The Columbia Accident Investigation Board (CAIB) has said it believes that a breach of some kind in Columbias left wing touched off a chain of events that resulted in the shuttle breaking up over the western United States on the morning of Feb.1.

Daughertys e-mails detailed what he prefaced as worst case scenarios and included his complaints about the difficulty he was having getting Ames Research Center in Mountain View, Calif. to simulate a space shuttle approach and landing with two flat tires. The e-mails have been cited frequently by some media organizations as proof that at least some people inside NASA knew of the danger Columbia and her crew faced that morning.

Daugherty himself admitted to reporters that he felt some uneasiness that morning as he drove to Langley to watch the Columbia landing on NASA TV.

But he said his uneasiness was not a fear that Columbia would not make it to the runway.

I had spent the week talking about bad thing, doing all this what iff-ing, he said. The amount of damage [caused by the external tank foam striking Columbia during launch] was in some respects was unknown and that, combined with talking about all these scenarios all week long with colleagues, just sort of gets your gain up a bit and that naturally leaves some uneasiness.

In a series of e-mails exchanged with colleagues at Langley and Johnson Space Center in Houston during the final few days of Columbias 16-day research mission, Daugherty wrote that if the shuttles wheel well had been breached, mission control would have to be prepared to land Columbia without working landing gear or order the crew to attempt a bail out.

Daugherty said that as it became clear that Columbia was lost, he immediately thought of the breached wheel well scenario.

Certainly thats the first thing that ran through my mind and I was certainly hoping something like that had not occurred, he said. And of course we still dont know.

Daugherty, an expert on the shuttle landing gear system, told colleagues during the mission he thought NASA should order spacewalks or the telescopic observation of the shuttle, to find out more about any tile damage Columbia might have experienced. He stressed to reporters that he was not an expert in those fields, nor a tile expert.

NASA officials have said repeatedly since the Columbia accident that the agency did not formally request imagery from the U.S. Air Force because past experience revealed that such imagery was too grainy to be of much help. NASA officials have also defended their decision not to order a spacewalk inspection of the damage, pointing out the Columbias crew was not equipped for such a procedure.

Daugherty said he feels his e-mails received the proper attention by the appropriate people, but he was surprised by how much attention they received since the accident and that he was frustrated that they were misinterpreted. He hoped the teleconference with reporters would help clear the air and put into context a number of his more oft quoted remarks.

Daugherty said his remark that getting information is being treated like the Plague was not an assessment of NASA in general, but a colorful description about his frustrated attempts to get Ames to interrupt astronaut training to simulate his failed landing gear scenario.

All I can say is it was just the sort of way I talk with my engineering buddies, he said. I understand the difficulty of interpreting that [remark]. Thats why we are talking today, to try to clear that up as best we can.

He said the remark betrays his own impatience and he did not blame Ames for not breaking its training schedule to run an unapproved simulation.