WASHINGTON -- NASA will hold a news conference Friday, Feb. 20, following a review of space shuttle Discovery's readiness for flight and an assessment of shuttle flow control valve testing. An official launch date for the STS-119 mission has not been set, but for planning purposes, liftoff now is targeted for no earlier than Feb. 27.

The new planning date is not expected to affect the launch dates for missions that will follow Discovery's flight, STS-125 to NASA’s Hubble Space Telescope and STS-127 to the International Space Station.

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

NASA Television and the agency's Web site will broadcast the Feb. 20 briefing live. Media may ask questions from participating NASA locations. Reporters should contact their preferred NASA center to confirm its participation. The news conference will begin no earlier than 5 p.m. EST at NASA's Kennedy Space Center in Florida.

The briefing participants are:

- Associate Administrator for Space Operations Bill Gerstenmaier
- Space Shuttle Program Manager John Shannon
- Space Shuttle Launch Director Mike Leinbach

For NASA TV streaming video, downlink and scheduling information, visit:

http://www.nasa.gov/ntv

For STS-119 crew and mission information, visit:

http://www.nasa.gov/shuttle