spaceSpace and Physics

What Would Happen To Your Body In Space Without A Spacesuit?

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Justine Alford

Guest Author

1700 What Would Happen To Your Body In Space Without A Spacesuit?
NASA Goddard Space Flight Center, "Helmet View from Astronaut Mike Fossum" Flickr. CC BY 2.0.

Have you ever wondered what might happen to your body in space without a spacesuit? Is it really as dramatic as the movies make it out to be? Would you literally EXPLODE? Could you survive? 

On Earth, we live a pretty cozy existence thanks to our protective atmosphere. It shields us from the Sun’s harmful UV rays, regulates temperatures and also maintains a nice atmospheric pressure. The vacuum of space, however, is much more hostile. Without this lovely thick atmospheric blanket, you’re exposed to all sorts of things.


The most serious dangers of exposure to outer space are a lack of oxygen and ebullism. Ebullism is the formation of bubbles in body fluids due to a reduction in ambient pressure. The pressure in the vacuum of space is so low that the boiling point of the fluids in your body decreases below the body’s normal temperature (37oC), which results in the formation of gas bubbles in your fluids that can really mess you up. You’ll swell up pretty bad, perhaps even up to twice your normal size, but you won’t explode as your skin is very stretchy. Your blood will also not boil. You will, of course, be in an immense amount of pain and your blood circulation will be impeded.

As mentioned, the other serious danger is a lack of oxygen. After around 15 seconds, your body would have used up all of the oxygen in your body and you’d lose consciousness. Some of you may be thinking “But I can hold my breath for minutes!” The situation in space is a little different than here on Earth due to the lack of outside pressure, and if you held your breath in space without a suit you’d be in a big trouble. This is because any remaining air would rapidly expand, rupturing the lungs.

After losing consciousness, you’ll probably last a couple of minutes maximum before you die. Of course, there’s all that nasty UV from the Sun which is going to give you horrific sunburn. UV and other high energy photons (X-rays and gamma radiation) would also damage the heck out of your DNA, leading to mutations that would likely cause cancer (if you survived). It’s also typically extremely cold, but you wouldn’t instantly freeze as the vacuum would cause heat to transfer away from the body very slowly.

In sum- you’d swell up, burn, mutate, pass out and your lungs might explode. Lovely. But don’t worry, if you’re ever in this sticky situation, you’ve probably got a solid minute or two to be rescued before you die, so chin up.


[Header image, "Helmet View from Astronaut Mike Fossum," from NASA Goddard Space Flight Center, via Flickr. Used in accordance with CC BY 2.0]


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