The Space Shuttle Discovery, damaged during liftoff, disintegrated during the point of re-entry into the Earth's atmosphere. All seven astronauts died. http://www.pbs.org/newshour/bb/science/columbia/
In June 1974, Gregory was detailed to the NASA Langley Research Center, Hampton, Virginia. He served as a research test pilot at Langley until selected for the Astronaut Program in January 1978. http://www.jsc.nasa.gov/Bios/htmlbios/gregory-fd.html