The space shuttle Columbia, with 7 crew aboard, has been lost over Texas. It broke up while coming in to land. Very sad news indeed.
It appears that there was a small problem at take off that may suggest a reason for the accident. Spaceflightnow.com says
During a mission status news conference yesterday, Entry Flight Director Leroy Cain was asked about any possible damage to the shuttle’s thermal tiles during launch. The tiles are what protect the shuttle during the fiery reentry into Earth’s atmosphere.
Tracking video of launch shows what appears to be a piece of foam insulation from the shuttle’s external tank falling away during ascent and hitting the shuttle’s left wing near its leading edge.
But Cain said engineers “took a very thorough look at the situation with the tile on the left wing and we have no concerns whatsoever. We haven’t changed anything with respect to our trajectory design. It will be a nominal, standard trajectory.