Shuttle Endeavour launch no earlier than May 8
NASA’s flight rules require all three Auxiliary Power Units and heater circuits are operational for liftoff.
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NASA Headquarters, Washington, D.C. —
Published:
May 2, 2011 At NASA Kennedy Space Center's Launch Pad 39A, a technician makes his way across a platform in space shuttle Endeavour's aft section as work begins to remove and replace the aft load control assembly-2 (ALCA-2). NASA/Kim Shiflett
After Friday's launch scrub, Kennedy Space Center technicians searched for the cause of failure in a heater circuit associated with Endeavour's hydraulic power system. The failure was found in a power circuit in a switchbox in the shuttle's aft compartment.
Managers and engineers are developing a schedule to remove and replace the switchbox and retest the new unit. That work will delay Endeavour's launch until at least May 8.
The shuttle has three Auxiliary Power Units (APUs) that provide hydraulic power to steer the vehicle during ascent and entry. The hydrazine fuel lines on each APU have two heater circuits that prevent the fuel from freezing while the shuttle is in space. NASA’s launch commit criteria and flight rules require all three APUs and heater circuits are operational for liftoff.
Endeavour's six astronauts have returned to NASA's Johnson Space Center in Houston for several days of additional training.
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