Science Fiction Problems: The Vacuum of Space (Don’t hold your breath)

I could survive for 1 minute and 41 seconds in the vacuum of space
Of course at that point you'd be a vegatable...

I was trudging around the internet when I discovered a very interesting article written by Nebula and Hugo award-winning science fiction writer (among a great many other accolades) Geoffrey Landis. The article explains the issue of explosive decompression (the instant or very rapid removal of atmosphere, in this case from a plane or spaceship cabin), the effects of a vacuum on the human body, and all the myths and misunderstandings thereof. I was so intrigued by the wild disparity between common assumptions and hard science on this topic that I saw fit to condense this very well-referenced but otherwise fairly inaccessible article into a happy little summary, for the benefit of our readers. Be sure to check out the articles for more details if you can stomach the science-speak (Landis is a Doctor of Physics) and definitely take a look at his website, especially his books if you like hard science fiction.

The Hazards of The Black


firefly river in a space suit
Firefly addressed this problem well


As I assume most (hopefully all) of you know, there is no air in space. There are trace particles, but beyond the atmosphere of our planet, only a void exists, lacking any breathable air. Lack of air not only means no breathing, but also exerts an ambient force, like a vacuum cleaner pulling in all directions. Science Fiction movies and books have used the threat of unprotected exposure to open space for decades, but most rely on rumors and uneducated guesses as to what actually happens when someone gets shoved out an airlock without a space suit.

You can survive exposure to space (for a little while)

Apparently it is possible (assuming you don’t hold your breath) to remain conscious in a complete vacuum for 9 to 12 seconds, and alive for a short time after until you die of Hypoxia, better known as oxygen deprivation. Landis cites several examples of human exposure to extremely low and null-atmosphere decompression where not only do the victims survive, but fully and rapidly recover. One technician was accidentally exposed to almost null decompression, lost consciousness after about 12 seconds, and was rescued after almost 30 seconds when the pressure was finally restored. He fully recovered later.

R2D2 vacuum and Leia
Not that kind of space vacuum...

This is not to say that you cannot die instantly from exposure to a vacuum- if one were to hold their breath, for example, thanks to the extreme difference of air pressure, the lungs would explode, killing the victim instantly by sending large pockets of air to his heart and brain. The article also points out that several animals subjected to decompression suffered immediate heart attacks that killed them on the spot due to the shock. The point is, there is nothing about a lack of atmosphere that means immediate death in every case- as long as you don’t hold your breath.

You will not freeze and/or your blood will not boil

This has been flubbed in lots of movies, but each case simply doesn’t agree with the facts. There is an arguement that due to the lack of air pressure, the boiling point of blood in the human body is lowered enough that if a person was exposed to open space without protection, his blood would actually boil at its normal temperature of 98.6 degrees. This would do all kinds of nasty things biologically which would ensure a painful death, but realistically (as Landis explains), the boiling point would not be lowered enough to cause this traumatic effect.

Similarly, according to Landis, space is not actually cold. Temperature is measured based on air pressure, and so without an atmosphere, space cannot actually be cold, or hot for that matter. Space, as a vacuum, is actually an excellent insulator (think thermoses), so there is nothing about it that would freeze a human body solid as soon as it exits the ship without a space suit. Liquids would freeze at higher temperatures, forming ice in space due to the lack of air pressure, but solids remain stable.

There are plenty of other examples of the realities of vacuum exposure in this article (not to mention the time-tested favorite, explosive decompression), so be sure to check out the link above. It is my sincere hope that anyone reading this, having been enlightened by this important insight, will not make the same mistake that so many cheesy science fiction movies have in their own stories.

12 thoughts on “Science Fiction Problems: The Vacuum of Space (Don’t hold your breath)

  1. Wait a minute…there’s no oxygen in space? Then how did those astroid worms in Star Wars stay alive, I mean we all know there are spaceship eating astroid worms out there. And what about all the cartoons with the convertable, or open topped spaceships, you can’t tell me that the Jetsons was lying to us…that can’t be true. No, no, there must be oxygen in space, I’m sorry that you have been so deceived by this ostensible man of science.

    1. Don’t worry Kyle, giant asteroid-dwelling space worms are not entirely in conflict with science (although they always made me wonder what on earth they can find out there to eat other than the occasional spaceship). If the worm wasn’t reliant on respiration (i.e. perhaps it consumes the asteroid for oxygen and hydrogen) then it wouldn’t need air, and that would take care of the most immediate problem.

      It’s ok, the mean old scientist can’t take away your giant worms if you believe hard enough.

      1. Actually, in Star Wars mythos, the space worms created their own internal atmosphere and ecosystem and often had other creature living inside them (hence the Mynocks which attach the Falcon).

  2. What I always wondered was how the pistols in Heinlein’s Rocket Ship Galileo fired on the moon when there was no oxygen for the gunpowder in the shells to unite with.

    Avoiding mistakes in contemporary scifi?

    Don’t hold your breath. (Ahem.)

    1. That’s actually not so difficult to explain away, Dr. Williams. There are several explosives that don’t require oxygen to react, it’s a simple matter for a Science Fiction to have replaced gunpowder with something that can function in space, or otherwise come up with some clever way of containing small gas pockets in each cartridge, or even the needed gases in solid form.

      1. There is also air contained inside the cartridge. It is not packed full of powder ( if it was the pressure would be too high and damage/ destroy the gun) as some people expect. So this air in there, which is heated when the powder burns (that’s right smokeless powder does not explode it burns, take a shotgun shell apart some time and check) and forms the pressure that propels the bullet. The real question is if the primer would go off in space?

      2. Ah, you’re right about that- however, the effect of the gunpowder burning is an explosion of expanding air behind the bullet, which is what propels it to velocity. I don’t think that there is enough air within the cartridge to create enough expansion for this- although as far as I know it hasn’t been tested. I suppose you could simply calculate it, but there are more factors involved than the volume of gas, as in what you pointed out, whether the primer would fire. Personally, I’m a fan of electronically-fired caseless ammunition, which typically use a variation of moldable solid explosive material that would at least ignite in a vacuum, even if there’s still the problem of having gas to expand behind the bullet.

    1. That was the goal, Stephanie. I’m glad you enjoyed it. If you take a look at the article I linked, there’s a lot more information there that I didn’t cover, like explosive decompression and the exact effects it has on the human body. Apparently it gives you gas.

      Some might prefer the idea of instant freezing or any of the other science fiction renderings, but personally I am intrigued by the idea that you can survive reasonably well in space as long as you have oxygen. Of course there’s radiation and tons of other hazards to deal with, but I can see someone writing a neat story based on these ideas.

  3. Yes, but Heinlein never provides any of that necessary supporting detail–the guns just magically fire!

    Aside from that, I loved the book.

    And then there are all the planets in Star Trek that are completely lifeless and yet have a breathable atmosphere. And the new species that evolve right before your eyes. And the elimination of poverty on earth (when human nature clearly hasn’t changed because you still have the villains necessary for conflict and plot). No problem with warp drive or transporter technology, but those other things wreak havoc with my suspension of disbelief. Yet I love Trek–but there are certain episodes that test my loyalty because their writers didn’t read Erik’s post!

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