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NASA engineer had warned of tire risks
By Ted Bridis, Associated Press, 2/13/2003
Separately, searchers near Hemphill, Texas, about 140 miles northeast of Houston, recovered what they believed to be one of Columbia's tires. It sustained a massive split across its tread, but it was impossible from photographs to know whether the tire was damaged aboard Columbia or when it struck the ground. NASA officials in Washington said they could not confirm the tire was the shuttle's. Engineer Robert H. Daugherty, responding to a query from Johnson Space Center, cautioned NASA colleagues in remarkably strident language that damage to delicate insulating tiles near Columbia's landing gear door could cause one or more tires inside to burst, perhaps ending with catastrophic failures that would place the seven astronauts ''in a world of hurt.'' Such an explosion inside Columbia's belly, Daugherty predicted, could blow out the gear door and expose the shuttle's unprotected innards to searing temperatures as it raced through Earth's atmosphere.
Even if astronauts survived the heat, the blast could damage critical systems inside the wheel compartment, prevent the landing gear on one side from lowering, necessitate a risky belly landing, or force the crew to bail out, Daugherty wrote. Bailing out would be ''not a good day,'' he wrote. But attempting to fly the shuttle with only one side's landing gear lowered would be worse: ''You're finished.'' Flight Director Leroy Cain said yesterday that investigators were confident the gear door did not fall off in flight because such a failure would have been indicated on sensor readings. Other NASA officials have cited mysterious sensor readings in the wheel well moments before Columbia's breakup but have said they were confident the tire didn't burst inside the shuttle. Daugherty acknowledged in his e-mail that these were ''absolute worst-case scenarios'' but defended citing them: ''You should seriously consider the possibility of the gear not deploying at all if there is a substantial breach of the wheel well.'' He referred questions about his concerns to a NASA spokesman. Agency officials indicated they did not want reporters to speak with Daugherty because accident investigators had not yet questioned him. The e-mail from Daugherty, an engineer at NASA's Langley research facility in Hampton, Va., was prompted by a telephone call Jan. 27 from specialists at the Johnson Space Center in Houston who asked what might happen if Columbia's tires were not inflated when it attempted to land. The inquiry from Johnson has attracted interest because it came four days after engineers at The Boeing Co., a contractor, assured NASA that Columbia could return safely despite possible damage to left wing tiles. Senior NASA officials said Daugherty's concerns were part of a ''what-if'' analysis by a small group of engineers who already had been assured that Columbia would land safely. They acknowledged that concerns about the shuttle's tires were not passed along to NASA flight directors. Milt Heflin, chief of the flight director's office, said Daugherty and others involved in the tire questions ''were happy with the analysis and the work that was done'' by Boeing. An e-mail back to Daugherty the next day from a Johnson Space Center engineer, David F. Lechner of the United Space Alliance LLC, another NASA contractor, thanked Daugherty for his ''candid remarks.'' He said they ''generated extremely valuable discussion in our group.'' Another Langley employee, Mark J. Shuart, responded by e-mail later that day, ''Looks like they believe all this has been addressed.'' His message was time-stamped about 20 hours before the shuttle disintegrated. Senior NASA officials have repeatedly expressed confidence in Boeing's conclusions, which predicted ''safe return indicated'' even if foam insulation that fell from Columbia's external fuel tank had caused ''significant tile damage.'' That study assumed foam debris struck part of Columbia's left wing, including its toughened leading edge and the thermal tiles covering the landing gear. Testifying at a joint congressional hearing yesterday, NASA Administrator Sean O'Keefe told lawmakers that during Columbia's 16-day mission, ''there were no abnormalities that would suggest a problem.'' Among the earliest warning signs aboard Columbia in the minutes before its demise was an unusual heat buildup of about 30 degrees inside the left wheel well. Investigators have said they are confident the tire inside didn't deflate, but they have been unable to explain the readings.
This story ran on page A8 of the Boston Globe on 2/13/2003.
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© Copyright 2003 New York Times Company |
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ASHINGTON - Just two days before Columbia's mysterious breakup during its fiery descent, a safety engineer warned by e-mail about risks of ''catastrophic'' failures from extreme heat causing the shuttle's tires to burst inside the spacecraft, NASA disclosed yesterday.
