Kathryn Dwyer Sullivan (born October 3, 1951) is an American geologist and a former NASA astronaut. A crew member on three Space Shuttle missions, she was the first American woman to walk in space on October 11, 1984. On June 7, 2020, she became the first woman to dive to the Challenger Deep in the Mariana Trench, the deepest part of the Earth’s oceans