Briefing Upcoming About Launch Postponement

NASA TV will air a news conference about today's shuttle launch postponement at about 4 p.m. EDT. �The participants will be shuttle Launch Integration Manager Mike Moses and STS-128 Launch Director Pete Nickolenko.

NASA managers postponed Friday's 12:22 a.m. EDT launch of space shuttle Discovery to allow engineers more time to develop plans for resolving an issue with a valve in the shuttle's main propulsion system. Launch now is targeted for no earlier than 11:59 p.m. Friday, Aug. 28, 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. Engineers cycled the valve five times Wednesday evening to collect data on the valve and its associated actuator and position indicator.

NASA managers decided Thursday that more time is 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.