Space is a cold and lonely place. We can’t even begin to imagine how large it is either.
At any given time there is around 6-10 people in space, usually aboard the international space station. These astronauts will do regular maintenance on the station in the open vacuum of space, supported by a very strong metal cable and a highly resistant space suit. It’s safe to assume that if the cable broke and all other safety features failed you, you’d fly off into space never to be seen again. But what would happen if your actual space suit broke? Or if you just entered the vacuum of space without a suit at all? Would you explode? Would you freeze?
Well, a combination of these things and more… sort of?
If you’ve still got air in your lungs you shouldn’t keep it in there. Remember that you’re in a vacuum and that it’ll attempt to suck those oxygen molecules right out of your lungs. But lets suppose you do attempt to hold onto the limited air that you have left, you’d be fighting a losing battle that would end up with your lungs being ruptured, and the air ripped from your body. Oxygen in the rest of your body will also expand. You’ll balloon up to twice your normal size, but you won’t explode. Your skin is just elastic enough to hold you together. Because of a lack of air pressure, any exposed liquid on your body will begin to vaporise. So the surfaces of your tongue and eyes will boil. Without air in your lungs, blood will stop sending oxygen to your brain. Remember, boiling doesn’t necessary mean hot; many gasses boil at temperatures lower than 0 degrees Celsius.
You’ll pass out after about 15 seconds. 90 seconds after exposure, you’ll die from asphyxiation. It’s also very cold in space, (around -270 degrees C) so you’ll eventually freeze solid. The freezing part wouldn’t be that quick, as the lack of particles surrounding you would make it hard for the heat in your body to escape. If you were recovered from the vacuum after a minute or so, you could potentially survive. Your lungs wouldn’t be in the best shape, and you might have some brain damage, but you’d be alive nonetheless.
