NASA astronaut describes ISS experience that led to its first-ever evacuation

A NASA astronaut who prompted the space agency's first medical evacuation from the International Space Station (ISS) has opened up on the terrifying experience.

Back in January, NASA said a 'single crew member on board the station' had 'experienced a medical situation' and that the team of astronauts would be heading home earlier than planned.

NASA did not officially announce the identity of the crew member, but off the back of a request from the astronaut in question, the person who experienced the 'medical emergency' was later detailed to be Mike Fincke.

After NASA and SpaceX worked together to bring the crew home in the SpaceX Dragon capsule, Fincke provided further context on what lead to the evacuation.

"Thanks to their quick response and the guidance of our NASA flight surgeons, my status quickly stabilised," the astronaut said.

The astronauts were forced to return home early (GREGG NEWTON/AFP via Getty Images)

"After further evaluation, NASA determined the safest course was an early return for Crew-11 - not an emergency, but a carefully coordinated plan to be able to take advantage of advanced medical imaging not available on the space station. On Jan. 15, we splashed down off the coast of San Diego after an amazing five-and-a-half-month mission."

Fincke continued: "I am deeply grateful to my fellow Expedition 74 members — Zena Cardman, Kimiya Yui, Oleg Platonov, Chris Williams, Sergey Kud-Sverchkov, and Sergei Mikayev — as well as the entire NASA team, SpaceX, and the medical professionals at Scripps Memorial Hospital La Jolla near San Diego. Their professionalism and dedication ensured a positive outcome."

Fincke has since spoken to the Associated Press and detailed how he felt unwell while eating dinner on January 7, a day before a scheduled spacewalk.

Mike Fincke has been reflecting on his medical issue (NASA)

The four-time space flier revealed he couldn't talk, though he did not experience any pain. His crew members on the ISS were immediately concerned and requested some assistance.

"It was completely out of the blue. It was just amazingly quick," Fincke told the Associated Press. "My crewmates definitely saw that I was in distress. It was all hands on deck within just a matter of seconds."

It remains unclear what caused Fincke's dramatic medical episode with doctors having ruled out a heart attack. The NASA astronaut also said he wasn't choking, so the reason for the health worry remains a mystery.

Medical professionals have theorised it could have been down to Fincke spending 549 days in space and the weightlessness which comes with such an endeavour.