News From Space!

NASA mission managers, after a marathon Flight Readiness Review meeting, have delayed the launch of Shuttle Discovery for a fourth time, due to safety concerns about the Shuttle's fuel system. 

Each Space Shuttle Main Engine has a pop-up valve, called a Flow Control Valve or FCV, which regulates the flow of hydrogen gas between the SSMEs and the huge External Tank. The tank need to be kept at a constant pressure as the liquid hydrogen fuel drains during launch, and the FCVs help do that.

On the last Shuttle flight, STS-126, it was discovered that one of the FCVs failed during Endeavour's launch. While no harm was done to that mission, a similar failure could doom the spacecraft and crew, so NASA wants to get to the bottom of the FCV issue before authorizing any more flights. This leaves Discovery's STS-119 liftoff, which was last scheduled for Feb 27th, with no new date. NASA reports:

NASA Defers Setting Next Shuttle Launch Date

Image: On Launch Pad 39A at NASA's Kennedy Space Center in Florida, STS-119 crew members get a close look at the docking adapter installed in space shuttle Discovery's payload bay. Photo credit: NASA/Kim Shiflett
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During a thorough review of space shuttle Discovery's readiness for flight, NASA managers decided Friday more data and possible testing are required before proceeding to launch. Engineering teams have been working to identify what caused damage to a flow control valve on shuttle Endeavour during its November 2008 flight.

"We need to complete more work to have a better understanding before flying," said Bill Gerstenmaier, associate administrator for Space Operations at NASA Headquarters in Washington. Gerstenmaier chaired Friday's Flight Readiness Review.

"We were not driven by schedule pressure and did the right thing. When we fly, we want to do so with full confidence."

The shuttle has three flow control valves that channel gaseous hydrogen from the main engines to the external fuel tank. Teams also have tried to determine the consequences if a valve piece were to break off and strike part of the shuttle and external fuel tank.

The Space Shuttle Program has been asked to develop a plan to inspect additional valves similar to those installed on Discovery. This plan will be reviewed during a meeting on Wednesday, Feb. 25. Afterward, the setting of a new target launch date may be considered.

Additional Resources
› STS-119 Flow Valve Fact Sheet (447 Kb PDF)
› STS-119 Mission Summary (562 Kb PDF)
› STS-119 Fact Sheet (788 Kb PDF)
› STS-119 Press Kit (5.06 Mb PDF)
› STS-119 Information for Educators

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Preflight pics are up at the JSC Gallery. More preflight pics and video at KSC. Discussion here. Check the links at right for play-by-play and NASA TV.