Expedition 51 is the 51st expedition to the International Space Station. Peggy Whitson, Oleg Novitskiy and Thomas Pesquet will be transferred from Expedition 50. Peggy Whitson is the intended commander of Expedition 51, the first woman to command two expeditions to the ISS, having previously commanded Expedition 16.
Due to a decision to cut down the number of participating Russian astronauts in 2017, only two astronauts will be launched on Soyuz MS-04, bringing the total crew number to five. The Interagency Commission of the State Corporation Roscosmos has approved the lists of the main and backup crews of expeditions to the International Space Station (ISS) in 2017: Fyodor Yurchkhin, ISS-51 flight engineer, ISS-52 commander and Jack Fischer, ISS-51, ISS-52 flight engineer.
