Flight directors Jay H. Greene (foreground) and Alan L. Briscoe (background) in the flight control room of the Johnson Space Center's Mission Control Center during the Space Shuttle Challenger launch. Challenger exploded 73 seconds after lift-off from Kennedy Space Centre, Florida, USA on 28 January 1986. The explosion occurred as a result of a failure of one of the O-rings in a seal on one of the booster rockets. A subsequent leakage of fuel triggered the explosion that killed all seven crew members.