Interesting-I just heard about it on the news. Pieces of insulation from the tank have fallen on the shuttle in 9 previous flights-6 times of which it happened to Columbia. My guess is, this ship had some vibration problems. Probably increased the fatigue on its structure, and the result is today's tragedy.
40% of the STS fleet lost in catastrophic accidents. only 3 shuttles left. No plans to build a new shuttle.A new spacecraft that would replace the shuttle- it would take 10-15 years. I'm sorry to say it, but I feel very disilusioned about the state of the space program.
If bureaucracy and shoe-string budget continue to plague NASA, I'm afraid those seven people died in vain