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Complex Life With No Atmosphere
Topic Started: Jan 19 2010, 12:36 AM (1,379 Views)
TheBioBassist
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I have been wondering if complex life could possibly survive on a planet with enormous temperature swings such as the planet mercury (−183 °C to 427 °C). Is it possible for life to be subterranean and use the temperature change near the surface to create a gradient with the more constant temperature found in deeper layers? Could life use such a gradient for energy? Is anything like this found on earth? I also imagine such thermal powered "plants" to be heavily dependent on animal pollination and seed dispersal as it would be the most effective method underground. Maybe even creating large corridors to encourage animal visitors.

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Empyreon
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Are you plausible?

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I have been wondering if complex life could possibly survive on a planet with enormous temperature swings such as the planet mercury (−183 °C to 427 °C).


Wow, that's a big swing. Such talk brings to mind the existence of extremophiles, life forms that thrive outside the range of what humans (and similar life) can survive. My question is: is there such a thing as an extremophile can can survive hot and cold?

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Is it possible for life to be subterranean and use the temperature change near the surface to create a gradient with the more constant temperature found in deeper layers?


That's the right direction to go with something like this. With surface temperatures so extreme, then there would be no atmosphere. Any volatiles would have to be found trapped underground.

As far as utilizing the energy gradient, I'm not sure how it would work. Sometimes the best thing to do is sketch things out visually in a diagram. Those always help me figure out the logistics, but then again I'm a visual learner...

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Is anything like this found on earth?


Are the creatures that feed off the volcanic vents at the bottom of the ocean anything like this, or are we talking about another thing entirely?

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I also imagine such thermal powered "plants" to be heavily dependent on animal pollination and seed dispersal as it would be the most effective method underground.


But what did they do before animals were around? It's all well and good for them to develop a relationship with their animal counterparts but, generally speaking, plants usually show up first. Maybe they develop something effective enough to make pollination and animal distribution completely unnecessary...
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food for thought
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KayKay
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It's not necessary for plants to show up first, you just need a primary producer first. It could even be rock-eating bacteria.
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T.Neo
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Life needs a solvent, and solvents for life are essentially limited to liquids. Liquids cannot exist in a vacuum- they'll boil away.

So life will have to have a "shield" of sorts; a pressure vessel.
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sam999
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If there was ice like some people think lies under the poles of mercury gravaty tides from the sun might melt some of it deep deep down and life might form. It would be somewhat like our JIM project in how it worked however.
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Empyreon
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Are you plausible?

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If there was ice like some people think lies under the poles of mercury gravaty tides from the sun might melt some of it deep deep down and life might form.

Sounds a lot like the generally accepted conditions found on Europa.

One thought comes to mind. We speak here of developing complex life without an atmosphere, but what does that mean? It's true that planets so close to their star (or too small to retain it) don't have a gaseous atmosphere, but couldn't we consider the solution the life evolves in to be an 'atmosphere' all its own? What exactly do we mean by "no atmosphere"?
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food for thought
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Ànraich
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It would have to overcome several obstacles, and would be very unlikely, but it is possible.

First of all, it needs a solvent. As Sam mentioned, it could be gathered from water ice, or perhaps there could be things like aquifers, vast underground lakes (maybe not vast by our standards, but by the standards of a planet without an atmosphere). So long as there is no holes connecting the aquifers to the surface, they won't boil away, as they'll be pressurized.

Secondly, life needs not just a liquid solvent, but a gas to use in metabolic reactions. Atmosphere could exist in caves, given they have the same prerequisite as aquifers. It would be made mostly of volatile volcanic gases, but surely something could utilize it, and even make pockets of oxygen-based atmospheres beneath the surface. Now then, if there is absolutely no atmosphere, then it would either be limited to the aquifers, or perhaps find a way to break down water/water-ice for usable gases. Or, maybe, life here has found a new way to undergo metabolic reactions, perhaps it doesn't even acquire usable energy the same way as our cells (ATP).

