We have high hopes as a species when we send astronauts to space. We hope to discover new life, new stars, new solar systems, new anything! Brave astronauts risk their lives to explore the unknown.
As incredible as space can be, it poses great danger to our astronauts. There’s a risk of equipment malfunctioning, losing communication with Earth, debris storms and, who can forget, diminished vision.
We’ll admit that getting lost in space, unable to return home is a worse fate than poor vision. But for astronauts who do make it home, diminished vision is something many have to deal with.
It may seem that an article about astronauts’ vision post-space travel is less than relevant since most people aren’t astronauts. However, part of space travel is figuring out how harsh environments affect the human body (especially if some of us plan on moving to Mars once Elon Musk figures out how to accomplish that).
Human Body in Space
There has been a steady flow of human space travel since the first human spaceflight in 1961. However, it wasn’t until the early 2000s that astronauts began spending longer bouts of time in space.
Prior to 2000, astronauts were sent to space for two weeks at a time. These were quick, in-and-out operations. Today, astronauts spend six months or more in space. It has become clear that the longer a person spends in space, the more it affects the body.
Muscles are often the first thing to deteriorate in space. Because astronauts are working in zero gravity environments, their muscles don’t contract as they would on Earth.
If the muscles don’t get the exercise they need, they will weaken and pose a threat to astronauts coming back to Earth as they might have difficulty operating the spacecraft once it returns to Earth’s gravity.
Maintaining muscle mass is incredibly important in space. An astronaut has to work out at least five hours a week, doing strength training three to six times a week. Sometimes that’s not even enough for some to maintain their muscles.
Space can have numerous effects on the body because of its harsh environment. As we send astronauts to space for longer periods of time, we must learn how to counter the negative effects space travel has on the body.
Post Spaceflight Eyesight
One of those negative effects that has baffled scientists is how the eyes are affected by prolonged space travel. Unfortunately, no one knows what causes these post space travel conditions or how to fix them.
Many astronauts return to earth with different and worse vision than they had before they left. Some astronauts outgrow whatever was affecting their eyes and they revert back to normal. However, some suffer from their conditions long after their space adventure is over.
So far, it seems as if astronauts develop hyperopia (farsightedness) when they return to Earth. Once back on Earth, the eyes experience a hyperopic shift where their eyes gradually become farsighted. This is also a common side-effect of eye surgery.
What causes this shift is unknown. It is known, however, that the eyes go through a multitude of changes while in space. Though the exact cause is not known, some experts believe it has something to do with the intracranial pressure.
The increase of pressure in the cranium of an astronaut has been linked to causing changes in the eye such as:
- Retinal folds: Folds in the retina are all too common for astronauts. Retinal folds are a rare complication of retina surgery. They can result in low or poor visual acuity.
- Optic disk swelling: This swelling may cause sporadic periods of quick vision loss. For example, when standing up or doing quick movements with the head.
- Optic nerve sheath swelling: This type of swelling occurs right behind the eye. It can cause double vision.
What causes the intracranial pressure to increase in space is unknown. It is also unknown what factors would affect the pressure in a person’s head (i.e. Does exercise affect the pressure?).
Some experts suggest that the eye is remodelled after being in space for such a long time in an attempt to adapt to the new environment. That way, when the astronaut returns to Earth, the eyes get quite a shock as the intracranial pressure goes back to normal.
Why do the eyes not go back to normal too? That’s an excellent question, and the exact question that all scientists are asking.
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Mars on Hold
We’re living in a time that would officially be categorized as a science fiction movie. We carry around little computers in our pockets, we can video chat, we can 3-D print organs, and we send people to space relatively confident that they’ll return in one piece.
OK, so maybe we live in the prequel to a science fiction movie where humans are still trying to figure things out, but we’ll get there.
“There”, in our case, happens to be Mars. Just as it was once humankind’s dream to reach the moon, it has now become Mars. Setting up on Mars is NASA’s priority.
This sandy and sometimes unpredictable planet is thought to be able to sustain human life due to evidence that water lives (or used to live) just below the surface.
However, in our quest to find if Mars could support humans, we’ve seemed to have overlooked the fact that we may not be able to support Mars. This is especially true if in the long run, eyes deteriorate as we spend more time in space.
Solving astronauts’ eye problems should be on the top of the priority list for experts because without a solution, our mission to Mars will be impossible. Until we are absolutely certain of the causes of vision impairments in space and how to fix them, interplanetary travel would be too dangerous to accomplish.
At its furthest, Mars is 249 million miles away from Earth. It takes 14 minutes for a message to send from Mars to Earth and takes six months to travel there (provided Mars is at its closest point to Earth).
A space station would be highly visual, not only to operate machinery but to survive on a foreign planet that has not been made accessible to the visually impaired. If a crew were to lose their vision on Mars during a mission, the chance of survival would be slim.
Space travel is exciting and futuristic, but it isn’t anything like the movies. There are so many little details to account for before we head to Mars.
Figuring out why astronauts’ vision suffers after prolonged spaceflights is one detail that can’t be overlooked or ignored. Without our vision, we won’t be able to master space travel.
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