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They say that nature abhors a vacuum, but could life evolve to live in one? Alternately, could life be engineered to exist on a planet with no atmosphere, even if there is no biologically feasible path through which this life form could evolve?

By vacuum, I mean 'no atmosphere', but with ground. Something like the moon, rather than something like deep space. If life in a vacuum is possible, what I'm really interested in is this: what would the life forms be like? What adaptations would they need to cope with life in a vacuum?

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Theoretically, a planet with a hard, gas-impermeable crust and no atmosphere could support life in subsurface rivers which were warmed and mineral enriched by hydrothermal vents. The crust would keep the rivers from evaporating while life took hold and evolved. Later, when that life was sufficiently advanced, the crust might crack, slowly venting away the rivers into outer space. Over millenia, while their native environment slowly dried up, the life could evolve and adapt.

At a minimum, it would need the ability to consume minerals in solid form, without the need for suspending them in a liquid medium. They would need an impermeable shell to keep their vital fluids from evaporating. And they would need some form of energy production to fuel their motion and cellular growth. Perhaps natural solar panels could fill that last role.

Sounds like I've just described an armoured form of plant life...

Throw in a redundant, error-correcting genetic structure to handle the inherent radiation, and I think you've got an empty space life form on your hands.

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I could see life forms adapting to live in a vacuum, but to just come into being, is unlikely because you need chemicals and chemical reactions to make life.

Living in a vacuum the life would have to have a good shell of some kind to seriously control the movement of atoms both into it ('eating', 'respiration') and leaving (waste).

I would expect it to have several catalyst reactions to recycle as much of it's waste as possible, and it should have a generally low metabolism or at least can go dormant with only a few autonomic systems working to wake it up should things change, such as more food/water/air becomes available for it to continue its processes.

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For life as we know it: It does not.

The way biological processes work a relatively high concentration suspension of chemicals in a fluid over significant period of time and volume of space is required. Fluids evaporate if pressure is too low. Vacuum has very low pressure.

Life that evolves inside an asteroid or moon that lacks atmosphere might be possible. Although maintaining fluid environment over long period of time would probably result in a trace atmosphere.

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I would have thought it could survive in a vacuum.

Fundamentally, all life needs is energy. Everything else is a means to an end. If an organism were designed to make use of the higher solar radiation possible without a pesky atmosphere in the way, it could do very well out of the whole thing. Terrestrial-style grass might even be possible if the grass is designed in such a way that it can take all the oxygen it requires from the soil or rock present. When the plant dies, the minerals are returned to the soil and new plant life can spring up. I'm not sure how far along you could get, but an entire non-breathing planet could be plausible.

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  • $\begingroup$ except water instantly evaporates into a gas on the surface of these planetoids. :D $\endgroup$ – hownowbrowncow Apr 21 '16 at 17:33
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What do you mean by "evolve" here?

I do not believe that life could originate in vacuum. Very primitive life requires hospitable conditions and space doesn't qualify. You need a shell that can retain your solvent and you need radiation protection.

That does not preclude life in a vacuum, though. Look at the extremophiles--they live in conditions that would have immediately destroyed primitive life but they were able to adapt over time. Take a world like Mars--I wouldn't consider it impossible for life to have evolved defenses that allowed it to continue as the atmosphere bled away over the eons. You could even get outer-space life this way--take a lifebearing planet, slowly bleed the atmosphere and then knock it into the sky in a big impact event.

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From this article on the NASA website

Living things tend to be complex and highly organized. They have the ability to take in energy from the environment and transform it for growth and reproduction. Organisms tend toward homeostasis: an equilibrium of parameters that define their internal environment. Living creatures respond, and their stimulation fosters a reaction-like motion, recoil, and in advanced forms, learning. Life is reproductive, as some kind of copying is needed for evolution to take hold through a population's mutation and natural selection. To grow and develop, living creatures need foremost to be consumers, since growth includes changing biomass, creating new individuals, and the shedding of waste.

I suppose it depends on how you want to define life.

The definition of life above could easily exist without an atmosphere, the issue of breathing, which I'm assuming you're mainly referring to when thinking of an atmosphere (ignoring the radiation and vacuum issues for the moment), is simply part of the energy intake process that we've evolved into (more info here).

So, the first adaptation is an alternative form of energy intake, such as solar (since you gave the surface of the moon as an example, lets go with that).

The vacuum question is, to my mind at least, one of pressure. Human, and other creatures that have evolved to live at sea level (i.e. at 1 atmosphere, or 1 bar) don't tend to do well is low pressure environments. The Death Zone of Mt. Everest springs to mind.

In a vacuum, there isn't a lot of ambient pressure, so unprotected humans don't do too well.

So, as alluded to by other answers, creatures with a tough exo-skeleton can survive in a vacuum for short periods, as can space suit wearing humans. Deep sea marine life also has adaptations to deal with non-sea level pressures.

What would life in the absence of an atmosphere look like? Consider the following:

  • Creatures with tough, possibly exo-skeletal type bodies, such as robots or beetles
  • Gaseous creatures without solid bodies, i.e. sentient clouds
  • Pure energy beings, think... something you can't see that can only communicate by varying it's own energy expenditure
  • Beings large enough to have their own atmosphere and creatures living on them, such as Earth
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Some people addressed the question of "possible life forms that would evolve" rather than point out that life on Earth as we know it would not work. I will keep going in that direction.

