The Space Shuttle Challenger disaster was a fatal accident in the United States' space program that occurred on January 28, 1986, when the Space Shuttle Challenger broke apart 73 seconds into its flight, killing all seven crew members aboard. The mission carried the designation STS-51-L and was the tenth flight for the Challenger orbiter.
The spacecraft disintegrated over the Atlantic Ocean, off the coast of Cape Canaveral, Florida, at 11:39 a.m. EST. The disaster began after a joint in the Space Shuttle's right solid rocket booster failed at liftoff. The failure was caused by the failure of O-ring seals used in the joint, in part because of the unusually cold temperatures at the time of launch. The seals' failure caused a breach in the SRB joint, which allowed pressurized burning gas from within the solid rocket motor to reach the outside and impinge upon the adjacent SRB's aft field joint attachment hardware and external fuel tank. This led to the separation of the right-hand SRB's aft field joint attachment and the structural failure of the external tank. Following the explosion, the orbiter was broken up by aerodynamic forces.