An astronaut suddenly couldn't speak in space, and NASA still doesn't know why

Astronauts on the International Space Station (ISS) usually spend months at a time far from any hospital. When something goes wrong, they have to rely on flight surgeons who guide them from Earth. But earlier this year, one astronaut's sudden illness was so serious that NASA had to cut the mission short. 

And even months later, NASA astronaut Mike Fincke shared that doctors still haven't found the cause. So what actually happened up there?

Mike Fincke is a retired Air Force colonel and a four-time space flier. At 59, he was the pilot on NASA's SpaceX Crew-11 mission, which sent him to the International Space Station alongside NASA astronaut Zena Cardman, Japan Aerospace Exploration Agency astronaut Kimiya Yui, and Roscosmos cosmonaut Oleg Platonov. 

Crew-11 studied astronaut health and other science while helping keep the station running. On January 7, 2026, about 5 1⁄2 months into the mission, Fincke was eating dinner after preparing for a spacewalk planned for the next day. And all of a sudden, he couldn't talk at all. 

He felt no pain, and the episode lasted roughly 20 minutes. He has felt fine since, and nothing as it has happened before or after. "It was completely out of the blue. It was just amazingly quick," Fincke told The Associated Press in an interview.

All of the crewmates gathered around him, and they asked flight surgeons on the ground for help. "My crewmates definitely saw that I was in distress," Fincke told The Associated Press. "It was all hands on deck within just a matter of seconds."

Doctors have ruled out a heart attack, and Fincke says he wasn't choking. Beyond that, every other possibility is still open, including a link to the 549 days he has spent weightless, or floating in orbit. 

Due to this, the next day's spacewalk was canceled. If everything had gone smoothly, then it would have been Fincke's 10th, and the first for crewmate Zena Cardman. 

He and his three crewmates then landed on Earth safely on January 15, 2026, through a SpaceX flight. The mission ended more than a month early, and all four went straight to the hospital.

Since his return to Earth, he has gone through numerous tests. Fincke shared that NASA is also checking other astronauts' records for similar cases. Fincke felt bad, but his colleagues assured him, "This wasn't you. This was space, right?" and "You didn't let anybody down."

Crew-11 got home eight days after the episode, but this may not be possible on the longer lunar missions. The space agency is currently working on a lasting human presence on and around the Moon, and this includes a planned lunar base. 

In that setting, unexplained events like Fincke's may become harder to dismiss as one-off scares. For now, he says, "I've been very lucky to be super healthy. So this was very surprising for everyone." Currently, Mike Fincke works as a full-time Professor of the Practice at the Massachusetts Institute of Technology (MIT).