The Challenger disaster occurred on January 28, 1986, when the NASA space shuttle orbiter Challenger broke apart over the Atlantic Ocean 73 seconds into its flight, leading to the deaths of its seven crew members.

Disintegration of the orbiter began after an O-ring seal failed at liftoff. Its failure caused a breach in the joint it sealed, allowing pressurized burning gas from within the solid rocket motor to reach the outside.

Mr. Boisjoly had raised strong objections to the launch the day before the liftoff. Boisjoly correctly predicted, based on earlier flight data, that the O-rings on the rocket boosters would fail if the shuttle launched in cold weather. Temperatures were due to be down to −1 °C.

The accident resulted in an extensive investigation which discovered that as early as 1977, NASA managers had not only known about the flawed O-ring, but that it had the potential for catastrophe.