Microgravity Made an ISS Astronaut Grow 3.5 Inches Taller
Japanese astronaut Norishige Kanai has a big problem. After just three weeks in a microgravity environment aboard the International Space Station, Kanai has seen a phenomenal change in his body's physiology, as he's managed to grow an impressive 3.5 inches (9cm) in height.
Certainly, many of us would love the opportunity to grow a little taller, so the thought of enjoying a natural stretch might be initially appealing. In a statement, though, Kanai has expressed concern about whether or not this could affect his chances of getting home in one piece.
According to Kanai, he's no longer certain he can fit inside the chair of the spacecraft that's taking him home:
Kanai probably doesn't have much to worry about. While the three inches he's gained have put him at around six feet tall, the Russian Soyuz TMA Descent Module is designed to fit astronauts of up to six foot three inches, meaning that Kanai still has a little more growing room before he'd struggle to fit.
That said, considering that he's grown an average of over an inch per week thus far in space, it's not entirely impossible that this growth might continue. Kanai had better think short thoughts and spend some time pushing his head against the ISS walls to try and squash himself back down a bit.
There are all sorts of fascinating changes that occur in the human body as a result of an extended period of weightlessness. Perhaps the most appealing is the possibility of this kind of growth, which in truth isn't actually the case of a person adding new mass, but rather, of bones in the spine spreading out when they're no longer being weighed down by gravity.
Many astronauts gain a little extra height while above the planet, but it's also common for them to shrink back again once they're back on solid ground. Kanai likely simply has a particularly dense spine normally, meaning that he's got more of himself to stretch out now that he's not suffering from the crushing weight of gravity.
This is one of the nicer effects of zero gravity on the body; astronauts have also been known to experience eye strain and headaches, likely because their brains are floating within their skulls and stretching out their optic nerves. It's also common for this process to lead to a lessening of brain fluid around an astronaut's skull, as their brains float around, disturbing cushioning liquids that would otherwise be stationary.
Then, there's the real bugbear of space travel: the danger of muscle loss. Without gravity to weigh the body down, every action in space, from lifting objects to simple breathing, takes less effort. Muscles can waste away in space without careful, extensive exercise, and this can mean that astronauts return to Earth in a severely weakened state.
At the end of the day, humans are biologically designed to thrive in the environments that are most common on Earth - and that means evolutionary quirks that specifically take advantage of our planet's gravitational pull. That said, humans aren't really designed to live in extreme conditions found on Earth either, such as below freezing temperatures or extreme desert heat - in spite of this, plenty of people live in Dubai and Yakutsk.
Our species has a habit of forcing our environments to suit our needs while enduring otherwise deadly conditions. No doubt over time, we'll find better ways to counter the negative effects of space travel.