How quickly would you die in the vacuum of space? It depends on the size of the person and the situation, but the average person would probably die after a couple of minutes unprotected in the vacuum of space. When we watch movies, we often see someone lose their helmet in space and then their head explodes. This wouldn’t actually happen. If someone lost their helmet in space, they would die from lack of oxygen.
NASA has spent millions of dollars designing and building their spacesuits, but they are not actually that thick. Unlike a submarine going to the bottom of the sea, a spacesuit only has to contain the pressure of one atmosphere, or the pressure we have here at sea level on Earth. That doesn’t take a lot of the material. Most of the job of the spacesuit is actually to keep the astronaut warm or cool, depending on if they are in sunlight or not, protecting them from impacts from space junk, and keeping out solar radiation. One of the biggest problems with a spacesuit is keeping them flexible enough because they inflate with the pressure inside them. A spacesuit weighs about 130 kg on Earth, but of course that is no problem in space.
So, what would happen if you jumped out of a spaceship’s airlock without a spacesuit? Well, the first thing is that you would have to breathe out. Well, you don’t have to breathe out, but if you hold your breath you will severely damage your lungs. The pressure in space is zero and the pressure in your lungs is about one atmosphere. I say about one because it moves ever so slightly up and down depending on whether you are breathing in or out. When you breathe in, your diaphragm contracts, pulling down and lowering the pressure in the lungs, which sucks air in. When you breathe out the opposite happens. The diaphragm raises the pressure in the lungs and you breathe out. Air always moves from an area of high pressure to an area of low pressure. The second you step out of the spaceship without your spacesuit, the air in your lungs is going to expand. You can try this experiment by taking a bottle full of air on an airplane. When the plane takes off and flies higher, the air pressure in the cabin drops and your bottle will expand. This happens with your lungs. You will need to breathe out to equalize the pressure between your lungs and the vacuum of space or all of the air sacs in your lungs will rupture. If you do manage to breathe out fast enough to avoid rupturing your lungs, you will pass out from lack of oxygen in a few seconds. You obviously will not get any oxygen back if you breathe in.
The next thing that happens is your blood and bodily fluids will start to boil. That doesn’t mean that your whole body will explode and you will have probably passed out from lack of oxygen before this anyway. The boiling point of any liquid depends on the pressure around it. The boiling point of water at 1 atmosphere is 100℃, but as you reduce the pressure, the temperature required goes down. The boiling temperature of water at the top of Mount Everest is only about 70℃. Once you reach a vacuum, the boiling temperature of different liquids disappears and they boil pretty much instantly. This would happen to all of the liquid in your body and remember that we are about 70% water.
As all of the water in your body boils, it will turn to gas and you will quickly become desiccated. Something like a mummy. You would basically be freeze dried. You will also either freeze or cook, depending on where you are. If you are in direct sunlight, you will roast, although the side of you that is in shadow may freeze. If you are not near any stars, or in the shadow of something, you will gradually freeze. However, none of these things will matter because you will have died from lack of oxygen and / or ruptured lungs long before that happens. Then, once your body has desiccated, you will continue floating on the same trajectory for potentially millions of years. The only thing that would stop you would be bits of space dust that would slowly break you into pieces. And this is what I learned today.
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Sources
https://science.howstuffworks.com/question540.htm
https://www.space.com/how-long-could-you-survive-in-space-without-spacesuit
https://azeheb.com/blog/human-body-vacuum-space-really-happens
https://science.howstuffworks.com/space-suit.htm
https://www.nasa.gov/wp-content/uploads/static/history/alsj/csm21_spacesuits_pp223-228.pdf
https://www.cbsnews.com/pittsburgh/news/water-bottles-on-a-plane-and-the-pressure-hey-ray
https://physics.stackexchange.com/questions/91215/how-does-blood-saliva-boil-in-outer-space
https://www.bbc.com/future/article/20160617-why-your-blood-would-boil-in-space
Photo by Felix Mittermeier: https://www.pexels.com/photo/galaxy-1146134/