Japanese Astronaut Concerned After Growing 3.5 Inches Taller in Three Weeks [Update: He Was Wrong]

Norishige Kanai. (Image: NASA)

Update: January 10, 8:20 am EDT: According to new reports, Kanai either fabricated this story, “mis-measured” himself, or it was all a joke that didn’t translate well to English. In a tweet posted earlier today, the Japanese astronaut apologized, claiming he had measured his height after the ISS captain questioned the apparent growth, and he had grown 2 cm, which is just three-quarters of an inch—a far cry from the 3.5 inches claimed a day earlier. “This mis-measurement appears to have become a serious topic, so I must apologize for this terrible fake news,” he tweeted. And he never explained how the original mistake occurred. “I am a little relieved to be able to ride on the return Soyuz,” Kanai added.

Sounds like an honest mistake; it’s doubtful an ISS astronaut like Kanai would willingly spew false information. Fair to say, however, that he needs to be careful next time he tweets something so extraordinary.


Below you’ll find our original post, “fake news” and all.

Microgravity environments do strange and often undesirable things to the human body, such as weakening muscles and bones, shrinking hearts, and flattening eyeballs. But it’s also known to make astronauts a bit taller, as Norishige Kanai is now learning. The Japanese astronaut arrived at the ISS just three weeks ago and he’s already grown an astonishing 3.5 inches (9 cm)—and he’s now worried that he won’t fit into the seat of the Russian Soyuz return vehicle.

“Good morning, good morning,” tweeted Kanai earlier today from the International Space Station. “Today there is a serious report... I had physical measurements since I got to space... [with] heights up to 9 centimeters! I grew like some plant in just three weeks, nothing like this since I was a junior high school student. I am a bit worried whether my body will fit in the return Soyuz seat.”

Along with astronauts Scott Tingle and Anton Shkaplerov, Kanai arrived at the ISS on December 17, 2017 after launching from the Baikonur Cosmodrome in Kazakhstan.


Astronauts grow an average of between two and five centimeters in space, or about 3 percent taller than their usual height. Astronauts get taller in space because the absence of gravity allows the vertebrae in their spines to spread apart. Nine centimeters, or 3.5 inches, is a lot, but as Libby Jackson of the UK Space Agency told BBC, “it is possible, knowing that every human body is different.”

Image: NASA

Kanai is scheduled to return to Earth in April. As to whether or not he’ll fit into the seat of the Soyuz return vehicle, he’s probably going to be just fine. According to NASA, the Russian Soyuz TMA descent module can accommodate astronauts as tall as 6 feet 3 inches (190 cm). In today’s tweet, Kanai said he’s now just shy of 6 feet (182 cm). He’d have to grow more than another 3 inches, or 9 cm, for his height to become a problem. That doesn’t seem likely, but given that he grew so much in just three weeks, who knows?

But it’s a good thing the crew isn’t using the old Soyuz descent capsule, the one used from 1986 to 2002—a module that was only able to accommodate astronauts with a maximum height of 6 feet.



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George Dvorsky

George is a senior staff reporter at Gizmodo.