Expedition 52 is the 52nd expedition to the International Space Station. It officially began on June 2, 2017 10:47 UTC, with the undocking of Soyuz MS-03. Transfer of Command from Expedition 51 was done on June 1st, 2017.
Due to a decision to cut down the number of participating Russian cosmonauts in 2017, only two crew members were launched on Spyuz MS-04, which brought the ISS total crew down to five people. However, it was later decided that Peggy Whitson would stay on board longer, transferring from Expedition 51 to maintain a full crew of six astronauts over the summer, after the arrival of three new members on Soyuz MS-05.