February 1, 2003, Space Shuttle Columbia disaster. Shortly before it was scheduled to conclude it's 28th mission, the Space Shuttle Columbia disintegrated over Texas and Louisiana during re-entry into the Earth's atmosphere. All seven crew members were killed.
Just 73 seconds after liftoff, the Space Shuttle Challenger explodes in a horrifying cloud of smoke and debris on Jan. 28, 1986. Seven crew members on board died. The cause was later blamed on a failed O-ring on a solid rocket booster.