The space agency also will conduct its own investigation into the disaster, O'Keefe said at a news conference in Cape Canaveral, Fla. House Science Committee Chairman Sherwood Boehlert, R-N.Y., said his panel would investigate, as well.

"We're going to get together and fix this problem. We're going to launch shuttles again,'' NASA shuttle project manager Ron Dittemore said at a Houston news conference.

He added there will "certainly be a hold on future flights until we get ourselves established and find the root cause of the disaster.''

NASA established a command post at Barksdale Air Force Base in Louisiana. The National Transportation Safety Board was sending experts in vehicle structures and systems to that base.

The independent panel was assembled Saturday morning and began working right away, said Boehlert, whose House committee oversees NASA. He said he was confident the expert panel would find the cause of the disaster.

The investigations will review all the information that NASA collected as the Columbia began its descent for landing, then started breaking up more than 200,000 feet over Texas.

That information would include transmissions from the crew, as well as records from the shuttle's sensors, analysis of the debris and data from military, government and commercial satellites.

"We will be poring over that data 24 hours a day for the foreseeable future,'' Dittemore said.

Military satellites with infrared detectors saw several flashes as Columbia broke apart, according to a defense official who spoke only on condition of anonymity. It was unclear whether those ``spikes'' of heat indicated an explosion, the burning of pieces of debris re-entering the atmosphere or something else.

O'Keefe and other senior administration officials said there was no indication that any kind of attack from the ground caused the disaster.

FBI spokeswoman Angela Bell also said there was no indication of terrorism and that the FBI would have a minor role in the investigation, mainly helping collect evidence.

Dittemore and chief flight director Milt Heflin told reporters that heat sensors under the trailing edge of Columbia's left wing began failing minutes before NASA lost contact with the shuttle. Dittemore acknowledged that a piece of insulating foam had hit the shuttle's left wing during takeoff Jan. 16, but said it was far too early to tell whether that incident was related to the disaster.

The independent investigation -- similar to one after the 1986 explosion of the shuttle Challenger -- is meant to assure the public and Congress that the cause of the disaster will be found and fixed.

"NASA, the administration and Congress have faced tough choices in regard to funding,'' said Sen. Mike DeWine, R-Ohio, who is on the Senate Appropriations Committee ``There has never been enough money to do all the things we want to do in space. But that was true before this disaster and will be true after this disaster.''

In the 1986 Challenger crash, President Reagan appointed a 13-member commission, headed by former Secretary of State William P. Rogers, to investigate the accident.

After a series of hearings, the commission reported four months later that an O-ring seal leaked in the right booster rocket. That allowed hot gases to burn through the bracket securing the booster to the shuttle, rupturing the shuttle tank.

The shuttle fleet, then consisting of three spacecraft, was grounded for nearly three years while changes were instituted and repairs made.

The Federal Emergency Management Agency took the lead in responding to the Columbia disaster. The military's Northern Command, which handles operations inside the United States, was coordinating the Defense Department's response.

Two F-16 fighters from an Air Force Reserve unit in Fort Worth, Texas, joined in the effort to search for pieces of the shuttle, said Maj. Clay Church, the unit's spokesman.

The Army's 1st Cavalry Division also sent a search and rescue task force from Fort Hood, Texas, to help search for debris.

The task force included helicopters and military police to search for and to guard pieces of wreckage for collection by NASA, Fort Hood spokesman Cecil Green said.

The teams were relying on UH-60 Black Hawk helicopters during the day and OH-58D Kiowa Warrior helicopters at night, Green said.

Homeland Security Secretary Tom Ridge called officials in Arizona and New Mexico to warn them about possible debris, although those states were out of the likely debris field. Oklahoma, Texas and Louisiana were more likely to see shuttle debris.