August 27, 2009

NASA again delays space shuttle launch

U.S. space agency managers have, for the fourth time, postponed the launch of space shuttle Discovery's STS-128 mission.

The NASA managers said they canceled Friday's 12:22 a.m. EDT scheduled liftoff to allow engineers more time to resolve an issue with a valve in the shuttle's main propulsion system.

The launch now is set for 11:59 p.m. Friday from NASA's Kennedy Space Center in Florida.

During loading of the shuttle's external fuel tank for Wednesday's launch attempt, a liquid hydrogen fill and drain valve located in Discovery's aft compartment failed to provide the proper indication when it was commanded to close, NASA said in a statement. Engineers cycled the valve five times Wednesday evening to collect data on the valve and its associated actuator and position indicator.

The NASA managers said they decided Thursday more time was needed to analyze the test data and develop alternative procedures for confirming that the valve is closed if the valve fails to provide the proper closed indication during Discovery's next launch attempt.

Discovery's 13-day mission to the International Space Station will deliver storage racks; materials and fluids science racks, a freezer to store research samples, a new sleeping compartment, an air purification system and a treadmill named after comedian Stephen Colbert.