The Effect of Space on the Human Body

Have you ever wondered what it's like to be in space without any gravity?  What does this do to your body?  Will you change permanently?  What effect does this foreign environment specifically have on your DNA?  These are questions that will hopefully be answered after you read this post.

http://www.pbs.org/wgbh/nova/next/physics/scientists-generate-quantum-entanglement-in-space-for-the-first-time/

Life in space is pretty strange.  First of all, there is no up, down, right, left, so it is incredibly difficult to orient yourself.  Second, without gravity, you are essentially weightless.  While this is cool at first, your body is forced to adjust to this tremendous problem.  Everything that operates normally on Earth is now in a completely foreign environment.  Because of this, various physical effects can occur.

The first effect is that in space, there is no gravity to oppose the flow of blood back to your heart (venous return) and this causes a build-up of fluid in the upper body and head.  This can cause blocked sinuses, which is known as the space sniffles.  Another effect is that in space without exercise, you could lose about 12% of your bone density per year.  Additionally, you can get taller in space since there is no gravity pushing you down and the fluid filled discs between each vertebra are no longer compressed.  This stretches the spine by about 3%.  However, as soon as you return to Earth, the spine eventually compresses back to normal length.  Furthermore, muscle atrophy can occur in space because there is almost no need for muscles.

Scott and Mark Kelly, both NASA astronauts, are identical twins that allowed NASA to examine the effects of space on the genome like never before.  Since both brothers have an identical set of DNA, one brother (Scott) was sent into space for a year while the other brother (Mark) was left on Earth as a control.  After 1 year, their genetic codes would be examined to see if any significant results arose.

Which is which?

https://www.nasa.gov/feature/how-stressful-will-a-trip-to-mars-be-on-the-human-body-we-now-have-a-peek-into-what-the-nasa

NASA found that Scott Kelly's telomere length actually increased.  Telomeres are caps at the end of chromosomes that get shorter as humans age, and are thus, connected with anti-aging.  The fact that Kelly's telomeres increased was contrary to what was expected as scientists speculated that the stress of living in space would cause them to decrease.  However, once Scott returned to Earth, his telomeres quickly returned to their normal levels.  Additionally, NASA found that approximately 7% of Scott's genes experienced long term changes.  These genes correlate with the immune system, bone formation, DNA repair, hypoxia (deficiency in oxygen reaching tissues), and hypercapnia (excess carbon dioxide in the bloodstream).  Finally, space caused an increased rate of methylation (the process of turning genes on and off).  The harsh environment of space led to these differences in Scott Kelly's genes as environment affects DNA.

The full studies of the Kelly experiment have not yet been fully released, but when they come out later this year, it should give scientists a much better perspective on not just the physical effects of space, but the genetic ones, too.