RSS rollback, payload to the pad delayed at least 24 hours - Latest Nasa News

Last night, while venting shuttle Discovery's aft fuel propellant tanks in preparation for fuel loading, the Right Reaction Control System (RRCS) fuel helium tank pressure unexpectedly decreased in unison with the RRCS fuel propellant tank.

Troubleshooting overnight revealed at least one helium isolation valve that is leaking or is remaining in the open position when it is expected to be closed.

Following a review meeting this morning, engineers have decided to complete Orbital Maneuvering System (OMS) Reaction Control System fuel loading, Solid Rocket Booster Hydraulic Power Unit (HPU) tilt system and Auxiliary Power Unit (APU) hydrazine loads this weekend.

Engineers will meet again Monday morning to discuss options.

Currently, Rotating Service Structure (RSS) rotation will be delayed to no earlier than Tuesday, March 16; and payload delivery to the pad will be delayed to no earlier than Wednesday, March 17.

Launch still is targeted for April 5.

Space Shuttle Mission: STS-131

Image above: STS-131 Commander Alan Poindexter and Mission Specialist Dorothy Metcalf-Lindenburger prepare for take off in a NASA T-38 trainer jet. Image credit: NASA/JSC
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› Meet the STS-131 Crew

Discovery and Crew Prepare for STS-131 Mission
Commander Alan Poindexter is set to lead the STS-131 mission to the International Space Station aboard space shuttle Discovery. Joining Poindexter will be Pilot Jim Dutton and Mission Specialists Rick Mastracchio, Clay Anderson, Dorothy Metcalf-Lindenburger, Stephanie Wilson and Naoko Yamazaki of the Japan Aerospace Exploration Agency.

Discovery will carry a multi-purpose logistics module filled with science racks for the laboratories aboard the station. The mission has three planned spacewalks, with work to include replacing an ammonia tank assembly, retrieving a Japanese experiment from the station’s exterior, and switching out a rate gyro assembly on the S0 segment of the station’s truss structure.

STS-131 will be the 33rd shuttle mission to the station.