Shuttle launch derailed again by hydrogen leak

Given the apparent severity of the problem and the planned launch of NASA's Lunar Reconnaissance Orbiter on Thursday or Friday atop an Atlas 5 rocket, Endeavour will be grounded until at least July 11 when the next shuttle/space station launch window opens.

"We've got to step back and try to understand this problem, and we will do that," said LeRoy Cain, chairman of NASA's Mission Management Team. "It's going to take us a little time...The team will be relentless in terms of trying to go understand what's going on with this system. We'll fix it and we'll move forward once we have determined we can get in a safe configuration to go fly."

The vent line in question, attached to the side of the shuttle's external fuel tank, carries hydrogen gas away from the shuttle so it can be safely dissipated. A leak in the same mechanism scrubbed a launch attempt on Saturday.