19. Kathryn D. Sullivan
Kathryn D. Sullivan is a geologist and former astronaut who holds the distinction of being the first American woman to walk in space. However, her career began with a more down-to-earth passion: geology.
Specifically, Sullivan holds a PhD in Geology from Dalhousie University, awarded in 1978. Like many astronauts both before and after her, Sullivan spent a considerable amount of time in the ocean. She was a member of numerous expeditions that studied the ocean floors of both the Pacific and the Atlantic.
In 1988, ten years after receiving her doctorate, Sullivan joined the U.S. Naval Reserve as an oceanography officer. However, her duties there were put on hold when she was accepted into astronaut training at NASA. On her first flight, the 1984 STS-41-G mission, Sullivan became the first American woman to undertake an extra-vehicular activity (EVA).
Later, Sullivan studied the effects of weightlessness and magnetic fields on ion arcs, as well as crystal growth and the behavior of polymer membranes in space. On STS-45, she served as Payload Commander, which included operation of ATLAS-I (Atmospheric Laboratory for Applications and Science), an important data-gathering tool.
Since her retirement from NASA in 1993, Sullivan has served as director of COSI, the Columbus Science Center and, later, the Assistant Secretary of Commerce for Environmental Observation and Prediction under the Obama presidential administration. She also served as Under Secretary of Commerce for Oceans and Atmosphere and NOAA Administrator.