NASA decided June 15 to postpone the launch of the Space Shuttle Endeavour to June 17. The original launch date for Endeavour's mission to the International Space Station was June 13, but a potentially dangerous hydrogen gas leak led NASA to scrub the takeoff.
The new launch forces NASA to reschedule the launch of a different mission set for June 17 to June 18, when an Atlas V rocket carrying the LRO (Lunar Reconnaissance Orbiter) and LCROSS (Lunar Crater Observation and Sensing Satellite) will launch.
Those plans, of course, are subject to weather conditions and the assumption that NASA will fix the hydrogen gas leak that delayed Endeavour's launch June 13. Forecasters are predicting a 70 percent chance of favorable launch conditions for Endeavour. If Endeavour doesn't launch before June 20, the mission will be delayed until July 11 because the late June and early July sun angle on the ISS would create heat-related difficulties for Endeavour.
The moon shot carrying the LRO and LCROSS is now also on a dicey deadline as it must launch by June 20 or wait until late June.
"A lot of things have to go our way," said Mission Management Team Chairman LeRoy Cain.
After calling off the launch, NASA began draining Endeavour's external fuel tank to investigate the leak. A hydrogen gas leak also delayed the March launch of Discovery by four days; NASA patched that leak at a vent line but still hasn't determined the exact source of the leak.
Launch Director Mike Leinbach said the Endeavour gas leak made the risk of a launch-pad explosion too high.
"There's no way we could have continued," Leinbach said at a June 13 news conference. "It's a commodity you just don't mess with."
Endeavour was scheduled to arrive at the ISS with a cargo bay full of work, including the final permanent components of the Japan Aerospace Exploration Agency's Kibo laboratory complex, a "front porch" on the ISS for space-exposed science experiments. To store and transport the experiments that the exposed facility will accommodate, Endeavour is also carrying a storage area similar to the logistics module on the Kibo laboratory, but not pressurized.
"It's a real exciting mission. We are the last mission that is taking up Japanese hardware on a space shuttle ... really big pieces of equipment that we're going to go ahead and leave behind on the space station for construction," Endeavour Commander Mark Polansky said in a preflight interview.