The delay came because of a broken fuel tank sensor. The sensor showed a low level of fuel in one of the tanks even though it was completely full. NASA officials did not say when they would reschedule the launch.
Officials and technicians have been working around the clock to ensure Discovery's safe voyage. As late as Tuesday, however, minor technical problems plagued the shuttle, which is waiting on its launchpad at Kennedy Space Center, in Florida.
On Tuesday afternoon, a cockpit window cover fell off and damaged two protective tiles at the tail of the spacecraft. The cover is used to protect the windows of the shuttle before it takes off. As it fell, it knocked into tiles meant to protect the shuttle from overheating.
Technicians replaced the tiles and officials said there was no need to delay the launch.
The Discovery has a limited window in which to launch to reach the International Space Station. The window closes on July 31. The next chance will not be until September. In space, crewmembers will deliver badly needed supplies and test new ways of finding shuttle damage and repairing it while in orbit around the earth.
"Can there be something that we don't know about that can hit us? Yeah. This is a very tough business," NASA administrator Michael Griffin said. "But everything we know about has been covered."
Discovery specialists Charles Camarda, Wendy Lawrence, Soichi Noguchi, Steve Robinson, and Andrew Thomas. Commander Eileen Collinswhom they all call "Mom"leads the crew.
Collins first became an astronaut in 1991 after several years in the U.S. Air Force. She was named commander of the Discovery in 1999.
"I will be back after a 12-day mission." Collins said she told her daughter. "I'm doing this mission because this is something I believe in and we need to carry on the mission of the Columbia crew."