The Space Shuttle Challenger disaster occurred on January 28, 1986, when the NASA Space Shuttle orbiter Challenger exploded 73 seconds into its flight, leading to the deaths of its seven crew members, which included five NASA astronauts and two Payload Specialists. The spacecraft disintegrated over the Atlantic Ocean, off the coast of Cape Canaveral, Florida, at 11:39 EST. Disintegration of the vehicle began after an O-ring seal in its right solid rocket booster failed at liftoff. The O-ring failure caused a breach in the SRB joint it sealed, allowing pressurized burning gas from within the solid rocket motor to reach the outside and impinge upon the adjacent SRB 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. Aerodynamic forces broke up the orbiter.

The mission’s launch from Kennedy Space Center at Cape Canaveral, Florida, was delayed for six days due to weather and technical problems. The morning of January 28 was unusually cold, and engineers warned their superiors that certain components—particularly the rubber O-rings that sealed the joints of the shuttle’s solid rocket boosters—were vulnerable to failure at low temperatures. However, these warnings went unheeded, and at 11:39 a.m. Challenger lifted off.

Seventy-three seconds later, hundreds on the ground, including the families of McAuliffe and the other astronauts on board, stared in disbelief as the shuttle exploded in a forking plume of smoke and fire. Millions more watched the wrenching tragedy unfold on live television. Within instants, the spacecraft broke apart and plunged into the ocean, killing its entire crew, traumatizing the nation and throwing NASA’s shuttle program into turmoil.