...EV1: DEXTRE lens cover install
04:02:00 PM...05...20...EV2: POA cover install
04:22:00 PM...05...40...Get aheads
04:42:00 PM...06...00...Cleanup and ingress
05:12:00 PM...06...30...EVA-2: Airlock repressurization

----------------------------

09:04 AM EST, 03/02/11Update: Astronauts replace damage O-ring in Bowen's spacesuit

By WILLIAM HARWOOD
CBS News

The Discovery astronauts, troubleshooting a leak in astronaut Stephen Bowen's spacesuit, briefly interrupted spacewalk preparations today to replace a damaged O-ring seal in the suit's carbon dioxide removal system.

It was not immediately clear what the problem was. After an initial leak test failed, Michael Barratt and Paolo Nespoli removed Bowen's helmet and gloves, inspected the seals and but the gear back on. The suit then failed a second leak test, prompting the astronauts to take off the helmet again and to check Bowen's boots. Again, no problems were found.

A few minutes later, Barratt reported finding a "smoking gun" -- a damaged O-ring seal in a lithium hydroxide canister used to scrub carbon dioxide from the suit's air supply. Unable to find a replacement in the airlock, the astronauts were told to use a different type O-ring instead to avoid having to open the Quest module, a procedure that would have taken a half-hour or more.

Before installing the replacement O-ring, the astronauts looked for any fragments of the original while engineers at the Johnson Space Center considered the possible impacts of debris inside the suit's air system. Barratt said no fragments could be seen, adding that the damage to the leaking O-ring did not appear fresh.

Barratt and Nespoli then re-installed the lithium hydroxide canister and carried out another leak check. This time, Bowen's suit passed.

"Good leak check," Barratt reported. "Rock solid."

The troubleshooting delayed spacewalk preparations by about 15 minutes. But the EVA remains on track to start around 10:18 a.m. EST.

=================================

CBS NEWS Coverage of Breaking Space News

07:00 AM, 03/02/11/10 Update: Astronauts gear up for second spacewalk

By WILLIAM HARWOOD
CBS News

Astronauts Alvin Drew and Stephen Bowen prepared for a final spacewalk Wednesday, a planned 6.5-hour excursion to carry out a variety of maintenance tasks outside the International Space Station.

Floating in the Quest airlock module, Drew and Bowen plan to switch their spacesuits to battery power at 10:18 a.m. EST (GMT-5) to officially begin the Discovery crew's second and final spacewalk.

For identification, Bowen, call sign EV-1, is wearing a suit with red stripes around the legs. Drew, EV-2, is wearing an unmarked suit.

This will be the 155th spacewalk devoted to station assembly and maintenance since construction began in 1998, the fourth so far this year, the second for Drew and the seventh for Bowen. Assuming the EVA runs the full six-and-a-half hours, Bowen will move up to sixth on the list of most experienced spacewalkers.

The goals of today's spacewalk are to vent residual ammonia from a failed pump module that was mounted in a storage enclosure during the crew's first spacewalk Monday; to install a camera and protective lens cover on a Canadian robot arm extension; to attach a protective lens cover to a camera on the station's robot arm; to retrieve an experiment mounting platform; to install a light on a crew equipment cart; and to conduct a variety of other maintenance tasks.

"The first order of business will be to go to the pump module, the ammonia pump that failed last summer on the space station," said space station Flight Director Chris Edelen. "That pump module was transferred on EVA-1 down to a stowage platform next to the airlock. It's being configured for return (to Earth) this summer.

"So they're going to go down to the pump module, and there is an ammonia venting line that's already been hooked up and (Drew will) throw the valve on that and vent the few pounds of residual ammonia that remain in that pump module."

To make sure no ammonia gets on the crew's spacesuits, a hose is in place "that stretches from the pump module to a point well away from either of the spacewalkers," Edelen said.

"It'll be pointed down toward the Earth so it will not be spraying anywhere near the spacewalkers. And as a final precaution, we've arranged for this activity to take place at the beginning of the EVA so if they do get inadvertently sprayed with some ammonia, there'll be time to allow that to sublimate, that's evaporation in a vacuum, so that ammonia will dissipate into space harmlessly."

The pump module is scheduled to be returned to Earth aboard the shuttle Atlantis during the final planned shuttle flight this summer.

While Drew vents the pump module, Bowen, anchored to the end of the station's robot arm, will retrieve a no-longer-needed equipment platform from the European Columbus laboratory module and move it to Discovery's cargo bay for return to Earth.

Drew, meanwhile, will remove no-longer-needed insulation on a newly installed cargo pallet on the right side of the station's power truss and install a light on a crew equipment cart mounted on the front side of the truss.

After mounting the equipment carrier in the shuttle's cargo bay, Bowen will head to the forward Harmony module where a Canadian robot arm extension, called the special purpose dexterous manipulator, or DEXTRE, is mounted.

"The crew will be installing a second camera on DEXTRE, our robot that lives on the outside of the station," Edelen said. "He has two arms and two hands that can do all kinds of external maintenance tasks and he has right now one eye on one side of his body.

"So we're going to put (on) another eye ... a camera that can pan and tilt and move around, which will give the robotics operators better visibility when they're using DEXTRE. The crew will also be installing some transparent, protective lenses over several of the cameras on our robotic arm and on DEXTRE."

Bowen also will remove no-longer-needed insulation from the robot.

A variety of other general maintenance tasks are planned, including work by Drew to tighten a loose fixture on the left side of the power truss that would be needed if a coolant system radiator needs service in the future. The excursion is scheduled to last six-and-a-half hours, followed by a mission status briefing at 7 p.m.

Here is an/10 Updated timeline of the crew's activities for flight day seven (in EST and mission elapsed time; includes rev. F of the NASA TV schedule; Bowen is EV-1 and Drew is EV-2):

DATE/EST...DD...HH...MM...EVENT

03/02
05:23 AM...05...12...30...Crew wakeup
06:03 AM...05...13...10...EVA-2: Airlock repress/hygiene break
06:43 AM...05...13...50...ISS daily planning conference
06:53 AM...05...14...00...EVA-2: Airlock depress to 10.2 psi
07:13 AM...05...14...20...EVA-2: EVA prep
08:28 AM...05...15...35...PMM 1A3 'front fence' removal
08:43 AM...05...15...50...EVA-2: Spacesuit purge
08:58 AM...05...16...05...EVA-2: Spacesuit prebreathe
09:33 AM...05...16...40...PMM vestibule CPA removal
09:48 AM...05...16...55...EVA-2: Crew lock depressurization
10:18 AM...05...17...25...EVA-2: Spacesuits to battery power
10:23 AM...05...17...30...EVA-2: Airlock egress
10:33 AM...05...17...40...Lab 1P1 ZSR relocate
10:48 AM...05...17...55...EVA-2/EV-1: Robot arm (SSRMS) setup
10:48 AM...05...17...55...EVA-2/EV-2: Vent ops/QD back C/U
11:48 AM...05...18...55...EVA-2/EV-1: Platform retrieval from Columbus
11:48 AM...05...18...55...EVA-2/EV-2: ELC-4 avionics insulation removal
12:18 PM...05...19...25...EVA-2/EV-1: Equipment platform install
12:18 PM...05...19...25...EVA-2/EV-2: Jettison stowage bag pickup
12:38 PM...05...19...45...EVA-2/EV-2: P3 CETA light install
12:48 PM...05...19...55...EVA-2/EV-1: DEXTRE camera install
01:23 PM...05...20...30...EVA-2/EV-1: DEXTRE insulation removal
01:38 PM...05...20...45...EVA-2/EV-2: Port valve module bootie install
01:48 PM...05...20...55...EVA-2/EV-1: SSRMS cleanup
01:58 PM...05...21...05...EVA-2/EV-2: P1 grapple beam troubleshooting
02:48 PM...05...21...55...EVA-2/EV-1: SSRMS elbow camera cover install
03:08 PM...05...22...15...EVA-2/EV-2: Node 3 insulation removal
03:08 PM...05...22...15...EVA-2/EV-1: P1 grapple beam troubleshooting
03:13 PM...05...22...20...PMM 1F2 fence removal
03:43 PM...05...22...50...EVA-2/EV-1: DEXTRE lens cover
03:43 PM...05...22...50...EVA-2/EV-2: POA protective cover
04:03 PM...05...23...10...EVA-2: Get aheads
04:18 PM...05...23...25...EVA-2: Cleanup and ingress
04:48 PM...05...23...55...EVA-2: Airlock repressurization
04:58 PM...06...05...00...Spacesuit servicing
06:08 PM...06...01...15...ISS daily planning conference
07:00 PM...06...02...07...Mission status briefing on NTV
08:23 PM...06...03...30...ISS crew sleep begins
08:53 PM...06...04...00...STS crew sleep begins
09:00 PM...06...04...07...Daily highlights reel (repeated hourly)

=================================

CBS NEWS Coverage of Breaking Space News

01:55 PM, 03/01/11/10 Update: Proposed Soyuz fly around of space station ruled out

By WILLIAM HARWOOD
CBS News

Russian mission managers Tuesday rejected a NASA proposal to undock a three-man Soyuz spacecraft for a fly around of the International Space Station to capture unprecedented views of the complex with the shuttle Discovery and a full complement of European, Japanese and Russian spacecraft attached.

Discovery's mission is the only time such a photograph would be possible before the shuttle fleet is retired later this summer.

"The Mission Management Team has conferred and the program's official decision is the fly about is a no-go," Stan Love radioed the shuttle-station crew from mission control, shortly after the astronauts attached a final U.S. module -- the Permanent Multipurpose Module -- to the space station. "We will keep the (one-day mission extension) for PMM outfitting and transfer to leave the station and crew in the best possible shape when Discovery undocks."

"Station copies, thanks," Expedition 26 commander Scott Kelly replied.

The fly-about proposal would have required Kelly, Soyuz commander Alexander Kaleri and Oleg Skripochka to undock from the Russian Poisk module in the Soyuz TMA-01M spacecraft. Pulling straight away from the lab complex, the Soyuz would stop and the station would change its orientation to present a good angle for photos showing the entire laboratory and all the visiting vehicles.

The Soyuz then would maneuver for a quarter-lap fly around to line back up with the Poisk module and redock with the station. The procedure was expected to take about one hour from start to finish.

But the Soyuz TMA-01M spacecraft is making its first flight with an upgraded avionics system and flight computer. Russian managers told their international counterparts today they could not go along with the fly-about proposal.

"Their primary basis was because this particular vehicle is what they consider to be a new vehicle, it's what we call a series 700 vehicle, and so this is its maiden flight," said Kenneth Todd, chairman of the space station Mission Management Team. "They had a flight program set aside for that vehicle, which had it coming to station, serving its six-month term there and then returning."

Given the short time available to assess the fly-about maneuver, along with contingency scenarios and other factors, "they came back to us and said they're recommending not doing it."

"It wasn't necessarily what we were hoping to get back, but at the same point I applaud the Russians for doing the right thing, not disregarding their own processes and making sure they do their own due diligence the way they should," Todd said. "I accepted the recommendation."

Support for the exercise was not unanimous on the U.S. side, with some engineers arguing the risks outweighed whatever benefits the unique photos would have provided.

A second Soyuz -- TMA-20 -- is docked to another port on the opposite side of the station. But that capsule's departure "cone" is very close to Discovery's vertical tail fin and Todd said NASA managers never considered using that vehicle.

Using the Soyuz TMA-01M spacecraft, thruster pluming was not an issue for Discovery because of the presence of a Japanese cargo ship just in front of the shuttle's nose that would have provided shielding.

=================================

CBS NEWS Coverage of Breaking Space News

By WILLIAM HARWOOD
CBS News

A final U.S. module was attached to the International Space Station Tuesday, an upgraded supply transfer compartment that will serve as a permanent storage closet to give station crews more room.

A few minutes after the Leonardo Permanent Multipurpose Module, or PMM, was attached to the station's central Unity module, the shuttle-station complex sailed over Italy where the new module was built by Thales Alenia Space.

"Leonardo's looking very, very happy to be in his, or her, new home," station flight engineer Catherine Coleman radioed.

"I think we should say kudos to both programs, getting the last scheduled U.S. contribution to the ... station," said Discovery astronaut Michael Barratt, a station veteran. "It's a big day for us."

The Permanent Multipurpose Module was pulled from shuttle Discovery's cargo bay starting at 8:46 a.m. EST (GMT-5). Barratt and Nicole Stott, operating the space station's robot arm, then maneuvered the module into position for attachment to Unity's Earth-facing port.

After a careful alignment, four latches pulled the 27,160-pound module snugly into place and 16 motorized bolts then were driven to firmly lock it to the station. The process was completed at 10:05 a.m.

Overnight, flight controllers tested the common berthing mechanism to make sure the big bolts would be ready for operation.

"They're each connected to a motor and they're rated to 19,000 pounds of force for each one of those," said space station Flight Director Chris Edelen. "So they're really strong. The module won't go anywhere."

Installing the PMM and preparing it for hatch opening will take most of the crew's day.

"It's a rather laborious process to get any kind of a module installed with the common berthing mechanism," Edelen said. "In addition to the task of robotically removing it from the shuttle's payload bay and installing it on the station, there's also the work to drive all those 16 bolts to get them to the right loaded force so that they securely hold the module in place, have a nice airtight seal, and then the crew has to open the hatches, perform the vestibule outfitting, the data, power and airflow connectors.

"And then finally, they have to remove some of the controllers that drive those bolts, they have to get those out of the way so there's a clear pathway. So it's quite a bit of work."

If all goes well, the PMM's hatch will be opened late today for a quick look inside.

The PMM originally was built to carry supplies and equipment to the International Space Station aboard the space shuttle and then to return to Earth with trash and no-longer-needed equipment. With the shuttle fleet scheduled for retirement after just two more missions, NASA upgraded the Leonardo MPLM for permanent attachment to the station.

The module measures 21 feet long and 15 feet wide, providing an additional 2,472 cubic feet of useable pressurized volume. While it will have power, it is intended for storage only and does not feature any crew amenities.

"This is a great example of getting your money's worth out of a product," Edelen said. "The Italians built Leonardo and the other multi-purpose logistics modules and this one has flown seven times before. ... In this case, it's going to stay up permanently.

"Obviously, with the shuttle's retirement we won't be needing logistics modules any more. Where PMM will come in handy, it'll be storage space. Right now, it's chock full of supplies, food, science gear, spare parts and Robonaut. It will be used to store all those things as well as a lot of other equipment that's... coming up on other vehicles. It'll give us extra storage space."

NASA managers decided Monday to extend Discovery's stay at the station by one day to give the crew more time to unload the PMM and configure it for orbital operations. The combined crews will remove packing materials and other launch-related components and move them to the Japanese HTV cargo ship before it is jettisoned late this month.

"A lot of the equipment in the (PMM) was packed in foam as you would expect," Edelen said. "So a lot of the foam, they're going to take that out. Now is a great time to get rid of that foam, we don't want to store that on station, it'll just contribute to our lack of stowage space that we're already battling. So that foam is going to be moved over to the Japanese HTV transfer vehicle.

"We want to get rid of any trash or foam, anything that's no longer needed in the PMM. So they'll spend a good day unpacking everything, shipping the foam over to the HTV and just tidying up the PMM."

While the PMM work is going on, astronauts Alvin Drew and Stephen Bowen will check their equipment and review their plans for a second spacewalk Wednesday. They will spend the night in the Quest airlock module at a reduced pressure to help purge nitrogen form their bloodstreams, a standard protocol to help prevent the bends.

Russian crew members plan to work on the Vozdukh carbon dioxide removal system, which has been operating intermittently in recent days. Overnight, U.S. flight controllers ran into problems with NASA's CO2 removal system when an internal heater shut down. A backup was activated and the system currently is operating at near-normal capacity.

=================================

CBS NEWS Coverage of Breaking Space News

07:55 a.m. EST, 03/01/11/10 Update: New module set for attachment to space station

By WILLIAM HARWOOD
CBS News

A final U.S. module will be attached to the International Space Station Tuesday, an upgraded supply transfer compartment that will serve as a permanent storage closet to give station crews more room.

The Italian-built Permanent Multipurpose Module, or PMM, will be pulled from the shuttle Discovery's cargo bay starting around 8:45 a.m. EST (GMT-5). Astronauts Nicole Stott and MIchael Barratt, operating the space station's robot arm, will maneuver the module into position for attachment to the Earth-facing port of the central Unity module.

Once in place, four latches will engage to pull the 27,160-pound module snugly into place. Sixteen motorized bolts then will drive to firmly lock it to the station.

Overnight, flight controllers tested the common berthing mechanism to make sure the big bolts are ready for operation.

"They're each connected to a motor and they're rated to 19,000 pounds of force for each one of those," said space station Flight Director Chris Edelen. "So they're really strong. The module won't go anywhere.

"So they checked out the drive mechanism for all those bolts, they checked out the four latches that will be used to pull it toward the sealing surface. They also deployed the petals that cover up that sealing surface and inspected that and made sure it's nice and clean, there's no debris there that can potentially interfere with a nice airtight seal."

Installing the PMM and preparing it for hatch opening will take most of the day.

"It's a rather laborious process to get any kind of a module installed with the common berthing mechanism," Edelen said. "In addition to the task of robotically removing it from the shuttle's payload bay and installing it on the station, there's also the work to drive all those 16 bolts to get them to the right loaded force so that they securely hold the module in place, have a nice airtight seal, and then the crew has to open the hatches, perform the vestibule outfitting, the data, power and airflow connectors.

"And then finally, they have to remove some of the controllers that drive those bolts, they have to get those out of the way so there's a clear pathway. So it's quite a bit of work."

If all goes well, the PMM's hatch will be opened late today for a quick look inside.

The PMM originally was built to carry supplies and equipment to the International Space Station aboard the space shuttle and then to return to Earth with trash and no-longer-needed equipment. With the shuttle fleet scheduled for retirement after just two more missions, NASA upgraded the Leonardo MPLM for permanent attachment to the station.

The module measures 21 feet long and 15 feet wide, providing an additional 2,472 cubic feet of useable pressurized volume. While it will have power, it is intended for storage only and does not feature any crew amenities.

"This is a great example of getting your money's worth out of a product," Edelen said. "The Italians built Leonardo and the other multi-purpose logistics modules and this one has flown seven times before. ... In this case, it's going to stay up permanently.

"Obviously, with the shuttle's retirement we won't be needing logistics modules any more. Where PMM will come in handy, it'll be storage space. Right now, it's chock full of supplies, food, science gear, spare parts and Robonaut. It will be used to store all those things as well as a lot of other equipment that's... coming up on other vehicles. It'll give us extra storage space."

NASA managers decided Monday to extend Discovery's stay at the station by one day to give the crew more time to unload the PMM and configure it for orbital operations. U.S. and Russian managers also are considering a plan to have a Russian Soyuz spacecraft undock for a dramatic photo survey of the station with the shuttle and a full complement of European, Japanese and Russian spacecraft attached. A decision on whether to proceed is expected later today.

Whether the Soyuz fly-around is approved or not, the mission extension will give the combined crews time to remove packing materials and other launch-related components and move them to the Japanese HTV cargo ship before it undocks late this month and burns up in the atmosphere.

"A lot of the equipment in the (PMM) was packed in foam as you would expect," Edelen said. "So a lot of the foam, they're going to take that out. Now is a great time to get rid of that foam, we don't want to store that on station, it'll just contribute to our lack of stowage space that we're already battling. So that foam is going to be moved over to the Japanese HTV transfer vehicle.

"We want to get rid of any trash or foam, anything that's no longer needed in the PMM. So they'll spend a good day unpacking everything, shipping the foam over to the HTV and just tidying up the PMM."

While the PMM attachment work is going on, astronauts Alvin Drew and Stephen Bowen will check their equipment and review their plans for a second spacewalk Wednesday. They will spend the night in the Quest airlock module at a reduced pressure to help purge nitrogen form their bloodstreams, a standard protocol to help prevent the bends.

Russian crew members plan to work on the Vozdukh carbon dioxide removal system, which has been operating intermittently in recent days. Overnight, U.S. flight controllers ran into problems with NASA's CO2 removal system when an internal heater shut down. A backup was activated and the system currently is operating at near-normal capacity.

A mission status briefing is planned for 11:30 a.m. and round-robin media interviews will begin at 4:23 p.m.

Here is an/10 Updated timeline of today's activities (in EST and mission elapsed time; includes revision E of the NASA television schedule):

DATE/EST...DD...HH...MM...SS...EVENT

03/01
05:53 AM...04...13...00...00...Crew wakeup
07:23 AM...04...14...30...00...ISS daily planning conference
08:08 AM...04...15...15...00...Station arm (SSRMS) grapples PMM
08:43 AM...04...15...50...00...SSRMS unberths PMM
09:48 AM...04...16...55...00...SSRMS intalls PMM on Unity nadir
10:18 AM...04...17...25...00...First stage bolts
10:38 AM...04...17...45...00...Second stage bolts
11:30 AM...04...18...37...00...Mission status briefing on NTV
11:38 AM...04...18...45...00...Crew meals begin
11:38 AM...04...18...45...00...SSRMS ungrapples PMM
12:38 PM...04...19...45...00...APFR heat shield removal
12:38 PM...04...19...45...00...PMM vestibule pressurization
01:53 PM...04...21...00...00...PMM vestibule ingress configured
02:33 PM...04...21...40...00...EVA-2: Equipment lock preps
02:53 PM...04...22...00...00...SSRMS positioned for EVA-2
03:18 PM...04...22...25...00...EVA-2: Tools configured
03:38 PM...04...22...45...00...Vestibule CPA removal
04:23 PM...04...23...30...00...PAO event (KING-TV/KTRK-TV/KOMO-TV)
05:08 PM...05...00...15...00...PMM IMV install
05:18 PM...05...00...25...00...EVA-2: Procedures review
06:33 PM...05...01...40...00...Vestibule CLS install
06:38 PM...05...01...45...00...ISS evening planning conference
06:58 PM...05...02...05...00...PMM ingress
07:48 PM...05...02...55...00...EVA-2: Mask pre-breathe
08:33 PM...05...03...40...00...EVA-2: Airlock depress to 10.2 psi
08:53 PM...05...04...00...00...ISS crew sleep begins
09:23 PM...05...04...30...00...STS crew sleep begins
10:00 PM...05...05...07...00...Daily highlights reel (repeated hourly)

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CBS NEWS Coverage of Breaking Space News

06:25 p.m., 02/28/11/10 Update: Shuttle mission extended one day

By WILLIAM HARWOOD
CBS News

NASA managers Monday decided to extend the shuttle Discovery's space station resupply mission by one day to give the combined crews more time to outfit a new U.S. storage module and, possibly, to stage an out-of-this-world photo opportunity.

U.S. and Russian mission managers are considering a plan that calls for a three-man Soyuz spacecraft to undock from the station for a photo fly-around to capture views of the complex with the shuttle docked, along with a full complement of visiting Russian, European and Japanese cargo ships and crew ferry craft.

Discovery's mission is the last time all of the international spacecraft will be docked at the station at the same time before the shuttle fleet is retired later this summer.

"We just wanted to let you know your plus-one docked day is approved," Stan Love radioed shuttle commander Steven Lindsey and station commander Scott Kelly. "The focus of that will be PMM (Permanent Multipurpose Module) outfitting. We are still awaiting a formal decision on the fly around. We expect that to come out of the flight day six (Tuesday) Mission Management Team meeting."

The Permanent Multipurpose Module will be attached to the Earth-facing port of the station's central Unity module early Tuesday. A new flight day 10 will be inserted into the crew's timeline for March 5.

With the mission extension, Discovery now will undock from the space station one day later, on March 6, and land back at the Kennedy Space Center around 11:35 a.m. on March 8 to close out its 39th and final mission.

This status report will be/10 Updated after an 8 p.m. EST (GMT-5) mission status briefing.

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CBS NEWS Coverage of Breaking Space News

05:30 p.m. EST, 02/28/11/10 Update: Spacewalk complete; all objectives accomplished

By WILLIAM HARWOOD
CBS News

At the end of a "textbook" spacewalk, astronauts Stephen Bowen and Alvin Drew paused before returning to the International Space Station's Quest airlock module so Drew could open a valve and "fill" a small container with the vacuum of space as part of a Japanese educational initiative.

After their crewmates played a recording of "Message in a Bottle" by the Police, Bowen grabbed a camera and with the Japanese Kibo laboratory module behind him, Drew opened the bottle to space while Bowen snapped pictures.

The astronauts then returned to the Quest airlock, closed the hatch, hooked their suits to ship power and repressurized the compartment to officially end a six-hour 34-minute spacewalk.

The spacewalk began at 10:46 a.m. EST (GMT-5) and ended at 5:20 p.m. This was the 154th spacewalk devoted to space station assembly and maintenance since construction began in 1998, pushing total EVA time to 967 hours and 39 minutes. It was the first spacewalk for Drew and the sixth for Bowen, pushing his total to 41 hours and four minutes and moving him into the top 20 on the list of most experienced spacewalkers.

The astronauts successfully installed a backup power cable for the Tranquility module, stowed a failed ammonia coolant system pump and carried out a variety of maintenance tasks ranging from insulation repairs to installation of a wedge to provide needed clearance between an external television camera and a storage platform.

"You guys did an excellent job today, you rocked," spacewalk coordinator Nicole Stott radioed from inside the shuttle-station complex.

Timothy Kopra, who was replaced by Bowen after he was injured in a bicycle accident in Houston last month, passed along his congratulations as well.

"To the whole team, great work completing a textbook EVA," he said. "And Al, congratulations for a stellar job on your first spacewalk. Good job, dude."

"Thanks, Tim, couldn't have one it without you," replied Drew, the 200th person to walk in space.

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CBS NEWS Coverage of Breaking Space News

02:50 p.m. EST, 02/28/11/10 Update: Astronauts stow failed pump module

By WILLIAM HARWOOD
CBS News

Astronauts Stephen Bowen and Alvin Drew successfully moved a 780-pound ammonia pump module from a temporary mounting point, where it was left after emergency repair work in August, to an insulated enclosure where it will remain until it's loaded aboard the shuttle Atlantis this summer for return to Earth.

Bowen, anchored to the end of the space station's robot arm, carried the boxy pump module from the forward side of the station's solar power truss to a cargo storage pallet on the Quest airlock. Assisted by Drew, Bowen slid the pump into its enclosure and the astronauts locked it in place.

A vent line was attached that will be used during a spacewalk Wednesday to release any residual ammonia trapped inside the pump.

The pump move went smoothly after an unexpected robot arm work station shut down that forced station commander Scott Kelly and Discovery astronaut Michael Barratt to switch to a spare workstation inside the Destiny laboratory module. The original work station, mounted in the multi-window cupola, later was re-activated.

With the pump module in place, the spacewalkers have accomplished the two primary objectives of the spacewalk. The astronauts now will turn their attention to a variety of maintenance tasks, including installation of a tool stanchion, insulation repair work on the upper Z1 truss segment and installation of a wedge to tilt an external camera away from a newly installed cargo pallet. If time is available, rail extensions will be added to the starboard end of a track used by the robot arm's mobile transporter.

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01:10 p.m. EST, 02/28/11/10 Update: Robot arm controls shut down; operators move to backup work station in station lab module

The robot arm workstation in the space station's multi-window cupola suddenly shut down today as spacewalker Stephen Bowen, anchored to the end of the arm, was preparing to move a large ammonia coolant pump.

Facing a half-hour reboot procedure, station commander Scott Kelly and Discovery astronaut Michael Barratt opted to move into the Destiny laboratory module where a second robot arm work station was available. The equipment and displays are identical, but operators in Destiny have to rely on television views instead of direct line of sight.

Bowen, holding onto the failed pump module, simply waited on the end of the arm while his station colleagues got the backup work station running. A few minutes past 1 p.m., arm operations resumed.

"I've got a hot-shot station crew that moved this robotic work station in a second," Barratt radioed. "So this verifies the snares are open, that Steve has the pump module, correct?

"That is correct," Stan Love replied from Houston.

"OK, we're going to be doing a five-second comm reconfig and we're going to be giving Steve a 'go.'"

While Bowen was waiting on the arm, spacewalker Alvin Drew finished installing an ammonia vent tool near the insulated enclosure that will house the pump on an external stowage platform. The tool will be used during a second spacewalk Wednesday to release any residual ammonia trapped in the pump module.

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CBS NEWS Coverage of Breaking Space News

12:00 PM, 02/28/11/10 Update: Spacewalkers install backup power cable

By WILLIAM HARWOOD
CBS News

Astronauts Stephen Bowen and Alvin Drew have successfully connected a backup power cable to the space station's Tranquility module, the first major objective of today's spacewalk.

"And Houston, I am notifying you that the J612 task is complete," spacewalk coordinator Nicole Stott radioed from orbit.

"Great job, Nicole," Timothy Kopra replied from mission control. "Good work."

Kopra was the Discovery crew's original lead spacewalker, but he was injured in a bicycle accident in Houston in January and was replaced by Bowen. Kopra is in space station mission control to provide advice and assistance as needed.

"I'm really looking forward to working with you guys ... and helping out where I can," he radioed earlier.

"It's great to hear your voice," Discovery astronaut Michael Barratt said from the station. "It's a big comfort knowing you're down there and watching over us."

"It's my pleasure."

"Thanks Tim," Bowen called from the space station's Quest airlock.

"Hey, good to hear your voice, Steve," Kopra replied.

"It should be the other way around, though," Bowen said.

"You're a good man for the job."

The J612 cable will provide power to Tranquility if the module ever has to be disconnected from the central Unity module to repair or replace a critical heat exchanger. The Discovery astronauts plan to attach a new module to the station Tuesday that will block access to the power line socket. With the cable in place, the new module can be attached and Tranquility will have backup power if it's ever needed.

The spacewalkers now are moving on to their second major task, moving an out-of-commission 800-pound ammonia coolant pump from a temporary mounting point where it was left last August after a three-spacewalk repair job to an insulated enclosure on a storage platform. The pump will remain there until it's returned to Earth aboard the shuttle Atlantis this summer.

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CBS NEWS Coverage of Breaking Space News

10:55 AM, 02/28/11/10 Update: Spacewalk begins

By WILLIAM HARWOOD
CBS News

Running 32 minutes ahead of schedule, astronauts Stephen Bowen and Alvin Drew, floating in the International Space Station's Quest airlock module, switched their spacesuits to battery power at 10:46 a.m. EST (GMT-5) to officially kick off a planned six-and-a-half-hour spacewalk.

The primary goals of the excursion are to install a backup power cable between two station modules and to move a failed ammonia coolant pump from a temporary mounting point to an insulated enclosure on an equipment stowage platform. A variety of other maintenance tasks also are planned (see the 8:10 a.m. preview story for details).

Based on the early start time for today's EVA, here's a revised timeline of the crew's activities (in EST and spacewalk elapsed time; Bowen is EV-1 and Drew is EV-2):

DATE/EST...DD...HH...MM...SS...EVENT

2/28
10:46:00 AM...00...00...00...00...EVA-1: Suits to battery power
10:51:00 AM...00...00...05...00...Egress
11:16:00 AM...00...00...30...00...J612 power cable install
11:46:00 AM...00...01...00...00...EV1: Station arm (SSRMS) setup
11:46:00 AM...00...01...00...00...EV2: Vent tool bags; foot restraint to ESP-2
12:16:00 PM...00...01...30...00...EV1: Retrieve pump module
12:16:00 PM...00...01...30...00...EV2: Vent tool setup
12:41:00 PM...00...01...55...00...EV2: Failed pump module stow
12:46:00 PM...00...02...00...00...EV1: Failed pump module install on ESP-2
02:01:00 PM...00...03...15...00...EV2: Foot restraint to Z1 truss
02:11:00 PM...00...03...25...00...EV2: Insulation repair on Z1 truss
02:16:00 PM...00...03...30...00...EV1: SSRMS cleanup
02:21:00 PM...00...03...35...00...EV2: Tool stanchion relocate
02:46:00 PM...00...04...00...00...CP3 camera wedge installation
03:46:00 PM...00...05...00...00...Get aheads: CETA rail stub;
..................................MT stop; stow tether stop
04:31:00 PM...00...05...45...00..."Message in a Bottle" educational project
04:46:00 PM...00...06...00...00...Cleanup and ingress
05:16:00 PM...00...06...30...00...EVA-1: Airlock repressurization

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CBS NEWS Coverage of Breaking Space News

08:10 AM, 02/28/11/10 Update: Astronauts suit up for spacewalk

By WILLIAM HARWOOD
CBS News

Astronauts Al Drew and Stephen Bowen are suiting up for a planned six-and-a-half-hour spacewalk to install a backup power cable between two space station modules, move a failed ammonia pump to an insulated enclosure and to perform a variety of maintenance tasks outside the orbiting lab complex. They also plan to capture a sample of the vacuum of space for a Japanese educational project called "Message in a Bottle."

Floating in the International Space Station's Quest airlock module, Bowen and Drew plan to switch their spacesuits to battery power at 11:18 a.m. EST (GMT-5) to officially begin the first of two planned excursions.

This will be the 154th spacewalk devoted to station assembly and maintenance since construction began in 1998, the third so far this year, the sixth for Bowen and the first for Drew. Going into today's spacewalk, U.S., Russian, European, Japanese and Canadian astronauts had logged 961 hours and five minutes of EVA time -- 40 days -- building and maintaining the station.

For identification, Bowen, call sign EV-1, will be wearing a suit with red stripes while Drew, call sign EV-2, will be wearing an unmarked suit.

Bowen is a late addition to Discovery's mission, joining the crew in January after lead spacewalker Timothy Kopra was injured in a bicycle accident near his home in Houston.

With only a few weeks to train, Bowen and Drew completed two full-scale dress rehearsals in NASA's giant training pool near the Johnson Space Center and reviewed procedures in the agency's virtual reality laboratory. While he received much less mission-specific training than a typical spacewalker, Bowen is a veteran of five previous EVAs and he flew on the most recent previous shuttle mission last May.

"Obviously, there are a lot of things I don't know that I'm trying to catch up (on)," he told a reporter Sunday. "But these guys have been training together for so long and they know this mission so well, they've been able to pick up the slack that I've kind of brought on board and they've got me covered pretty well."

"Plus, they put together these EVAs so well, the choreography is so clean, Tim and Al did such a fantastic job, as well as the guys on the ground."

Kopra will be in mission control at the Johnson Space Center during both of the Discovery crew's spacewalks to provide insights and advice as needed.

"We were all really sorry to hear that Tim Kopra, after his bike accident, he was not going to be able to fly," said space station Flight Director Chris Edelen. "However, the transition to Steve Bowen has been very smooth, Steve's got a lot of experience, he's done five spacewalks and in fact, he flew on the last shuttle mission back in May. And he was involved with the development of spacewalks for this flight.

"So he's perfectly suited to pick up the role. He did two practice runs for the spacewalks in the neutral buoyancy lab here in Houston, that's the large swimming pool with a mockup of the space station, so they did one dive for each of the planned spacewalks on this flight and some additional proficiency training and Steve's ready to go."

The crew's first spacewalk has two primary objectives: installation of an extension cord that must be in place before a new module is attached Tuesday; and work to move a failed 800-pound ammonia pump module that was left in a temporary location after three cooling system repair spacewalks last summer.

After exiting the airlock, Bowen and Drew will make their way to the Earth-facing side of the central Unity module where a new storage module, brought up aboard Discovery, will be attached Tuesday.

The J612 extension cable will route backup power to the Tranquility module, also known as Node 3, that is attached to Unity's left-side port. After the new Permanent Multipurpose Module, or PMM, is attached to Unity's Earth-side port, a critical heat exchanger in Tranquility will no longer be accessible for repairs if a failure occurs. The only way to fix it would be for the station's robot arm to pull the module away from Unity so spacewalking astronauts could install a replacement.

The J612 cable will provide backup power to Tranquility if such a repair is ever required.

"Just think of it as an extension cable in space," said Edelen. "There's an electrical socket on the bottom side of the (Unity) module. That socket cannot be reached once the Permanent Multipurpose Module is installed. So before we install it, we have to plug in this extension cable into the J612 connector, or socket. Then the extension cable will be hooked up to an existing cable that's already providing power to some of the airlock shell heaters. Once we get all this hooked up, the path will be cleared for installing the PMM."

With the J612 cable in place, Bowen and Drew will split up. Bowen will move up to the front of the station's solar power truss where the failed pump module is mounted on the mobile base used to transport the station's robot arm to various work sites.

The pump module failed last summer, knocking out one of the station's two cooling loops. It took the lab crew three spacewalks to remove the failed unit from the power truss and install a replacement. Because the work took longer than expected, the astronauts did not have time to move the old pump back to its normal storage location on a platform mounted on the Quest airlock.

Bowen, riding on the end of the station's robot arm, will carry the pump module to a tent-like insulated housing on External Stowage Platform No. 2 -- ESP-2 -- where the spare module that replaced it was originally mounted. Drew, meanwhile, will work to install an ammonia vent tool at the storage platform that will be used during the crew's second spacewalk Wednesday to release any ammonia that's still trapped in the pump.

If all goes well, the pump will be returned to Earth aboard the shuttle Atlantis during NASA's final planned shuttle flight this summer.

"Several months ago we had an ammonia pump for our cooling system fail on board the space station and we needed to go and replace it," Drew said in a NASA interview. "That task is very long and involved and they got the new pump in place. They got the space station in a configuration where it could sustain itself, but the old pump needed to be put away and a lot of the tools and things that were out there had to be put away, too, and next opportunity to do that was going to be during our spacewalk.

"So we will start right off with going out to pick up that failed pump and putting it back in the storage location for the replacement pump. It’s got a big tent that it goes into and we’ll put it in there and bolt it down."

With the pump module safely stowed, Bowen and Drew plan to carry out a variety of maintenance tasks, adjusting insulation on a component in the upper Z1 truss, attaching a tool stanchion and putting a wedge in place to tilt a camera away from a newly installed equipment carrier. The wedge is needed to provide additional clearance when hardware delivered aboard a Japanese cargo ship is attached later.

Before ending the spacewalk, Bowen and Drew will open a Japanese container and "fill" it with the vacuum of space in a project for the Japan Aerospace Exploration Agency calls "Message in a Bottle." According to NASA, the project is part of an on-going effort by the Japanese space agency to "create multimedia products and artistic works that inspire the general public."

"We’re simply going to open this bottle up and get a sample of the vacuum of space," Drew said. "It's a big thermos bottle and we open it up and allow it to equalize with the vacuum of space out there and then we seal it back up. ... We’ll get some photographs for the Japanese Space Agency and we'll bring that in and that would wrap up our first spacewalk."

Here is an/10 Updated timeline of the crew's activities for flight day five (in EST and mission elapsed time; includes rev. C of the NASA TV schedule):

DATE/EST...DD...HH...MM...SS...EVENT

02/28
06:23 AM...03...13...30...00...Crew wakeup
07:03 AM...03...14...10...00...EVA-1: Airlock repress/hygiene break
07:53 AM...03...15...00...00...EVA-1: Airlock depress to 10.2 psi
07:53 AM...03...15...00...00...ISS daily planning conference
09:43 AM...03...16...50...00...EVA-1: Spacesuit purge
09:58 AM...03...17...05...00...EVA-1: Spacesuit prebreathe
10:48 AM...03...17...55...00...EVA-1: Crew lock depressurization
11:18 AM...03...18...25...00...EVA-1: Spacesuits to battery power (official start time)
11:23 AM...03...18...30...00...EVA-1: Airlock egress
11:48 AM...03...18...55...00...EVA-1: J612 cable installation
12:18 PM...03...19...25...00...EVA-1/EV-1: Station arm (SSRMS) setup
12:18 PM...03...19...25...00...EVA-1/EV-2: Vent tool bags/foot restraint to ESP-2
12:48 PM...03...19...55...00...EVA-1/EV-2: Vent tool setup
12:48 PM...03...19...55...00...EVA-1/EV-1: Retrieve failed pump module
01:13 PM...03...20...20...00...EVA-1/EV-2: Failed pump stow
01:18 PM...03...20...25...00...EVA-1/EV-1: Failed pump stow
02:33 PM...03...21...40...00...EVA-1/EV-2: Foot restraint to Z1 truss
02:43 PM...03...21...50...00...EVA-1/EV-2: Z1 insulation repair
02:48 PM...03...21...55...00...EVA-1/EV-1: SSRMS cleanup
02:53 PM...03...22...00...00...EVA-1/EV-2: Tool stanchion/foot restraint
03:18 PM...03...22...25...00...EVA-1: CP3 camera wedge
04:18 PM...03...23...25...00...EVA-1: Get aheads
05:03 PM...04...00...10...00...EVA-1: Japan "Message in a Bottle"
05:18 PM...04...00...25...00...EVA-1: Cleanup and airlock ingress
05:48 PM...04...00...55...00...EVA-1: Airlock repressurization
05:58 PM...04...01...05...00...Post-EVA servicing
07:28 PM...04...02...35...00...ISS daily planning conference
08:00 PM...04...03...07...00...Mission status briefing on NTV
09:00 PM...04...04...07...00...Video File
09:23 PM...04...04...30...00...ISS crew sleep begins
09:53 PM...04...05...00...00...STS crew sleep begins
10:00 PM...04...05...07...00...Daily highlights reel (hourly)

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CBS NEWS Coverage of Breaking Space News

04:00 PM, 02/27/11: Astronauts busy with robotics, equipment transfers

By WILLIAM HARWOOD
CBS News

The Discovery astronauts worked through a busy day of robot arm activity Sunday, along with equipment transfers to the International Space Station and preparations for a spacewalk Monday by astronauts Al Drew and Stephen Bowen, the first of two planned for the shuttle's final mission.

NASA's Mission Management Team, meanwhile, concluded that a focused inspection of Discovery's heat shield will not be required later in the mission.

While the team's assessment of Discovery's overall health and readiness for re-entry is not yet complete, analysis of launch imagery and closeup photos of the shuttle's heat shield during final approach to the International Space Station Saturday show the orbiter is in good shape.

"Great news for you," astronaut Stephen Robinson radioed the crew from mission control. "No focused inspection for flight day six. That means we will replan flight day six per the way we had intended preflight, which is further outfit of the (Permanent Multipurpose Module) and maybe a little transferring, too."

"Outstanding news, Steve," shuttle commander Steven Lindsey replied.

During Discovery's launching Thursday, at least four pieces of debris could be seen falling from the shuttle's external tank, including some that appeared to hit the underside of the orbiter. But all of the events occurred after the shuttle had climbed out of the dense lower atmosphere and well beyond the timeframe when high impact velocities are a threat.

Engineers did not expect to see any damage on Discovery's heat-shield tiles and MMT Chairman LeRoy Cain told reporters Sunday the "trivial" blemishes spotted so far substantiate engineering theories about the timing of debris impacts and the likelihood of problems.

"On the entire bottom side of the orbiter, where we have thousands of tiles, we have two tiles that they looked at and the damage is just coating damage on the order of a couple of inches by a couple of inches," he said. "Just phenomenal, the performance of the entire space shuttle system to result in this kind of a report from the inspection team."

Overall, he said, "we have no areas of concern to require any kind of focused or more detailed inspection. So we won't be doing any of that."

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CBS NEWS Coverage of Breaking Space News

By WILLIAM HARWOOD
CBS News

The Discovery astronauts are working through a busy day of robot arm activity, equipment transfers to the International Space Station and making preparations for a spacewalk Monday by astronauts Al Drew and Stephen Bowen, the first of two planned for the shuttle's final mission.

The astronauts also plan to field questions from reporters in round-robin interviews starting at 2:43 p.m. EST (GMT-5). A Mission Management Team briefing is planned for 4 p.m. to review ongoing analysis of the shuttle's heat shield and other systems. But the crew was told early Sunday that a focused inspection of the heat shield will not be required later in the week, indicating no major problems have been found.

"Great news for you," astronaut Stephen Robinson radioed from mission control. "No focused inspection for flight day six. That means we will replan flight day six per the way we had intended preflight, which is further outfit of the (Permanent Multipurpose Module) and maybe a little transferring, too."

"Outstanding news, Steve," shuttle commander Steven Lindsey replied.

The crew's focus Sunday was on equipment transfers, repair work, robot arm activity and spacewalk preparations.

"We're going to be transferring some of the supplies from the shuttle middeck to the space station, putting everything away where it goes," said space station Flight Director Chris Edelen. "Also, there's a big operation (by the station crew) to remove a stuck (water) valve in the Columbus module, the European module.

"Discovery has brought up a jumper to replace that valve so (it) can be removed and brought back to Earth for inspection and eventual repair. To do that requires a rack to be rotated in Columbus and it's going to take several hours of close coordination between the crew on board as well as the European control center outside Munich."

Overnight, ground controllers moved the station's robot arm from a work site on the lab's solar power truss back to the Earth-facing side of the forward Harmony module. The arm was used Saturday to move a massive external storage platform from the shuttle to a mounting point on the underside of the truss.

"They lifted that out of the shuttle payload bay using the station's robotic arm," Edelen said. "They handed it off to the shuttle's robotic arm, repositioned the station arm so it could reach way out on the far starboard side of the station's truss, the external structure, and then they bolted ELC-4 to its permanent position where it will provide a mounting platform for external spares."

Express Logistics Carrier No. 4 was launched with a spare set of folding radiator panels for the station's ammonia cooling system. Two other items -- a cooling system rotary coupler and a box of spare electronic switching units -- will be moved to ELC-4 later. They were brought to the station by a Japanese HTV cargo ship.

But the radiator panels, which weigh 2,475 pounds and are 11 feet wide, required the shuttle.

"The space station has two large radiator wings, each made up of three separate panels, and inside these panels are tubes where liquid ammonia flows," Edelen said. "And that flows throughout the outside of the space station, it's used to cool all the electronics on space station, and it interfaces with heat exchangers for the internal module cooling as well. So a very critical part.

"If we take a micrometeoroid or orbital debris hit in one of those six panels, the ammonia could leak out. So now we have a spare radiator panel that we can install by spacewalk if that ever happens. It's good to have the spare parts on station. This is a very big piece of spare equipment and it can only fit on the space shuttle."

The station's robot arm was moved back to the Harmony module overnight for use today lifting the shuttle's heat shield inspection boom out of Discovery's payload bay. That will clear the way for removing a final U.S. module, called the Permanent Multipurpose Module, or PMM, from the cargo bay Tuesday.

The new module, loaded with supplies, science gear and an experimental humanoid robot called Robonaut, will be attached to the Earth-facing port of the station's central Unity module, providing additional long-term storage space.

Late today, Drew and Bowen will move into the station's Quest airlock module for an overnight "campout," closing the hatch and lowering the pressure to 10.2 psi to help purge nitrogen from their bloodstreams, a routine protocol for U.S. station spacewalks to help prevent the bends.

Work to mount ELC-4 got off to a late start Saturday and as a result, the Discovery astronauts were up later than originally planned. The shuttle crew was allowed to sleep an extra half hour, officially starting their day at 7:23 a.m. EST (GMT-5) with a recording of the Manhattan Transfer's "Java Jive" beamed up from mission control.

"Good morning, Discovery, and a special good morning to you, Steve Lindsey," astronaut Michael Massimino radioed from Houston.

"Good morning, Mike, and thanks to my family for that song," the shuttle commander replied. "Good to be back with you, looking forward to another good day."

Here is an/10 Updated timeline of the crew's activities for flight day four (in EST and mission elapsed time; includes rev. C of the NASA TV schedule):

DATE/EST...DD...HH...MM...SS...EVENT
02/27
07:23 AM...02...14...30...00...STS/ISS crew wakeup
08:23 AM...02...15...30...00...ISS daily planning conference
09:53 AM...02...17...00...00...Station arm (SSRMS) grapples OBSS
10:08 AM...02...17...15...00...ISS: Columbus water valve removal
10:13 AM...02...17...20...00...SSRMS unberths OBSS
10:28 AM...02...17...35...00...SSRMS moves OBSS to handoff position
10:58 AM...02...18...05...00...Shuttle arm (SRMS) grapples OBSS
11:18 AM...02...18...25...00...SSMRS ungrapples OBSS
11:43 AM...02...18...50...00...SSRMS moves from Harmony to truss
12:30 PM...02...19...37...00...Mission status briefing on NTV
12:58 PM...02...20...05...00...SSRMS moves from truss work site 3 to work site 2
01:13 PM...02...20...20...00...Spacewalk mask pre-breathe (REBA) checkout
01:43 PM...02...20...50...00...Crew meals begin
02:43 PM...02...21...50...00...Weather Channel/WBZ Radio/
...............................WSB-TV/WTVT-TV interviews
03:13 PM...02...22...20...00...ISS: PMM vestibule equipment setup
03:28 PM...02...22...35...00...EVA-1: Equipment lock preps
04:00 PM...02...23...07...00...Mission Management Team briefing on NTV
04:13 PM...02...23...20...00...EVA-1: Tools configured
05:43 PM...03...00...50...00...EVA-1: Tool audit
06:13 PM...03...01...20...00...EVA-1: Procedures review
07:38 PM...03...02...45...00...ISS daily planning conference
08:48 PM...03...03...55...00...EVA-1: Mask prebreathe/tool config
09:33 PM...03...04...40...00...EVA-1: Airlock depress to 10.2 psi
09:53 PM...03...05...00...00...ISS crew sleep begins
10:23 PM...03...05...30...00...STS crew sleep begins
11:00 PM...03...06...07...00...Daily highlights reel on NTV (repeated hourly)

=================================

CBS NEWS Coverage of Breaking Space News

By WILLIAM HARWOOD
CBS News

The shuttle Discovery glided to a picture-perfect docking with the International Space Station Saturday, the veteran spaceplane's 13th and final linkup with the orbiting outpost.

With commander Steven LIndsey manually flying Discovery from the aft flight deck, the shuttle's payload bay docking system engaged its counterpart on the front end of the station's Harmony module at 2:14 p.m. EST (GMT-5).

"Station and Houston, Discovery has capture confirmed," an astronaut radioed.

The historic linkup marked the first time in the station's 12-year history that spacecraft from the United States, Russia, the European Space Agency and Japan were docked at the outpost at the same time.

Later in the mission, if all goes well and mission managers concur, three station crew members will undock in a Russian Soyuz spacecraft to photograph the lab complex and all the visiting vehicles from afar, capturing a unique moment that, with the shuttle's looming retirement, will never be repeated.

But first, the combined crews have to complete the primary objectives of Discovery's mission, including attachment of a final U.S. module, loaded with critical supplies and equipment, and an external storage platform carrying a spare set of radiator panels.

With the shuttle attached to the station, and with all of the visiting vehicles attached, the combined shuttle-station complex masses some 1.2 million pounds. It took longer than usual for relative motion between the two spacecraft to damp out, allowing the docking mechanism to firmly lock the shuttle in place, but it wasn't immediately clear if that was due to the mass of the vehicles or some other factor.

