The shuttle had survived so many incidents of tile damage that the risk seemed containable.

He said the tile damage posed no threat to the shuttle's return to the earth.

"They didn't seriously consider any of the outcomes beyond minor tile damage."

"Safe return indicated even with significant tile damage," the report concluded.

Despite the unknowns, the report concluded with the words, "safe return indicated even with significant tile damage."

"Any more activity today on the tile damage, or are people just relegated to crossing their fingers and hoping for the best?"

It suggests that somebody in your operation knew about extensive tile damage, wrote a memo two days before the accident.

Although other causes cannot be ruled out, tile damage remains a leading suspect in the loss of the craft.

To the data on tile damage, the scientists added temperature readings of where the shuttle tiles became hottest and were most likely to burn through.

In the past, astronauts have used cameras mounted on a robot arm to look for tile damage.