Kathryn Thornton (born 1952), American astronaut. Thornton obtained a bachelor's degree in physics (Auburn University) and a master's in physics (University of Virginia, 1977) before taking a PhD in physics in 1979. She then worked at the Max-Planck-Institut for Nuclear Physics in Germany, before returning to the USA to train as an astronaut in 1984. She acted as Mission Specialist on Shuttle flights STS-33 (1989), STS-49 (1992), STS-61 (1993). On the STS-73 (1995), Thornton served as payload commander of the second United States Microgravity Laboratory mission. Thornton retired from NASA in 1996.