As a lifelong sci-fi geek, I used to think I’d love to hitch a ride on a ship to space, just for the sheer hell of it. After reading this, ehh, not so much.
Here’s Exactly How You’d Die in the Vacuum of Space
In the depths of interplanetary space, it’s not the unimaginable cold that kills. It’s everything else.
You did it. You annoyed your crewmates enough that they did the unthinkable: they shoved you into the airlock and kicked you out of the space station. No suit. No air. Nothing. Just you and the vacuum of space. If you want to survive this grisly scenario, you’re going to have to act quickly.
First, It’s Going To Be Colder Than You Can Imagine…
But you’re not going to have to worry about freezing to death. Yes, space is generally cold, around 3 Kelvin, due to a bath of radiation soaking the universe known as the cosmic microwave background. However, the human body is rather inefficient at getting rid of heat, especially in the vacuum of space. There are three ways to transfer heat from a warm body to its surroundings: convection, conduction, and radiation. Convection is the movement of a fluid, like warm air rising to higher altitudes. Conduction is the transfer of heat through physical contact, like when you accidentally touch a hot stove. Radiation is just that: emitting electromagnetic radiation.
Without any air or water to surround your body, there’s no way for convection or conduction to transport heat and cool you off. Instead there’s just radiation. A typical human body emits around 100 watts of infrared radiation (about the same amount of energy as an old-school incandescent light bulb). That’s not all that impressive, and it will take several hours to bring your internal body temperature below freezing.
But the coldness and the vacuum of space is going to affect you in other, faster ways. For starters, any oils or moisture on your skin will immediately evaporate in the vacuum, leaving a nasty frostbite behind in their departure. Even though you’ll be surrounded by vacuum, you won’t explode. Your skin is pretty good at keeping your insides on the inside of you, so your blood won’t boil and your eyes won’t bulge out. Instead, you’ll suffer a rare vacuum-induced malady known as ebullism (not to be confused with an embolism, which is a type of blood clot).
Ebullism occurs when the surface of your skin is exposed to vacuum (which it now unfortunately is). The lower pressure on the outside of your body causes the liquids just inside your skin to expand, causing you to swell up. Fortunately we don’t have a lot of experimental evidence that has explored the full effects of ebullism, but in some cases of accidental exposure to vacuum, people have experienced swelling of up to twice their normal size.
That’s not going to be pretty, but it is generally survivable as long as you return to a pressurized environment within a few minutes.
But you’re not going to get a few minutes.
Don’t Hold Your Breath
The moment the atmosphere escapes the airlock, you might be tempted to hold your breath to buy you more time, the same way you would when going underwater. That is an extremely bad idea. The problem is that your squishy bits (particularly your lips, throat, and upper respiratory system) are not designed to hold in a lungful of air against a vacuum. All that air in your lungs will come out, despite your best efforts, and if you try to hold it back it will escape in an especially violent and sudden way, causing irreversible damage on its way out.
Just let the air out; it’s gone.
And so, unfortunately, are YOU. Yeah, not interested, no thanks.