Just two days before Columbia’s mysterious break-up during its fiery descent, a safety engineer warned by e-mail about risks of “catastrophic” failures from extreme heat causing the shuttle’s tyres to burst inside the spacecraft, Nasa has disclosed.
Meanwhile, searchers near Hemphill, Texas, about 140 miles north east of Houston, said they recovered what they believed to be one of Columbia’s tyres.
It sustained a massive split across its tread, but it was impossible from photographs to know whether the tyre was damaged aboard Columbia or when it struck the ground. Nasa officials in Washington said they could not confirm the tyre was the shuttle’s.
Engineer Robert Daugherty, responding to a query from Johnson Space Centre, cautioned Nasa colleagues in remarkably strident language that damage to delicate insulating tiles near Columbia’s landing gear door could cause one or more tyres 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 gealowered 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 break-up but 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. Nasa disclosed the contents of his e-mail yesterday.
The e-mail from Daugherty, an engineer at Nasa’s Langley research facility in Hampton, Virginia, was prompted by a telephone call on January 27 from experts at the Johnson Space Centre in Houston, who asked what might happen if Columbia’s tyres were not inflated when it attempted to land.
The inquiry from Johnson has attracted interest because it came four days after engineers at Boeing, a contractor, assured Nasa that Columbia could return safely despite damage to left wing tiles that might have occurred on lift-off.
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 threats to the shuttle’s tyres were not passed along to Nasa flight directors.
Meanwhile, search crews combing the woods of east Texas for remnants of space shuttle Columbia found “significant amounts” of human remains and an astronaut’s patch.
:: Two Dutch Air Force pilots at Fort Hood for a training flight on an Apache helicopter captured video of the space shuttle Columbia as it disintegrated over North Texas.
The video was turned over to Nasa, which is interested in the co-ordinates captured by the military camera.
“This camera is more powerful than others” that have shuttle footage, Maj Matt Garner, a public affairs officer at Fort Hood, said. “It has the exact time, down to the second, along with the direction the camera is looking and exact location of the (Army) aircraft.”
The helicopter was about 100 feet from the ground in a landing manoeuvre when the pilots captured the footage on February 1.
“They knew the shuttle was coming and had been watching to see it,” Garner said. But the men could tell something was wrong.
“One pilot said his thoughts were immediately of the people that were in the shuttle,” Garner said.