January 28, 1986. On today’s date, the Space Shuttle Challenger (mission STS-51-L) exploded and broke apart 73 seconds into its flight, after an O-ring seal in its right solid rocket booster (SRB) failed at liftoff. The explosion led to the deaths of all seven Challenger crew members. The spacecraft disintegrated over the Atlantic Ocean, off the coast of central Florida at 11:38 EST (16:38 UTC).
Front row, from left to right: Michael J. Smith, Dick Scobee, Ronald McNair
Back Row – Ellison Onizuka, Christa McAuliffe, Gregory Jarvis, Judith Resnik
The O-ring failure caused a breach in the SRB joint it sealed, allowing pressurized hot gas from within the solid rocket motor to reach the outside and impinge upon the adjacent SRB attachment hardware and external fuel tank. This led to the separation of the right-hand SRBs aft attachment and the structural failure of the external tank. Aerodynamic forces promptly broke up the orbiter.