Running about 45 minutes later than planned, a final hatch between Discovery and the station was opened at 4:16 p.m. and 20 minutes after that, Expedition 26 commander Scott Kelly, Alexander Kaleri, Oleg Skripochka, Dmitry Kondratyev, Catherine Coleman and Paolo Nespoli welcomed Lindsey and his shuttle crewmates -- pilot Eric Boe, Al Drew, Stephen Bowen, Michael Barratt and Nicole Stott -- into the space station.

After a mandatory safety briefing, the flight plan called for the shuttle astronauts to transfer spacesuits and other gear to the station.

Barratt and Stott, operating the station's robot arm, planned to pull a cargo pallet out of Discovery's cargo bay. The pallet, known as external logistics carrier No. 4, is loaded with a spare set of radiator panels for the station's ammonia cooling system.

ELC-4 will be mounted on the underside of the station's right-side solar power truss. To get it there, Barratt and Stott will hand it off to the shuttle's robot arm, operated by Boe and Drew.

The station arm then will be repositioned, inchworm fashion, moving from the Harmony module to its mobile base work station. When the move is complete, the shuttle arm will hand ELC-4 back to the station arm and the pallet will be mounted on the solar power truss for future use as needed.

Because it took longer than expected to complete the docking procedure, the actual attachment of the cargo pallet may be deferred to Sunday.

Lindsey and Boe began the terminal phase of the rendezvous at 11:33 a.m. with a rocket firing to begin closing the final 9.2 miles to the station.

Just after 1 p.m. with the shuttle poised 600 feet directly below the lab complex, Lindsey guided Discovery through a routine-but-still-spectacular end-over-end backflip maneuver, allowing the station crew to photograph the orbiter's heat shield.

Working in the Russian Zvezda command module, Coleman and Nespoli photographed Discovery's heat shield, using 400 mm and 800 mm telephoto lenses respectively, as the orbiter flipped about. The images will be downlinked to analysts in mission control at the Johnson Space Center for detailed evaluation.

During Discovery's launching Thursday, several pieces of foam insulation fell away from the ship's external tank, including some that appeared to contact the shuttle's heat shield. The foam shedding occurred well after the first two minutes and 15 seconds of flight when the dense lower atmosphere can cause debris to hit with a high relative velocity.

Engineers do not believe the foam lost Thursday caused any significant damage and nothing out of the ordinary could be seen in television views of the maneuver. But the photos taken by Coleman and Nespoli will be carefully scrutinized to make sure.

It took about 10 minutes to complete the rendezvous pitch maneuver. After that, Lindsey began moving Discovery in an arc up to a point about 300 feet directly in front of the space station with the shuttle's nose pointed toward deep space and its open payload bay facing the front end of the lab complex.

From there, Lindsey guided Discovery in to a docking at pressurize mating adapter No. 2 on the front end of the station's Harmony module.

"What took you guys so long?" Kelly joked earlier during an initial radio hookup.

"Yeah, I don't know, we kind of waited until like the last two seconds," Lindsey replied, referring to Discovery's launch Thursday in the final seconds of its window. "But it's good to hear your voice, Scott, you guys look great. We're on our way."

=================================

CBS NEWS Coverage of Breaking Space News

By WILLIAM HARWOOD
CBS News

The shuttle Discovery glided to a picture-perfect docking with the International Space Station Saturday, the veteran spaceplane's 13th and final linkup with the orbiting outpost.

With commander Steven LIndsey manually flying Discovery from the aft flight deck, the shuttle's payload bay docking system engaged its counterpart on the front end of the station's Harmony module at 2:14 p.m. EST (GMT-5).

"Station and Houston, Discovery has capture confirmed," an astronaut radioed.

The historic linkup marked the first time in the station's 12-year history that spacecraft from the United States, Russia, the European Space Agency and Japan were docked at the outpost at the same time.

Later in the mission, if all goes well and mission managers concur, three station crew members will undock in a Russian Soyuz spacecraft to photograph the lab complex and all the visiting vehicles from afar, capturing a unique moment that, with the shuttle's looming retirement, will never be repeated.

But first, the combined crews have to accomplish the primary objectives of Discovery's mission, including attachment of a final U.S. module, loaded with critical supplies and equipment, and an external storage platform carrying a spare set of radiator panels.

If all goes well, hatches between Discovery and the station will be opened shortly after 3:30 p.m. and Expedition 26 commander Scott Kelly, Alexander Kaleri, Oleg Skripochka, Dmitry Kondratyev, Catherine Coleman and Paolo Nespoli will welcome Lindsey and his shuttle crewmates -- pilot Eric Boe, Al Drew, Stephen Bowen, Michael Barratt and Nicole Stott -- into the space station.

After a mandatory safety briefing, the shuttle astronauts will get to work transferring spacesuits and other gear to the station.

Barratt and Stott, operating the station's robot arm, plan to pull a cargo pallet out of Discovery's cargo bay just before 5 p.m. The pallet, known as external logistics carrier No. 4, is loaded with a spare set of radiator panels for the station's ammonia cooling system.

ELC-4 will be mounted on the underside of the station's right-side solar power truss. To get it there, Barratt and Stott will hand it off to the shuttle's robot arm, operated by Boe and Drew.

The station arm then will be repositioned, inchworm fashion, moving from the Harmony module to its mobile base work station. When the move is complete, the shuttle arm will hand ELC-4 back to the station arm and the pallet will be mounted on the solar power truss for future use as needed.

A mission status/Mission Management Team briefing is planned for 4:30 p.m. The crew will go to bed shortly before 11 p.m.

Lindsey and Boe began the terminal phase of the rendezvous at 11:33 a.m. with a rocket firing to begin closing the final 9.2 miles to the station.

Just after 1 p.m. with the shuttle poised 600 feet directly below the lab complex, Lindsey guided Discovery through a routine-but-still-spectacular end-over-end backflip maneuver, allowing the station crew to photograph the orbiter's heat shield.

Working in the Russian Zvezda command module, Coleman and Nespoli photographed Discovery's heat shield, using 400 mm and 800 mm telephoto lenses respectively, as the orbiter flipped about. The images will be downlinked to analysts in mission control at the Johnson Space Center for detailed evaluation.

During Discovery's launching Thursday, several pieces of foam insulation fell away from the ship's external tank, including some that appeared to contact the shuttle's heat shield. The foam shedding occurred well after the first two minutes and 15 seconds of flight when the dense lower atmosphere can cause debris to hit with a high relative velocity.

Engineers do not believe the foam lost Thursday caused any significant damage and nothing out of the ordinary could be seen in television views of the maneuver. But the photos taken by Coleman and Nespoli will be carefully scrutinized to make sure.

It took about 10 minutes to complete the rendezvous pitch maneuver. After that, Lindsey began moving Discovery in an arc up to a point about 300 feet directly in front of the space station with the shuttle's nose pointed toward deep space and its open payload bay facing the front end of the lab complex.

From there, Lindsey guided Discovery in to a docking at pressurize mating adapter No. 2 on the front end of the station's Harmony module.

"What took you guys so long?" Kelly joked earlier during an initial radio hookup.

"Yeah, I don't know, we kind of waited until like the last two seconds," Lindsey replied, referring to Discovery's launch Thursday in the final seconds of its window. "But it's good to hear your voice, Scott, you guys look great. We're on our way."

=================================

CBS NEWS Coverage of Breaking Space News

08:00 AM, 02/26/11/10 Update: Shuttle Discovery closes in on space station

By William HARWOOD
CBS News Space Consultant

The shuttle Discovery closed in on the international space station early Saturday, on course for a docking around 2:16 p.m. The terminal phase of the rendezvous begins at 11:33 a.m. when commander Steven Lindsey and pilot Eric Boe fire the shuttle's maneuvering rockets to begin moving in from a point about 9.2 miles behind the space station.

A few minutes after 1 p.m., Discovery will briefly halt its approach about 600 feet directly below the space station. At that point, Lindsey will oversee a computer-assisted 360-degree back flip maneuver, exposing the shuttle's belly and critical heat-shield tiles to the crew aboard the station.

Expedition 26 flight engineers Catherine "Cady" Coleman and Paolo Nespoli will film the maneuver, using 400 mm and 800 mm telephoto lenses respectively, to capture high-resolution photographs of Discovery's heat shield tiles. The images will be downlinked to analysts in mission control at the Johnson Space Center for detailed evaluation.

During Discovery's launching Thursday, several pieces of foam insulation fell away from the ship's external tank, including some that appeared to contact the shuttle's heat shield. The foam shedding occurred well after the first two minutes and 15 seconds of flight when the dense lower atmosphere can cause debris to hit with a high relative velocity. Engineers do not believe the foam lost Thursday caused any significant damage, but the photos shot during final approach Saturday will be carefully scrutinized to make sure, and to look for anything else that might need attention.

It will take about 10 minutes to complete the rendezvous pitch maneuver. After that, Lindsey will guide Discovery in an arc up to a point about 300 feet directly in front of the space station with the shuttle's nose pointed toward deep space and its open payload bay facing the front end of the lab complex. From there, Lindsey will carefully guide Discovery in to a docking at pressurize mating adapter No. 2 on the front end of the station's Harmony module. It will be Discovery's 13th and final docking with the International Space Station.

After the docking mechanism locks the two spacecraft together, hatches will be opened shortly after 3:30 p.m. and the station crew -- Expedition 26 commander Scott Kelly, Alexander Kaleri, Oleg Skripochka, Dmitry Kondratyev, Coleman and Nespoli -- will welcome Lindsey, Boe and their shuttle crewmates -- Al Drew, Stephen Bowen, Michael Barratt and Nicole Stott -- aboard.

After a mandatory safety briefing, the shuttle astronauts will get to work transferring spacesuits and other gear to the station. Barratt and Stott, operating the station's robot arm, plan to pull a cargo pallet out of Discovery's cargo bay just before 5 p.m. The pallet, known as external logistics carrier No. 4, is loaded with a spare set of radiator panels for the station's ammonia cooling system.

ELC-4 will be mounted on the underside of the station's right-side solar power truss. To get it there, Barratt and Stott will hand it off to the shuttle's robot arm, operated by Boe and Drew. The station arm then will be repositioned, inchworm fashion, moving from the Harmony module to its mobile base work station. When the move is complete, the shuttle arm will hand ELC-4 back to the station arm and the pallet will be mounted on the solar power truss for future use as needed.

A mission status briefing is planned for 4:30 p.m. The crew will go to bed shortly before 11 p.m.

Here is an/10 Updated timeline of the crew's activities for flight day three (in EST and mission elapsed time; includes rev. C of the NASA TV schedule and an/10 Updated rendezvous timeline):

DATE/EST...DD...HH...MM...SS...EVENT

02/26
06:53 AM...01...14...00...00...STS/ISS crew wakeup
08:18 AM...01...15...25...00...Group B computer powerup
08:33 AM...01...15...40...00...Rendezvous timeline begins
08:38 AM...01...15...45...00...ISS daily planning conference
09:17 AM...01...16...24...00...NH rendeavous rocket firing
09:56 AM...01...17...03...00...NC-4 rendezvous rocket firing
11:33 AM...01...18...40...00...Ti rendezvous rocket firing
12:05 PM...01...19...11...36...ISS maneuver to docking attitude
12:07 PM...01...19...13...57...Range = 33000 ft
12:09 PM...01...19...16...02...Service module lights on
12:09 PM...01...19...16...02...Sunset
12:10 PM...01...19...16...36...ISS in docking attitude
12:13 PM...01...19...20...00...Spacesuits removed from airlock
12:32 PM...01...19...38...36...Range = 10000 ft
12:40 PM...01...19...47...16...Range = 5000 ft
12:43 PM...01...19...50...00...Begin approach timeline
12:45 PM...01...19...51...36...US solar arrays feathered
12:45 PM...01...19...51...53...Service module lights off
12:45 PM...01...19...51...53...Sunrise
12:46 PM...01...19...52...45...Range = 3000 ft
12:50 PM...01...19...56...54...MC4 rendezvous rocket firing
12:54 PM...01...20...00...54...Range = 1500 ft
12:59 PM...01...20...05...54...Range = 1000 ft
01:02 PM...01...20...08...54...KU radar to LO (800 ft)
01:03 PM...01...20...09...54...Shuttle directly below ISS (725 ft)
01:08 PM...01...20...15...06...Range = 600 ft
01:13 PM...01...20...19...46...Noon
01:15 PM...01...20...21...36...ATV solar arrays feathered
01:15 PM...01...20...21...46...Shuttle pitch maneuver start window open
01:15 PM...01...20...21...47...Start pitch maneuver
01:20 PM...01...20...26...36...ISS to proximity operations mode
01:21 PM...01...20...27...54...Pitch maneuver photo window close
01:23 PM...01...20...29...47...End pitch maneuver
01:25 PM...01...20...31...36...ISS Ku radar mask enabled
01:25 PM...01...20...32...23...Begin move to front of ISS (575 ft)
01:29 PM...01...20...36...19...Pitch maneuver start window close
01:31 PM...01...20...37...36...Russian solar arrays feathered
01:37 PM...01...20...43...53...Shuttle directly in front of ISS
01:38 PM...01...20...44...43...Range = 300 ft
01:41 PM...01...20...47...38...Sunset
01:42 PM...01...20...48...53...Range = 250 ft
01:46 PM...01...20...53...03...Range = 200 ft
01:48 PM...01...20...55...33...Range = 170 ft
01:50 PM...01...20...57...13...Range = 150 ft
01:54 PM...01...21...01...23...Range = 100 ft
01:57 PM...01...21...04...23...Range = 75 ft
02:01 PM...01...21...08...33...Range = 50 ft
02:05 PM...01...21...11...53...Range = 30 ft (start stationkeeping)
02:10 PM...01...21...16...53...End stationkeeping; push to dock
02:14 PM...01...21...21...13...Range = 10 ft

02:16 PM...01...21...22...53...DOCKING

02:16 PM...01...21...23...28...Sunrise
02:33 PM...01...21...40...00...Leak checks
03:03 PM...01...22...10...00...Group B computer powerdown
03:03 PM...01...22...10...00...Docking system prepped for ingress
03:33 PM...01...22...40...00...Hatch open
03:58 PM...01...23...05...00...Docking video playback
04:18 PM...01...23...25...00...Welcome aboard!
04:23 PM...01...23...30...00...Safety briefing
04:30 PM...01...23...37...00...Mission status/MMT briefing on NTV
04:53 PM...02...00...00...00...Station arm (SSRMS) unberths cargo pallet (ELC)
04:53 PM...02...00...00...00...EVA suits, equipment moved to ISS
05:53 PM...02...01...00...00...SSRMS hands ELC to shuttle arm (SRMS)
06:08 PM...02...01...15...00...SSRMS ungrapples ELC
06:38 PM...02...01...45...00...SSRMS walks off to MBS
07:08 PM...02...02...15...00...SRMS hands ELC back to SSRMS
07:48 PM...02...02...55...00...SSRMS ELC install
07:53 PM...02...03...00...00...ISS evening planning conference
08:33 PM...02...03...40...00...ELC-4 install
10:23 PM...02...05...30...00...ISS crew sleep begins
10:53 PM...02...06...00...00...STS crew sleep begins

=================================

CBS NEWS Coverage of Breaking Space News

10:40 PM, 02/25/11/10 Update: NASA managers assess foam debris; preliminary analysis shows no concern

By William HARWOOD
CBS News Space Consultant

NASA's Mission Management Team met briefly Friday to assess the initial progress of the shuttle Discovery's mission and review preliminary data about at least four debris "events" seen during the climb to space. It is not yet clear how many bits of debris might have hit the shuttle's heat shield, but all of the events occurred well beyond the timeframe where impacts can cause major damage.

It will take several more days to complete the initial post-launch assessment, including analysis of detailed heat shield photographs that will be taken by the International Space Station's crew during Discovery's approach to the lab complex Saturday. But for now, based on a preliminary assessment, NASA managers are not concerned.

The shuttle's external tank features two separate propellant tanks separated by a ribbed "intertank" section where the forward end of the ship's two solid-fuel boosters are attached. The lower tank holds liquid hydrogen and the upper tank holds liquid oxygen. The base of the upper liquid oxygen tank is supported by a massive flange at the top of the intertank. A similar flange at the bottom supports the top of the liquid hydrogen tank. Between the two flanges, 108 vertical stringers are used to strengthen the walls of the intertank.

Discovery blasted off Thursday after a three-and-a-half-month delay to repair cracks in the upper few inches of stringers near the oxygen tank flange and to install modifications to prevent the formation of additional, potentially dangerous stress-relief fractures.

MMT Chairman LeRoy Cain said Discovery's tank appeared to perform well during launch and that the area near the top of the intertank where the forward ends of 105 stringers were repaired or modified and refoamed had no obvious problems. But several pieces of foam debris could be seen breaking away from the lower part of the intertank, where the lower ends of the stringers meet the flange at the top of the hydrogen tank.

Based on post-Columbia analysis, engineers believe a phenomenon known as "cryopumping" can cause foam to separate from the upper area of the hydrogen tank. Air trapped in the foam first liquifies when the tank is loaded with liquid hydrogen propellant at minus 423 degrees Fahrenheit. During the climb to space, as the hydrogen level in the tank drops, the hardware warms up, the liquified air turns back into a gas and the pressure can cause overlying foam to pop off

Special care is taken during the manufacturing process to minimize the amount of trapped air that might be present in the foam, but cryopumping is a recognized -- and accepted -- risk.

"This is in an area where we know we have susceptibility to what we call cryopumping," said Cain. "That's at the very top of the liquid hydrogen tank. When we get to this three- or four-minute time period in ascent, that part of the tank is getting relatively warm compared to what it had been. And so we get this cryopumping and from a physics standpoint ... we know we can lose foam as a result of this cryopumping phenomenon. So that was, we believe preliminarily, the cause of this foam loss.

"This is an area of the tank that we're very attuned to in terms of the potential for this kind of debris loss," he said. "So we don't have any concerns about this event. Obviously, we'll do our normal vehicle inspections ... to make sure the vehicle is OK."

Debris impacts pose the greatest threat in the dense lower atmosphere, which rapidly slows lightweight foam. The accelerating shuttle can then run into the debris at a high relative velocity. After about two minutes and 15 seconds, however, atmospheric density is low enough that it no longer causes severe deceleration of the foam, resulting in much lower impact velocities.

In Discovery's case, all of the debris events occurred beyond the so called "aerodynamically sensitive transport" zone that can result in high impact velocities. The largest piece was noted around three minutes and 50 seconds after launch. It appeared to originate just above the hydrogen flange at the base of the intertank between the two bipod struts that hold the orbiter's nose to the external tank,

Cain said the timing of the releases was consistent with cryopumping and that a preliminary analysis of the camera footage indicated the debris swirled about in the zone between the tank and orbiter, possibly hitting the heat shield near the nose landing gear doors. But the impact velocity appeared to be very low and no obvious damage could be seen.

"It took sort of a random path where it initially floated up, looks like it may have touched the underside of the orbiter there in the bipod attach region and then from there, it went and traveled back along the stack and doesn't appear to have impacted any other part of the orbiter," he said.

Three other events were noted, including one that may not have been foam insulation. But they were all "well outside of the area of aerodynamic sensitive transport time and so we didn't see anything of concern in terms of debris loss from the tank," Cain said. "Overall, the performance of this tank, external tank No. 137, was really exceptional."

The entire underside of the shuttle will be photographed with 400-mm and 800-mm telephoto lenses during Discovery's approach to the space station Saturday. If any problem areas are spotted, the shuttle crew can carry out a "focused inspection" later in the mission to collect additional data.

NASA hopes to launch the shuttle Endeavour April 19 on its final flight. Endeavour's external tank has been modified like Discovery's to strengthen the stringers near the upper oxygen tank flange. Cain said as of now, he doubts any changes will be ordered for Endeavour's tank based on the results of Discovery's launch. But no final decisions will be made until engineers complete their post-launch assessment.

"I do not anticipate that what we've seen in terms of performance on this tank would cause us to want to do anything different in the area of the LH2 flange on the upcoming two tanks," Cain said. "In fact, I would say, contrary to that, I think we'll look at the performance of this tank once all the data (are) in and it'll confirm what we think today, which is it performed exceptionally and it reinforces the modifications we did on the (liquid oxygen) flange area. So I think it'll reinforce the flight rationale we established to go fly this mission."

=================================

CBS NEWS Coverage of Breaking Space News

By WILLIAM HARWOOD
CBS News

Astronaut Timothy Kopra, who was replaced on the shuttle Discovery's crew after being injured in a bicycle accident last month, called his former crewmates Friday to say hello and pass along best wishes for a successful mission.

"Hey Steve, (this is) Tim, I just wanted to tell you guys you all had an awesome launch and we're all very proud of you down here," Kopra radioed from mission control at the Johnson Space Center in Houston.

"Great to hear your voice, Tim, I wish you were here because I'd send you on the hunt for the overlay I'm missing," Discovery commander Steven Lindsey replied. He was joking about a computer screen overlay used for robot arm heat shield inspections. "But anyway, I appreciate the good words, it was a great launch. I can't tell you how much we wish you were here with us as well."

"Well, I'm sure you know I feel the same way," Kopra said, "so I definitely feel like I'm there in spirit and I'm especially looking forward to seeing Steve and Al go out the door and do great work."

Kopra was the mission's flight engineer and lead spacewalker, helping plan two EVAs with crewmate Al Drew. Kopra was replaced by Stephen Bowen, a veteran spacewalker who flew on the most recent previous shuttle mission. Kopra will be available during the upcoming spacewalks to offer advice and insights based on more than a year training for the mission.

"Hi, Timmy," astronaut Nicole Stott called down. "I just want to say I love you and like Steve said, we wish you were here, but we're also very happy you'll be supporting us from the ground and I look forward to talking to you on EVA days."

"Love you back and it's going to be a great couple of EVAs," Kopra said.

Kopra, Stott and Discovery crewmate Michael Barratt are veterans of long-duration stays aboard the International Space Station.

"Hey Tim, it's Mike," Barratt radioed. "We've missed your booming zero G laughter up here and I'll have to tell you, you're here in a little bit more than spirit, but we'll have to explain that when we get back."

"I'm looking forward to that, Mike, it's great to hear your voice," Kopra said.

"All right, man, you keep watching us and we'll try to do our best for you ... with the plan that you came up with."

Steven Robinson, the mission control shuttle communicator, closed the conversation by saying "All right, Discovery, just goes to show you have a seven-person crew, they're just not all up there with you."

The Discovery astronauts were awakened for their first full day in space at 6:53 a.m. EST (GMT-5) Friday by a recording of "Through Heaven's Eyes" from the movie "Prince of Egypt" that was beamed up from mission control for Barratt.

"That comes with a very special hello from Mike's family," astronaut Michael Massimino radioed from Houston.

"Good morning, Mike, and thanks to my crazy, wonderful family," Barratt replied. "It's great to be back in space again. I wish everyone could see through my eyes up here, too. Look forward to working with you today."

The astronauts faced a routine but busy day in orbit highlighted by a close inspection of the shuttle reinforced carbon carbon nose cap and wing leading edge panels, which experience the most extreme heating during re-entry.

Using a camera/laser scanner on the end of a 50-foot-long boom attached to the shuttle's robot arm, Lindsey, Drew and pilot Eric Boe looked for any signs of damage from ascent debris impacts, staring with the right wing, followed by the nose cap and then the left wing. The data will be downlinked to analysts at the Johnson Space Center in Houston later this evening by Stott.

Drew, Barratt and Bowen plan to inspect and check out the spacesuits Drew and Bowen will use during two space station EVAs and prepare the suits for transfer to the space station. Two rendezvous rocket firings are planned to fine tune Discovery's approach to the space station.

Docking at the lab's forward port is planned for 2:15:54 p.m. EST Saturday. The astronauts will break out their rendezvous tools later today and rig the ship's docking system for capture (an/10 Updated rendezvous timeline is posted on the Flight Data File page).

A mission status/Mission Management Team briefing is planned for 4:30 p.m. The crew will go to bed just before 11 p.m.

Here is an/10 Updated timeline of the crew's activities for flight day two (in EST and mission elapsed time; includes rev. B of the NASA TV schedule):

DATE/EST...DD...HH...MM...SS...EVENT

02/25
06:53 AM...00...14...00...00...Crew wakeup
08:58 AM...00...16...05...00...Minicam downlink
09:49 AM...00...16...55...56...NC-2 rendezvous rocket firing
09:53 AM...00...17...00...00...Shuttle arm (SRMS) unberths inspection boom (OBSS)
10:33 AM...00...17...40...00...AEM video
11:08 AM...00...18...15...00...OBSS starboard wing survey
11:08 AM...00...18...15...00...Ergometer setup
11:38 AM...00...18...45...00...Middeck transfer preps
01:03 PM...00...20...10...00...OBSS nose cap survey
01:48 PM...00...20...55...00...Crew meals begin
02:48 PM...00...21...55...00...OMS pod survey
02:53 PM...00...22...00...00...Spacesuit checkout preps
03:18 PM...00...22...25...00...OBSS port wing survey
03:23 PM...00...22...30...00...Spacesuit checkout
04:30 PM...00...23...37...00...Mission status/MMT briefing
04:53 PM...01...00...00...00...SRMS berths OBSS
05:08 PM...01...00...15...00...EVA equipment prep for transfer
05:58 PM...01...01...05...00...Centerline camera setup
06:28 PM...01...01...35...00...Orbiter docking system ring extension
06:48 PM...01...01...55...00...Rendezvous tools checkout
08:03 PM...01...03...10...06...NC-3 rendezvous rocket firing
07:28 PM...01...02...35...00...LDRI downlink
10:53 PM...01...06...00...00...Crew sleep begins
11:00 PM...01...06...07...00...Daily highlights reel on NTV

=================================

CBS NEWS Coverage of Breaking Space News

07:35 AM, 02/25/11/10 Update: Shuttle crew gears up for nose cap, wing inspections; rendezvous preps

By William HARWOOD
CBS News Space Consultant

The Discovery astronauts were awakened for their first full day in space at 6:53 a.m. EST (GMT-5) Friday by a recording of "Through Heaven's Eyes" from the movie "Prince of Egypt" that was beamed up from mission control for astronaut Michael Barratt.

"That comes with a very special hello from Mike's family," astronaut Michael Massimino radioed from Houston.

"Good morning, Mike, and thanks to my crazy, wonderful family," Barratt replied. "It's great to be back in space again. I wish everyone could see through my eyes up here, too. Look forward to working with you today."

The astronauts face a routine but busy day in orbit highlighted by a close inspection of the shuttle reinforced carbon carbon nose cap and wing leading edge panels, which experience the most extreme heating during re-entry.

Using a camera/laser scanner on the end of a 50-foot-long boom attached to the shuttle's robot arm, commander Steven Lindsey, pilot Eric Boe and Al Drew will look for any signs of damage from ascent debris impacts, staring with the right wing, followed by the nose cap and then the left wing. The data will be downlinked to analysts at the Johnson Space Center in Houston later this evening by astronaut Nicole Stott.

Drew, Barratt and Stephen Bowen plan to inspect and check out the spacesuits Drew and Bowen will use during two space station EVAs and prepare the suits for transfer to the space station. Two rendezvous rocket firings are planned to fine tune Discovery's approach to the space station.

Docking at the lab's forward port is planned for 2:15:54 p.m. EST Saturday. The astronauts will break out their rendezvous tools later today and rig the ship's docking system for capture (an/10 Updated rendezvous timeline is posted on the Flight Data File page).

A mission status/Mission Management Team briefing is planned for 4:30 p.m. The crew will go to bed just before 11 p.m.

Here is an/10 Updated timeline of the crew's activities for flight day two (in EST and mission elapsed time; includes rev. B of the NASA TV schedule):

DATE/EST...DD...HH...MM...SS...EVENT

02/25
06:53 AM...00...14...00...00...Crew wakeup
08:58 AM...00...16...05...00...Minicam downlink
09:49 AM...00...16...55...56...NC-2 rendezvous rocket firing
09:53 AM...00...17...00...00...Shuttle arm unberths inspection boom (OBSS)
10:33 AM...00...17...40...00...AEM video
11:08 AM...00...18...15...00...OBSS starboard wing survey
11:08 AM...00...18...15...00...Ergometer setup
11:38 AM...00...18...45...00...Middeck transfer preps
01:03 PM...00...20...10...00...OBSS nose cap survey
01:48 PM...00...20...55...00...Crew meals begin
02:48 PM...00...21...55...00...OMS pod survey
02:53 PM...00...22...00...00...Spacesuit checkout preps
03:18 PM...00...22...25...00...OBSS port wing survey
03:23 PM...00...22...30...00...Spacesuit checkout
04:30 PM...00...23...37...00...Mission status/MMT briefing
04:53 PM...01...00...00...00...Shuttle arm berths OBSS
05:08 PM...01...00...15...00...EVA equipment prep for transfer
05:58 PM...01...01...05...00...Centerline camera setup
06:28 PM...01...01...35...00...Orbiter docking system ring extension
06:48 PM...01...01...55...00...Rendezvous tools checkout
08:03 PM...01...03...10...06...NC-3 rendezvous rocket firing
07:28 PM...01...02...35...00...LDRI downlink
10:53 PM...01...06...00...00...Crew sleep begins
11:00 PM...01...06...07...00...Daily highlights reel on NTV

=================================

CBS NEWS Coverage of Breaking Space News

By William HARWOOD
CBS News Space Consultant

After a last-minute Air Force computer glitch that threatened to derail launch, the shuttle Discovery, carrying an all-veteran crew of six, critical supplies and a final U.S. module for the International Space Station, blasted off with seconds to spare and vaulted into orbit Thursday to begin its 39th and final flight.

Several relatively large pieces of foam insulation appeared to fall away from the shuttle's repaired external tank, including some that hit the ship's heat shield. But the observed impacts occurred well after the shuttle was out of the dense lower atmosphere where debris impacts pose the greatest threat.

No obvious heat shield damage could be seen, but engineers will carry out a detailed analysis over the next several days to make sure.

Discovery's crew, running three-and-a-half months behind schedule because of work to address cracks in the shuttle's external tank cracks, strapped in just after 1:03 p.m. EST (GMT-to await liftoff at 4:50:27 p.m., roughly the moment Earth's rotation carried the launch pad into the plane of the space station's orbit.

But trouble with an Air Force range safety system computer put the launch in doubt as the countdown ticked into its final minutes. With the end of Discovery's short three-minute launch window approaching, Launch Director Mike Leinbach ordered engineers to pick up the countdown at the T-minus nine-minute mark and to press ahead in hopes the Air Force would be ready in time.

But the problem was not immediately resolved and the countdown entered an unplanned "hold" at the T-minus five-minute mark. Finally, with time running out, the glitch was resolved, the countdown resumed and Discovery blasted off at 4:53:24 p.m., just three seconds before the end of the available launch window.

""Well, it was kind of an exciting last few minutes of this countdown," Leinbach told reporters later. "Several of us have been around for many, many countdowns and this was one for the record books. ... This was Discovery's last (launch), a great way to go out. She gave us a little bit of a fit today, but it's a great way to get (commander) Steve Lindsey and his crew on orbit. I'm very, very proud of my launch team and all the rest of the people who worked so hard on Discovery."

Large crowds gathered along area roads and beaches to witness Discovery's final climb to space and the shuttle did not disappoint, putting on a dramatic show as it climbed away through a mostly clear sky.

Because of the tank repairs and extensive re-application of protective foam insulation, flight controllers were on the lookout for any signs of foam debris falling away from the tank during the first minute and a half of flight when the dense lower atmosphere can cause debris to hit the shuttle with a high relative velocity.

Live television views from a camera mounted on the side of the tank showed several relatively large pieces of debris, presumably foam, separating and falling away roughly four minutes after launch

The most aerodynamically dangerous period from a debris impact standpoint is the first two minutes and 15 seconds of flight. While several pieces appeared to hit Discovery's heat shield, no obvious signs of impact damage could be seen.

"We did see some foam losses that did occur," astronaut Charles Hobaugh radioed the crew later. "The primary one was noted right around four minutes, three minutes and 55 seconds. The time we have the most concern about is two fifteen, so it was well after that. Currently, we have no concerns for the vehicle or success. We'll find out more, of course, as we go through the ascent video with a finer tooth comb and also after we do the surveys. So we're looking forward to all that."

"OK, copy that," Lindsey replied. "So that foam loss that they saw was after (the aerodynamically sensitive regime)?"

"That is correct," Hobaugh replied. "About a minute and 40 seconds later."

"OK, great.."

Bill Gerstenmaier, director of space operations at NASA headquarters, said the timing of the releases was consistent with an understood phenomenon known as "cryopumping." Such debris typically comes from the upper regions of the hydrogen tank, the result of trapped air in the foam expanding as the tank empties and warms up, causing overlying foam to pop off.

Gerstenmaier said a quick look at the ascent video indicated the repaired areas of foam near the top of the intertank stayed in place.

"From the cursory look at what we saw today and what we saw in the ascent video, I think it's consistent with our experience base," he said. "The loss, although the size is fairly large, the mass is not very much of a concern to us and the fact that it's late and it's kind of an understood timing consideration doesn't cause us a lot of concern. But that doesn't mean we won't keep digging and looking and trying to understand."

Joining Lindsey on the shuttle's flight deck were pilot Eric Boe, ascent flight engineer Al Drew and astronaut Nicole Stott, a space station veteran. Physician-astronaut Michael Barratt and Stephen Bowen, a former Navy submariner, were strapped in on the shuttle's lower deck.

A veteran of two previous shuttle flights, Bowen joined Discovery's crew in January after Timothy Kopra, the mission's original flight engineer and lead spacewalker, was injured in a bicycle mishap near his home in Houston.

"It was actually a sad story," Bowen said in a NASA interview. "Tim had worked for well over a year putting this thing together and had an accident. He's unable to make the launch time frame (and) we needed to find somebody to fill his role. ... It was not what you expected, not what you want. Tim worked really hard."

Kopra plans to help out in mission control during the flight, providing advice as needed based on his extensive training experience.

The primary goals of the 133rd shuttle mission are to deliver critical spare parts, supplies and a U.S. storage module to the International Space Station as NASA completes the lab's assembly more than 12 years after construction began in 1998.

Only two more shuttle flights are planned, one by Endeavour in April and a final mission by Atlantis in late June, before all three of NASA's orbiters are decommissioned and turned into museum displays. A decision on where the shuttles will end up is expected later this year.

"Discovery's a workhorse, the fleet leader in number of flights, done a lot of famous flights, all the return-to-flight test missions," Lindsey said before the crew's initial launch attempt. "Yet when you walk inside Discovery, it still looks like a new car even after almost 30 years of service. It's a great machine, a great vehicle. It's a privilege for us to be able to fly it on the last flight."

For Leinbach, the end of the line for Discovery will come on the Kennedy Space Center runway when it rolls to a stop after its 13th and final mission to the space station.

"Landing day's going to be tough," he said. "Landing day of Discovery, and then Endeavour and especially Atlantis, the last mission, you'll see a lot of people on the runway who will probably choke up some. Because it's the end of a 30-year program that not only have we worked in and made our livelihoods in but we've grown to love and appreciate and feel like we're doing something special for the country and, really, the world."

He said Discovery is "a great ship. This is her 39th mission, we'd have quite a few left in her had the program been extended. But it wasn't, and so it's kind of bittersweet to get the last flight out of her. But she's going to perform perfectly fine on orbit and bring the crew home safely."

With it's on-time launch, Lindsey and Boe plan to oversee a two-day rendezvous with the space station. The crew will carry out a now-routine heat-shield inspection Friday before guiding the shuttle to a docking at the station's forward port around 2:16 p.m. Saturday.

Waiting to welcome the shuttle astronauts aboard will be Expedition 26 commander Scott Kelly, Alexander Kaleri, Oleg Skripochka, Catherine Coleman, Dmitry Kondratyev and Italian astronaut Paolo Nespoli.

Discovery is scheduled to spend seven days docked to the space station, departing on March 5 and landing back at the Kennedy Space Center around 12:45 p.m. on March 7.

But U.S. and Russian space managers are expected to approve a one-day mission extension for an out-of-this-world photo opportunity.

The idea is to insert a new flight day 10 in the crew's timeline -- March 5 -- so Kelly, Kaleri and Skripochka can undock in the Soyuz TMA-01M spacecraft and photograph the space station with the shuttle and a full complement of European, Japanese and Russian cargo ships and crew capsules attached.

Discovery's mission is the last time all of the international spacecraft will be docked at the station at the same time before the shuttle fleet is retired later this summer.

Assuming the fly-around is approved -- and no decisions are expected until after Discovery reaches the space station -- Discovery would undock on March 6 and land in Florida around 11:35 a.m. on March 8.

NASA originally hoped to launch Discovery in November, but in the wake of a Nov. 5 launch delay engineers discovered small cracks in vertical rib-like stringers used in the wall of the external tank's central "intertank" section.

The cracks were repaired, but work to understand what caused their formation required exhaustive tests and analyses. The analysis had to address two major questions: issues: the structural integrity of the tank and the likelihood of small cracks to cause foam insulation to pop off during ascent.

Engineers ultimately concluded the cracks were caused by temperature-induced stress near the tops of the stringers as the upper liquid oxygen tank, exposed to minus 297-degree propellant, contracted during fuel loading. That contraction causes the tops of the stringers to pull inward.

The tank is designed to accommodate that contraction, but a manufacturing review found that the aluminum-lithium alloy used in the stringers was from a lot that was more brittle than usual and more susceptible to fractures.

To provide additional strength, so-called "radius-block doublers" were riveted into place over the top few inches of 105 of the 108 stringers used in the intertank section to make them less susceptible to stress-relief fractures.

=================================

CBS NEWS Coverage of Breaking Space News

5:55 PM, 02/24/11/10 Update: Shuttle Discovery rockets into space on final voyage

By William HARWOOD
CBS News Space Consultant

After a last-minute Air Force computer glitch that threatened to derail launch, the shuttle Discovery, carrying an all-veteran crew of six, critical supplies and a final U.S. module for the International Space Station, blasted off and vaulted into orbit Thursday to begin its 39th and final flight.

Several relatively large pieces of foam insulation appeared to fall away from the shuttle's repaired external tank, including some that hit the ship's heat shield. But the observed impacts occurred well after the shuttle was out of the dense lower atmosphere where debris impacts pose the greatest threat. No obvious heat shield damage could be seen, but engineers will carry out a detailed analysis over the next several days to make sure.

Discovery's crew, running three-and-a-half months behind schedule because of work to address cracks in the shuttle's external tank cracks, strapped in just after 1:03 p.m. EST (GMT-to await liftoff at 4:50:27 p.m., roughly the moment Earth's rotation carried the launch pad into the plane of the space station's orbit. The launching

But trouble with an Air Force range safety system computer put the launch in doubt as the countdown ticked into its final stages. To give repair crews as much time as possible, Launch Director Mike Leinbach ordered engineers to pick up the countdown at the T-minus nine-minute mark and to press ahead toward launch.

But the problem was not immediately resolved and the countdown entered an unplanned "hold" at the T-minus five-minute mark. Finally, with just three seconds left to make the end of the launch window, the glitch was resolved, the countdown resumed and Discovery blasted off at 4:53:24 p.m.

Riding a torrent of 5,000-degree flame, Discovery majestically accelerated skyward, wheeling about its long axis and lining up on a trajectory paralleling the East Coast of the United States. By launching directly into the plane of the space station's orbit, Discovery will be able to catch up with the lab complex for a docking Saturday.

Large crowds gathered along area roads and beaches to witness Discovery's final climb to space and the shuttle did not disappoint, putting on a dramatic show as it climbed away through a mostly clear sky.

Because of the tank repairs and extensive re-application of protective foam insulation, flight controllers were on the lookout for any signs of foam debris falling away from the tank during the first minute and a half of flight when the dense lower atmosphere can cause debris to hit the shuttle with a high relative velocity.

Live television views from a camera mounted on the side of the tank showed several relatively large pieces of debris, presumably foam, separating and falling away several minutes after liftoff. But that was well after the most aerodynamically dangerous period of flight and while several pieces appeared to hit Discovery's heat shield, no obvious signs of impact damage could be seen.

As always, engineers will carry out a detailed analysis over the next several days to determine what, if any, damage the foam might have caused to the shuttle's heat shield.

Engineers also will assess what impact the foam losses might have on plans to launch the shuttle Endeavour April 19 on another space station mission. Endeavour's tank underwent the same invasive tank repairs as Discovery's and problems with foam adhesion could prompt additional troubleshooting.

At the controls aboard Discovery were commander Steven Lindsey, pilot Eric Boe and ascent flight engineer Al Drew. Astronaut Nicole Stott, a space station veteran, was seated to Drew's right while physician-astronaut Michael Barratt and Stephen Bowen, a former Navy submariner, were strapped in on the shuttle's lower deck.

A veteran of two previous shuttle flights, Bowen joined Discovery's crew in January after Timothy Kopra, the mission's original flight engineer and lead spacewalker, was injured in a bicycle mishap near his home in Houston.

"It was actually a sad story," Bowen said in a NASA interview. "Tim had worked for well over a year putting this thing together and had an accident. He's unable to make the launch time frame (and) we needed to find somebody to fill his role. ... It was not what you expected, not what you want. Tim worked really hard."

Kopra plans to help out in mission control during the flight, providing advice as needed based on his extensive training experience.

The primary goals of the 133rd shuttle mission are to deliver critical spare parts, supplies and a U.S. storage module to the International Space Station as NASA completes the lab's assembly more than 12 years after construction began in 1998.

Only two more shuttle flights are planned, one by Endeavour in April and a final mission by Atlantis in late June, before all three of NASA's orbiters are decommissioned and turned into museum displays. A decision on where the shuttles will end up is expected later this year.

"Discovery's a workhorse, the fleet leader in number of flights, done a lot of famous flights, all the return-to-flight test missions," Lindsey said before the crew's initial launch attempt. "Yet when you walk inside Discovery, it still looks like a new car even after almost 30 years of service. It's a great machine, a great vehicle. It's a privilege for us to be able to fly it on the last flight."

For Launch Director Mike Leinbach, the end of the line for Discovery will come on the Kennedy Space Center runway when it rolls to a stop after its 13th and final mission to the space station.

"Landing day's going to be tough," he said. "Landing day of Discovery, and then Endeavour and especially Atlantis, the last mission, you'll see a lot of people on the runway who will probably choke up some. Because it's the end of a 30-year program that not only have we worked in and made our livelihoods in but we've grown to love and appreciate and feel like we're doing something special for the country and, really, the world."

He said Discovery is "a great ship. This is her 39th mission, we'd have quite a few left in her had the program been extended. But it wasn't, and so it's kind of bittersweet to get the last flight out of her. But she's going to perform perfectly fine on orbit and bring the crew home safely."

With it's on-time launch, Lindsey and Boe plan to oversee a two-day rendezvous with the space station. The crew will carry out a now-routine heat-shield inspection Friday before guiding the shuttle to a docking at the station's forward port around 2:16 p.m. Saturday.

Waiting to welcome the shuttle astronauts aboard will be Expedition 26 commander Scott Kelly, Alexander Kaleri, Oleg Skripochka, Catherine Coleman, Dmitry Kondratyev and Italian astronaut Paolo Nespoli.

Discovery is scheduled to spend seven days docked to the space station, departing on March 5 and landing back at the Kennedy Space Center around 12:45 p.m. on March 7.

But U.S. and Russian space managers are expected to approve a one-day mission extension for an out-of-this-world photo opportunity.

The idea is to insert a new flight day 10 in the crew's timeline -- March 5 -- so Kelly, Kaleri and Skripochka can undock in the Soyuz TMA-01M spacecraft and photograph the space station with the shuttle and a full complement of European, Japanese and Russian cargo ships and crew capsules attached.

Discovery's mission is the last time all of the international spacecraft will be docked at the station at the same time before the shuttle fleet is retired later this summer.

Assuming the fly-around is approved -- and no decisions are expected until after Discovery reaches the space station -- Discovery would undock on March 6 and land in Florida around 11:35 a.m. on March 8.

NASA originally hoped to launch Discovery in November, but in the wake of a Nov. 5 launch delay engineers discovered small cracks in vertical rib-like stringers used in the wall of the external tank's central "intertank" section.

The cracks were repaired, but work to understand what caused their formation required exhaustive tests and analyses. The analysis had to address two major questions: issues: the structural integrity of the tank and the likelihood of small cracks to cause foam insulation to pop off during ascent.

Engineers ultimately concluded the cracks were caused by temperature-induced stress near the tops of the stringers as the upper liquid oxygen tank, exposed to minus 297-degree propellant, contracted during fuel loading. That contraction causes the tops of the stringers to pull inward.

The tank is designed to accommodate that contraction, but a manufacturing review found that the aluminum-lithium alloy used in the stringers was from a lot that was more brittle than usual and more susceptible to fractures.

To provide additional strength, so-called "radius-block doublers" were riveted into place over the top few inches of 105 of the 108 stringers used in the intertank section to make them less susceptible to stress-relief fractures.

=================================

CBS NEWS Coverage of Breaking Space News

11:05 AM, 02/24/11/10 Update: European cargo ship docks with space station

By William HARWOOD
CBS News Space Consultant

An unmanned European cargo ship carrying more than seven tons of supplies and equipment successfully docked with the International Space Station Thursday after an automated approach.

Approaching from directly behind the lab complex, the Automated Transfer Vehicle 2 glided to a slow-motion docking at the Zvezda command module's aft port at 10:59 a.m. EST (GMT-5) as the two spacecraft were sailing 220 miles above the central Atlantic Ocean.

If all goes well, the shuttle Discovery, scheduled for launch from the Kennedy Space Center at 4:50 p.m. Thursday, will dock at the forward end of the space station on Saturday. It will be the first time in the station's 12-year history that spacecraft from the United States, Russia, Japan and the European Space Agency have been docked at the outpost at the same time.

Assuming Discovery's mission goes well, three station crew members plan to undock in a Russian Soyuz spacecraft before the shuttle departs to photograph the station with the full complement of visiting vehicles.

The ATV-2 is loaded with more than 3,086 pounds of dry cargo in its forward pressurized section, including 1,316 pounds of vehicle hardware, 1,402 pounds of crew supplies, 212 pounds of science equipment and another 160 pounds of spacewalk gear and laptop computers.

The cargo ship also is carrying 220 pounds of gaseous oxygen, 1,874 pounds of propellant that will be pumped aboard the space station and another 8,818 pounds of propellant for boosting the station's orbit during 101 days of docked operations.

=================================

CBS NEWS Coverage of Breaking Space News

10:55 AM, 02/24/11/10 Update: Shuttle fueling complete; countdown proceeding smoothly

By William HARWOOD
CBS News Space Consultant

The shuttle Discovery's external tank has been loaded with more than a half-million gallons of liquid oxygen and hydrogen rocket fuel. The fueling procedure began at 7:25 a.m. EST (GMT-5) and was declared complete at 10:19 a.m.

The tank is now in "stable replenish" mode and NASA's final inspection team is carrying out a launch pad walk down to look for any signs of debris or other problems that could cause trouble. There are no known issues and forecasters are continuing to predict a 90 percent chance of acceptable weather.

=================================

CBS NEWS Coverage of Breaking Space News

9:40 AM, 02/24/11/10 Update: Hydrogen vent line working normally

By William HARWOOD
CBS News Space Consultant

Fueling of the shuttle Discovery is proceeding smoothly at pad 39A. There are no technical problems of any significance and engineers say a 7-inch gaseous hydrogen vent line that leaked Nov. 5, triggering Discovery's most recent launch delay, appears to be working normally today.

The vent line is needed because some of the liquid hydrogen inside the tank turns into a gas that must be carried away to maintain the proper internal pressure. The vent line attaches to the side of the tank at a ground umbilical carrier plate, or GUCP, that features a large quick-disconnect fitting.

During a launch attempt Nov. 5, a significant leak was observed as the tank filled and the vent line was exposed to ultra low temperatures. Similar leaks delayed two earlier shuttle missions.

Extensive troubleshooting showed leaks can occur because of slight alignment errors in the quick-disconnect hardware, errors that only cause a problem when the metal is exposed to the low temperatures experienced during fueling. Engineers revised their installation procedures to ensure a proper alignment and the system worked normally during a fueling test in December.

While the vent line leak last November triggered Discovery's most recent actual launch delay, the flight has been on hold since then because of unrelated cracks in the shuttle's external tank. The cracks were repaired and the tank was modified to prevent any additional stress-relief fractures.

=================================

CBS NEWS Coverage of Breaking Space News

7:40 a.m. EST. 2/24/11/10 Update: Shuttle fueling begins; weather 90 percent 'go'

By William HARWOOD
CBS News Space Consultant

Hoping to put a three-and-a-half-month launch delay behind them, engineers began pumping a half-million gallons of liquid oxygen and hydrogen rocket fuel into the shuttle Discovery's external tank early Thursday to set the stage for blastoff on an 11-day space station resupply mission, the orbiter's 39th and final flight. Liftoff is targeted for 4:50:27 p.m. EST (GMT-5).

Forecasters are predicting a 90 percent chance of acceptable weather, with scattered clouds at 3,000 and 25,000 feet and winds at 14 knots with gusts to 20. The forecast calls for a 70 percent chance of good weather Friday as a cold front moves through the area, dropping to 60 percent "go" on Saturday. The launch window extends through March 6.

Working by remote control, engineers began the three-hour fueling procedure on time at 7:25 a.m., pumping liquid hydrogen and oxygen through transfer lines leading to the shuttle's aft engine compartment and from there, into the huge external tank.

If all goes well, the tank will be in "stable replenish mode" by around 10:25 a.m. At that point, attention will shift to the Johnson Space Center in Houston where flight controllers are monitoring an unmanned European cargo ship in the final stages of an automated approach to the International Space Station.

The Automated Transfer Vehicle 2, loaded with more than seven tons of supplies and equipment, was launched from Kourou, French Guiana, last week by an Ariane 5 rocket. Docking at the station's aft port is expected at 10:46 a.m. If there are any major problems, Discovery's launch could be delayed, but the craft has operated flawlessly since launch and flight controllers expect a trouble-free linkup.

Back at the Kennedy Space Center, commander Steven Lindsey, pilot Eric Boe, Nicole Stott, Michael Barratt and spacewalkers Stephen Bowen and Alvin Drew will begin strapping in around 1:30 p.m. to await liftoff on the 133rd shuttle mission.

"The launch team is not working any technical issues that would prevent us from launching on time this afternoon at 4:50 p.m. Eastern," said NASA commentator Allard Beutel.

The primary goals of Discovery's mission are to deliver a new cargo module loaded with supplies and equipment to the International Space Station along with an external storage platform and a spare set of cooling system radiators.

Launch originally was scheduled for Nov. 1, but the flight was delayed to Nov. 5 by technical problems, bad weather and then because of a leak in a gaseous hydrogen vent line attached to the side of the shuttle's external tank. When the tank was being drained in the wake of the launch scrub, engineers discovered cracks in the tank's foam insulation and launch was put on indefinite hold.

