So far 15 NASA astronauts have reported significant vision damage after long trips to space, and it's been an unsolved mystery.
But now, vocativ.com reports, scientists think they have figured it out. This is a good thing, because as we start to contemplate trips to Mars, we don't want our astronauts to have to sacrifice their eyesight.
It all comes down to the movement of fluid in our bodies. While we're upright during the day, fluid is naturally pulled down toward the feet, but when we lie down during sleep it’s concentrated in the head, building up pressure behind the eyes.
That’s OK, because we only sleep for about a third of the day; but zero gravity is equivalent to constantly lying down, resulting in constant pressure. Over time that can distort the shape of the eye, and some astronauts on the International Space Station have already felt the effects.
The problem, it turns out, comes from the disruption of the day-night pressure cycle. To figure it out,
researchers recruited eight cancer survivors who had a device called an Ommaya reservoir implanted in their head as part of their chemotherapy, and that made it possible to measure tiny changes in the pressure behind their eyes in zero gravity.
Read the full story: