Three American astronauts and a Russian cosmonaut have been taken to a medical facility after returning to Earth from a nearly eight-month mission on the International Space Station.
NASA astronauts Matthew Dominick, Michael Barratt, and Jeanette Epps, and Russian cosmonaut Alexander Grebenkin "were taken to a local medical facility for additional evaluation," NASA said in a statement following their splashdown in the Crew Dragon spacecraft at 3.29am local time on Friday (8.29am UK time) off Florida's Gulf Coast.
The space agency said the crew had their standard medical evaluations upon exiting the craft, but added that "out of an abundance of caution, all crew members were flown to the facility together".
NASA, which is usually tight-lipped on medical issues involving astronauts, declined to say what prompted the abundance of caution or describe the crew's condition.
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Russia's space agency has not responded to a request for comment on Mr Grebenkin's condition.
SpaceX has a fleet of reusable spacecraft and has flown to the ISS 44 times.
The Elon Musk-owned company remains the only US option for NASA astronaut trips to and from the space station. Boeing's Starliner, intended as a second US ride, has been hindered by years of development issues.
The crew should have been back on Earth two months ago but their homecoming was stalled by problems with the Starliner astronaut capsule, which returned empty in September because of safety concerns.
Hurricane Milton then interfered, followed by a further two weeks of high wind and rough seas.
Marking 235 days in space, the Crew-8 astronauts' stay aboard the ISS, a football field-sized science lab 250 miles in orbit, was longer than the typical six-month astronaut missions on the station.
It also marked the longest mission so far for SpaceX's Crew Dragon spacecraft since its introduction in 2020.
Following the series of delays, the Crew Dragon spacecraft safely undocked from the ISS on Wednesday and re-entered Earth's atmosphere early Friday morning, deploying parachutes before dropping into the Gulf of Mexico.
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At a post-splashdown news briefing, a NASA official said "the crew is doing great" and made no mention of any issues with the astronauts, but noted two hitches with Crew Dragon's parachute deployment.
Richard Jones, deputy manager of NASA's Commercial Crew Program, said Crew Dragon's initial set of braking parachutes suffered some "debris strikes" and that one of four parachutes in a subsequent set took longer than expected to unfurl.
Neither event affected crew safety, Mr Jones said, calling the splashdown weather "ideal" for the crew's recovery.