Some Progress Seen In Understanding Flow Control Valves Problem: NASA

Continuing worries about flow control valves on Space Shuttle Discovery once again caused NASA to postpone its launch, now set for no earlier than Feb. 27, the space agency announced.

Further details may become clear at the end of the work week, when top NASA officials will hold another flight readiness review for the shuttle, followed by a news conference beginning no earlier than 5 p.m. ET Friday.

At this point, launch dates for other future missions aren’t expected to be affected by the further delay in the Discovery liftoff, which has been postponed repeatedly from an earlier Feb. 12 launch date, as NASA and contractor experts wrestle with the flow control valves problem. (Please see Space & Missile Defense Report, Monday, Feb. 9, 2009. Also, please see launch schedule in this issue for a listing of later missions.)

The new Discovery flight date isn’t expected to affect the May 12 Space Shuttle Atlantis STS-125 Mission to repair and refurbish the Hubble Space Telescope, or the subsequent flight of Space Shuttle Endeavour on the STS-127 Mission to continue construction of the International Space Station.

For now, experts continue to probe whether part of one of the flow control valves on Discovery could break off and accelerate under high pressure to damage plumbing in the fuel system.

Teams from multiple NASA centers and contractor sites have made significant progress in understanding what caused the damage to a flow control valve in shuttle Endeavour during its mission in November, according to NASA.

There are three valves in each shuttle that channel gaseous hydrogen from the main engines to the external fuel tank.

Engineering teams have performed a tremendous amount of work, including computer modeling and actual tests to determine the consequences if a piece of a valve were to break off and strike shuttle and external fuel tank components.

More time was needed to complete analyses and testing necessary to fly safely, causing the repeated delays.