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Recordings may offer clues about Columbia NASA investigating sound wave patterns as shuttle broke apart By Andrew Bridges, Associated Press, 2/17/2002
The instruments also captured an explosion high over Texas that one scientist said could have been Columbia's cabin rupturing. As parts of Columbia began to break off while the shuttle streaked across the West, the flight behavior of the normally streamlined spacecraft would have changed. Those changes would have generated patterns of sound waves distinctly different from those of previous shuttle flights. The patterns, recorded on the ground by instruments in Texas and Nevada, as well as elsewhere in the West, are being examined as part of the Columbia disaster investigation. Any abnormal patterns can help investigators establish the timing of events as the shuttle entered the earth's atmosphere Feb. 1, said Keith Koper, a geophysicist at Saint Louis University in Missouri. Investigators know from sensor data sent from the shuttle in its final minutes - supported by eyewitness reports, photographs, and video footage - that Columbia's cascade of problems began while the spacecraft was over the Pacific Ocean.
The sensors indicated increasing heat and increased drag on the shuttle's left wing, suggesting it was damaged, perhaps from the impact of a chunk of hard foam that broke off the external fuel tank and hit the wing after liftoff Jan. 16. Investigators have said they suspect that this data mean Columbia already was dropping debris over the West, several minutes and hundreds of miles before it broke apart high over Texas. All seven crew members were killed. Sound-sensitive instruments near Big Bend National Park in southwest Texas recorded sound waves from Columbia as it was over western Texas - indicating an explosion equivalent to that produced by a few pounds of TNT, said Eugene Herrin, a geophysicist at Southern Methodist University. ''Our guess is that it could have been caused by a rapid decompression, which is what would have happened if you ruptured the crew compartment,'' Herrin said. He said an initial analysis of data collected in Columbia's wake by other microbarometers outside Mina, Nev., showed ''unusual'' patterns when compared with data from other shuttle flights passing overhead. The instruments record minute pressure changes caused by infrasound, or sound waves below about four cycles per second that are inaudible to humans. ''There was something about this one; I am not going to speculate,'' Herrin said. ''What we see are oscillations in the shock wave that we don't normally see. Whether that's diagnostic or not, that's a NASA call.'' Space agency spokesman William Jeffs said yesterday that NASA would consider the information in its investigation. Search crews have not found any confirmed shuttle debris more than 20 miles west of Fort Worth. A search in a canyon east of Albuquerque on Saturday turned up nothing from the shuttle, officials there said.
This story ran on page A2 of the Boston Globe on 2/17/2002.
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© Copyright 2003 New York Times Company |
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OUSTON - Recordings made by instruments sensitive to sound below the threshold of human hearing may help investigators build a timeline of any uncharacteristic movements made by the space shuttle Columbia minutes before it broke apart, scientists say.
