Dr. Peggy Whitson, an Iowa biochemist, joined NASA’s astronaut corps in 1996. She would become the most experienced American astronaut of either gender. Across three long-duration missions to the International Space Station—Expedition 5 (2002), Expedition 16 (2008), and Expeditions 50–52 (2016–2017)—she accumulated 665 days in space, a U.S. record. She was the first female commander of the ISS on Expedition 16, and the first woman to command it twice on Expedition 51. She performed ten spacewalks totaling over 60 hours, another record for women. In 2009, between her second and third long-duration missions, she became NASA’s first female Chief of the Astronaut Office—and the first non-military chief. After retiring from NASA in 2018, she joined Axiom Space and commanded the Ax-2 private mission to the ISS in 2023, becoming the first woman to command a private spaceflight. She was 63. She has spent more of her life in space than any other American.