Wednesday's launch of the space shuttle Discovery has been called off because of a faulty fuel-tank sensor.
Discovery was supposed to blast off from Florida for the first shuttle flight since the Columbia disaster two and a half years ago. The crew of seven was already on board when the launch was scrubbed.
No new launch date has been set. Launch control says it will take some time to figure out the problem with one of the four engine cut-off sensors, which are responsible for making sure the shuttle's engines shut down at the proper point during the ascent. NASA says it appeared the sensor was showing a low fuel level, even though the tank is full.
As part of the mission, Discovery is supposed to bring supplies to the international space station and test new techniques for inspecting and patching the shuttle in orbit.
Earlier Wednesday, weather had been considered NASA's primary concern, with just a 40 percent chance it would be acceptable.