The gaseous hydrogen leak was blamed on subtle alignment issues with a quick-disconnect fitting that connects the vent line to the tank. Engineers were confident the vent line hardware, known as a ground umbilical carrier plate, or GUCP, would work normally this time around, but it typically takes an hour or more for the hydrogen tank to reach a level where a vent line leak might show up.

Fixing the quick-disconnect problem was relatively straight forward. But the foam cracks were symptoms of a more serious issue. When the damaged foam was cut away, engineers discovered fractures in underlying rib-like stringers used in the "intertank" compartment that separates the tank's liquid oxygen and hydrogen tanks.

The cracks occurred near the tops of several stringers where the vertical ribs meet a massive flange that supports the upper liquid oxygen tank.

An exhaustive engineering analysis blamed the cracks on the use of a more brittle than expected aluminum-lithium alloy, manufacturing issues and the effects of ultra low-temperature liquid oxygen at minus 423 degrees Fahrenheit. As the oxygen tank is loaded, the hardware contracts by several inches, pulling the tops of the stringers inward. They are designed for that, but the alloy used in Discovery's tank was more brittle than usual and cracks developed.

The fractures were repaired by splicing in fresh stringer sections, along with doublers to provide additional strength. To beef up the remaining stringers, so-called "radius block" doublers were riveted into place to make the ribs less susceptible to stress-relief fractures. In all, 105 of the 108 intertank stringers were modified. The goal was to ensure the tank's structural integrity and to prevent any cracks that could result in foam losses during ascent that could damage the shuttle's fragile heat shield.

Engineers were confident the modified tank is up to the rigors of fueling and launch. But just to be sure, cameras will be focused on the intertank during the remainder of the countdown and a final inspection team sent to the pad after fueling will be on the lookout for any foam cracks that might be indicative of underlying problems.

"The tank will get a 100 percent inspection and when the guys come back to the firing room and report out to us, the tank will be what it is," said Launch Director Michael Leinbach. "It's either going to be ready to go or there's going to be some issues. We don't expect any issues at all, but if there are, we're going to find them and we'll talk about them. ... I assure you, this tank will get a complete inspection, both in the firing room and by the final inspection team at the pad, before we commit her to flight."

Here is a timeline of the remaining countdown milestones (in EDT and launch-minus time; best viewed with fixed-width font):

EST...........EVENT

10:25 AM......Begin 2-hour 30-minute built-in hold (T-minus 3 hours)
10:25 AM......Closeout crew to white room
10:25 AM......External tank in stable replenish mode
10:28 AM......Ascent flight control team on console
10:40 AM......Astronaut support personnel comm checks
10:46 AM......ATV 2 docking with the International Space Station
11:10 AM......Pre-ingress switch reconfig
12:20 PM......Final crew weather briefing
12:30 PM......Crew suit up begins
12:55 PM......Resume countdown (T-minus 3 hours)

01:00 PM......Crew departs O&C building
01:30 PM......Crew ingress
02:20 PM......Astronaut comm checks
02:45 PM......Hatch closure
03:15 PM......White room closeout

03:35 PM......Begin 10-minute built-in hold (T-minus 20m)
03:45 PM......NASA test director countdown briefing
03:45 PM......Resume countdown (T-minus 20m)

03:46 PM......Backup flight computer load OPS 1 software
03:50 PM......KSC area clear to launch

03:56 PM......Begin final built-in hold (T-minus 9m)
04:21 PM......NTD launch status verification
04:41:27 PM...Resume countdown (T-minus 9m)

04:42:57 PM...Orbiter access arm retraction
04:45:27 PM...Launch window opens
04:45:27 PM...Hydraulic power system (APU) start
04:45:32 PM...Terminate LO2 replenish
04:46:27 PM...Purge sequence 4 hydraulic test
04:46:27 PM...Inertial measurement units to inertial
04:46:32 PM...Aerosurface test profile
04:46:57 PM...Main engine steering test
04:47:32 PM...LO2 tank pressurization
04:47:52 PM...Fuel cells to internal reactants
04:47:57 PM...Clear caution-and-warning memory
04:48:27 PM...Crew closes visors
04:48:30 PM...LH2 tank pressurization
04:49:37 PM...Booster joint heater deactivation
04:49:56 PM...Shuttle flight computers take control of countdown
04:50:06 PM...Booster steering test
04:50:20 PM...Main engine start (T-6.6 seconds)
04:50:27 PM...Booster ignition (LAUNCH)

=================================

CBS NEWS Coverage of Breaking Space News

2 PM, 02/22/11/10 Update: NASA managers 'go' for shuttle Discovery's final launch

By William HARWOOD
CBS News Space Consultant

With good weather expected, NASA managers Wednesday cleared the shuttle Discovery for launch Thursday on a long-delayed space station resupply mission, the orbiter's 39th and final flight.

Mike Moses, the shuttle integration manager at the Kennedy Space Center, said Discovery's countdown was proceeding smoothly with no technical problems of any significance at pad 39A.

"Today we held our launch minus-one-day mission management team meeting where we got together just to discuss our current status and our readiness," he told reporters. "Everything is on track, going beautifully with the countdown and we are more than ready for tomorrow's launch."

Discovery is scheduled for liftoff at 4:50:27 p.m. EST (GMT-5), the middle of a 10-minute window that roughly coincides with the moment Earth's rotation carries the launch pad into the plane of the International Space Station's orbit. The shuttle must launch within five minutes of that "in-plane" time to reach the lab complex.

Shuttle weather officer Kathy WInters said forecasters are continuing to predict an 80 percent chance of good weather. The outlook deteriorates slightly over the next few days as a frontal system moves through the area, with the odds dropping to 70 percent "go" Friday and 60 percent on Saturday.

The primary goals of the 133rd shuttle flight are to deliver supplies, science gear, spare parts and other equipment to the space station, along with a final U.S. module that will be used as an orbital storage depot.

"We've been ready from a mission standpoint for quite a while, now our hardware's in line and ready to go," Moses said. "We're delivering the PMM, the permanent Multi-purpose Module, which will be basically a really good addition to space station in terms of storage capability on orbit.

"We're taking up the ELC-4, external logistics cargo pallet, which has a spare radiator and room for other spare hardware once it gets on orbit and stowed on the station. We have two very busy EVAs (spacewalks) to clean up a lot of (unfinished) activities and prepare the station for the future."

The astronauts also will deliver science hardware and a variety of experiments, along with a humanoid technology demonstration robot known as Robonaut 2.

"So we're really looking forward to a very action-packed, successful mission and everything's on track," Moses said.

Launch originally was planned for last Nov. 1, but the flight was delayed by technical problems, bad weather and ultimately by cracks in the ship's external tank. The cracks have since been repaired and structural stiffeners were added to make rib-like stringers less susceptible to stress-relief fractures.

Launch Director MIke Leinbach said figuring out the root cause of the cracks was one of the most challenging realtime shuttle problems in the 30-year history of the program. But "we fixed the tank, we're going to fly it tomorrow and it's going to perform perfectly fine."

Discovery is NASA's most seasoned orbiter and it will be making its final voyage Thursday, followed by the final flight of Endeavour in April and Atlantis later this summer.

Asked if emotions were running high going into Discovery's final launch count, Leinbach said "the last flight of all three vehicles is going to be emotional for all of us."

"Landing day's going to be tough," he said. "Landing day of Discovery, and then Endeavour and especially Atlantis, the last mission, you'll see a lot of people on the runway who will probably choke up some. Because it's the end of a 30-year program that not only have we worked in and made our livelihoods in, but we've grown to love and appreciate and feel like we're doing something special for the country and, really, the world. And it's coming to an end, and that's tough.

"But we're going to do it right, we're going to approach each of these three flights the way we approached all the other ones, we'll pull them off and be able to look back and be very, very proud of what we've accomplished in the shuttle program."

=================================

CBS NEWS Coverage of Breaking Space News

12:35 PM, 02/22/11/10 Update: Shuttle countdown on track for Thursday launch

By William HARWOOD
CBS News Space Consultant

The shuttle Discovery's countdown is ticking smoothly toward launch Thursday on a space station re-supply mission. There are no technical problems of any significance at pad 39A and forecasters are continuing to predict an 80 percent chance of good weather.

"At the moment, everything's going well with the countdown, we all take immense pride in the work and the accomplishments of the team and of this vehicle, and we're all looking forward to a successful launch on Thursday," NASA Test Director Steve Payne told reporters Tuesday.

Shuttle weather officer Kathy Winters repeated the forecast she gave Monday, saying the odds are 80 percent "go" Thursday, dropping to 70 percent and 60 percent Friday and Saturday as a front moves through the area.

Working by remote control, engineers worked Tuesday to pump liquid oxygen and hydrogen aboard the shuttle to power the ship's three electricity producing fuel cells. After loading, the team planned to drain 120 pounds of liquid oxygen to fine tune the orbiter's weight and improve its "ascent performance margin."

Main engine preparations will begin early Wednesday, followed by avionics system checkouts and activation of the shuttle's communications systems. A protective gantry will be rotated away from the shuttle at 8 p.m. Wednesday, exposing Discovery to view and clearing the way for fueling.

The three-hour fuel loading procedure is scheduled to begin at 7:25 a.m. Thursday. Shortly after the tank is topped off with more than 500,000 gallons of liquid oxygen and hydrogen rocket fuel, the European Space Agency's Automated Transfer Vehicle 2, an unmanned cargo ship, is scheduled to complete a computer-controlled docking at the International Space Station's aft port.

The ATV-2, also known as Johannes Kepler, was launched Feb. 16 by an Ariane 5 rocket from Kourou, French Guiana. It is carrying more than 7 tons of supplies and equipment and any major problems getting the craft docked at the station could impact Discovery's launch.

But the cargo ship is operating flawlessly and NASA managers do not expect any problems.

Back on Earth, engineers plan to pay special attention to Discovery's external tank after it is loaded with super-cold propellants, on the lookout for any cracks in the tank's foam insulation that might indicate an underlying fracturet.

Discovery was grounded in the wake of a Nov. 5 launch scrub because of small cracks near the tops of several rib-like "stringers" in the central intertank section where they meet a massive flange that supports the upper liquid oxygen tank. Testing and analysis showed the cracks most likely were the result of temperature-induced stress on stringers made with an aluminum-lithium alloy that was more brittle than usual.

The existing cracks were repaired and the top few inches of most of the 108 stringers used in the intertank were beefed up with so-called "radius blocks" that were riveted into place on top of the stringer attachment "feet" to make them less susceptible to fractures.

Engineers do not expect any additional problems, but an inspection team sent to the pad after fueling to look for signs of ice or anything else that could cause a problem during ascent will be on the lookout for foam cracks, photographing the stringer/flange area for detailed analysis before final clearance to launch.

Discovery is scheduled for liftoff at 4:50:24 p.m. EST (GMT-5) Thursday. With just three shuttle flights left on NASA's manifest before the fleet is retired this summer, Payne said he expects a big turnout.

"It's generated a lot of interest," he said. "The last few missions, people are starting to realize they either see one now or they don't get to see one at all. We've had some pretty good crowds come the last couple of times, we expect an equally large crowd (Thursday).

"It ought to be a good show. It's a good time of day, it's an excellent vehicle and it's always impressive to watch. So I'm sure we'll have a full house."

=================================

CBS NEWS Coverage of Breaking Space News

07:45 AM, 02/22/11/10 Update: STS-133 mission preview (updated)

By William HARWOOD
CBS News Space Consultant

Three-and-a-half months after the shuttle Discovery was grounded by potentially dangerous cracks in its external tank, the orbiter is finally back on track for launch Feb. 24 to deliver critical spare parts, supplies and a final U.S. module to the International Space Station.

During an executive-level flight readiness review Feb. 18, senior NASA managers cleared Discovery for blastoff Feb. 24, at 4:50:24 p.m. EST (GMT-5), following an exhaustive safety analysis of the modifications used to beef up suspect ribs, or stringers, in the tank's central "intertank" section.

"This is probably one of the most difficult technical issues, I think, we've ever faced because the answers were not obvious," shuttle commander Steven Lindsey said in a NASA interview. "It wasn't obvious what was wrong, why it was wrong, or how to fix it, and then you had the additional, if you will, pressure of the shuttle program winding up and we keep slipping and slipping and slipping.

"But to the space shuttle program's credit, they've really done due diligence on this one and really focused on the engineering, following the data, figuring out what was wrong. ... It's just been very impressive to watch them, not get rushed, focus on the data, focus on the engineering. When they didn't understand something, they did a lot of testing.

"You can write a thousand computer programs, but one test makes all the difference because that tells you what's really going on," he said. "So I think they've done a great job with it."

Lindsey and his five crewmates -- pilot Eric Boe, Nicole Stott, Michael Barratt and spacewalkers Stephen Bowen and Alvin Drew -- flew to the Kennedy Space Center Sunday to prepare for the start of the shuttle's countdown at 3 p.m. Monday.

A veteran of two previous shuttle flights, Bowen joined Discovery's crew in January after Timothy Kopra, the mission's original flight engineer and lead spacewalker, suffered what sources said was a broken hip in a bicycle accident near his home in Houston.

"It was actually a sad story," Bowen said in a NASA interview. "Tim had worked for well over a year putting this thing together and had an accident. He's unable to make the launch time frame (and) we needed to find somebody to fill his role. ... It was not what you expected, not what you want. Tim worked really hard."

Bowen, a veteran submariner with five previous spacewalks to his credit, was a natural choice to replace Kopra on short notice. He flew aboard the most recent shuttle mission and served as the lead astronaut in the spacewalk office at the Johnson Space Center.

He underwent accelerated training for the two spacewalks planned for Discovery's mission, joining Drew for four simulation runs in NASA's huge neutral buoyancy training pool near the Johnson Space Center.

Because of time constraints, Bowen did not attempt to assume Kopra's duties as flight engineer. Instead, Drew will take on that role for launch and Stott will serve as flight engineer for Discovery's re-entry and landing.

"I get to concentrate on just the EVA portion," Bowen said. "Tim and Drew had put together a great plan. I literally told the EVA team don't change a single word of the plan, I'm going to follow what he wrote. I've been watching the videos of what Tim did in the (training tank) and I’ve been talking to Tim as well and learning how to do these EVAs."

Kopra plans to help out in mission control during the flight, providing advice as needed based on his own experience training.

The primary goals of the 133rd shuttle mission are to deliver critical spare parts, supplies and a final U.S. module to the International Space Station. It will be Discovery's 39th and final flight as NASA presses ahead with plans to retire the fleet after just three more missions.

"Discovery's a workhorse, the fleet leader in number of flights, done a lot of famous flights, all the return-to-flight test missions," Lindsey said before the crew's initial launch attempt. "Yet when you walk inside Discovery, it still looks like a new car even after almost 30 years of service. It's a great machine, a great vehicle. It's a privilege for us to be able to fly it on the last flight."

Assuming an on-time launch, Lindsey and Boe will oversee a two-day rendezvous with the lab complex, carrying out a now-routine heat-shield inspection the day after liftoff before guiding the shuttle to a docking at the station's forward port around 2:16 p.m. on Feb. 26. It will be Discovery's 13th and final docking.

Waiting to welcome the shuttle astronauts aboard will be Expedition 26 commander Scott Kelly, Alexander Kaleri, Oleg Skripochka, Catherine Coleman, Dmitry Kondratyev and Italian astronaut Paolo Nespoli.

Discovery is scheduled to spend seven days docked to the space station, departing on March 5 and landing back at the Kennedy Space Center around 12:44 p.m. on March 7.

But U.S. and Russian space managers are expected to approve a one-day mission extension for an out-of-this-world photo opportunity.

The idea is to insert a new flight day 10 in the crew's timeline -- March 5 -- so Kelly, Kaleri and Skripochka can undock in the Soyuz TMA-01M spacecraft and photograph the space station with the shuttle and a full complement of European, Japanese and Russian cargo ships and crew capsules attached.

Discovery's mission is the last time all of the international spacecraft will be docked at the station at the same time before the shuttle fleet is retired later this summer.

Assuming the fly-around is approved -- and no decisions are expected until after Discovery reaches the space station -- Discovery would undock on March 6 and land in Florida around 11:35 a.m. on March 8.

A LONG ROAD TO LAUNCH

NASA originally hoped to launch Discovery on Nov. 1, but the flight was delayed to Nov. 5 by bad weather and technical problems.

The ship was fueled for launch Nov. 5, but the countdown was called off when sensors detected a gaseous hydrogen leak in a quick-disconnect fitting used to attach a vent line to the side of the tank. That problem was quickly resolved, but engineers also discovered cracks near the tops of two adjacent structural rib-like "stringers" near a flange in the external tank that supports the upper liquid oxygen tank. More cracks were found later, after Discovery was returned to NASA's Vehicle Assembly Building for more detailed inspections.

Tracing the manufacturing history of the tank, engineers discovered that most of the original 108 stringers in the "intertank" section that separates the tank's oxygen and hydrogen sections were made using an aluminum-lithium alloy from a lot that was more brittle than usual and more susceptible to temperature-induced fractures when the tank is loaded with super-cold propellants.

That weakness, engineers concluded, along with subtle manufacturing issues, were the most likely causes of the observed cracks.

In the most invasive repair of an external tank ever attempted, engineers installed structural stiffeners, called radius blocks, to better secure the top few inches of 105 stringers to prevent cracks from forming when the tips of the stringers are pulled inward due to the contraction of the liquid oxygen tank.

The goal was twofold: to ensure the tank's overall structural integrity and to prevent cracks that could cause foam insulation to pop off during the climb out of the dense lower atmosphere when debris impacts pose the greatest threat to Discovery's fragile heat shied.

The addition of the radius blocks more evenly distributes stresses in the stringers and reduces the strains on the top few fasteners.

The tank was designed to be structurally "fail safe" even if three adjacent stringers developed cracks. Data from a Dec. 18 fueling test, elaborate laboratory tests and an exhaustive engineering analysis showed the tank would remain structurally sound even if more than three stringers developed cracks greater than four inches in length as long as they were separated by undamaged stringers.

The tank's calculated factor of safety is not precisely known, but it is greater than one in all cases, meaning that even with extensive modifications and stringers that are more brittle than usual, the structure's strength is sufficient for flight.

Testing also showed cracks greater than four inches long were most likely to occur during fueling, when the hardware is "shocked" by extreme low temperatures and that any such fractures likely would cause visible cracks in the tank's insulation. With the radius block modifications, engineers do not expect such cracks to form. But during Discovery's countdown, cameras will be focused on the liquid oxygen flange area to look for any signs of insulation damage. If any cracks are seen, the countdown will be called off.

Bill Gerstenmaier, director of space operations at NASA headquarters, praised the NASA and contractor engineers and technicians who did the troubleshooting, analysis and repairs of Discovery's tank. Many members of the repair team were called in from Lockheed Martin's Michoud Assembly Facility near New Orleans where the giant tank was built. With only three more shuttle flights planned, the production line has been shut down.

"They did a phenomenal job of doing this testing and pulling the work together," Gerstenmaier said. "I couldn't be prouder of what they've done. ... A lot of these folks, some of them in the tank world, were laid off, they were already in other jobs and we called them back to do some of this work. ... There was no question about their dedication. They really want to see this vehicle fly."

HISTORIC MILESTONES AND CHALLENGES FOR NASA

Discovery's delayed launching comes at a historic moment for NASA and its international partners. On April 12, NASA will mark the 30th anniversary of the first shuttle flight and the Russian space program will celebrate the 50th anniversary of Yuri Gagarin's launch on the first manned space flight.

Discovery's docking with the International Space Station will come just over 12 years after the Nov. 20, 1998, launch of the station's first component, the Russian Zarya module, and 10 years after the first three-man crew arrived aboard a Russian Soyuz spacecraft Nov. 2, 2000.

Since then, the space station has grown to include 13 pressurized modules and a huge solar array power truss stretching the length of a football field and tipping the scales at nearly 900,000 pounds. The lab has been continuously manned by rotating two-, three- and now six-person crews.

"I delivered the airlock on my first flight to space station," Lindsey said in a NASA interview. "It had just barely started and I remember thinking about all of the missions and all the components we still had to fly up there to fully build this thing out. At times it seemed like we were never going to get there. It was just, there were so many missions.

"When I look back at it now and see this fully assembled space station operating with six people and doing all the science and stuff like that, I'm just amazed at what this big team has accomplished and really excited about what it's going to accomplish in the future.

"Getting an opportunity to go up there again, which I never thought was going to happen, and see this fully assembled space station I've worked on most of my professional career here at NASA is just going to be something fantastic. I hope that the rest of the world appreciates what we have."

When Lindsey and his crewmates were named to the crew of shuttle mission STS-133, NASA intended Discovery's flight to be the program's final voyage, following a Bush administration mandate to finish the space station and retire the shuttle fleet by the end of fiscal year 2010.

That somewhat arbitrary deadline was relaxed a bit when Congress, worried about the possibility of schedule pressure on flight safety, promised an additional $600 million in funding to cover shuttle operations through the end of the calendar year. NASA managers later said internal cost-savings initiatives would allow shuttle operations to continue into early 2011 if necessary.

As it turned out, problems with a $2 billion particle physics experiment scheduled for launch aboard the shuttle Endeavour during the next-to-last fight in July 2010 forced NASA to revise the end-of-program shuttle manifest.

Because of work to replace the powerful magnet in the particle physics experiment, Endeavour's flight leap-frogged Discovery's, slipping to late November and eventually to Feb. 27, 2011. Discovery's flight, in turn, slipped from mid September to Nov. 1, in part to accommodate work to modify a cargo transport module for permanent attachment to the space station.

Discovery's launching then was delayed to Nov. 5 by bad weather and technical snags. The ship has been grounded since then because of the stringer cracks.

In the midst of Discovery's long launch campaign, NASA won political support for a third and final mission with the shuttle Atlantis to deliver additional supplies and equipment to the station. That flight, the shuttle program's final voyage, is targeted for launch June 28.

After the shuttle fleet is retired, NASA will rely on smaller unmanned Russian, European and Japanese cargo ships, along with new commercial spacecraft that are currently in development, to deliver the supplies and equipment needed by the space station to support a full-time crew of six.

"From a logistics standpoint, 2012 is going to be a real challenge for (the station program)," said shuttle Program John Shannon. "If there are delays in any of the new vehicles that are expected to deliver cargo to the station, that problem is just going to be exacerbated. It's hard to compare vehicles and capabilities. But my operations guy said one shuttle flight is roughly equivalent to about seven (Russian) Progress flights. So if you think about that, you can do pretty well on one shuttle.

"So getting to fly (Atlantis) late is going to give the space station margin from a logistics standpoint to keep six crew (members) up, to keep doing the research, to keep doing the utilization even if some of those new vehicles are delayed by some period of time."

If the Atlantis mission is not launched "and the new vehicles that are going to deliver cargo are delayed, and we end up having a logistics shortfall in 2012, and we have to go down to three crew, and we're not doing research, we have made a major error, in my opinion," Shannon said.

Faced with an uncertain budget, Shannon is struggling to reduce the shuttle workforce as required while maintaining flight safety and maximizing resupply of the space station.

Despite extensive layoffs, "the program is very healthy," Shannon said. "But I have a very high sense of paranoia that this is a very difficult time for the team, and we need to be incredibly vigilant, and any little noises that you hear you've got to go pay attention to and really make sure you fully understand what is going on. Because it's a very complex process and it's very unforgiving.

"So far, the team has done an outstanding job and we're going to continue to stay focused. The team really wants to preserve the legacy of the shuttle program and end on a really high note."

A FINAL U.S. MODULE FOR THE SPACE STATION

As originally planned, Discovery's flight did not include any spacewalks. But with the schedule revision and the initial slip to November, NASA managers added two spacewalks, or EVAs, with Drew and Kopra -- now Bowen -- and scheduled additional work to maximize the resupply effort.

"We started out as an eight-day mission," Lindsey said. "We were just going to go up, dock with space station, offload some payloads and (do) a lot of transfer and basically leave station in the best logistic state possible because when we were originally assigned we were going to be the very last shuttle mission.

"They've added a couple of spacewalks to our flight so what we've had to do is lengthen the mission from eight days to eleven days nominal with a plus one if we need it. We're having to pick up and train (for) those two spacewalks, which we hadn't been training for before. We've also added a whole bunch of robotics that go along with that.

"As a result of that, I've had to move crew members into different tasks to make the timeline fit. ... We have a good schedule in place, and we've worked out all those details. It's just going to take us a little bit longer to get there, but we still have a good plan and I feel pretty comfortable with what we're doing."

At the heart of the mission is the permanent multi-purpose module, or PMM, that will be carried aloft in Discovery's cargo bay. The Italian-built module, dubbed Leonardo, was originally designed to serve as an up-and-down cargo transport canister that could be temporarily docked to the space station and then returned to Earth aboard the shuttle.

Then called a multi-purpose logistics module, or MPLM, Leonardo was not designed to remain permanently attached to the station. But with shuttle flights coming to a close, program managers ordered modifications, beefing up Leonardo's insulation, adding increased orbital debris shielding and arranging for power, lights and ventilation. The result is the PMM.

"I think it's going to be a really outstanding addition to the station," said Stott. "Anybody who's lived and worked up there has at one time or another felt like wow, if we just had a closet where we could stick this, or we just had designated storage for these particular items it would be such a great thing.

"And I think what it's going to do is provide that, but it's also going to give us the opportunity to go through station and look at where we have stuff and maybe better distribute so we make even more space available. So I think it's going to be a really, really nice addition."

Mounted in Discovery's cargo bay, the PMM measures 21 feet long and 15 feet in diameter and tips the scales at 21,817 pounds, including 6,536 pounds of equipment and supplies. Another 1,568 pounds of station-bound gear is mounted in the shuttle's crew cabin.

The station-bound hardware includes an experiment rack, a heat exchanger for the lab's temperature and humidity control system, a spare pump for the station's internal cooling system, a large fan, a water processing assembly storage tank, a waste water tank and an experimental robot known as Robonaut 2.

Shaped like a human's upper torso, Robonaut 2 weighs about 300 pounds and measures nearly four feet from waist to head and nearly three feet across the shoulders. The robot will be operated remotely by engineers on the ground.

Describing the robot as a technology demonstrator, Barratt said "this is very much a first step. We'll be identifying some breadboard tasks over the next few years to figure out how best to use a humanoid robot in space."

"When you look at some of the tasks we're asked to do, and what a robot could do, you're thinking of things that would be perhaps dangerous for a human to do or repetitive tasks that would wear a human out," he said. "So if you were to go around the station, for instance, and identify scenarios where it was risky to send a human in, whether you had a suspected fire or a toxic release and what you needed was a switch throw or to discharge a fire extinguisher into the right fire port, that's the kind of thing we could eventually envision sending Robonaut in to do.

"I'd much rather send a robot in than go in myself on a gas mask," he said. "But again, we're very early, and we'll be mapping those tasks to the capabilities that Robonaut demonstrates over the years. And it will be years before we figure all this out. So we're excited to see this all start."

Discovery also is carrying up an 8,161-pound external storage platform carrying a folded set of radiators that will serve as a spare in case of future problems with the station's external cooling system. The station features two independent coolant loops that circulate ammonia through huge radiators to dissipate the heat generated by the lab's electronics.

The spare radiator panels weigh 2,475 pounds and are mounted on an external logistics carrier known as ELC-4. Barratt and Stott, operating the station's robot arm, will lift ELC-4 out of Discovery's cargo bay a few hours after docking on flight day three. They will hand it off to Boe, operating the shuttle's robot arm, and then reposition the station arm. After re-grappling the cargo carrier, Barratt and Stott will mount it on the right side of the station's power truss.

The next day, Barratt and Stott will use the station arm to pull the shuttle's heat shield inspection boom out of the cargo bay before handing it off to Boe and the shuttle's arm where it will remain for possible use later in the mission. Inside the station, the astronauts will begin work to repair one of the U.S. segment's carbon dioxide removal systems.

Bowen and Drew will end the day by camping out in the station's Quest airlock module at a reduced pressure of 10.2 pounds per square inch. The camp out procedure is used to help purge nitrogen from the bloodstream before spacewalks are conducted in NASA's 5-psi spacesuits.

The first major objective of the mission's first spacewalk on flight day five is to install a 10-foot-long power cord between the Quest airlock and the Harmony module directly across the station on the other side of the Unity module. The power line, which might be needed in the future if Harmony ever needs to be undocked for repairs, cannot be installed after the PMM is attached to Unity's Earth-facing port.

With the power line in place, Bowen and Drew will retrieve a failed ammonia pump module that was left temporarily stowed on the robot arm's mobile base system after a three-spacewalk repair job last August. After moving the module back to a stowage platform, Drew will install a vent line that will be used during the crew's second spacewalk to dump about 10 pounds of residual ammonia overboard.

Most of the remaining tasks were left over from earlier missions.

"On my last flight and on the next flight, there's not a lot of time to do all the tasks that have just built up over the past year," Bowen said. "Originally when this flight was assigned, there were no EVAs on it but they wisely saw they had the talent with Tim and Al and Mike and Nicole to put a good team outside and use that talent to get some work done.

"These were two EVAs that were not originally in the plan, that they've taken advantage of the fact that they have these guys on board. They're going around, and we will be doing a lot of items, a lot of stuff. It’s going to be busy."

With the pump module safely stowed, Drew and Bowen plan to carry out a variety of maintenance tasks, adjusting the insulation on the upper Z1 truss, attaching a tool stanchion and a wedge to tilt a camera away from ELC-4, providing additional clearance when hardware arrives aboard future supply ships.

Before ending the spacewalk, Bowen and Drew will open a Japanese container and "fill" it with the vacuum of space in a project known as "message in a bottle."

"It's a Japanese piece of hardware and the intention here is to use this outside space station and all we want to do is open a valve," Kopra said before the crew's initial launch attempt. "It's kind of unique and a thoughtful sort of experiment the Japanese have designed where we're just going to fill it with the vacuum of space. ... Clearly a vacuum is a vacuum whether it's space or if it's in a vacuum chamber here at NASA. But this is a little bit special, especially for the Japanese because it's the vacuum of space. So we'll do that, capture in pictures and provide that to the Japanese once we come home."

The next day, flight day six, Stott and Barratt, operating the station's robot arm from inside the multi-window cupola, plan to pull the PMM out of Discovery's payload bay and attach it to Unity's Earth-facing port. That afternoon, a block of time is set aside for a so-called "focused" inspection of the shuttle's heat shield if any problems are spotted after launch or during approach to the station.

That night, Bowen and Drew will camp out in Quest to prepare for another spacewalk the next morning.

The goals of the second excursion are to vent residual ammonia from the failed pump module, to retrieve a European experiment package from the outboard end of the Columbus laboratory module, to install protective lens covers on external cameras that could be "plumed" by approaching cargo ships and to troubleshoot problems with mounting hardware that could be needed in the future for radiator repairs or replacement.

Inside the station, the astronauts will complete outfitting the vestibule between Unity and the PMM, opening the hatch and floating inside for the first time. Unlike normal MPLM missions, the crew will be in no hurry to unload the supplies and equipment ferried aloft in the PMM. Robonaut 2, for example, is not expected to be activated for several months.

Over the next two days, the astronauts will enjoy a bit of off-duty time, participate in multiple interviews and a traditional joint crew news conference. What happens after that depends on whether the Soyuz fly-around is approved.

The pre-launch flight plan called for Discovery to undock from the station around 7:37 a.m. on March 5. After looping around the outpost for a photo-documentation inspection, the shuttle crew would depart and pull away before carrying out a final heat shield inspection to look for any signs of damage since the initial inspection the day after launch.

Discovery's 39th and final landing would be targeted for around 12:36 p.m. on March 7.

If the Soyuz fly-around is approved, however, undocking and landing would be delayed one day and a new flight-day 10 would be inserted into the timeline for March 5.

DISCOVERY WRAPS UP A DISTINGUISHED CAREER

"I don't think you can take a final voyage of a ship of exploration and not take some moments to celebrate its history," Barratt said. "As many people know, our ship Discovery, which is a ship of exploration, was named after several predecessor ships, all named Discovery, all ships of exploration.

"It's the culmination of a great heritage, really, and we hope there are future ships bearing that name. We will be carrying a medallion from the Royal Society that was struck in honor of Captain Cook. On Cook's third voyage, there was a ship called Discovery and that's the main ship for which our ship took its name. We'll be doing a few other taped commemoratives on it as well. But again, you cannot not celebrate the history and the heritage of this ship."

The contract authorizing construction of Discovery was awarded Jan. 29, 1979, and initial work to begin building the crew module began the following August. The spacecraft was completed at North American Rockwell's Palmdale, Calif., plant in October 1983 and was ferried to the Kennedy Space Center Nov. 9, 1983.

Following an on-pad main engine test firing June 2, 1984, NASA attempted to launch Discovery on its maiden voyage the following June 26. But in a moment of high drama, the shuttle's main engines shut down seconds after ignition because of a sluggish fuel valve.

The problem was corrected, and commander Henry Hartsfield and his crew, including Challenger astronaut Judith Resnik, finally blasted off Aug. 30, 1984, on a successful mission to deploy three commercial communications satellites and to test space station construction techniques.

Over the next 26 years and 38 flights, Discovery carried out four military missions, two Spacelab science flights, two visits to the Russian Mir space station, one Mir docking and 12 missions to the International Space Station. At least 24 civilian and military satellites were carried into space, including the Hubble Space Telescope.

During Discovery's final mission, the ship will make its 13th docking with the space station, and its crew will carry out the orbiter's 50th and 51st spacewalks.

Veteran of two on-pad launch aborts, Discovery also flew the return-to-flight missions following the 1986 destruction of the shuttle Challenger and the 2003 loss of Columbia. In addition, two stranded communications satellites were plucked out of orbit by spacewalking astronauts and brought back to Earth for repairs in November 1984 in what many veterans consider the most daring shuttle mission ever attempted.

Going into its final flight, Discovery had logged 142,917,535 miles traveled over 5,540 orbits, carrying 246 astronauts and cosmonauts into space, including former senator and Mercury astronaut John Glenn and Eileen Collins, the first woman to pilot and later command a space shuttle.

"When you really look at the space shuttle and its capability, it can do everything, everything you can think of in space except for one thing, it can't leave low-Earth orbit, but it can do everything else," Lindsey said in a NASA interview. "It can do robotics. It can do science. It can go dock. When you dock with the space station, in the end you have to maintain a three-inch corridor and one degree of attitude error and you can easily fly the shuttle manually and maintain that. I mean, that's unbelievable for a 120-ton vehicle.

"I don't think there's going to be another one that's ever going to match the versatility of the space shuttle, and I think that's the legacy. All the systems we've developed and things we've done on space station, or on space shuttle, have all had impacts in our society. I mean, literally any room you walk in, anything you do during the day, you can point at things in that room and say, 'That came out of the space program. This came from shuttle. This came from Apollo. This came from space station' and you can see it all around you.

"The public's not real aware of all of that ... and it's very hard to measure, but it's all there if you really think about it, and I think that's the legacy. I think the legacy is that all these things came out of it, and people take all of those things for granted."

NASA managers are considering a variety of options for Discovery's post-landing processing. Some have suggested maintaining the orbiter in a flight-ready state for as long as possible. Others have recommended using the orbiter for spare parts until Atlantis and Endeavour complete their final missions. Shannon favors a combination of approaches.

"We're in the middle of a very significant effort to identify hardware off of Discovery and also in the spares (inventory) that could be used for some future as yet unknown program, or that we would want to maintain as spares for Endeavour and Atlantis," Shannon said.

"We're also going to pull some off as engineering teaching units so that future generations will be able to take the hardware that was flown on the shuttle and dissect it and understand the engineering and how it was put together. We're also going to go in and look at some hardware on Discovery that has flown for 30 years that we've never looked at before. Things like actuators and some structural areas that are impossible to get to.

"Those will be fairly invasive, it will take time and it will take money," he said. "But I think that's one of the legacies the shuttle can provide. ... So even after Discovery lands, we will not be finished learning about the space environment. That's my goal, to start immediately on that."

No matter how the end game plays out, Discovery eventually will be shipped to a museum and put on display. But with nearly two dozen museums vying for one of NASA's three orbiters, it's not yet clear where Discovery will end up. A decision is expected later this year.

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CBS NEWS Coverage of Breaking Space News

3:30 p.m. EST. 2/21/11/10 Update: Countdown begins for Thursday shuttle launch

By William HARWOOD
CBS News Space Consultant

Engineers restarted the repaired shuttle Discovery's countdown Monday, setting the stage for launch Thursday on a space station resupply mission that's been grounded since November because of cracks in the ship's external tank.

The countdown began at 3 p.m. EST (GMT-5) and if all goes well, Discovery will blast off on its 39th and final flight at 4:50:24 p.m. Thursday, roughly the moment Earth's rotation carries the launch pad into the plane of the International Space Station's orbit.

"The people who work on this team have loved Discovery for many, many years," said NASA Test Director Jeffrey Spaulding. "And so it's a bittersweet thing for them to say goodbye to her. ... I think everybody's proud of what they've done and they're really happy to see her go off on this last mission."

Spaulding said there were no major technical problems going into the countdown and weather officer Kathy Winters said forecasters expect an 80 percent chance of acceptable conditions Thursday. Higher-than-allowable winds are expected at NASA's backup emergency landing sites in California and New Mexico, but with good weather expected in Florida and at two emergency runways in Europe, there are no constraints to launch.

The forecast deteriorates somewhat after Thursday, however, dropping to 70 percent "go" on Friday and 60 percent Saturday. After that, NASA managers will have to work around two upcoming unmanned launches that use the same Air Force tracking systems as the shuttle. Discovery's launch window closes March 6 to avoid conflicts with an upcoming Russian Soyuz mission.

NASA originally hoped to launch Discovery in November, but the flight was delayed by technical problems, bad weather and, ultimately, by cracks in structural rib-like "stringers" in the shuttle's external tank. The cracks have been repaired and the tank was modified to prevent the formation of any additional stress-related cracks.

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CBS NEWS Coverage of Breaking Space News

05:45 p.m. EST. 2/2/11/10 Update: Discovery crew flies to Florida to prep for Thursday launch

By William HARWOOD
CBS News Space Consultant

The shuttle Discovery's five-man one-woman crew flew to the Kennedy Space Center Sunday to prepare for another launch try Thursday, more than three-and-a-half months after the flight was put on hold because of cracks in the ship's external tank.

"It's great to be back at the Cape," said commander Steven Lindsey. "We're back here for another attempt at this. We're pretty confident about this one."

Lindsey and his crewmates -- pilot Eric Boe, Nicole Stott, Michael Barratt and spacewalkers Stephen Bowen and Alvin Drew -- originally hoped to launch last year, but the mission was grounded in the wake of a Nov. 5 launch scrub when stress-relief cracks were discovered in rib-like "stringers" used in the ship's external tank.

The tank has since been modified to make it less susceptible to temperature-induced cracks and senior managers, attending a flight readiness review Friday, unanimously cleared Discovery for launch.

"I'd like to thank the team, the shuttle team in particular, all the folks here and working at all the centers across the country," Lindsey said at the shuttle runway. "The external tank problem we've been working the last several months is probably one of the most difficult technical challenges we've faced in recent years. But the team did a great job coming together, figuring out a very difficult engineering problem, coming up with a solution that I think gives us a really good tank to go launch with this week."

Lindsey also thanked astronaut Timothy Kopra, the mission's original flight engineer and lead spacewalker, who was replaced by Bowen after being injured in a bicycle accident last month near his home in Houston.

"We had a real challenging training flow to try to bring Steve Bowen in and get him up to speed to take Tim's place," Lindsey said. "Right now, I'd like to thank Tim for all that he's done for us. We're all disappointed he's not going to be here. If it wasn't for Tim developing our EVAs as the lead spacewalker ... we couldn't have pulled this off in four weeks of training and be ready to go.

"But I'm happy to say our training's complete and we're ready to go. Steve Bowen has jumped into the crew and just done a fantastic job. ... So we're ready to fly. We're anxious for hopefully good weather and a good vehicle and launch and go up to the space station."

Shuttle engineers plan to start Discovery's countdown at 3 p.m. EST (GMT-5) Monday. "If all goes well, Discovery will blast off on its 39th and final mission at 4:50:24 p.m. Thursday. Docking at the International Space Station is expected around 2:16 p.m. Saturday.

"It's always a great thing to come back to KSC," said Barratt. "Last night, we were able to watch the station pass over Houston. The conditions were perfect and it was just incredibly bright. It's amazing to think we put that up there, piece by piece, a lot of it from this very place and that we'll be chasing it down by the end of the week. We're really, really looking forward to that."

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CBS NEWS Coverage of Breaking Space News

08:00 PM, 2/18/11/10 Update: NASA clears shuttle Discovery for Feb. 24 launch

By William HARWOOD
CBS News Space Consultant

NASA managers Friday cleared the shuttle Discovery for launch next Thursday on a long-delayed space station resupply mission after an exhaustive review of ground processing and unprecedented external tank repairs to fix and prevent potentially dangerous cracks in the ship's external tank like those that derailed a launch try last November.

Discovery's six-member crew -- commander Steven Lindsey, pilot Eric Boe, Nicole Stott, Michael Barratt and spacewalkers Stephen Bowen and Alvin Drew -- plans to fly to the Kennedy Space Center Sunday afternoon for the start of the ship's countdown at 3 p.m. EST (GMT-5) Monday.

If all goes well, Discovery will blast off on its 39th and final mission at 4:50:24 p.m. Thursday, more than three-and-a-half months after the ship was grounded to resolve the external tank crack problem.

Along with fixing the tank, NASA also had to revise the mission flight plan to reflect ongoing crew rotations on the space station, the arrival of European and Japanese cargo ships and to train Bowen to replace astronaut Timothy Kopra, the mission's lead spacewalker, after he was injured in a bicycle accident last month near his home in Houston.

"We had a very thorough review today," said Bill Gerstenmaier, director of space operations at NASA headquarters. "The teams have done a great job, I think we're ready to go next week."

He praised the NASA and contractor engineers and technicians who did the troubleshooting, analysis and repairs of Discovery's tank, one of the most challenging examples of shuttle surgery ever attempted so close to launch. Many members of the repair team were called in from Lockheed Martin's Michoud Assembly Facility near New Orleans where the giant tank was built. With only three more shuttle flights planned, the production line has been shut down.

"They did a phenomenal job of doing this testing and pulling the work together," Gerstenmaier said. "I couldn't be prouder of what they've done. ... A lot of these folks, some of them in the tank world, were laid off, they were already in other jobs and we called them back to do some of this work. ... There was no question about their dedication. They really want to see this vehicle fly."

The primary goals of the 133rd shuttle mission are to deliver critical spare parts, supplies and a final U.S. module to the International Space Station.

Assuming an on-time launch, Lindsey will guide Discovery to a docking at the station's forward port around 2:16 p.m. on Feb. 26. Two spacewalks are planned, on Feb. 28 and March 2, with attachment of the new storage module in between the EVAs on March 1. Discovery would undock from the station around 7:44 a.m. on March 5 and land back at the Kennedy Space Center around 12:44 p.m. on March 7.

But NASA managers and their Russian counterparts are considering a plan to add a day to Discovery's mission so a Russian Soyuz spacecraft, carrying station commander Scott Kelly, Alexander Kaleri and Oleg Skripochka, could undock, move away and capture photographs and video of the completed station with the shuttle attached, along with a full complement of Russian, European and Japanese cargo craft.

Assuming the fly-around is approved -- and no decisions are expected until after Discovery reaches the space station -- flight planners would insert a new flight day 10 into the crew's March 5 timeline for the Soyuz photo op. Discovery would undock the next day and land in Florida around 11:35 a.m. on March 8.

NASA originally hoped to launch Discovery on Nov. 1, but the flight was delayed to Nov. 5 by bad weather and technical problems.

The ship was fueled for launch Nov. 5, but the countdown was called off when sensors detected a gaseous hydrogen leak in a quick-disconnect fitting used to attach a vent line to the side of the tank. That problem was quickly resolved, but engineers also discovered cracks near the tops of two adjacent structural rib-like "stringers" near a flange in the external tank that supports the upper liquid oxygen tank. More cracks were found later, after Discovery was returned to NASA's Vehicle Assembly Building for more detailed inspections.

Tracing the manufacturing history of the tank, engineers discovered that most of the original 108 stringers in the "intertank" section that separates the tank's oxygen and hydrogen sections were made using an aluminum-lithium alloy from a lot that was more brittle than usual and more susceptible to temperature-induced fractures when the tank is loaded with super-cold propellants.

That weakness, engineers concluded, along with subtle manufacturing issues, were the most likely causes of the observed cracks.

In the most invasive repair of an external tank ever attempted, engineers installed structural stiffeners, called radius blocks, to better secure the top few inches of 105 stringers to prevent cracks from forming when the tips of the stringers are pulled inward due to the contraction of the liquid oxygen tank.

The goal was twofold: to ensure the tank's overall structural integrity and to prevent cracks that could cause foam insulation to pop off during the climb out of the dense lower atmosphere when debris impacts pose the greatest threat to Discovery's fragile heat shied.

The addition of the radius blocks more evenly distributes stresses in the stringers and reduces the strains on the top few fasteners.

The tank was designed to be structurally "fail safe" even if three adjacent stringers developed cracks. Data from a Dec. 18 fueling test, elaborate laboratory tests and an exhaustive engineering analysis showed the tank would remain structurally sound even if more than three stringers developed cracks greater than four inches in length as long as they were separated by undamaged stringers.

The tank's calculated factor of safety is not precisely known, but it is greater than one in all cases, meaning that even with extensive modifications and stringers that are more brittle than usual, the structure's strength is sufficient for flight.

Testing also showed cracks greater than four inches long were most likely to occur during fueling, when the hardware is "shocked" by extreme low temperatures and that any such fractures likely would cause cracks in the tank's insulation. With the radius block modifications, engineers do not expect such cracks to form. But during Discovery's countdown, cameras will be focused on the liquid oxygen flange area to look for any signs of insulation damage. If any cracks are seen, the countdown will be called off.

"This is probably one of the most difficult technical issues, I think, we've ever faced because the answers were not obvious," Lindsey said in a NASA interview. "It wasn't obvious what was wrong, why it was wrong, or how to fix it, and then you had the additional, if you will, pressure of the shuttle program winding up and we keep slipping and slipping and slipping.

"But to the space shuttle program's credit, they've really done due diligence on this one and really focused on the engineering, following the data, figuring out what was wrong. ... It's just been very impressive to watch them, not get rushed, focus on the data, focus on the engineering. When they didn't understand something, they did a lot of testing. You can write a thousand computer programs, but one test makes all the difference because that tells you what's really going on. So I think they've done a great job with it."

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CBS NEWS Coverage of Breaking Space News

10:30 AM, 02/11/11: Initial shuttle readiness review begins; Soyuz fly-around considered

By William HARWOOD
CBS News Space Consultant

NASA managers, engineers and contractors met Friday for a program-level review of the shuttle Discovery's ground processing and readiness to launch Feb. 24 on a long-delayed space station assembly mission. An executive-level fight readiness review is planned for Feb. 18.

Along with reviewing ground processing and external tank repairs, shuttle managers also are considering the possibility of staging what might be considered the ultimate photo op during Discovery's mission to deliver critical supplies and a final U.S. module to the space station.

The idea is to have a Russian Soyuz spacecraft undock so its three-man crew can photograph the station from a distance, showing the completed lab complex with the shuttle attached, along with Russian, European and Japanese cargo ships and crew capsules. Discovery's mission represents the last time a shuttle and all current types of visiting spacecraft will be present at the station before the shuttle fleet is retired later this year.

But the plan would require Russian approval and cooperation and it's not yet known if they will go along.

It is not a trivial undertaking. Anytime a manned spacecraft undocks, there is the possibility of a malfunction that could prevent a re-docking. In that case, the Soyuz and its three-man crew -- Soyuz TMA-01M commander Alexander Kaleri, Oleg Skripochka and Expedition 26 commander Scott Kelly -- would be forced to return directly to Earth, reducing the station's crew from six to three.

"This only hit people's radar at the end of last week," said one NASA manager. While video and still photos showing the completed space station with a shuttle attached would no doubt be spectacular, at least some agency insiders believe the risks outweigh the benefits. Others, seeing a chance to capture a defining image of the shuttle-station complex, are hopeful the Russians will approve.

The Russians staged a similar photo operation on July 4, 1995, when the shuttle Atlantis undocked after NASA's first linkup with the Russian Mir space station. Just before Atlantis separated, cosmonauts Anatoly Solovyev and Nikolai Budarin undocked in a Soyuz spacecraft and photographed the shuttle's departure from a distance of about 300 feet.

Just after Atlantis undocked, however, Mir's central computer shut down, apparently misinterpreting the jarring caused by the shuttle's separation as a fault. The cosmonauts successfully redocked and eventually rebooted the computer. Whether that experience might affect how the Russians view the current proposal remains to be seen.

NASA originally hoped to launch Discovery Nov. 1, but the flight was delayed because of bad weather and relatively minor technical snags. A launch attempt Nov. 5 was called off because of a gaseous hydrogen leak in a vent line attached to the ship's external tank. Then, during propellant draining operations, engineers discovered cracks in vertical rib-like stringers making up a central compartment in the huge tank.

Launch then was put on indefinite hold while engineers worked to repair the cracks and figure out what caused them in the first place. After a fueling test, extensive testing and additional inspections, NASA managers concluded the root cause was a combination of factors, including the effects of ultra-low temperature propellant, manufacturing issues and use of an aluminum-lithium alloy that was not as strong as expected.

Managers ultimately decided to install stiffeners on nearly all of the 108 stringers used in the so-called "intertank" section of the external tank. That work is complete, but tests and analysis have continued to make sure the modified tank has the required margin of safety.

In recent days, engineers have run into a variety of fresh problems with the gaseous hydrogen vent line that leaked Nov. 5, derailing Discovery's last launch attempt.

The leak was blamed on subtle alignment issues that, in the presence of low-temperature hydrogen gas, opened a leak path. Corrective actions were taken and during a fueling test Dec. 18, the fitting worked normally, without any significant leakage.

Because of trouble disconnecting the line later, technicians replaced a seal in the system this week. But during work to re-attach the vent line and rig it for launch, workers noticed unexpected movement in a component at the base of the umbilical plate that attaches the line to the side of the tank. Leak checks were successfully completed, but additional troubleshooting was planned.

In addition, a multi-blade tool called a "feeler gauge," similar to tools used to measure the gap in a spark plug, apparently came apart at the pad during work to rig the vent line fitting. Some of the tool's metal blades fell free and at least one of them hit Discovery's external tank. But a detailed photo analysis showed the damage was minor and no repairs were necessary.

