NASA called off the launch of space shuttle Discovery on Tuesday, the second day in a row the liftoff was scrubbed, this time because of a bad fuel valve.
Launch officials halted the countdown midway through the fueling process. The seven astronauts had not yet boarded the shuttle for the scheduled early Wednesday morning flight to the international space station.
A new launch date was not immediately set. It was also unclear whether NASA would be able to meet the end-of-month deadline for sending Discovery on its way. Over the weekend, managers said if Discovery was not flying by Aug. 30 or so, the flight almost certainly would slide into October because of a pair of upcoming launches to the space station from Japan and Russia.
The problem cropped up while engineers were trying to open and shut the fill-and-drain valve in Discovery's engine compartment. It appeared to be broken, said NASA spokesman Allard Beutel. He stressed that the exact condition of the valve was not known; it could be sticky.