Nasa has decided to return a four-person International Space Station crew a month early due to a serious medical condition affecting one astronaut.
The agency said the astronaut is in a stable condition but declined to disclose further details for privacy reasons.
This is not an emergency evacuation. We always err on the side of the astronaut's health.
A Nasa official said.
A planned spacewalk was cancelled earlier this week after Nasa cited a medical concern.
Nasa Administrator Jared Isaacman said the medical issue was not related to space operations and was not caused by an injury.
The early return marks the first time in the ISS’s history that a mission has been cut short for medical reasons.
Crew-11 includes Nasa astronauts Zena Cardman and Mike Fincke, Japan’s Kimiya Yui and Russian cosmonaut Oleg Platonov.
One US astronaut will remain on the ISS alongside two Russian cosmonauts after the crew’s departure.
Nasa said an update on the crew’s return timeline would be provided within 48 hours.
Experts said some scientific experiments and maintenance work may be delayed until the next crew arrives.