Four astronauts from NASA`s Crew-10 mission departed the International Space Station on Friday aboard a SpaceX Dragon capsule, heading for a splashdown off the US West Coast on Saturday morning after a five-month crew rotation mission at the orbiting lab.

US astronauts Nichole Ayers and Anne McClain, the Crew-10 commander, boarded the gumdrop-shaped Dragon capsule on Friday afternoon along with Japanese astronaut Takuya Onishi and Russian cosmonaut Kirill Peskov ahead of a 17.5-hour trek back to Earth to a splashdown site off the California coast.

The four-person crew launched to the ISS on Mar 14 in a routine mission that replaced the Crew-9 crew, which included NASA astronauts Butch Wilmore and Suni Williams, the astronaut pair left on the station by Boeing`s Starliner capsule.

Five months after the Starliner mission`s conclusion, Wilmore this week retired from NASA after a 25-year career in which he flew four different spacecraft and logged a total of 464 days in space. Wilmore was a key technical adviser to Boeing`s Starliner programme along with Williams, who remains at the agency in its astronaut corps.

The four astronauts in the Crew-10 capsule are scheduled for a splashdown in the Pacific Ocean at 11:33am ET (1533 GMT) Saturday.

NASA said they are returning to Earth with "important and time-sensitive research" conducted in the microgravity environment of the ISS during the 146-day mission. The astronauts had over 200 science experiments on their to-do list.