February 21, 2009
NASA launch remains uncertain
The space shuttle Discovery's launch date remains uncertain, said NASA officials at Kennedy Space Center in Orlando, Fla.
USA Today reported Saturday that National Aeronautics and Space Administration officials cannot agree on whether to launch the shuttle Friday, as tentatively planned, or wait until mid-March.
The newspaper reported there are concerns about a critical set of valves on the shuttle that have repeatedly delayed the flight from its original Feb. 12 target date. The three valves regulate the flow hydrogen gas from each of the shuttle's main engines to its 15-story external tank.
The valves allow the tank to maintain proper pressure as liquid hydrogen propellant is burned during the 8.5-minute climb to orbit. If pressure rises too high or sinks too low, or if a broken valve punctures the gas line, the results could be deadly, the newspaper noted.
Seven astronauts are to ride the Discovery into space to install the International Space Station's final set of American solar array wings, completing its power supply.