An official launch date for the STS-119 mission has not been set. For planning purposes only, the liftoff now is targeted for no earlier than February 27th, according to a statement from NASA. 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 uncovering the cause for the damage to a flow control valve in shuttle Endeavour that occurred during its mission last November. Discovery's valves were removed, inspected, and reinstalled as a precaution, after one valve in shuttle Endeavor had been found damaged. There are three valves in each shuttle that channel gaseous hydrogen from the main engines to the external fuel tank. Discovery's latest mission to the International Space Station had originally been scheduled for February 12th. During a review of Discovery's readiness for flight, NASA managers decided on Feb. 3 to plan a launch no earlier than February 19th. However, on February 7th, NASA announced the launch of Discovery will be no earlier than Feb. 22, citing concerns over a valve that keeps fuel flowing in Discovery's main engines.
Discovery's 14-day mission will deliver the International Space Station's fourth and final set of solar arrays, completing the orbiting laboratory's truss, or backbone. The arrays will provide 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 — that's enough to provide power to 42 homes of 2,800 square feet. Discovery will also carry a replacement distillation assembly for the station's new water recycling system.