NASA investigators have moved away from a theory that the Columbia tragedy stemmed from falling foam insulation and now says a piece of space junk or a small meteor may have hit the shuttle, according to a report.

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An expert said even if a scrap of debris grazes the shuttle, it could have damaged the thermal tiles and started a chain reaction.

"Did we take some hit? That's a possibility. Something was breached," Milt Heflin, the space agency's flight director told a Los Angeles newspaper.

Heflin said there is no evidence that Columbia was struck by a piece of space junk or a micrometeor.

There are believed to be more than a million objects within 1,200 miles of the Earth's surface.

Columbia To Be Reassembled In Brevard

Pieces of shuttle Columbia will be reassembled at Kennedy Space Center, according to NASA's shuttle program manager Ron Dittemore.

The thousands of pieces of shuttle debris are currently being collected at Barksdale Air Force Base near Shreveport, La.

However, officials said the orbiter will eventually be moved to Kennedy Space Center.

"Eventually our plan is to move the debris to the Kennedy Space Center," he said.

The National Transportation and Safety Board does something similar in reconstructing airliners after accidents.

Shuttle engineers and mechanics who know the intricacies of the ship where it is assembled at KSC will likely concentrate their efforts on reassembling the craft.

Dittemore did not elaborate when the operation would take place.

Shuttle Challenger was reconstructed at the Logistics Facility after the Jan. 28, 1986, disaster. It remains buried in a silo at Cape Canaveral Air Force Station.

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Investigation Focus Turns To Shuttle Computer Data

NASA is redoubling efforts to get missing computer data from shuttle Columbia, now that engineers are backing away from a prime theory on what caused the disaster.

Engineers said a piece of insulation foam from the shuttle's external fuel tank was not big enough to severely damage the protective thermal tiles.

Dittemore is pinning hope on recovering 32 seconds of sensor data sent after voice contact was lost. Experts are hoping the information -- if it can be decoded -- will shed more light on problems that developed on the Columbia's left wing before the spaceplane broke apart.

Meanwhile, NASA said none of the more than 12,000 pieces of debris recovered so far provides a crucial answer on why the shuttle disintegrated.

NASA investigators are combing through thousands of pieces of debris for clues on what caused the space shuttle Columbia to break apart.

But not all of what's being turned in is from the shuttle. A lot of it is junk. Items checked by investigators range from a truck mudflap and an alternator from a Chevy, to an egg yolk and a piece of burnt toast.

Americans, eager to help, are reporting debris from California to Georgia and as far north as Kentucky. A woman in northwestern Kentucky found a piece of metal with embossed numbers on her patio; state police have sent a photo of it to NASA.

A spokesman for the space agency said it's easy to speculate or be confused. But experts say they'd rather comb through a thousand pieces of junk than miss a piece of Columbia that could yield a clue.