Realtime coverage of STS-135 launch countdown
By WILLIAM HARWOOD
CBS News
05:00 a.m. EDT Update: Astronauts head to launch pad
KENNEDY SPACE CENTER, FL--
NASA managers evaluating threatening weather have decided to press ahead with an attempt to launch the shuttle Atlantis today on the program's 135th and final mission. Liftoff is targeted for 11:26:46 a.m. EDT.
Because of expected large crowds and heavy traffic, NASA Launch Director Mike Leinbach had held open the option of calling off today's attempt at the launch-minus-four-hour mark, depending on the forecast, to make sure the team could get home and make it back in time for a second attempt Saturday.
While the forecast remains 70 percent "no go," NASA's mission management team opted to press ahead for an attempt today in hopes of catching a break in the cloud cover. If the flight is scrubbed late in the countdown, NASA likely will be forced to delay another attempt to Sunday, at 10:38:31 a.m.
Weather aside, there are no technical problems of any significance at pad 39A and the countdown is proceeding smoothly toward the opening of the launch window.
05:00 a.m. EDT Update: Shuttle fueling complete
KENNEDY SPACE CENTER, FL--Despite a dismal forecast, NASA managers early Friday cleared engineers to load the shuttle Atlantis with more than a half-million gallons of rocket fuel and to press ahead for an attempt to launch the orbiter on the program's 135th and final mission. Liftoff is targeted for 11:26:46 a.m. EDT (GMT-4).
But with a 70 percent chance of stormy weather, mission managers held open the option of standing down later this morning depending on actual conditions.
"Mike Moses, the mission management team chair, said some people might call it silly to try and play in the rain this morning, but he said we're going to absolutely try for tanking," said countdown commentator Allard Beutel. "The shuttle launch director, Mike Leinbach, was in 100 percent agreement with him, that trying for tanking was the right option to do.
"But throughout the overnight and closer to the dawn early morning hours, between six and seven o'clock, they'll keep their eyes on the forecast, of course, all night long, but around that time, they'll start getting a very focused look on the weather and see whether it's the right thing to proceed towards launch or whether the forecast really is getting worse. We'll look at perhaps standing down at that point. But at least at the moment, tanking operations are set to begin momentarily."
Hoping for the best, engineers began pumping supercold liquid oxygen and liquid hydrogen through transfer lines to pad 39A at 2:01 a.m. EDT (GMT-4). Routed through Atlantis' main engine plumbing to condition the hardware to cryogenic temperatures, the propellants then flowed into oxygen and hydrogen reservoirs in the shuttle's huge external tank. Three hours later, at 4:58 a.m., the tank was full and engineers transitioned to "stable replenish" mode.
There are no technical problems of any significance at the launch pad. A hydrogen valve installed on main engine No. 3 after a leak was detected during a fueling test last month is operating normally, as are the shuttle's external tank and other major components.
Commander Christopher Ferguson, pilot Douglas Hurley, Sandra Magnus and flight engineer Rex Walheim plan to begin strapping in at 8:06 a.m. to await launch.
The updated forecast improves to 60 percent "go" Saturday with a 50 percent chance of acceptable weather Sunday. Going into the final launch campaign, NASA managers said Atlantis had to be off the ground by Sunday to avoid a conflict with the launch next week of an Air Force navigation satellite.
But agency officials said Thursday it might be possible to extend the shuttle launch window through Monday if the Air Force agreed to delay the satellite launch by one day. But no final decisions have been made.
Here is a list of major remaining countdown events (in EDT):
CBS News
05:00 a.m. EDT Update: Astronauts head to launch pad
 |
| The Atlantis astronauts head for the launch pad to await liftoff on NASA's final shuttle mission. Left to right: Sandra Magnus, Rex Walheim, pilot Douglas Hurley and commander Christopher Ferguson. (Credit: NASA TV) |
NASA managers evaluating threatening weather have decided to press ahead with an attempt to launch the shuttle Atlantis today on the program's 135th and final mission. Liftoff is targeted for 11:26:46 a.m. EDT.
Because of expected large crowds and heavy traffic, NASA Launch Director Mike Leinbach had held open the option of calling off today's attempt at the launch-minus-four-hour mark, depending on the forecast, to make sure the team could get home and make it back in time for a second attempt Saturday.
While the forecast remains 70 percent "no go," NASA's mission management team opted to press ahead for an attempt today in hopes of catching a break in the cloud cover. If the flight is scrubbed late in the countdown, NASA likely will be forced to delay another attempt to Sunday, at 10:38:31 a.m.
Weather aside, there are no technical problems of any significance at pad 39A and the countdown is proceeding smoothly toward the opening of the launch window.
