Four space station crewmates boarded their Crew Dragon ferry ship Wednesday and undocked kick off an expedited return to Earth on Thursday, cutting their mission short because of an undisclosed medical issue.

Four astronauts are on their way home to Earth on Thursday after an earlier-than-scheduled departure from the International Space Station. NASA officials called it a “controlled medical evacuation,” the first time in 25 years an astronaut left the I.S.S. for this reason.

The SpaceX Dragon spacecraft is set to splash down off Southern California following a rare medical evacuation from orbit.

Four astronauts are set to depart the International Space Station Wednesday amid a health concern. The unprecedented early departure will leave behind a skeleton crew.

The research has implications for NASA’s goals to build a base on the moon and eventually conduct crewed missions to Mars.

'Backward and upward and tilted': Spaceflight causes astronauts' brains to shift inside their skulls Spaceflight doesn't just change your perspective — it shifts the actual position of your brain inside your skull, a new study reports.