spacetoday.net: Countdown begins again for shuttle launch

Posted: Sat, May 14, 2011, 8:44 AM ET (1244 GMT)
STS-134: shuttle on pad at night (NASA/KSC)

NASA started countdown clocks on Friday for Monday morning's scheduled launch of the space shuttle Endeavour on that orbiter's final mission. Countdown clocks started at 7 am EDT (1100 GMT) Friday for the launch, scheduled for 8:56 am EDT (1256 GMT) Monday from the Kennedy Space Center in Florida. The launch was previous scheduled for April 29, but scrubbed a few hours before the scheduled liftoff time when heaters in a hydrazine fuel line in one of the orbiter's three auxiliary power units failed to turn on. Technicians replaced a power switching box linked to the failure and successfully retested the system, although engineers were not able to conclusively identify the root cause of the problem. Forecasts call for a 70 percent chance of acceptable weather at launch.