Four astronauts are hours away from strapping into a spacecraft and departing the International Space Station about a month early after one of them experienced a health issue. The impending departure would mark the first time in the station's 25-year history that a crew on the orbital outpost has cut a mission short in order to be medically evacuated.

Four astronauts have closed their spacecraft hatch and are leaving the outpost about a month earlier than scheduled because a crew member, who was not identified, has an undisclosed medical issue.