Peggy Whitson, PhD, is a biochemistry researcher and a retired NASA astronaut. She has spent 675 days in space, more than any other American or woman, placing her eighth on the all-time space endurance list. Her career has been filled with a surfeit of firsts. Whitson was the first woman commander of the International Space Station, and the only woman to serve as International Space Station commander twice. She was the first woman, and first non-pilot to serve as Chief of the NASA Astronaut Office. She is the first woman to complete 10 space walks, and the first woman to command a private space mission with Axiom Space.