NASA has delayed the launch of the space shuttle Discovery for a fourth time amidst concerns about valves.

After meeting all Friday at Kennedy Space Center in Florida, shuttle managers decided against launching in a week. The launch date for Discovery currently is "under review," NASA said in a statement. The launch had been targeted for no sooner than Feb. 27.

Three valves in each shuttle channel hydrogen gas from the main engines to the external fuel tank. Discovery's valves were removed, inspected and reinstalled as a precaution after one valve on the shuttle Endeavor broke during its November mission.

Managers want to make sure if that happens again, the shuttle and its seven-man crew would be safe.


The space shuttle Discovery lands, ending Mission STS-124 to the International Space Station, at the Kennedy Space Center in Cape Canaveral, Florida June 14, 2008.(Xinhua/Reuters File Photo)
Discovery's latest mission to the International Space Station originally had been scheduled for Feb. 12. During a review of Discovery's readiness for flight, NASA managers decided Feb. 3 to plan a launch no earlier than Feb. 19.

However, on Feb. 7, NASA announced that the launch would be no earlier than Feb. 22, citing concerns over a valve that keeps fuel flowing in Discovery's main engines. NASA announced last Friday that Discovery's liftoff was targeted for no earlier than Feb. 27.

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 shuttle also will carry a replace distillation assembly for the station's new water recycling system.

Source: Xinhua