February 2, 2003

Experts: Columbia left few clues intact

By JOHN LeBAS

Eagle Staff Writer

Bryan College Station Eagle/Butch Ireland

A piece of the Space Shuttle Columbia rests in the median of State Rouote 155 about seven miles north of Palestine Saturday. Officials said it was one of the largest pieces found in Anderson County.

The space shuttle Columbia could have been doomed by a failure of its heat-protecting tiles, or by poor positioning as it screamed toward a landing on Earth, experts at Texas A&M University said.

Either scenario could have initiated the spacecraft’s catastrophic disintegration Saturday. But scientists at A&M said investigators could have difficulty pinpointing the exact cause because of the widespread field of debris and condition of the wreckage.

“You won’t find out much from fragments on ground,” said Ray Askew, a distinguished research scientist with the Texas Engineering Experiment Station, which is based at A&M.

Because the shuttle fell apart at 200,000 feet — 38 miles above Texas — its raining remnants would have melted or burned from the intense heat of friction, said Askew, a former NASA scientist. The heat could have destroyed physical evidence of what caused Columbia to disintegrate.

That heat — which can reach 3,000 degrees as the shuttle slices through the upper atmosphere — may also be considered as a culprit in Saturday’s tragedy, Askew said.

NASA’s shuttle craft are lined underneath with tiles that take the brunt of re-entry heat. If some of those protective tiles were missing or broken, that could have exposed parts of Columbia to destructive temperatures.

Or, the shuttle may not have come in at the right angle, Askew said. The landing is handled by computer but can be taken over by the pilot if necessary.

If poorly positioned, the craft — which is essentially a glider upon re-entry — could have started to tumble, Askew said. Columbia, hurtling through the sky at 12,500 mph, could not have withstood the forces of such a roll.

“If you’re not in the proper orientation, or you’ve lost tiles, you’ve got a thermal problem,” Askew said, adding that NASA’s investigation could point to other problems the shuttle encountered.

Eagle photo/Butch Ireland

A red cross stands at the site of a piece of the Space Shuttle Columbia debris iin Nacogdoches.

John Junkins, a distinguished professor of aerospace engineering, also said NASA will likely examine whether the shuttle was correctly positioned.

“If the shuttle is not oriented properly, it will disintegrate because only the thermal heat shield has the ability to withstand the re-entry heating,” Junkins said. “It can melt aluminum.”

Throughout the day, TV reporters speculated that the shuttle catastrophe could be linked to its Jan. 16 launch, when a piece of insulating foam broke lose from the external fuel tank and struck a wing. NASA officials, though, said they did not believe the foam caused significant damage to heat tiles or other parts of the shuttle.

Askew said it was difficult to determine from video shot from the ground whether an explosion triggered the disintegration.

Columbia did carry fuel, used for powering steering rockets, that could have ignited or exploded as the craft broke apart. Video appeared to show fire and smoke trails as chunks of wreckage hurtled down in Texas and Louisiana.

Askew said it is unlikely that Columbia struck debris as it returned to Earth, but he did not rule out the possibility. Most manmade space trash orbits the planet 200 miles above its surface, and the U.S. Air Force can track objects as small as 4 inches with ease, he said.

“We’ll certainly know if there was anything sizable in that area ... but it certainly wouldn’t be the first thing I’d be looking for,” he said.

Federal officials also quickly ruled out terrorism, saying that Columbia was out of range of surface-to-air missiles.

Investigators are now left to comb through wreckage scattered over two states and computer data logged from shuttle transmissions to determine what happened.

“They won’t announce a finding for weeks, if not months,” Junkins said.

• John LeBas’ e-mail address is jlebas@theeagle.com.

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