NASA astronaut Mike Fincke has provided details about the mysterious medical episode that prompted the space agency's first medical evacuation from the International Space Station earlier this year.

Fincke, a 59-year-old retired Air Force colonel and four-time space flier, said the incident occurred on January 7 while he was eating dinner after preparing for a spacewalk scheduled for the following day. He suddenly lost the ability to speak and was in visible distress, though he experienced no pain during the episode.

The astronaut's crewmates immediately recognized he was in distress and contacted flight surgeons on Earth for assistance. The episode lasted approximately 20 minutes, after which Fincke said he felt normal. He described the onset as happening "like a very, very fast lightning bolt" and said it was "completely out of the blue."

Doctors have ruled out a heart attack and Fincke confirmed he was not choking, but the cause remains unknown despite extensive testing since his return to Earth. Medical professionals are considering whether the episode could be related to his 549 cumulative days in weightlessness across multiple missions. NASA is reviewing other astronauts' medical records for similar incidents.

The medical emergency resulted in the cancellation of a planned spacewalk and the early return of Fincke's crew aboard a SpaceX capsule on January 15, more than a month ahead of schedule. The crew was taken directly to a hospital upon landing near San Diego.

Fincke identified himself as the affected astronaut in late March to end public speculation about the incident. He said he cannot provide additional medical details to protect the privacy of future astronauts who might face health issues in space. Despite the setback, Fincke expressed hope that he might return to space in the future.