On Tuesday, the spaceflight world twittered in amazement after a Japanese astronaut posted about his surprising growth spurt on Twitter. "I have a major announcement today," Norishige Kanai wrote. "We had our bodies measured after reaching space, and wow, I had actually grown by as much as 9cm!"
He had grown so much after just three weeks, the astronaut said, that he was concerned about fitting into his cramped Soyuz spacecraft seat for the ride back to Earth later this year. Each astronaut is measured for his or her seat in the tiny spacecraft used to ferry humans to and from the International Space Station. Some former NASA astronauts able to fly on the space shuttle, including Scott Parazynski at 6'4", were denied stints on the station because they were too tall to fly in the Soyuz.
Elongation in outer space is normal, as the spine spreads out in microgravity. Typically, astronauts grow by about 2 to 5cm during a six-month stay aboard the space station, and then return to a normal height within a day or two of coming back to Earth's gravity.