Effects of Space Travel on the Human Body

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The major negative affects of space travel on the human body are most dangerous when individuals are not protected from the vacuum of space. When a person is exposed to the vacuum without a space suit, the lack of pressure and effects from radiation and temperature cause major changes in human physiology.

Due to the low pressure in space, all gases in the human body will be removed over the course of 9 to 12 seconds, a condition known as hypoxia. This results in a loss of consciousness and ultimately death in approximately two minutes. However, victims of low pressure atmospheres can be revived within about 90 seconds.

An additional problem that arises with humans in the vacuum of space is called ebullism. Because of the extreme drop in pressure, blood and other fluids in the body begin to expand, ultimately reaching twice their normal size. However, despite what is shown in the media, this does not result in the explosion of individuals as the human body is elastic enough to withstand the drop in pressure.

Although the low temperature in space will ultimately result in freezing, the fact that there are no molecules for convection or conduction, a person would die from hypoxia or ebullism first. However, exposure to solar radiation in space will cause severe sunburns in only a few seconds.

Rapid decompression also causes a major problem for the human body. A person's alveoli in the lungs generally burst, along with eardrums and sinuses. In addition, the human brain usually experiences the onset of stress-influenced shock immediately, causing the body to attempt to consume more oxygen, leading to faster hypoxia.

Above right: MIR space station. (Supplied by NASA; Public Domain; http://upload.wikimedia.org/wikipedia/commons/c/c6/Moonmir_sts91_big.jpg)

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While modern techniques are able to dispel most of the concerns of the vacuum, the affects of space travel on the human body are still apparent within a protected environment. Weightlessness is the largest influence on the human body, causing a number of problems.

Spacesickness is one of the most common side effects of space travel on the human body. Due to the fact that there is no constant source of gravity in space, individuals begin to experience unfamiliar effects. A portion of the middle ear known as the otolith is responsible for keeping a person's equilibrium constant while on Earth. In space, this organ becomes confused and stops providing the body with necessary adjustments to muscles and vision that keep people stable. Essentially, there is no real reason for muscles to contract and the brain cannot determine which way is up. Motion sickness can impact people for a number of days.

The microgravity environment of space also impacts the dispersal of fluids within a human body. In only a few minutes of exposure, the fluids in the body swell up in the upper body. This causes symptoms such as a puffy face and bulging veins. The longer the duration of space travel, the worse the effects become. Ultimately, people returning to Earth will experience problems standing and an increased chance of fainting due to the fact that plasma levels drop and a person's natural blood regulation is altered.

One of the most dramatic effects of space travel on the human body is the fact that skeletal and muscular systems lose cohesion over time. The longer a person spends in space, the less important the human skeleton and muscles become. Since these systems only exist to provide weight bearing support while in a gravitational environment, there is little need for their existence in space. According to studies conducted by the Russian Space Agency, NASA and other space agencies, muscular atrophy occurs almost immediately and bone tissue loss proceeds at a rate of 1.5 percent per month. The only way to combat these problems is through exercise and a controlled diet.

Modern developments in space suit technology and controlled environments have made the threats of the vacuum of space unlikely events. However, as humans continue to send people into space, the chances of accidents will continue. Also, studies will continue into combating the side effects of weightlessness. As humans continue the exploration of the stars, new effects of space travel on the human body will most likely be discovered.

Above left: Weightlessness. (Supplied by NASA; Public Domain; http://upload.wikimedia.org/wikipedia/commons/c/c4/Foale_ZeroG.jpg)

"Human Spaceflight and Exploration" European Space Agency: http://www.esa.int/esaHS/ESAGO90VMOC_astronauts_0.html

"Space Travel and the Effects of Weightlessness on the Human Body" Candian Space Agency: http://www.space.gc.ca/pdf/educator-microgravity_science_stu.pdf?404=1&ref=http://www.google.com/search?hl=en&client=firefox-a&hs=T6P&rls=org.mozilla%3Aen-US%3Aofficial&channel=s&q=Effects+of+Space+Travel+on+the+Human+Body&aq=f&aqi=&aql=&oq=