STS-51-L was the twenty-fifth flight of the American Space Shuttle program, which marked the first time a civilian had flown aboard the Space Shuttle. The mission used Space Shuttle Challenger, which lifted off from Launch Complex 39-B on January 28, 1986 from Kennedy Space Center in Florida.
The mission ended in disaster following the destruction of Challenger 73 seconds after lift-off. The Rogers Commission, more specifically Dr. Richard P. Feynman, determined the cause was due to the failure of an O-ring seal on Challenger's right Solid Rocket Booster (SRB). The failure of the seal allowed a flamethrower-like flare to impinge upon one of two aft SRB attach struts, which eventually failed, freeing the booster to pivot about its remaining attachment points. Subsequently, the forward part of the booster cylinder impacted the external tank (ET) intertank area, leading to a structural failure of the ET—the core structural component of the entire stack. A rapid burning of liberated propellants ensued. With the structural "backbone" of the stack compromised and breaking up, the SRBs flew off on their own, as did the orbiter, rapidly disintegrating due to the overwhelming aerodynamic forces. Evidence found in the remnants of the crew cabin showed that several of the emergency air supplies (PEAPs) carried by the astronauts had been manually activated, suggesting that the forces during breakup of the orbiter were not inherently fatal and that at least three crew members were alive after the craft broke up.
The tenth mission for Challenger, STS-51-L was scheduled to deploy the second in a series of Tracking and Data Relay Satellites, carry out the first flight of the Shuttle-Pointed Tool for Astronomy (SPARTAN-203)/Halley's Comet Experiment Deployable in order to observe Halley's Comet, and carry out several lessons from space as part of the Teacher in Space Project and Shuttle Student Involvement Program (SSIP). The flight also marked the first American manned mission to involve in-flight fatalities, and the first American manned mission to launch and fail to reach space, the first in the world being Soyuz 18a.
Launch date: January 28, 1986 16:38:00 UTC
Landing: Did not land