WASHINGTON – A NASA engineer whose e-mails led to a furious internal debate about Columbia's safety felt lingering uneasiness moments before the fiery disaster but was confident the shuttle would land safely, he said Monday in his first public remarks since the accident.
Robert Daugherty's comments supported NASA's position since the Feb. 1 accident, that a clutch of midlevel engineers across three states never believed the shuttle was threatened but had engaged in cautionary analyses days before the accident to consider problems with insulating tiles that might have been damaged on liftoff.
Daugherty's e-mails led to a flurry of messages and telephone calls that ultimately described with eerie precision what investigators believe probably happened aboard Columbia: searing temperatures penetrating the stricken shuttle's left wing and melting it from the inside.
The messages never were passed to senior NASA officials, but Daugherty said his e-mails were handled appropriately.
"My e-mail was technical issues that I intended to have technical people discuss, and that's exactly what happened," Daugherty said. "In my estimation, it went exactly where I intended it and exactly where I thought it should be."
Daugherty has emerged as the focus for questions about how seriously engineers believed Columbia might have been doomed, in part because of blunt language in some e-mails. In one message four days before the accident, Daugherty questioned whether officials were "just relegated to crossing their fingers and hoping for the best."
In another, Daugherty expressed frustration that "getting information is being treated like the plague" and that some NASA experts described the shuttle's chances as "survivable but marginal."
Daugherty said Monday his colorful language was part of the culture of e-mail, where people are less careful about their words. "It was the way I talked to my engineering buddies," he said. "I understand the difficulty in interpreting that. That's why we are talking today to clear that up as best we can."
Daugherty said he used the plague analogy solely to express frustration with being unable immediately to run computer tests to simulate shuttle landings with flat tires, not as a comment about the broader exchange of information within NASA.
"As with any engineer who wants information, we always think what we want is the most important thing," he said. "I was impatient to get things done and some of that impatience came out in the e-mails, but it wasn't concern because I felt there were any real problems."
Daugherty and a supervisor, Mark Shuart, spoke with reporters in a conference call organized by NASA, with staff from the agency's headquarters in Washington listening. The two previously had declined to talk about the e-mails, citing the investigation by the board looking into the accident. They said Monday the board indicated that speaking with reporters wouldn't hamper the probe.
Daugherty recounted driving to his office at NASA's Langley research facility in Hampton, Va., the morning of Columbia's fateful return, arriving just before 9 a.m. That was minutes after investigators believe the shuttle began shedding pieces over the Southwest during its fiery re-entry through earth's atmosphere.
"I'd been absorbed in `what-if'ing' all week, so there was some natural uneasiness on my part," Daugherty said, remembering watching the drama unfold on NASA's internal television system. "But I certainly believed everything was going to be perfectly fine."
Daugherty said he realized things were terribly wrong after flight controllers in Houston kept performing communications checks, trying in vain to contact Columbia's crew.
By the time radar sites failed to locate the inbound shuttle, Daugherty knew all was lost. He quickly recalled the debate inside NASA during the preceding days about how damage from extreme heat inside the shuttle's wheel compartment and left wing could prove catastrophic.
"That is the first thing that ran through my mind, hoping something like that had not occurred," he said. He described that morning as "a troubling time."
NASA for weeks has maintained, and Daugherty largely agreed, that engineers were confident in assurances by the Boeing Co., a contractor, that possible damage to Columbia's insulating tiles wouldn't prevent its safe return.
Daugherty said that he did not know whether the Boeing analysis on Columbia's thermal systems was right or wrong and that he did not see it until Jan. 27, days after it was presented to mission controllers in Houston.
"We all absolutely agreed that there was no expectation of anything bad happening during the landing," he said.
Daugherty said he agreed in a phone call that day with a NASA colleague, Carlisle Campbell of Johnson Space Center, to "play devil's advocate" and to consider problems the shuttle might encounter if the Boeing analysis should prove wrong. Both men were considered top experts within the agency on the shuttle's landing gear.