An American astronaut is hospitalized after returning to Earth after spending nearly eight months on the International Space Station (ISS), NASA announced.

The US space agency did not reveal the astronaut’s identity or why he remained in the hospital, citing “medical confidentiality”.

In any case, this is one of three Americans on SpaceX’s Crew-8 mission. Matthew Dominik, Michael Barratt and Janet Epps returned to Earth Thursday night into Friday aboard a SpaceX Dragon spacecraft after spending 232 days on the ISS. The Russian cosmonaut Alexander Gebenkin was also a member of the mission.

After the rocket grounded off Florida, NASA said an astronaut experienced a “medical problem.” All were taken to a hospital in Pensacola, tested and all three were released and have already arrived at the Johnson Space Center in Houston, Texas. The lone astronaut who remained hospitalized is “in stable condition and being monitored as a precaution,” NASA said.