spacetoday.net: March 12 date set for shuttle launch

Posted: Thu, Feb 26, 2009, 6:37 AM ET (1137 GMT)

NASA is tentatively planning to launch the space shuttle Discovery on the STS-119 mission to the ISS, a date that gives the agency little room for additional delays before having to postpone the mission until April. Shuttle managers set the date after making the decision to replace three flow control valves in the shuttle's main engines the regulate the flow of gaseous hydrogen with versions that have flown fewer times. Engineers had raised concerns about fatigue causing cracks in the valves, which could create debris that could cause additional damage to the engines during launch. The launch had been scheduled for exactly one month earlier, February 12, but delayed several times while the issues with the valves was studied; the most recent delay came Friday night after a lengthy flight readiness review. NASA has until only about mid=March to launch the shuttle so that it can complete its mission at the ISS before a Soyuz spacecraft arrives at the station. If the mission can't be launched by then NASA would have to wait until after the Soyuz mission around April 7 to try again.