US astronauts Anne McClain and Nichole Ayers, Japan's Takuya Onishi and Russian cosmonaut Kirill Peskov are expected to spend more than 17 hours in the capsule before splashing down off California's coast at 1533 GMT on Saturday.

Their return will mark the end of the 10th crew rotation mission to the space station under NASA's Commercial Crew Program, which was created to succeed the Space Shuttle era by partnering with private industry.

The Dragon capsule of billionaire Elon Musk's SpaceX company detached from the International Space Station (ISS) at 2215 GMT on Friday.

The capsule's dizzying drop back down to Earth will be slowed when it re-enters the atmosphere -- and then again by huge parachutes to soften its landing.

After the capsule splashes down, it will be recovered by a SpaceX ship and hoisted aboard.

Only then will the astronauts be able to breathe Earth's air again, for the first time in months.

The astronauts, known as Crew-10, conducted numerous scientific experiments during their time on the space station, including studying plant growth and how cells react to gravity.

Their launch into space in March was heavily scrutinized because it finally allowed two US astronauts -- who had been unexpectedly stuck onboard the space station for nine months -- to return home.

When they launched in June 2024, Butch Wilmore and Suni Williams were only supposed to spend eight days in space on a test of the Boeing Starliner's first crewed flight.

However, the spaceship developed propulsion problems and was deemed unfit to fly back, leaving them stranded in space.

NASA announced this week that Wilmore has decided to retire after 25 years of service at the US space agency.

Last week, US astronauts Zena Cardman and Mike Fincke, Japan's Kimiya Yui and Russian cosmonaut Oleg Platonov boarded the ISS for a six-month mission.

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