Nasa is cutting short a mission aboard the International Space Station after an astronaut had a medical issue.

The space agency said Thursday the US-Japanese-Russian crew of four will return to Earth in the coming days, earlier than planned.

Nasa canceled its first spacewalk of the year because of the health issue. The space agency did not identify the astronaut or the medical issue, citing patient privacy. The crew member is now stable.

“It’s not an emergency evacuation, but we are erring on the side of caution for the crew member,” said Dr James Polk, Nasa’s chief health and medical officer.

The crew of four arrived at the orbiting lab via SpaceX in August for a stay of at least six months. The crew included Nasa’s Zena Cardman and Mike Fincke along with Japan’s Kimiya Yui and Russia’s Oleg Platonov.

Fincke and Cardman were supposed to carry out the spacewalk to make preparations for a future rollout of solar panels to provide additional power for the space station.

It was Fincke’s fourth visit to the space station and Yui’s second, according to Nasa. This was the first spaceflight for Cardman and Platonov.

“I’m proud of the swift effort across the agency thus far to ensure the safety of our astronauts,” Nasa administrator Jared Isaacman said.

Three other astronauts are currently living and working aboard the space station, including Nasa’s Chris Williams and Russia’s Sergei Mikayev and Sergei Kud-Sverchkov, who launched in November aboard a Soyuz rocket for an eight-month stay. They are due to return home in the summer.

Nasa has tapped SpaceX to eventually bring the space station out of orbit by late 2030 or early 2031; plans call for a safe re-entry over ocean.