NASA said it would be bringing four astronauts home from the International Space Station more than a month early because of a medical issue.
The agency made the announcement on Thursday after it had to postpone a planned spacewalk meant to take place that same day, per NBC News.
NASA did not give additional information about the medical issue, such as the identity of the crew member affected and the nature or severity of the medical issue, but did clarify that only one crew member is affected and that they are in stable condition, per CBS News.
“After discussions with chief health and medical officer Dr. JD Polk and leadership across the agency, I’ve come to the decision that it’s in the best interest of our astronauts to return Crew-11 ahead of their planned departure,” NASA Administrator Jared Isaacman said at a news briefing.
It is very rare for astronauts to be brought back to Earth earlier than planned. The returning astronauts are part of the Crew-11 mission.
The Crew-11 mission carrying four astronauts launched to the space station on Aug. 1, aboard a SpaceX Crew Dragon capsule, per NBC News. The astronauts include NASA astronauts Zena Cardman and Mike Fincke, Japanese astronaut Kimiya Yui and Russian cosmonaut Oleg Platonov.
As part of their mission, the astronauts are conducting studies to assess how the health of astronauts could be affected by deep space travel. The studies include researching how the body processes B vitamins in space and how body fluids are redistributed during weightlessness, per The New York Times.
The four were supposed to remain aboard the station until late February, making it a six-month stay.
Crew-11 is SpaceX’s latest astronaut mission, per Space.com.
There are three additional astronauts currently living on the International Space Station: NASA astronaut Christopher Williams and cosmonauts Sergey Kud-Sverchkov and Sergei Mikayev, according to The New York Times. They arrived at the orbiting laboratory on Nov. 27, aboard a Russian Soyuz spacecraft.