KSC crews plan to replace Atlantis engine valve

NASA expects Atlantis to stay on track for a July 8 launch of the final shuttle mission while Kennedy Space Center crews replace a main engine fuel valve that failed during Wednesday's tanking test.

The valve replacement work will begin Monday and be completed within a week, including leak tests and closeout of the engine area, according to a KSC spokesperson.

The main fuel valve on one of three shuttle main engines showed low temperatures during the test, signaling a possible leak of liquid hydrogen. 

"We found a little bit of a leak in one area," astronaut Chris Ferguson, commander of the final mission, told reporters today at Mission Control in Houston after an ascent simulation. "We’re going to go back and fix that in the course of the normal flow. Hopefully it will preserve our current launch date."

The leak would have scrubbed a real countdown, disappointing hundreds of thousand of visitors expected to gather on the Space Coast for the launch.

Ferguson said the upcoming repair work at launch pad 39A was "living proof that we have the same capabilities we’ve always had" despite the loss of thousands of shuttle contractors in recent months or soon in layoff planned after Atlantis lands.

The four-person veteran crew of Atlantis -- also including pilot Doug Hurley and mission specialists Sandy Magnus and Rex Walheim -- will fly into Kennedy around Monday afternoon for training that culminates in a complete launch dress rehearsal Thursday.

An official launch date and time will be set during a flight readiness review scheduled June 28, just two days after the engine valve replacement work should be completed.

At the same time the valve work is going on, additional teams will be scanning support beams on the mid-section of Atlantis external tank to make sure there are no cracks, which was the purpose of this week's tanking test.

The launch processing schedule has several contingency days available over the July 4 holiday weekend to handle problems without delaying a July 8 launch.