Space shuttle Discovery launch cancelled

Space shuttle Discovery readies for launch, which was scheduled for Wednesday night.
The planned Wednesday night launch of space shuttle Discovery has been cancelled due to an apparent leak in the giant external fuel tank, the Kennedy Space Center said.

The decision is the latest in a series of delays for the NASA shuttle mission. In total, the mission has been delayed for more than a month. A Twitter message from NASA says the Discovery launch may be tried again on Thursday at 8:54 p.m. Cmdr. Lee Archambault and his six crewmates had been scheduled to lift off at 9:20 p.m. The two-week mission was supposed to visit the International Space Station It was to be NASA’s 28th shuttle mission to the space station. The launch date had been delayed previously to allow “additional analysis and particle impact testing associated with a flow-control valve in the shuttle’s main engines,” the agency said last week. According to NASA, the readiness review was ordered after damage was found in a valve on the space shuttle Endeavor during its November 2008 flight. Three valves were cleared and installed on Discovery, NASA said. Discovery is to deliver the fourth and final set of “solar array wings” to the space station. With the completed array, the station is expected to be able to provide enough electricity when the crew size is doubled to six in May, NASA said. The Discovery also will carry a replacement for a failed unit in a system that converts urine to drinkable water, it said. Discovery’s 14-day mission was supposed to include four spacewalks. There are nine shuttle flights scheduled before NASA retires the three space shuttles in 2010. Eight missions are slated to complete the construction of the international space station, and one is dedicated to maintenance and upgrades to the Hubble Space Telescope.