NASA fueled space shuttle Discovery at the launch pad Friday, not for flight but rather for testing to understand the mysterious cracking that occurred last month. Discovery is grounded until at least the beginning of February because of potentially dangerous cracks that occurred in the fuel tank during an actual launch attempt, AP reported. The cracks have been fixed, but engineers still do not understand why they happened. So in a countdown test that began at sunrise, the launch team pumped more than 500,000 gallons (1.9 million liters) of liquid hydrogen and oxygen into Discovery's external fuel tank. The tank was rigged with sensors and other equipment. Whenever Discovery does fly, it will be its last trip into orbit and one of the final two or three shuttle missions remaining. It's loaded with supplies for the International Space Station as well as an experimental humanoid robot. «We're not committing to flying anytime soon. We've got to wait until we know we have a good answer to go fly,» launch manager Mike Moses said as Discovery's 15-story tank filled up. «We want to make sure we know the risk we have in front of us.» The concern is that any cracks in the brackets could cause chunks of foam to pop off and, in the worst case, slam into the Discovery at liftoff. A large slab of foam doomed space shuttle Columbia in 2003.
