That signal was relayed to Mission Control. It was too small to cause alarm.

Nine and a half minutes after leaving orbit, Columbia streaked over California, trailing flashes of sparks.

Thermal tiles and pieces of the upper side of the wing were peeling away like shingles in a hurricane.

Ten times in 10 seconds, bright bursts of glowing particles flashed in Columbia's wake.

Passing over Texas, Columbia was wobbling enough that all four of its maneuvering jets fired automatically in an effort to stabilize it.

The shuttle rolled violently to the right. It yawed violently to the left.

At Mission Control, Marine Lt. Col. Charles Hobaugh, the astronaut in charge of communications, radioed the crew about the telemetry data.

"Columbia, Houston. We see your tire pressure messages and we did not copy your last call."

"Roger," replied shuttle commander Husband. "Uh, buh …. "

His transmission ended in mid-word.

Gyrating wildly, Columbia was traveling at 12,738 mph.

A large piece of the spacecraft ripped off. Five more pieces wrenched free during the next 30 seconds.

Half of the left wing broke away.

A final burst of telemetry data suggested that the autopilot toggled off and on.

Seconds after 9 a.m. EST, the onboard recorder stopped.

Several hundred miles later, the remaining root of the left wing ripped away.

Pulled around like a shuttlecock by the weight of its heavy main engines, the craft started flying tail first.

Almost immediately, the tail structure and engines snapped off.

Seconds later, the right wing broke away.

The crew compartment briefly continued to fly on its own, then was torn apart.