Weathering storms, Endeavour fueled for launch
Editor's note...
KENNEDY SPACE CENTER, FL--The shuttle Endeavour's external tank has been loaded with a half-million gallons of liquid oxygen and hydrogen rocket fuel and forecasters are hopeful low clouds will break up as a front moves through, clearing the way for launch on NASA's next-to-last shuttle mission.
Endeavour's fueling began at 6:22 a.m. and the tank went into "stable replenish" mode three hours later, at 9:24 a.m.. There were no problems with a 7-inch gaseous hydrogen vent line attached to the side of the tank that delayed the previous shuttle launching.
The only technical problem under discussion early today was a slight pressure differential between the propellant tanks in the shuttle's right-side orbital maneuvering system rocket pod. After troubleshooting, engineers decided to open a crossfeed valve to equalize pressures between the left and right rocket pods.
Forecasters monitoring fast-moving storm cells south of the Kennedy Space Center during the later stages of fueling said it appeared the bad weather would stay away from the launch pad, although low clouds and blustery winds at the shuttle's emergency runway could cause problems later.
But for now, the forecast remains 70 percent "go" for a launching at 3:47:55 p.m. EDT (GMT-4).
NASA originally hoped to launch Endeavour April 19, but the flight was delayed to make way for the launch and docking of a Russian Progress supply ship that blasted off from the Baikonur Cosmodrome in Kazakhstan on Wednesday. The unmanned supply ship glided to a smooth linkup with the space station at 9:28 a.m. Friday.
Endeavour's crew -- commander Mark Kelly, pilot Gregory H. Johnson, Michael Fincke, Gregory Chamitoff, Andrew Feustel and European Space Agency astronaut Roberto Vittori -- got up at 6 a.m. After breakfast and final medical checks, Kelly and Johnson will get a weather update before donning their bright orange pressure suits and heading to launch pad 39A around noon to begin strapping in for launch.
Kelly's twin brother Scott, who just got back from a long-duration stay aboard the International Space Station, joked Thursday night in a Twitter feed that he was "ready if replacement is required." Kelly's wife, Arizona Rep. Gabrielle Giffords, flew to Florida Wednesday, her first major trip since an assassination attempt in January. President Barack Obama and his family are scheduled to fly in later today, landing at the nearby Cape Canaveral Air Force Station.
Thunderstorms pounded Florida's Space Coast late Thursday, delaying work to roll a protective gantry away from the shuttle to clear the way for fueling. But the storms dissipated enough before midnight to permit the rotating service structure to be pulled away about five hours behind schedule. Engineers worked through the early morning hours to make up lost time and fueling began on schedule at 6:22 a.m.
"Launch teams are not working any issues right now that would prevent us from launching on time at 3:47 p.m. Eastern today," NASA spokesman Allard Beutel said just before fueling began. "Currently, forecasters are calling for a 70 percent of good weather for this afternoon's launch."
The three-hour fueling procedure began when ultra-cold liquid hydrogen and oxygen began flowing through transfer lines to inlets on either side of the shuttle's aft engine compartment. Before entering the tank, the propellants circulate through the ship's three main engines to acclimate the propulsion system plumbing to cyrogenic temperatures.
Here is a timeilne for the remainder of today's countdown (in EDT):
- Posted at 06:50 AM EDT, 04/29/11: Weathering storms, Endeavour fueled for launch
- Updated at 09:45 AM EDT, 04/29/11: Fueling complete; hydrogen vent line working normally
- Updated at 10:30 AM EDT, 04/29/11: Progress supply ship docks with space station
- By WILLIAM HARWOOD
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| The shuttle Endeavour atop pad 39A during fueling early Friday. (Credit: NASA TV) |
Endeavour's fueling began at 6:22 a.m. and the tank went into "stable replenish" mode three hours later, at 9:24 a.m.. There were no problems with a 7-inch gaseous hydrogen vent line attached to the side of the tank that delayed the previous shuttle launching.
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| A gaseous hydrogen vent line attached to Endeavour's external tank is performing normally. A leak in the line delayed a shuttle launch earlier this year. (Credit: NASA TV) |
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| Lightning illuminates launch pad 39A late Thursday as storms pounded the Kennedy Space Center. (Credit: NASA) |
But for now, the forecast remains 70 percent "go" for a launching at 3:47:55 p.m. EDT (GMT-4).
NASA originally hoped to launch Endeavour April 19, but the flight was delayed to make way for the launch and docking of a Russian Progress supply ship that blasted off from the Baikonur Cosmodrome in Kazakhstan on Wednesday. The unmanned supply ship glided to a smooth linkup with the space station at 9:28 a.m. Friday.
