Endeavour at dawn on Friday. Photo Credit/NASA TV

FRIDAY UPDATE:

Endeavour’s lift off,  planned for Friday at 3:47 p.m., EDT, was scrubbed by an undiagnosed problem with a hydraulic system heater.

The launching has been postponed by at least three days or until May 2.

NASA Launch Director Mike Leinbach and Mission Management Team members were meeting Friday afternoon to refine a troubleshooting strategy.

The May 2 launch window opens at 2:33 p.m., EDT.

Endeavour astronauts Mark Kelly, Greg H. Johnson, Mike Fincke, Greg Chamitoff, Drew Feustel and Roberto Vittori of the European Space Agency were being chauffeured to Launch Pad 39A at the Kennedy Space Center, when the launch control team determined that one and possibly two heaters on an Auxiliary Power Unit fuel line had failed and that no work around was possible.

 

  Just before dawn Friday,  NASA Mission Managers declared shuttle Endeavour still “Go” for launch at 3:47 p.m., EDT, after a night of stormy weather at the Kennedy Space Center.

The latest weather outlook calls for a 70 percent chance of favorable conditions. Low clouds could be a factor.

Shuttle commander Mark Kelly, pilot Greg H. Johnson and mission specialists Mike Fincke, Drew Feustel, Greg Chamitoff and Roberto Vittori of the European Space Agency are scheduled to begin boarding Endeavour at 12:30 p.m.

Endeavour will head for the International Space Station with a cargo that includes the Alpha Magnetic Spectrometer and external spare parts. Four spacewalks are planned.

The AMS, a particle detector, could help the global physics community address the mysteries of anti-matter and dark matter.

Endeavour’s pre-retirement mission, her 25th, is expected to span 14 to 16 days.