NASA: Columbia had `steady stream' of pieces falling off, as wires in left wing burned
Monday, March 17th 2003, 12:00 am
News On 6
HOUSTON (AP) _ Columbia lost â€œa steady streamâ€ of pieces from California all the way to its final breakup over Texas, as wires in its left wing burned and shorted out, shuttle officials told the accident investigation board Monday.
â€œWe continue to be shocked that we had debris coming off the orbiter as we crossed the California coastline,â€ said NASA flight director Paul Hill. He is leading debris recovery efforts in the West, which so far have yielded no wreckage.
Later, to illustrate his point, Hill showed a video that was a composite of 15 to 20 amateur videos sent in by citizens.
Hill expressed amazement that during much of the time debris was falling and sensors were going haywire _ probably from hot atmospheric gases that had entered a hole in the left wing _ â€œthe vehicle flew perfectly, no indication of what was going on in flight control.â€
Aside from unusual temperature and pressure readings and sensor dropouts, â€œthe vehicle flew like a champ right up until the breakup, so that did surprise us,â€ he said, testifying in the second hearing of experts before the investigation board. Another hearing is set for Tuesday morning.
He and another shuttle official, Doug White of the NASA contractor United Space Alliance, said the sensors probably started blinking out one by one as the wires burned inside the left wing and, in some cases, simply shorted during Columbia's doomed re-entry on Feb. 1.
The investigation board suspects the left wing was breached possibly by launch debris 16 days earlier. At least three pieces of insulating foam or other material on the external fuel tank snapped off and hit the wing.
In the videotape Hill showed, the shuttle is seen as a bright, white object against the dark sky; 15 times, a piece big enough to be seen came off. Twice, a flash accompanied the shedding object, perhaps the result of combustion _ in other words, the pieces may have been burning when they came off.
Hill told the seven board members present that without the videos, â€œWe wouldn't know any of this. These people are definitely our heroes.â€
An expert in spacecraft re-entry, William Ailor of the Aerospace Corp., said 10 percent to 40 percent of the pieces that typically fall from a returning spacecraft usually survive atmospheric re-entry. Most of that falls in the ocean and is never recovered, however, he noted.
He advised the board to focus the debris search on the early wreckage and on parts of the shuttle of particular interest, like the left wing.
He said it is critical to the investigation to find some of shuttle pieces that fell out West. So far, that hasn't happened.
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