Beyond Columbia


As the pain of the Columbia disaster eases, a group of Embry-Riddle experts in spacecraft and space mission design, space debris, and aircraft accident investigation offered their insights on what could have caused the accident and what investigators hope to find amongst the wreckage.

Columbia Debris By Dale Smith

The inherent dangers of space travel were tragically brought to the forefront of our collective minds February 1 when the space shuttle Columbia disintegrated upon its reentry high over the western United States.

"With a history of safe and successful reentries, we had come to feel that launch was the most dangerous part of the mission, but it's not that way any more," explained Ron Madler, chairman of aerospace engineering at Embry-Riddle's Prescott, Ariz., campus.

After all, the launch is where all the action is. As one shuttle astronaut put it, "It's like being strapped on the front of a freight train going down the track at 100 mph. You feel all the mass and force behind you." But according to the laws of physics, once that mass gets going it takes just as much effort to slow it down.

"The orbiter weights over 100 tons and it's traveling at over eight kilometers per second when it begins its descent back into the atmosphere," Karl Seibold, assistant professor of aerospace engineering in Prescott, added. "What people do not realize is the goal of reentry is to dissipate all of that built-up kinetic energy, and you have to do it in a very fixed amount of time - about 15 minutes."

"Another way to visualize it," he continued," is to think of four or five nuclear reactors running at full power for 15 minutes - that's the kind of energy the thermal tiles and the air surrounding the shuttle have to dissipate in order to brake the shuttle from orbital velocity (about 18,000 mph) to landing speed (about 200 mph). My students and I worked it out in class, and the numbers are pretty intense."

And that very intensity is the reason that the debris field from Columbia's break-up is spread out over 28,000-square miles across five states. The idea of mounting a search to recover all the pieces of the spacecraft's wreckage from an area that large is literally mind numbing.

Every piece tells a story
"There are potentially very valuable clues in seeing every piece of the wreckage that can be found," said Chuck Eastlake, professor of engineering at the Daytona Beach, Fla., campus. "The individual pieces can provide information that you can't get anywhere else. Especially in an aircraft accident, there are really useful clues in actually seeing the physical condition of the individual surfaces as they broke apart."

"In this particular case it's even more valuable to recover the pieces that came off earliest in the disintegration," he continued. "They can be tremendously helpful in figuring what came off first and why they came off."

"There are some great parallels between this accident investigation and that of a regular airplane crash," added Bill Waldock, professor of safety science and associate director of the university's Center for Aerospace Safety Education. He is also director of the Robertson Aviation Safety Center on the Prescott campus, where he teaches investigation techniques to students using reassembled airplane wreckage.

"The investigation team will be doing a detailed reconstruction of the vehicle," Waldock said. "They already have a hangar at the Kennedy Space Center 'gridded-out' and as they recover more pieces each one is placed in the approximate location it would occupy on an intact shuttle." One of the major benefits of this process is that it makes it easier to picture the break-up sequence itself, he said.

Investigators must work backward
"We've never seen an accident like this before," said Greg Feith, an Embry-Riddle alumnus who headed the ValuJet crash investigation for the National Transportation Safety Board and is now an aviation safety consultant. "With other aircraft accidents, whether it's a Cessna 172 or an airliner, we can find a common thread from previous accidents that will help use create a chain of cause-and-effect incidents that led to the crash. We have no commonality with this accident."

"That's why it's so important to look at every piece we can find," Feith continued. "Wreckage, telemetry information, flight controller inputs - the most probable cause will come from the best possible evidence."

Waldock expects Columbia's crash investigators to use "ballistic trajectory analysis," a process that begins where the pieces are found and works backwards, essentially putting them back in flight on the intact aircraft. Since there is no real data to be collected from the spacecraft's computers, this may be the only way to figure out what happened. "The amount of effort they're throwing into this investigation is unparalleled," Waldock said. "I understand that they're using some of MIT's supercomputers to do some of the modeling."

"The investigation team will literally be out there playing Dick Tracy," Feith said. "They're using all they can find to put together the best story they can on why we lost the aircraft and, more important, what we can do to keep it from ever happening again."

Delta II Tank Space debris a probable cause
Seemingly from the very moment the accident happened, space experts have put impact from space debris at the top of the list of what may have caused the catastrophe.

"Space debris are pieces of junk that are floating around in orbit," Eastlake said. "Most are small pieces that have come off of satellites or other space vehicles. I believe the number is estimated at somewhere around 12,000 items in low-Earth orbit.'

"Unfortunately, because a lot of those pieces are very small, there isn't really anything that can be done about it," he added. "Some people have talked about putting a laser-weapon on the shuttle so you can blast anything before it hits the space craft. That's one of a number of science fiction-type solutions. While, it is technically possible, it isn't really practical."

Besides the dramatic cost and weight penalties of "arming" the shuttle against impact from space debris, the fact is you probably wouldn't be able to see the pieces coming at you. "The directionality of the impact is a big consideration," Seibold explained. "In orbit, you kind of expect impacts to come from the sides or top. Pretty much everything up there is traveling in the same direction, unless it's been deflected by another object."

"As space debris goes, the shuttle already travels at the cleanest altitudes," Seibold continued. "Most of the debris is orbiting at altitudes from 400 to 2,000 kilometers, and the shuttle usually orbits below 400 kilometers. That's about all NASA can do about the problem. You really can't avoid it. They just have to do what they can to keep track of it." And hope for the best.

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