In an unrelated issue, engineers preparing to service the system used to move the nozzles of the shuttle's two solid-fuel boosters heard an unexpected bang-like noise Monday. There were no obvious signs of trouble with the hardware and it's possible the sound was caused by a gust of wind slamming a door or an access panel closed on the launch pad gantry.

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CBS NEWS Coverage of Breaking Space News

By William HARWOOD
CBS News Space Consultant

With repairs to its external tank complete, engineers began hauling the shuttle Discovery back to launch pad 39A Monday evening for work to ready the ship for blastoff Feb. 24 on a flight to deliver critical spare parts, supplies and a final U.S. module to the International Space Station.

Carried by a powerful crawler-transporter, Discovery and its mobile launch platform began slowly rolling out of NASA's Vehicle Assembly Building at 7:58 p.m. EST (GMT-5), witnessed by scores of Kennedy Space Center workers who gathered nearby to watch what is expected to be Discovery's final trip to the pad. If all goes well, the shuttle will be "hard down" at the launch complex by around 3 a.m. Tuesday.

"I have full confidence we've done everything we need to do on that tank," Stephanie Stilson, the engineer in charge of Discovery's ground processing, told CBS News. "Seeing those guys work and knowing how hard they worked to do the modifications, I have confidence in the way the shuttle program works and the fact that they're always investigating and asking more questions, more so than I've ever heard in the past."

Shuttle program managers plan to conduct a flight readiness review Feb. 10, followed by an executive-level review by senior NASA managers Feb. 18. Assuming no additional problems develop, the agency hopes to restart Discovery's countdown at 3 p.m. Feb. 21, setting the stage for launch Feb. 24 at 4:50:19 p.m.

NASA originally hoped to launch Discovery on its 39th and final flight Nov. 1, but the mission was repeatedly delayed, first by relatively minor technical problems that pushed launch to Nov. 5 and then by a gaseous hydrogen leak in a vent arm attached to the external tank.

The hydrogen leak was quickly resolved, but engineers also discovered cracks in structural rib-like "stringers" in the shuttle's external tank that triggered what turned into a nearly four-month delay.

The stringers are used in the ribbed "intertank" compartment of the external tank that separates the liquid oxygen and hydrogen sections. Engineers initially found four stress-relief fractures in two adjacent stringers on the side of the tank facing the shuttle that apparently were the result of exposure to the extreme low temperature -- minus 423 degrees Fahrenheit -- of liquid oxygen.

Engineers repaired those cracks at the pad by splicing in pristine stringer segments and attaching "doublers" to provide additional strength.

After an instrumented fueling test Dec. 18, Discovery was hauled back to the Vehicle Assembly Building for X-ray inspections of the backside of the tank, which engineers could not carry out at the pad. Additional cracks were found in three stringers, prompting NASA managers to order installation of "radius-block" doublers on most of the remaining intertank stringers.

A detailed analysis of the cracks found to that point indicated manufacturing tolerance issues and problems with a specific batch of aluminum-lithium alloy used in most of the 108 intertank stringers that left them more brittle than usual and more susceptible to stress-relief fractures.

Testing showed the radius-block modifications would provide the required margin of safety, easing concerns about the tank's structural integrity and the possible loss of foam insulation during the climb out of the dense lower atmosphere that could pose a threat to the shuttle's fragile heat shield.

When all was said and done, the five cracked stringers were repaired using a combination of doublers and radius blocks and 94 were modified with radius blocks alone. Nine stringers were not modified, one because of access issues and eight others because they were made from a different lot of aluminum-lithium alloy.

As if the crack problem wasn't enough of a headache for NASA, one of Discovery's crew members -- flight engineer Timothy Kopra -- was injured in a bicycle mishap in Houston Jan. 15. He was replaced by veteran astronaut Stephen Bowen, who will take Kopra's place in two planned spacewalks.

Bowen and his crewmates -- commander Steven Lindsey, pilot Eric Boe, Nicole Stott, Michael Barratt and spacewalker Alvin Drew -- plan to fly to the Kennedy Space Center on Feb. 20 for the start of their countdown to launch.

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CBS NEWS Coverage of Breaking Space News

3:15 p.m. EST, 01/31/11/10 Update: Shuttle Discovery prepped for return to launch pad after external tank repairs

By William HARWOOD
CBS News Space Consultant

With repairs to its external tank complete, engineers geared up Monday to haul the shuttle Discovery back to launch pad 39A for work to ready the ship for blastoff Feb. 24 on a flight to deliver critical spare parts, supplies and a final U.S. module to the International Space Station.

Carried by a powerful crawler-transporter, Discovery and its mobile launch platform were expected to leave NASA's Vehicle Assembly Building around 8 p.m. EST (GMT-5) Monday for the 3.2-mile trip to the pad. If all goes well, the shuttle will be "hard down" at the launch complex by around 3 a.m. Tuesday.

Shuttle program managers plan to conduct a flight readiness review Feb. 10, followed by an executive-level review by senior NASA managers Feb. 18. Assuming no additional problems develop, the agency hopes to restart Discovery's countdown at 3 p.m. Feb. 21, setting the stage for launch Feb. 24 at 4:50:19 p.m.

NASA originally hoped to launch Discovery on its 39th and final flight Nov. 1, but the mission was repeatedly delayed, first by relatively minor technical problems that pushed launch to Nov. 5 and then by a gaseous hydrogen leak in a vent arm attached to the external tank.

The hydrogen leak was quickly resolved, but engineers also discovered cracks in structural rib-like "stringers" in the shuttle's external tank that triggered what turned into a nearly four-month delay.

The stringers are used in the ribbed "intertank" compartment of the external tank that separates the liquid oxygen and hydrogen sections. Engineers initially found four stress-relief fractures in two adjacent stringers on the side of the tank facing the shuttle that apparently were the result of exposure to the extreme low temperature -- minus 423 degrees Fahrenheit -- of liquid oxygen.

Engineers repaired those cracks at the pad by splicing in pristine stringer segments and attaching "doublers" to provide additional strength.

After an instrumented fueling test Dec. 18, Discovery was hauled back to the Vehicle Assembly Building for X-ray inspections of the backside of the tank, which engineers could not carry out at the pad. Additional cracks were found in three stringers, prompting NASA managers to order installation of "radius-block" doublers on most of the remaining intertank stringers.

A detailed analysis of the cracks found to that point indicated manufacturing tolerance issues and problems with a specific batch of aluminum-lithium alloy used in most of the 108 intertank stringers that left them more brittle than usual and more susceptible to stress-relief fractures.

Testing showed the radius-block modifications would provide the required margin of safety, easing concerns about the tank's structural integrity and the possible loss of foam insulation during the climb out of the dense lower atmosphere that could pose a threat to the shuttle's fragile heat shield.

When all was said and done, the five cracked stringers were repaired using a combination of doublers and radius blocks and 94 were modified with radius blocks alone. Nine stringers were not modified, one because of access issues and eight others because they were made from a different lot of aluminum-lithium alloy.

As if the crack problem wasn't enough of a headache for NASA, one of Discovery's crew members -- flight engineer Timothy Kopra -- was injured in a bicycle mishap in Houston Jan. 15. He was replaced by veteran astronaut Stephen Bowen, who will take Kopra's place in two planned spacewalks.

Bowen and his crewmates -- commander Steven Lindsey, pilot Eric Boe, Nicole Stott, Michael Barratt and spacewalker Alvin Drew -- plan to fly to the Kennedy Space Center on Feb. 20 for the start of their countdown to launch.

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CBS NEWS Coverage of Breaking Space News

By William HARWOOD
CBS News Space Consultant

Less than six weeks before launch, astronaut Timothy Kopra, injured in a bicycle accident Saturday, was removed from the crew of the shuttle Discovery Wednesday and replaced by astronaut Stephen Bowen, a veteran spacewalker who flew aboard the shuttle Atlantis last May. Despite the last-minute crew change, NASA officials say Bowen should be able to complete a hurried round of refresher training in time for blastoff around Feb. 24 as planned.

"As anybody would be this close to flight, he's disappointed, for sure," chief astronaut Peggy Whitson told reporters Wednesday, describing Kopra's reaction. "His crew made very tight bonds and so they are all very supportive of Tim. ... I think Steve will fit in well with this crew. He obviously doesn't have time to make a huge impact, he's going to just try to fill Tim's shoes as part of his role on the mission."

Kopra was named to the all-veteran crew of shuttle mission STS-133 in September 2009, along with commander Steven Lindsey, pilot Eric Boe, Nicole Stott, Michael Barratt and Alvin Drew. Kopra was assigned two key roles, serving as the flight engineer during launch and re-entry and the lead spacewalker for a pair of excursions with Drew.

Bowen, who completed two spacewalks last May during the most recent shuttle mission, is a Naval Academy graduate, a veteran submariner and father of three with two previous shuttle flights to his credit. He will replace Kopra for the two spacewalks planned for Discovery's fight.

"What we ended up doing in order to make it fit in the timeframe and not have to slip the launch or lose mission objectives is we decided to replace Tim's EVA (spacewalk) responsibilities with Steve Bowen," Whitson said.

"He's a very experienced EVA-er, five previous spacewalks and very capable in terms of qualifications in (NASA's spacesuit). We felt with a very few additional (training) runs, he could pick up the timeline Tim and Al had worked out together previously and be able to pull them off with only an additional two runs in the NBL (Neutral Buoyancy Laboratory training pool) for each of those two activities."

Kopra also served as Discovery's flight engineer, playing a critical role during ascent and entry. The flight engineer sits directly behind the shuttle commander and pilot, helping them monitor critical instruments and double-checking procedures, both for normal ascents and entries as well as emergency aborts.

Whitson said there was not enough time to train Bowen for two spacewalks and flight engineer duties and still make the next shuttle launch window. Instead, Drew will serve as flight engineer during ascent and Stott will take over for entry.

"This will require additional training on their part as well, but in the end we were able to get there with less than 45 technical hours per week of training," Whitson said. "We think it's a good plan, we think we've covered all the mission objectives with this training plan in the timeframe that we have."

Citing medical privacy issues, NASA officials will not discuss the extent of Kopra's injuries or provide details on what happened other than to say he was injured Saturday in a bicycle mishap near his home in Houston. Multiple sources have said he broke his hip, but Kopra has not yet made any public comment.

With only two and possibly three shuttle missions remaining before the fleet is retired, the bike accident marked a difficult personal setback for Kopra. In years past, an astronaut who had to miss a flight for medical reasons could look forward to being worked back into the crew rotation for launch on a future flight.

But there are no available seats on the remaining shuttle flights. Whitson said NASA is holding open the possibility of returning Kopra to Discovery's crew if the mission encounters a major delay, giving the astronaut time to recover, but that appears to be a long shot.

She said Kopra, who is recovering at home, plans to help his crew as much as possible during training and to be ready if he gets another chance. If Discovery stays on schedule, Kopra presumably would be available for launch to the space station aboard a future Russian Soyuz rocket, although station crews for the next few years are already set.

"When I went to his house to talk about this and our actions, his cat has a little hoop around her head to keep her from licking herself," Whitson said. "So he said the cat's in the penalty box and so am I. For getting hurt before the flight."

Astronauts with flight assignments have been replaced in the past for a variety of reasons, but NASA has never had to replace a shuttle crew member this close to launch.

Astronaut David Griggs, scheduled to serve as pilot of shuttle mission STS-33, was replaced after he was killed June 17, 1989, flying a vintage aircraft. Two shuttle commanders -- David Walker and Robert "Hoot" Gibson -- were removed from flights in 1990 for disciplinary reasons after they violated NASA flight rules in unrelated incidents.

Jeff Ashby was replaced as the pilot of STS-85 in 1997 because of a family illness and Mark Lee was replaced on the STS-98 crew in 2000 for undisclosed reasons.

Gus Loria and Carlos Noriega also were replaced in 2002 and 2004 respectively because of undisclosed medical issues and Karen Nyberg was replaced on the crew of STS-132 in 2009 because of a temporary medical condition.

The same day NASA announced Nyberg's replacement -- Aug. 11, 2009 -- the agency named the crew for shuttle mission STS-134, the flight after Discovery's upcoming mission. Just last week, NASA named a backup commander to train in place of astronaut Mark Kelly, the STS-134 commander. Kelly's wife, Rep. Gabrielle Giffords, was critically wounded in a Tucson shooting spree Jan. 8 and it's not yet known if he will be able to carry out his assignment aboard Endeavour, scheduled for launch April 19.

NASA's most famous crew replacement occurred in 1970 when Ken Mattingly, command module pilot for the Apollo 13 moon mission, was exposed to measles. He was replaced by Jack Swigert just three days before launch.

NASA trained backup crews for Mercury, Gemini and Apollo missions, as well as the first four shuttle missions, which were launched with two-man crews. But after that, with crews of six or seven astronauts, it was no longer practical to train backup shuttle crews and the practice came to an end.

Kopra, married and the father of two children, is a retired Army helicopter pilot who served in Operation Desert Shield and Desert Storm. He attended U.S. Naval Test Pilot School and was selected to join NASA's astronaut corps in 2000.

Kopra has flown in space once, blasting off aboard Endeavour July 15, 2009, and serving three months aboard the International Space Station before returning to Earth with the crew of the shuttle Discovery on Sept. 11, 2009. During his stay aboard the station, Kopra completed a five-hour two-minute spacewalk.

When the STS-133 crew was named in 2009, Discovery's flight was the shuttle program's final planned mission, following a post-Columbia Bush administration directive to finish the space station and retire the shuttle fleet by the end of fiscal year 2010.

That deadline was relaxed somewhat when Congress, worried about the possibility of schedule pressure on flight safety, promised an additional $600 million in funding to cover shuttle operations through the end of calendar year 2010. NASA managers later said internal cost-savings initiatives would allow shuttle operations to continue into early 2011 if necessary.

As it turned out, problems with a $2 billion particle physics experiment scheduled for launch aboard Endeavour during what was to have been the next-to-last fight in July 2010 forced NASA to revise the launch schedule.

Because of work to replace the powerful magnet in the particle physics experiment, Endeavour's flight slipped behind Discovery's, first moving to late November and eventually to late February. Discovery's flight, in turn, was delayed from mid September to Nov. 1, in part to accommodate work to modify a cargo transport module for permanent attachment to the space station.

After delays due to technical problems and bad weather, a launch attempt Nov. 5 was called off because of a gaseous hydrogen leak in an external tank vent line. That problem was resolved, but work to fix cracks in the ship's tank delayed ultimately delayed Discovery's launch to Feb. 24 and Endeavour's to April 19.

NASA hopes to close out the shuttle program with a final flight of the shuttle Atlantis in late June.

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CBS NEWS Coverage of Breaking Space News

1:10 PM, 01/19/11: Discovery astronaut Tim Kopra, injured in bike accident, replaced by Stephen Bowen

By William HARWOOD
CBS News Space Consultant

Less than six weeks before launch, astronaut Timothy Kopra, injured in a bicycle accident Saturday, was removed from the crew of the shuttle Discovery Wednesday and replaced by astronaut Stephen Bowen, a veteran spacewalker who flew aboard the shuttle Atlantis last May. Despite the last-minute crew change, NASA officials say Bowen should be able to complete a hurried round of refresher training in time for blastoff around Feb. 24 as planned.

Kopra was named to the all-veteran crew of shuttle mission STS-133 in September 2009, along with commander Steven Lindsey, pilot Eric Boe, Nicole Stott, Michael Barratt and Alvin Drew. Kopra was assigned two key roles, serving as the flight engineer during launch and re-entry and the lead spacewalker for a pair of excursions with Drew.

Bowen, who completed two spacewalks last May during the most recent shuttle mission, is a Naval Academy graduate, a veteran submariner and father of three with two previous shuttle flights to his credit. He will replace Kopra for the two spacewalks planned for Discovery's fight.

"Steve is an ideal candidate, and we have complete confidence he'll contribute to a fully successful STS-133 mission," chief astronaut Peggy Whitson said in a statement. "He has performed five prior spacewalks. That extensive experience, coupled with some adjustments to the spread of duties among the crew, will allow for all mission objectives to be accomplished as originally planned in the current launch window."

She apparently was referring to Kopra's role as flight engineer. Presumably, those tasks will be taken on by other crew members but details were not immediately available.

NASA officials will not discuss the extent of Kopra's injuries or provide details on what happened, citing medical privacy issues. But multiple sources said he broke his hip.

With only two and possibly three shuttle missions remaining before the fleet is retired, the bike accident marked a difficult personal setback for Kopra. In years past, an astronaut who had to miss a flight for medical reasons could look forward to being worked back into the crew rotation for launch on a future flight.

But there are no available seats on the remaining shuttle flights. NASA is holding open the possibility of returning Kopra to Discovery's crew if the mission encounters a major delay, giving the astronaut time to recover, but that appears to be a long shot.

"Tim is doing fine and expects a full recovery, however, he will not be able to support the launch window next month," Whitson said. "If for some unanticipated reason STS-133 slips significantly, it is possible that Tim could rejoin the crew."

If Discovery stays on schedule, Kopra presumably would be available for launch to the space station aboard a future Russian Soyuz rocket, although station crews for the next few years are already set.

Astronauts with flight assignments have been replaced in the past for a variety of reasons, but NASA has never had to replace a shuttle crew member this close to launch.

Astronaut David Griggs, scheduled to serve as pilot of shuttle mission STS-33, was replaced after he was killed June 17, 1989, flying a vintage aircraft. Two shuttle commanders -- David Walker and Robert "Hoot" Gibson -- were removed from flights in 1990 for disciplinary reasons after they violated NASA flight rules in unrelated incidents.

Jeff Ashby was replaced as the pilot of STS-85 in 1997 because of a family illness and Mark Lee was replaced on the STS-98 crew in 2000 for undisclosed reasons.

Gus Loria and Carlos Noriega also were replaced in 2002 and 2004 respectively because of undisclosed medical issues and Karen Nyberg was replaced on the crew of STS-132 in 2009 because of a temporary medical condition.

The same day NASA announced Nyberg's replacement -- Aug. 11, 2009 -- the agency named the crew for shuttle mission STS-134, the flight after Discovery's upcoming mission. Just last week, NASA named a backup commander to train in place of astronaut Mark Kelly, the STS-134 commander. Kelly's wife, Rep. Gabrielle Giffords, was critically wounded in a Tucson shooting spree Jan. 8 and it's not yet known if he will be able to carry out his assignment aboard Endeavour, scheduled for launch April 19.

NASA's most famous crew replacement occurred in 1970 when Ken Mattingly, command module pilot for the Apollo 13 moon mission, was exposed to measles. He was replaced by Jack Swigert just three days before launch.

NASA trained backup crews for Mercury, Gemini and Apollo missions, as well as the first four shuttle missions, which were launched with two-man crews. But after that, with crews of six or seven astronauts, it was no longer practical to train backup shuttle crews and the practice came to an end.

Kopra, married and the father of two children, is a retired Army helicopter pilot who served in Operation Desert Shield and Desert Storm. He attended U.S. Naval Test Pilot School and was selected to join NASA's astronaut corps in 2000.

Kopra has flown in space once, blasting off aboard Endeavour July 15, 2009, and serving three months aboard the International Space Station before returning to Earth with the crew of the shuttle Discovery on Sept. 11, 2009. During his stay aboard the station, Kopra completed a five-hour two-minute spacewalk.

When the STS-133 crew was named in 2009, Discovery's flight was the shuttle program's final planned mission, following a post-Columbia Bush administration directive to finish the space station and retire the shuttle fleet by the end of fiscal year 2010.

That deadline was relaxed somewhat when Congress, worried about the possibility of schedule pressure on flight safety, promised an additional $600 million in funding to cover shuttle operations through the end of calendar year 2010. NASA managers later said internal cost-savings initiatives would allow shuttle operations to continue into early 2011 if necessary.

As it turned out, problems with a $2 billion particle physics experiment scheduled for launch aboard Endeavour during what was to have been the next-to-last fight in July 2010 forced NASA to revise the launch schedule.

Because of work to replace the powerful magnet in the particle physics experiment, Endeavour's flight slipped behind Discovery's, first moving to late November and eventually to late February. Discovery's flight, in turn, was delayed from mid September to Nov. 1, in part to accommodate work to modify a cargo transport module for permanent attachment to the space station.

After delays due to technical problems and bad weather, a launch attempt Nov. 5 was called off because of a gaseous hydrogen leak in an external tank vent line. That problem was resolved, but work to fix cracks in the ship's tank delayed ultimately delayed Discovery's launch to Feb. 24 and Endeavour's to April 19.

NASA hopes to close out the shuttle program with a final flight of the shuttle Atlantis in late June.

=================================

9 PM, 01/15/11: Discovery astronaut Tim Kopra injured in bike accident

CBS NEWS Coverage of Breaking Space News

By William HARWOOD
CBS News Space Consultant

Space station veteran Timothy Kopra, scheduled for launch Feb. 24 aboard the shuttle Discovery, was injured in a bicycle accident Saturday, a NASA official said. The injury was not life threatening and the NASA official, citing medical privacy issues, provided no additional details. But multiple sources said Kopra may have broken his hip, raising the prospect of a significant impact to the already-delayed mission.

In training to serve as flight engineer for launch and entry, Kopra also is the mission's lead spacewalker for a pair of excursions outside the station. He and his crewmates have been in training since September 2009.

"Tim Kopra was injured today in a bicycle accident, but he will be OK," the NASA spokesman said in an email exchange. "However, there could be an impact to his mission duties for STS-133. That concern is still being evaluated. Further details of his injury are not available at this time due to concerns for his medical privacy."

NASA does not train backup crews and a replacement, even a recently flown veteran, would need time to rehearse spacewalk scenarios and receive mission-specific training for Discovery's flight. How long that might take, if required, and what impact it might have on the shuttle's launch date is not yet known.

With only three shuttle missions remaining before the fleet is retired, the accident marked a difficult personal setback for Kopra. In years past, an astronaut who had to miss a flight for medical reasons could look forward to being worked back into the crew rotation for launch on a future flight.

But with only two and possibly three missions left, there are no available seats and depending on the nature of his injury, Kopra could be forced to sit out the shuttle's closing stanzas.

Originally scheduled for launch Nov. 1, Discovery has been repeatedly delayed because of cracks in structural ribs, or stringers, in the ship's external tank. NASA managers announced last week that an engineering analysis had finally revealed the root cause of the cracks and that a relatively straight-forward modification was expected to clear the way for launch Feb. 24.

Discovery's delay, in turn, forced NASA to push back the shuttle Endeavour's launch on the following mission from late February to April 19. But any significant additional delay for Discovery would cause a domino-like slip for Endeavour as well.

Earlier this week, NASA announced that a backup commander -- Frederick Sturckow -- would begin training with Endeavour's crew in place of Endeavour commander Mark Kelly, whose wife, Rep. Gabrielle Giffords, was critically injured in a Tucson shooting spree Jan. 8. Kelly remains the mission commander and said in a statement Thursday "I am very hopeful that I will be in a position to rejoin my STS-134 crew members to finish our training."

Born in Austin, Texas, Kopra is a retired Army helicopter pilot who served in Operation Desert Shield and Desert Storm. He attended U.S. Naval Test Pilot School and was selected to join NASA's astronaut corps in 2000.

Kopra has flown in space once, blasting off aboard the shuttle Endeavour July 15, 2009, and serving three months aboard the International Space Station before returning to Earth with the crew of the shuttle Discovery on Sept. 11, 2009. During his stay aboard the station, Kopra completed a five-hour two-minute spacewalk.

Kopra was named to the crew of shuttle mission STS-133 in September 2009, along with commander Steven Lindsey, pilot Eric Boe, Alvin Drew, Michael Barratt and Nicole Stott. Barratt and Stott also are space station veterans.

At that time, NASA intended Discovery's flight to be the program's final voyage, following a Bush administration mandate to finish the space station and retire the shuttle fleet by the end of fiscal year 2010.

That somewhat arbitrary deadline was relaxed a bit when Congress, worried about the possibility of schedule pressure on flight safety, promised an additional $600 million in funding to cover shuttle operations through the end of calendar year 2010. NASA managers later said internal cost-savings initiatives would allow shuttle operations to continue into early 2011 if necessary.

As it turned out, problems with a $2 billion particle physics experiment scheduled for launch aboard Endeavour during the next-to-last fight in July 2010 forced NASA to revise the end-of-program shuttle manifest.

Because of work to replace the powerful magnet in the particle physics experiment, Endeavour's flight leap-frogged Discovery's, slipping to late November and eventually to Feb. 27, 2011. Discovery's flight, in turn, slipped from mid September to Nov. 1, in part to accommodate work to modify a cargo transport module for permanent attachment to the space station.

Discovery ran into a variety of technical problems, slipping from Nov. 1 to Nov. 5. A launch try that day was called off because of a gaseous hydrogen leak. That problem was resolved, but the crack issue surfaced in the wake of the scrub, eventually delaying Discovery's flight to Feb. 24 and Endeavour's to April 19.

NASA hopes to close out the shuttle program this summer with a final flight of the shuttle Atlantis.

=================================

CBS NEWS Coverage of Breaking Space News

12:30 PM, 01/13/11: NASA sets target launch dates for next two shuttle flights

By William HARWOOD
CBS News Space Consultant

NASA managers reviewed processing timelines Thursday and signed off on target launch dates for the next two space shuttle missions.

As expected, the agency hopes to launch the shuttle Discovery on mission STS-133, a flight to deliver needed supplies and a cargo storage module to the International Space Station, at 4:50:13 p.m. EST on Feb. 24. That target date assumes engineers complete repairs to structural ribs, or stringers, in the ship's external tank in time to move the shuttle back out to the launch pad around the end of the month.

Assuming an on-time launch, the flight plan calls for Discovery to dock with the space station around 1 p.m. on Feb. 26. Two spacewalks are planned, one on Feb. 28 and another on March 2, before undocking three days later and landing back at the Kennedy Space Center around noon on March 7.

Launch of the shuttle Endeavour on mission STS-134, a flight to deliver a $2 billion physics experiment to the station, is now targeted for liftoff at 7:48:34 p.m. EDT on April 19, setting up a docking two days later. Four spacewalks are planned for April 23, 25, 27 and 29. Landing at the Kennedy Space Center is planned for around 2:30 p.m. on May 3.

Only one additional shuttle flight is planned, a space station resupply mission with Atlantis that currently is targeted for launch June 28. NASA managers hope to fly that mission later in the summer if the budget permits, to leave the station as well supplied as possible before the fleet is retired.

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CBS NEWS Coverage of Breaking Space News

6 PM, 01/11/11: NASA zeroes in on root cause of shuttle tank cracks

By William HARWOOD
CBS News Space Consultant

Engineers believe they have zeroed in on the root cause of cracks in the shuttle Discovery's external tank, NASA officials said Tuesday. Installation of a relatively simple modification to the tops of the structural ribs, or stringers, where the ship's liquid oxygen tank is supported by a massive flange should resolve the problem once and for all, setting the stage for another launch attempt Feb. 24.

"We're on the road to bringing this tank to a hundred percent," said shuttle Program Manager John Shannon. "It's been two months of very vigorous activity, it took a lot of investigation to piece the different components of how this could be happening together, but I'm very confident we've finally got this figured out and we have a fix that's easy to implement and will be 100 percent effective."

Discovery's late February launch window opens the day after the European Space Agency's unmanned Automated Transfer Vehicle, loaded with supplies and equipment, reaches the International Space Station. The ATV is scheduled for launch from French Guiana on Feb. 15. Mission managers initially planned a docking on Feb. 26, but ESA, NASA and Russian managers have agreed to aim for a docking Feb. 23 instead. Assuming the ATV takes off and docks on time, Discovery would be set for another launch attempt at 4:50:13 p.m. EST on Feb. 24.

If all goes well, NASA hopes to have the shuttle Endeavour ready for launch on its final mission by around April 18. But planning for that flight is somewhat uncertain. Commander Mark Kelly's wife, Rep. Gabrielle Giffords, was shot in the head Saturday in Tucson by a gunman who killed six and wounded 13 others. Giffords remains in critical condition.

At a news briefing Tuesday to discuss the external tank investigation, Bill Gerstenmaier, director of space operations at NASA headquarters in Washington, declined to discuss Kelly's status, saying "out of respect to the family, we really are not ready to answer those questions today."

"We're going to let Mark decide really kind of what he needs to do," Gerstenmaier said. "We'll let his personal situation take focus on his activities and his thoughts and later when we know more about where (the Endeavour mission) sits and what our options are for Mark and his activities, we'll come talk to you at that time. ... Our hearts and prayers go out to the family and we're really thinking about Mark in everything we do."

The external tank crack problem first surfaced during fueling for a Nov. 5 launch attempt. Discovery's countdown was called off because of a gaseous hydrogen leak, a problem that was later resolved. But engineers also noticed a large crack in the external tank's foam insulation that developed during fueling. When the foam was removed later, four cracks were found in the "feet" of two adjacent ribs, or stringers, in a compartment that separates the tank's liquid oxygen and hydrogen sections.

The cracks presumably developed when the liquid oxygen tank was loaded with super-cold propellant, causing the flange that supports it to contract, pulling the top few inches of the intertank stringers inward. Tank components are designed to cope with that stress without breaking but for some reason, cracks developed near the tops of two stringers in Discovery's tank.

Engineers were immediately concerned, citing two potentially serious issues. Cracked stringers could result in foam insulation falling off during flight that could pose an impact threat to the shuttle's fragile heat shield. And if enough stringers failed, the structural integrity of the tank could be in question.

NASA launched a wide-ranging investigation to figure out the root cause of the cracks and what might be needed to correct the problem. A full-scale instrumented fueling test was carried out Dec. 17 to precisely map out the stresses acting on the tank during fueling. Discovery then was moved off the pad and back to the Vehicle Assembly Building for additional inspections.

Engineers then found four more cracks on the back side of the tank near the tops of three stringers, which could not be inspected at the launch pad. Like the first set of cracks, these were repaired by splicing in fresh stringer segments and attaching doublers for additional strength.

Believing built-in stresses from assembly likely caused the cracks, engineers proposed installing doublers on stringers to either side of massive solid rocket booster attachment panels that experience the most stress during flight.

But as it turned out, the issue was more complicated than first suspected. Engineers reviewing manufacturing records discovered that the aluminum-lithium alloy used in 78 of the 108 stringers in the intertank of Discovery's external tank came from a batch that had a mottled appearance, possibly the result of heat treatments during the alloy's formulation. Testing showed the material used in those stringers had just 65 percent of the expected fracture strength.

On New Year's Eve, Shannon said, engineers successfully re-created a crack using the same mottled aluminum-lithium alloy in a test rig that subjected it to the same sorts of stress the tank experiences during fueling.

"We absolutely have root cause and we have been able to show that through test," he said. "It's a combination of two factors. It's the low fracture toughness of the material, we have about 65 percent of the expected fracture toughness, combined with some assembly stresses that were built up in different areas.

"We know that because when we loaded the tank (with propellant), we put high stress on all of those stringers that had that low fracture toughness and we only had cracks in five of what we believe were 78 stringers. In looking at those stringers that cracked, we're seeing the evidence of those assembly stresses that combined with that low fracture toughness to cause the problem. So we have root cause and we have a fix that we're completely confident will eliminate those root causes."

The fix is installation of radius block plates all the way around the circumference of the upper intertank to beef up the under-strength stringers. The repair calls for engineers to remove the top few rivets holding the sides of each stringer in place. An aluminum plate -- a radius block -- is then placed over the stringer attachment "feet" and riveted into place. The idea is to lock the stringer flat against the side of the tank and make it less susceptible to the stresses that could cause fractures to develop.

Shannon said engineers are carrying out tests and analyses to make sure the repairs do not introduce any unintended consequences.

"We're proving that out through tests, we're looking at the strain, we're looking at the stiffness and verifying in the tests that material that does not have a radius block does not behave any different than one that does have a radius block," he said. "We're going through and modeling that through the entire tank and verifying we're not going to do any harm. Right now, it looks really good."

The repair work is expected to be completed by around Jan. 23. After that, engineers will move Discovery back to pad 39A for work to ready the ship for launch.

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CBS NEWS Coverage of Breaking Space News

By William HARWOOD
CBS News Space Consultant

Senior NASA managers Monday agreed to install stiffeners all the way around the shuttle Discovery's external tank to beef up structural ribs, or stringers, that are susceptible to cracks when exposed to ultra-low-temperature propellant. Engineers say the modifications can be completed in time to support at launch as early as Feb. 24, assuming the work goes smoothly no other major problems develop.

The so-called radius block plates will be attached to the top few inches of all the stringers making up the ribbed intertank that separates the external tank's liquid oxygen and hydrogen sections. Eight known cracks in five of the 108 stringers already have been repaired by splicing in fresh stringer segments and installing doublers for additional strength.

The cracks occurred near the top of the intertank where the stringers meet a large flange that supports the bottom of the liquid oxygen tank. Ultra-low-temperature liquid oxygen causes the tank to contract during fueling, which tends to pull the upper sections of the stringers inward.

The tank was designed to cope with that contraction, but it appears a specific lot of aluminum alloy used in this tank's construction provided less strength than expected. The tanks scheduled for use with the shuttle Endeavour in April and the shuttle Atlantis in June or July were built with alloys that are believed to have the proper strength.

To strengthen the rest of the stringers in Discovery's tank, radius block plates will be riveted into place over the anchors that hold the existing stringers in place. Testing indicates the modification will ensure the tank is up to the rigors of fueling and launch, giving it the safety margin needed to clear Discovery for flight.

But additional analysis will be needed to make sure the modifications do not introduce any unintended consequences. Sources said shuttle Program Manager John Shannon decided to press ahead with the repairs in parallel with work to flight certify the modifications. While that approach could lead to additional delays if the certification runs into problems, a senior manager said the tank could not be flown "as is" and that it made sense to proceed with repairs in parallel based on the results of testing to date.

In any case, engineers are proceeding cautiously in the wake of an incident in which a technician, working to drill out a stringer fastener so a cracked segment could be removed, inadvertently drilled into the underlying skin of the liquid oxygen tank. The damage was minimal and technicians were expected to simply buff out the blemish. But as a result, NASA managers have decided to leave each stringer's top-most fastener in place and to install radius blocks over fasteners two through seven instead.

"It's tricky working in the area when they're that close to the tank," an official said. "So they decided not to worry about fastener No. 1 on any of these stringers."

Shuttle engineers briefed senior management Monday on the status of the repairs and Bill Gerstenmaier, director of space operations at NASA headquarters, planned to brief John Holdren, director of the Obama administration's Office of Science and Technology Policy, later in the day. Gerstenmaier, shuttle Program Manager John Shannon and space station Program Manager Mike Suffredini were scheduled to hold a news conference Tuesday to discuss the status of the tank repair work and analysis.

Discovery originally was scheduled for launch Nov. 1 on a space station resupply mission. But the flight was repeatedly delayed by relatively minor technical problems and finally, on Nov. 5, by a gaseous hydrogen leak in a 7-inch vent line quick-disconnect fitting on the side of the external tank.

During work to drain the tank, engineers spotted cracks in its foam insulation near the top of the intertank compartment that separates the tank's hydrogen and oxygen sections. When the damaged foam was removed, four cracks were found in two adjacent stringers near the tank's left-side booster attachment thrust panel, which helps carry the load during launch.

After a fueling test Dec. 17 to collect additional data, Discovery was moved back to the Vehicle Assembly Building for additional inspections. Four more small cracks were found in three stringers on the back side of the tank, which could not be inspected at the launch pad.

Analysts have been unable to identify a single root cause explaining why the cracks formed in the first place, a key element in developing the engineering justification for proceeding with flight. But the radius block modification should provide the confidence needed to press ahead if no unintended consequences are identified.

Two launch windows were available in February, one opening on Feb. 3 and closing one week later and another opening Feb. 27 and closing March 6. NASA managers decided last week to pass up the first window to give engineers more time to assess the crack issue and to make a decision on whether to install the radius block stiffeners all the way around the tank.

The Feb. 27 opening of the second launch window was based on the planned Feb. 15 launch of a European Space Agency cargo spacecraft that was scheduled to dock at the space station on Feb. 26. But it appears the rendezvous timeline can be compressed, allowing NASA to launch Discovery as early as Feb. 24 if ESA's Automated Transfer Vehicle takes off on time and has no problems in orbit.

NASA and contractor managers and engineers are expected to set a new target launch date during a program requirements control board meeting Thursday. It's not yet clear how Discovery's launch delays will affect the following launch, a mission by the shuttle Endeavour to deliver a $2 billion physics experiment to the International Space Station.

It appears Endeavour will be delayed to mid April, but no decisions have been announced.

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CBS NEWS Coverage of Breaking Space News

11:30 PM, 1/6/11: NASA rules out early February launch for shuttle Discovery

By William HARWOOD
CBS News Space Consultant

NASA managers Thursday decided to give engineers additional time to assess external tank cracks and repair scenarios, ruling out an early February launch for the shuttle Discovery. The next shuttle launch window opens Feb. 27, but NASA is assessing whether it might be possible to move that up a few days.

Additional meetings are planned next week to review progress with already-ordered crack repairs, potential work to beef up other structural ribs, or stringers, in the external tank and the results of an on-going analysis into the root cause of the eight cracks discovered to date. A new target launch date is expected after a program requirements control board meeting Jan. 13 at the Johnson Space Center in Houston.

The next shuttle launch window, the one NASA managers ruled out Thursday, opens Feb. 3 and closes Feb. 10. The next window after that opens Feb. 27 and closes March 6.

The opening of the late-February window is based on plans by the European Space Agency to launch an unmanned cargo ship Feb. 15 to deliver critical supplies to the International Space Station. The normal flight plan calls for ESA's Automated Transfer Vehicle to dock with the lab complex on Feb. 26, clearing the way for Discovery to take off the next day.

If the ATV rendezvous profile can be compressed, it may be possible to launch Discovery a few days ahead of Feb. 27. But as of this writing, it's not yet clear whether that's a viable scenario.

NASA had hoped to launch Discovery on Nov. 1. But the flight was delayed by unrelated technical problems and finally, on Nov. 5, by a gaseous hydrogen leak in a 7-inch vent line quick-disconnect fitting on the side of the external tank.

During work to drain the tank, engineers spotted cracks in its foam insulation near the top of the intertank compartment that separates the tank's hydrogen and oxygen sections. When the damaged foam was removed, four cracks were found in two adjacent stringers near the tank's left-side booster attachment thrust panel, which helps carry the load during launch.

After an instrumented fueling test Dec. 17 to collect data on how exposure to ultra-low temperatures affects the intertank stringers, Discovery was moved back to the Vehicle Assembly Building for additional inspections. Four more small cracks on three stringers were found on the opposite side of the tank from the shuttle on Dec. 29.

The four cracks discovered in the wake of the Nov. 5 launch scrub were repaired by splicing in pristine stringer segments and attaching doublers to provide additional strength. The same repair was ordered for the cracks discovered in the VAB. Because engineers have not been able to determine a root cause, NASA managers also ordered so-called radius block stiffeners attached to another 32 stringers to either side of the two booster attachment thrust panels.

The intertank is built with 108 stringers and NASA managers are considering whether to install radius blocks all the way around the circumference of the external tank to ensure an adequate safety margin. While a single root cause of the cracks has not been determined, it appears the stringers in question were made using an aluminum alloy from a batch produced in 2002 that has a mottled appearance and may not be as strong as engineers expected.

With the addition of the radius block modification, testing indicates the tank's structural safety margin will be more than adequate. But engineers need to make sure the modifications have no unintended consequences and the analysis is not yet complete.

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CBS NEWS Coverage of Breaking Space News

7:55 PM, 1/3/11: Engineers consider beefing up all external tank 'stringers'

By William HARWOOD
CBS News Space Consultant

NASA managers Monday directed engineers to press ahead with work to repair four small cracks in three structural ribs, or stringers, in the shuttle Discovery's external tank that were discovered during X-ray inspections after Christmas. They also decided to add stiffeners to 34 other stringers to either side of the tank's massive booster attachment thrust panels that carry most of the load during launch.

Another meeting is planned for Thursday to discuss installing so called "radius-block" stiffeners to the tops of the remaining 69 stock stringers that form the familiar ribbed wall of the intertank that separates the external tank's oxygen and hydrogen sections. Attached over the anchors of the existing stringers, the radius-block doublers, along with repairs already made to the five stringers with cracks, would make the structure less susceptible to temperature-induced flexing when the tank is loaded with supercold liquid oxygen that can result in stress-relief fractures.

"That's an 'if' right now," a NASA official said of the additional stiffeners. "But I wouldn't be surprised if they came out of (the meeting) Thursday and said let's just do it. There's still going to be some uncertainty with these stringers and this modification removes some of that uncertainty."

If that decision is made, it is unlikely NASA could complete the work, repair the tank's foam insulation and get Discovery back out to the launch pad in time to support a launch attempt during the next available window, which opens Feb. 3 and closes Feb. 10. Work to beef up all 108 stringers at the top of the intertank almost certainly would delay Discovery's launch on a space station resupply mission to the next available window, which opens Feb. 27 and closes in early March.

Under that scenario, the next flight in the sequence, a mission by the shuttle Endeavour to deliver a $2 billion physics experiment to the International Space Station, likely would slip from around April 1 to around April 28, sources say. But no scheduling decisions have been made.

The crack issue cropped up Nov. 5 in the wake of a launch scrub caused by a gaseous hydrogen leak in an external tank vent line. While monitoring the tank, engineers noticed a long crack in the insulation over a stringer on the left side of the shuttle near a flange that supports the liquid oxygen tank. When the foam was removed, four cracks in two adjacent stringers were found.

The cracks were repaired by splicing in fresh stringer sections and installing doublers to add additional strength. At the same time, NASA launched an investigation into the potential causes and effects of temperature-induced cracks in the stringers and ordered tests designed to verify the structural integrity of the giant tank.

Shuttle managers also ordered a full-scale fueling test, pumping more than a half-million gallons of oxygen and hydrogen rocket fuel into the tank Dec. 17 to precisely measure thermal gradients and the stresses acting on the stringers as the oxygen tank and its support hardware contract in ultra-low temperatures. That has the effect of bending the tops of the stringers inward.

But the tank was designed to withstand those thermal effects and engineers have not yet found a single "root cause" to explain the eight cracks discovered to date. Tests are underway to deliberately over-stress stringers under laboratory conditions to map out failure modes and get a better understanding of the tank's structural integrity and its ability to withstand fueling and launch loads.

The testing also is expected to show whether the radius-block modification, a proven method of repairing cracks that develop during the tank's assembly, will provide the strength needed to clear Discovery for launch in the absence of a known root cause.

The four cracks discovered after Christmas will be repaired the same way the original four were fixed, by splicing in undamaged stringer sections and attaching doublers. The radius-block modification calls for removing the rivets holding the upper sections of stringers in place, installing the stiffeners to either side of each stringer and then re-installing the rivets.

The external tank scheduled for use with Endeavour is an older model that was damaged during Hurricane Katrina and later upgraded to include post-Columbia safety improvements. That tank, ET-122, was built using different materials that do not have a history of cracks.

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CBS NEWS Coverage of Breaking Space News

By William HARWOOD
CBS News Space Consultant

KENNEDY SPACE CENTER, FL--Engineers examining the shuttle Discovery's external tank in the Vehicle Assembly Building have found four more small cracks in three structural ribs, or stringers, on the opposite side of the tank from the orbiter that could not be inspected at the launch pad. Four cracks on the shuttle side of the tank were repaired earlier, and it's not yet clear what, if any, additional work might be needed to develop "flight rationale" for another launch attempt as early as Feb. 3.

NASA managers met Thursday to review the on-going tank analysis and to discuss potential modifications to beef up the stringers to either side of the tank's massive booster-attachment thrust panels that experience the most stress during fueling and launch. All of the cracks found to date are located on stringers to either side of the left thrust panel.

But senior managers deferred any decisions about additional modifications pending further analysis of the newly discovered cracks. Shuttle Program Manager John Shannon told engineers to repair the cracks using the same techniques employed to fix the four found after the Nov. 5 launch try. That work will take two to three days to complete. Another review is planned for Monday.

If the modifications are ordered and no other major problems develop, NASA could roll Discovery back to launch pad 39A around Jan. 14 for work to ready the ship for another launch try Feb. 3.

But an on-going analysis of structural safety margins is not yet complete and it's not yet clear how the latest cracks might play into that discussion. Laboratory tests of stringers using mockups of external tank hardware to determine worst-case loads and failure modes are expected to begin next week.

NASA managers had hoped to launch Discovery on a space station resupply mission -- the orbiter's 39th and final flight -- on Nov. 1. But the launching was repeatedly delayed by relatively minor technical problems and finally, on Nov. 5, by a gaseous hydrogen leak in a 7-inch vent line quick-disconnect fitting on the side of the external tank.

During work to drain the tank, engineers spotted cracks in its foam insulation near the top of the intertank compartment that separates the tank's hydrogen and oxygen sections. When the damaged foam was removed, four cracks were found in two adjacent stringers near the tank's left-side booster attachment thrust panel, which helps carry the load during launch.

The cracks were repaired by splicing in replacement sections, along with so-called doublers to provide additional strength. But analysts have been unable to identify a single root cause explaining why the cracks formed in the first place, a key element in developing flight rationale showing the tank is structurally sound and able to withstand the rigors of fueling and launch.

To collect additional data, sophisticated X-ray-like scanners were used to examine the stringers on the side of the tank facing the shuttle -- the side engineers could access at the launch pad -- to make sure no additional cracks were present. None were found.

Dozens of strain gauges and temperature sensors then were attached to the tank for a full-scale fueling test Dec. 17. The sensor readings showed the stresses and strains experienced by the tank after it was loaded with more than a half-million gallons of supper-cold propellants matched up well with computer models as did the measured shrinkage of critical components. No sudden changes were noted in the stress data that might indicate additional stress-relief cracks.

To make the test as realistic as possible, the countdown was carried to the T-minus 31-second mark and the hydrogen and oxygen tanks were pressurized as they would be for a real launch. But pressurization had no major effect on the strain gauge data.

Based on data collected to that point, it appeared the cracks were the result of manufacturing issues that resulted in a build up of stress in the stringers in question that reached the breaking point when the tank was loaded with propellants Nov. 5. Overall, officials said, the data indicate the tank's design is robust and that the structure is as strong or stronger than initially believed.

But the shuttle's service gantry does not provide access to the back side of the external tank at the launch pad. To carry out additional X-ray inspections, Discovery was hauled back to the Vehicle Assembly Building Dec. 22. The four new cracks were spotted Wednesday on stringers six, seven and 11 on panel No. 6. Facing the left side of the tank, panel 6 is located to the left of the left-side booster thrust panel. The previously discovered cracks were located on panel No. 2, located on the right side of the left-side thrust panel.

All of the newly discovered cracks were smaller than the four found in the wake of the Nov. 5 launch attempt, measuring between 2.3 inches and 4 inches long.

Engineers already were considering the installation of special stiffeners on the 36 stringers -- nine to either side of the two thrust panels -- that experience the most stress during fueling and launch. All of the cracks discovered to date would be included in any such repair.

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CBS NEWS Coverage of Breaking Space News

04:20 PM, 12/30/10 Update: Inspections reveal four more cracks in shuttle tank; analysis continues

By William HARWOOD
CBS News Space Consultant

Engineers examining the shuttle Discovery's external tank in the Vehicle Assembly Building have found four more small cracks in three structural ribs, or stringers, on the opposite side of the tank from the orbiter that could not be inspected at the launch pad. Four cracks on the shuttle side of the tank were repaired earlier, and it's not yet clear what, if any, additional work might be needed to develop the "flight rationale" needed for another launch attempt as early as Feb. 3.

NASA managers met Thursday to review the on-going tank analysis and to discuss potential modifications to beef up the stringers to either side of the tank's massive booster-attachment thrust panels that experience the most stress during fueling and launch. All of the cracks found to date are located on stringers to either side of the left thrust panel.

If the modifications are ordered and no other major problems develop, NASA managers hope to roll Discovery back to launch pad 39A around Jan. 14 for work to ready the ship for another launch try Feb. 3.

But an on-going analysis of structural safety margins is not yet complete and it's not yet clear how the latest cracks might play into that discussion. Laboratory tests of stringers using mockups of external tank hardware to determine worst-case loads and failure modes are expected to begin next week.

NASA managers had hoped to launch Discovery on a space station resupply mission -- the orbiter's 39th and final flight -- on Nov. 1. But the launching was repeatedly delayed by relatively minor technical problems and finally, on Nov. 5, by a gaseous hydrogen leak in a 7-inch vent line quick-disconnect fitting on the side of the external tank.

During work to drain the tank, engineers spotted cracks in its foam insulation near the top of the intertank compartment that separates the tank's hydrogen and oxygen sections. When the damaged foam was removed, four cracks were found in two adjacent stringers near the tank's left-side booster attachment thrust panel, which helps carry the load during launch.

The cracks were repaired by splicing in replacement sections, along with so-called doublers to provide additional strength. But analysts have been unable to identify a single root cause explaining why the cracks formed in the first place, a key element in developing flight rationale showing the tank is structurally sound and able to withstand the rigors of fueling and launch.

To collect additional data, sophisticated X-ray-like scanners were used to examine the stringers on the side of the tank facing the shuttle -- the side engineers could access at the launch pad -- to make sure no additional cracks were present. None were found.

Dozens of strain gauges and temperature sensors then were attached to the tank for a full-scale fueling test Dec. 17. The sensor readings showed the stresses and strains experienced by the tank after it was loaded with more than a half-million gallons of supper-cold propellants matched up well with computer models as did the measured shrinkage of critical components. No sudden changes were noted in the stress data that might indicate additional stress-relief cracks.

To make the test as realistic as possible, the countdown was carried to the T-minus 31-second mark and the hydrogen and oxygen tanks were pressurized as they would be for a real launch. But pressurization had no major effect on the strain gauge data.

Based on data collected to that point, it appeared the cracks were the result of manufacturing issues that resulted in a build up of stress in the stringers in question that reached the breaking point when the tank was loaded with propellants Nov. 5. Overall, officials said, the data indicate the tank's design is robust and that the structure is as strong or stronger than initially believed.

But the shuttle's service gantry does not provide access to the back side of the external tank at the launch pad. To carry out additional X-ray inspections, Discovery was hauled back to the Vehicle Assembly Building Dec. 22. The four new cracks were spotted Wednesday on stringers six, seven and 11 on panel No. 6. Facing the left side of the tank, panel 6 is located to the left of the left-side booster thrust panel. The previously discovered cracks were located on panel No. 2, located on the right side of the left-side thrust panel.

All of the newly discovered cracks were smaller than the four found in the wake of the Nov. 5 launch attempt, measuring between 2.3 inches and 4 inches long.

Engineers already were considering the installation of special stiffeners on the 36 stringers -- nine to either side of the two thrust panels -- that experience the most stress during fueling and launch. All of the cracks discovered to date would be included in any such repair.

