Next Shuttle Flight Could Slip Until April

NASA managers are assessing the danger if a tiny space shuttle engine valve were to crack and cause a leak of highly flammable gaseous hydrogen in the aft section of a space shuttle orbiter during ascent, and may slip the next shuttle mission until April.

One of the valves failed during the most recent flight, triggering an engineering investigation that could force a slip in the STS-119 mission to the International Space Station (ISS) until after the next Russian Soyuz mission to the orbiting outpost.

After a 13-hour flight readiness review (FRR) at Kennedy Space Center Feb. 20, associate administrator William Gerstenmaier gave the shuttle program until close of business Feb. 25 to lay out a plan for finishing the testing and analysis necessary to clear the flight. At issue is whether another valve failure would send a tiny piece hurtling into the plumbing that keeps the shuttle's main hydrogen tank pressurized with enough force to cause a potentially dangerous leak.

Also included will be an assessment of whether a leak would cause a dangerous hydrogen buildup in the orbiter's aft compartment -- information that was not available to participants in the Feb. 20 FRR, according to an agency spokesman.

Although the possibility of a valve failure apparently has existed since the first shuttle flight, new inspection and analysis tools indicate that the valve should be redesigned for safety. The upcoming work will determine if it is safe to keep flying with the existing design with inspection using the new tools.

Launch of the shuttle Discovery with the fourth and final U.S.-built solar array wing for the ISS had most recently been scheduled for Feb. 27, but that date will slip. The shuttle program needs to get the mission underway before about March 13 to avoid a conflict with the next Russian Soyuz mission to the ISS. After that date, the next time the shuttle could launch without a Soyuz conflict would be about April 7, Gerstenmaier said at a Kennedy Space Center press conference after the FRR.

John Shannon, the shuttle program manager, said most engineers participating in the flight readiness review believed it would be safe to fly on Feb. 27. But enough questions remained about the results of tests simulating the effects of a loose piece of the suspect valve in the orbiter end of the plumbing to warrant more work.

"I believe we'll be able to put a plan together and make sure we answer those questions before the new launch date," Shannon said. "We were not that far away."

Photo credit: NASA