Photo of ISS after undocking of Space Shuttle Atlantis during STS-132

Are Humans made for Space?

The short answer is, well, no. For the last 60 years we have been struggling against gravity to put people in space. At the beginning, we sent brave men to space without any idea of what it might do to them. We knew space was an airless vacuum, but we didn’t know anything about the effects of cosmic rays or weightlessness. It was the new frontier, and we soon came to understand that, with proper protection from the vacuum of the space, short spaceflights had little to no serious effect on humans. As we have undertaken longer and longer spaceflights, we are starting to see the damaging effects space can have. From long term missions on Skylab and the International Space Station, NASA has determined that, among other things, the spine elongates, muscles atrophy, bone mass decreases, vision is impaired, the immune system weakens and red blood cell production decreases. These effects are mainly due to prolonged stays in microgravity, but what is less known is what’s happening on the genetic level.

In 2015, NASA was able to send a man named Scott Kelly to the International Space Station for one year. Kelly was the subject of several medical tests throughout his mission, as was Scott’s identical twin brother Mark, who received the same medical tests on the ground. At the conclusion of his mission, NASA was able to analyze and compare Scott’s tests to Mark’s tests. All of the data isn’t in yet, but here is what they’ve discovered so far:

Scott Kelly taking a blood sample onboard the ISS.

Telomere Lengthening:

Telomeres are the little caps on the ends of your chromosomes that help to protect them from deteriorating and are related to a number of health effects including aging. Normally, telomeres get shorter as you age, but Scott Kelly’s telomeres actually grew longer in space, only becoming shorter when he was returned to the ground. Although Scott’s increase in telomere length might be in part due to increased exercise required to maintain bone mass, scientists think another factor might be at play because the initial hypothesis was that his telomeres would actually decrease due to the increased radiation.

RNA Mutations:

Once Scott’s and Mark’s DNA had been sequenced, NASA researchers found that more than 200,000 of Scott’s RNA molecules had been expressed differently over the course of his mission. Space radiation is known to damage DNA and result in mutations, but specific cause of the change is not yet known. NASA is also investigating to see if a “space gene” is activated once astronauts go to space.

Scott Kelly sits in a Soyuz spacecraft prior to his launch in March of 2015

These two findings, although still yet vague and inconclusive, show us that there is still much to be learned about how space affects the human body. Humans have evolved for thousands of years by adapting to various environments, but the one constant was Earth. With humans reaching for the stars, we are venturing into uncharted psychological and biological territory. With pushes to venture as far as Mars, we must remember that the most complex system is not the spacecraft, but the human body. We have most of the technology to send humans to Mars, but without understanding how a trip like that would affect astronauts, we remain in the blind.

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