American scientist and astronaut who flew as a payload specialist on two NASA Space Shuttle missions in 1997. Bachelor of science in physics from Tennessee Polytechnic Institute, 1962; master of science in physics from Virginia Polytechnic Institute, 1968; Ph.D. in physics from Virginia Polytechnic Institute, 1971; was selected as backup for missions of STS-42 and STS-64; since 1985 Chief Scientist of the NASA Microgravity Space and Applications Division.