NASA astronaut Michael Fincke revealed that doctors still don't know what caused his sudden inability to speak during a January mission aboard the International Space Station. The medical episode prompted an unusual evacuation back to Earth, marking the first time in the station's 25-year history that astronauts returned early due to a health issue.

Fincke, part of Crew-11 alongside astronauts from NASA, JAXA, and Roscosmos, experienced the incident while eating dinner on January 7. He described the onset as "completely out of the blue" with no pain, though his crewmates quickly recognized something was wrong. Testing ruled out a heart attack or stroke, and Fincke suggested the condition was "space-related."

Originally scheduled to complete a 167-day mission in February, the crew returned early, splashing down in the Pacific Ocean on January 15. All four astronauts were taken to a hospital for evaluation, partly to protect the privacy of the affected crew member. Fincke expressed disappointment about cutting the mission short, telling CBS News he felt he had "let my friends down" despite NASA officials jokingly telling him to stop apologizing.