Is a space-based lifeform possible?

[CaptainChewbacca]

We've seen mynocks and xenomorphs, but is it feasible that there could be a creature which evolves and thrives in the vaccum of space? Would it be a ship-eating monster, or some sort of bogey which eats comet fragments?

[GrandMasterTerwynn]

We've seen mynocks and xenomorphs, but is it feasible that there could be a creature which evolves and thrives in the vaccum of space? Would it be a ship-eating monster, or some sort of bogey which eats comet fragments?

Probably not.

For a life to evolve, you need a concentration of the essential building blocks. A high concentration. Cold molecular clouds are dense, relative to the interstellar medium, but they're still more sparse than the high vacuums achieved under laboratory conditions on Earth. You also need energy input to drive the prebiotic chemical reactions. In a nebula, the only energy input will come from supernovae, and the solar winds of newborn stars. This isn't a lot of energy, but it's still enough that we get simple organic compounds in large molecular clouds. The more complex molecules required for life require higher energy inputs to create, but when you get close enough to a star to get those inputs, such molecules will likely be destroyed by hard radation . . . unless sheltered on a planet, or a reasonably large body packed with organic material, say a comet.

If one imagines a large cometary nucleus that spends the early part of its history relatively close to it's parent star, (but not so much of its history that it boils off all its volatiles . . . let's say an encounter with one of the star's newborn gas giants knocks it into a long-period orbit,) and we assume that the reactions that produce basic self-replicating life arose really quickly, and that these self-replicators became extremely hardy microbes, then yes, you can envision life that didn't evolve in the shelter of a large terrestrial planet or moon. It won't be very impressive. You'd need a microscope to see it, and it would likely reproduce and live very slowly, over the course of thousands, or tens of thousands, of years . . . so it wouldn't look all that alive.

Mind you, the odds of all these assumptions occurring at once, resulting in abiogenesis in the comet, are vanishingly slim, compared to the odds of it happening on a terrestrial planet. (For one, planets are bigger, better protected, and have more consistent environments which can be favorable for the generation of life. Not to mention a planet is so large that early life can arise repeatedly across wide areas of the world.)

[Molyneux]

We've seen mynocks and xenomorphs, but is it feasible that there could be a creature which evolves and thrives in the vaccum of space? Would it be a ship-eating monster, or some sort of bogey which eats comet fragments?

Probably not.

For a life to evolve, you need a concentration of the essential building blocks. A high concentration. Cold molecular clouds are dense, relative to the interstellar medium, but they're still more sparse than the high vacuums achieved under laboratory conditions on Earth. You also need energy input to drive the prebiotic chemical reactions. In a nebula, the only energy input will come from supernovae, and the solar winds of newborn stars. This isn't a lot of energy, but it's still enough that we get simple organic compounds in large molecular clouds. The more complex molecules required for life require higher energy inputs to create, but when you get close enough to a star to get those inputs, such molecules will likely be destroyed by hard radation . . . unless sheltered on a planet, or a reasonably large body packed with organic material, say a comet.

If one imagines a large cometary nucleus that spends the early part of its history relatively close to it's parent star, (but not so much of its history that it boils off all its volatiles . . . let's say an encounter with one of the star's newborn gas giants knocks it into a long-period orbit,) and we assume that the reactions that produce basic self-replicating life arose really quickly, and that these self-replicators became extremely hardy microbes, then yes, you can envision life that didn't evolve in the shelter of a large terrestrial planet or moon. It won't be very impressive. You'd need a microscope to see it, and it would likely reproduce and live very slowly, over the course of thousands, or tens of thousands, of years . . . so it wouldn't look all that alive.

Mind you, the odds of all these assumptions occurring at once, resulting in abiogenesis in the comet, are vanishingly slim, compared to the odds of it happening on a terrestrial planet. (For one, planets are bigger, better protected, and have more consistent environments which can be favorable for the generation of life. Not to mention a planet is so large that early life can arise repeatedly across wide areas of the world.)

Pat Murphy/Max Merriwell had an interesting idea of metal-eating "spiders" evolving from silicon-based microbes in an extremely dense dust cloud, over an extremely long period of time, in "There and Back Again"...don't know how feasible it is, but it sounded like it made sense.

Of course, the next logical question if the answer to the first is a definitive no is, "CAN there be any form of life which can survive in space, whether naturally created or artificially designed?"

[Castor Troy]

They'd probably be silicon based lifeforms, more like plants, living off of comets, perhaps. I guess they'd have a crystalline form, as well.

[wolveraptor]

It depends on what your "life" is made of. Molecular life probably needs the heat and density of a planet to arise, and unless somehow they migrate into space, I can't picture a lifeform like that.

One book I've read speculates that life could be based off magnetism, making barriers such as heat and density irrelavent.

