US astronaut and physician. His two space shuttle flights include the Discovery mission of February 1995, as payload commander, when he became the first African American to undertake a space walk. He logged more than 438 hours in space before leaving NASA in 1996 to become chief scientist and vice-president of Science and Health Services. He joined the Johnson Space Center in 1987 as a clinical scientist and flight surgeon, and was selected as an astronaut in 1990.
Subjects: Astronomy and Astrophysics.