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Columbia heat vortex { March 8 2003 } Original Source Link: (May no longer be active)
http://www.washingtonpost.com/wp-dyn/articles/A59209-2003Mar7.htmlhttp://www.washingtonpost.com/wp-dyn/articles/A59209-2003Mar7.html
Photo of Columbia Yields New Clues
Image May Indicate Multiple Heat-Shield Panels Came off Left Wing
By Kathy Sawyer
Washington Post Staff Writer
Saturday, March 8, 2003; Page A02
HOUSTON, March 7 -- A fuzzy Air Force photo of the space shuttle Columbia in its final moments is revealing more to investigators than they first realized, including what may be a vortex of superheated air roiling over the left wing and a section of heat-shield panels missing from the leading edge.
The plume trailing behind the shuttle's wing looks like "part of the heated material coming off the aircraft," an official close to the investigating board said today.
The image, basically a silhouette, shows something protruding along the leading edge of the left wing, and some analysts are now inclined to interpret that as showing that "a large number of RCC panels are missing," the official said, referring to the heavy-duty carbon-fiber heat shielding bolted to the wing's leading edge.
With the U-shaped panels gone, the front edge of the wing would be a flat expanse of naked aluminum, as streamlined as a two-by-four and very vulnerable to the intense heat of reentry.
Wind tunnel tests have indicated to the investigators that the leading edge must have lost several panels to produce the kind of heavy drag that the shuttle experienced in its last minutes, the official said. The final dregs of telemetry from the shuttle have shown that the onboard computer was fighting a losing battle to maintain control of the shuttle against increasing drag on the left side.
"If [the image] is real, and I'm beginning to think it is, it's showing a lot of pieces" missing. "Not one, not two . . . at least three," the official said. Most likely there was a zipper effect in which one panel came off, exposing and weakening the next until it ripped off, and then the next and the next.
The investigating board, headed by retired Navy Admiral Harold W. Gehman Jr., is putting together an ever-fuller portrait of Columbia's final moments before it broke up over Texas on Feb. 1, but members continue to stress that they are pondering more than one scenario to explain the accumulating evidence from the wreckage, telemetry, photographs and other sources.
The newest clue may come from a piece of one of Columbia's computers or other electronic device recovered recently in the search for wreckage. Investigators hope to find traces of decipherable data in the device's memory, a spokesman for the board said today.
The investigators have concluded that a breach, or burn-through, somewhere in the shuttle's underbody near or on the left wing, is the likeliest explanation for the evidence found so far. The breach could have been caused by chunks of material that broke from the shuttle's external tank during the Jan. 16 liftoff from Cape Canaveral, although the board is still considering other possibilities.
The recovered wreckage accumulating at a hangar at Kennedy Space Center in Florida has begun to show a pattern of charring and burning that will help investigators work backward to pinpoint what caused the breach.
In the effort to understand why the shuttle began shedding parts high over California, and in hopes of recovering more of them, investigators have sent key segments of the wreckage to Wright-Patterson Air Force Base in Ohio for testing to determine what their radar signature would have looked like on ground radar images of the shuttle, the board said today.
The official said if the impact during launch was the cause of the damage, something could have been loosened but left in place until the shuttle reached orbit. Although the video shows no obvious damage during liftoff, the orbiter was subjected to a heavy vibration and as much as three times Earth gravity on its way to orbit.
When it turned off its main engines, the effect was like putting the brakes on, he noted. An unidentified object was seen on radar separating from the orbiter on the second day of its mission, possibly a result of this sequence. Or, he said, a loosened piece could have been "hanging on by a thread" until it broke free in the stress of reentry.
As the shuttle descended across the Southwest, it was flying normally, and the seven astronauts showed no awareness of anything amiss -- even as ever-larger pieces of the shuttle were apparently peeling off. "There's a lot of stuff coming off this orbiter, and nobody's saying anything," said the board official, most likely because the shedding was obscured by the glowing plasma, superheated gas that builds up around the shuttle as it enters the atmosphere at hypersonic speed.
Investigators are especially interested in finding the sixth piece of debris seen breaking from the orbiter in images taken from the ground, the source said. Radar tracking and ballistics calculations involving "simple Galileo-type" physics indicate it fell around Caliente, Nev., now the scene of an intense search.
Based on its ballistic properties and the way it reflects light, analysts have estimated this piece to "pretty massive, pretty big," the source said, holding his hands about a foot and a half apart.
The location of the breach in the shuttle's skin remains a topic of debate, and the investigators have differing theories. The "area of interest" extends along the underbody just inboard and forward of where the wing flares out from the fuselage, including an area around the left wheel well.
There has been informed speculation in recent days that a "blowtorch" of hot plasma penetrated the orbiter's skin, passed through the wheel-well housing, and then out the wheel-well door and onto the leading edge of the wing.
The surmise is based in part on the pattern of damage seen on recovered wreckage from these key areas, the official said.
© 2003 The Washington Post Company
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