The US space agency called off the launch minutes before the shuttle was due to blast off for the orbiting International Space Station, saying it would make another attempt tomorrow at 0510 GMT.
"We have a scrub for the day," said launch director Pete Nickolenko. "Unfortunately, the local weather has not cooperated." Cloud formations, storms and rain were within a 35-geometer radius of launch pad 39A at the Kennedy Space Center in Cape Canaveral, Florida. The weather unexpectedly worsened hours before the liftoff. It cleared minutes before the launchbut too late to give the all-clear.
The astronauts were onboard, along with a new bedroom, a treadmill, a freezer, food and other supplies Discovery is set to deliver during its 13-day mission.
It will also be dropping off the latest ISS residentUS astronaut Nicole Stott.
The delay was a reminder of the turbulence that surrounded the previous shuttle mission aboard the space shuttle Endeavour, which was postponed five times by weather woes and technical glitches.
Forecasters saw a 70% chance of favourable weather tomorrow, dropping to 60% on Thursday.