Houston, we can't see shit! - Astronauts and their far-sight...
Why do astronauts come back from space with bad vision? The little problem about travelling to mars that we didn't see coming.
Space, the final frontier. These are the voyages of the Starship Enterprise. Its continuing mission to explore strange new worlds, to seek out new life and new civilization, to boldly go where no one has gone before… but, first, we need to check with an ophthalmologist. Because we can't see a thing!
Of course, Geordi couldn't know that... Source
It does sound weird as intro of a series, but it is closer to reality, unless we first solve some issues here at Earth. It looks like before jumping into exploring the universe, we need to take care of some minor hardware issues that have little to do with interplanetary ships or martian colonies, they've to do with our eyes. Because, it turns out that, the longer time someone spends in space, the worse he/she sees in close range. And it is kinda wicked to even consider a pilot that can't see the controls attempting to land a huge ship... Isn't it?
The thing with space and eyesight is something like this: The longer the space trip, the more changes in the flow of liquid around the brain, this alters the fundus of the eye, therefore, near sight.
When beams of light focus right at the retina we see perfectly, full HD, beautiful and perfect, yet we all know (as computer users) that this is not always like it is supposed to be. Myopia.
When the beams of light, do not converge at the retina, but a little bit further back, we also see out of focus: This is what we call hypertrophy.
Usually, we have the ability to see close and far, we are able to modify that focal point by deforming the shape of that intraocular lens: the crystallin. As we grow up, contrary to the natural phenomena other parts of our body suffer, the crystallin gets larger and stiffer, it becomes harder to change its shape. Consequently, it "freezes" in the far sight mode, and has problems focusing near things. This is called presbyopia.
For us to perceive an image from what the eyes sense, we obviously need a brain-eye connection. This role is played by the optic nerve; that, unlike the rest of the nerves in the human body, behaves like a miniature part of the brain sticking out of the inner side of our cranial cavity, towards the sockets where our eyes dwell: The Orbit. Everything is packed up by some membranes called meninges and a transparent liquid our brain floats in: Cerebrospinal fluid (CSF).
As all living things we know, this whole system I described in the previous paragraphs developed and evolved under the conditions our beloved planet Earth offered. Now, what happens when we send this gooey, sophisticated system to the stratosphere?
For some strange, unknown, reason we have to still discover; in space, the CSF is not reabsorbed at the usual rate and starts accumulating. As we all know, it is not good for the human body to stockpile stuff somewhere it is not supposed to be.
The skull becomes a sealed container that progressively increases its internal pressure.
This raising pressure is transmitted through the optic nerve to the eye, triggering a series of anatomic changes that translate into dysfunctions. Think about it this way: Pressure rises, pushes the eyes out from the inside, the eye gets "shorter" and the light beams focus as if the subject had hypertrophy.
Ok, calm down, skywalker... We've already solved this at Earth with a pair of good old glasses. As a matter of fact, this is what NASA does: They give glasses to the astronauts beforehand, so that they may use them as they spend more time in space.
Astronaut Doug Wheelock wearing an EMU spacesuit and glasses - Source: quora.com
Yet, the problem does not end there, because pressure keeps building up, and this can lead into irreversible consequences. One of the, having your head under constant pressure is not cool and renders into changes of the brain parenchyma (I've waited SO LONG for a moment to use that word!). The eye and optic nerve in particular are conformed by tissue that is metabolically very active, something that translates in biologic economics as: They need a lot of oxygen and nutrients that are delivered by blood flowing. Blood arrives there bombed by the heart that gives it enough pressure to do the trip. If the factors are alteres, the intracranial pressure may overwhelm the blood pressure... blood would not irrigate that tissue and cells would die, leading into permanent sight loss.
Ischemia.
Ischemia is "something is not getting the blood it needs to work properly, it is bloodthirsty", but closer to a heart attack than to Dracula. Ischemia is what some Steemian's brains have.
Ok, good to know. But I wasn't thinking on going to Mars this season... So I don't care.
OK, cool, perhaps you'll not go this summer, or the next. Perhaps we'll never take a trip to Mars (or any other space location) for vacations. But space exploration is taking HUGE steps in this latest years, and our sons and daughters may do so! It won't be long until we send people to Mars, it takes only one thousand days to do the two way trip. One thousand days of increased pressure, of pushed eyes. One thousand days where no rubber band simulating gravity can help us, because it is not a muscular problem: It's an hydraulics problem. It is part of our nature as creatures adapted to Earth's gravity. A part of nature that we never took into consideration until now, that we have the urge to take a trip outside home, or at least enlarge our territory into lands where the gravity levels are different.
The thing is that, to better understand how extraterrestrial conditions can affect us, se need data, to get data we need experiments. To perform those experiments, we need controlled environments and specific test subjects (even control groups!). Something like grabbing a couple of twins, send one to space while the other stays grounded... Something impossible! Except that it was just done.
Scott Kelly, the space twin, spent a year at the ISS, while Mark, the lesser one, trimmed his mustache, watered his brother's garden and fed his dog. (Source above the image)... Obviously, NASA.
This particular case is being used to study the long term effects of space dwelling compared to Earth dwelling.
If we wish to explore and understand worlds beyond ours, we need to be aware that time is gold and that there's plenty of issues that need a solution; problems that we've just started to detect. If we wish that Matt Damon living happily ever after with his potato field in mars... "we are going to have to science the shit out of this".
At least, that's how I see it.
lol