NASA said it will return a four-person crew aboard the International Space Station (ISS), cutting their mission a month early due to the “serious health condition” of one of the astronauts.
The agency did not release the crew member's name or medical condition, citing confidentiality, but said the man was in stable condition.
“This is not an emergency evacuation,” a NASA spokesman said, adding: “We always err on the side of astronaut health.”
On Wednesday, NASA abruptly canceled Thursday's spacewalk, when two astronauts were scheduled to leave the ISS, citing “medical concerns.”
The decision to return the crew early was announced by NASA Administrator Jared Isaacman and other agency officials at a news conference on Thursday.
They provided few details but noted that the health problem was not related to space operations and was not an injury.
They added that an update on the astronauts' return schedule is expected within 48 hours.
The four-person team is called “Crew 11” and consists of NASA astronauts Zena Cardman and Mike Finke, Kimiya Yui of the Japanese space agency JAXA and Russian cosmonaut Oleg Platonov.
One American astronaut will remain aboard the ISS, officials said.
Crew 11 was launched to the ISS last August on the SpaceX Crew Dragon and is expected to remain in orbit for about six months and return around next month after being replaced by another four-member crew a few days earlier.
The ISS has essential medical equipment, supplies and communications systems that allow doctors on Earth to speak confidentially with astronauts in space, assess their condition and make treatment recommendations, much like a secure video or telephone consultation with a general practitioner.
The early return of the four-person crew could delay some experiments and maintenance tasks until the new crew arrives next month, according to Dr Simeon Barber, a space scientist at the Open University.
“The space station is a large and complex engineering project and is designed to be operated by a certain minimum level of crew,” he said.
He added that the remaining crew will likely have to “return to some experimental work and focus only on housekeeping and maintaining the station operational while waiting for the full crew to be restored.”
