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Countdown ticking for Endeavour's predawn launch BY WILLIAM HARWOOD STORY WRITTEN FOR CBS NEWS "SPACE PLACE" & USED WITH PERMISSION Posted: June 16, 2009 
Engineers pulled a protective gantry away from the shuttle Endeavour and restarted the orbiter's countdown Tuesday, setting the stage for launch Wednesday on a delayed space station assembly mission.
There are no technical problems of any significance and forecasters are predicting an 80 percent chance of good weather at launch time. Because of a conflict with NASA's Lunar Orbiter Reconnaissance mission, Endeavour's crew will only have one shot at getting off the pad. If the weather or some other problem delays launch, the shuttle team will stand down to give the LRO team a launch opportunity Friday at 6:41 p.m. Endeavour's normal launch window closes on June 20 and even if the LRO mission took off on time Friday, Endeavour would not get another launch opportunity until July 11, after a so-called "beta angle cutout" defined by the angle between the sun and the plane of the space station's orbit. During beta cutouts, temperature constraints can be violated when the shuttle is docked to the lab complex. Hoping for the best, engineers plan to begin loading a half-million gallons of liquid oxygen and liquid hydrogen rocket fuel into Endeavour's external tank starting with transfer line chill down at 8:15 p.m. The remotely-controlled fueling procedure should be complete by around 11:15 p.m. It was during fueling overnight last Friday that a significant leak showed up in an umbilical where a vent line attaches to the shuttle's external tank. The vent line is used to carry hydrogen gas from inside the tank to a flare stack well away from the shuttle where it can be safely burned away before launch. The leak occurred as the hydrogen section of the external tank was nearing a full load late Friday and the umbilical plate that connects the vent line to the side of the tank was subjected to extremely low temperatures. A similar problem grounded the shuttle Discovery for four days last March. Engineers are not sure what caused either problem, but in this case they suspect an internal seal might have been damaged when the umbilical was connected, disconnected and then reconnected when Endeavour was moved from pad 39B to 39A last month. In any case, the seal in question was replaced and engineers are hopeful the quick-disconnect fitting will be leak free the second time around. If all goes well, commander Mark Polansky, pilot Douglas Hurley, Canadian flight engineer Julie Payette, David Wolf, Christopher Cassidy, Thomas Marshburn and space station flight engineer Timothy Kopra will begin strapping in around 2:20 a.m. Wednesday to await liftoff. The goal of Endeavour's 16-day mission is to attach a sophisticated experiment platform to a Japanese research module, to replace aging solar array batteries, to store critical spare parts on the space station for future use and to replace one of the lab's six crew members. Kopra will remain behind aboard the station when Endeavour departs and Japanese astronaut Koichi Wakata, launched to the complex last March, will return to Earth in his place. Here is a timeline of major events in the shuttle's countdown to launch (in EDT): EDT...........EVENT Tue 06/16/09 01:15 PM......Resume countdown 01:45 PM......Pad clear of non-essential personnel 01:35 PM......Hydraulic power unit bite test 02:25 PM......Fuel cell activation 03:15 PM......Booster joint heater activation 03:45 PM......Master events controller test 04:00 PM......Tanking weather update 04:45 PM......Final fueling preps; launch area clear 05:15 PM......Red crew assembled 06:00 PM......Fuel cell integrity checks complete 06:15 PM......Begin 2-hour built-in hold (T-minus 6 hours) 06:25 PM......Safe-and-arm circuit test 06:45 PM......Crew wakeup 07:15 PM......External tank ready for loading 07:40 PM......Mission management team tanking meeting 07:45 PM......Crew medical checks 08:15 PM......Resume countdown (T-minus 6 hours) 08:15 PM......LO2, LH2 transfer line chill down 08:25 PM......Main propulsion system chill down 08:25 PM......LH2 slow fill 08:55 PM......LO2 slow fill 09:00 PM......Hydrogen engine cutoff sensors go wet 09:05 PM......LO2 fast fill 09:08 PM......Crew medical checks 09:15 PM......LH2 fast fill 11:10 PM......LH2 topping 11:15 PM......LH2 replenish 11:15 PM......LO2 replenish 11:15 PM......Begin 2-hour 30-minute built-in hold (T-minus 3 hours) 11:15 PM......Closeout crew to white room 11:15 PM......External tank in stable replenish mode 11:30 PM......Astronaut support personnel comm checks 11:55 PM......Crew photo op (recorded) Wed 06/17/09 12:00 AM......Pre-ingress switch reconfig 12:30 AM......NASA TV coverage begins 01:18 AM......Final crew weather briefing 01:28 AM......Crew suit up begins 01:45 AM......Resume countdown (T-minus 3 hours) 01:50 AM......Astronauts leave crew quarters 02:20 AM......Astronauts strap in 03:10 AM......Astronaut comm checks 03:35 AM......Hatch closure 04:05 AM......White room closeout 04:25 AM......Begin 10-minute built-in hold (T-minus 20m) 04:35 AM......NASA test director countdown briefing 04:35 AM......Resume countdown (T-minus 20m) 04:36 AM......Backup flight computer to OPS 1 04:40 AM......KSC area clear to launch 04:46 AM......Begin final built-in hold (T-minus 9m) 05:16 AM......NTD launch status verification 05:31:52 AM...Resume countdown (T-minus 9m) 05:33:22 AM...Orbiter access arm retraction 05:35:52 AM...Launch window opens 05:35:52 AM...Hydraulic power system (APU) start 05:35:57 AM...Terminate LO2 replenish 05:36:52 AM...Purge sequence 4 hydraulic test 05:36:52 AM...Guidance units to inertial 05:36:57 AM...Aerosurface confidence checks 05:37:22 AM...Main engine steering test 05:37:57 AM...LO2 tank pressurization 05:38:02 AM...Gaseous oxygen vent arm retraction 05:38:17 AM...Fuel cells to internal reactants 05:38:22 AM...Clear caution-and-warning memory 05:38:52 AM...Crew closes visors 05:38:55 AM...LH2 tank pressurization 05:40:02 AM...Orbiter to internal power 05:40:21 AM...Shuttle computers take control of countdown 05:40:31 AM...SRB steering test 05:40:45 AM...Main engine start (T-6.6 seconds) 05:40:52 AM...SRB ignition (LAUNCH)
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VIDEO:
SUNDAY'S UPDATE FROM MISSION MANAGEMENT TEAM 