=================================

CBS NEWS Coverage of Breaking Space News

03:00 PM, 12/17/10 Update: Shuttle tanking test complete; instrumentation worked well with no major surprises

By William HARWOOD
CBS News Space Consultant

Data from temperature sensors attached to the skin of the shuttle Discovery's external tank closely matched predictions from computer models, engineers said Friday as a critical fueling test drew to a close, and no unusual stresses were noted from strain gauges on or near structural ribs, or stringers, that cracked during a Nov. 5 launch attempt.

The fueling test began at 7 a.m. EST (GMT-5) and ended at 2:25 p.m. with the countdown holding at the T-minus 31-second mark. The liquid hydrogen and oxygen tanks were pressurized as they would be in a real launch countdown to collect additional data on the tank's performance.

After draining the propellants, engineers planned to move a rotating gantry back around the space shuttle around 10:30 p.m. in preparation for starting work to ready the ship for roll back to the Vehicle Assembly Building early Tuesday. Once in the VAB, X-ray equipment will be used to look for any signs of cracks or other damage that might have escaped detection to this point.

NASA managers plan to meet Tuesday to discuss whether to order installation of structural stiffeners on 36 stringers, nine to either side of the two booster-attachment thrust panels, that experience the most stress during launch. If all goes well and no other major problems are found, NASA hopes to haul Discovery back to the launch pad in mid January for work to ready the ship for launch Feb. 3 on a space station resupply mission.

A detailed assessment of the data collected during today's test is not expected until later. But a senior shuttle manager said the instrumentation operated normally throughout the test, collecting data to better understand how the tank responds to the shock of ultra-low temperature propellants. An inspection by engineers at the launch pad found no obvious problems, reporting that freshly sprayed foam insulation over the sensors performed well.

One of two stereo cameras focused on thousands of small dot-like targets to detect any movement in the structure due to shrinkage or other factors apparently moved during the test and it's not yet clear if those data will be useful. The other camera apparently worked well.

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CBS NEWS Coverage of Breaking Space News

10:30 AM, 12/17/10 Update: External tank full, in 'stable replenish' mode; no obvious problems seen

By William HARWOOD
CBS News Space Consultant

The shuttle Discovery's external tank has been fully loaded with more than a half-million gallons of liquid oxygen and hydrogen rocket fuel. The three-hour fueling procedure began at 7 a.m. EST and ended at 9:59 a.m. when both the hydrogen and oxygen tanks were both in "stable replenish" mode. So far, no problems have been seen. A hydrogen vent line that leaked during a Nov. 5 launch attempt is operating normally today and engineers have not spotted any problems with the tank's foam insulation.

Launch Director Mike Leinbach said engineers are recording data from strain gauges and temperature sensors, but it will take time to evaluate the information and draw any conclusions about the tank's structural integrity and the effects of ultra-low temperatures on vertical ribs, or stringers, where cracks developed during fueling for the November launch attempt.

"Everything's going extremely well," said Leinbach. "We got into tanking on time and we're processing through the standard tanking procedure, not doing anything different to fill up the tank today. And everything's going really, really well. The ground umbilical carrier plate is working fine, no leaks there. That was one of our major objectives and that guy's performing perfectly fine now.

"We haven't seen any issues with the foam. We've talked to the guys looking at the sensors and the data's being processed right now. Too early to draw any conclusions, of course, but we're getting great data from the tank. So we're pressing on, we feel good about it. ... We're looking forward to the real thing. Hopefully in February we'll do that."

Just like with a real launch countdown, a team of technicians was sent to the pad 39A after the tank was full to begin a close-up inspection, looking for any signs of trouble with the foam insulation. During the Nov. 5 launch attempt, cracks in two stringers making up the ribbed intertank section caused a large crack to appear in the tank's foam insulation.

The stringer cracks were repaired by splicing in undamaged segments and then bolting on doublers to provide additional strength. But engineers looking into what caused the cracks have not found an obvious "smoking gun." Based on an exhaustive investigation, it appears the cracks were the result of a "stack up" of tolerance problems during the tank's construction that resulted in pre-loaded stress in the hardware. Today's fueling test may help engineers confirm that hypothesis.

"So we have stringers instrumented in the repair area so we can look and see how that repair performs under a cryo load," said Mike Moses, the shuttle integration manager at the Kennedy Space Center. "We have stringers instrumented next to that repair that aren't damaged so we can see how they perform. That'll give us some information about the general area to see if there are any non-linearities. And then on the opposite side of the tank, we've instrumented stringers to kind of go to a control type theory to say over here in a completely different area, here's how the tank performs.

"Really what we want to look for, in additional to the details, it's really that big picture," he said. "Does the left side and the right side of the tank compare to each other, do both sides perform the way the models show they would?

"We're looking for non linearities, is something obviously not tracking what we think it's going to, are the temperature profiles what we think, is there a spike in stress or strain that we do not expect to see? That would be an indication that there might be a different problem other than the stringer itself having a flaw or a defect that would put us in that second family where the stringer was the victim here and not the cause.

"None of our experts believe that to be the problem, none of our analysis or data mining to date shows that that's going to be the case. This tanking test hopefully will give us the final set of data that lets us kind of declare that to be true."

Engineers are hopeful the instrumented fueling test, along with exhaustive analysis and additional testing will clear the way to launch in early February even in the absence of a single obvious cause of the cracks.

"It looks like what we probably had happen was during assembly we introduced stress such that this part was kind of pre-loaded with some stress and then the extra stress of cryo loading was enough to then break it and exceed its capacity," Moses said.

When the stringers are attached to the skin of the intertank, he said, "you kind of clamp it together. There could be gaps between the parts such that when you then rivet it up with ... something like a 5,000-pound load, you could trap a lot of that force into the part if there's a gap.

"When you stack up that there might have been a gap there, and you stack up that you might have clamped it down a little too hard, which made the feet splay out a little, and then when you look at the stringer itself, this particular stringer ... is like a tenth of an inch farther up the tank than the other stringers. These things are pre-formed with a bend in them, that bend is now in a different place than it was supposed to be. So you have these groupings of things that if they line up on you could cause a problem.

"We're not probably going to come out of here with a smoking gun, but we're going to come out of here with a family of failures and we're going to have a lot of testing to then make sure we're not fooling ourselves."

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CBS NEWS Coverage of Breaking Space News

07:30 AM 12/17/10 Update: Shuttle fueling test begins

By William HARWOOD
CBS News Space Consultant

Working by remote control, engineers began pumping liquid oxygen and hydrogen through transfer lines to the space shuttle Discovery at 7 a.m. EST (GMT-5) Friday to begin a planned seven-and-a-half-hour test to verify the structural integrity of the ship's external tank and to test the strength of repairs to two cracked ribs, or stringers, that were discovered after a Nov. 5 launch scrub.

The propellants, flowing through transfer lines to the shuttle's aft engine compartment, through main engine plumbing and then into the external tank, will subject the tank's components to ultra-low temperatures that will be measured by thermocouples mounted on the tank's skin.

Strain gauges will measure the stresses acting on the stringers near two booster attachment thrust plates, including the two ribs that cracked during fueling Nov. 5. Those data will be used to verify the tank's ability to withstand the thermal stresses of fueling, confirm the strength of the repaired stringers and help analysts validate ascent safety margins.

The tanking test also will allow engineers to verify the performance of a 7-inch gaseous hydrogen vent line that leaked during fueling Nov. 5. The vent line quick-disconnect hardware was replaced and alignment problems thought to have caused the leak were corrected.

Discovery will be hauled back to the Vehicle Assembly Building Tuesday for additional X-ray inspections and possible modifications to beef up 36 stringers -- nine on either side of the two thrust plates where the shuttle's solid-fuel boosters are attached. If no other major problems are found, NASA hopes to move the shuttle back to the pad in mid January for work to ready the ship for launch Feb. 3 on a space station resupply mission.

Here is the timeline for today's activity:

EST........EVENT

01:00 AM...Final fueling preps
03:00 AM...Pad clear

06:00 AM...Begin a one-hour built-in hold
07:00 AM...Resume countdown

07:00 AM...Liquid oxygen/hydrogen transfer line chill down begins
07:10 AM...Liquid hydrogen slow fill begins
07:40 AM...Liquid oxygen slow fill begins
07:45 AM...Hydrogen engine cutoff sensors "wet"
07:50 AM...Liquid oxygen fast fill begins
08:00 AM...Liquid hydrogen fast fill begins
09:15 AM...Liquid hydrogen topping (98 percent full)
09:45 AM...Liquid hydrogen replenish
10:00 AM...Liquid oxygen stable replenish

10:00 AM...Begin a one-hour built-in hold
10:00 AM...Final inspection team at the launch pad
11:00 AM...Resume countdown

01:00 PM...Final inspection team departs launch pad

01:40 PM...Begin a 10-minute hold at T-minus 20 minutes
01:50 PM...NASA test director briefing
01:50 PM...Resume countdown

02:01 PM...Begin a 10-minute hold at T-minus 9 minutes
02:05 PM...NASA test director launch status verification
02:11 PM...Resume countdown

02:11 PM...Ground launch sequencer auto sequence start
02:16 PM...Terminate liquid oxygen replenish
02:18 PM...Tank pressurization
02:19 PM...Begin a five-minute hold at T-minus 31 seconds
02:24 PM...Fueling test ends
02:50 PM...Liquid oxygen drain begins
02:55 PM...Liquid hydrogen drain begins

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CBS NEWS Coverage of Breaking Space News

05:15 PM 12/16/10 Update: Shuttle Discovery set for fueling test

By William HARWOOD
CBS News Space Consultant

Engineers working through a modified shuttle launch countdown are preparing to pump a half-million gallons of supercold liquid oxygen and hydrogen rocket fuel into the shuttle Discovery's external tank Friday to collect data needed to assess the tank's structural integrity in the wake of cracked ribs, or stringers, found after a Nov. 5 launch attempt.

Assuming the test goes well and no other problems develop, Discovery will be hauled back to the Vehicle Assembly Building next week for additional X-ray inspections and possible modifications. NASA hopes to move Discovery back to pad 39A in mid-January for work to ready the ship for another launch attempt as early as Feb. 3.

The cracks in question are located near the top of the external tank's ribbed intertank section where a large flange supports a liquid oxygen tank. Four cracks were found in two adjacent stringers near one of the tank's two booster-attachment thrust panels. The cracks were repaired by splicing in undamaged sections and installing so-called "doublers" to add additional strength.

But engineers are still working to pin down what caused the cracks in the first place. Without a confirmed root cause, analysts cannot rule out the possibility that additional cracks could form, possibly compromising the tank's structural integrity or resulting in the loss of foam insulation that could pose an impact threat to the shuttle's fragile heat shield during ascent.

While inspections using X-ray equipment should catch any pre-existing cracks, initial results of testing using external tank hardware subjected to predicted launch day loads indicates a loss of structural safety margin if two or three adjacent stringers in critical areas were damaged enough to be considered "failed."

As a result, engineers are assessing so-called "radius-block" reinforcements that could be attached to beef up the 36 stringers on either side of the thrust panels where the shuttle's two solid-fuel boosters attach. Those stringers, nine on either side of both thrust panels -- including the two that were repaired -- experience the most stress and are most prone to assembly problems during manufacturing.

The fueling test was ordered to precisely characterize the stresses acting on the stringers before launch, when the tank is subjected to extremely low temperatures. Engineers cut away insulation and installed 21 stain gauges and 39 temperature sensors, or thermocouples, on and near the repaired stringers on the left side of the space shuttle. Another 18 strain gauges and 21 thermocouples were attached to the skin of the tank near the right-side thrust panel. Engineers then re-applied foam insulation.

The sensors will measure the stresses acting on the stringers as liquid oxygen, at minus 298 degrees Fahrenheit, is pumped into the tank along with liquid hydrogen, at minus 423 degrees. As the tanks contract in the ultra-low temperatures, the stringers will be subjected to bending stresses near the oxygen and hydrogen tank flanges. They are designed for that, but analysts want to characterize exactly how much stress might be present and map out thermal gradients in the area.

The fueling test has four primary goals:

-- Gather full-scale environmental data to help validate sub-scale testing and analysis

-- Determine if there are structural issues with the intertank that are the result of generic manufacturing issues as opposed to isolated problems with specific stringers

-- Verify that the repaired stringers perform normally during fueling

-- Verify that a gaseous hydrogen vent line attached to the side of the tank is leak free. A quick-disconnect fitting leaked during fueling Nov. 5, triggering a launch scrub

To make the fueling test as realistic as possible, the tank will be loaded with propellants following roughly the same timeline used for an actual launch:

EST........EVENT

01:00 AM...Final fueling preps
03:00 AM...Pad clear

06:00 AM...Begin a one-hour built-in hold
07:00 AM...Resume countdown

07:00 AM...Liquid oxygen/hydrogen transfer line chill down begins
07:10 AM...Liquid hydrogen slow fill begins
07:40 AM...Liquid oxygen slow fill begins
07:45 AM...Hydrogen engine cutoff sensors "wet"
07:50 AM...Liquid oxygen fast fill begins
08:00 AM...Liquid hydrogen fast fill begins
09:15 AM...Liquid hydrogen topping (98 percent full)
09:45 AM...Liquid hydrogen replenish
10:00 AM...Liquid oxygen stable replenish

10:00 AM...Begin a one-hour built-in hold
10:00 AM...Final inspection team at the launch pad
11:00 AM...Resume countdown

01:00 PM...Final inspection team departs launch pad

01:40 PM...Begin a 10-minute hold at T-minus 20 minutes
01:50 PM...NASA test director briefing
01:50 PM...Resume countdown

02:01 PM...Begin a 10-minute hold at T-minus 9 minutes
02:05 PM...NASA test director launch status verification
02:11 PM...Resume countdown

02:11 PM...Ground launch sequencer auto sequence start
02:16 PM...Terminate liquid oxygen replenish
02:18 PM...Liquid oxygen tank pressurization
02:19 PM...Liquid hydrogen tank pressurization
02:20 PM...Begin a five-minute hold at T-minus 31 seconds
02:24 PM...Fueling test ends
02:50 PM...Liquid oxygen drain begins
02:55 PM...Liquid hydrogen drain begins

Along with measuring stresses and temperatures, stereo cameras will be focused on thousands of small dots painted on the tank to document subtle changes indicative of internal components shrinking on exposure to low temperatures.

After the test is complete, cabling will be removed and Discovery will be hauled back to the Vehicle Assembly Building Dec. 21. After Christmas, engineers will carry out X-ray inspections all the way around the circumference of the tank at both the liquid hydrogen and oxygen flanges at the top and bottom of the intertank section. The instrumentation is capable of spotting even small cracks beneath the foam insulation.

Repair crews will remove the strain gauges and thermocouples and apply fresh foam insulation. And they likely will be directed to attach the radius block doublers near the thrust panels to provide an additional safety margin.

Engineers say the reinforcement hardware can be installed in time to support another launch attempt Feb. 3. But that assumes no problems emerge from the tanking test and that work to remove instrumentation and repair the tank's foam goes smoothly.

=================================

CBS NEWS Coverage of Breaking Space News

06:10 PM 12/13/10 Update: Shuttle fueling test on tap Friday, weather permitting

By William HARWOOD
CBS News Space Consultant

The shuttle Discovery's external tank will be loaded with supercold rocket propellants as early as Friday in a critical test to help engineers understand what might have caused cracks in two structural ribs, or stringers, during a Nov. 5 launch attempt. The test also will show whether the repaired stringers can withstand the thermal stresses of fueling and help NASA managers develop "flight rationale" before proceeding to another launch attempt around Feb. 3.

Engineers initially hoped to carry out the tanking test Wednesday, but cold weather and high winds slowed work to install sensors and cabling. With overnight lows predicted to be near freezing for the next two days, additional delays are possible.

Hoping for the best, NASA managers and engineers met Monday and agreed that after the test, whenever it takes place, the shuttle "stack" will be hauled back to the Vehicle Assembly Building for additional inspections, and possible repairs, before returning to pad 39A in mid January for work to ready the ship for launch.

To make the fueling test as realistic as possible, the tank will be fully loaded with a half-million gallons of liquid oxygen, at minus 298 degrees Fahrenheit, and hydrogen rocket fuel, at minus 423 degrees, starting at 7 a.m. EST (GMT-5). The fueling timeline will be similar to the one used for an actual launch, including several built-in holds and an on-pad inspection. As the countdown ticks into its final minutes, the tanks will be pressurized as they would for a real launch, subjecting the hardware to additional stress.

The countdown clock will hold at the T-minus 31-second mark for five minutes before cutoff and detanking operations.

Thirty-nine strain gauges and 50 temperature sensors have been attached to the tank near the upper section of the ribbed "intertank" where vertical stringers meet a flange that supports the base of the liquid oxygen tank. Twenty-one of the strain gauges are mounted near the two cracked stringers to the left of the shuttle, along with numerous thermocouples. The rest are positioned in a similar location on the right side of the intertank flange facing the orbiter.

To attach the sensors directly to the tank's structure, technicians first had to remove foam insulation in the targeted areas. Fresh foam must be reapplied before the fueling test but that work has been slowed by cold weather and a requirement for ambient temperatures of at least 75 degrees in makeshift access platform tents to make sure the insulation cures properly.

Whenever the test takes place, the sensors should help engineers map out temperature gradients in critical components as well as the stresses imparted by thermal contraction of the aluminum-lithium alloy used in the stringers and panels making up the intertank. They also will provide insight into the health of the two repaired stringers that cracked during fueling Nov. 5.

At the same time, stereo cameras will be focused on thousands of small targets, or dots, on the outside of the tank to precisely measure deflections in the structure of the tank as it responds to cryogenic temperatures.

As a side benefit of the fueling test, engineers will confirm that a 7-inch gaseous hydrogen vent line attachment on the side of the external tank is functioning properly after repairs to correct a presumed alignment problem. The Nov. 5 launch attempt was called off because of a leak in the vent line quick-disconnect fitting. The cracks were discovered later, after engineers noticed a large fissure in the foam insulation near the top of the intertank.

When the damaged foam was removed, four cracks were found in two adjacent stringers. The damaged sections were replaced and doublers were installed to add additional strength. Sophisticated X-ray devices then were used to inspect other stringers around the circumference of the intertank on the side facing the shuttle. No other problems were found.

The lithium-aluminum alloy used in the so-called super-lightweight tanks is known to be relatively brittle and cracks are not unusual. But Discovery's are the first known cracks to develop under cryogenic conditions at the launch pad and engineers do not yet understand the root cause.

The instrumented fueling test, ongoing computer analysis and off-site testing with high-fidelity mockups are intended to collect the data needed to make sure the huge tank is structurally sound and that the repaired stringers can cope with the thermal stresses of fueling.

The tests also are designed to make sure the normal stresses and temperature extremes won't lead to potentially dangerous losses of foam insulation during Discovery's climb out of the dense lower atmosphere when debris poses the biggest threat to the ship's fragile heat shield.

Assuming the weather cooperates and the fueling test is carried out late this week, Discovery will be hauled back to the Vehicle Assembly Building next week to give engineers a chance to carry out non-destructive X-ray inspections of the backside of the huge tank, which cannot be done at the launch pad.

Some engineers have recommended adding additional doublers to other stringers where loads are most severe to provide additional strength, but it's not yet clear if that might be necessary.

In any case, strain gauges and temperature sensors installed as part of the tanking test will be removed and the tank's foam insulation will be repaired, operations that will be easier to carry out in the controlled environment of the VAB. Discovery will remain attached to the tank throughout the operation.

If the root cause of the cracks cannot be determined, the testing should provide the data needed to either justify making another launch attempt or to order additional tests and/or repairs.

The next shuttle launch window opens Feb. 3 and closes Feb. 10. Assuming a tanking test Friday, Discovery will be moved back to the VAB Dec. 21 or 22. If no problems are found in the wake of the fueling test, the inspections in the VAB and the testing underway at other NASA centers, and if Discovery is back at the launch pad by around Jan. 14, NASA should be able to make another launch attempt Feb. 3.

But if any significant problems or questions emerge from the testing and analysis, launch on a space station resupply mission, Discovery's 39th and final flight, could slip even further behind schedule.

NASA originally hoped to launch Discovery Nov. 1, but the flight was delayed one and then two days because of work to replace quick-disconnect fittings in the shuttle's right-side orbital maneuvering system rocket pod. Launch then was delayed 24 hours to Nov. 4 because of an electrical glitch in the circuitry associated with a main engine controller. Troubleshooting showed the likely cause was transient contamination in a cockpit circuit breaker.

A launch attempt Nov. 4 was called off before the start of fueling because of stormy weather at the Kennedy Space Center. The launch attempt on Nov. 5 was cancelled because of a gaseous hydrogen leak in a 7-inch vent line quick-disconnect fitting. Engineers then saw the cracked insulation on the side of the shuttle's external tank.

After the cracks were discovered, launch was delayed to no earlier than Nov. 30. Launch then slipped to no earlier than Dec. 3 and finally to NET Dec. 17. On Dec. 3, NASA managers said more time was needed to resolve the problem and launch was delayed to at least Feb. 3.

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CBS NEWS Coverage of Breaking Space News

02:50 PM 12/03/10 Update: Shuttle launch delayed to at least Feb. 3

By William HARWOOD
CBS News Space Consultant

Launch of the shuttle Discovery on a space station resupply mission will be delayed until at least Feb. 3, NASA managers announced Friday, to give engineers more time to carry out tests to help figure out what caused cracks in the ship's external tank and what, if any, modifications might be needed before the ship can be cleared for flight.

"It's time to pursue a different path, and that's to head out with some test data," Bill Gerstenmaier, chief of space operations at NASA headquarters, told reporters. "Basically what we're going to do with these tests is make sure we didn't overlook anything, we'll see if these tests can reveal any new information for us and it'll also help us sort out what the real problems are we need to be working on versus ones that we just think theoretically may be there."

Assuming the upcoming work gives NASA the confidence to proceed, a launch on Feb. 3 would be targeted for 1:34:28 a.m. EST, roughly the moment Earth's rotation carries launch pad 39A into the plane of the International Space Station's orbit. Landing back at the Kennedy Space Center would be expected the evening of Feb. 13.

If that schedule holds up, launch of the shuttle Endeavour on a mission to deliver a $2 billion physics experiment to the space station, which had been scheduled for Feb. 27, would slip to April 1 at 3:15:55 a.m. EDT. Launch of NASA's final planned shuttle mission, a station resupply flight with the shuttle Atlantis, would remain targeted for next summer.

But that schedule assumes engineers resolve major questions about the ability of Discovery's tank to withstand the rigors of fueling and launch.

Despite weeks of around-the-clock analysis, engineers have not been able to determine the root cause of four cracks in two adjacent structural ribs, or stringers, making up a compartment in the external tank that separates liquid oxygen and hydrogen tanks. The cracks were discovered after a Nov. 5 launch attempt was scrubbed because of a gaseous hydrogen leak where a vent line attaches to the side of the tank. That problem was traced to a quick-disconnect misalignment issue, repairs were made and NASA managers are confident the system will work properly the next time Discovery is fueled for launch.

Engineers also repaired the stringer cracks, splicing in replacement sections, attaching "doublers" to add strength and re-applying foam insulation. But figuring out what caused the cracks in the first place has turned out to be a major engineering challenge. Before Discovery can be cleared for launch, the community needs to understand the likelihood of new cracks forming that could lead to potentially dangerous foam debris during ascent or possibly even compromise the tank's structural integrity.

"We've hit a point where there is no obvious answer as to what occurred," said John Shannon, the shuttle program manager at the Johnson Space Center in Houston. "What that means is we have to take the next step, we have to look in greater detail to understand what types of stresses you could put in these stringers in the assembly process, see how they could line up to add stress to that stringer and we have to do that through a demonstration. Analysis is not going to get us there."

Repeating a well-known phrase attributed to Wernher von Braun, Shannon said "one good test is equal to a thousand expert opinions, right? So we're at the point where we need that test, we need that fine level of data to understand exactly how those assembly stresses could line up to give us a crack when we initially loaded."

The lightweight aluminum-lithium alloy used in shuttle external tanks is known to be more brittle than the heavier aluminum material used in earlier fuel tanks. Cracks in aluminum-lithium components are not unusual -- an average of one per tank is found and repaired during manufacturing -- but Discovery's are the first to be detected at the launch pad, the apparent result of thermal stresses.

External tank hardware contracts or shrinks slightly when exposed to ultra-low-temperature rocket fuel. The cracks in this case occurred near the top of the intertank where the stringers meet a flange that runs around the circumference of the lower section of the liquid oxygen tank. Thermal stresses tend to pull the tops of the stringers inward as the oxygen tank is chilled, but the hardware is designed to accommodate that.

Engineers suspect some sort of unexpected built-in load was present that, in combination with normal thermal stress, resulted in stress-relief fractures in two stringers when the tank was loaded with propellants Nov. 5. But the precise mechanism is unclear and as a result, engineers are unable to accurately model the tank's response to the forces it will experience during another fueling and, eventually, launch.

To get a better understanding of what might be going on, two major tests are planned. One team of engineers will build a high-fidelity mockup of the ribbed intertank components that cracked, including deliberate flaws. The idea is to replicate, if possible, the damage seen during the Nov. 5 fueling.

At the Kennedy Space Center, strain gauges and temperature sensors will be attached to Discovery's tank before a fueling test later this month to collect data on the actual thermal stresses experienced when liquid hydrogen and oxygen are pumped aboard. Along with the sensors, stereo cameras will be used to measure exactly how much the tank shrinks during fueling.

"We're hoping the optical piece, plus the strain gauge measurements, will give us a really great indication of what the stress level is in those stringers," Shannon said. "We believe the design is robust and should not fracture under that stress. We'll verify that and then we'll add the assembly issues you could potentially have to see if we can get to a root cause.

"We were hopeful early on that it would be some kind of very obvious kind of flaw. Didn't happen. Then we were hopeful that just a simple cryo tanking would cover us for any ascent loads. It's very close, but it's not quite there. So now we have to go to that next level ... to get the root cause and determine what our screening criteria is to fly that tank confidently."

The fueling test will mimic an actual launch countdown.

"I want to do a test in a flight configuration," Shannon said. "What that means is that we would remove foam, that nice foam they just put on the tank (for repairs), we would go remove that, we would put our instrumentation on there and then we're going to foam it back up. Because I want the most accurate models I could possibly get of the stress and the temperatures in that area in a flight configuration. That takes time. That's what's kind of driven us out of the December window."

NASA originally hoped to launch Discovery Nov. 1, but the flight was delayed one and then two days because of work to replace quick-disconnect fittings in the shuttle's right-side orbital maneuvering system rocket pod. Launch then was delayed 24 hours to Nov. 4 because of an electrical glitch in the circuitry associated with a main engine controller. Troubleshooting showed the likely cause was transient contamination in a cockpit circuit breaker.

A launch attempt Nov. 4 was called off before the start of fueling because of stormy weather at the Kennedy Space Center. The launch attempt on Nov. 5 was cancelled because of the gaseous hydrogen leak. After the cracks were discovered, launch was delayed to no earlier than Nov. 30. Launch then slipped to no earlier than Dec. 3 and finally to NET Dec. 17. It became obvious after a PRCB meeting Thursday that more time was needed to resolve the problem and launch was delayed to at least Feb. 3.

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CBS NEWS Coverage of Breaking Space News

5:50 PM 12/02/10 Update: 'Root cause' of shuttle tank cracks still not known; fueling test expected

By William HARWOOD
CBS News Space Consultant

NASA managers and engineers met Thursday to discuss the potential root cause of cracks in the shuttle Discovery's external tank, what additional tests might be needed and what, if any, modifications might be required before another launch attempt can be made.

Despite around-the-clock work to assess the problem, engineers still do not understand what caused cracks in structural ribs, or stringers, during fueling for a Nov. 5 launch attempt, a critical element in the development of an acceptable flight rationale, or engineering justification, for making another launch attempt.

"The one thing they don't have is root cause," said one NASA official. "They're just not there yet."

NASA is still holding open the possibility of a launch between Dec. 17 and 20. But the amount of work required to get there does not appear to fit in the available time. The schedule will be compressed even more by a decision late Thursday to carry out a fueling test to collect more data on how the tank's structural components respond to ultra-low temperatures.

It is not yet known when such a test could be carried out. In one option, sensors would be attached to the skin of the tank prior to fueling to precisely measure the stresses in the structure.

But installing such instrumentation and cabling at the launch pad, which would require cutting away more foam insulation, is a challenge in itself. Some engineers favor carrying out a fueling test without any additional sensors, loading the tank and pressurizing it for launch. Any cracks in the tank's foam insulation would be seen and X-ray analysis could find any cracks in the underlying metal.

Sources said Wednesday the requirements of an instrumented tanking test likely would rule out any attempt to launch this month. But they held open the possibility of a near-term launch if an un-instrumented test shows no problems and the on-going engineering analysis shows the tank has enough safety margin to withstand any credible failures.

During a four-hour program requirements control board meeting Thursday, engineers did not even get to a discussion of fueling test options or potential launch dates. The analysis will continue and in the meantime, the "no-earlier-than" Dec. 17 launch date placeholder is "still in play," an official said.

NASA originally hoped to launch Discovery on its 39th and final mission Nov. 1, but a series of technical problems caused repeated delays. After a gaseous hydrogen leak in an external tank vent arm derailed a launch attempt Nov. 5, engineers discovered cracks in two adjacent stringers making up the ribbed intertank compartment that separates the tank's liquid oxygen and hydrogen sections.

The vent line has since been repaired, but the crack issue has proven much more difficult to resolve. Engineers believe normal shrinkage due to ultra-low-temperature propellants, coupled with stresses built into the tank, caused the two stringers to crack near the top of the intertank.

What might have caused the presumed built-in stress, or pre load, is not yet known. But before Discovery can be cleared for another launch attempt, engineers must show the tank can withstand the rigors of fueling and launch without developing similar, or worse, cracks that could lead to the loss of foam insulation or compromise the structural integrity of the tank.

As of this writing, sources say the most likely scenario is an instrumented fueling test followed by a roll back to the Vehicle Assembly Building where platforms can be put in place to give engineers better access to the entire circumference of the intertank. Using sophisticated scanners, technicians then could closely inspect all of the stringers and their connections to other structural components to make sure no new cracks formed during exposure to low temperatures.

At the same time, structural braces called doublers are being prepared that could be attached to beef up any suspect or damaged stringers. But a roll back to the VAB would delay launch to the next window in February and NASA managers have not yet officially taken that step.

=================================

CBS NEWS Coverage of Breaking Space News

By William HARWOOD
CBS News Space Consultant

NASA managers reviewing the progress of repairs to the shuttle Discovery's external tank and the rationale for making another launch attempt decided Wednesday to pass up an early December launch window, delaying the flight to at least Dec. 17 and possibly all the way to February.

Shuttle Program Manager John Shannon told reporters engineers need more time to understand what caused cracks to develop in structural ribs, or stringers, during fueling Nov. 5 to better assess the likelihood of additional cracks during flight that could lead to potentially damaging foam insulation losses or even structural failure. While the latter is believed to be a remote possibility, engineers need to make sure. And that will take time.

"Clearly we're not ready for the December 3rd-through-7th window that's coming up," Shannon said. "We're going to leave the option open for the next launch window that starts Dec. 17. But a lot of data has to come together for us to support that. I don't think the team is worried about any specific launch date at all right now. They're just worried about getting the proper data so we can determine what our risk exposure is to this problem. Once we determine that and determine what the appropriate path forward is, then we'll go off and pick the right launch date."

A launch on Dec. 17 would occur at 8:51:53 p.m. EST (GMT-5). Docking with the space station would be expected around 5 p.m. on Dec. 19, followed by two spacewalks, one on Dec. 21 and the other on Dec. 23. Appropriately enough, the crew would enjoy a half day of off-duty time on Christmas Day, followed by undocking Dec. 26 and landing back at the Kennedy Space Center the afternoon of Dec. 28.

But Shannon cautioned that the Dec. 17 "no-earlier-than" date is little more than a planning target at this point, the first day a launch would be possible following a Russian Soyuz launch and docking Dec. 15 and 17 respectively. As it now stands, the shuttle could launch through Dec. 20 without any major impacts. Launches after that also are possible, but in those cases the shuttle would be in orbit during the New Year transition, requiring the ship's flight computers to be reconfigured. That would have to be done during a period of light activity, requiring close coordination with space station planners.

Even if the tank is cleared for launch by Dec. 17, mission managers may have to contend with reduced ascent performance because of the density of the winter atmosphere. Internal studies indicated cargo would have to be off loaded, but Bill Gerstenmaier, director of space operations at NASA headquarters, said Wednesday that was not the case.

In any case, if Discovery remains grounded through December, the flight would slip to February because of conflicts with other unmanned cargo launches and temperature constraints related to the station's orbit. The next official launch window opens Feb. 27 and closes March 6. But it may be possible to launch Discovery between Feb. 3 and 10 if a Japanese cargo ship, scheduled to arrive in late January, can be moved to another port on the space station.

A key element of the "flight rationale" discussion is an understanding of what caused cracks in the external tank stringers spotted after a Nov. 5 launch scrub and whether they represent a generic problem that poses a broader threat. While there are several theories, engineers have not yet identified the root cause.

Cracks became more common after the 1998 debut of new super lightweight tanks built with a more brittle aluminum-lithium alloy. Shannon said a review of manufacturing records showed that some 5,000 stringers were built for 43 aluminum-lithium tanks. Out of that total, 31 cracks were found that required repairs, including four in Discovery's tank and three in a tank scheduled for use by the shuttle Atlantis next summer.

But Discovery's cracks were the first to be discovered at the launch pad, the presumed result of exposure to ultra-low temperatures during fueling.

The problem was spotted after a gaseous hydrogen leak in a vent line attachment fitting forced a launch scrub Dec. 5. During de-tanking operations, engineers spotted a large crack in the foam insulation of the intertank flange area near the base of the upper liquid oxygen tank. When the insulation was cut away for repairs, four cracks in two underlying stringers were found.

Using a certified repair technique, the damaged stringer sections were cut out and replacements were spliced in, along with "doublers" to provide additional strength. Fresh BX foam then was sprayed on and shaped to blend in with the surrounding insulation.

Working in parallel, engineers also replaced the hydrogen vent line quick-disconnect fitting after tracing the leak to a misalignment issue. A suspect circuit breaker believed to be responsible for a subtle electrical problem that led to an earlier launch delay also was replaced.

But before Discovery can be cleared for launch, engineers must show that any additional cracks that might form in the tank stringers after the shuttle is re-fueled won't cause foam to pop off while the shuttle is climbing out of the dense lower atmosphere. During the first two minutes or so of flight, the density of the atmosphere is still high enough to quickly slow lightweight foam debris, allowing the rapidly accelerating shuttle to fly into it at a high relative velocity.

At a more fundamental level, the crack issue raises questions about the overall structural integrity of the tank and the ability of weakened stringers to handle the forces experienced during launch. The stringers are not considered load-bearing components, but engineers need to verify the tank's safety margins. Whether cracks in the aluminum-lithium ribs represent a generic problem remains to be seen.

"As we started looking at it, we have had a history on these stringers during assembly occasionally of getting cracks in them that are caused, we believe, by the assembly process," Shannon said. "If you look at the design -- and we've reviewed over the last week and a half very closely the design of these stringers, how they're assembled, how they're attached, the loads they would take in the initial cryo loading and also during launch -- they have plenty of design margin. So a properly assembled stringer in the expected flight environment will not crack."

But problems during assembly, including fastener misalignment or mishandling, could have caused a problem that escaped detection and later showed up under the thermal stresses of fueling.

"So the question was ... did we have an escape in our inspection methods that allowed a flaw to get into the assembly of the intertank that was exposed when we did our cryo loading? The other question was, did you have some kind of assembly misalignment that could have added additional stress to that piece that when you added the stress of cryo loading, you would overload that piece and you'd get this crack?

"The hope last week, and why we were kind of sequentially slipping launch dates, was that we would show that there was a flaw in this material, that you could go find some material defect that got through our process," he said. "And we also hoped the initial cryo loading stress on that part would be the maximum stress that that part saw during the entire flight phase. As we're going through the investigation, neither one of those points is as clear as we need it to be to commit to go fly."

However the discussion plays out, NASA's options are limited. The agency only plans three more missions: Discovery's, a flight by Endeavour at the end of February and a final flight by Atlantis next summer. There are no spare tanks and little time to make major changes without significant downstream impacts.

Even so, Shannon said his team will not be driven by schedule pressure and that Discovery will only be launched if the community agrees it is safe to do so.

"It's a complex problem," he said. "If you think about it, you're putting it through a very difficult environment where you have thermal stresses, you have bending stresses, you have tension and compression when you're lifting off. The team has done a great job so far modeling all of that and helping us understand where our vulnerabilities are in that stringer design. The main focus for the program right now is to understand the exposure.

"We need to understand our risk, what is the risk that something else could have gotten through our process and gotten out to the launch pad. There are a lot of things on the table. We could potentially instrument the vehicle and do another tanking test so that we would understand the stresses in that area even better and further improve our models to know what is our exposure to risk?

"We may end up deciding that we need to get some X-rays of the back side of the tank. That's not available to us on the launch pad so if we had to do that we'd roll the vehicle back to the VAB (Vehicle Assembly Building) and put the platforms around it and get that data.

"So we're going to develop the stress models and do all our testing and look at all of our assembly methods and pull together that whole story to understand what is our risk exposure here," he said. "If the we can't get enough data to show that our risk exposure is acceptable, then we're going to have to look at other options."

Those options might include additional work to strengthen the stringers or additional testing and inspections. Shannon would not rule out eventually switching to another tank, but he pointed out that the three in NASA's inventory were built the same way and with the same materials.

Another issue facing NASA planners is the health of the U.S. oxygen generation system aboard the International Space Station. The system currently is shut down and the crew is relying on a Russian generator and stored air pending the return to Earth of a critical component that failed earlier. While a spare component has been installed in the U.S. system, engineers do not want to restart the oxygen generator until they know what caused the original problem. In the meantime, NASA plans to deliver additional oxygen with Discovery.

Because of a variety of complex technical issues, the amount of oxygen Discovery can deliver to the station is directly related to when the shuttle takes off. And as far as the December opportunities, sooner is better than later.

But developing a flight rationale that is acceptable to the community could push the mission into February depending on how the analysis plays out.

=================================

CBS NEWS Coverage of Breaking Space News

By William HARWOOD
CBS News Space Consultant

NASA managers reviewing the progress of repairs to the shuttle Discovery's external tank and the rationale for making another launch attempt decided Wednesday to pass up an early December launch window, delaying the flight to at least Dec. 17 and possibly all the way to February, sources said.

A news conference with Bill Gerstenmaier, director of space operations at NASA headquarters, and John Shannon, the shuttle program manager at the Johnson Space Center, was scheduled for 3 p.m. EST to discuss Discovery's launch status.

In the meantime, sources said, the Dec. 17 "no-earlier-than" date is little more than a planning target at this point, the first day a launch would be possible following a Russian Soyuz launch and docking Dec. 15 and 17 respectively.

Even if the tank is cleared for launch by then, mission managers would have to remove several hundred pounds of cargo because of a variety of technical factors, including the density of the winter atmosphere and its effects on the shuttle's ascent performance. They also would have to buy into having a shuttle mission underway over the Christmas holidays.

If Discovery remains grounded through December, the flight would slip to February because of conflicts with other unmanned cargo launches and temperature constraints related to the station's orbit. The next official launch window opens Feb. 27. But it may be possible to launch Discovery in early February if a Japanese cargo ship, scheduled to arrive in late January, can be moved to another port on the space station.

A key element of the "flight rationale" discussion is an understanding of what caused cracks in vertical ribs, or stringers, spotted after a Nov. 5 launch scrub and whether they represent a generic problem that poses a broader threat. While there are several theories, engineers have not yet identified the root cause.

Cracks became more common after the 1998 debut of new super lightweight tanks built with a more brittle aluminum-lithium alloy. Since then, 29 cracks in stringers making up the ribbed "intertank" section that separates liquid hydrogen and oxygen tanks have been found and repaired in 18 external tanks, including Discovery's and a tank scheduled for use by the shuttle Atlantis next summer.

The problem with Discovery's tank was spotted after a gaseous hydrogen leak in a vent line attachment fitting forced a launch scrub Dec. 5. During de-tanking operations, engineers spotted a large crack in the foam insulation of the intertank flange area near the base of the upper liquid oxygen tank. When the insulation was cut away for repairs, four cracks in two underlying stringers were found.

Using a known repair technique, the damaged stringer sections were cut out and replacements were spliced in, along with "doublers" to provide additional strength. Fresh BX foam then was sprayed on and shaped to blend in with the surrounding insulation.

Working in parallel, engineers also replaced the hydrogen vent line quick-disconnect fitting after tracing the leak to a misalignment issue. A suspect circuit breaker believed to be responsible for a subtle electrical problem that led to an earlier launch delay also was replaced.

But before Discovery can be cleared for launch, engineers must show that any additional cracks that might form in the tank stringers after the shuttle is re-fueled won't cause foam to pop off while the shuttle is climbing out of the dense lower atmosphere. During the first two minutes or so of flight, the density of the atmosphere is still high enough to quickly slow lightweight foam debris, allowing the rapidly accelerating shuttle to fly into it at a high relative velocity.

At a more fundamental level, the crack issue raises questions about the overall structural integrity of the tank and the ability of weakened stringers to handle the forces experienced during launch. The stringers are not considered load-bearing components, but engineers need to verify the tank's safety margins. Whether cracks in the aluminum-lithium ribs represent a generic problem remains to be seen. It is possible, engineers say, that shuttles have been flying with undetected cracks for years.

"The immediate reaction is, have we been getting these all along on super lightweight tanks? And the answer's 'probably,' depending on what's causing it," a NASA engineer who asked not to be named said Tuesday. "And the fact that they found more cracks on this tank does suggest that it's a generic flaw. But if it really is superficial cracks that don't affect the stiffness, don't affect load-carrying capability, then it really doesn't matter."

However the discussion plays out, NASA's options are limited. The agency only plans three more missions: Discovery's, a flight by Endeavour at the end of February and a final flight by Atlantis next summer. There are no spare tanks and little time to make major changes.

Even so, shuttle managers have repeatedly said they will not be driven by schedule pressure and that Discovery will only be launched if the community agrees it is safe to do so.

"They're doing a very, very good, honest job of pulling the data in," the NASA engineer said.

The year's final shuttle launch window opens Nov. 29 and closes Dec. 6, the last day Discovery could take off and finish its space station resupply mission before the planned docking of a Russian Soyuz capsule Dec. 17 carrying three fresh crew members. NASA managers announced last week that tank repairs and inspections would delay another attempt to launch Discovery until at least Dec. 3.

With the Dec. 3-6 launch window now off the table, planners are looking into the possibility of launching Discovery after the Soyuz docking, resulting a fight over the Christmas holidays.

One major issue facing NASA planners is the health of the U.S. oxygen generation system aboard the International Space Station. The system currently is shut down and the crew is relying on a Russian generator and stored air pending the return to Earth of a critical component that failed earlier. While a spare component has been installed in the U.S. system, engineers do not want to restart the oxygen generator until they know what caused the original problem. In the meantime, NASA plans to deliver additional oxygen with Discovery.

Because of a variety of complex technical issues, the amount of oxygen Discovery can deliver to the station is directly related to when the shuttle takes off. And as far as the December opportunities, sooner is better than later.

But developing a flight rationale that is acceptable to the community could push the mission into February depending on how the analysis plays out.

=================================

CBS NEWS Coverage of Breaking Space News

08:45 AM, 11/24/10 Update: Shuttle managers, engineers meet Wednesday to discuss tank repairs, 'flight rationale'

By William HARWOOD
CBS News Space Consultant

(Editor's Note: This posting was delayed by a server problem)

NASA and contractor managers and engineers gathered Wednesday to review the status of repairs to fix cracks and damaged foam insulation on the shuttle Discovery's external tank and to discuss an ongoing engineering review before deciding whether the ship can be safely launched as early as Dec. 3.

A key element of the "flight rationale" discussion is an understanding of what caused cracks in vertical ribs, or stringers, spotted after a Nov. 5 launch scrub and whether they represent a generic problem that poses a broader threat. While there are several theories, engineers have not yet revealed any conclusions about the root cause.

But cracks became more common after the 1998 debut of new super lightweight tanks built with a more brittle aluminum-lithium alloy. Since then, 29 cracks in stringers making up the ribbed "intertank" section that separates liquid hydrogen and oxygen tanks have been found and repaired in 18 external tanks, including Discovery's and a tank scheduled for use by the shuttle Atlantis next summer.

If the shuttle is cleared for launch Dec. 3, at 2:52:01 a.m. EST (GMT-5), the countdown would begin at 1 a.m. on Nov. 30. Discovery's crew -- commander Steven Lindsey, pilot Eric Boe, Nicole Stott, Michael Barratt and spacewalkers Timothy Kopra and Alvin Drew -- would fly back to the Kennedy Space Center early Monday for final preparations.

But it is not yet clear if any final decisions will be made at the program requirements control board meeting today or if NASA will defer a formal go/no-go decision until after a planned management review Monday.

The problem with Discovery's tank was spotted after a gaseous hydrogen leak in a vent line attachment fitting forced a launch scrub Dec. 5. During de-tanking operations, engineers spotted a large crack in the foam insulation of the intertank flange area near the base of the upper liquid oxygen tank. When the insulation was cut away for repairs, four cracks in two underlying stringers were found.

Using a known repair technique, the damaged stringer sections were cut out and replacements were spliced in, along with "doublers" to provide additional strength. Fresh BX foam then was sprayed on and shaped to blend in with the surrounding insulation.

Working in parallel, engineers also replaced the hydrogen vent line quick-disconnect fitting after tracing the leak to a misalignment issue. A suspect circuit breaker believed to be responsible for a subtle electrical problem that led to an earlier launch delay also was replaced.

But before Discovery can be cleared for launch, engineers must show that any additional cracks that might form in the tank stringers after the shuttle is re-fueled won't cause foam to pop off while the shuttle is climbing out of the dense lower atmosphere. During the first two minutes or so of flight, the density of the atmosphere is still high enough to quickly slow lightweight foam debris, allowing the rapidly accelerating shuttle to fly into it at a high relative velocity.

At a more fundamental level, the crack issue raises questions about the overall structural integrity of the tank and the ability of weakened stringers to handle the forces experienced during launch. The stringers are not considered load-bearing components, but engineers need to verify the tank's safety margins. Whether cracks in the aluminum-lithium ribs represent a generic problem remains to be seen. It is possible, engineers say, that shuttles have been flying with undetected cracks for years.

"The immediate reaction is, have we been getting these all along on super lightweight tanks? And the answer's 'probably,' depending on what's causing it," said a NASA engineer who asked not to be named. "And the fact that they found more cracks on this tank does suggest that it's a generic flaw. But if it really is superficial cracks that don't affect the stiffness, don't affect load-carrying capability, then it really doesn't matter."

However the discussion plays out, NASA's options are limited. The agency only plans three more missions: Discovery's, a flight by Endeavour at the end of February and a final flight by Atlantis next summer. There are no spare tanks and little time to make major changes.

Even so, shuttle managers have repeatedly said they will not be driven by schedule pressure and that Discovery will only be launched if the community agrees it is safe to do so.

"They're doing a very, very good, honest job of pulling the data in," the NASA engineer said.

The year's final shuttle launch window opens Nov. 29 and closes Dec. 6, the last day Discovery can take off and finish its space station resupply mission before the planned docking of a Russian Soyuz capsule Nov. 17 carrying three fresh crew members. NASA managers announced last week that tank repairs and inspections would delay another attempt to launch Discovery until at least Dec. 3.

Shuttle planners have looked into the possibility of launching Discovery after the Soyuz docking, resulting a fight over the Christmas holidays. But no decisions have been made.

One major issue facing NASA planners is the health of the U.S. oxygen generation system aboard the International Space Station. The system currently is shut down and the crew is relying on a Russian generator and stored air pending the return to Earth of a critical component that failed earlier. While a spare component has been installed in the U.S. system, engineers do not want to restart the oxygen generator until they know what caused the original problem. In the meantime, NASA plans to deliver additional oxygen with Discovery.

Because of a variety of complex technical issues, the amount of oxygen Discovery can deliver to the station is directly related to when the shuttle takes off. And as far as the December opportunities, sooner is better than later.

But developing a flight rationale that is acceptable to the community could push the mission into February if more analysis or repairs are required, likely delaying Endeavour's flight to April.

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CBS NEWS Coverage of Breaking Space News

03:25 PM, 11/17/10 Update: Tank repairs proceed amid work to develop 'flight rationale'

By William HARWOOD
CBS News Space Consultant

Engineers are pressing ahead with work to repair small cracks in the shuttle Discovery's external tank and to finish installation and tests of a replacement hydrogen vent line quick-disconnect fitting that grounded the ship Nov. 5. At the same time, troubleshooters are assessing the structural integrity of the tank and its foam insulation to develop the necessary flight rationale, or justification, for proceeding with another launch as early as Nov. 30.

Bill Gerstenmaier, associate administrator for space operations at NASA headquarters, and John Shannon, the shuttle program manager at the Johnson Space Center in Houston, plan to brief reporters Monday after assessing the status of repairs and an engineering analysis of the tank's ability to withstand the normal loads, or forces, experienced during fueling, launch and the climb to space.

One concern is the potential for foam insulation to break away from the repaired area of the cracks, or similar areas, that could hit the shuttle's heat shield during the early stages of ascent when impact damage can be most severe. Other issues include proving that any fresh cracks that might form when the tank is loaded with supercold propellants are seen before launch and if they are not, that they will not grow or compromise the structural integrity of the tank during ascent.

Given the time available, developing flight rationale could be a challenge. The next shuttle launch window opens Nov. 30 and closes Dec. 6. NASA managers are examining other options that might be available later in the month, sources say. But if those don't pan out, and if Discovery misses the upcoming window, the fight would be delayed to late February.

Despite the appearance, at least, of schedule pressure and the recurring problem of tank cracks -- some 38 stringer cracks have been seen in 20 tanks since switching to a lightweight aluminum-lithium alloy -- Shannon has told the shuttle team that NASA will not be driven by the schedule and that Discovery will not be cleared for launch without a solid flight rationale.

In any case, engineers at launch pad 39A have replaced the 7-inch gaseous hydrogen vent line quick-disconnect fitting and mounting plate on the side of Discovery's tank that leaked during fueling Nov. 5, scrubbing the ship's fourth launch attempt.

During the final hours of a shuttle countdown, a small amount of liquid hydrogen rocket fuel turns into a gas inside the ship's external tank. To maintain the proper pressure in the tank, a valve is periodically cycled to vent the gas overboard to a nearby "flare stack" where it is burned. During Discovery's fueling, sensors detected a major gaseous hydrogen leak at the vent line attachment fitting and launch was called off.

