NASA will return four astronauts to Earth early from the International Space Station due to a medical concern with one of the Crew-11 astronauts.

NASA and SpaceX are targeting no earlier than 5 p.m. EST, Wednesday, Jan. 14, for the undocking of the agency’s SpaceX Crew-11 mission from the International Space Station, pending weather conditions.

NASA did not identify the crew member or provide details on the medical concern, citing privacy issues in a brief blog post.