Just watched a heartbreaking and wrenching moment in the NASA news conference, just before 4 PM EST. Ron Dittemore, Shuttle Program Manager, was asked about the piece of insulating foam that apparently struck the shuttle's left wing on take-off. It now seems that what few sensor readings went off-line just before the accident were also on the left wing. (Whether there's a connection is, at least at this point, entirely speculative.) Dittemore was asked about whether that was the problem, why more wasn't done, etc.

Dittemore laboriously and seemingly convincingly went through what they'd done. They looked at the data. They called together the experts. They went over earlier experience. They went over everything. Taking that all together, they decided it didn't represent a problem.

His voice resonated with 'We did everything we should have done.' And yet, as he worked his way through the explanation, you could see in his occasionally-tightened face 'What did we miss?'

No real comment. Certainly, no criticism. Just one of those agonizingly human moments where the look on the face says everything.