The Challenger was nearly nine miles above the Atlantic, traveling at 1,977 mph, when its liquid-fuel tank exploded.


The White House watches the Challenger explosion on television.

It was NASA's 25th space shuttle mission, and Americans were beginning to become complacent about the space program.

In an effort to rekindle interest in the space program, NASA brought on the first civilian in history-a high school social-studies teacher from Concord, New Hampshire.

America huddled around its TV sets to watch Christa McCauliffe, a 37-year-old mother ascend into orbit.

73 seconds after takeoff, the Challenger exploded above Kennedy Space Center in Florida, leaving only its smoky remnants zig zagging through the sky.

The reason for the explosion was a leaky gasket. Engineers had known that O-rings sealing the shuttle's booster rockets grew brittle in the cold. That morning, the thermometer read 36?F. But, the flight was already six days late, and NASA was becoming impatient.

A presidential panel later charged NASA's managers and the O-rings' manufacturer with playing "Russian roulette" with the astronaut's safety.

All seven astronauts aboard were killed, and the space program was grounded for more than two years.