On Tuesday, a parade of NASA officials are scheduled to testify about the internal investigation before the separate Columbia Accident Investigation Board.
NASA and the Columbia board have conducted parallel inquiries into the accident, but far more is known about the independent board's probe because of its consistent effort to inform the public via regular hearings and news briefings.
NASA, by contrast, has been wary of releasing information without routing it through the outside investigation board. The internal investigation, led by David Whittle, is focused sharply on technical issues and moving forward mostly out of public view.
The NASA witnesses, appearing at what may be the board's final public hearing, plan to introduce a new timeline of events during the final minutes of Columbia's flight and "we're going to try to discuss some of the conclusions that lead us to believe that we violated the wing leading edge and that propagated into failure of the wing," the NASA manager said.
The acknowledgement is the strongest yet from NASA. The agency cautioned and even chastised reporters and others about jumping to the conclusion that the debris seen hitting the left wing 81 seconds after blast off had anything to do with the disaster. As Columbia orbited Earth, NASA and its contractors studied video of the debris strike and determined the heat shield would hold up.
A little over three months after the accident, there's little evidence to contradict the cause is not related to the debris hit captured on launch day films.
The final confirming proof could come from air canon tests being developed at Southwest Research Institute in Texas. Ongoing canon tests are setting the stage for climactic experiments, perhaps a month from now, in which a 2.5 piece of tank foam is to be fired at a custom-made space shuttle wing. A wing off the shuttle Enterprise, a test vehicle never flown in space, will be equipped with reinforced carbon panels and other heat shield components taken off orbiters that have flown in space.
"We're pretty sure it was the foam, but we'd like to do the foam testing and confirm that that size a chunk of foam can break" the heat shield parts, the NASA manager said. "If we do that, everybody will say it's the foam."
NASA already is working on fixes to keep the foam from coming off the external tank, a phenomenon shuttle engineers dismissed as a maintenance headache rather than a safety issue.
A study of NASA documents and photographs by Florida Today showed that foam came off the fuel tank on at least 71 missions to date and debris of some kind battered the ships during every launch since the program began in 1981 -- despite design requirements that say the orbiter's delicate heat-shield tiles should not be hit by anything.
NASA has made minor improvements to reduce foam shedding over the years, but never solved the problem. More than 20 years of ships returning home safely despite damaged tiles, and inconsistent tracking of the problems, colored managers' decision to accept the risk over the years, continue flying and ultimately to determine Columbia was OK too.
NASA witnesses Tuesday include David Whittle, who heads the agency's Mishap Investigation Team. One non-NASA witness will be Dr. Brian Kent, of the Air Force Research Laboratory, who has used radar technology to study the mystery object that floated away from Columbia on its second day in orbit. The radar tests match up best with components that fit the foam conclusion, such as part of one of the leading edge heat shield panels or half of a seal that fits between those panels on the front of the wing.
"What they've learned is not definitive, but it still points in the direction of the scenario we're going to talk about," the NASA manager said. "They've been able to rule out a bunch of things; that's at least been helpful."
Published under license from FLORIDA TODAY. Copyright 2003 FLORIDA TODAY. No portion of this material may be reproduced in any way without the written consent of FLORIDA TODAY.
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