ISS astronauts splash down to Earth after first-ever medical evacuation

Footage from NASA showed four International Space Station (ISS) crew members splash down in the Pacific Ocean on Thursday, following the first medical evacuation in the station's 25-year history.

The capsule carrying American astronauts Mike Fincke and Zena Cardman, Russian cosmonaut Oleg Platonov and Japanese astronaut Kimiya Yui landed off the coast of San Diego around 0841 GMT.

"On behalf of SpaceX and NASA, welcome home," mission control radioed.

"It's so good to be home, with deep gratitude to the teams that got us there and back," Cardman replied.

The Crew-11 mission was cut short after five months due to a crew member's health issue. NASA has not disclosed specifics but stressed that the return was not an emergency.

The affected crew member "is doing fine," NASA Administrator Jared Isaacman said, describing the issue as "a serious medical condition" that "could have happened on Earth completely outside of the microgravity environment."

He confirmed all crew are safe, in good spirits and undergoing standard post-arrival medical checks.

Pilot Mike Fincke confirmed that "everyone on board is stable, safe, and well cared for," noting the return allowed for proper medical evaluation on Earth, where a full range of diagnostic capabilities exist.

The quartet had arrived at the ISS in early August and was scheduled to remain until mid-February.

According to NASA's chief health and medical officer, James Polk, the decision was prompted by a "lingering risk" associated with the medical issue.

While astronauts train for minor medical issues, including motion sickness, headaches, dental emergencies and kidney stones, and the ISS carries some equipment, it has no doctor on board, making this evacuation "a serious test of NASA's procedures for dealing with medical issues," the BBC reported.

This marks only the third time a mission was cut short for health reasons. The previous two were in 1985, when Soviet cosmonauts were evacuated early from the Salyut 7 space station, and in 1987, when cosmonauts made an early return from the Mir space station.

(With input from agencies.)