I have no idea why the great one above could let trsgedies like this happen. You know it will be years before we truthfully know what really happened this morning. I am not anti-Government, but I dont think we will know for a while. I'm sure that they will take this into account with their other shuttles. The Columbia was over ten years old if I remember right. I think that this was the most used of all the shuttles, so imagine 10 years, lots of re entries around 12,000 mph.
God Bless the family and friends of the 7 astronauts.