NASA Says Tile Damage Lead Theory

Feb. 3 -- Damage to Columbia's thermal tiles is the leading theory as to why the space shuttle disintegrated minutes before its scheduled landing, but NASA officials said today they are still looking for a "missing link" to help them determine the root cause of the tragedy.

Investigators are trying to determine how a piece of insulation that broke off and hit the left wing of Columbia during its Jan. 16 launch could have possibly caused the shuttle to disintegrate Saturday during its re-entry into the Earth's atmosphere, killing all seven astronauts on board.

NASA investigators have been looking at a sudden spike in temperature and a rise in wind resistance during Columbia's final minutes, both of which suggest the thermal tiles may have been damaged during the launch. Evidence indicates the temperature on Columbia's left side shot up and the craft was buffeted by greater wind resistance, forcing its automatic pilot to quickly change course before it broke up over Texas.

‘We’re Gonna Work Our Darnedest’

At a news briefing this afternoon, shuttle program manager Ron Dittemore said engineering data shows a rise of 30 degrees to 40 degrees in the left wheel well about eight minutes before the spacecraft's last radio transmission. The shuttle temperature rose the normal 15 degrees on the right side over the same period, he said. All the readings came from sensors underneath the thermal tiles, on the aluminum hull of the craft.

NASA officials determined that the piece of broken insulation was approximately 20 by 16 by 6 inches and weighed almost 3 pounds. However, Dittemore said, the temperature rise does necessarily mean there was structural damage to the shuttle. The tiles are supposed to protect the shuttle from the approximately 3,000 degrees of heat generated upon re-entry into the Earth's atmosphere, and Dittemore said the temperature rise should have been more drastic if there was structural damage.

"You can't draw the conclusion from the left main gear or the wheel that we had a breach there," Dittemore said. "If you had a breach there, it seems logical that the temperature would be higher than just 30 or 40 degrees from what we normally expect. These relatively small increases in temperature are telling us something. We're just trying to find out exactly what they're trying to tell us."