One of Chris Hadfield's most popular videos from aboard the International Space Station was a demonstration of what happens when you cry in space (if you haven't seen it, go check it out; we'll wait). But just as strange is what happens to your eyes when you get back from space: as many as one in five astronauts who return from the Space Station reports some vision loss when they get back to Earth, according to NASA. A new study published in the October 2013 issue of Gravitational and Space Research sheds some light on why that might be.
To investigate what happens to astronaut eyes, the investigators, from Houston Methodist Hospital and NASA Johnson Space Center, sent 18 mice for a 13-day round trip aboard the space shuttle Discovery. When they returned, the researchers examined their eyes and the surrounding tissue, and compared what they found to another population of mice who remained earthbound.
Confirming something that's already been observed in human astronauts, the researchers found that the lack of gravity actually deformed the eyes of the mice. But they also found damage that came from another source: radiation from the sun.
It turns out that Earth's atmosphere actually provides better protection from solar radiation than the metallic hull of a space ship. The mice who returned from Discovery suffered injuries to their optic nerve, and showed signs of stress in their retinas. These signs of stress returned to normal after about a week on Earth, but the damage to the optic nerve was not reversed.
The investigators point out that this research could have far-reaching implications: astronauts today rarely spend more than a few months at a time in space (Hadfield's latest mission lasted five months), but a trip to Mars or Jupiter could take a matter of years. And so far, it's not clear how their eyes will fare along the way.
Commander Chris Hadfield takes a turn in the red chair Tuesday, October 29. Make sure to tune in to CBC TV at 7 p.m. to hear all about his time in space and his return to Earth.
Via Eureka Alert