Living in Space Is Tough on Your Body

     Living in space, even just visiting for a few weeks or months, is tough. The environment out there can be deadly. Radiation will kill you slowly, and the lack of oxygen will kill you quickly. But those conditions can be mitigated. We build radiation protection into our spacecraft, and we carry oxygen, food, and water to keep us alive. But one dangerous aspect of space can’t be controlled: the lack of gravity. We currently have no effective artificial gravity.

You might have seen videos of astronauts floating and spinning in their spacecraft or sucking up blobs of water from mid-air. It may look like fun, but there are long-term consequences of living for extended periods with no gravity. 

Lack of gravity causes unexpected and sometimes bizarre changes in the human body. Astronauts who stay in space for too long develop puffy heads and bird-like, thin legs. On Earth, gravity pulls your bodily fluids down to your legs, but in space, that doesn’t occur. Your heart, for example, can more easily pump blood up to your head and away from your legs. As much as a gallon and a half more of various fluids can collect in and near an astronaut's head. Although that problem disappears rather quickly after returning to Earth’s gravity, NASA is working on ways to alleviate brain and eye strain during the time spent in space.

As their bodily fluids move toward the head of an astronaut, they can develop neuro-ocular syndrome. The optic nerve swells due to greater fluid pressure, causing the back of the eye to flatten. According to NASA, 70% of astronauts on the ISS experience some amount of swelling in the back of their eyes. This may cause blurry vision and the occasional headache. While glasses can help alleviate this, researchers are concerned about how this might affect astronauts on long-duration flights, such as a 1000-day trip to Mars.

An astronaut onboard teh ISS her eyes. Credit NASA

On Earth, your bones and muscles must constantly work to keep you upright against the pull of gravity. With a lack of gravity, that’s no longer necessary, and astronauts lose bone and muscle mass. NASA has developed exercises for astronauts to do while in space, and although the effect reverses itself once they return to Earth, doctors are again concerned about long flights to Mars.

In space, your heart doesn’t need to work so hard pumping blood “uphill” to your brain. As a result, the hearts of astronauts shrink a bit and become more spherical. Upon returning to Earth’s gravity, they can have difficulty maintaining normal blood pressure when standing. Again, this effect is reversed on Earth, but long flights to Mars may be quite problematic for returning astronauts.

As the head swells and more fluids enter the astronaut’s brain, it can shift a bit in their skull. This can lead to disorientation and issues with balance and coordination. That effect fades with time in a weightless environment.

I, for one, would be willing to deal with those issues for a chance to explore Mars, but NASA must consider the health and safety of its astronauts and is still seeking solutions to these problems.

 

Each month, I write an astronomy-related column piece for the Oklahoman newspaper. After it is published there, I post that same column to my blog page.