The teams NASA appointed to investigate the space shuttle Columbia explosion face a daunting task, one that could take months or even years to turn up answers.

Harold W. Gehman Jr., the retired Navy admiral who helped lead the Pentagon's inquiry into the USS Cole bombing, will head a special government commission, NASA's chief said Sunday.

Gehman's mission will be to sift through all the facts to determine what went wrong on the shuttle, space agency administrator Sean O'Keefe said.

The commission will not emphasize "any pet theory or other approach" but will look into every aspect of the doomed flight that broke up over Texas on Saturday, O'Keefe said on Fox News Sunday.

O'Keefe described the commission as "an independent objective board" and said Gehman would be arriving in Shreveport, La., with a team on Sunday afternoon.

"We're going to find out what led to this, retrace all the events ... and leave absolutely no stone unturned in that process," O'Keefe said.

While much attention focused on reported problems with the spacecraft's left wing, officials cautioned against looking too soon for any "smoking gun" of evidence.

"My promise to the crew and to the crew families is that the investigation we have just launched will find the cause, we'll fix it and then we'll move on," said Capt. Bill Readdy, NASA's associate administrator for space flight.

Just hours after NASA lost track of Columbia and confirmed the shuttle had exploded after re-entry into the Earth's atmosphere, it formed two review boards to investigate what went wrong.

In addition to the external investigation committee, an internal "mishap investigation team"  was assembled at 9:30 a.m. EST -- just minutes after the shuttle missed its 9:16 a.m. EST scheduled landing at Kennedy Space Center in Cape Canaveral, Fla.

Both committees will review all the computer data NASA collected as Columbia began its descent for landing and then broke up at an altitude of 207,135 feet and a speed of 18.3 Mach (18.3 times the speed of sound) over Texas.

"At this point, I have to say it's too early to speculate about the exact cause," said Readdy.

There were initial security concerns for this shuttle expedition because it carried the first Israeli ever to travel in space, Ilan Ramon. But NASA and other officials have said it's highly unlikely this was a terrorist attack, considering the extreme speed and altitude of Columbia when it exploded.

NASA also insists the Columbia aircraft's age -- it was the oldest shuttle in the fleet, and one that had undergone extensive structural overhauls -- was probably not a factor in the accident.

Investigation teams are expected to study whether an incident during the Jan. 16 takeoff contributed to Saturday's disaster.

During liftoff that day, a piece of foam from an orbiter tank broke off and hit the shuttle's left wing, incurring what NASA originally determined was minor damage to the outer insulation tiles. Those tiles protect the spacecraft from the extreme heat the spacecraft endures when leaving and entering orbit.

"It was judged that that event did not represent a safety concern," said Space Shuttle Program Manager Ron Dittemore. But in hindsight, it seems the debris could have had a greater impact than scientists thought.

That's because many of the first signs of a problem with Columbia involved the left side of the shuttle, in the wing area. The first came at 8:53 a.m. EST, when temperature readings of the left hydraulic system disappeared from NASA's tracking system. A few minutes later, there was an increase in left-tire temperatures. Then sensors for the left wing and for tire pressure on the left landing gear stopped working.

"We can't discount that there might be a connection," Dittemore said. "But we can't rush to judgment on it because there are a lot of things in this business that look like the smoking gun but turn out not even to be close."

NASA was already in the process Saturday of impounding hardware to preserve all data received up until the point of communication loss, Dittemore said. Investigation teams will be "poring over that data 24 hours a day for the foreseeable future."

The information they will analyze includes transmissions from the crew, records from the shuttle's sensors and data from military, government and commercial satellites.

Military satellites with infrared detectors saw several flashes as Columbia disintegrated, according to one defense official who spoke anonymously. It was unclear whether those "spikes" of heat indicated an explosion, the burning of debris re-entering the atmosphere or something else.

The teams will also be carefully examining all the shuttle debris collected. Debris collection alone will take quite some time, as the debris field is unusually large -- stretching from Ft. Worth, Texas, through Arkansas and into Louisiana.

NASA and the accident teams will be forming a system for collecting the debris and setting up a central location to store it for analysis.

Currently, there have been 500 or more reports of debris. Law enforcement officials are coming to each scene and taping off the area until a NASA investigator can come and identify it. NASA has set up a hotline for reporting debris or any other information about the accident: 1-800-525-5555, or 1-281-483-3388.

Officials said they were also asking the public to submit to NASA any photographs or videotape they might have taken of the broken shuttle streaking through the sky.

This disaster is unusual because it marks the first time an accident happened during descent in the 42 years of U.S. human space flight.

The shuttle essentially acts as a glider during the hour-long descent process from orbit to the runway. The 20,000 thermal tiles covering the vehicle protect it against temperatures as high as 3,000 degrees.

The Associated Press contributed to this report.