Science, Fiction, Life

Can Life Really Survive in Space?

A zerg swarm, silhouetted against some colorful nebulae as they cross the vacuum of space.

In Starcraft, the biological, hive-minded Zerg can survive and even thrive in the vacuum of space, while the more fragile humans (and presumably the Protoss) require some sort of space suit. So that got me wondering: How plausible is it for living organisms to be able to withstand the vacuum, extreme temperatures and high radiation levels of space?

Fist of all, I’m going to set aside how the Zerg fly around in space. That may be the subject of a future post. I’m more concerned with just the idea of a hydralisk standing on an exposed moon-like surface and not immediately freezing or suffocating or otherwise dying gruesomely.

As you may imagine, NASA is quite interested in how living things react to space-like conditions. Between concerns over contaminating places like Mars and Europa with terrestrial microbes, and that whole “launching humans into space” business, there have actually been a lot of studies done on the topic.

Before we dive into more extreme forms of life, let’s examine what happens to a human exposed to vacuum. I want to clear up one misconception right away: You don’t pop like a balloon in space. Nor do you instantly freeze solid or pass out. It turns out that your circulatory system provides enough pressure so your blood wouldn’t boil even in zero pressure, and you remain conscious as long as the oxygen that’s already in your blood lasts (about 15 seconds). The biggest danger is holding your breath: don’t do it!

Even though humans don't instantly die in space, it still is deadly. That's why so much work goes into designing good space suits for astronauts.

When exposed to vacuum, all the air in a person’s lungs goes rushing out in a vain attempt to fill the void. This can cause serious damage if you try to hold it in, in much the same way that a scuba diver who inhales pressurized air at depth risks fatal lung damage if she holds her breath and then swims to the surface.

You don’t instantly freeze in space because there is no effective way to lose heat! Normally we’re surrounded by air which can convect heat away, but in space the human body is not in contact with other matter, so the only way it can lose heat is by radiating it away as infrared light, which is a very inefficient process. Anyone who has ever used a thermos to keep their coffee warm knows that heat doesn’t transfer through a vacuum very well!

Of course, people still have issues when exposed to space. You can get a nasty sunburn in seconds. You can get the “bends” (another affliction of SCUBA divers, in which bubbles begin to form in the bloodstream and cause damage). There will be tissue damage. Hence the bulky space suits that NASA uses and the bulky space marine suits in Starcraft.

But the point is that even fragile creatures like humans can survive for a few tens of seconds in a pinch. But we want to talk about the Zerg: insect-like creatures that can survive intense radiation and the vacuum of space with little to no damage! How plausible could that be?

Well, let me introduce you to the tardigrade, an insect-like creature that can survive intense radiation and the vacuum of space with little to no damage! Tardigrades, also known as “water bears” are microscopic, water-dwelling, segmented and absurdly durable creatures. They are especially hardy when they are in a state of suspended animation.

Tardigrades (a.k.a. "water bears") - distant relatives of the Zerg?

According to Wikipedia:

Some can survive temperatures of -273°C (-460 °F), close to absolute zero, temperatures as high as 151 °C (303 °F), 1,000 times more radiation than other animals, and almost a decade without water. In September 2007, tardigrades were taken into low Earth orbit on the FOTON-M3 mission and for 10 days were exposed to the vacuum of space. After they were returned to Earth, it was discovered that many of them survived and laid eggs that hatched normally, making these the only animals known to be able to survive the vacuum of space.

There are also plenty of simpler creatures that can survive in extreme conditions. For example, the bacterium deinococcus radiodurans can repair its DNA on the fly, withstanding doses thousands of times higher than the lethal limit for humans. For the zerg to survive long in space, they would need to share this ability to repair radiation damage rapidly.

They would also have to be able to survive without air, and to completely exhale all the air inside them safely before entering space. One possible mechanism to help the zerg survive without air is the creep. Creep provides sustenance to zerg buildings, but if it also could nourish zerg creatures, it might keep them going without the need to breathe. Combine that with a slow metabolism, making any nourishment or oxygen absorbed from the creep last for a while after they leave it, and you might be able to do away with the need to breathe. This is admittedly far-fetched, and would work much better for microscopic creatures with higher surface area to volume ratios.

The problem with a slow metabolism is that extreme temperatures would be problematic. Although an organism doesn’t freeze or burn instantly in space, long-term exposure would still be deadly unless the organism is able to moderate its temperature by matching its metabolism to the amount of energy going in and out while it sits in space. Did you ever wonder why space suits are white? It’s to reflect sunlight! Humans already put off a lot of heat, and it’s already difficult to get rid of it in space, so NASA doesn’t want even more heat from the sun making things too toasty for the astronauts. I’m not sure I have a good way around this for the zerg. Take a look at any zerg swarm and they look pretty active, but that means a high metabolism, producing excess heat that needs to be dealt with and requiring extra calories and, presumably, oxygen which would be difficult to get in space.

Pressure is, in my mind, less of a problem. We know that the zerg have an armored carapace, and since even fragile human tissues can provide enough confining pressure to keep the fluids inside from boiling, I’m willing to believe that the Zerg could survive extreme low pressures.

This hydralisk seems perfectly happy in space. Just look at that big grin!

The question of course, is how the Zerg could evolve in space? But luckily, we can wave our magic wand to explain this point. We’re told in the games that the zerg did not really evolve independently but were engineered by the ancient and powerful Xel’naga, combining many different species. Considering that present-day puny humans are capable of splicing genes from multiple species together to create improved organisms, I have little trouble picturing an advanced intelligence picking and choosing all the right genes to create space-hardy creatures. Maybe the zerg even have a little bit of water bear DNA in them!


