The ISS crew had to leave early for the first time due to their health

According to Jared Isaacman, NASA Director, the astronaut remains in stable condition, but the ISS station currently does not have full diagnostic and treatment capabilities. This will be the first medical evacuation in the history of the ISS, which has continuously welcomed rotating crews since November 2000.

The Crew-11 crew includes astronauts Zena Cardman and Michael Fincke (NASA), Kimiya Yui (JAXA Japan Aerospace Exploration Agency) and Oleg Platonov (Russian space agency Roscosmos). They flew to the ISS station with SpaceX’s Crew Dragon Endeavor on August 1, 2025 and are about to end their 6-month mission.

The Crew-11 crew accomplished nearly every mission objective, Isaacman said. Crew-12, the successor crew, consists of 4 people and is expected to fly to the ISS in mid-February. NASA is considering speeding up the process, but it is unlikely that Crew-12 will launch before Crew-11 returns.

NASA first mentioned the issue of astronauts’ health on January 7, when it announced the postponement of the spacewalk, which was scheduled to be performed by Cardman and Fincke on January 8. The agency has not revealed the astronaut’s identity or provided details about health problems for reasons of personal information security.

However, at a press conference on January 8, Dr. James Polk, in charge of NASA’s medical and health department, said the astronaut’s problem was not related to the spacewalk or the preparation process for that activity. “This was not an injury that occurred during the course of the mission, but was primarily a medical problem that arose in the difficult conditions of the microgravity environment and our existing equipment set was not sufficient to diagnose it,” Polk explained.

After the Crew-11 crew leaves and before the Crew-12 group arrives, the ISS may have only three working astronauts left, including Christopher Williams (NASA), Sergey Kud-Sverchkov and Sergei Mikayev (Roscosmos). This trio flew to the ISS station on a Russian Soyuz spacecraft on November 27.

Spacewalking is a difficult and potentially risky activity, requiring astronauts to undergo months of training, wear bulky spacesuits, and strictly follow instructions. In 2024, NASA canceled a spacewalk plan at the last minute because an astronaut felt “uncomfortable with the spacesuit”. In 2021, American astronaut Mark Vande Hei also canceled his walk due to nerve compression.