Columbia recorder shows temperatures surging earlier

SPACE CENTER, Houston -- A tape recorder from the shattered Columbia shows temperatures surging inside the left wing three minutes earlier -- and hundreds of degrees higher -- than previously detected during the final portion of the shuttle's doomed flight, the chief investigator said Monday.

The preliminary finding is based on "just two little data points out of the hundreds that we're going to get here," said Harold Gehman Jr., chairman of the Columbia Accident Investigation Board. Nonetheless, it indicates "the orbiter probably had this problem before she ever started her entry" and that this problem was on or very near the leading edge of the left wing.

This same area was struck by foam and possibly other debris that broke off Columbia's external fuel tank during the January liftoff. Gehman said he's hoping the salvaged tape provides clues as to the vibration and forces exerted on the left wing, as well as an unusually strong wind shear experienced by the space shuttle moments before the debris scraped the wing at 500 mph.

Given Columbia's altitude when the first sign of trouble was detected during its plunge back to Earth -- the space shuttle was about 270,000 feet high and traveling about Mach 25, or 25 times the speed of sound -- Gehman said air pressure would not have been enough to dislodge a protective carbon panel or anything else on the shuttle's wing.

Gehman cautioned that just because a sensor registered off-the-scale temperatures right around one particular carbon panel on the leading edge of the wing, that does not mean that's where the breach occurred. The latest information does not contradict the so-called footprint put forth by the investigation board last week as the most likely area where the launch debris hit, he said.

"We are still pulling all the data together to attempt to indicate where the breach is," he told reporters. "But this certainly leads us away from things like tile and landing gear doors and things like that. It kind of leads us toward the leading edge."

The data recorder -- found on a muddy slope in East Texas two weeks ago -- contained thousands of feet of magnetic tape full of temperature, pressure, vibration and other measurements from Columbia's catastrophic descent through the atmosphere on Feb. 1.

"It's a treasure trove of data," Gehman said.

The first spike in temperature -- detected by a sensor behind one of the carbon heat-protective panels on the leading edge of the left wing -- occurred five minutes after Columbia first encountered the atmosphere, high above the Pacific. Until now, the first sign of overheating had been in the left main landing gear compartment, eight minutes after the encounter with the atmosphere.

This sensor behind the carbon panel was designed to record only up to 450 degrees, and so it shot up that far and then failed, possibly because of the searing atmospheric gases burning through its wires, Gehman said. Just as that sensor went off-line, another sensor buried deeper inside the wing began to indicate rising temperatures, "which would lead you to believe that there was a whole lot of heat ... which finally ate its way into the wing," he said.

Around the same time, temperature sensors on the skin of the left orbital maneuvering engine pod at the tail of the spaceship began to do "all kinds of strange things," Gehman said. Some of them shot up and some went down, while some went down and rose later and vice versa.

The tape contains data that extend eight seconds beyond the final signal that was transmitted from Columbia to ground controllers, Gehman said. Far more interesting to investigators, however, is what happened early in the descent, he said.

"We know what happens at the back end," he said.

All seven astronauts were killed when Columbia disintegrated over Texas, just minutes short of their planned Florida homecoming.

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