An astronaut fears he’s grown so much while in space he might not be able to fit into his transport back to Earth.
Norishige Kanai, from Japan, claim he’s grown nine centimetres during his three weeks at the International Space Station.
He has taken to Twitter to express concern he won’t fit in the Russian Soyuz vehicle set to take him home in June.
NASA scientists say astronauts can grow up to three percent taller while in space or around five centimetres for someone 1.8 metres high.
Studies have shown that when the spine is not exposed to the pull of Earth’s gravity, vertebra can relax and expand.
Kanai wrote on Twitter: “Good morning, everybody. Today, I have a major announcement. I’ve had physical measurements since I got to space, and, wow, I’ve grown by up to nine centimetres.
"I grew like a plant in just three weeks. I haven’t grown like this since high school. I'm a bit worried whether I'll fit in the Soyuz seat when I go back."
Update: Kanai later apologised for his tweet, saying he had grown 2cm and not 9cm as he initially claimed.