The quick-disconnect fitting and the ground umbilical carrier plate, or GUCP, that helps attach it to the side of the tank were removed and subjected to a detailed inspection. Engineers quickly discovered that the quick-disconnect hardware was not as precisely centered as required, a lack of concentricity that is believed to have allowed a leak path to develop when the hardware was exposed to ultra-low temperatures.

Replacement hardware has been installed that is as concentric as possible with the available components. Engineers are hopeful leak tests at higher-than-normal pressures will confirm a tight seal. NASA managers have not yet decided whether to order an actual fueling test to confirm leak-free performance under cryogenic conditions. But the engineering community is confident, officials say, that the carefully aligned hardware will work properly.

Meanwhile, another team of engineers and technicians is repairing the cracks that were discovered after the Nov. 5 launch attempt was called off. After removing damaged foam insulation, cracks were found in two adjacent structural braces, or stringers, making up the ribbed intertank section between the external tank's hydrogen and oxygen sections. The damage was seen just below the top flange of the intertank where it joins with the tank's upper liquid oxygen section.

The repair plan called for engineers to cut out the damaged stringer sections. Replacement sections will be riveted into place by this weekend, along with so-called doublers to provide additional strength. Fresh foam insulation then will be sprayed on and shaped to blend in with surrounding insulation. That work should be complete by Monday, followed by a four-day "cure."

Engineers also are evaluating techniques that can be used to look for signs of additional cracks under the foam insulation around the perimeter of the upper intertank flange on the side of the tank facing the shuttle. No foam loss from the flange area has ever been recorded, providing at least some additional confidence that cracks in this area are not a frequent or widespread phenomenon.

To make the opening of the shuttle's next launch window Nov. 30, Discovery's countdown must begin on Nov. 27. But it's not yet clear whether a fueling test will be required to test the vent line hardware, to make sure thermal stresses don't trigger more foam problems, or both.

A tanking test and subsequent foam inspection would add additional confidence in the failure analysis and repair work, officials say, but no final decisions have been made. As for the timing of such a test, it could be added to the countdown or carried out as a stand-alone operation. How that might play into the shuttle's eventual launch date remains to be seen.

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CBS NEWS Coverage of Breaking Space News

12:25 PM, 11/15/10 Update: Fourth crack found in shuttle tank

By William HARWOOD
CBS News Space Consultant

Engineers inspecting the shuttle Discovery's external tank have found a fourth crack in the structural ribs, or stringers, making up the outer skin of the compartment between the liquid oxygen and hydrogen sections.

Analysts are discussing techniques for making sure even more cracks are not present under the tank's foam insulation while work to repair the initial cracks proceeds.

Discovery was grounded Nov. 5 when sensors detected a gaseous hydrogen leak in a 7-inch vent arm quick-disconnect fitting attached to the side of the external tank. Launch was delayed until at least Nov. 30, the opening of the year's final shuttle launch window.

But the hydrogen leak was not the only problem for Discovery. Engineers later noticed a large crack in the foam insulation at the top of the external tank's ribbed intertank section.

When the foam around the crack was cut away, engineers found two 9-inch cracks in the flat attachment plates on either side of an underlying stringer known as S-7-2. NASA managers then decided to cut away additional foam and a third crack was found Friday on the stringer to the immediate left of the one that was initially discovered.

Over the weekend, a fourth crack was found in the left-side stringer, known as S-6-2, officials confirmed Monday. No cracks were found in stringers on the right side.

To fix the initial cracks, engineers decided to cut out the damaged section and to bolt in a replacement, along with an additional brace called a doubler to provide more strength. Presumably, the same repair can be used to fix the second stringer.

External tank crack repairs are not unusual. Some 29 stringer cracks were found in 18 previous tanks, according to an official familiar with their history. Four have now been found in Discovery's tank, ET-137, and three were found in a tank scheduled for use by the shuttle Atlantis next summer, ET-138. Doublers were used in 23 repairs.

Engineers suspect the use of a lightweight aluminum-lithium alloy in the tanks may be contributing to the crack problem.

While crack repairs are not unusual, the cracks in Discovery's tank are the first to be found at the launch pad, where access is more difficult. An environmental enclosure has been erected around the known damage site to facilitate repairs and the eventual application of fresh foam insulation.

It's not yet known whether more defects remain to be discovered, but engineers are optimistic high-tech instruments capable of detecting damage beneath the foam can be used to find any additional problems.

In the meantime, a different team of troubleshooters may have discovered what caused the gaseous hydrogen leak that scrubbed Discovery's Nov. 5 launch attempt. A careful inspection of the quick-disconnect hardware shows two areas where the hardware was not sufficiently concentric, or aligned, creating a possible leak path under cryogenic conditions.

A replacement ground umbilical carrier plate, or GUCP, has been installed on the tank and measurements show its alignment is near perfect. Engineers are assessing how to orient the quick-disconnect hardware in the carrier plate to ensure a tight fit.

NASA managers have not yet made an official decision on whether to order a tanking test, pumping liquid hydrogen back aboard, to make sure the replacement hardware is leak free. If the test is ordered, it likely will be carried out during an extended launch countdown, assuming the foam repairs can be completed in time.

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CBS NEWS Coverage of Breaking Space News

By William HARWOOD
CBS News Space Consultant

Engineers removed additional foam insulation near a cracked structural support strip, or stringer, in the shuttle Discovery's external tank and found yet another crack in an adjacent stringer, NASA officials confirmed late Friday.

Discovery was grounded Nov. 5 by a gaseous hydrogen leak in a 7-inch vent line quick-disconnect fitting, delaying the flight until at least Nov. 30 when the next available launch window opens.

Engineers later discovered an area of cracked foam insulation on the external tank in a ribbed section that separates the liquid oxygen and hydrogen tanks. When the damaged foam was cut away, two nine-inch-long cracks were found in an underlying attachment plate holding a vertical support strip, or stringer, in place.

Engineers quickly developed a plan to repair the damage by installing a replacement section, bolting on a so-called doubler to provide additional strength and then spraying on fresh insulating foam.

But first, additional foam was removed from the area to make sure no other problems were present. And that's when engineers discovered a small crack in the stringer to the immediate left of the one already known to be damaged.

"During foam removal and inspection of adjacent stringers to the one with two nine-inch cracks, technicians today identified an approximately three-inch crack on the left-hand adjacent stringer," NASA said on its shuttle web page. "This was not an unexpected result since the load was most likely transferred to the adjacent stringer when both sides of the original stringer cracked during tanking operations for Discovery’s scrubbed launch attempt on Nov. 5."

Engineers will use "structural math models" to characterize the forces acting on the stringers during launch to make sure repairs will be sufficient to provide the required margin of safety.

In the meantime, another team of engineers is finalizing plans for replacing the leaking hydrogen vent line fitting. They originally planned to install replacement hardware Friday, but managers have delayed the operation to early next week to collect additional data.

The goal is to measure and inspect additional ground umbilical carrier plate, or GUCP, components to make sure hardware is identified that will provide the best possible fit. The fitting that leaked apparently had an internal concentricity, or alignment problem that may have provided a leak path under cryogenic conditions.

NASA managers are considering a fueling test to make sure the replacement hardware remains leak-free when supercold propellants are pumped aboard. But given the foam repair work, managers have not yet settled on a target date for the test.

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CBS NEWS Coverage of Breaking Space News

By William HARWOOD
CBS News Space Consultant

A leaking hydrogen vent line attachment fitting on the side of the shuttle Discovery's external tank was removed and disassembled overnight, revealing an unevenly compressed internal seal, engineers reported. The quick-disconnect hardware also may have a less concentric fit than pre-fueling measurements indicated. An analysis is underway to determine if the defects are responsible for the gaseous hydrogen leak that grounded Discovery last Friday.

A replacement ground umbilical carrier plate, or GUCP, was previously fit-checked on Discovery's tank during its assembly and measurements indicated a better fit. Engineers plan to carry out a detailed comparison of the two mounting plates before deciding how to proceed.

But barring any other surprises, they likely will be cleared to install the replacement GUCP on Discovery's tank. A meeting is scheduled for Friday to discuss an expected fueling test to make sure the vent line is leak free under cryogenic conditions.

In the meantime, another team of engineers is refining plans for repairing a structural brace on the side of the tank that experienced two cracks during Discovery's fueling Friday. The defects were found after engineers cut away cracked foam insulation covering a vertical stringer, part of the ribbed structure of the compartment that separates the liquid hydrogen and oxygen tanks.

Based on past experience with a similar crack on external tank 138, scheduled for use by the shuttle Atlantis next summer, engineers believe they can repair Discovery's tank, ET-137, by attaching a so-called doubler on a replacement section of bracing. Fresh foam insulation can then be applied and shaped to fit.

In a statement posted on NASA's web site Thursday, the agency said the cracks may be the result of using a lightweight aluminum-lithium alloy in the latest generation of external tanks.

"While the material is stronger and lighter in weight, it is more brittle and has resulted in increased cases of cracked stringers in the areas noted," the statement said. "The cracked stringer section matches well with the area of foam that cracked, which indicates the stringer crack was the root cause of the foam crack.

"Analysis shows the intertank has sufficient structural capability for the launch and ascent environments with the cracks in a single stringer," the statement said. "Although the foam was firmly attached to the damaged structure, it is undesirable to launch in this configuration. This area is clearly visible during the pre-launch inspections and would have been detected by the final inspection team."

To fix the cracks, engineers likely will cut out the damaged section of the stringer and replace it with another piece that exactly matches the removed section. The doubler then will be attached to add additional strength followed by an application of BX foam. The insulation will require four days to cure.

"Exact schedules and repair options still are being evaluated," NASA said. "Engineers will meet Friday to discuss the status of the three repair activities underway, the external tank stringer and foam repair, the ground umbilical carrier plate and the cockpit panel L4 removal and replacement."

The latter is a circuit breaker panel in Discovery's cockpit that may be responsible for a subtle electrical glitch blamed for an earlier launch delay last week. While the system appears sound, NASA managers decided to replace the panel while the other repair work is underway.

The engineering community is hopeful the repair work can be completed before the opening of the year's final shuttle launch window Nov. 30.

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CBS NEWS Coverage of Breaking Space News

09:25 AM 11/11/10 Update: Leaking vent line attachment disassembled, apparent seal problem found

By William HARWOOD
CBS News Space Consultant

A leaking hydrogen vent line attachment fitting on the side of the shuttle Discovery's external tank was removed and disassembled overnight, revealing an unevenly compressed internal seal. The quick-disconnect hardware also may have a less concentric fit than pre-fueling measurements indicated. An analysis is underway to determine if the defects are responsible for the gaseous hydrogen leak that grounded Discovery last Friday.

A replacement ground umbilical carrier plate, or GUCP, was previously fit-checked on Discovery's tank during its assembly and measurements indicated a better fit. Engineers plan to carry out a detailed comparison of the two mounting plates before deciding how to proceed.

But barring any other surprises, they likely will be cleared to install the replacement GUCP on Discovery's tank. A meeting is scheduled for Friday to discuss an expected fueling test to make sure the vent line is leak free under cryogenic conditions.

In the meantime, another team of engineers is refining plans for repairing a structural brace on the side of the tank that experienced two cracks during Discovery's fueling Friday. The defects were found after engineers cut away cracked foam insulation covering a vertical stringer, part of the ribbed structure of the compartment that separates the liquid hydrogen and oxygen tanks.

Based on past experience with a similar crack on external tank 138, scheduled for use by the shuttle Atlantis next summer, engineers believe they can repair Discovery's tank, ET-137, by attaching so-called doublers on both sides of a replacement section of bracing. Fresh foam insulation can then be spayed on and sanded to fit.

The engineering community is hopeful the repair work can be completed before the opening of the year's final shuttle launch window Nov. 30.

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CBS NEWS Coverage of Breaking Space News

3:20 PM 11/10 Update: Underlying crack found in shuttle tank; repair options assessed

By William HARWOOD
CBS News Space Consultant

Cracked foam insulation on the shuttle Discovery's external tank was cut away overnight, revealing a serpentine crack in an underlying structural rib, or stringer. Based on experience repairing similar cracks on other tanks, sources said, engineers believe the damage can be fixed at the pad before the next launch window opens at the end of the month.

Working in parallel, another team of engineers is continuing work to disassemble a leaking hydrogen vent line quick-disconnect fitting that delayed Discovery's planned launching last Friday. Replacement hardware is expected to be installed by the end of the week, but it's not clear when testing and analysis to pin down the cause of last week's leak will be complete.

In any case, NASA managers are expected to order a tanking test to make sure the new hardware is leak free before moving forward with another countdown, sources said. And that assumes the crack repair work goes well. To minimize the impact of a fueling test on other pad operations, only liquid hydrogen would be loaded into the external tank's lower section to confirm the replacement vent line attachment is working properly.

Taking advantage of the launch delay, engineers also plan to replace a circuit breaker panel in Discovery's cockpit that may have played a role in a subtle electrical glitch that triggered a delay earlier last week. Panel L4, equipped with 18 replacement breakers, is expected to be re-installed in the cockpit by early next week.

The crack in the external tank's insulation occurred just after 7 a.m. EDT Friday, about an hour into the fueling procedure and shortly before the hydrogen leak was detected. The crack, located near the top of the ribbed intertank section that separates ET-137's liquid oxygen and hydrogen tanks, is similar to a backward question mark, measuring 46 inches from end to end.

Overnight, engineers at pad 39A cut away the foam insulation in the area of the crack, revealing an underlying crack in a structural stringer that is part of the vertical ribbing that makes up the intertank section. The crack appears to run in a wavy line from bolt to bolt in the stringer.

It is not yet clear what caused the underlying crack. It presumably could have been triggered by temperature-induced stress as the tank was loaded with supercold liquid oxygen and hydrogen rocket fuel. But a similar crack was found in ET-138, scheduled for use by the shuttle Atlantis next summer, and that tank has not yet been subjected to cryogenic temperatures. The cracks may be related to the use of lightweight materials in the latest generation of tanks.

The crack in Atlantis' tank was repaired and engineers likely will follow a similar approach with Discovery's tank, possibly installing so-called doublers to reinforce the damaged stringer or a replacement section. Assuming management clearance to proceed and no other problems, fresh foam will be sprayed on, cured and sanded to match the surrounding insulation.

The year's final shuttle launch window opens Nov. 30 and closes Dec. 5 or 6. If Discovery is not off the pad by then, the flight will slip to the end of February because of conflicts with other space station missions; a prohibition against flying over New Year's to avoid possible year-end rollover issues with the shuttle's software; and because of temperature constraints related to the space station's orbit.

Whether Discovery's launch team can complete the leak repair and fix the crack damage in time for a Nov. 30 liftoff is not yet known, but engineers are cautiously optimistic. The schedule is considered "success oriented," however, and there is little margin for error.

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CBS NEWS Coverage of Breaking Space News

4:15 PM 11/09/10 Update: Shuttle vent line, quick-disconnect inspections begin

By William HARWOOD
CBS News Space Consultant

Engineers worked to disconnect a 7-inch hydrogen vent line from a leaky quick-disconnect fitting on the side of the shuttle Discovery's external tank Tuesday that grounded the ship last Friday. Disassembly of the suspect fitting was expected overnight, with troubleshooters taking in situ photographs of the hardware, double-checking its alignment and looking for any obvious signs of trouble.

A detailed laboratory analysis of the quick-disconnect components is planned, but the fitting will not be re-attached. Instead, engineers plan to install replacement hardware by the end of the week that has a leak-free performance history.

Discovery's space station resupply flight is on hold until at least Nov. 30, the opening of the year's final shuttle launch window, while engineers work to resolve the leak, repair a large crack in the external tank's foam insulation and replace a circuit breaker that may have contributed to a subtle electrical glitch earlier last week.

Engineers also may carry out a fueling test, pumping supercold rocket fuel into Discovery's tank to make sure the replacement hardware is leak free, before pressing ahead with another round of launch preparations. But no final decisions have been made.

In any case, engineers say the foam crack may be the more significant challenge facing the launch team. It is not yet clear whether the damage is limited to the foam or whether the visible crack was caused by a defect of some sort in an underlying structural component. Repair plans are being developed to cover both scenarios.

Past leaks in the ground umbilical carrier plate, or GUCP, that connects a 7-inch hydrogen vent line to the side of the shuttle's external tank were blamed on temperature-induced trouble with internal seals, mechanical alignment of the hardware or both.

Extensive corrective actions were taken in the wake of two mission delays in 2009 and the system worked normally until Discovery's fueling Friday, a period covering 12 successful fuelings with six different tanks.

The vent line is used to carry excess hydrogen gas away from the shuttle as the tank is filled with super-cold propellant. During fueling, a valve is opened periodically to route hydrogen to the vent line as required to maintain the proper pressure in the tank. The excess gas is carried to a nearby "flare stack" where it is burned off. Just before launch, the vent valve is closed and the tank is pressurized for flight.

The vent line attaches to a port on the side of the external tank. At launch, an explosive charge fires, the quick-disconnect fitting separates and counterweights quickly pull the vent line down and out of the way.

During Discovery's fueling, sensors near the GUCP detected a major hydrogen leak about an hour after the three-hour tanking procedure began, well before the point where the earlier leaks showed up. Free hydrogen concentrations were above 6 percent, the limit of the sensors' ability to record, and the countdown was called off.

The vent line attachment fitting met specifications and passed pre-fueling tests, using helium at room temperature as a stand in for gaseous hydrogen. Because of the size of the leak, some engineers believe they will see an obvious defect when the hardware is taken apart and examined. Others are not so sure.

In parallel with the GUCP repair work, engineers are developing plans to repair a long crack that developed in the external tank's foam insulation during the fueling procedure Friday. Engineers planned to begin "dissecting" the damaged area overnight Tuesday or Wednesday, carefully cutting away the foam in the vicinity of the crack to expose underlying stringers and connecting panels.

If the underlying structure is sound, engineers likely will be cleared to spray on and shape new insulation to fill in the damage site. If temperature-induced stress or some other factor damaged the underlying structure, additional work could be required.

Repair crews also plan to remove circuit breaker panel L4 in the shuttle's cockpit Friday to troubleshoot a subtle electrical glitch that was blamed for one of Discovery's earlier launch delays last week. While "transient contamination" in one specific breaker may explain the problem, all 18 breakers in panel L4 will be replaced.

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CBS NEWS Coverage of Breaking Space News

3:55 PM 11/08/10 Update: Engineers gear up for shuttle troubleshooting

By William HARWOOD
CBS News Space Consultant

Engineers extended a launch pad access platform Monday in preparation for inspections and disassembly of a 7-inch hydrogen vent line quick-disconnect fitting to find out what caused a potentially dangerous leak that forced NASA to cancel the shuttle Discovery's planned launching last Friday.

Initial troubleshooting is expected to begin Tuesday. While it is not yet clear what might be needed to fix the problem, engineers may carry out a fueling test, exposing the vent line hardware to cryogenic conditions, before another launch attempt is made. In the meantime, the flight is on hold until at least Nov. 30.

In parallel with the vent line investigation, shuttle managers also are refining plans for repairing cracked foam insulation on Discovery's external tank that was discovered after Friday's launch scrub was declared.

The cracks are believed to have formed shortly after 7 a.m. EDT Friday, about an hour after engineers begin pumping supercold liquid oxygen and hydrogen rocket fuel into the huge tank and just before the vent line leak was detected. The longest single crack measures almost four feet long, end to end, in an area measuring about 10 inches by 20 inches.

Access at the pad is difficult, but technicians tentatively plan to begin cutting away foam in the damaged area Wednesday, using non-destructive evaluation to look for signs of any problems with the underlying metal might explain the cracking. A repair plan will not be approved until after the foam in the damaged area has been "dissected" and engineers get a better idea of what caused the problem in the first place.

Foam repairs are not unusual, but they are normally carried out in a controlled environment inside the cavernous Vehicle Assembly Building. At the pad, protective covers will be needed to control humidity and temperature before any foam spraying and shaping can be attempted.

Discovery's launch on an 11-day space station resupply mission, the orbiter's 39th and final flight, originally was planned for Monday, Nov. 1. But it was delayed two days to replace suspect quick-disconnect fittings in the pressurization system of the shuttle's right-side orbital maneuvering system rocket pod.

A launch attempt last Wednesday was called off because of a subtle electrical issue and bad weather prompted NASA managers to call off an attempt last Thursday.

Launch now is on hold until at least Nov. 30, the opening of the year's final shuttle launch window. Taking advantage of the delay, engineers also plan to replace a suspect circuit breaker in the shuttle's cockpit that may be responsible for the electrical irregularity observed last week.

The vent line is used to carry excess hydrogen gas away from the shuttle as the tank is filled with super-cold propellant. During fueling, a valve is opened periodically to route hydrogen to the vent line as required to maintain the proper pressure in the tank. The excess gas is carried to a nearby "flare stack" where it is burned off. Just before launch, the vent valve is closed and the tank is pressurized for flight.

The vent line attaches to a port on the side of the external tank with a complex quick-disconnect fitting known as a ground umbilical carrier plate, or GUCP. At launch, an explosive charge fires, the quick-disconnect fitting separates and counterweights quickly pull the vent line down and out of the way.

The vent line attachment fitting on the left side of Discovery's external tank met specifications and passed pre-fueling tests, using helium at room temperature as a stand in for gaseous hydrogen. But during fueling Friday, sensors indicated a massive leak near the quick-disconnect fitting, presumably the result of temperature-induced effects on the hardware.

Engineers later said the leak rate was the highest ever seen in that area.

Because of the size of the leak -- well above the 6 percent concentration that is the maximum level read by launch pad sensors -- engineers are hopeful some sort of obvious defect will be apparent when the hardware is disassembled and inspected. But others are not so optimistic.

While the vent line fitting in question met specifications, a key component was slightly more out of round than usual. Whether that can explain the problem or not remains to be seen, but the fitting met stringent alignment specifications before fueling and passed all of its normal leak checks.

Problems with hydrogen leakage in the GUCP delayed two shuttle missions in 2009. In the most recent previous leak, the shuttle Endeavour was grounded June 13 and 17, 2009, when sensors near the umbilical attachment plate detected hydrogen concentrations of more than 6 percent.

After the second launch scrub, engineers collected detailed measurements and concluded the problem was caused by an alignment issue between the hydrogen vent port on the tank and the vent line interface. To ensure a tight fit, engineers replaced a rigid Teflon seal with a more flexible design, modified the umbilical plate mounting pins and installed washer-like shims to counteract the alignment issue.

The shims provided additional pressure on one side of the attachment fitting that was believed to be pulling away slightly as the hardware contracted under cryogenic conditions.

The fix worked, Endeavour was safely launched in July 2009. No other GUCP problems occurred before Discovery's fueling Friday.

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CBS NEWS Coverage of Breaking Space News

3:25 PM 11/05/10 Update: Engineers hopeful Discovery leak, foam damage can be fixed in time for 11/30 launch try

By William HARWOOD
CBS News Space Consultant

After three launch delays due to technical problems and bad weather, the shuttle Discovery was grounded again Friday, its final launch delayed to at least Nov. 30, because of a hydrogen leak in a vent line attached to the ship's external tank.

After the scrub was declared, engineers discovered a large crack in the protective foam insulation on the tank that likely would have caused a launch delay even if the leak had not developed. Engineers have not yet evaluated the crack to know what sort of repairs, if any, might be needed or even whether the damage can be fixed at the launch pad.

But engineers are hopeful the problems can be resolved by the end of the month for another launch attempt at 4:05:46 a.m. EST.

"We will come back in late November and give it another shot," said Launch Director Michael Leinbach. "I'm disappointed for the team today, for sure. But as we always say, and it's absolutely the truth, we're going to fly when we're ready and clearly we were not ready to fly today. So we'll come back another day and try it again."

Asked if Discovery was "jinxed" given the problems that have repeatedly delayed the veteran orbiter this week, Leinbach said "it's a machine and every now and then machines break and right now, our machine is broken, and we need to go fix it."

"No, we're not jinxed at all," he said. "We're just dealing with one problem after another. Does it get frustrating? It's frustrating, because we'd rather be launching and getting up to the space station, sure."

The leak developed during fueling for a planned 3:04 p.m. EDT launch. Sensors near the vent line indicated a "significant" leak with gaseous hydrogen concentrations of more than 60,000 parts per million. Leinbach said the concentration actually was higher than that, but the sensors only go up to 6 percent. Launches are not allowed to proceed with concentrations higher than 4 percent.

Leaks in the vent line attachment fitting, called a ground umbilical carrier plate, or GUCP, delayed two earlier shuttle missions in 2009, but extensive corrective actions were taken and engineers believed the problem was resolved.

The earlier leaks began when the tank was full and the hardware in the vent line had been chilled to cryogenic conditions. The leak Friday developed much earlier, while the tank was being filled, and the leak rate was much higher.

Engineers cycled a valve inside the quick-disconnect fitting in a bid to clear out any ice or other contamination that might have caused the leakage. But the system remained out of limits, violating both NASA's launch commit criteria and ground safety rules.

Leinbach and Mike Moses, chairman of NASA's Mission Management Team, then decided to call off the countdown, delaying launch.

Engineers quickly began assessing possible repairs in hopes of making another launch attempt Monday, the last day in Discovery's current launch window. But the timeline was tight and engineers will not even get their hands on the hardware to find out what went wrong until Saturday.

Complicating the picture, a launch Monday would have required changes to the shuttle's space station resupply mission because of temperature issues related to the lab's orbit.

Instead, Moses said, the management team decided to give up on Monday and to press instead toward at launch at the opening of the year's final shuttle launch window on Nov. 30.

At about the same time, engineers inspecting Discovery's external tank spotted a 7-inch crack in the foam insulation near the top of the intertank region on the side of the tank facing the shuttle.

It's not yet clear what caused the crack or what, if anything, might be needed to repair it. But given that it's on the same side of the tank as the shuttle, repairs likely will be required. Whether that work can be done at the pad, where access is difficult, remains to be seen.

Discovery's crew, meanwhile -- commander Steven Lindsey, pilot Eric Boe, Michael Barratt, Nicole Stott and spacewalkers Timothy Kopra Alvin Drew -- broke quarantine and flew back to the Johnson Space Center in Houston after the delay was announced.

"It's a frustrating thing, but it's a good thing, right?" Moses said, referring to the prospect of not detecting a major problem. "Obviously, these things happen, it's the way the space business works and the team is very good at rolling with the punches."

The vent line is used to carry excess hydrogen gas away from the shuttle when the tank is filled with super-cold propellant. A valve used to route hydrogen to the vent line is closed a few minutes before launch when the tank is pressurized for flight.

In the most recent previous GUCP leak, the shuttle Endeavour was grounded June 13 and 17, 2009, when sensors near the umbilical attachment plate detected hydrogen concentrations of more than 6 percent.

After the second launch scrub, engineers collected detailed measurements and concluded the problem was caused by an alignment issue between the hydrogen vent port on the tank and the vent line interface. To ensure a tight fit, engineers replaced a rigid Teflon seal with a more flexible design, modified the umbilical plate mounting pins and installed washer-like shims to counteract the alignment issue.

The shims provided additional pressure on one side of the attachment fitting that was believed to be pulling away slightly as the hardware contracted under cryogenic conditions.

The fix worked, Endeavour was safely launched in July 2009 and no other GUP problems occurred before Discovery's fueling Friday.

Discovery's launch originally was scheduled for Monday, but the flight was delayed to Tuesday and then Wednesday by work to replace suspect quick-disconnect fittings in the pressurization system of Discovery's right-side orbital maneuvering system rocket pod. Then, during checkout of the avionics used to control Discovery's three main engines, an electrical glitch was encountered that prompted a 24-hour delay to Thursday.

After a detailed engineering review, NASA managers decided the unexpected electrical "signature" was not a threat and Discovery was cleared for launch. But the weather refused to cooperate, and NASA's Mission Management Team decided early Thursday to order another 24-hour delay to Friday.

Overnight, yet another problem cropped up. Engineers spotted loose covers over three maneuvering rocket thruster nozzles in the shuttle's nose section. Concerned about water intrusion and the possibility of ice in orbit, engineers moved a rotating gantry back into place around Discovery and engineers attached new covers. The rotating service structure was moved away again around 2:20 a.m. to clear the way for fueling.

The next launch window opens Nov. 30 and closes Dec. 5 or 6. If Discovery isn't off the ground by then, the flight likely will slip to the end of February, pushing launch of the shuttle Endeavour into late April or early May. NASA's final shuttle flight, a station resupply mission with Atlantis, is targeted for next summer.

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CBS NEWS Coverage of Breaking Space News

By William HARWOOD
CBS News Space Consultant

Shuttle Launch Director Michael Leinbach has told NASA and contractor engineers that launch of the shuttle Discovery will be delayed to Nov. 30, the opening of the year's final launch window, because of work to repair a leaking hydrogen vent line.

Engineers also are assessing a large crack in the foam insulation in the intertank region of Discovery's external tank that was spotted after engineers began draining the tank earlier Friday.

NASA managers had held out hope initially that engineers could possibly repair the vent line in time for a launch attempt Monday, the final day of the current window. But after additional engineering assessments, Leinbach decided to push launch back to Nov. 30 to give the team more time to assess the problem and take corrective action.

Additional details will be posted as they become available.

=================================

CBS NEWS Coverage of Breaking Space News

By William HARWOOD
CBS News Space Consultant

Engineers have found an 8-inch crack in the intertank section of the shuttle Discovery's external tank, sources said, indicating another major problem that threatens tentative plans to ready the ship for launch Monday. The crack in two rib stringers was spotted after NASA managers ordered a launch scrub because of a hydrogen leak in a 7-inch vent line attached to the left side of the intertank area. Whether the crack is related to the leak or not is not known. It also is not known whether the crack penetrates the metal structure of the stringers in question or foam insulation on the outer surface.

Two shuttle missions were delayed in 2009 by hydrogen leaks at the ground umbilical carrier plate quick-disconnect fitting and it's not yet known what the problem might be with Discovery's vent line. Even without the additional burden or a crack repair, the timeline is extremely tight for a Monday launch attempt.

Additional details will be posted here as they become available.

==================================

CBS NEWS Coverage of Breaking Space News

By William HARWOOD
CBS News Space Consultant

A "significant" hydrogen leak in a vent arm attached to the shuttle Discovery's external tank will delay another launch attempt until at least Monday, the final day of the current launch window, NASA officials said Friday. If Discovery is not off the ground by then, launch will be delayed to Nov. 30, the opening of the year's final shuttle launch opportunity.

Engineers are draining the shuttle's external tank in preparation for gaining access to the hydrogen vent line over the weekend. Launch Director Michael Leinbach said the magnitude of the leak was so high engineers suspect they will find an obvious defect when the mechanism is disassembled for an inspection.

"The signature of the leak is similar to what we've seen in the past when we've had leaks there, although the magnitude was higher this time and it occurred earlier in our tanking process," said Leinbach. "It actually occurred during fast-fill where in the past we'd gotten into a topping regime before the leak occurred."

Engineers cycled the vent valve in the mechanism in hopes of clearing whatever might be preventing a tight seal, but the leak persisted and Leinbach ordered a launch scrub at 8:11 a.m. EDT (EDT=GMT-4).

"The leak followed the vent valve cycling very closely, every time we cycled the vent we saw the leak, so that's indicative of something going wrong down inside of that quick-disconnect," Leinbach said.

It will take almost a full 24 hours to drain and "inert" the huge external tank, preventing inspections and troubleshooting until Saturday.

"It's my hope that given the magnitude of the leak that once we get the GUCP (gaseous umbilical carrier plate) taken apart, we'll see something wrong that's obvious to us, go fix it, put it back together and get a launch attempt before the end of this window," Leinbach said. "That's my hope. I'm not sure that's how it's going to turn out, but that's the challenge that we've put out to the team."

In the meantime, he said, launch was off until at least Monday.

"We've gone officially into a 72-hour scrub turnaround, knowing that's our last launch attempt in this window," Leinbach said. "There's certain tricks that we might be able to do when we pull the GUCP apart that says you get to the work quicker. A lot of the engineering contingent are going to want to take very, very detailed measurements as we're taking this thing apart, and that may end up being what we do. If we do all that detailed work, that probably extends the timeline because that's what we did in the past to get to that 72 hours.

"So we're not going to push the team, but we have asked them if 'is there anything you can do in a 72 to get to that launch attempt on Monday' because a lot of us believe that given the magnitude of the leak we're going to see something obvious when we get it apart. If that's the case, then we'll change out whatever has gone wrong and put it back together and hopefully that supports Monday."

NASA's Mission Management Team will meet Saturday to discuss repair options and whether to press ahead for a Monday launch attempt.

"We're going to get together later this morning with the OPS and engineering teams, review that kind of top-level assessment, top-level plan that we've asked (the team to carry out)," Leinbach said. "Then the detailed engineering reviews and troubleshooting plans will kick in later this afternoon. We'll present that to the program tomorrow sometime, what the actual options are. We won't know what's gone wrong with the GUCP until we get our hands on it, which will be tomorrow afternoon.

"So right now it's a lot of speculation, but obviously the hardware was talking to us, it leaked significantly and it was a case where we were violating not only launch commit criteria but also some of our ground safety requirements -- limits on hydrogen in free air. So we elected to scrub, obviously, and that was the best course of action."

================================

CBS NEWS Coverage of Breaking Space News

By William HARWOOD
CBS News Space Consultant

A leak in the gaseous hydrogen umbilical that connects a vent line, called the ground umbilical carrier plate, or GUP, to the side of the shuttle Discovery's external tank has forced NASA to call off the countdown for today's planned launch. It is not yet known what might be needed to repair the problem or whether another launch attempt can be made before the current launch window closes Sunday or, possibly, Monday.

"We have officially scrubbed today's launch attempt," said NASA commentator Allard Beutel. "The launch team here in Firing Room No. 4 is currently in the process of draining the external tank."

Problems with the ground umbilical carrier plate caused lengthy delays for two shuttle missions in 2009. There have not been any problems with the system since then.

The vent line is used to carry excess hydrogen gas away from the shuttle when the tank is filled with super-cold propellant. A valve used to route hydrogen to the vent line is closed a few minutes before launch when the tank is pressurized for flight.

In the most recent previous GUP leak, the shuttle Endeavour was grounded June 13 and 17, 2009, when sensors near the umbilical attachment plate detected hydrogen concentrations of more than 60,000 parts per million, or 6 percent. The allowable concentration near the shuttle is 4 percent.

After the second launch scrub, engineers collected detailed measurements and concluded the problem was caused by an alignment issue between the hydrogen vent port on the tank and the vent line interface. To ensure a tight fit, engineers replaced a rigid Teflon seal with a more flexible design, modified the umbilical plate mounting pins and installed washer-like shims to counteract the alignment issue.

The shims provided additional pressure on one side of the attachment fitting that was believed to be pulling away slightly as the hardware contracted under cryogenic conditions.

The fix worked, Endeavour was safely launched in July 2009 an no other GUP problems occurred before Discovery's fueling Friday.

Discovery's current launch window closes Sunday. The next launch window opens Dec. 1.

=================================

CBS NEWS Coverage of Breaking Space News

By William HARWOOD
CBS News Space Consultant

A leak in the gaseous hydrogen umbilical that connects a vent line, called the ground umbilical carrier plate, or GUP, to the side of the shuttle Discovery's external tank has forced NASA to call off the countdown for today's planned launch. It is not yet known what might be needed to repair the problem or whether another launch attempt can be made before the current launch window closes Sunday or, possibly, Monday.

"We have officially scrubbed today's launch attempt," said NASA commentator Allard Beutel. "The launch team here in Firing Room No. 4 is currently in the process of draining the external tank."

Problems with the ground umbilical carrier plate caused lengthy delays for two shuttle missions in 2009. There have not been any problems with the system since then.

The earlier leaks apparently were caused by a slight misalignment in the rectangular vent port housing that prevented the umbilical plate that attaches the vent line from forming a tight seal when the hardware was exposed to ultra-low temperatures.

To fix the problem, a different type of seal was installed in the vent line quick-disconnect system, one that is more flexible, and shim-like washers were installed on the umbilical plate mounting points to provide additional pressure on the side believed to be pulling away slightly as the hardware contracted under cryogenic conditions.

Discovery's current launch window closes Sunday. The next launch window opens Dec. 1.

=================================

CBS NEWS Coverage of Breaking Space News

6:20 AM 11/05/10 Update: Shuttle fueling underway; weather 70 percent 'go' for launch

By William HARWOOD
CBS News Space Consultant

Engineers began pumping a half-million gallons of supercold liquid oxygen and hydrogen rocket fuel into the shuttle Discovery's external tank early Friday, setting the stage for launch on an 11-day space station resupply mission, the orbiter's 39th and final flight. Liftoff is targeted for 3:04:01 p.m. EDT.

Forecasters are predicting a 70 percent chance of acceptable weather, with the only concern being possible 24-knot headwinds at the shuttle runway in the wake of a cold front that moved through the area Thursday. The forecast calls for a 60 percent chance of good weather Saturday, dropping to 40 percent "go" on Sunday, the final opportunity in the current launch window.

"The launch teams are not working any issues right now that would prevent us from launching on time this afternoon," said NASA commentator Allard Beutel. "The mission management team gave unanimous approval to go ahead with fueling operations."

Working by remote control, engineers began the three-hour fueling procedure at 5:58 a.m., pumping liquid hydrogen and oxygen through transfer lines leading to the shuttle's aft engine compartment and from there, into the huge external tank. The procedure began 20 minutes late because of overnight work to replace three loose rocket nozzle rain covers.

If all goes well, commander Steven Lindsey, pilot Eric Boe, Nicole Stott, Michael Barratt and spacewalkers Timothy Kopra and Alvin Drew will begin strapping in around 11:43 a.m. to await liftoff on the 133rd shuttle mission.

The primary goals of Discovery's mission are to deliver a new cargo module, loaded with supplies and equipment, to the International Space Station along with an external storage platform and a spare set of cooling system radiators.

Launch originally was scheduled for Monday, but the flight was delayed to Tuesday and then Wednesday by work to replace suspect quick-disconnect fittings in the pressurization system of Discovery's right-side orbital maneuvering system rocket pod. Then, during checkout of the avionics used to control Discovery's three main engines, an electrical glitch was encountered that prompted a 24-hour delay to Thursday.

After a detailed engineering review, NASA managers decided the unexpected electrical "signature" was not a threat and Discovery was cleared for launch. But the weather refused to cooperate, and NASA's mission management team decided early Thursday to order another 24-hour delay to Friday.

Overnight, yet another problem cropped up. Engineers spotted loose covers over three maneuvering rocket thruster nozzles in the shuttle's nose section. Concerned about water intrusion and the possibility of ice in orbit, engineers moved a rotating gantry back into place around Discovery and engineers attached new covers. The rotating service structure was moved away again around 2:20 a.m.

Discovery's launch window closes Sunday or, possibly, Monday if engineers can resolve concerns about high heating once docked with the space station. If the shuttle isn't off the ground by Sunday, the flight will be delayed to Nov. 30 or Dec. 1, the opening of the year's final shuttle launch window.

Here is a timeline of the remaining countdown milestones. All times before the final hold at T-minus nine minutes are one minute earlier than (in EDT and launch-minus time; best viewed with fixed-width font):

EDT...........EVENT

08:38 AM......Begin 2-hour 30-minute built-in hold (T-minus 3 hours)
08:38 AM......Closeout crew to white room
08:38 AM......External tank in stable replenish mode
08:41 AM......Ascent flight control team on console
08:53 AM......Astronaut support personnel comm checks
09:23 AM......Pre-ingress switch reconfig
09:30 AM......NASA TV launch coverage begins
10:33 AM......Final crew weather briefing
10:43 AM......Crew suit up begins
11:08 AM......Resume countdown (T-minus 3 hours)

11:13 AM......Crew departs O&C building
11:43 AM......Crew ingress
12:33 PM......Astronaut comm checks
12:58 PM......Hatch closure
01:28 PM......White room closeout

01:48 PM......Begin 10-minute built-in hold (T-minus 20m)
01:58 PM......NASA test director countdown briefing
01:58 PM......Resume countdown (T-minus 20m)

01:59 PM......Backup flight computer to OPS 1
02:03 PM......KSC area clear to launch

02:09 PM......Begin final built-in hold (T-minus 9m)
02:34 PM......NTD launch status verification
02:55:01 PM...Resume countdown (T-minus 9m)

02:59:01 PM...Orbiter access arm retraction
02:59:01 PM...Launch window opens
02:59:01 PM...Hydraulic power system (APU) start
02:59:06 PM...Terminate LO2 replenish
03:00:01 PM...Purge sequence 4 hydraulic test
03:00:01 PM...Inertial measurement units to inertial
03:00:06 PM...Aerosurface profile
03:00:31 PM...Main engine steering test
03:01:06 PM...LO2 tank pressurization
03:01:26 PM...Fuel cells to internal reactants
03:01:31 PM...Clear caution-and-warning memory
03:02:01 PM...Crew closes visors
03:02:04 PM...LH2 tank pressurization
03:03:11 PM...SRB joint heater deactivation
03:03:30 PM...Shuttle flight computers take control of countdown
03:03:40 PM...SRB steering test
03:03:54 PM...Main engine start (T-6.6 seconds)
03:04:01 PM...SRB ignition (LAUNCH)

=================================

CBS NEWS Coverage of Breaking Space News

6:55 AM, 11/04/10 Update: Shuttle launch delayed to Friday

By William HARWOOD
CBS News Space Consultant

Editor's note: CORRECTING weather forecast odds for Friday and Saturday

With rain showers and low clouds sweeping over NASA's Florida spaceport, agency managers decided early Thursday not to fuel the shuttle Discovery, delaying launch another 24 hours to Friday at 3:04 p.m. EDT. While conditions will improve in the wake of a cold front, forecasters are predicting a 40 percent chance of high winds that could cause another scrub.

NASA's Mission Management Team made the decision to delay launch after a 5:30 a.m. telecon and a weather briefing that called for a broken decks of clouds at 3,000 and 6,000, overcast at 15,000 feet, winds out of 240 degrees at 13 knots with gusts to 20 and showers within 20 nautical miles of the runway.

The low clouds, showers and winds were in violation of NASA flight safety rules and the Mission Management Team decided to call off Thursday's launch attempt.

"Our team was prepared and ready to execute tanking this morning," said Pete Nickolenko, the assistant launch director. "Our tanking weather would have been acceptable, however the launch forecast continues to be poor, with solid rain showers forecast throughout the course of the day. ... The team concluded it was not prudent to pick up with tanking today. At this point, we're going to be inserting a 24-hour delay in our countdown procedures."

The forecast for Friday calls for few clouds and no rain. But shuttle weather officers are predicting winds out of 330 degrees at 17 knots with gusts to 26, a violation of the launch weather guidelines. The overall forecast calls for a 40 percent chance of local weather prohibiting launch. The odds are 60 percent "no-go" on Saturday.

"The weather forecasters did indicate this frontal system should pass through later tonight and of course, on the backside of a cold front we'll get drier weather. Of course, it'll be windier, too, so we'll be watching the winds tomorrow to see what the launch winds and the potential headwind issues may be, if any, for us. And then also we'll be watching the upper level winds."

As it now stands, engineers plan to begin fueling Discovery at 5:39 a.m. Friday. The shuttle's six-member crew -- commander Steven Lindsey, pilot Eric Boe, Nicole Stott, Michael Barratt and spacewalkers Timothy Kopra and Alvin Drew -- will begin strapping in around 11:44 a.m. to await liftoff at 3:04:00 p.m.

Discovery's current launch window closes Sunday due to temperature constraints after the shuttle is docked to the International Space Station. Flight controllers are assessing whether the window could be extended another day or so, but that has not yet been decided.

Either way, if Discovery does not get off during the current window, the flight will be delayed to December. The year's final shuttle window opens Dec. 1 and closes Dec. 5.

=================================

CBS NEWS Coverage of Breaking Space News

By William HARWOOD
CBS News Space Consultant

Despite threatening weather, NASA managers Wednesday cleared the shuttle Discovery for launch Thursday on its 39th and final mission, deciding an electrical glitch that prompted a 24-hour delay was not a threat to flight safety. Liftoff was targeted for 3:29:43 p.m. EDT.

NASA's mission management team reviewed an engineering assessment that concluded the electrical problem was most likely caused by "transient contamination" in a circuit breaker. Critical equipment on that circuit operated normally after the breaker was cycled several times and there have been no other signs of trouble.

"At the end of the day, I'll kind of cut to the chase and say we wrapped up with a unanimous poll out of the MMT, no dissenting opinions, no requests for additional data, everybody was very comfortable with the story that came together today," said Mike Moses, chairman of the mission management team.

"Really, the rationale there is all the evidence points to this being a circuit breaker problem, a power supply feed problem, it's not a controller problem so it's not a main engine controller. So no worries there the main engine controller itself is going to have problems later on."

While Discovery appears to be in good shape, dismal weather is on tap Thursday with high winds expected Friday and Saturday.

With a frontal system moving through the area, forecasters are predicting an 80 percent chance of low clouds and rain that would prohibit a launching Thursday. High winds are expected Friday and Saturday, with forecasters putting the odds of acceptable weather at 60 percent and 40 percent respectively.

The shuttle's current launch window runs through Sunday. After that, the angle between the sun and the plane of the station's orbit would result in higher-than-allowable heating of the shuttle after docking. The year's final shuttle launch window opens Dec. 1 and closes five days later.

Hoping for the best, engineers were cleared to roll a protective gantry away from Discovery late Wednesday, after a delay because of a lightning advisory, setting the stage for the start of fueling at 6:04 a.m. Thursday.

Mission managers will meet at 5:30 a.m. to assess the weather.

"The weather still looks really bad for tomorrow," Moses said. "But we're going to go ahead and go down to the tanking telecon in the morning. ... If the forecast tomorrow morning is still as bad as it is today, there's a chance we might decide not to spend one of our (launch) opportunities tomorrow. But it's too early to make that call right now."

Hoping for the best, Discovery's six-member crew -- commander Steven Lindsey, pilot Eric Boe, Michael Barratt, Nicole Stott and spacewalkers Timothy Kopra Alvin Drew -- plans to begin strapping in around 12:09 p.m. to await liftoff.

Assuming an on-time launch, Lindsey will guide Discovery to a docking with the International Space Station around 11:29 a.m. on Nov. 6. Spacewalks by Kopra and Drew are scheduled for Nov. 8 and 10. If all goes well, Discovery will undock from the lab complex around 5:27 a.m. on Nov. 13, setting up a landing back at the Kennedy Space Center at 10:24 a.m. on Nov. 15.

Engineers started Discovery's final countdown Monday after working through the weekend to replace and retest leaking quick-disconnect fittings in the shuttle's right-side orbital maneuvering system rocket pod. That work forced NASA to delay launch from Monday to Tuesday and, eventually, to Wednesday.

Launch was delayed 24 hours to Thursday after engineers ran into problems with a circuit associated with a control computer mounted on one of Discovery's three hydrogen-fueled main engines. One of the controller's two channels did not power up when a switch was thrown. An hour and 45 minutes later, the controller powered up on its own.

Engineers then powered down the controller and cycled the circuit breaker five times. They also turned the controller off and on. A switch was then cycled five times and then re-powered the controller. There were no problems.

An hour and 45 minutes after that, however, telemetry indicated a 5-volt drop in the circuit for a brief 180 milliseconds. The drop was within design specification, but it was unusual and mission managers ordered a 24-hour delay to gain a better understanding of the overall issue.

As it turned out, Moses said, the engineering analysis showed that short voltage drops are not unusual and that very slight changes in the operation of other equipment on the circuit can produce similar signatures.

"Another big piece of data that got us comfortable today was the fact that it's not all that uncommon," he said. "And so again, when we laid it all out it all racked up to be pretty clear that our most probable cause here is we had contamination on that circuit breaker, that we slowly cleared it off by scrubbing (cycling) it. In fact, after we left last night, we scrubbed it five more times. Those power-up signatures were perfect.

"So, pretty good proof that we knocked the contamination off. Our history shows us that once we do that, that is a solid connection and it's not going to change and therefore we had pretty good acceptance rationale today to go fly."

Each main engine is equipped with a controller that monitors engine operation -- valve positions, temperatures, pressure, vibration and other factors -- 50 times per second. Those data are fed to the shuttle's flight computers and if a problem develops, an engine can be safely shut down before a catastrophic failure occurs.

If a controller channel fails before launch, a countdown hold or an on-pad abort would result. If a controller channel fails after liftoff, the affected engine would continue operating with a single channel. A second failure, however, would trigger an automatic engine shutdown and abort.

But the engineering review determined the electrical anomalies in the backup channel of main engine No. 3's controller were most likely the result of transient contamination in a circuit breaker located in the shuttle's cockpit behind the commander's seat.

"Given history of contamination issues in circuit breaker operation, signature of failure seen in this launch countdown is most probable cause," according to an MMT presentation.

"System behavior following last circuit breaker cycling indicates a strong conducting contact surface across all three phases."

=================================

CBS NEWS Coverage of Breaking Space News

1:00 PM, 11/03/10 Update: NASA managers await engineering review to decide shuttle launch strategy

By William HARWOOD
CBS News Space Consultant

With the shuttle Discovery's countdown on hold, engineers reviewed historical data and refined a "fault tree" to understand what caused irregularities in a critical circuit Tuesday, delaying launch to at least Thursday.

NASA's mission management team plans to meet at 2 p.m. EDT (EDT=GMT-4) to review overnight progress and to make a decision on whether to launch Discovery as is Thursday or to stand down for repairs.

While the weather forecast does not normally play a roll in launch decisions, it could be a factor in this case. Meteorologists are predicting dismal conditions Thursday with high winds expected Friday and Saturday.

With a frontal system moving through the area, forecasters are predicting an 80 percent chance of low clouds and rain that would prohibit a launching Thursday. High winds are expected Friday and Saturday, with forecasters putting the odds of acceptable weather at 60 percent and 40 percent respectively.

The shuttle's current launch window runs through Sunday, with a possible extension to Monday. If Discovery isn't off the ground by then, launch would slip to Dec. 1, the opening of the year's final shuttle launch window.

If the MMT decides to proceed with a Thursday launch attempt, engineers will roll a protective gantry away from Discovery around 7 p.m. Wednesday, exposing the orbiter to view and setting the stage for the start of fueling at 6:04 a.m. Thursday.

Discovery's six-member crew -- commander Steven Lindsey, pilot Eric Boe, Michael Barratt, Nicole Stott and spacewalkers Timothy Kopra Alvin Drew -- would begin strapping in around 12:09 p.m. to await liftoff at 3:29:43 p.m.

Assuming an on-time liftoff, Lindsey would guide Discovery to a docking with the International Space Station around 11:29 a.m. on Nov. 6. Spacewalks by Kopra and Drew would be scheduled for Nov. 8 and 10. If all goes well, Discovery would undock from the lab complex around 5:27 a.m. on Nov. 13, setting up a landing back at the Kennedy Space Center at 10:24 a.m. on Nov. 15.

