What Happens to Your Body in Space?

  • Kelly Shen ’23

Image from Unsplash.com

The 2019 Twin Study, conducted on the ISS, provided us data on how the body changes in space. Astronaut Scott Kelly spent 340 days in space while his identical twin Mark stayed on Earth. The results of NASA’s findings were recently published, and scientists have identified a number of molecular changes that occur in space, detailed below. 

Telomere lengths

Telomeres are structures at the end of each chromosome, their job is to protect the chromosome from deterioration or fusion with other chromosomes. During the study, Scott’s telomeres lengthened while he was in space and went back to normal once he was back on Earth. The culprit is space radiation. Though astronauts are mostly protected from harmful radiation, there was still evidence that it affected the astronauts’ DNA. This led to chronic oxidative stress, which is caused by an imbalance between production and accumulation of oxygen reactive species (highly reactive chemical molecules formed due to the electron acceptability of O2) in cells and tissues. Thus, Scott’s telomeres ended up being shorter than when he first flew into space. 

Mitochondria: powerhouse of the cell

Mitochondria play a big role in the human body, and when it’s not working properly that leads to a cascade of problems. Health issues like muscle and bone loss, heart and liver problems and immune system dysfunction were identified in the astronauts, and now we know it’s because of an issue called mitochondrial dysfunction. When in space, changes in gravity and cosmic radiation cause the mitochondria to be suppressed, and that is the root cause of disruptions in the circadian rhythm and in other body parts like the ones mentioned above. Fortunately, there are drugs for mitochondrial disorders, so the next step would be to test those in space.

Heart Stress:

A study done on fruit flies that were living in space showed that their hearts were smaller and less efficient at pumping blood. The same might happen in humans if we spend extended periods of time on the moon or on Mars. The research done on fruit flies showed that instead of contracting like normal heart muscles, the weakened heart muscles pressed down instead, which could cause some potential problems in humans should that happen to us. Microgravity makes the heart change its shape from an oval (like a water-filled balloon) to a round ball (an air filled balloon), and space causes atrophy (progressive degeneration or shrinkage of muscle or nerve tissue). The muscles in the heart are needed to constrict the blood vessels, so they cannot control blood flow as well if altered in space.

Here is a link that I used for research in writing this article, it leads to a page about cardiovascular health in space from NASA’s website. Feel free to check it out if you want to learn more about space experiments!

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