05:00 a.m. EDT Update: Shuttle fueling complete
KENNEDY SPACE CENTER, FL--Despite a dismal forecast, NASA managers early Friday cleared engineers to load the shuttle Atlantis with more than a half-million gallons of rocket fuel and to press ahead for an attempt to launch the orbiter on the program's 135th and final mission. Liftoff is targeted for 11:26:46 a.m. EDT (GMT-4).
But with a 70 percent chance of stormy weather, mission managers held open the option of standing down later this morning depending on actual conditions.
 |
| Hoping for a break in the weather, engineers were cleared to fuel the shuttle Atlantis early Friday, setting the stage for launch on NASA's final shuttle mission. (Credit: NASA TV) |
 |
| (Credit: NASA TV) |
Hoping for the best, engineers began pumping supercold liquid oxygen and liquid hydrogen through transfer lines to pad 39A at 2:01 a.m. EDT (GMT-4). Routed through Atlantis' main engine plumbing to condition the hardware to cryogenic temperatures, the propellants then flowed into oxygen and hydrogen reservoirs in the shuttle's huge external tank. Three hours later, at 4:58 a.m., the tank was full and engineers transitioned to "stable replenish" mode.
There are no technical problems of any significance at the launch pad. A hydrogen valve installed on main engine No. 3 after a leak was detected during a fueling test last month is operating normally, as are the shuttle's external tank and other major components.
Commander Christopher Ferguson, pilot Douglas Hurley, Sandra Magnus and flight engineer Rex Walheim plan to begin strapping in at 8:06 a.m. to await launch.
The updated forecast improves to 60 percent "go" Saturday with a 50 percent chance of acceptable weather Sunday. Going into the final launch campaign, NASA managers said Atlantis had to be off the ground by Sunday to avoid a conflict with the launch next week of an Air Force navigation satellite.
But agency officials said Thursday it might be possible to extend the shuttle launch window through Monday if the Air Force agreed to delay the satellite launch by one day. But no final decisions have been made.
Here is a list of major remaining countdown events (in EDT):
HH...MM...SS...EDT...........EVENT
06...20...00...05:01 AM......Begin 2-hour 30-minute built-in hold (T-minus 3 hours)
06...20...00...05:01 AM......Closeout crew to white room
06...20...00...05:01 AM......External tank in stable replenish mode
06...17...00...05:04 AM......Ascent flight control team on console
06...05...00...05:16 AM......Astronaut support personnel comm checks
05...35...00...05:46 AM......Pre-ingress switch reconfig
04...51...00...06:30 AM......NASA TV launch coverage begins
04...25...00...06:56 AM......Final crew weather briefing
04...15...00...07:06 AM......Crew suit up begins
03...50...00...07:31 AM......Resume countdown (T-minus 3 hours)
03...45...00...07:36 AM......Crew departs O&C building
03...15...00...08:06 AM......Crew ingress
02...25...00...08:56 AM......Astronaut comm checks
02...00...00...09:21 AM......Hatch closure
01...30...00...09:51 AM......White room closeout
01...10...00...10:11 AM......Begin 10-minute built-in hold (T-minus 20m)
01...00...00...10:21 AM......NASA test director countdown briefing
01...00...00...10:21 AM......Resume countdown (T-minus 20m)
00...59...00...10:22 AM......Backup flight computer loads OPS 1 software
00...55...00...10:26 AM......KSC area clear to launch
00...49...00...10:32 AM......Begin final built-in hold (T-minus 9m)
00...24...00...10:57 AM......NTD launch status verification
00...09...00...11:17:46 AM...Resume countdown (T-minus 9m)
00...07...30...11:19:16 AM...Orbiter access arm retraction
00...05...00...11:21:46 AM...Launch window opens
00...05...00...11:21:46 AM...Hydraulic power system (APU) start
00...04...55...11:21:51 AM...Terminate LO2 replenish
00...04...00...11:22:46 AM...Purge sequence 4 hydraulic system test
00...04...00...11:22:46 AM...Inertial measurement units to inertial
00...03...55...11:22:51 AM...Aerosurface movement checks
00...03...30...11:23:16 AM...Main engine steering test
00...02...55...11:23:51 AM...LO2 tank pressurization
00...02...35...11:24:11 AM...Fuel cells to internal reactants
00...02...30...11:24:16 AM...Clear caution-and-warning memory
00...02...00...11:24:46 AM...Crew closes visors
00...01...57...11:24:49 AM...LH2 tank pressurization
00...00...50...11:25:56 AM...SRB joint heater deactivation
00...00...31...11:26:15 AM...Shuttle computers take control of countdown
00...00...21...11:26:25 AM...SRB steering test
00...00...07...11:26:39 AM...Main engine start (T-6.6 seconds)
00...00...00...11:26:46 AM...SRB ignition (LAUNCH)