Four astronauts were hospitalized after returning to Earth from an eight-month mission to the International Space Station, and one of them remains in the hospital in stable condition.

The astronaut was briefly hospitalized for an unspecified medical issue Friday after returning from a nearly eight-month stay at the International Space Station.

NASA is not yet providing details about what caused a SpaceX Crew-8 astronaut to be hospitalized late last month, citing medical privacy concerns.

Three NASA astronauts whose prolonged space station mission ended with a trip to the hospital last month declined to say Friday which one of them was sick. Astronauts Matthew Dominick, Michael Barratt and Jeanette Epps publicly discussed their spaceflight for the first time since returning from the International Space Station on Oct.

The three NASA astronauts who’d spent seven months living and working on the International Space Station would not disclose which of them spent the night in the hospital once back on U.S. soil during their first press conference since returning to Earth two weeks ago.