Sen. Sam Brownback Crossing over California minutes before it broke apart, the space shuttle Columbia heated abnormally on its left side at about the time that an astronomer observed a large, bright object dropping from the spacecraft.
The rising temperatures, together with evidence of increasing wind resistance on Columbia's left side, suggest that heat shield tiles on the shuttle's left side were damaged, NASA officials said at a news conference yesterday.
The unusual cascade of problems began near where a piece of fuel tank insulation struck the spacecraft Jan. 16 during launch.
Shuttle program manager Ron Dittemore cautioned against jumping to conclusions about the cause of the shuttle's destruction Saturday morning. "We've got some more detective work," he said. "We haven't ruled out anything at this point."
As NASA engineers began poring over telemetry and other data from the shuttle's final moments, Dittemore spoke with the California astronomer who watched from the ground Saturday as blobs of light appeared to separate from the shuttle as it streaked across the sky.
"I just imagined they were [heat shield] tiles falling off," said Anthony J. Beasley, a radio astronomer at the California Institute of Technology. But 30 seconds before the shuttle disappeared over the eastern horizon, "there was a single very bright thing falling. ... I said, `Well, that's a very big tile.'"
NASA officials said yesterday that remains of all seven astronauts had been recovered from the debris field that spread along a 500-mile swath across East Texas and northwestern Louisiana.
Investigators hope that the debris, coupled with information beamed from the shuttle in the final seconds before its destruction, will provide important clues. The information will be examined both by an internal NASA "Mishap Investigation Team" and a panel named by NASA administrator Sean O'Keefe, who asserted that it would operate independently.
Yesterday, he named a retired Navy admiral, Harold W. Gehman Jr., who led an inquiry into the terrorist attack in Yemen on the destroyer USS Cole to head the new Columbia accident investigation board. Critics immediately questioned whether a board named by NASA could be truly independent.
More inquiries are being mounted by a growing list of congressional committees, including the House Science Committee, and the Senate Commerce, Science and Transportation committees.
"The key issue for us in Congress is why did it happen, how did it happen, how do we fix it and then how do we project on forward with manned space flight," said Sen. Sam Brownback, a Kansas Republican. "We need to continue that for the vision of the country and the vision of the world."
Nearer the disaster scene, federal investigators from NASA, the Federal Emergency Management Agency, the National Transportation Safety Board, the Department of Defense and other agencies were gathering at Barksdale Air Force Base, near Shreveport, La., which will be the site of initial stages of the inquiry.
Hundreds of pieces of debris have been located, and investigators have begun to truck them to Barksdale for temporary storage and preliminary study.
Residents were repeatedly warned not to handle the debris, which could be toxic. Although there was no immediate evidence of a link, more than 40 people in Nacogdoches County complained of various ailments, and at least eight people were hospitalized with burns and breathing problems in Hemphill, according to Nacogdoches County Judge Sue Kennedy.
Robert Cabana, the director of flight crew operations at the Johnson Space Center in Houston, said NASA was working with the Israeli Embassy to assure that Israeli payload specialist Ilan Ramon's remains are handled properly. Jewish tradition normally calls for burial within 24 hours, followed immediately by mourning rituals.
Other astronauts killed when the spacecraft broke apart returning from a 16-day scientific mission were shuttle commander Rick Husband, mission specialists Michael Anderson, David Brown, Kalpana Chawla and Laurel Clark, and pilot William McCool.
President Bush will honor them at a memorial service tomorrow in Houston.
At a briefing yesterday, Dittemore said that seven minutes before contact with the shuttle was lost, telemetry showed that temperatures in the shuttle's left wheel well had risen 20 to 30 degrees in five minutes.
"This was the first occurrence of a significant thermal event," he said. Other sensors in the area quit working.
Columbia was passing the hottest portion of re-entry, when surface temperatures on the shuttle reach 3,000 degrees Fahrenheit.
As the minutes ticked by, other sensors reported that temperatures in the fuselage - also on the left side - had climbed 60 degrees in five minutes, four times the expected amount. Temperatures in the crew compartment and payload bay remained normal.