There's nothing about our specific nature that makes us more alive than a completely neutral object like a rock. Even though plants are made up of complex cels like animals are, a plant is more like a highly dynamic static object such as a rock, while animals containing a nervous system are able to store information and act, anywhere in the range of a jellyfish (non centralized nervous system but still maintaining an energy state) to a human (highly centralized and more information stored and manipulated).

So, for the question of life, let's start with finding if an energy state can be maintained rather than the typical reproduction centered meaning of life.

I think most of what we consider life is an insulating membrane, and the ability to take input and produce output in a controlled, predictably beneficial way. Mitochondria (energy production organelle) do this, and they are theorized to be the first kind of living organism. They also have their own DNA.

One could theorize that the very first existence of life was slice of DNA-like reproductive material, which in some medium was able to influence the creation of some type of protein-like molecule that enabled more reproduction of the material and thus more production of the protein. Basically it was taking energy from the environment and threading it along some delicate pathway. It is unique form of chemical reaction, in that it leaves a memory of itself in different forms as the DNA-like material. Thus, as it multiplies and tweaks the reaction, it is able to try many forms with the hope of identifying a new path-of-least-resistance, while not abandoning previously successful forms.

Eventually, the reproductive material that produces the protein and reproduces itself starts reproducing itself with a sequence that codes for a protein that influences the development of a membrane, which has a positive effect on the reproduction/proteins system. This is the basic theme established- a system based on stored information that drives a specialized metabolism will establish ways to ensure a controlled development. It's a positive feedback loop that implements its own homeostatic environment. This theme should carry us from a Mitochondrion, to a cell, to a multicellular organism, to a human with a brain.

I could see "gaseous cloud" beings as someone mentioned, possibly having some type of light membrane material inside of and around itself. I could also envision something evolving in liquid rock and possibly engineering a way to leave access the surface. There could be a type of chemical stew that produces a really good insulating material, and this could exist in a vacuum. Like rubbery chemical beings. One could wonder if metal could become sentient if it was able to manipulate a charge.

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  • $\begingroup$ Could you expand on your rubbery chemical beings it interests me alot $\endgroup$ – Amoeba Jan 13 '18 at 22:57
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Make them out of metal, metal plants and animals could survive in space on planets and off of them.If it were somehow possible for biological processes to be replaced with metal versions, giant metal whales could fly through space towards nebulae and planets to eat the raw resources and melt them down in "furnace" like stomachs, perhaps after churning them in huge tungsten blenders?

Either a nuclear reactor or chemical reactions could be used for power, for example, Thermite to make stomach, electricity produced by hydrogen reaction etc..

Smell and Taste would detect trace quantities of useful minerals and gas. Hearing would only be possible near celestial bodies where there are gases in space

Feeling would be the same as normal, and Seeing could be done using solar panel like cones and rods or better. Detecting cosmic rays would be useful

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    $\begingroup$ Welcome to Worldbuilding SE, Sam! It sounds like you're suggesting metal robots or automatons of some sort. While these might meet some definitions of "life", and the question did allow for "engineered" solutions, can you elaborate a bit more on how these creatures would be alive? Such as, how would they meet the typical requirements of growth, reproduction, functional activity, and continual change preceding death? (That's a Google dictionary definition, but feel free to reference an alternate definition, as long as you can back it up.) $\endgroup$ – type_outcast Jan 10 '16 at 22:03
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Yes, such a life form can exist. In fact, more than of them does exist and is known right now on Earth. They are all microscopic, so that may not be what you are looking for exactly, but if individual cells can survive I imagine that a multicellular organism is at least possible. It is because of the existance of these organisms that space agencies consider it so important to build their satellites and other machines to go to space in a clean room (there are other reasons as well) as to avoid adding Earthly life to a planet or moon in order to cause a false-positive for extraterrestrial life.

At the end of this page there is the following quote:

The duration of the study was short. However, researchers believe that the experiment results provide evidence that hardy organisms could survive in space for millions of years [on an asteroid] before landing on a planet.

I think that an asteroid would provide very similar conditions to living on a body like a moon as gravity seems to even help some microbes.

If you want a method for this to happen naturally, then simply have a similar organism evolve on an Earth-like planet, use any of the numerous methods described here to get it into space, then have it land on a moon-like body where it then further evolves as needed.

One of the (according to my previous link) most likely methods for the bacteria to leave a planet is for radiation pressure from that planet's star to push them out of the gravity well which, according to that page, is possible as bacteria are so small.

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We can try engineer insects to live in a vacuum. I start with insect, because they have exoskeleton which is already a good start for a spacesuit, plus some of them are excellent jumpers, which could be a very good solution to move around in a small planet with no atmosphere (can't fly there). The problems are three: water, radiation and oxygen.

Oxygen is the simplest, they could get it in solid form from minerals; also, we already know of multicellular organism that live without oxygen.

Radiation is also easy (somewhat) just give each of their cells some of these guy's repair mechanisms. Or else maintain a stock of stem cells to replenish the damaged ones.

Water is the real problem, in a vacuum all water will slowly evaporate no matter how tight is your skin, so either you have a big reserve of water or I dunno. Tardigrades can survive in vacuum for a while by dehydrating, but need water afterwards, maybe the water could be jellified to prevent its escape (chemical reaction would be considerably slowed, but with an electrically based nervous system your animal can still be fast).

What they eat is another problem, are there plants? Or are they lithotrophic? Thermal radiation is another concern. Your animal need a system to radiate heat away, maybe their skin is covered with gold or photonic crystals like butterflies' wings to reflect the incoming sunrays. You can also consider making them photosynthetic.

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