NASA Reviewing Images Of Jagged Area on Wing (washingtonpost.com)

High-resolution images taken by an Air Force camera show a jagged area on the leading edge of Columbia's left wing 60 seconds before the space shuttle broke apart over Texas last Saturday, Aviation Week and Space Technology magazine reported in its edition published today.

The damage seen in the photographs is in about the same area where a piece of insulating foam appeared to strike the leading edge of the wing after breaking off the shuttle's main tank at liftoff, but there was no indication last night that the impact caused the damage.

I have repeated stated that several pounds of stuff hitting the shuttle at over 500 miles an hour as NASA admits is probably going to be the ultimate cause. What happens after you have the damage gets more tricky to figure out as well as what exactly was damaged first.