CAPE CANAVERAL, Fla. -- During a review of space shuttle Discovery's readiness for flight, NASA managers decided Tuesday to plan a launch no earlier than Feb. 19. The new planning date is pending additional analysis and particle impact testing associated with a flow control valve in the shuttle's main engines.

Discovery's STS-119 mission to the International Space Station originally had been targeted for Feb. 12.

The valve is one of three that channels gaseous hydrogen from the engines to the external fuel tank. One of these valves in shuttle Endeavour was found to be damaged after its mission in November. As a precaution, Discovery's valves were removed, inspected and reinstalled.

The Space Shuttle Program will convene a meeting on Feb. 10 to assess the analysis. On Feb. 12, NASA managers and contractors will finalize the flight readiness review, which began Tuesday, to address the flow control valve issue and to select an official launch date.

The 14-day mission will deliver the station's fourth and final set of solar arrays, completing the orbiting laboratory's truss, or backbone. The arrays will provide the electricity to fully power science experiments and support the station's expanded crew of six in May. Altogether, the station's 240-foot-long arrays can generate as much as 120 kilowatts of usable electricity -- enough to provide about forty-two 2,800-square-foot homes with power.

Discovery also will carry a replacement distillation assembly for the station's new water recycling system. The unit is part of the Urine Processing Assembly that removes impurities from urine in an early stage of the recycling process. The Water Recovery System was delivered and installed during the STS-126 mission in November, but the unit failed after Endeavour's departure.

Joining Archambault on STS-119 will be Pilot Tony Antonelli and Mission Specialists Joseph Acaba, Richard Arnold, John Phillips, Steve Swanson and Japan Aerospace Exploration Agency astronaut Koichi Wakata. Wakata will replace Sandra Magnus aboard the station. She will return home with the Discovery crew after three months in space.

Former science teachers Acaba and Arnold are now fully-trained NASA astronauts. They will make their first journey to orbit on the mission and step outside the station to conduct critical spacewalking tasks.

STS-119 will be Discovery's 36th mission and the 28th shuttle flight dedicated to station assembly and maintenance.

For more information about the STS-119 mission, including images and interviews, visit:

http://www.nasa.gov/shuttle