Launch was delayed 24 hours to Thursday after engineers ran into problems with a circuit associated with a control computer mounted on one of Discovery's three hydrogen-fueled main engines. One of the controller's two channels did not power on normally. Later, after it was operating, telemetry showed a brief, unexpected voltage drop.

Each main engine is equipped with a controller that monitors engine operation -- valve positions, temperatures, pressure, vibration and other factors -- 50 times per second. Those data are fed to the shuttle's flight computers and if a problem develops, an engine can be safely shut down before a catastrophic failure occurs.

Engineers suspect the electrical anomalies in the backup channel of main engine No. 3's controller were the result of "transient contamination" in a circuit breaker. The breaker in question was cycled five times overnight and the circuit was used to power up the shuttle's master events controllers. The engine controller has operated normally ever since it was activated.

But Mike Moses, chairman of the mission management team, said Tuesday that engineers needed to come up with an explanation of what went wrong in the first place and develop a solid flight rationale before Discovery will be cleared for launch.

"Does it make sense that a circuit breaker with a little bit of a bad contact explains both of these signatures that we saw? The community feels pretty confident that that is the case, but they do need time to polish that story," Moses said Tuesday.

He emphasized that NASA would not let the relatively short launch window drive a decision to launch Discovery if the engineering data do not support show it is safe to do so.

"If tomorrow we come in and go we either still don't understand it or we understand it and we need to fix it, then we're going to do that," he said. "We're not just going to fly as is."

=================================

CBS NEWS Coverage of Breaking Space News

By William HARWOOD
CBS News Space Consultant

The shuttle Discovery's launch on a space station resupply mission Wednesday was delayed at least 24 hours, to no earlier than 3:29:43 p.m. EDT Thursday, to give engineers more time to troubleshoot an apparent electrical glitch in circuitry associated with a backup main engine computer.

"It's another day in paradise," joked Launch Director Michael Leinbach after the countdown was extended. "This is part of the business, you fly when you're ready and you don't if you're not, and we're not ready to go."

"Discovery's not going out easy," he said, referring to the orbiter's 39th and final flight. "She's giving us a little bit of trouble. But that's fine. She'll fly perfectly when she does."

If no major repairs are needed and engineers can get comfortable launching Discovery as is, commander Steven Lindsey and his five crewmates could be cleared for launch Thursday, weather permitting. Forecasters are predicting a 70 percent chance of low clouds and rain from an approaching frontal system that could block a launch attempt. The forecast improves to 70 percent "go" on Friday.

Regardless of the dismal forecast, Mike Moses, chairman of NASA's Mission Management Team, said the engineering community needed the extra day to review historical data, flight rules and performance specifications to determine if the system can be launched as is, or whether more extensive repairs might be needed.

If repairs are needed, engineers will be hard pressed to complete the work before the current launch window closes. As of this writing, the window closes Sunday, with a possible extension to Monday. If Discovery isn't off the ground by then, launch will slip to Dec. 1, the opening of the year's final shuttle launch window.

"We don't fly with unknown risk and right now, this risk is still a little bit unknown to us," Moses said. "We're going to take another day to get to know it better, for lack of a better word, and make this a known risk that we do understand and that we've quantified.

"I think we could have gotten there, I think the data is there, but it's really the better part of valor to let them have the time to go put that story together in a nice, crisp package that we can walk through tomorrow."

He said engineers are developing repair scenarios, but the focus is on developing "the rationale to fly in the condition that we're in."

"If that rationale tomorrow doesn't sound good enough, we'll see what more time we need to make it a story we are comfortable with," he said. "And ultimately, if we find that we cannot get comfortable with the scenario we have, then we'll go down the path of R & R (removal and replacement)."

Engineers started Discovery's final countdown Monday after working through the weekend to replace and retest leaking quick-disconnect fittings in the shuttle's right-side orbital maneuvering system rocket pod. That work forced NASA to delay launch from Monday to Tuesday and, eventually, to Wednesday.

Once underway, the countdown ticked smoothly through its initial hours. But during work to power up and check out Discovery's main engine electronics early Tuesday, engineers ran into problems with a circuit powering one of two channels in main engine No. 3's controller.

Each of the shuttle's three hydrogen-fueled main engines is equipped with a two-channel controller that monitors engine operation 50 times per second during ascent, relaying the data to the shuttle's flight computers.

If the controllers spot a problem, an engine can be safely shut down before a catastrophic failure can occur. Given the critical nature of the controllers, NASA flight rules require both redundant channels in each controller to be operating normally for a launch to proceed.

During checkout early Tuesday, the backup channel of main engine No. 3's controller did not power on when a switch was thrown. A bit later, the controller powered up on its own, the sort of signature that can indicate contamination in a circuit breaker.

After initial troubleshooting, engineers cycled the circuit breaker in a bid to clear any "transient contamination." The controller then was powered back on and it appeared to be working normally.

But the picture was complicated about 90 minutes later when telemetry indicated an unexpected, very brief voltage drop in the same circuit. Engineers now are trying to determine whether a transient issue with the circuit breaker could explain both signatures.

Moses said he is optimistic the system is healthy. The voltage drop was well within design specifications and he said had it occurred during engine startup, launch would have proceeded normally.

"Running through all that, they got to a really good story and I think if we would have had about a nine-hour MMT, we could have heard all that data, judged it all and been good to fly," he said. "But that's not the right thing to do for this team, to try to then come in in the morning to try to tank and launch.

"So it was a pretty easy decision to say we're getting really close to having a really good understanding of the problem, but we need to polish it, we need to organize it, we need to make sure we're not wrong about it."

Even though engineers believe they understand the problem, Moses said he wanted a thorough understanding of "what if we're wrong, what's going to happen if this controller does flake out, either in the count Thursday or once we start going up hill after launch?"

"The other big piece of that is to make sure we're not, to put it bluntly, crafting a solution that matches what we think the problem is and that we're actually having a good physics based understanding of the phenomenon.

"Does it make sense that a circuit breaker with a little bit of a bad contact explain both of these signatures that we saw? The community feels pretty confident that that is the case, but they do need time to polish that story."

He emphasized that NASA would not let the relatively short launch window drive a decision to launch Discovery if the engineering data do not support show it is safe to do so.

"If tomorrow we come in and go we either still don't understand it or we understand it and we need to fix it, then we're going to do that," he said. "We're not just going to fly as is."

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CBS NEWS Coverage of Breaking Space News

By William HARWOOD
CBS News Space Consultant

The shuttle Discovery's launch on a space station resupply mission Wednesday was delayed at least 24 hours, to no earlier than 3:29:43 p.m. EDT Thursday, to give engineers more time to troubleshoot an apparent electrical problem with circuitry associated with a backup main engine computer.

NASA's mission management team met late Tuesday to discuss the problem and possible solutions. Sources said the voltage irregularities were very small and within engineering specifications. But the signature was unexpected, prompting extensive troubleshooting.

If no major repairs are needed, or if engineers can get comfortable launching Discovery as is, commander Steven Lindsey and his five crewmates could be cleared for launch Thursday, weather permitting.

But forecasters are predicting a 70 percent chance of low clouds and rain from an approaching frontal system Thursday that could block a launch attempt. The forecast improves to 70 percent "go" on Friday.

The current launch window closes Sunday with a possible extension to Monday. The final shuttle launch window this year opens Dec. 1 and closes Dec. 5.

Engineers started Discovery's final countdown Monday after working through the weekend to replace and retest leaking quick-disconnect fittings in the shuttle's right-side orbital maneuvering system rocket pod. That work forced NASA to delay launch from Monday to Tuesday and, eventually, to Wednesday.

Once underway, the countdown ticked smoothly through its initial hours. But during work to power up and check out Discovery's main engine electronics early Tuesday, engineers ran into problems with a circuit powering one of two channels in a computer controller mounted on main engine No. 3.

Troubleshooting indicated unusual voltage readings may have been the result of "transient contamination" in a switch or circuit breaker. After power cycling the circuit, engineers activated the controller and it powered up normally.

But later Tuesday morning, the telemetry stream showed a brief, unexpected, five-volt drop in the same circuit, a signature engineers had not seen before. Additional troubleshooting was ordered even though the engine controller continued to operate normally.

Each of the shuttle's three hydrogen-fueled main engines is equipped with a two-channel controller that monitors engine operation 50 times per second during ascent, relaying the data to the shuttle's flight computers. If the controllers spot a problem, the flight computers can safely shut an engine down before a catastrophic failure can occur.

Given the critical nature of the main engine controller, NASA flight rules require full redundancy and normal operation for a countdown to proceed.

NASA's mission management team met at 5 p.m. to evaluate the issue and possible repair scenarios. Mission managers quickly decided to order a 24-hour delay.

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CBS NEWS Coverage of Breaking Space News

12:55 PM, 11/2/10 Update: Engineers troubleshoot apparent glitch in shuttle engine controller circuitry

By William HARWOOD
CBS News Space Consultant

Engineers readying the shuttle Discovery for launch Wednesday on a space station resupply mission are troubleshooting an apparent electrical problem with circuitry associated with a backup main engine computer.

Engineers said earlier Tuesday the problem had been resolved, but another glitch in the system raised concerns and additional troubleshooting was ordered.

Assuming the problem is resolved, Discovery will be fueled early Wednesday for a launch attempt at 3:52:13 p.m. EDT (EDT=GMT-4), roughly the moment Earth's rotation carries pad 39A into the plane of the space station's orbit.

Forecasters are predicting a 70 percent chance of acceptable weather with a slight chance of low clouds and showers. The forecast drops to 70 percent "no-go" Thursday as a front moves through the area and improves to 70 percent acceptable again on Friday.

Early Tuesday, engineers ran into a problem with the backup computer controller mounted on main engine No. 3. Troubleshooting indicated the problem was related to "transient contamination" in a circuit breaker and NASA Test Director Steve Payne told reporters in a 10:30 a.m. status briefing that after troubleshooting and power cycles, the controller powered up normally and that engineers were closing out paperwork.

But at almost the same time, another anomaly occurred. Sources said a brief, unexpected voltage drop was observed while nothing else of any significance was going on.

Engineers are troubleshooting the issue to determine if the behavior is consistent with contamination in a circuit breaker or whether it indicates a real problem with the backup engine controller or trouble elsewhere in the shuttle's complex circuitry.

"It still could be associated with the same circuit breaker," an official said. "It's just too soon to say."

Each of the shuttle's three hydrogen-fueled main engines is equipped with a two-channel controller that monitors engine operation 50 times a second. That telemetry stream is critical during ascent and NASA flight rules require full redundancy for a launch to proceed.

NASA's mission management team planned to meet at 3 p.m. to discuss the results of ongoing troubleshooting. Engine controllers can be replaced at the launch pad, but it's not clear whether a swap-out and retest could be completed before the current launch window closes Nov. 7. The next available launch period is Dec. 1-5.

But officials said talk of a controller swap out was premature. As of this writing, engineers were not sure where the problem was located or what, if anything, might be needed to clear Discovery for launch Wednesday.

Assuming Discovery is cleared to fly as is, engineers will begin loading a half-million gallons of rocket fuel into Discovery's external tank starting around 6:27 a.m. Wednesday.

Discovery's six-member all-veteran crew -- commander Steven Lindsey, pilot Eric Boe, Michael Barratt, Nicole Stott and spacewalkers Timothy Kopra Alvin Drew -- plans to begin strapping in around 12:32 p.m. to await launch on the 133rd shuttle mission, Discovery's 39th and final flight.

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CBS NEWS Coverage of Breaking Space News

12:45 PM, 11/01/10 Update: Discovery in good shape for launch; forecasters monitor weather

By William HARWOOD
CBS News Space Consultant

NASA managers met Monday to review the shuttle Discovery's readiness for flight and unanimously agreed to press ahead with launch Wednesday, weather permitting, on a voyage to the International Space Station. It will be Discovery's 39th and final mission.

"There's still a certain amount of disbelief that it's really her final launch," said Launch Director Michael Leinbach. "We all know it, we've come to grips with that fact, but it's hard to believe after having Discovery and the rest of the fleet for 30 years flying so well for America. It's difficult to accept emotionally, but rationally we all know it's coming to an end and we need to get on with it."

Forecasters are predicting a 70 percent chance of acceptable weather for launch Wednesday at 3:52:13 p.m. EDT (EDT=GMT-4). But an approaching frontal system from the north and Tropical Storm Tomas to the south are expected to cause problems later in the week.

"We had our L-minus-two mission management team meeting this morning, it went very quickly," said Mike Moses, shuttle integration manager and chairman of the MMT. "We didn't have any technical issues to discuss. We got a good briefing on what's in front of us with some of the fronts coming in and the tropical storm system down to the south. But again, no technical issues, everybody polled 'go' to head into count, no problems whatsoever."

The Spaceflight Meteorology Group at the Johnson Space Center is predicting a chance of showers within 20 nautical miles of the shuttle's emergency runway and a chance of broken clouds at 3,000 feet, both violations of NASA's launch weather criteria. Shuttle weather officer Kathy Winters, speaking to reporters at the Kennedy Space Center, put the odds for acceptable conditions Wednesday at 70 percent.

The forecast for Thursday calls for a broken deck at 3,000 feet and a chance of thunderstorms within 20 nautical miles, resulting in a 60 percent "no-go" prediction. Conditions are expected to improve Friday with a 70 percent chance of acceptable conditions.

Discovery's current launch window extends through Nov. 7 and possibly Nov. 8. The next launch window opens Dec. 1 and closes Dec. 5.

Hoping for the best, Discovery's six-member all-veteran crew plan to deliver a pressurized cargo module loaded with equipment and supplies to the space station, along with an external storage platform carrying a spare set of cooling system radiators.

Assuming an on-time launch, Discovery will dock with the space station around 12:36 p.m. Friday. Two spacewalks are planned, on Nov. 7 and 9, with undocking on tap Nov. 12 at 5:02 a.m. and landing back at the Kennedy Space Center at 9:59 a.m. Nov. 14.

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CBS NEWS Coverage of Breaking Space News

01:45 PM, 11/01/10 Update: STS-133 mission preview

By William HARWOOD
CBS News Space Consultant

The shuttle Discovery and a crew of six veteran astronauts are on track for launch Wednesday to deliver critical spare parts, supplies and a final U.S. module to the International Space Station. It will be Discovery's 39th and final voyage as NASA presses ahead with plans to retire the fleet after just three more missions.

"Discovery's a workhorse, the fleet leader in number of flights, done a lot of famous flights, all the return-to-flight test missions," said commander Steven Lindsey. "Yet when you walk inside Discovery, it still looks like a new car even after almost 30 years of service. It's a great machine, a great vehicle. It's a privilege for us to be able to fly it on the last flight."

After work to fix a small fuel leak in Discovery's right-side orbital maneuvering system rocket pod, senior NASA managers cleared Discovery for takeoff Nov. 1. But the day before the countdown was to begin, unrelated problems with two quick-disconnect fittings in the pressurization system of the right OMS pod prompted a two-day delay. Launch was re-targeted for 3:52:13 p.m. EDT Wednesday (EDT=GMT-4) .

Joining Lindsey on the shuttle's upper flight deck for launch will be pilot Eric Boe, flight engineer Timothy Kopra and Alvin Drew. Strapped in on the ship's lower deck will be Michael Barratt and Nicole Stott. All six astronauts are spaceflight veterans and three of them -- Kopra, Barratt and Stott -- have logged long-duration flights aboard the space station.

"They'll be extremely valuable to have," Drew said of his crewmates. "I liken it to trying to go up Mount Everest without a Sherpa. These guys know where all the trails are and how to get to places, and so I think it was just a coup that we decided to start re-flying space station veterans on space shuttle missions because they're so much more efficient on board the space station."

If all goes well, Lindsey and Boe will oversee a two-day rendezvous with the lab complex. The astronauts will carry out a now-routine heat-shield inspection the day after launch before guiding the shuttle to a docking at the station's forward port around 12:36 p.m. on Nov. 5. It will be Discovery's 13th and final docking.

Waiting to welcome the shuttle astronauts aboard will be Expedition 25 commander Douglas Wheelock, Shannon Walker, Fyodor Yurchikhin, Scott Kelly, Alexander Kaleri and Oleg Skripochka. Kelly will take over as commander of Expedition 26 at the end of November when Wheelock, Walker and Yurchikhin return to Earth. Three fresh crew members are scheduled to arrive in mid December.

Discovery's docking will come almost 12 years and 68,500 orbits since the Nov. 20, 1998, launch of the station's first component, the Russian Zarya module, and 10 years after the first three-man crew arrived aboard a Russian Soyuz spacecraft Nov. 2, 2000. Since then, the space station has been continuously manned by rotating two-, three- and now six-person crews, covering 57,361 orbits as of the anniversary.

"I delivered the airlock on my first flight to space station," Lindsey said in a NASA interview. "It had just barely started and I remember thinking about all of the missions and all the components we still had to fly up there to fully build this thing out. At times it seemed like we were never going to get there. It was just, there were so many missions.

"When I look back at it now and see this fully assembled space station operating with six people and doing all the science and stuff like that, I'm just amazed at what this big team has accomplished and really excited about what it's going to accomplish in the future.

"Getting an opportunity to go up there again, which I never thought was going to happen, and see this fully assembled space station I've worked on most of my professional career here at NASA is just going to be something fantastic. I hope that the rest of the world appreciates what we have."

When Lindsey and his crewmates were named to the crew of shuttle mission STS-133, NASA intended Discovery's flight to be the program's final voyage, following a Bush administration mandate to finish the space station and retire the shuttle fleet by the end of fiscal year 2010.

That somewhat arbitrary deadline was relaxed a bit when Congress, worried about the possibility of schedule pressure on flight safety, promised an additional $600 million in funding to cover shuttle operations through the end of the calendar year. NASA managers later said internal cost-savings initiatives would allow shuttle operations to continue into early 2011 if necessary.

As it turned out, problems with a $2 billion particle physics experiment scheduled for launch aboard the shuttle Endeavour during the next-to-last fight in July forced NASA to revise the end-of-program shuttle manifest.

Because of work to replace the powerful magnet in the particle physics experiment, Endeavour's flight leap-frogged Discovery's, slipping to late November and eventually to Feb. 27, 2011. Discovery's flight, in turn, slipped from mid September to Nov. 1, in part to accommodate work to modify a cargo transport module for permanent attachment to the space station.

Since then, NASA won political support for a third and final mission with the shuttle Atlantis to deliver additional supplies and equipment to the station. That mission, the shuttle program's final voyage, is targeted for launch June 26, 2011.

After the shuttle fleet is retired, NASA will rely on smaller unmanned Russian, European and Japanese cargo ships, along with new commercial spacecraft that are currently in development, to deliver the supplies and equipment needed by the space station to support a full-time crew of six.

"From a logistics standpoint, 2012 is going to be a real challenge for (the station program)," said shuttle Program Manager John Shannon. "If there are delays in any of the new vehicles that are expected to deliver cargo to the station, that problem is just going to be exacerbated. It's hard to compare vehicles and capabilities. But my operations guy said one shuttle flight is roughly equivalent to about seven Progress flights. So if you think about that, you can do pretty well on one shuttle.

"So getting to fly (Atlantis) late is going to give the space station margin from a logistics standpoint to keep six crew (members) up, to keep doing the research, to keep doing the utilization even if some of those new vehicles are delayed by some period of time."

If the Atlantis mission is not launched "and the new vehicles that are going to deliver cargo are delayed and we end up having a logistics shortfall in 2012 and we have to go down to three crew and we're not doing research, we have made a major error in my opinion," Shannon said.

Faced with an uncertain budget, Shannon is struggling to reduce the shuttle workforce as required while maintaining flight safety and maximizing resupply of the space station. Since 2007, the shuttle contractor workforce has been cut from just over 14,000 to 6,439. The civil service workforce has dropped from around 1,800 to 1,139 at present.

"We expect we'll have one more reduction in the team members on the primary contractors in January," Shannon said. "It'll be about 320 people. Then we'll hold where we are from a workforce standpoint because we'll be down to really just the operations team and critical sustaining engineering skills at that point.

"If we end after the February flight, then the final layoffs would be in March, that would take us down to about 300 people total to do transition and retirement activities. If we fly in the summer, then roughly a month after that last flight we would do the same thing."

Despite the layoffs, "the program is very healthy," Shannon said. "But I have a very high sense of paranoia that this is a very difficult time for the team, and we need to be incredibly vigilant and any little noises that you hear you've got to go pay attention to and really make sure you fully understand what is going on. Because it's a very complex process and it's very unforgiving.

"So far, the team has done an outstanding job and we're going to continue to stay focused. The team really wants to preserve the legacy of the shuttle program and end on a really high note."

A FINAL U.S. MODULE FOR THE SPACE STATION

As originally planned, Discovery's flight did not include any spacewalks. But with the schedule revision and the slip to November, NASA managers added two spacewalks, or EVAs, with Kopra and Drew and scheduled additional work to maximize the resupply effort.

"We started out as an eight-day mission," Lindsey said. "We were just going to go up, dock with space station, offload some payloads and (do) a lot of transfer and basically leave station in the best logistic state possible because when we were originally assigned we were going to be the very last shuttle mission.

"They've added a couple of spacewalks to our flight so what we've had to do is lengthen the mission from eight days to eleven days nominal with a plus one if we need it. We're having to pick up and train (for) those two spacewalks, which we hadn't been training for before. We've also added a whole bunch of robotics that go along with that.

"As a result of that, I've had to move crew members into different tasks to make the timeline fit. ... We have a good schedule in place, and we've worked out all those details. It's just going to take us a little bit longer to get there, but we still have a good plan and feel pretty comfortable with what we're doing."

At the heart of the mission is the permanent multi-purpose module, or PMM, that will be carried aloft in Discovery's cargo bay. The Italian-built module, dubbed Leonardo, was originally designed to serve as an up-and-down cargo transport canister that could be temporarily docked to the space station and then returned to Earth aboard the shuttle.

Then called a multi-purpose logistics module, or MPLM, Leonardo was not designed to remain permanently attached to the station. But with shuttle flights coming to a close, program managers ordered modifications, beefing up Leonardo's insulation, adding increased orbital debris shielding and arranging for power, lights and ventilation. The result is the PMM.

"I think it's going to be a really outstanding addition to the station," said Stott. "Anybody who's lived and worked up there has at one time or another felt like wow, if we just had a closet where we could stick this, or we just had designated storage for these particular items it would be such a great thing.

"And I think what it's going to do is provide that, but it's also going to give us the opportunity to go through station and look at where we have stuff and maybe better distribute so we make even more space available. So I think it's going to be a really, really nice addition."

Mounted in Discovery's cargo bay, the PMM measures 21 feet long and 15 feet in diameter and tips the scales at 21,817 pounds, including 6,536 pounds of equipment and supplies. Another 1,568 pounds of station-bound gear was mounted in the shuttle's crew cabin.

The station-bound hardware includes an experiment rack, a heat exchanger for the lab's temperature and humidity control system, a spare pump for the station's internal cooling system, a large fan, a water processing assembly storage tank, a waste water tank and an experimental robot known as Robonaut 2.

Shaped like a human's upper torso, Robonaut 2 weighs about 300 pounds and measures nearly four feet from waist to head and nearly three feet across the shoulders. The robot will be operated remotely by engineers on the ground.

Describing the robot as a technology demonstrator, Barratt said "this is very much a first step. We'll be identifying some breadboard tasks over the next few years to figure out how best to use a humanoid robot in space."

"When you look at some of the tasks we're asked to do, and what a robot could do, you're thinking of things that would be perhaps dangerous for a human to do or repetitive tasks that would wear a human out," he said. "So if you were to go around the station, for instance, and identify scenarios where it was risky to send a human in, whether you had a suspected fire or a toxic release and what you needed was a switch throw or to discharge a fire extinguisher into the right fire port, that's the kind of thing we could eventually envision sending Robonaut in to do.

"I'd much rather send a robot in than go in myself on a gas mask," he said. "But again, we're very early, and we'll be mapping those tasks to the capabilities that Robonaut demonstrates over the years. And it will be years before we figure all this out. So we're excited to see this all start."

Discovery also is carrying up an 8,161-pound external storage platform carrying a folded set of radiators that will serve as a spare in case of future problems with the station's external cooling system. The station features two independent coolant loops that circulate ammonia through huge radiators to dissipate the heat generated by the lab's electronics.

The spare radiator panels weigh 2,475 pounds and are mounted on an external logistics carrier known as ELC-4. Kopra and Stott, operating the station's robot arm, will lift ELC-4 out of Discovery's cargo bay a few hours after docking on flight day three. They will hand it off to Boe, operating the shuttle's robot arm, and then reposition the station arm. After re-grappling the cargo carrier, Kopra and Stott will mount it on the right side of the station's power truss.

The next day, Barratt and Stott will use the station arm to pull the shuttle's heat shield inspection boom out of the cargo bay before handing it off to the shuttle's arm where it will remain for possible use later in the mission. Inside the station, the astronauts will begin work to repair one of the U.S. segment's carbon dioxide removal systems.

Kopra and Drew will end the day by camping out in the station's Quest airlock module at a reduced pressure of 10.2 pounds per square inch. The camp out procedure is used to help purge nitrogen from the bloodstream before spacewalks are conducted in NASA's 5-psi spacesuits.

The first major objective of the mission's first spacewalk on flight day five is to install a 10-foot-long power cord between the Quest airlock and the Harmony module directly across the station on the other side of the Unity module. The power line, which might be needed in the future if Harmony ever needs to be undocked for repairs, cannot be installed after the PMM is attached to Unity's Earth-facing port.

With the power line in place, Kopra and Drew will retrieve a failed ammonia pump module that was left temporarily stowed on the robot arm's mobile base system after a three-spacewalk repair job in August. After moving the module back to a stowage platform, Drew will install a vent line that will be used during the crew's second spacewalk to dump about 10 pounds of residual ammonia overboard.

"It's interesting how this all evolved," Kopra said. "We started out with an eight-day mission, it was going to be a long weekend on space station. Then it evolved into two pretty demanding spacewalks and we're really excited about it, especially because it's so integrated with robotics.

"As many of you know, the stage crew, the folks on space station, replaced a pump module when it broke and did a great job doing that. And they left the disabled pump module installed on a place on station that's not great for bringing it back home. So Mike is going to fly me up to that location, and we'll install that back on a place on space station where they can pull that off and put it in the payload bay on a future shuttle flight."

With the pump module safely stowed, Kopra and Drew plan to carry out a variety of maintenance tasks, adjusting the insulation on the upper Z1 truss, attaching a tool stanchion and a wedge to tilt a camera away from ELC-4, providing additional clearance when hardware arrives aboard future supply ships.

Before ending the spacewalk, Kopra and Drew will open a Japanese container and "fill" it with the vacuum of space in a project known as "message in a bottle."

"It's a Japanese piece of hardware and the intention here is to use this outside space station and all we want to do is open a valve," Kopra said. "It's kind of unique and a thoughtful sort of experiment the Japanese have designed where we're just going to fill it with the vacuum of space. ... Clearly a vacuum is a vacuum whether it's space or if it's in a vacuum chamber here at NASA. But this is a little bit special, especially for the Japanese because it's the vacuum of space. So we'll do that, capture in pictures and provide that to the Japanese once we come home."

The next day, flight day six, Kopra and Barratt, operating the station's robot arm from inside the multi-window cupola, plan to pull the PMM out of Discovery's payload bay and attach it to Unity's Earth-facing port. That afternoon, a block of time is set aside for a so-called "focused" inspection of the shuttle's heat shield if any problems are spotted after launch or during approach to the station.

That night, Kopra and Drew will camp out in Quest to prepare for another spacewalk the next morning.

The goals of the second excursion are to vent residual ammonia from the failed pump module, to retrieve a European experiment package from the outboard end of the Columbus laboratory module, to install protective lens covers on external cameras that could be "plumed" by approaching cargo ships and to troubleshoot problems with mounting hardware that could be needed in the future for radiator repairs or replacement.

Inside the station, the astronauts will complete outfitting the vestibule between Unity and the PMM, opening the hatch and floating inside for the first time. Unlike normal MPLM missions, the crew will be in no hurry to unload the supplies and equipment ferried aloft in the PMM. Robonaut 2, for example, is not expected to be activated for several months.

Over the next two days, the astronauts will enjoy a bit of off-duty time, participate in multiple interviews and a traditional joint crew news conference. At the end of flight day nine, the Discovery astronauts will move back aboard the shuttle, and hatches will be sealed in preparation for undocking the following day.

With Boe at the controls, Discovery is scheduled to pull away from the space station around 5:02 a.m. on flight day 10. After looping around the outpost for a photo-documentation inspection, the shuttle crew will depart and pull away before carrying out a final heat shield inspection to look for any signs of damage since the initial inspection the day after launch.

Assuming no problems are found, Lindsey and company will drop out of orbit on flight day 12 and return to the Kennedy Space Center. Discovery's 39th and final landing is expected around 9:59 a.m. on Nov. 14.

DISCOVERY WRAPS UP A DISTINGUISHED CAREER

"I don't think you can take a final voyage of a ship of exploration and not take some moments to celebrate its history," Barratt said. "As many people know, our ship Discovery, which is a ship of exploration, was named after several predecessor ships, all named Discovery, all ships of exploration.

"It's the culmination of a great heritage, really, and we hope there are future ships bearing that name. We will be carrying a medallion from the Royal Society that was struck in honor of Captain Cook. On Cook's third voyage, there was a ship called Discovery and that's the main ship for which our ship took its name. We'll be doing a few other taped commemoratives on it as well. But again, you cannot not celebrate the history and the heritage of this ship."

The contract authorizing construction of Discovery was awarded Jan. 29, 1979, and initial work to begin building the crew module began the following August. The spacecraft was completed at North American Rockwell's Palmdale, Calif., plant in October 1983 and was ferried to the Kennedy Space Center Nov. 9, 1983.

Following an on-pad main engine test firing June 2, 1984, NASA attempted to launch Discovery on its maiden voyage the following June 26. But in a moment of high drama, the shuttle's main engines shut down seconds after ignition because of a sluggish fuel valve.

The problem was corrected, and commander Henry Hartsfield and his crew, including Challenger astronaut Judith Resnik, finally blasted off Aug. 30, 1984, on a successful mission to deploy three commercial communications satellites and to test space station construction techniques.

Over the next 26 years and 38 flights, Discovery carried out four military missions, two Spacelab science flights, two visits to the Russian Mir space station, one Mir docking and 12 missions to the International Space Station. At least 24 civilian and military satellites were carried into space, including the Hubble Space Telescope.

Veteran of two on-pad launch aborts, Discovery also flew the return-to-flight missions following the 1986 destruction of the shuttle Challenger and the 2003 loss of Columbia. In addition, two stranded communications satellites were plucked out of orbit by spacewalking astronauts and brought back to Earth for repairs in November 1984 in what many veterans consider the most daring shuttle mission ever attempted.

Going into its final flight, Discovery had logged 142,917,535 miles traveled over 5,540 orbits, carrying 246 astronauts and cosmonauts into space, including former senator and Mercury astronaut John Glenn and Eileen Collins, the first woman to pilot and later command a space shuttle.

"When you really look at the space shuttle and its capability, it can do everything, everything you can think of in space except for one thing, it can't leave low-Earth orbit, but it can do everything else," Lindsey said in a NASA interview. "It can do robotics. It can do science. It can go dock. When you dock with the space station, in the end you have to maintain a three-inch corridor and one degree of attitude error and you can easily fly the shuttle manually and maintain that. I mean, that's unbelievable for a 120-ton vehicle.

"I don't think there's going to be another one that's ever going to match the versatility of the space shuttle, and I think that's the legacy. All the systems we've developed and things we've done on space station, or on space shuttle, have all had impacts in our society. I mean, literally any room you walk in, anything you do during the day, you can point at things in that room and say, 'That came out of the space program. This came from shuttle. This came from Apollo. This came from space station' and you can see it all around you.

"The public's not real aware of all of that ... and it's very hard to measure, but it's all there if you really think about it, and I think that's the legacy. I think the legacy is that all these things came out of it, and people take all of those things for granted."

NASA managers are considering a variety of options for Discovery's post-landing processing. Some have suggested maintaining the orbiter in a flight-ready state for as long as possible. Others have recommended using the orbiter for spare parts until Atlantis and Endeavour complete their final missions. Shannon favors a combination of approaches.

"We're in the middle of a very significant effort to identify hardware off of Discovery and also in the spares (inventory) that could be used for some future as yet unknown program, or that we would want to maintain as spares for Endeavour and Atlantis," Shannon said.

"We're also going to pull some off as engineering teaching units so that future generations will be able to take the hardware that was flown on the shuttle and dissect it and understand the engineering and how it was put together. We're also going to go in and look at some hardware on Discovery that has flown for 30 years that we've never looked at before. Things like actuators and some structural areas that are impossible to get to.

"Those will be fairly invasive, it will take time and it will take money," he said. "But I think that's one of the legacies the shuttle can provide. ... So even after Discovery lands, we will not be finished learning about the space environment. That's my goal, to start immediately on that."

No matter how the end game plays out, Discovery eventually will be shipped to a museum and put on display. But with nearly two dozen museums vying for one of NASA's three orbiters, it's not yet clear where Discovery will end up.

It has long been assumed that NASA's most veteran space shuttle would become part of the National Air and Space Museum's collection. But CollectSpace reported in a Nov. 1 article that the Smithsonian Institution may have problems coming up with the $28.8 million required to pay for preparations and shipment to Washington.

"Negotiations between NASA and the Smithsonian National Air and Space Museum are ongoing," said agency spokesman Mike Curie. "NASA will be making an announcement about the disposition of the shuttle orbiters, we expect, by the end of the year."

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CBS NEWS Coverage of Breaking Space News

11:15 AM, 10/31/10 Update: Engineers complete shuttle repairs, prepare to start countdown to launch Wednesday

By William HARWOOD
CBS News Space Consultant

Engineers have successfully repaired and retested new quick-disconnect fittings in the shuttle Discovery's right-side orbital maneuvering system rocket pod, clearing the way for the start of the ship's countdown Sunday and launch Wednesday on a two-spacewalk mission to deliver critical supplies, equipment and a final U.S. module to the International Space Station.

Discovery's countdown was scheduled to begin at 2 p.m. EDT (EDT=GMT-4), setting up a launch attempt at 3:52:13 p.m. Wednesday at roughly the moment Earth's eastward rotation carries pad 39A into the plane of the space station's orbit. It will be Discovery's 39th and final flight.

"So far, it's been a remarkable flow for Discovery," said NASA Test Director Steve Payne. "She's been an incredible vehicle and she caps a long and distinguished career with this particular flight. She's always amazed us with everything she can do and we expect this flight should be no different. We're looking forward to launch on Wednesday afternoon."

Forecasters are predicting a 70 percent chance of good weather Wednesday with just a chance of showers in the area, scattered clouds at 3,000 feet, broken decks at 9,000 and 25,000 feet and winds out of the north at 11 knots with gusts to 17. The odds drop to 60 percent "go" on Thursday because of an approaching frontal system. Forecasters also are keeping tabs on Hurricane Tomas, which is expected to take a turn to the northeast later in the week.

"We'll keep an eye on Tomas, but right now it doesn't look like it'll be a factor for launch," said shuttle weather officer Kathy Winters. "Our main concern will be if we have a delay . So right now on launch day we have a 30 percent chance of KSC weather prohibiting launch. If we happen to delay 24 hours, that's when a front will move into the area and we have more concerns. We'll keep watching that trend."

Depending on how the computer models play out, Winters said, "we may have to increase that 24-hour delay number."

Discovery's launch originally was planned for Monday, but the start of the countdown was delayed Friday after engineers discovered two leaking quick-disconnect fittings in an access panel where ground lines plug in to pressurize nitrogen and helium tanks in the ship's right-side OMS pod. Nitrogen is used to move various valves in the rocket pod while high-pressure helium in a much larger tank is used to push propellants to rocket engines used for orbital maneuvers.

NASA managers initially hoped to complete repairs and retest in time to start the countdown Saturday, setting up a Tuesday launching, but it quickly became apparent more time would be needed to complete the retest operation and to repressurize the high-pressure helium tanks. The latter is a 16-hour procedure that requires engineers to evacuate the launch pad.

In any case, the helium system was vented and replacement couplings were installed Saturday. Engineers then carried out extensive pressure checks and leak tests to make sure the problem had been resolved. The helium system was repressurized overnight Saturday.

"We completed early this morning our flight pressurization of our on-orbit control system tanks and the main propulsion tanks and it all went well," Payne said. "That is beyond us now."

As it turned out, the suspect nitrogen connector may have been healthy all along. During the repair work, engineers discovered the pressure in the ground supply line connected to the suspect fitting was higher than expected, possibly preventing a poppet in the quick-disconnect mechanism from closing. But the helium issue would have delayed launch regardless.

"Initially, we had two different issues with our quick disconnects, one with the nitrogen side and one with the helium side," Payne said. "The one that was the long pole, the one that took us a long time to resolve, was the one on the helium side because it required venting down our tanks and repressurizing. That just takes a long time because you have to do it slowly to allow the thermal conditioning to happen.

"For the nitrogen tank, it's a quick process. The tank is about the size of softball, it takes a couple of minutes to fill and empty. We thought it was the quick disconnect valve. There's a little poppet inside that's held open by pressure and when the pressure goes down it closes again. The (ground system) valve that was supposed to stop providing pressure to it was providing too much and it couldn't close properly. So we just went upstream and closed the gas off to that one so the pressure could bleed down and the QD could close. And it worked very well."

The primary goals of Discovery 's mission are to deliver a 21-foot-long cargo module loaded with supplies and equipment that will be used as a storage room to give station crews more room. Discovery's crew also will deliver an external cargo storage platform with a spare set of cooling system radiators. Two spacewalks are planned to facilitate the cargo module installation, to re-stow a failed ammonia pump module and to perform a variety of routine maintenance activities.

Assuming an on-time launch, Discovery will dock with the space station around 12:36 p.m. Friday. Two spacewalks are planned, on Nov. 7 and 9, with undocking on tap Nov. 12 at 5:02 a.m. and landing back at the Kennedy Space Center at 9:59 a.m. Nov. 14.

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CBS NEWS Coverage of Breaking Space News

By William HARWOOD
CBS News Space Consultant

NASA managers decided Saturday to delay the shuttle Discovery's launch an additional day to Wednesday to give engineers enough time to complete replacement and retest of leaky quick-disconnect fittings in the ship's right-side orbital maneuvering system rocket pod.

If all goes well, Discovery's countdown will begin at 2 p.m. EDT Sunday (EDT=GMT-4), setting up a launch attempt at 3:52:13 p.m. Wednesday, roughly the moment Earth's rotation carries launch pad 39A into the plane of the space station's orbit. The forecast calls for a 70 percent chance of acceptable weather Wednesday and Thursday, improving to 80 percent "go" on Friday.

NASA Test Director Jeffrey Spaulding said engineers are "really confident" they can finish the work in time to start the countdown Sunday.

"The team has done an excellent job overnight, it's been a lot of hard work," he said. "I think they've done a great job and I look forward to getting the call to stations tomorrow (to start the countdown)."

The primary goals of Discovery's 39th and final mission are to deliver a loaded cargo storage module to the International Space Station, along with a spare set of cooling system radiators that will be mounted on the lab's main power truss.

Assuming an on-time launch, Discovery would dock with the space station at 12:36 p.m. Friday. Two spacewalks are planned, on Nov. 7 and 9, with undocking on tap Nov. 12 at 5:02 a.m. and landing back at the Kennedy Space Center at 9:59 a.m. Nov. 14.

Launch had been targeted for Monday, but engineers ran into problems overnight Thursday with leaking nitrogen and helium quick-disconnect couplings used by Discovery's right-side OMS pod. The nitrogen gas is used to open and close a variety of valves while the helium is used to pressurize propellant tanks in the rocket pod.

Engineers decided early Friday to replace the fittings, delaying the start of Discovery's countdown to Saturday and pushing launch from Monday to Tuesday.

The repair work required engineers to vent high-pressure helium tanks in the OMS pod before swapping out the couplings. The replacement work was completed early Saturday and engineers began a series of leak tests to make sure the new fittings were tight before re-pressurizing the helium system.

Because the tanks were fully vented for the repair work, engineers had to first carry out an intermediate repressurization, a process expected to take about six hours to complete, followed by a 16-hour procedure to bring the system up to flight pressure.

To make a Tuesday launch target, NASA had to start Discovery's countdown by 2 p.m. (18:00 GMT) Saturday. But after a management review earlier Saturday, it was clear more time was needed and the decision was made to push the launch back one more day to Wednesday.

"The plan as we knew it yesterday was to vent down the tank and replace some parts we thought were faulty on an air-half coupling on our right-hand OMS maneuvering system pod and then do some leak checks," Spaulding said. "As we went through the day, we learned there was some additional work we needed to do ... from a leak check perspective and some of the venting operations that needed to be done.

"We did remove and replace the air-half coupling and the ground-half coupling that we talked about yesterday, the parts that were faulty, and we've done some initial leak checks on those and also some moisture samples. And all of those came back good."

Spaulding said engineers expect to complete the helium re-pressurization procedure early Sunday, well before the planned start of the countdown.

The shuttle's current launch period extends through Nov. 7. Spaulding said NASA managers planned to follow normal procedures, making two attempts in a row, if necessary, before standing down a day to give the launch team a chance to rest. Another two launch attempts then would be possible on Nov. 6 and 7 if necessary.

"Launching on Wednesday, we still have up to and including Sunday, so that gives us ... our normal four (launch attempts) in five-day capability we like to preserve," Spaulding said.

The next launch window opens Dec. 1.

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CBS NEWS Coverage of Breaking Space News

By William HARWOOD
CBS News Space Consultant

NASA managers decided Saturday to delay the shuttle Discovery's launch an additional day to Wednesday to give engineers enough time to complete repairs and retest of leaky quick-disconnect fittings in the ship's right-side orbital maneuvering system rocket pod.

Liftoff on a space station resupply mission is now targeted for 3:52:13 p.m. EDT (19:52:13 GMT) Wednesday at roughly the moment Earth's rotation carries launch pad 39A into the plane of the space station's orbit. The forecast calls for a 70 percent chance of acceptable weather.

Launch had been targeted for Monday, but engineers ran into problems overnight Thursday with leaking nitrogen and helium quick-disconnect couplings used by Discovery's right-side OMS pod. The nitrogen gas is used to open and close a variety of valves while the helium is used to pressurize propellant tanks in the rocket pod.

Engineers decided early Friday to replace the fittings, delaying the start of Discovery's countdown to Saturday and pushing launch from Monday to Tuesday.

The repair work required engineers to vent high-pressure helium tanks in the OMS pod before swapping out the couplings. The replacement work was completed early Saturday and engineers began a series of leak tests to make sure the new fittings are tight. Re-pressurizing the helium system -- an operation that takes 16 hours and requires the launch pad to be evacuated -- was scheduled to begin at 2 p.m.

That's when engineers had hoped to restart Discovery's countdown for a Tuesday launch attempt. But after a management review early Saturday, it was clear more time was needed and the decision was made to push the launch back one more day to Wednesday. The shuttle's current launch period extends through Nov. 7. The next launch period opens Dec. 1.

This status report will be/10 Updated after a 10 a.m. EDT (14:00 GMT) status briefing.

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CBS NEWS Coverage of Breaking Space News

7:15 AM, 10/30/10 Update: Suspect hardware replaced; management review on tap

By William HARWOOD
CBS News Space Consultant

Suspect quick-disconnect hardware in the shuttle Discovery's right side orbital maneuvering system rocket pod has been replaced, engineers reported early Saturday. If all goes well, high-pressure helium re-pressurization, a 16-hour procedure, will begin at 2 p.m. (18:00 GMT).

Discovery's countdown to a day-late Tuesday launch also is scheduled to pick up at 2 p.m., setting up a launch attempt at 4:17:56 p.m. (20:17:56 GMT) Tuesday. But the helium re-pressurization process requires personnel to clear the launch pad and it's not yet known how that might impact a countdown.

Late Friday, engineers said a Tuesday launch was in doubt, but senior managers decided to assess the progress of repairs early today before making a decision on whether to start the countdown or delay the launch one more day to Wednesday at 3:52:13 p.m. (19:52:13 GMT).

The primary goals of Discovery's mission, the orbiter's 39th and final flight, are to deliver a loaded cargo module and a spare set of cooling system radiators to the International Space Station.

Launch originally was targeted for Monday, but the flight was delayed at least one day to Tuesday when engineers discovered leaks on the shuttle side of nitrogen and helium couplings where pressurization lines attach to the shuttle's right-side OMS pod.

Nitrogen is used to drive valves in the rocket pod while helium is used to pressurize the main propellant tanks. Leaky seals in the couplings have been seen before and repairs are not considered out of the ordinary. But the time required for re-testing and re-pressurization could be an issue.

NASA managers planned to meet at 8 a.m. (12:00 GMT) to review the progress of repairs, followed by a news briefing at 10 a.m. (14:00 GMT). This status report will be/10 Updated as information becomes available.

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CBS NEWS Coverage of Breaking Space News

12:30 PM, 10/29/10 Update: NASA managers optimistic about shuttle repair work, Tuesday launch

By William HARWOOD
CBS News Space Consultant

The shuttle Discovery's launch on a space station resupply mission is being delayed from Monday to at least Tuesday -- election day in the United States -- to give engineers time to repair two leaking quick-disconnect fittings in pressurization systems used by the ship's right-side orbital maneuvering system rocket pod.

NASA Test Director Jeffrey Spaulding said the repair work is not complicated but it will require engineers to vent and then repressurize high-pressure helium gas in the OMS system, work that requires launch personnel to clear the pad.

As a result, the start of Discovery's countdown will be delayed one day, from Friday afternoon to 2 p.m. EDT (18:00 GMT) Saturday. Assuming the repair work goes well, launch will be re-targeted for 4:17:56 p.m. (20:17:56 GMT) Tuesday. Forecasters are predicting a 70 percent chance of acceptable weather Tuesday, Wednesday and Thursday.

Discovery's crew -- commander Steven Lindsey, pilot Eric Boe, Nicole Stott, Michael Barratt and spacewalkers Timothy Kopra and Alvin Drew -- flew to the Kennedy Space Center Thursday to prepare for launch. They will use the extra day to relax and review their flight plan.

Assuming an on-time launch Tuesday, Lindsey will guide Discovery to a docking with the International Space Station around 12:11 p.m. ( 16:11 GMT) Thursday, Nov. 4. Two spacewalks are planned Nov. 6 and 8 amid work to attach a cargo storage module and an external spare parts platform. Undocking would be expected around 6:05 a.m. (10:05 GMT) Nov. 11 with landing back at the Kennedy Space Center around 11:05 a.m. on Nov. 13.

Lindsey said last week the astronauts voted early, expecting to be off the planet Tuesday or, if delayed, in a launch countdown. With early voting allowed through Saturday in Florida, Spaulding said NASA managers have been encouraging the launch team to vote early as well because of the possibility of a launch delay. But he said NASA plans to press ahead with a launching Tuesday, if possible, regardless of the election.

"That was something we recognized a long time ago, the possibility for the dates to line up," he said. "We did encourage the team, we did throughout the entire pad flow, to take advantage of early voting, absentee voting, because we certainly want to give everybody the opportunity to get out and (vote)."

The OMS pod pressurization problem cropped up overnight during work to prepare Discovery for the start of its launch countdown.

A leak was first noticed in a quick-disconnect fitting used to load nitrogen gas into the right-side orbital maneuvering system rocket pod to drive valves and to pressurize smaller propellant tanks. Engineers later discovered a helium leak in another quick-disconnect fitting where ground supply lines attach to the right OMS pod. High pressure helium is used to pressurize the main propellant tanks in the rocket pod.

"While we were doing our pressurization last night, our right-hand orbital maneuvering system helium tank vented down unexpectedly when we were venting the ground side ... which indicated we had an issue with our flight-side coupling between those two quick disconnects that allow gases to flow back and forth," Spaulding said.

"We did attempt to do some troubleshooting, repairs on that. They were unsuccessful. When we took the flight side off, we did notice there was part of a seal, an O-ring, in there, it looked like it came from the ground side. We did remove that and attempted to remate the disconnects and the couplings and we still were unsuccessful with the repairs."

After engineering meetings to discuss repair options, the team decided to replace the couplings on both sides of the interface. In preparation for the repair work, the helium tanks were vented. After the new components are in place, leak checks will be carried out followed by re-pressurization of the helium tanks.

"The big part of that whole process is the actual repressurization of those tanks, which is about two shifts, or 16 hours of work," Spaulding said. "The actual repairs, removal and replacement of those parts, isn't very complicated and we've done it in the past. ... It's a well known process and the folks do a very good job with that.

"But that's kind of the thing that's driving us, the need to depressurize our tanks and then repressurize them. That repressurization of the tanks requires a pad clear, which precludes us from doing the normal things we would do during a normal countdown. ... That's why we made the decision to push off 24 hours for the start of our countdown and subsequently the launch date as well."

The right-side OMS pod was re-installed in July after work to fix a helium isolation valve that had problems during Discovery's most recent mission in April. A leak in a fuel crossfeed line associated with the right OMS pod was repaired last weekend when two internal seals were replaced.

Spaulding said the current leaks are not related to last weekend's repair work or the rocket pod's removal and reinstallation.

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CBS NEWS Coverage of Breaking Space News

By William HARWOOD
CBS News Space Consultant

KENNEDY SPACE CENTER, Fla.--NASA managers decided early Friday to delay launch of the shuttle Discovery from Monday to at least Tuesday -- election day in the United States -- because of work to fix two leaks, one helium and one nitrogen, in the plumbing of the orbiter's right-side orbital maneuvering system rocket pod.

The start of Discovery's countdown will slip one day to 2 p.m. EDT (18:00 GMT) Saturday. Assuming the repair work goes smoothly, the shuttle could be ready for launch by Tuesday, at 4:17:56 p.m. (20:17:56 GMT), but that remains to be seen. The current launch window extends through Nov. 7.

"This is not a huge deal, but we just have no cushion in the schedule," a NASA official said earlier today.

Two interim problem reports, or IPRs, were written up overnight, one because of a gaseous nitrogen leak at a quick disconnect fitting and another in the helium pressurization system that is used to push propellants into the OMS pod engines.

The first problem showed up during a gaseous nitrogen fill valve leak check and the second issue was discovered after the helium system was pressurized for launch. An inspection revealed an internal O-ring in a ground-system helium coupling was partially stuck inside its shuttle counterpart. That fitting apparently will have to be replaced.

The right-side OMS pod was re-installed in July after work to fix a helium isolation valve that had problems during Discovery's most recent mission in April. A leak in a fuel crossfeed line associated with the right OMS pod was repaired last weekend when two internal seals were replaced.