[GrandMasterTerwynn]

They'd probably be silicon based lifeforms, more like plants, living off of comets, perhaps. I guess they'd have a crystalline form, as well.

The problem with silicon as a basis for life is that it cannot form the complex molecules that carbon can. The resulting chains tend to be brittle and break down before you get something sophisticated enough to reproduce itself (the largest known silicon molecule has just six silicon atoms in it, compared to the tens of thousands of carbon atoms in some carbon-based molecules.) Other problems are detailed here.

So, essentially, when we talk about naturally occuring life, the only game in town is carbon.

[Admiral Valdemar]

Terwyn beat me to it, but yes, silicon is pretty impossible. The best you could hope for is ammonia and even then it's nothing like as good as carbon.

[Zero]

What I have to wonder is, if there was an artificial stable environment that was kept in freefall, could there be life forms that develope in no gravity? There's still constant heat, air, and a good deal of organic material. Could life evolve to fit no gravity? If so, what kinds of forms would such life take? Just a thought. If it deserves a new thread, and would pull this one off topic, somebody be sure to tell me.

[SirNitram]

We've seen mynocks and xenomorphs, but is it feasible that there could be a creature which evolves and thrives in the vaccum of space? Would it be a ship-eating monster, or some sort of bogey which eats comet fragments?

No damn clue. But there's a nebula made of sugar out there. So maybe.

[Solauren]

I can see life arrising in a gas giant or a nebula that could survive in space. Nebula is more likely

[Broomstick]

What I have to wonder is, if there was an artificial stable environment that was kept in freefall, could there be life forms that develope in no gravity? There's still constant heat, air, and a good deal of organic material. Could life evolve to fit no gravity? If so, what kinds of forms would such life take? Just a thought. If it deserves a new thread, and would pull this one off topic, somebody be sure to tell me.

Look at the sort of life-forms we have in the open oceans - things like jellyfish, for instance. Animals with neutral bouancy live in an enviroment that in many ways is like a micro-gravity situation.

[wolveraptor]

Terwyn beat me to it, but yes, silicon is pretty impossible. The best you could hope for is ammonia and even then it's nothing like as good as carbon.

What about under much hotter, higher-pressure conditions, where silicon (I think) doesn't collapse into crystal form so readily.

[Zero]

Look at the sort of life-forms we have in the open oceans - things like jellyfish, for instance. Animals with neutral bouancy live in an enviroment that in many ways is like a micro-gravity situation.

The difference is, it's a bit harder to propell yourself through air. I don't know if this would make a significant difference, but I'd assume so. I can swim, but I can't fly, so this is an indicator to me. However, I guess less pressure can be good, as well, for movement, since there would be less holding you back. Also, since there would be much less friction, even if these creatures moved slowly, they wouldn't slow down without a bit of effort, so they may have significantly lower caloric needs. I don't really know what I'm talking about, though... I'd appreciate some input from a higher authority.

[RedImperator]

I can see life arrising in a gas giant or a nebula that could survive in space. Nebula is more likely

Nebulas aren't dense enough, and gas giant creatures will depend on conditions within the gas giant to survive (not to mention, how would they achieve escape velocity?)

I can't think of any way that life as we know it could nautrally evolve in space. I can concieve of artifical life forms easily enough--self-replicating robots come to mind--but I just can't see natural life, unless it's something truly exotic like life based on distortions of spacetime or something.

[GrandMasterTerwynn]

Terwyn beat me to it, but yes, silicon is pretty impossible. The best you could hope for is ammonia and even then it's nothing like as good as carbon.

What about under much hotter, higher-pressure conditions, where silicon (I think) doesn't collapse into crystal form so readily.

Silicon still doesn't form a lot of interesting molecules. As I mentioned before, the largest silicon-based molecule ever observed only contains six silicon atoms. And silicon compounds tend to lack "handedness" which many complex carbon compounds contain (for example, the amino acid L-tryptophan found in turkeys is a left-handed amino acid.) And handedness is apparently essential in a lot of what is needed to form interesting compounds that would be useful to life.

[Glimmervoid]

There is this animal called a water bear.

http://images.google.co.uk/images?q=wat ... a=N&tab=wi

It was (by accident) sent up in to space on the side of a moon lander (?) any way when it got back it was fine. Having been exposed to hard vacuum.

It can also be frozen in liquid nitrogen and still be ok when it comes out.

[wolveraptor]

That's cheating. The waterbear shuts itself down (in a manner of speaking) in order to survive those conditions. It needs to come back to the warmth eventually (though they can survive for a hell of a long time). Furthermore, the water bear would never be able to reproduce and live completely in space.

[SyntaxVorlon]

There is a silicon based form of life that could thrive in space, robots. Sapient AI sent out to live in deep space could live out in the asteroid belt forever.