Bedeviled by the same hydrogen gas leak that postponed the space shuttle Endeavour's June 13 launch, NASA June 17 again scratched the 16-day mission to the International Space Station. The mission was officially called off at 1:55 a.m. EDT and rescheduled for July 11 at 7:39 p.m. EDT.
A hydrogen gas leak also delayed the March launch of Discovery by four days. NASA patched that leak at a vent line but the space agency still hasn't determined the exact source of the leak.
"We're going to step back and figure out what the problem is and go fix it," said Deputy Space Shuttle Program Manager LeRoy Cain during a briefing afterward. "Once we get it fixed and we're confident that we have a solution that's going to work and allow us to go fly safely, then we'll proceed forward."
Both the Endeavour and Discovery leaks will be evaluated in order to determine the cause. Data collected during fueling is expected to help the troubleshooting effort.
"This business that we're in is not for the faint of heart," Cain said at the briefing. "There are times when we don't get to go fly and that's fundamentally because it's not easy. Like problems we've had in the past, we'll get past this one as well and move forward."
NASA began filling Endeavour's fuel tank shortly after 8 p.m. June 16 but was forced to delay fueling operations due to storms in the area. After an almost three-hour delay, fueling began again to keep Endeavour on its launch schedule but then the gas problem resurfaced.
Via Twitter, Endeavour Commander Mark Polansky wrote, "It's a reminder that spaceflight is NOT routine. We will fly home to Houston this morning."
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 literal "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 unpressurized.
"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," Polansky said in a preflight interview.