A Japanese astronaut who has been living on the International Space Station for three weeks says he has grown 9cm since he arrived.
Norishige Kanai told his followers on Twitter that he is now worried he might not fit into the seat of the Russian Soyuz vehicle that is due to bring him home in June.
Mr Kanai tweeted: "Good morning, everybody. I have a major announcement today. We had our bodies measured after reaching space, and wow, wow, wow, I had actually grown by as much as 9cm!
"I grew like some plant in just three weeks. Nothing like this since high school."
NASA says astronauts can grow an average of 2cm-5cm in space because there is less gravity pushing down on their vertebrae in the back so the spine can elongate.
Mr Kanai, who is 41, trained as a medical doctor and was selected as an astronaut candidate by the Japan Aerospace Exploration Agency in 2009.
He joined five other international astronauts in December for Expedition 54 to the International Space Station and is orbiting Earth 250 miles above.
