7 March 1986

Challenger Disaster: Divers from the USS Preserver locate the crew cabin of Challenger on the ocean floor.

The Challenger shuttle disaster was caused by the failure of a seal on one of the solid rocket boosters (SRBs), which allowed hot gases and flames to escape and damage the external fuel tank, leading to the catastrophic breakup of the shuttle.

More specifically, the failure of the O-ring seal in the joint between the two lower segments of the right SRB was the primary cause of the disaster. The O-ring failed to seal properly due to several factors, including the low temperature at the time of launch, which made the rubber more brittle and less resilient, and the design of the joint, which made it susceptible to erosion and blow-by.

The decision to launch the Challenger despite concerns about the O-ring’s performance in cold weather, and a lack of communication between NASA and the contractor responsible for the SRBs, also contributed to the disaster.

Tragically, all seven crew members, including the first civilian teacher in space, Christa McAuliffe, were killed in the explosion. The Challenger disaster was a devastating reminder of the risks and complexities of human spaceflight, and led to significant changes in NASA’s safety culture and procedures.