An astronaut was taken to hospital shortly after returning to Earth from an extended mission on the International Space Station.
The astronaut, who NASA did not name for privacy reasons, is suffering from an undisclosed medical issue.
NASA initially said the entire crew was flown to Ascension Sacred Heart Pensacola hospital out of precaution, but did not specify whether all or some of the crew had been experiencing issues.
The other three crew members have left the hospital and returned to Houston, the space agency said.
NASA said: “The one astronaut who remains at Ascension is in stable condition under observation as a precautionary measure.”
Astronauts Matthew Dominick, Michael Barratt, and Jeanette Epps, and Russian cosmonaut Alexander Grebenkin splashed down in a SpaceX Dragon spacecraft at 3.29am local time on Friday (8.29am UK time) off Florida’s Gulf Coast.
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.
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.
Support teams with the SpaceX Dragon Endeavour spacecraft shortly after it landed in the Gulf of Mexico off the coast of Florida. Pic: NASA via AP
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 on Friday morning, deploying parachutes before dropping into the Gulf of Mexico.
Keep up with all the latest news from the UK and around the world by following Sky News
Read more:
SpaceX arrives at ISS to rescue stranded astronauts
Faulty spacecraft heading back to Earth
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 Programme, 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.