NASA officials say the current leaks are not related to last weekend's repair work or the rocket pod's removal and reinstallation. This status report will be/10 Updated after a countdown status briefing at 10 a.m. EDT (14:00 GMT).

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CBS NEWS Coverage of Breaking Space News

815a 10/29/10 Update: Engineers troubleshoot nitrogen, helium leaks in shuttle rocket pod

By William HARWOOD
CBS News Space Consultant

Engineers are troubleshooting two leaks, one helium and one nitrogen, in the plumbing of the shuttle Discovery's right-side orbital maneuvering system rocket pod.

Discovery's countdown to launch on a space station resupply mission is scheduled to begin at 3 p.m. today. Liftoff on the shuttle's 39th and final mission is targeted for 4:40:27 p.m. EDT (20:40:27 GMT) Monday. The current launch window extends through Nov. 7.

It is not yet known what impact, if any, the two leaks might have on the countdown or launch. An engineering report said both are "under review" and engineers are meeting this morning to discuss repair options.

"This is not a huge deal, but we just have no cushion in the schedule," said a NASA official.

Two interim problem reports, or IPRs, were written up overnight, one because of a gaseous nitrogen leak at a quick disconnect fitting and another in the helium pressurization system that is used to push propellants into the OMS pod engines.

The first problem showed up during a gaseous nitrogen fill valve leak check and the second issue was discovered after the helium system was pressurized for launch. An inspection revealed an internal O-ring in a ground-system helium coupling was partially stuck inside its shuttle counterpart. That fitting apparently will have to be replaced.

The right-side OMS pod was re-installed in July after work to fix a helium isolation valve that had problems during Discovery's most recent mission in May. A leak in a fuel crossfeed line associated with the right OMS pod was repaired last weekend when two internal seals were replaced.

It is not yet known whether the helium and nitrogen leaks could be related to last weekend's repair work or the rocket pod's removal and reinstallation. This status report will be/10 Updated after a countdown status briefing at 10 a.m. EDT (14:00 GMT).

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CBS NEWS Coverage of Breaking Space News

6p 10/28/10 Update: Discovery astronauts fly to Florida to prepare for Monday launch

By William HARWOOD
CBS News Space Consultant

The six-member all-veteran crew of the shuttle Discovery flew to Florida Thursday to await the start of their countdown Friday and blastoff Monday on a space station resupply mission.

Arriving at the Florida spaceport after staggered flights from Houston aboard T-38 jets, commander Steven Lindsey, pilot Eric Boe, Nicole Stott, Michael Barratt and spacewalkers Timothy Kopra and Alvin Drew touched down between 2:53 p.m. EDT and 4 p.m. (18:53 and 20:00 GMT).

"Weather permitting, if all goes well, we'll have a nice Nov. 1 on-time launch," Lindsey told reporters at the Shuttle Landing Facility. "We're looking forward to it."

Discovery's countdown to launch on the orbiter's 39th and final mission is scheduled to begin at 3 p.m. (19:00 GMT) Friday. Liftoff from pad 39A is targeted for 4:40:27 p.m. (20:40:27 GMT) Monday, roughly the moment Earth's rotation carries the pad into the plane of the space station's orbit.

"We were able to talk to our friends on the space station this morning and they have spent a lot of time getting everything ready up there for us," Barratt said. "We have a huge collection of hardware up there and I think we'll exceed a million pounds for the first time during our docked mission. We just want to give a nod to the program office that put the space station together and runs it. We're really looking forward to getting up there and doing our part to add to it yet again."

The primary goals of the flight are to deliver a 21-foot-long cargo storage module, the last pressurized compartment NASA plans to launch to the station. The permanent multi-purpose logistics module, or PMM, is loaded with 6,536 pounds of cargo, including an experimental humanoid robot known as Robonaut 2.

Another 1,500 pounds of supplies and equipment are mounted in the shuttle's crew cabin, and an external storage platform carrying a spare set of folding radiator panels is mounted in the ship's cargo bay. The 8,161-pound storage platform and the radiator panels will be mounted on the space station's power truss.

"It's really great to be back here, this place brings smiles to all of our faces for sure," said Stott. "We're bringing up some pretty cool stuff. We've got a permanent logistics module that we'll be attaching and we have the ELC-4, which is basically an external carrier that will have some large spare parts for the station. So we really look forward to being able to put the station in the best possible configuration for future missions."

Discovery's launch window extends through Nov. 7. If the shuttle is not off the ground by then, the next launch window will open Dec. 1.

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CBS NEWS Coverage of Breaking Space News

By William HARWOOD
CBS News Space Consultant

After reviewing normal processing and weekend work to fix a small fuel leak, NASA managers Monday cleared the shuttle Discovery for an election-eve launch Nov. 1 to begin a 12-day space station resupply mission, the orbiter's 39th and final flight.

Testing indicates new seals in a suspect flange are properly seated and holding pressure with no signs of additional seepage. Assuming no other problems develop, engineers believe they will be ready to start Discovery's countdown at 3 p.m. (19:00 GMT) Friday, setting up a launch attempt at 4:40:26 p.m. EDT (20:40:26 GMT) Monday.

"We're in great shape out at the pad," Launch Director Michael Leinbach told reporters. "We've used up our four days of contingency for that leak repair, but we're right on schedule now. ... I see no reason right now at all that we can't get into the launch countdown per plan on Friday afternoon."

Discovery's all-veteran crew -- commander Steven Lindsey, pilot Eric Boe, Nicole Stott, Michael Barratt and spacewalkers Timothy Kopra and Alvin Drew -- plans to fly to the Kennedy Space Center from Houston on Thursday to prepare for flight.

The primary goals of the 133rd shuttle mission are to deliver and install a final U.S. pressurized module loaded with equipment and supplies, to mount a spare radiator panel on the station's power truss, to deliver an experimental robot and to stage two spacewalks to carry out a variety of assembly and maintenance tasks.

The mission comes just shy of the 12th anniversary of the start of station construction Nov. 20, 1998, and the 10th anniversary of the first crew's arrival on Nov. 2, 2000. On Monday, yet another milestone was achieved as the international lab complex, continuously manned for 3,644 days, eclipsed the previous record set by the Russian Mir space station.

Assuming an on-time launch, Lindsey plans to guide Discovery to its 13th and final ISS docking around 1:18 p.m. (17:18 GMT) Nov. 3. The first spacewalk will get underway at 10:35 a.m. (14:35 GMT) on Nov. 5 and the permanent multi-purpose module, or PMM, will be attached to the central Unity module's Earth-facing port the next day.

"It's pretty exciting that Discovery is going to take up the last major United States module to the station,' shuttle Program Manager John Shannon said last week. "We're making good on our promise that we would get the space station in the absolute best possible config we could with spares and equipment before we retire the space shuttle."

Kopra and Drew plan a second spacewalk on Nov. 7. If all goes well, Discovery will undock from the station around 5:40 a.m. (10:40 GMT) on Nov. 10, setting up a landing back at the Kennedy Space Center around 10:38 a.m. (15:38 GMT) on Nov. 12.

Senior NASA managers attended an all-day executive-level flight readiness review Monday at the Kennedy Space Center and formally cleared Discovery for launch Nov. 1. The window extends through Nov. 7. The next shuttle launch window opens Dec. 1.

Last week, NASA managers ordered the replacement of two internal seals in a fuel-line flange in the plumbing of Discovery's orbital maneuvering system rocket pods that had shown signs of a small leak of toxic monomethyl hydrazine rocket fuel.

The leak appeared to stop during torque checks of the six bolts holding the flange together, but because of the volatile nature of the fuel, shuttle integration manager Mike Moses ordered the seals replaced to return the flange to a known pristine state.

Working through the weekend, engineers drained propellants from the OMS pod system, vacuum-dried the lines, took the flange apart and replaced the two internal seals. After reassembling the flange, the OMS pod propellant tanks were reloaded Sunday. Subsequent tests showed the flange was tight with no signs of any seepage.

"It was a very, very tough job," Leinbach said of the repair work. "Our technicians really came through with flying colors, It was an outstanding job."

As for what caused the leak in the first place, there were no obvious signs of damage to the seals or the flange mating surfaces. Leinbach said engineers suspect "transient contamination" might be the culprit.

There were no other issues of any significance. Shuttle integration manager Mike Moses said engineers discussed erosion damage seen in the nozzle of a five-segment booster test fired in Utah in late August. But the shuttle boosters use four segments and a different nozzle design. No such damage has ever been seen in a shuttle booster and NASA managers cleared Discovery's twin SRBs for launch.

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CBS NEWS Coverage of Breaking Space News

1:55 PM, 10/25/10 Update: Discovery cleared for Nov. 1 launch

By William HARWOOD
CBS News Space Consultant

After reviewing normal processing and weekend work to fix a small fuel leak, NASA managers Monday cleared the shuttle Discovery for an election-eve launch Nov. 1 to begin a 12-day space station resupply mission, the orbiter's 39th and final flight.

Testing indicates new seals in a suspect flange are properly seated and holding pressure with no signs of additional seepage. Assuming no other problems develop, engineers believe they will be ready to start Discovery's countdown at 3 p.m. Friday, setting up a launch attempt at 4:40:26 p.m. EDT (20:40:26 GMT) next Monday.

A detailed/10 Update will be posted here after a 4 p.m. news conference with senior NASA managers.

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CBS NEWS Coverage of Breaking Space News

10:10 PM, 10/23/10 Update: Seals replaced in shuttle fuel line flange

By William HARWOOD
CBS News Space Consultant

Working through the weekend, engineers drained toxic propellants from the shuttle Discovery's orbital maneuvering system rocket pods, dried out the lines, disassembled a fuel-line flange Saturday and replaced two internal seals in a bid to stop an on-again, off-again leak.

The seal replacement work was completed just after 7 p.m. EDT Saturday (23:00 GMT). After reassembling the flange, engineers planned to begin reloading rocket fuel starting at 3 a.m. (07:00 GMT) Sunday.

Senior NASA managers plan to attend an executive-level flight readiness review Monday to assess the repair work and normal launch processing. Assuming no problems are found, engineers will press ahead with work to ready Discovery for the start of its countdown at 3 p.m. (19:00 GMT) Friday, setting up a launch attempt at 4:40 p.m. (20:40 GMT) Monday, Nov. 1, to kick off a space station resupply mission.

Seepage of monomethyl hydrazine, or MMH, rocket fuel was discovered earlier at a crossfeed flange in the propellant plumbing of the shuttle's right-side orbital maneuvering system rocket pod.

The shuttle is equipped with two such rocket pods, one on either side of the ship's vertical tail fin, that burn monomethyl hydrazine with an oxidizer, nitrogen tetroxide, to carry out maneuvers in orbit. Crossfeed lines in the shuttle's aft engine compartment allow propellants to be moved from one pod to the other.

During torque checks to verify six bolts in the flange had been properly tightened, the leak disappeared. But without a clear understanding of what caused the leak in the first place, NASA managers decided to replace two internal seals and return the flange to a known pristine condition.

At the time the decision was made, Discovery still had four days of contingency time in its processing schedule. Engineers say the remaining timeline is tight, but Discovery should stay on schedule if leak tests confirm the seal replacement worked and no other major problems develop.

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CBS NEWS Coverage of Breaking Space News

01:45 PM, 10/21/10 Update: NASA managers optimistic seal replacement will fix shuttle leak

By William HARWOOD
CBS News Space Consultant

Engineers geared up Thursday to drain toxic rocket fuel from the shuttle Discovery's orbital maneuvering system rocket pods before beginning weekend work to replace suspect seals in a fuel-line flange to fix an on-again off-again leak. Engineers say the schedule is tight, but they believe they can complete repairs in time for Discovery's planned Nov. 1 launch on a space station resupply mission.

"We did some troubleshooting on it, it looked like the leak stopped," shuttle Program Manager John Shannon told reporters Thursday. "But the tenet that we have is we fly with accepted risk, we don't fly with unknown risk. And I characterize this as an unknown risk case because we didn't understand why we had that small leak."

Discovery's countdown is scheduled to begin at 3 p.m. EDT (19:00 GMT) on Oct. 29, setting up a launch attempt at 4:40 p.m. (20:40 GMT) on Nov. 1. Along with monitoring the repair work and normal processing at pad 39A, NASA managers also are keeping close tabs on Tropical Storm Richard, which some computer models predict will pass through the spaceport area before moving out into the Atlantic Ocean.

Seepage of monomethyl hydrazine, or MMH, fuel was discovered last week at a crossfeed flange in the propellant plumbing of the shuttle's right-side orbital maneuvering system rocket pod.

The shuttle is equipped with two such rocket pods, one on either side of the ship's vertical tail fin, that burn monomethyl hydrazine with an oxidizer, nitrogen tetroxide, to carry out maneuvers in orbit. Crossfeed lines in the shuttle's aft engine compartment allow propellants to be moved from one pod to the other.

The leak stopped during inspections to make sure six flange bolts were properly tightened, possibly the result of increased pressure in the line causing an internal seal to properly seat.

But shuttle integration manager Mike Moses, uncomfortable with the on-again, off-again nature of the leak, decided to forego additional tests and inspections and ordered engineers to replace two internal seals to put the flange back in pristine condition.

Because of the toxic nature of the propellants, replacing the seals requires launch pad personnel to clear the area during the fuel-draining process, interrupting normal processing. Engineers planned to begin draining the tanks Thursday afternoon.

Once the lines are confirmed dry, technicians wearing bulky protective pressure suits will open up the flange, inspect the sealing surfaces, polish them if necessary, install new seals and put the assembly back together.

"The team is working very hard right now to set up all the equipment to drain the tanks, they'll do what they call educting, basically take it down to (vacuum), get it all safe," Shannon said. "Then we'll break that flange open and look at the metal sealing surfaces, look at the two sealing rings. They're like O-rings, metal covered with Teflon inside there. We'll understand the situation and I fully believe the team will get that back together this weekend and we'll be in good shape to go fly."

If the seal replacement does not resolve the problem, Discovery's launching almost certainly would be delayed.

"If there is some other problem or significant flange damage, or if we damage it somehow in trying to repair it, then we would lay that schedule out (for repairs)," Shannon said. "But we have not done that work yet."

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CBS NEWS Coverage of Breaking Space News

By William HARWOOD
CBS News Space Consultant

Uncomfortable with an on-again, off-again leak in the plumbing used by the shuttle Discovery's maneuvering rockets, NASA managers Tuesday ordered engineers to forego additional testing and to press ahead instead with work to replace internal seals in a fuel line fitting.

Because the propellants are toxic, engineers will have to close launch pad 39A for normal work before draining the shuttle's orbital maneuvering system tanks and lines. After replacing seals in the fuel line flange where a small leak was observed over the weekend, the tanks will be refilled and additional tests will be carried out to make sure the fitting is tight and able to withstand the vibrations and pressures of launch.

Discovery's liftoff on a space station resupply mission is targeted for Nov. 1. The repair work is expected to take seven days to complete, but with four days of contingency time left in the shuttle's processing schedule, NASA managers believe the seals can be replaced in parallel with other work without impacting launch. If more invasive repairs are required, launch almost certainly would be delayed.

The trouble involves seepage of monomethyl hydrazine, or MMH, fuel at a crossfeed flange in the propellant plumbing of the shuttle's right-side orbital maneuvering system rocket pod. The shuttle is equipped with two such rocket pods, one on either side of the ship's vertical tail fin, that burn monomethyl hydrazine with an oxidizer, nitrogen tetroxide, to carry out maneuvers in orbit. Crossfeed lines in the shuttle's aft engine compartment allow propellants to be moved from one pod to the other.

Engineers suspected a leak last week. After testing over the weekend, they were able to trace the leak to a specific area of a flange in the crossfeed system where two sections of propellant line come together. But it is not yet clear whether the seepage was the result of trouble with seals in the flange or the flange itself.

The right-side OMS pod was removed after Discovery's most recent flight in April to repair a helium isolation valve in another part of the system. After the pod was re-installed in July, leak checks were normal and no obvious loss of pressure has been noted. But insulation around the flange was found to be damp with MMH over the weekend.

Overnight Monday, engineers checked the tightness of the six bolts holding the flange together and none of the bolts moved, indicating they were properly torqued. At the same time, the temperature of the system was changed, resulting in increased pressure in the fuel line. Subsequent measurements found no more traces of leakage.

"That's not the scenario they anticipated," a NASA official said.

The flange features two internal seals and it is possible the increased pressure helped seat one or both. Engineers developed a plan to pump helium into a test port Tuesday to pressurize the volume between the primary and secondary seals to look for any signs of additional leakage. Troubleshooters also considered pressurizing the line to flight levels of around 250 pounds per square inch to make sure the seals are properly seated and secure.

But given the toxic nature of MMH and the lack of a clear explanation for what started and stopped the leak, shuttle integration manager Mike Moses decided late Tuesday to replace the seals to make sure the problem is resolved. The replacement work was expected to get underway Wednesday.

Discovery is scheduled for launch on a space station resupply mission at 4:40 p.m. EDT (20:40 GMT) on Nov. 1. The launch window originally was expected to close on Nov. 5, but it later was extended to Nov. 6 and more recently, Nov. 7. If Discovery is not off the ground by then, the flight will be delayed at least to early December because of conflicts with other launches, already planned space station spacewalks and temperature restrictions due to the station's orbit.

Senior NASA managers plan to attend an executive-level flight readiness review at the Kennedy Space Center next Monday to review ground processing and to set an official launch date./10 Updates will be posted here as warranted.

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CBS NEWS Coverage of Breaking Space News

By William HARWOOD
CBS News Space Consultant

A small fuel leak in the plumbing used by the shuttle Discovery's maneuvering rockets apparently stopped during work overnight to double-check the torque on six bolts in a suspect flange. There were no obvious problems with the bolts and it's possible increased pressure in the line may have helped seat internal seals.

But officials said engineers planned additional tests to make sure the system is safe for launch Nov. 1 or whether more invasive repairs might be needed.

"Just because the leak went away doesn't mean it will stay away," a NASA official said.

The trouble involves seepage of toxic monomethyl hydrazine, or MMH, fuel at a crossfeed flange in the propellant plumbing of the shuttle's right-side orbital maneuvering system rocket pod. The shuttle is equipped with two such rocket pods, one on either side of the ship's vertical tail fin, that burn monomethyl hydrazine with an oxidizer, nitrogen tetroxide, to carry out maneuvers in orbit. Crossfeed lines in the shuttle's aft engine compartment allow propellants to be moved from one pod to the other.

After testing over the weekend, engineers were able to trace the leak to a specific area of a large flange in the crossfeed system where two sections of propellant line come together. But it is not yet clear whether the seepage was the result of trouble with seals in the flange or the flange itself.

The right-side OMS pod was removed after Discovery's most recent flight in April to repair a helium isolation valve in another part of the system. After the pod was re-installed in July, leak checks were normal and no obvious loss of pressure has been noted. But insulation around the flange was found to be damp with MMH over the weekend.

Overnight Monday, engineers checked the torque, or tightness, of the six bolts holding the flange together and none of the bolts moved, indicating they were properly torqued. At the same time, the temperature of the system was changed, resulting in increased pressure in the fuel line. Subsequent measurements found no more traces of leakage.

"That's not the scenario they anticipated," the official said.

The flange features two internal seals and it is possible the increased pressure helped seat one or both seat properly. In any case, engineers planned to pump helium into a test port Tuesday to pressurize the volume between the primary and secondary seals to look for any signs of additional leakage. Troubleshooters also may pressurize the line to flight levels of around 250 pounds per square inch to make sure the seals are properly seated and secure.

The propellants are extremely toxic and it is unlikely NASA would launch a shuttle with a known leak, however small. If problems persist, engineers could be forced to drain the propellants and replace one or both seals in the flange, work that would interrupt normal launch processing for two to three days. Replacing the flange itself at the launch pad would be much more difficult.

Discovery is scheduled for launch on a space station resupply mission at 4:40 p.m. EDT (20:40 GMT) on Nov. 1. If the shuttle is not off the pad by Nov. 5 or 6, the flight will be delayed at least to early December because of conflicts with other launches, already planned space station spacewalks and temperature restrictions due to the station's orbit.

Senior NASA managers plan to attend an executive-level flight readiness review at the Kennedy Space Center next Monday to review ground processing and to set an official launch date./10 Updates will be posted here as warranted.

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CBS NEWS Coverage of Breaking Space News

By William HARWOOD
CBS News Space Consultant

Engineers troubleshooting a small fuel leak aboard the shuttle Discovery decided Monday to carry out additional tests before more invasive and time-consuming work to replace a suspect seal, officials said.

After an afternoon review, troubleshooters were asked to double-check the torque on six bolts around a presumably leaky flange fitting and tighten if necessary. If subsequent leak tests show no more signs of seepage, a NASA spokeswoman said, Discovery could be cleared for launch as is.

Otherwise, engineers likely will be forced to evacuate launch pad 39A and drain the on-board propellants Wednesday before work to change out a suspect seal. NASA officials say enough contingency time remains in the processing schedule to complete the work in time for launch Nov. 1 as planned if no major problems are encountered.

The trouble involves seepage of toxic monomethyl hydrazine, or MMH, fuel at a crossfeed flange in the propellant plumbing of the shuttle's right-side orbital maneuvering system rocket pod. The shuttle is equipped with two such rocket pods, one on either side of the ship's vertical tail fin, that burn monomethyl hydrazine with an oxidizer, nitrogen tetroxide, to carry out maneuvers in orbit.

After testing over the weekend, engineers were able to trace the leak to a specific area of a large flange where two sections of propellant line come together. But it is not yet clear whether the seepage involves a loose bolt, a seal in the flange or the flange itself.

The right-side OMS pod was removed after Discovery's most recent flight in April to repair a helium isolation valve in another part of the system. After the pod was re-installed in July, leak checks were normal and no obvious loss of pressure has been noted. But insulation around the flange was found to be damp with MMH over the weekend.

Because the propellants are extremely toxic, the OMS pod tanks must be emptied and the propellant lines drained before any invasive repair work.

With Discovery in the vertical orientation at the launch pad, removing residual propellant from the lines is expected to be difficult. Even so, engineers believe they can replace the seal, if necessary, and reload the system in time to make the current launch date. Replacing the flange itself at the pad would be much more difficult, engineers say, requiring lines to be cut and welded.

As of Monday, the launch processing schedule included four days of contingency time to handle unexpected problems.

Discovery is scheduled for launch on a space station resupply mission at 4:40 p.m. EDT (20:40 GMT) on Nov. 1. If the shuttle is not off the pad by Nov. 5 or 6, the flight will be delayed at least to early December because of conflicts with other launches, already planned space station spacewalks and temperature restrictions due to the station's orbit.

Senior NASA managers plan to attend an executive-level flight readiness review at the Kennedy Space Center next Monday to review ground processing and to set an official launch date./10 Updates will be posted here as warranted.

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CBS NEWS Coverage of Breaking Space News

12:25 PM, 10/18/10 Update: Engineers troubleshoot small maneuvering system fuel leak aboard shuttle Discovery

By William HARWOOD
CBS News Space Consultant

Engineers are troubleshooting a small fuel leak aboard the shuttle Discovery that will require them to interrupt launch processing and drain toxic propellants from the ship's aft rocket pods before beginning repair work later this week.

The operation will close launch pad 39A for normal operations for two to three days, but NASA officials say enough contingency time remains in the processing schedule to complete the work in time for launch Nov. 1 as planned if no major problems are encountered.

The trouble involves seepage of toxic monomethyl hydrazine, or MMH, fuel at a crossfeed flange in the propellant plumbing of the shuttle's right-side orbital maneuvering system rocket pod. The shuttle is equipped with two such rocket pods, one on either side of the ship's vertical tail fin, that burn monomethyl hydrazine with an oxidizer, nitrogen tetroxide, to carry out maneuvers in orbit.

After testing over the weekend, engineers were able to trace the leak to a specific area of a large flange where two sections of propellant line come together. But it is not yet clear whether the seepage involves a seal in the flange or the flange itself.

The right-side OMS pod was removed after Discovery's most recent flight in April to repair a helium isolation valve in another part of the system. After the pod was re-installed in July, leak checks were normal and no obvious loss of pressure has been noted. But insulation around the flange was found to be damp with MMH over the weekend.

Because the propellants are extremely toxic, repairs cannot begin until the OMS pod tanks are emptied and the propellant lines drained. The going-in plan is to drain the tanks and lines Wednesday and then to replace the seal.

With Discovery in the vertical orientation at the launch pad, removing residual propellant from the lines is expected to be difficult. Even so, engineers believe they can replace the seal and reload the system in time to make the current launch date. Replacing the flange itself at the pad would be much more difficult, engineers say, requiring lines to be cut and welded.

As of Monday, the launch processing schedule included four days of contingency time to handle unexpected problems.

Discovery is scheduled for launch on a space station resupply mission at 4:40 p.m. EDT (20:40 GMT) on Nov. 1. If the shuttle is not off the pad by Nov. 5 or 6, the flight will be delayed at least to early December because of conflicts with other launches, already planned space station spacewalks and temperature restrictions due to the station's orbit.

Senior NASA managers plan to attend an executive-level flight readiness review at the Kennedy Space Center on Tuesday to review ground processing and to set an official launch date./10 Updates will be posted here as warranted.

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CBS NEWS Coverage of Breaking Space News

2:00 PM, 10/15/10 Update: Discovery astronauts strap in for practice countdown

By William HARWOOD
CBS News Space Consultant

The shuttle Discovery's six-member crew worked through a dress-rehearsal countdown aboard the shuttle Discovery Friday, setting the stage for launch Nov. 1 on a space station assembly mission. It will be Discovery's 39th and final flight.

"It's bittersweet, you've probably heard that a lot," commander Steven Lindsey told reporters at the launch pad Thursday. "Discovery's a workhorse, the fleet leader in number of flights, done a lot of famous flights, all the return-to-flight test missions. Yet when you walk inside Discovery, it still looks like a new car even after almost 30 years of service. It's a great machine, a great vehicle.

"For us, it's a privilege to be able to fly that last flight on Discovery but it's also sad because after that, it's retired. I just hope that when it goes to the Smithsonian (Air and Space Museum) that it's laid out in a way such that the public can actually go through it and see and get a feeling for what it was really like to fly it. That's something that'll always be in our memories."

Wearing bright orange pressure suits, Lindsey, pilot Eric Boe, Michael Barratt, Nicole Stott and spacewalkers Timothy Kopra and Al Drew began strapping in shortly before 8:30 a.m. EDT (12:30 GMT) for the final two-and-a-half hours of a simulated countdown. All six astronauts are spaceflight veterans and three of them -- Barratt, Kopra and Stott -- have logged long-duration flights aboard the space station.

Earlier this week, the astronauts reviewed launch pad emergency procedures, all part of a traditional three-day terminal countdown demonstration test, or TCDT. Lindsey and his crewmates planned to fly back to the Johnson Space Center in Houston Friday afternoon for final preparations. If all goes well, they will return to Florida Oct. 28, the day before their countdown begins.

Discovery's processing has proceeded smoothly since roll out to pad 39A Sept. 21. Senior NASA managers plan to attend an executive-level flight readiness review Tuesday to set an official launch date. As of this writing, Discovery is targeted for liftoff at 4:40:20 p.m. (20:40:20 GMT) Nov. 1, roughly the moment Earth's rotation carries the launch pad into the plane of the space station's orbit.

The primary goals of the 133rd shuttle mission are to deliver and install a pressurized module loaded with supplies and equipment, including an experimental robot known as Robonaut 2, and to attach a spare parts pallet to the space station's power truss. The permanent multi-purpose logistics module, or PMM, eventually will serve as a much-needed storeroom, giving station crews a place to house equipment, trash and other gear after the shuttle fleet is retired.

Assuming an on-time launch, Discovery will dock with the International Space Station around 1:30 p.m. Nov. 3. Two midday spacewalks are planned, one on Nov. 5 and the other on Nov. 7. Undocking is planned for Nov. 10 with landing back at the Kennedy Space Center around 10:40 a.m. on Nov. 12.

Discovery's launch campaign comes amid massive layoffs by shuttle prime contractor United Space Alliance as NASA moves into the program's final three missions. But Stott, who began her NASA career as a shuttle engineer at Kennedy, said morale remains positive and the crew has no increased concerns for safety.

"It's certainly going to be a sad time," she said. "We've already seen quite a few people walk out the door. We've had the chance to come down here and visit several times throughout our training flow and I think what impresses me the most is the spirit that is here with these people. And it's been here forever. This is definitely one of those places where people come to work because it's a heart-and-soul thing, it's not just a job for them.

"And you see that in every aspect of the work that goes on here," she said. "We are truly thankful for that. It gives us confidence in the vehicle and the workforce and the mission that we're going to fly, we know that we'll have success because of them."

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CBS NEWS Coverage of Breaking Space News

By William HARWOOD
CBS News Space Consultant

The shuttle Discovery, mounted atop a mobile launch platform carried by an Apollo-era crawler transporter, was hauled to the launch pad overnight Monday for work to ready the ship for blastoff Nov. 1 on its 39th and final flight.

The 3.2-mile trip from the Vehicle Assembly Building to launch complex 39A began at 7:23 p.m. EDT and was completed at 1:49 a.m. Tuesday when the mobile launch platform was reported "hard down" on its support pedestals at the oceanside pad. With good weather expected, a protective gantry will be left parked away from the vehicle to give Kennedy Space Center workers a chance to visit the pad and enjoy an unobstructed view of NASA's most experienced orbiter.

On Saturday, the Rotating Service Structure, or RSS, will be retracted again for "family day" at the Florida spaceport, when workers will be allowed to bring their families out for a launch pad drive-by and tours of other shuttle facilities.

"The first thing we're going to do is get all the systems connected up so we can start validating the systems, the boosters, the tank and the orbiter, make sure we have communications back to the firing room and so forth," said Stephanie Stilson, the engineer in charge of Discovery's ground processing.

"A little bit different for us is we're going to leave the RSS retracted all day (Tuesday) and let employees come out and take pictures, which is something new we have not done before. So that's a great opportunity for the workforce. After we do our picture taking, we'll roll the RSS back to the mate position and get busy doing all the systems checkout and testing. Family day, Saturday, we're going to retract it back. The next big event is the payload coming out on the seventh (of October)."

Discovery's crew -- commander Steven Lindsey, pilot Eric Boe, Michael Barratt, Nicole Stott and spacewalkers Timothy Kopra and Al Drew -- plans to strap in for a dress-rehearsal countdown Oct. 15. An executive-level flight readiness review to assess the shuttle's processing and to set an official launch date is scheduled to begin Oct. 19.

As of this writing, launch is targeted for 4:40 p.m. on Nov. 1. Docking with the International Space Station is expected Nov. 3 with spacewalks on tap Nov. 5 and 7. Undocking is expected around 5:40 a.m. EST on Nov. 10, with landing back at the Kennedy Space Center around 10:39 a.m. on Nov. 12.

NASA plans to follow Discovery's mission with launch of shuttle Endeavour Feb. 26 on a mission to deliver a $2 billion particle physics experiment to the space station, along with additional supplies and equipment. Program managers are hoping NASA's 2011 budget will include funding for a final flight by the shuttle Atlantis next June. The Senate version of the budget includes funding for the mission but the House version would require NASA to pay for it.

Either way, shuttle mission STS-133 will be the final flight for Discovery, NASA's third shuttle, which first took off in August 1984.

"I try not to think about it being the end for Discovery, but I do feel a bit sad, mainly because of the friends I've made on the team and the fact that in the future a lot of those friends won't still be working with me directly," Stilson told reporters late Monday. "That's the biggest part, is thinking, OK, gosh, we're not going to walk in every day and see each other and go and see Discovery and check on the vehicle and have that commonality anymore. We always will from a history perspective, but not in a day-to-day perspective. So it is a little bit heart wrenching when I think about it."

Despite the prospect of looming layoffs at the Florida spaceport, Stilson said she has no concerns about the quality of the processing team's work.

"I was concerned about that with October (layoffs) coming up and with the way things are with the workforce," she said. "But I've really just seen people stay very focused and very upbeat. Everybody handles it differently, so you see different personalities in different ways. But for the most part when I talk to folks and say, you know, what are your plans for the future, what are you doing now, how are things going, a lot of them are saying 'I'm going to stay as long as you'll let me stay here.'

"Some folks have left, they've taken other opportunities, folks I wish could have stayed. ... So we've lost some good folks, but the folks behind them are stepping up and filling in the gaps and working well together. I've been very impressed by the contractor workforce as to the way they've handled it."

She said shuttle program managers are "keeping a very close eye" on flight safety, telling the team "that if at any point in time anybody feels that we're not in a good place, we will stop and redirect and start over if we need to."

"But right now I have no fears of what we've done so far with the team we have now and I have no concerns about what we'll do in the future," she said. "If we get to a point where something is not going the way it should, we know to stop and take care of it."

Rollout pictures are posted on the Space/10 Updates page.

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CBS NEWS Coverage of Breaking Space News

12:40 PM, 09/11/10 Update: Shuttle Discovery bolted to external tank

By William HARWOOD
CBS News Space Consultant

Engineers successfully re-positioned a wayward nut in the shuttle Discovery's aft engine compartment and finished bolting the orbiter to its external fuel tank early Saturday, keeping the ship on track for roll out to pad 39A Sept. 20 and launch on the ship's 39th and final mission Nov. 1.

Discovery was hauled from its processing hangar to the Vehicle Assembly Building Thursday. A large sling was attached to the orbiter late in the day and the shuttle was rotated vertical and lifted into the high bay where its external tank and boosters were waiting.

Engineers successfully attached a large separation system bolt on the lower right side of the shuttle's belly, but an internal nut on the left side near a 17-inch liquid hydrogen feed line slipped out of position and fell away inside the aft compartment. The explosive bolts are part of a system that ensures the tank separates from the shuttle after the ship reaches orbit.

Troubleshooters initially worried Discovery would have to be removed from the tank and placed back in a horizontal orientation to make repairs. But they later concluded they could safely open the aft compartment, set up access platforms and reposition the nut with Discovery in a vertical and partially mated configuration.

That work was completed early Saturday and the ship was "hard mated" to the tank at 9:27 a.m. EDT.

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CBS NEWS Coverage of Breaking Space News

1:00 PM, 09/10/10 Update: Engineers troubleshoot shuttle/external tank attachment problem

By William HARWOOD
CBS News Space Consultant

Engineers attaching the shuttle Discovery to its external fuel tank ran into problems Friday when an internal nut used to attach a separation bolt to the belly of the orbiter slipped out of position. Re-positioning the mis-aligned nut will require access to the shuttle's aft engine compartment, sources said, but it was not immediately clear what might be required to provide that access with Discovery not yet firmly attached to its external tank.

Discovery was moved from its processing hangar to the Vehicle Assembly Building Thursday. A large sling was attached to the orbiter and the shuttle was rotated vertical and lifted into the high bay where its external tank and boosters were waiting. Roll out to launch pad 39A is scheduled for the evening of Sept. 20. Launch is targeted for Nov. 1.

A NASA spokesman said the problem occurred as engineers were attaching the left-side main separation bolt, part of the system used to ensure the shuttle separates from its external tank after reaching orbit.

"The nut on the shuttle side of things basically fell out of reach and they're not able to physically get at this nut at the moment," the spokesman said. "We already had a soft mate. We're at the point where hard mate is on hold temporarily while the engineers meet about this."

It is not yet clear whether engineers can gain access to the aft compartment to reposition the nut with the shuttle in its current vertical orientation, not yet fully attached to the external tank. Sources said engineers may have to move the shuttle back to a horizontal orientation, on its transporter, to gain access to the aft.

Discovery is scheduled to blast off Nov. 1 on its 39th and final mission, a flight to deliver supplies and a cargo storage module to the International Space Station. Before a water main break that delayed Discovery's roll over to the VAB by one day, engineers had 13 days of contingency time built into the processing schedule.

If Discovery is not off the ground by Nov. 5, the flight could face a lengthy delay because of conflicts with upcoming spacewalks, Russian and European launches and so-called "beta angle cutouts," periods when the angle between the sun and the plane of the space station's orbit results in extreme temperatures.

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CBS NEWS Coverage of Breaking Space News

1:15 PM, 09/09/2010/10 Update: Shuttle Discovery moved to VAB for attachment to external tank and boosters

By William HARWOOD
CBS News Space Consultant

Running a day late because of a ruptured water main, the shuttle Discovery was hauled from its processing hangar to the Vehicle Assembly Building Thursday for attachment to an external tank and twin solid-fuel boosters. If all goes well, the orbiter will be moved to launch pad 39A Sept. 21, setting the stage for launch Nov. 1 on a space station resupply mission.

It will be the shuttle program's 133rd flight and the 39th and final voyage of Discovery before NASA's oldest shuttle is retired and put on public display, most likely at the Smithsonian Institution's National Air and Space Museum in Washington.

During the short "rollover" from Orbiter Processing Facility No. 3 to the cavernous VAB, the transporter carrying Discovery was parked in the open for two-and-a-half hours to give Kennedy Space Center workers a chance to pose for pictures with the orbiter as it took the first step toward its final fligiht.

Shuttle program managers plan to hold a two-day flight readiness review starting Oct. 6. Discovery's crew -- commander Steven Lindsey, pilot Eric Boe, Michael Barratt, Nicole Stott and spacewalkers Timothy Kopra and Al Drew -- plans to fly to the Kennedy Space Center Oct. 12 to review launch site emergency procedures and to participate in a dress-rehearsal countdown Oct. 15.

Senior NASA managers plan to hold an executive-level flight readiness review Oct. 19 to assess Discovery's processing and to set an official launch date.

If all goes well, Lindsey and his crewmates will fly back to Florida Oct. 28 for the start of the shuttle's countdown the next day. As of this writing, launch is targeted for 4:40:13 p.m. EDT on Nov. 1, roughly the moment Earth's rotation carries launch complex 39 into the plane of the International Space Station's orbit.

Assuming an on-time launch, Lindsey will guide Discovery to a docking at the space station's forward port around 1 p.m. on Nov. 3. The first of two spacewalks by Kopra and Drew is scheduled to begin around 10:35 a.m. on Nov. 5 to install an electrical cable, stow a failed ammonia pump module and to carry out other maintenance tasks.

The next day, Nov. 6, the astronauts plan to attach a pressurized cargo module to the central Unity module's Earth-facing port before enjoying a bit of off-duty time and gearing up for the second spacewalk.

A few hours after the switch from daylight savings time to standard time in the U.S. early Nov. 7, Kopra and Drew will begin their second spacewalk around 8:35 a.m. EST to carry out a variety of unrelated maintenance tasks.

If all goes well, Discovery will undock from the space station around 5:48 a.m. Nov. 10 and land back at the Kennedy Space Center around 10:43 a.m. on Nov. 12.

The shuttle Endeavour is scheduled for launch on the final currently planned shuttle mission Feb. 26, 2011. NASA is lobbying for a third and final flight by the shuttle Atlantis next June, but it is not yet clear whether funding can be arranged in time.

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CBS NEWS Coverage of Breaking Space News

01:00 PM, 09/03/10 Update: Follow-on spacewalk tasks deferred to November shuttle flight

By William HARWOOD
CBS News Space Consultant

In the wake of a three-spacewalk coolant pump replacement, space station managers decided this week to defer additional maintenance work until the next shuttle crew arrives in November.

The unexpected failure of an ammonia pump module July 31 forced station astronauts Douglas Wheelock and Tracy Caldwell Dyson to forego installation of an electrical cable that is needed before a storage module can be attached to the station during the November shuttle visit.

Instead, they installed a replacement pump over the course of three EVAs and left the faulty unit mounted on an attachment fixture at the base of the station's robot arm transporter. The old pump needs to be moved to an external storage platform.

Caldwell Dyson, Mikhail Kornienko and Expedition 24 commander Alexander Skvortsov are scheduled to return to Earth Sept. 24. Three fresh crew members - Scott Kelly, Alexander Kaleri and Oleg Skripochka - are scheduled for launch Oct. 7 U.S. time, three weeks before the Nov. 1 launch of the shuttle Discovery, to join Wheelock, Shannon Walker and Fyodor Yurchikhin as part of the Expedition 25 crew.

Flight planners debated having Kelly and Wheelock carry out a spacewalk before the shuttle's arrival to move the old pump and install the extension cable. But senior managers decided this week to move those tasks to the Discovery crew's timeline.

Two spacewalks by shuttle flight engineer Timothy Kopra and Al Drew already were planned for Discovery's mission to complete a variety of maintenance tasks that had been deferred from earlier missions and station expeditions.

As it now stands, Kopra and Drew will install the electrical cable and move the old pump to external storage platform No. 2 during their first spacewalk two days after docking. The cargo module will be installed the day after that using the station's robot arm.

The second spacewalk the following day will include a variety of already planned maintenance tasks. Fight planners are considering whether to add another EVA to the crew's timeline to complete additional maintenance work.

In the near term, Russian engineers are gearing up to launch an unmanned Progress supply ship Sept. 8, at 7:11 a.m. EDT, from the Baikonur Cosmodrome in Kazakhstan. If all goes well, the robotic craft will dock at the Zvezda command module's aft port around 8:40 a.m. on Sept. 10.

The Progress 39 vehicle is loaded with 1,918 pounds of propellant, 2,645 pounds of spare parts, experiment hardware, food and other supplies, 110 pounds of oxygen and 375 pounds of water.

Two weeks later, Skvortsov, Kornienko and Caldwell Dyson are scheduled to undock from the station around 11:02 p.m. Sept. 23 and to land in Kazakhstan around 2:22 a.m. on Sept. 24.

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CBS NEWS STS-133 STATUS REPORT: 04 Posted: 2:55 PM, 7/6/10

By William HARWOOD
CBS News Space Analyst

Changes and additions:

2:55 PM, 7/6/10,/10 Update: United Space Alliance announces shuttle layoffs

With only two shuttle flights remaining on NASA's manifest, prime contractor United Space Alliance plans to lay off about 15 percent of its 8,100-strong space shuttle workforce Oct. 1, company officials announced Tuesday.

Eight hundred to 1,000 jobs will be lost at the Kennedy Space Center in Florida, with another 300 to 400 in Texas and 10 in Alabama. Another 743 USA jobs were lost in two earlier rounds of layoffs.

"Our workforce has known for several years that the space shuttle program has been scheduled to end, but layoffs are always difficult for everyone involved," Virginia Barnes, USA President and chief executive officer, said in a statement. "The accomplishments of this team are unmatched in human spaceflight. We acknowledge the tremendous talent and commitment of our teammates and congratulate them on their achievements."

NASA plans to launch the shuttle Discovery Nov. 1 on a mission to deliver critical supplies and equipment to the International Space Station. The final currently planned flight, using the shuttle Endeavour, is scheduled for launch Feb. 26.

Both of those flights are covered by the shuttle program's current budget and a congressional pledge for an additional $600 million that originally was intended to cover program costs through the end of the calendar year. Shuttle managers now say they can stretch current funding to cover Endeavour's flight in February.

NASA managers are lobbying for a third and final space station resupply mission with the shuttle Atlantis in the June 2011 timeframe. Atlantis is being processed for stand-by duty as an emergency rescue vehicle for Endeavour's crew, but if a rescue flight is not needed, NASA would like to launch Atlantis on a final resupply mission.

By launching Atlantis with a crew of four, NASA would not need a second shuttle for stand-by duty. Instead, a four-person crew could seek safe haven aboard the space station, if necessary, and get back to Earth aboard Russian Soyuz spacecraft.

Shuttle program managers are studying cost projections and potential savings to see how far they can stretch current funding. The shuttle program normally costs about $200 million a month to operate and even with projected savings, sources say additional money almost certainly will be required to cover a final mission with Atlantis.

NASA managers are expected to make a decision in August. A USA spokeswoman said the Atlantis mission, whether it is added or not, will not affect the current round of projected layoffs.

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CBS NEWS STS-133 STATUS REPORT: 03 Posted: 12:25 PM, 7/1/10

By William HARWOOD
CBS News Space Analyst

Changes and additions:

12:25 PM, 7/1/10,/10 Update: Shuttle target dates reset for Nov. 1 and Feb. 26

After assessing payload processing issues and projected traffic to and from the International Space Station, NASA managers Thursday formally retargeted the program's final two missions for launches Nov. 1 and Feb. 26.

The shuttle Discovery, which had been scheduled for launch Sept. 16 on mission STS-133, is now targeted for liftoff at 4:33 p.m. EDT on Nov. 1. The primary goals of the two-spacewalk mission are to deliver spare parts and supplies, along with a modified cargo transfer module that will be permanently attached to the station to provide additional storage space.

The shuttle Endeavour, which had been targeted for launch around Nov. 26, was reset for takeoff at 4:19 p.m. EST on Feb. 26, 2011. The goal of that mission is to deliver the $1.5 billion Alpha Magnetic Spectrometer to the station, along with a pallet of critical spare parts that will be mounted on the lab's power truss.

NASA managers asked engineers to reassess the launch dates with an official "change request" that went out June 22. At that time, the proposed target dates were Oct. 29 for STS-133 and Feb. 28 for STS-134.

The STS-133 slip was required to complete preparations of critical spares that will be launched in the Permanent Multi-Purpose Module, or PMM, including a pump package, a robotic test article known as "Robonaut" and a heat exchanger. Other hardware required for the Alpha Magnetic Spectrometer and spares for the station's life support system also were on tight schedules.

Two Russian launches planned for October forced NASA to consider the Oct. 29 target. Then, during the review process, planners realized the target date was in conflict with an already scheduled air show and maintenance planned at the Air Force Range that provides tracking and telemetry support for all rockets launched from Florida. As a result, agency managers settled on Nov. 1.

Assuming the schedule holds up, commander Steven Lindsey pilot Eric Boe, station veterans Nicole Stott and Michael Barratt and spacewalkers Alvin Drew and Timothy Kopra, another station veteran, will blast off from pad 39A at 4:33 p.m. on Nov. 1. Docking with the International Space Station would be expected around 12:52 p.m. on Nov. 3.

The PMM would be installed on Nov. 4, followed by spacewalks with Kopra and Drew on Nov. 5 and 7. Undocking would be targeted for 7:13 a.m. on Nov. 10 with landing back at the Kennedy Space Center on tap around 12 p.m. Friday, Nov. 12.

Endeavour's launching on mission STS-134 originally was scheduled for July, but the flight was delayed to late November after a decision to replace the magnet at the heart of the Alpha Magnetic Spectrometer. The AMS payload will not be delivered to the Florida space center until late August and three months of on-site processing are required before launch.

A late-November/early December launch was ruled out because of conflicts with other planned station launches. Temperature constraints related to the station's orbit prevented a launch in January and range conflicts with other unmanned missions pushed the approved launch date to Feb. 26.

Endeavour will be commanded by veteran Mark Kelly. His crewmates are pilot Gregory Johnson, Hubble veteran Andrew Feustel, European Space Agency astronaut Roberto Vittori and station veterans Gregory Chamitoff and Mike Fincke.

NASA originally planned to end shuttle operations by the end of fiscal 2010, launching Endeavour in July followed by Discovery in mid September. But Congress already had promised an additional $600 million to cover shuttle costs through the end of the calendar year to avoid the sort of schedule pressure blamed in part for the Challenger and Columbia mishaps.

NASA managers then came up with additional savings, permitting operations through February or March without additional appropriations.

The shuttle Atlantis is being processed to serve as an emergency rescue vehicle for Endeavour's crew. But if a rescue flight is not needed, NASA managers believe the standby shuttle could be launched with a crew of four, relying on Russian Soyuz capsules to ferry the crew members home if a major problem blocked a safe re-entry.

Concerned about the near-term lack of a large rocket to deliver heavy payloads after the shuttle fleet is retired, NASA managers want to take advantage of the boosters and external tank being prepared for Atlantis' rescue mission that otherwise would go to waste.

But additional funding would be required and it's not yet clear whether NASA has the necessary political support. A decision is expected in August.

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CBS NEWS STS-133 STATUS REPORT: 02 Posted: 5:55 PM, 6/22/10

By William HARWOOD
CBS News Space Analyst

Changes and additions:

5:55 PM, 6/22/10,/10 Update: NASA begins two-week review of proposed shuttle launch date changes

NASA managers Tuesday asked shuttle engineers to assess retargeting the final two space shuttle missions, moving launch of a mid-September flight with Discovery to Oct. 29 and a late November flight by Endeavour to Feb. 28. The changes would give engineers more time to optimize payloads bound for the International Space Station and avoid launch conflicts with other flights to the lab complex.

The status of a proposed final fight of the shuttle Atlantis next June to deliver a final load of supplies and equipment remains unresolved. Bill Gerstenmaier, director of space operations at NASA headquarters, said earlier this year he hoped to have a decision by the end of this month, but officials said Tuesday the discussion had been deferred to the August timeframe.

A decision on delaying the next two missions, however, is expected July 1, after a two-week review.

Assuming an Oct. 29 target date, Discovery would blast off at 5:44 p.m. and dock with the station the afternoon of Oct. 31. Two spacewalks would be carried out Nov. 2 and 4. Discovery would undock the morning of Nov. 7 and land back at the Kennedy Space Center the afternoon of Nov. 9.

Shuttle mission STS-133 will be commanded by former chief astronaut Steven Lindsey. His crewmates are pilot Eric Boe, station veterans Nicole Stott and Michael Barratt and spacewalkers Alvin Drew and Timothy Kopra, another station veteran.

Endeavour, commanded by Mark Kelly, would blast off around 5:31 p.m. on Feb. 28 to deliver critical supplies and a $1.5 billion physics experiment to the space station. Joining Kelly for mission STS-134 will be pilot Gregory Johnson, Hubble veteran Andrew Feustel, European Space Agency astronaut Roberto Vittori and station veterans Gregory Chamitoff and Mike Fincke.

NASA originally planned to end shuttle operations by the end of fiscal 2010, launching Endeavour in July and Discovery in mid September. But problems with the Alpha Magnetic Spectrometer scheduled for launch aboard Endeavour forced program managers to delay the July flight to the end of November.

Congress earlier promised an additional $600 million to cover shuttle costs through the end of the calendar year to avoid the sort of schedule pressure blamed in part for the Challenger and Columbia mishaps.

NASA managers then came up with additional savings, permitting operations through February or March without additional appropriations. Delaying Discovery to late October and Endeavour to late February will give engineers more time to optimize the equipment and spare parts being launched to the station.

Atlantis is being processed to serve as an emergency rescue vehicle for Endeavour's crew. But if a rescue flight is not needed, NASA managers believe the standby shuttle could be launched with a crew of four, relying on Russian Soyuz capsules to ferry the crew members home if a major problem blocked a safe re-entry.

Concerned about the near-term lack of a large rocket to deliver heavy payloads after the shuttle fleet is retired, NASA managers want to take advantage of the boosters and external tank being prepared for Atlantis' rescue mission that otherwise would go to waste.

But additional funding would be required and it's not yet clear whether NASA has the necessary political support.