"Accidents are things to be avoided. However, by the very nature of how we currently send humans into space and return them to Earth, there is a substantial amount of risk involved. Much of that risk has been identified and is manageable. But not all of it. Of course, when you hear this discussion, someone inevitably says that the only way to make these things risk free is not to do them.
Well, we have decided to do these risky things, now haven't we?"
The Columbia Report, Part 1, FreeSpace, Discovery News
The Columbia Report, Part 2, FreeSpace, Discovery News
NASA releases post-Columbia crew survival study, Spaceflight Now
NASA: Columbia crew equipment didn't work well, NewsDay
NASA to change spacecraft due to Columbia tragedy, Huntsville Times
New Report on 03 Disaster Details How Astronauts Died, NY Times
NASA faults equipment in Columbia shuttle disaster, CNN
Columbia crew had no chance, new NASA report says, Reuters
New Report Details Columbia Accident, Recommends Improvements, Universe Today
New NASA report details final minutes of Columbia, AP