7. Peggy Whitson
Though Peggy Whitson grew up on a farm in Iowa, early on, she had set her sights on a career in science. After earning a bachelor of science degree in biology and chemistry, Whitson went on to Houston’s Rice University. There, she earned her doctorate in biochemistry, which would eventually pave her way to NASA.
After completing a postdoctoral fellowship at Rice, Whitson began work at the nearby Johnson Space Center. While there, she served as a National Research Council Resident Research Associate and was head of the Biochemistry Research Group there. In the early nineties, she was also a project scientist for the Shuttle-Mir Program, a collaborative effort between Russian and United States space programs that would have been unthinkable during the Cold War.
Whitson was eventually accepted as an astronaut candidate in 1996, which touched off two years of intensive training. After this, she worked in Russia, in the Aquarius underwater laboratory, and, finally, in orbit around our planet. She first launched into space as part of STS-111 in 2002, as part of the Expedition 5 crew. Her second spaceflight took place in 2007-2008, as part of Expedition 15.
During this mission, Whitson became the first female astronaut to have the most EVAs (Extra-Vehicular Activities, which are typically spacewalks), along with the most cumulative EVA time. As of today, Whitson’s cumulative EVA time stands at 53 hours and 22 minutes. It’s the record for a female astronaut, as well as the 5th place for most EVA time.
However, Whitson isn’t done quite yet. She’s currently in space on the ISS as part of Expedition 50/51. At age 56, she is now the oldest woman to have flown into space. Whitson took over as commander of Expedition 51 on April 10, 2017, her second command role after Expedition 16. She’s also poised to break the record for cumulative time spent in space, previously held by astronaut Jeff Williams at 534 days.