Endeavour's crew -- commander Mark Kelly, pilot Gregory H. Johnson, Michael Fincke, Gregory Chamitoff, Andrew Feustel and European Space Agency astronaut Roberto Vittori -- got up at 6 a.m. After breakfast and final medical checks, Kelly and Johnson will get a weather update before donning their bright orange pressure suits and heading to launch pad 39A around noon to begin strapping in for launch.
Kelly's twin brother Scott, who just got back from a long-duration stay aboard the International Space Station, joked Thursday night in a Twitter feed that he was "ready if replacement is required." Kelly's wife, Arizona Rep. Gabrielle Giffords, flew to Florida Wednesday, her first major trip since an assassination attempt in January. President Barack Obama and his family are scheduled to fly in later today, landing at the nearby Cape Canaveral Air Force Station.
Thunderstorms pounded Florida's Space Coast late Thursday, delaying work to roll a protective gantry away from the shuttle to clear the way for fueling. But the storms dissipated enough before midnight to permit the rotating service structure to be pulled away about five hours behind schedule. Engineers worked through the early morning hours to make up lost time and fueling began on schedule at 6:22 a.m.
"Launch teams are not working any issues right now that would prevent us from launching on time at 3:47 p.m. Eastern today," NASA spokesman Allard Beutel said just before fueling began. "Currently, forecasters are calling for a 70 percent of good weather for this afternoon's launch."
The three-hour fueling procedure began when ultra-cold liquid hydrogen and oxygen began flowing through transfer lines to inlets on either side of the shuttle's aft engine compartment. Before entering the tank, the propellants circulate through the ship's three main engines to acclimate the propulsion system plumbing to cyrogenic temperatures.
Here is a timeilne for the remainder of today's countdown (in EDT):
HH...MM...SS...EDT...........EVENT
Fri 04/29/11
06...20...00...09:22 AM......Begin 2-hour 30-minute built-in hold (T-minus 3 hours)
06...20...00...09:22 AM......Closeout crew to white room
06...20...00...09:22 AM......External tank in stable replenish mode
06...17...00...09:25 AM......Ascent flight control team on console
06...05...00...09:37 AM......Astronaut support personnel comm checks
05...35...00...10:07 AM......Pre-ingress switch reconfig
05...12...00...10:30 AM......NASA TV launch coverage begins
04...25...00...11:17 AM......Final crew weather briefing
04...15...00...11:27 AM......Crew suit up begins
03...50...00...11:52 AM......Resume countdown (T-minus 3 hours)
03...45...00...11:57 AM......Crew departs Operations and Checkout building
03...15...00...12:27 PM......Crew ingress
02...25...00...01:17 PM......Astronaut comm checks
02...00...00...01:42 PM......Hatch closure
01...30...00...02:12 PM......White room closeout
01...10...00...02:32 PM......Begin 10-minute built-in hold (T-minus 20m)
01...00...00...02:42 PM......NASA test director countdown briefing
01...00...00...02:42 PM......Resume countdown (T-minus 20m)
00...59...00...02:43 PM......Backup flight computer to OPS 1
00...55...00...02:47 PM......KSC area clear to launch
00...49...00...02:53 PM......Begin final built-in hold (T-minus 9m)
00...24...00...03:18 PM......NTD launch status verification
00...09...00...03:38:55 PM...Resume countdown (T-minus 9m)
00...07...30...03:40:25 PM...Orbiter access arm retraction
00...05...00...03:42:55 PM...Launch window opens
00...05...00...03:42:55 PM...Hydraulic power system (APU) start
00...04...55...03:43:00 PM...Terminate LO2 replenish
00...04...00...03:43:55 PM...Purge sequence 4 hydraulic test
00...04...00...03:43:55 PM...IMUs to inertial
00...03...55...03:44:00 PM...Aerosurface profile
00...03...30...03:44:25 PM...Main engine steering test
00...02...55...03:45:00 PM...LO2 tank pressurization
00...02...35...03:45:20 PM...Fuel cells to internal reactants
00...02...30...03:45:25 PM...Clear caution-and-warning memory
00...02...00...03:45:55 PM...Crew closes visors
00...01...57...03:45:58 PM...LH2 tank pressurization
00...00...50...03:47:05 PM...SRB joint heater deactivation
00...00...31...03:47:24 PM...Shuttle GPCs take control of countdown
00...00...21...03:47:34 PM...SRB steering test
00...00...07...03:47:48 PM...Main engine start (T-6.6 seconds)
00...00...00...03:47:55 PM...SRB ignition (LAUNCH)