  1. Steven

    SOOO cool. So well thought out and not too far fetched. Please don’t stop doing this.

    • Ryan

      Thanks, I’m glad you’re enjoying the articles!

  2. Kevin

    I hear mention of an experiment on the space station that involved mosquitos in some life stage that were able to survive some time outside of the ship. Was that just the waterbear thing incorrectly reported?

  3. Joseph

    Some of the Zerg are known to have internal gas bladders (e.g. overlords). That might help for oxygen storage or some other space-survival issues.

    You know, I think you may have accidentally identified another function of the creep. As you said, a high surface-area-to-volume ratio would help with thermal management as the Zerg probably produce a lot of waste heat. Perhaps Zerg on the creep are able to use thermal conduction to transfer their own internal waste heat to the creep, which could then radiate it off at a more leisurely pace. Clever mechanisms for storing up and then slowly releasing waste heat have even been used on modern spacecraft. (I leveraged one, from the Apollo lunar rover, for my space-battle short story!)

    Thermal regulation could also be the reason why the Zerg are so spiny, or why the hydralisk has that big fan-crest on its head, or even why they seem to drool so much! Spitting out warm liquids would be quite efficient at cooling the creatures, though they would have to produce cool liquids from somewhere to begin with.

    That picture you chose for the hydralisk also illustrates another thermal-related point: color! The sun in the picture is purple, clearly a different spectral type from our Sun which has its peak somewhere around yellow-green. Zerg carapace colors may be tuned to some sun other than the one we’re most familiar with!

  4. Victor de Souza Magalhães

    Have you ever About Prof Lynn Rothschild, from NASA Ames research center?
    I went to an Advanced school of Astrophysics last week here in Brazil.
    She gave lectures on Astrobiology,
    and she said that in her Lab their trying to create transgenic organisms
    that can live in space!

    • Ryan

      Very cool! She should call her research group the Xel’naga. 🙂

    • Joseph

      That’s way cool! For reference, I found an article she wrote for SpaceRef in 2002, in which she discusses various forms of extremophilia:

  5. Victor de Souza Magalhães

    Let’s send her this sugestion 😛

  6. MiriV

    Actually, according to the lore, Zerg assimilated and evolved ability to travel in space from Behemoths, creatures kind of like manta rays, able to survive in space. More about them on the Starcraft Wiki:

    • Ryan

      Thanks for the link! Although that’s true to the lore, it doesn’t actually answer the question of how they can survive in space. It just defers the question, so it becomes “how can behemoths survive in space?” It makes me wonder who designed the behemoths, because I can’t think of a way for an organism to evolve in space.

      • Anonymus

        Let’s just say the Xel’Naga Did it.

      • Androkguz

        If behemoths come from an very low gravity enviroment then it is easy. Behemoth’s ancestors might have lived in an asteroid field where they could just jump into another asteroid. The same way life eventually go out of the ocean in earth, this creatures got out of their initial asteroid into a zero gravity enviroment. Then flew into a low gravity planet and evolved to come back. And so on.

  7. Steven

    I was thinking about storing oxygen in space, and I figure it could be just dissolved in a liquid that has a low vapor pressure even with the dissolved gas, or in a solid like hydrogen dissolves is metal hydrides. The zerg could just live of these tanks for a while. And if they carried a liquid with the proper boiling point under a little pressure, they could release the pressure slowly and it would boil, carrying away the heat when they got overheated. I’m sure a carapace that can stop tank rounds could be formed into pressure tanks, anyway. Also, mass affect has some pretty good in-game explanations on how those fictional starships stay cool.

  8. Alf

    Firstly I’d like to say all of your posts are amazing, I always liked the mechanics of futuristic things but your posts take it to the next level. On the oxygen issue though, why do the zerg have to use oxygen. It’s a fact my dad and I have gone over a few times when randomly speculating but how do we know there isn’t a totally different periodic table in the universe, not even using protons, neutron and electrons but totally different particles. There’s also the fact that if the periodic table is uniform throughout the universe, the zerg don’t have to breathe oxygen. Why not neon, or helium (I know these aren’t the best biological examples but hey, aliens). If the oxygen problem is eliminated then poof, half the survival problem is gone. And if there’s a source somewhere saying the zerg do breathe oxygen could someone point me towards it?

    • Ryan

      Actually, we do know that the rest of the universe is made of the same elements that we have here on earth because we can identify elements based on their spectra. In fact, helium was discovered on the sun and in stars before it was found on earth! Maybe the zerg don’t breathe oxygen, but they need some sort of fuel for the chemical reactions in their bodies.

  9. Dripable

    Awfully well written article!!

  10. offthegridinperu

    Interesting read, thanks!

  11. lolzor

    I really enjoy this blog; i always loved the starcraft universe and had interest for the zerg too.

    Also; one could theorise that zergs can perform photosynthesis. Melanin is a “super-chrolophyl” and is used by some black molds to grow inside nuclear reactors; it basically works with a wider band than just light. I figure a space-travelling race that has to spend a lot of time with close to no nourishment; and genetically engineered; would have to use photosynthesis for energy.

  12. Houston

    Hi there! Would you mind if I share your blog with my
    zynga group? There’s a lot of people that I think would really appreciate your content. Please let me know. Many thanks

  13. Fede

    Well, maybe they can survive with a low metabolic rate, but what about when they are fighting? We know they fight in platforms, and platforms are open to the vacuum of space.
    Maybe, well, magic.

  14. cepheus

    The zerg such as hydras and lings dont actually survive in space they are carried by lethians which hold oxigen long enough for the zerg to survive aswell as possibly creating new oxigen while in space. but the lethian is able too survive space. mutalisks survive because of there increased lung copassity due to ther thin flexible bodies but i believe do stop in the lethian for air

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