NASA Resets Shuttle Endeavour's Launch for No Earlier Than May 2
The shuttle has three Auxiliary Power Units (APUs) that provide hydraulic power to steer the vehicle during ascent and entry. NASA launch commit criteria and flight rules require all three APUs to be fully operational for launch.
Endeavour's external fuel tank was drained of more than 500,000 gallons of liquid hydrogen and oxygen so engineers can access the area Saturday and evaluate the issue with APU 1.
For the latest information about the STS-134 mission and its crew, visit: