The space shuttle Discovery's mission to the International Space Station, due to launch on February 12, has again been postponed for the third time late Friday by NASA. The official launch date for space shuttle has not been disclosed yet as the completion of ongoing fuel valve tests may take some time. However, the shuttle is unlikely to launch before February 27 as per NASA spokesperson. NASA would hold a press conference on February 20 to explain the progress of work.

NASA is reviewing Discovery's readiness for flight, keeping in view all technicalities including flow control, control valve testing, internal resistance the instant temperature changes. The space shuttle has three valves to supply hydrogen from the main engines to the external fuel tank.

NASA's specialist teams are analyzing the causes that damage the flow control valve in shuttle, Endeavor, in November. The team is taking all possible precautionary steps by removing, inspecting and reinstalling the valves to avoid any adverse eventuality.

Discovery will carry a replacement distillation assembly to improve the water recycling system of space station besides completing other tasks such as Space Station's fourth and final set of solar arrays and repair of laboratory's truss.