2003年2月3日
UW experts react to disaster
by Kathleen Belew, The Daily
FEB/03/2003
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The space shuttle Columbia disintegrated over east Texas Saturday morning, killing its seven-member crew and leaving a trail of debris across a string of rural communities. One of the seven, payload specialist Michael Anderson was a UW alumnus.
Anderson completed his undergraduate work in 1981 with a degree in physics and astronomy. He was 43, and leaves behind a wife and two daughters.
Also on board the shuttle were David Brown, Kalpana Chawla, Laurel Clark, Rick Husband, William McCool and Ilan Ramon.
UW Interim President Lee Huntsman will meet with deans today to discuss a memorial for Anderson and the other crewmembers. Flags will fly at half-mast across the United States until Wednesday, as determined by President Bush. The UW flag may remain lowered beyond that time.
Columbia lost communication with the NASA at 9 a.m. EST; it was scheduled to land at Florida’s Kennedy Space Center at 9:16 a.m. When communications broke, the Columbia was traveling at 12,500 mph — 18 times the speed of sound — and at an altitude of about 203,000 feet.
Although NASA has not yet determined the cause of the tragedy, early analyses have pointed to faulty ceramic tiling on the left wing of the shuttle. A piece of insulating foam came loose from one of the shuttle’s external fuel tanks during launch, hitting its left side. Temperature sensors in the same location reported it was heating up four times faster than the right side of the shuttle just before it broke up.
Jim Hermanson, UW aeronautics and astronomic professor specializing in combustion and propulsion at high speed, said even minor damage to the ceramic tiles could be devastating. Tiles along the nose, tail and wings — the main protection against the heat of atmospheric re-entry, which is most intense at those locations — are the most critical.
“If one of those was damaged, it would have very serious consequences,” Hermanson said. “There’s so much critical technology, and so many things that can go wrong. This is not the same as commercial aviation, where there are millions of flying miles.”
Rolf Rysdyk, an assistant professor in aeronautics and astronautics, said that re-entry is an incredibly delicate phase of a space-shuttle flight. He compared it to driving 200 miles per hour on an interstate — safe until the car hits a rock.
“That [shuttle] is made to go really fast, but only if nothing goes wrong,” Rysdyk said. “[Re-entry] is like skipping a stone, allowing it to very slowly get into the Earth’s atmosphere.”
Rysdyk said accounts from east Texas of a close sonic boom indicated real trouble.
“That tells me that they ended up in a very steep descent, much steeper than [it] should have been,” he said, adding that a commercial jet descends from its cruising height of 35,000 feet at about 1,000 feet per minute. “They must have been losing thousands of feet per minute.”
Hermanson said the problem could have been getting worse for several minutes, unknown to the crew until a “drastic loss of control.” At that point, there would have been little time left for action.
“When they discovered they had a real problem, it probably went pretty quickly,” he said.
The telemetry — data from the sensors on the Columbia, including voice transmissions — will be closely scrutinized for more information, Hermanson said.
“In a case like this, there’s no wreckage,” he said.
Hermanson remembers the Challenger disaster 17 years ago that spurred discussion about the safety of the space program. Someone told him that every time a mission begins, the odds of a catastrophic accident are about one in 400. Add that to an aging space-shuttle fleet (the Columbia was the oldest shuttle of its kind) and a very low number of test flights, and the risk becomes extremely high.
“The problem is, there have been relatively few shuttle flights compared to other air vehicles. It’s a risky situation ... this is a risky business, just not an inherently safe thing to do.”
Adam Bruckner, professor and chair of aeronautics and astronautics, said a generally good track record within the shuttle program makes disasters more shocking.
“My heart sank to my feet,” Bruckner said. “Everything has gone so well, people take it for granted.”
News of the Columbia tragedy shocked Hermanson.
“When I first got the news, I felt like the whole world was falling apart,” Hermanson said. “Like a dream. This isn’t happening.”
For Rysdyk, the Columbia tragedy bring doubts about the field as a whole, as well as its six major specializations.
“The space shuttle combines all of these disciplines. If something goes wrong, it could be in any one,” Rysdyk said. “If something goes wrong, how are you going to find it?”
He also expressed surprise that the shuttle crew didn’t use the robot arm to examine the extent of the foam damage, as is usually done. Had they known of a flaw in the ceramic tiles, the crew may have been able to prevent the disaster, according to Rysdyk.
“There was a possibility they could do something — a slight turn as they came in.”
Huntsman’s reaction reflected that of many outside the field.
“I was kind of brokenhearted about the whole crash. It just sort of gnaws at you ... we’re all going through a shock type of reaction.”
“I’ll never forget that moment. There’s nothing like that particular moment in time when you’re in space and finally do what you’ve been dreaming about since you were a kid.”
~ Michael Anderson, OCT. 1998
posted by Biochemie on 4:17 下午
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