Kathryn Thornton was born in Montgomery, Alabama. She received a bachelor's in physics from Auburn University in 1974. Thornton also earned a Master's of Physics in 1977 and a Doctorate of Physics in 1979. Completing her training in 1985, Thornton has spent over 593 hours in space, including 21 hours of spacewalks. On a five-day mission in 1989, she was a mission specialist, orbiting earth seventy-nine times. In 1992, Thornton served the crew onboard the Space Shuttle Endeavour. The Endeavour spent over 200 hours in space on that flight. As a mission specialist, Thornton helped service and repair Hubble in 1993. On her fourth flight, she served as payload commander on Columbia. She is a professor at the University of Virginia and Director at the Center for Science Education, the College of Arts and Sciences, and the Curry School of Education. Thornton has two stepsons and three daughters. Her husband is Stephen Thornton, a physics professor.