Shannon Walker (born 4 June 1965 in Houston, Texas) is an American scientist and a NASA astronaut, whose first space mission was Expedition 24 on the International Space Station with take-off on 15 June 2010. She is married to a fellow NASA astronaut, the Australian-born Andy Thomas. She is a member of the Aircraft Owners and Pilots Association (AOPA) and The Ninety-Nines International Organization of Women Pilots.