Debris search still fails to find crucial parts of shuttle

NACOGDOCHES, Texas -- Despite gathering more than 12,000 pieces of debris from the shuttle Columbia, a NASA official said Wednesday none of the pieces provides critical answers for why the shuttle broke up.

"We do not have any red-tag items," said Ron Dittemore, shuttle program manager, referring to items engineers have identified as crucial to the investigation into the cause.

He said those items would include parts of the left wing, data recorders and certain pieces of insulation and tiles.

The widening search now extends from Louisiana to California.

In Texas alone, officials have identified 38 counties with debris, while pieces have turned up in two dozen Louisiana parishes. And NASA investigators are checking California and Arizona for debris as well.

"The scale makes it unprecedented," said Dave Bary, a spokesman for the Environmental Protection Agency, which is overseeing the collection of debris. "The debris field is so large -- covering so many counties -- I can't think of anything historically that would compare to this," he said.

That could delay meaningful analysis of those parts that have been collected -- and what role they might have played in the disaster, NASA spokesman Rob Navias noted.

"We have to put the puzzle together before we see what the mosaic looks like," Navias said.

Nickel-sized pieces

The shuttle was composed of about 2 million parts, many of which shattered into pieces as small as a nickel.

Bill Waldock of Embry-Riddle Aeronautical University in Arizona said any of the craft's 20,000 insulating tiles or metal components from the left wing would be significant.

At least two possible wing sections have been discovered in east Texas, although authorities did not know from which side of the shuttle they came.

A patch of foam insulation that broke off from the shuttle's external fuel tank during launch and struck tiles on the underside of the left wing had been the focus of the probe into the possible causes of Columbia's destruction. After days of analysis, NASA backed away Wednesday from the theory that the foam might have been the root cause of the accident.

Instead, Dittemore said investigators are focusing more closely on the frantic effort of Columbia's automatic control system to hold the speed of the spacecraft stable despite increasing wind resistance, or drag, on the left wing.

The insulating tiles protect the underbelly and the wings of the shuttle from searing heat. Each is stenciled with a code to tell engineers where it was located on the craft. Tiles that peeled off the left wing had been considered crucial to the probe.

Waldock said some pieces -- such as the nose cone, found Monday in east Texas -- could help investigators rule out other potential causes of the disaster. "It didn't look like the nose cone had much thermal damage at all; it's not even really scorched," he said. "It means that area was not exposed to the high temperatures."

"The sequence of events and of the debris on the ground is going to be very important to unraveling this mystery," noted William Ailor, director of the Center for Orbital and Re-entry Debris Studies at The Aerospace Corp. in El Segundo, Calif.

Bad of bad weather Wednesday, the Forest Service opted not to ferry the nose cone out of the area by helicopter. Instead, a road was hewn through the forest and the cone was loaded onto a truck.

Another expert said the pattern of where pieces fell would offer important clues. The heat of re-entry would have peeled back the shuttle, layer by layer, heating and breaking off pieces in succession as it streaked eastward through the atmosphere, noted William Ailor, director of the Center for Orbital and Re-entry Debris Studies at The Aerospace Corp. in El Segundo, Calif.

"It's basically like heating an onion," he said.

"The sequence of events and of the debris on the ground is going to be very important to unraveling this mystery," noted William Ailor, director of the Center for Orbital and Re-entry Debris Studies at The Aerospace Corp. in El Segundo, Calif.

As Columbia shed debris, dense and streamlined objects would have traveled farther eastward. That explains why the shuttle's heavy, heat-resistant nose cone traveled as far east as it did, Ailor said.

Lightweight, less aerodynamic pieces of debris, including the thermal tiles that coated the underbody of Columbia, would settle more quickly to the ground after breaking off.

Recovery teams are using global-positioning system satellites to determine the location of each piece of debris so the field can be mapped. NASA hopes to use that information to develop computer models to simulate the disaster. The models would track each piece of debris back in time to the moment it was shed from the orbiter.

"The two most critical things are determining where the pieces are and identifying the precise location where those pieces came from on the shuttle, no matter how small or large," said James Kroll, who is heading the mapping project at Stephen F. Austin State University in Nacogdoches.

"Then we can make them jump back up into the air and go back to that part of the spacecraft."

Retired Adm. Harold Gehman, chairman of the independent panel investigating the disaster, said such computer simulations would be pivotal in determining how the shuttle failed.

Four days after Columbia shattered on its journey home to Florida, more than 1,200 people were picking up the pieces in Texas and Louisiana, traipsing through forests and cow pastures in rain and sleet to hunt down smaller items that can be retrieved by hand.

Federal prosecutors, meanwhile, were cracking down on accused looters. Two East Texas residents were charged with theft of government property for allegedly taking a circuit board and a piece of thermal insulating fabric. They could face up to 10 years in prison. Amnesty was offered through Friday evening for anyone else who handed over shuttle parts.