Rejected theories in Columbia shuttle probe back on the table

SPACE CENTER, Houston -- In the days after Columbia's destruction, NASA officials made their case: The foam couldn't have caused that kind of damage. It wasn't ice or metal that flew off the fuel tank. The left wing was not breached.

All that -- and more -- is back on the table and under the microscope, now that an investigation board is calling the shots.

In the 2 1/2 weeks since Columbia shattered 38 miles above Texas, both NASA managers and board members have cautioned that the investigation is in continual flux, with new information turning up all the time. On Wednesday, NASA said the shuttle's nose landing gear was found in the east Texas woods.

But it is the board that has emphasized that everything is under consideration, no matter how seemingly irrelevant or obscure or unimaginable.

The fact that the accident investigation board has put NASA's discarded theories back on the table is "a combination of being thorough and being independent," said NASA's Steve Nesbitt, who is temporarily serving as the board spokesman.

The 10-member board -- soon to gain a new member or two -- is being scrutinized for signs of independence because it was chosen by NASA.

"The board wants to make sure every base is covered," Nesbitt said Wednesday. "They're not going to take NASA's word that everything is OK in a particular area."

For example:

After first considering damage to Columbia's heat-protecting tiles by the foam insulation falling off the fuel tank during launch, shuttle program manager Ron Dittemore soon ruled it out: "It just does not make sense to us that a piece of debris would be the root cause for the loss of Columbia and its crew," said Dittemore. "There's got to be another reason." He later softened that. But now with the board members in control, the foam appears to be a central focus.

Space agency officials at first said it was doubtful any large chunk of ice formed on the fuel tank and broke off. Dittemore also said the foam insulation was "essentially waterproof; it does not absorb moisture," and thus could not contain ice. He also dismissed any other substance besides the foam. "We do not believe it was any metal ... and so I don't believe there's any chance that it was hardware." Now the board wonders if the debris was ice, foam with ice, or the heavy insulating layer beneath the foam.

NASA quickly discounted the age of its oldest space shuttle, which had been flying for 22 years. On Tuesday, the board promised to look into whether the age of the regularly refurbished spacecraft might have played a role.

Officials more or less dismissed the notion that space debris could have brought down Columbia. But it is on the board's list of possible causes.

NASA said a breach in Columbia's left wing was unlikely given the surge in temperatures that was detected. "I have no breach," Dittemore said. But the board concluded that the wing had to have been penetrated by the superheated gases surrounding the descending spaceship, and the breach had to have been bigger than a pinhole. How much bigger is still unclear.

Even sabotage, a notion that is anathema to NASA, is not being ruled out for the flight that carried Israel's first astronaut, Ilan Ramon.

"I don't like to use the word sabotage. But among the broad investigation that we're conducting, purposeful or willful damage is one of the things that we're looking at," the board's chairman, retired Navy Adm. Harold Gehman Jr., said Tuesday.

The fact that an Israeli war hero was among the seven astronauts killed is not driving that part of the investigation, Gehman insisted. "We are not doing it any more strongly because of the Israeli astronaut," he said.

The board said it would check the training and certification of the Columbia astronauts and flight controllers and also see whether budget pressures or poor management decisions contributed to the accident.

As for the hole in the wing, it could have developed inside or outside Columbia, the board said. Gehman said it's possible the explosive charges inside the left landing gear compartment may have gone off. Again, NASA dismissed that idea early on.

"Obviously, the NASA people in the immediate wake of the disaster have a tendency toward saying, 'We did everything right,' " said Steven Schneider, professor of aeronautics and astronautics at Purdue University. "It's human nature, especially if you knew the people who died. Then there's always, everybody has a tendency according to their interest to interpret the data in a way they like."

Schneider fears that may have happened with the in-house engineering analysis into the potential damage from the impact of tank debris during liftoff.

Within a week, NASA and its contractor engineers had concluded that the damage to Columbia's thermal protective layer, if any, was minimal and posed no safety threat. Shuttle managers signed off on the findings five days before the shuttle ended its science mission and headed home.

That entire evaluation is now being redone, in excruciating detail.

NASA has maintained from the start that even if it had known the insulating tiles or panels on the left wing were severely damaged, there was nothing the astronauts could have done to save themselves.

That, too, is back on the table.