NASA sets launch options for Wednesday and Thursday
BY WILLIAM HARWOOD
STORY WRITTEN FOR CBS NEWS "SPACE PLACE" & USED WITH PERMISSION
Posted: July 14, 2009
Engineers replaced rocket nozzle rain covers Tuesday and prepared the shuttle Endeavour for a sixth launch attempt Wednesday, weather permitting, to get a complex space station construction mission underway.
Forecasters are predicting a 60 percent chance of good weather for Endeavour's planned launching at 6:03:10 p.m. EDT. But if the weather or some other problem crops up and launch is delayed a record-tying sixth time, NASA managers Tuesday agreed to make one final launch attempt Thursday before standing down until July 26.
For a launch Wednesday, the Endeavour astronauts will have to revise their flight plan and defer some activities until after the shuttle undocks from the space station. The changes are required to make sure the crew completes the docked phase of the mission and departs on July 28, clearing the way for a Russian Progress supply ship to dock at the lab complex on July 29.
For a launching Thursday, however - the 40th anniversary of the Apollo 11 moon launch - the astronauts would have to eliminate their fifth and lowest priority spacewalk to ensure a July 28 undocking.
The Progress is scheduled for launch July 24 and would normally dock July 27. It can loiter in orbit an additional two days, but it must dock by July 29 at the latest.
NASA managers are hopeful it won't come to that. There are no technical problems of any significance at pad 39A and engineers plan to begin reloading Endeavour's external tank with a half-million gallons of rocket fuel starting at 8:38 a.m. Wednesday.
NASA will provide live television coverage of fueling operations starting at 8:30 a.m., with normal launch coverage starting at 12:30 p.m.
Commander Mark Polansky, pilot Douglas Hurley, Canadian flight engineer Julie Payette, David Wolf, Christopher Cassidy, Thomas Marshburn and space station flight engineer Timothy Kopra plan to begin strapping in around 2:43 p.m. to await launch.
Here are countdown highlights for Wednesday (in EDT; best viewed with fixed-width font):
EDT...........EVENT Wednesday, July 15 08:30 AM......NASA TV fueling coverage begins 08:38 AM......Resume countdown (T-minus 6 hours) 08:38 AM......LO2, LH2 transfer line chilldown 08:48 AM......Main propulsion system chill down 08:48 AM......LH2 slow fill 09:18 AM......LO2 slow fill 09:23 AM......Hydrogen ECO sensors go wet 09:28 AM......LO2 fast fill 09:38 AM......LH2 fast fill 11:38 AM......LH2 replenish 11:38 AM......LO2 replenish 11:38 AM......Begin 2-hour 30-minute built-in hold (T-minus 3 hours) 11:38 AM......Closeout crew to white room 11:38 AM......External tank in stable replenish mode 11:53 AM......Astronaut support personnel comm checks 12:23 PM......Pre-ingress switch reconfig 12:30 PM......NASA TV coverage begins 01:41 PM......Final crew weather briefing 01:51 PM......Crew suit up begins 02:08 PM......Resume countdown (T-minus 3 hours) 02:13 PM......Crew departs O&C building 02:43 PM......Crew ingress 03:33 PM......Astronaut comm checks 03:58 PM......Hatch closure 04:28 PM......White room closeout 04:48 PM......Begin 10-minute built-in hold (T-minus 20m) 04:58 PM......NASA test director countdown briefing 04:58 PM......Resume countdown (T-minus 20m) 04:59 PM......Backup flight computer to OPS 1 05:03 PM......KSC area clear to launch 05:09 PM......Begin final built-in hold (T-minus 9m) 05:39 PM......NTD launch status verification 05:54:10 PM...Resume countdown (T-minus 9m) 05:55:40 PM...Orbiter access arm retraction 05:58:10 PM...Launch window opens 05:58:10 PM...Hydraulic power system (APU) start 05:58:15 PM...Terminate LO2 replenish 05:59:10 PM...Purge sequence 4 hydraulic test 05:59:10 PM...IMUs to inertial 05:59:15 PM...Aerosurface steering profile 05:59:40 PM...Main engine steering test 06:00:15 PM...LO2 tank pressurization 06:00:20 PM...GOX vent arm retraction 06:00:35 PM...Fuel cells to internal reactants 06:00:40 PM...Clear caution-and-warning memory 06:01:10 PM...Crew closes visors 06:01:13 PM...LH2 tank pressurization 06:02:20 PM...Orbiter to internal power 06:02:39 PM...Shuttle computers take control of countdown 06:02:49 PM...SRB steering test 06:03:03 PM...Main engine start (T-6.6 seconds) 06:03:10 PM...SRB ignition (LAUNCH)NASA originally planned to launch Endeavour on June 13, but the flight was scrubbed during fueling when a leak developed where a gaseous hydrogen vent line attaches to the shuttle's external tank. Engineers replaced an internal seal and reset the countdown for a June 17 launch, but the vent line leaked again during fueling and the mission was put on hold.
Engineers eventually traced the problem to a slight misalignment in the vent port housing built into the side of the tank. A more flexible internal seal was installed and modifications were made to the vent line attachment plate to ensure a tight fit. A fueling test July 1 confirmed the vent line was leak free and launch was reset for Saturday, July 11.
But a severe thunderstorm rumbled across the Kennedy Space Center the day before and 11 lightning strikes were recorded at pad 39A. NASA managers decided early July 11 to delay launch one day, to July 12, to give engineers time to make sure Endeavour suffered no lightning-related problems.
With a clean bill of health, NASA pressed ahead for a Sunday launch attempt. But the countdown was called off during a final hold at the T-minus nine-minute mark because of approaching thunderstorms. NASA managers decided to make another attempt Monday, opting not to repair a partially detached rocket nozzle rain cover on a forward thruster.
But again, approaching electrical storms derailed the shuttle's fifth launch attempt. NASA managers then delayed another launch try to Wednesday to give engineers time to replace all the rocket nozzle rain covers protecting the shuttle's forward thrusters.
For the record, two shuttle missions - STS-61C in January 1986 and STS-73 in October 1995 - share the record for launch delays, each suffering through six launch slips before finally taking off on their seventh attempt.