Japan’s Kimiya Yui and three other astronauts will return from the International Space Station earlier than scheduled due to a crew member’s medical issue, the U.S. space agency NASA has said.

The ISS crew members are set to return to Earth aboard a U.S. Crew Dragon spaceship within a few days. The move marks the first early return from the ISS due to illness.

Yui is not the crew member dealing with a health issue, the Japan Aerospace Exploration Agency said.

NASA said the condition of the astronaut with a medical issue is stable but that it decided that they should be returned to Earth.

Details of the schedule will be announced within a day or two.

Yui, who departed Earth last August with U.S. and Russian astronauts aboard the Crew Dragon spacecraft, had been scheduled to stay on the ISS for about six months.