US astronaut. His three space shuttle missions included piloting Challenger in April 1985 on a Spacelab flight. Gregory joined NASA's Langley Research Center as a research test pilot in 1975, was selected as an astronaut in 1978, and joined NASA's headquarters in Washington, DC, in 1992 as associate administrator of the Office of Safety and Mission Quality. In 2002 he became NASA's deputy administrator in Washington, DC.
Subjects: Astronomy and Astrophysics.