Space Shuttle Challenger disaster
The mission of the flight that ended in disaster was named STS-51-L. It was the tenth mission for Challenger. STS-51-L was scheduled to deploy the second in a series of Tracking and Data Relay Satellites. It was also going to carry out the first flight of the "Shuttle Pointed Autonomous Research Tool for Astronomy" (SPARTAN-203) / Halley's Comet Experiment Deployable in order to observe Halley's Comet.