Video footage released by Nasa on Wednesday showed four astronauts undocking from the International Space Station, marking the agency’s first-ever medical evacuation from orbit. The crew, two Americans, a Russian cosmonaut, and a Japanese astronaut, departed aboard a SpaceX capsule after one of the astronauts required doctors’ care, prompting an early return that cuts short their mission by more than a month.The returning astronauts are Americans Mike Fincke and Zena Cardman, Russian cosmonaut Oleg Platonov, and Japanese astronaut Kimiya Yui. After spending five months aboard the ISS, they are scheduled to splash down in the Pacific Ocean near San Diego early Thursday morning.“Our timing of this departure is unexpected,” Nasa astronaut Zena Cardman said ahead of the return trip, “but what was not surprising to me was how well this crew came together as a family to help each other and just take care of each other.”Nasa officials have declined to identify the astronaut who required medical care last week and have not disclosed any details of the health issue.The ailing astronaut is “stable, safe, and well cared for,” outgoing International Space Station commander Mike Fincke said earlier this week through a social media post.“First and foremost, we are all OK. Everyone on board is stable, safe, and well cared for,” Fincke said, adding that it was a “deliberate decision to allow the right medical evaluations to happen on the ground, where the full range of diagnostic capability exists. It’s the right call, even if it’s a bit bittersweet.”The four-member Crew-11 mission arrived at the International Space Station in early August and had been scheduled to remain there until mid-February, when the next crew was due to take over. However, concerns over an astronaut’s health prompted NASA to bring the team back more than a month earlier than planned.James Polk, Nasa’s chief health and medical officer, said the decision was driven by a “lingering risk” and a “lingering question as to what that diagnosis is.” Officials stressed that the medical issue was not related to spacewalk preparations or other station operations and said it did not constitute an emergency. No further details were provided, citing medical privacy.Nasa said standard re-entry and splashdown procedures would be followed, with a full team of medical specialists aboard the recovery ship in the Pacific. The return marked another overnight crew recovery for SpaceX, occurring less than 11 hours after undocking from the space station. Nasa added that it was not yet clear how soon the astronauts would be transported from California to Houston, home to the Johnson Space Center and the astronauts’ base.One American and two Russian astronauts remain aboard the space station, just six weeks into an eight-month mission that began with a Soyuz launch from Kazakhstan. Nasa and SpaceX are now working to advance the launch of a new four-member crew from Florida, currently scheduled for mid-February.While computer modelling had anticipated the possibility of a medical evacuation from the ISS roughly once every three years, Nasa said this marks the first such evacuation in its 65-year history of human spaceflight.