Expedition 51

Expedition 51 was a 2017 International Space Station increment commanded by NASA astronaut Peggy Whitson. It began after Soyuz MS-02 departed with the Expedition 50 return crew, leaving Whitson, Oleg Novitsky, and Thomas Pesquet aboard the station. Soyuz MS-04 then arrived with Fyodor Yurchikhin and Jack Fischer, bringing the resident crew to five. The increment supported human health, biology, combustion, Earth observation, and technology investigations, as well as visiting-vehicle operations around Cygnus OA-7 and Dragon CRS-11. The crew also carried out U.S. segment spacewalks to replace and prepare external station hardware, including avionics and docking-system support work. Expedition 51 ended when Soyuz MS-03 undocked with Novitsky and Pesquet, while Whitson stayed aboard and continued as part of Expedition 52.