The Effects of Space on the Human Body

Ryan Sebastian, Site Manager


Space is the final frontier and with all the science fiction shows and movies in the previous 5 years like Star Trek, the Expanse, The Martian, Star Wars, Farscape and many more, it seems the draw to going to Mars and the far reaches of the galaxy has increased.  Recently we saw the first manned flight to the space station from the U.S. since 2011, and the first time that the shuttle was made by a private company.   The next goal for many space programs is the journey to Mars, but here at Synergy, we want to know: what happens to the human body when in space for long periods of time?

Even for the shorter amounts of time in the International Space Station (ISS) there are a lot of adversities that the human body endures which brings along side effects that can have both short-term and long-term consequences.  Some of the major side effects involve bone density, radiation, cardiovascular health, immune system, and even eye sight.

With the lack of gravity in space, the body does not encounter as much external load that promotes bone density and strength. Whereas on Earth, bone density decreases at a rate of 1-1.5% per year later in life as a natural progression, in space bone density decreases at a rate of 1% per MONTH (Perez, 2016).   To help combat this astonishing rate of loss, astronauts go through rigorous amounts of daily exercise and are monitored closely by their teams back on Earth’s soil.  This exercise regimen helps with multiple aspects including bone density, muscle strength, mental health, and cardiovascular health.

Since there is a lack of gravity, fluid tends to stay more towards the head, which causes a few problems.  The decrease in blood flow to the cardiovascular system can cause vision problems, and the shift of fluids causes the kidneys to struggle with dehydration and bones to excrete more calcium than normal. To help with this problem, astronauts wear compression cuffs on their thighs, and constantly perform various tests to check the levels and functions of each individual.

In space humans are exposed to more radiation that what we encounter here on Earth due to its magnetic field.  When astronauts are in the space station, they experience ten times the radiation that we experience on Earth even though they are located in low orbit.  Once further into space, astronauts would experience even more harmful radiation.  Another phenomenon the astronauts experience is changes to their immune system.  Because of the confined space and lack of gravity, microorganisms that live on everyone’s body can easily transfer which can increase illness.  Add in the increased stress hormones there is an increased susceptibility to illness which makes nutrition and exercise required to stay healthy.

With all the adversity that space creates for humans there are still constants to what we know on Earth.  Nutrition and exercise is key whether you are here on Earth or in space.  Keeping muscle mass and bone density relies on exercise to create impact stimulating growth.  Nutrition aids in keeping illness away and even helping with problems caused by radiation.

There are still more advances that are needed to allow for a safe three-year journey to Mars, but studying the effects that the astronauts experience on the space station brings us a little closer.   Hopefully soon science will allow us to experience the final frontier.



Perez, J. (2016, March 30). The Human Body in Space. Retrieved August 19, 2020, from