And finally, with no atmosphere there is no pressure. Organisms like ourselves would depressurize and our liquids would boil away inside of us. Life on a world such as the one you describe would need to either live in water, or be self-pressurized. Skin as we know it won't accomplish this, but exoskeletons could manage it. Given that the size of animals would be limited, but small is better than nothing.


I'm more interested in what kinds of senses these organisms would use to get around. They would have to live underground, and there would be little to no air down there (unless it was a pocket-atmosphere or aquifer). They would have no eyes or ears, due to lack of air for sound. Likewise they would have no sense of smell, as scents need a medium to pass through. How would they detect changes in their environment or other organisms? How would predator find prey, and prey sense predator? Perhaps they're very sensitive to vibrations in the rocks they crawl on? Or maybe there are plants that use chemosynthesis (breaking down minerals in the rock) and end up glowing in this process, giving light to see by?
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Venatosaurus
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Or maybe they can detect, or even 'see' eletrical impulses within the bodies of other organisms. But could an 'atmosphere' exist underground, maybe pressure could be created my the mass of the planets core, but could the elements necessary be found underground (completely sealed off mind you) and provide the necessary components , and possibly some sort of elemental combination that gives off some sort of light, or even a glow ? Mind you, I think all of which I stated is impossible, or very unlikely, but I just wanted to present some other options or ideas.



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TheBioBassist
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"One thought comes to mind. We speak here of developing complex life without an atmosphere, but what does that mean? It's true that planets so close to their star (or too small to retain it) don't have a gaseous atmosphere, but couldn't we consider the solution the life evolves in to be an 'atmosphere' all its own? What exactly do we mean by "no atmosphere"?"
This is true empyreon that i guess an atmosphere does not need to be gaseous but instead is whatever the organism lives in. And as for liquids and gases being sucked into space are there compounds or elements that are liquid in a vacuum and could be the solvent these organisms could use.
Also as for the "plant" reproducing without animals they could possibly use structures similar to the hyphae used by fungi.
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Venatosaurus
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New thought, what if the waste form these subterranean organisms contain vital, atmosphere making chemicals and elements ! Thus an atmosphere could be achieved !



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TheBioBassist
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Then definitely seems plausible as oxygen makes up almost 50% of earths crust. Bacteria feeding on chemicals found within the rocks could possible release oxygen as waste
"The most exciting phrase to hear in science, the one that heralds new discoveries, is not "eureka" ( I found it) but "that's funny......""
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Venatosaurus
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Yes, or even methan, nitrogen, phosphorus, carbon, whatever really ! Especially if organisms can convert one product into another, similar to Earth's plants converting CO2 into O2 ;)



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T.Neo
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So long as there is no holes connecting the aquifers to the surface, they won't boil away, as they'll be pressurized.


Indeed.

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Secondly, life needs not just a liquid solvent, but a gas to use in metabolic reactions.


Right, this is why fish need to breathe air.

I can understand life needing dissolved gases (as fish indeed do), but not free gas.

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Skin as we know it won't accomplish this


Why not?

Spacesuits already use a sort of "skin" that is flexible, airtight etc. There are even "skin-tight" suits being studied that are essentially an extension of the astronauts's skin; the suit maintains the pressure by pushing on the skin, not by introducing a pressurised atmosphere.

AFAIK, moving in these suits is quite easy.

I could imagine a biological version of this working quite well.

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Given that the size of animals would be limited, but small is better than nothing.


Why would they have to be small if they had an exoskeleton?

If the exoskeleton "grew", like vertebrate bones, it wouldn't have to be shed and thus the organism could grow bigger.

I doubt anything really big would evolve anyway.

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They would have to live underground,


Cave creatures already do this. Deepsea vent communities also live in total darkness.

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They would have no eyes or ears, due to lack of air for sound.


If they lived in water, they could definitely use sound, and as an extension, use echolocation. As could they use scent, as smell works well underwater.

On the surface, there would be no sound, so hearing would not be possible. But sight could happen, if the eye lenses were solid and made out of silica, like trilobite or Snaiadi vertebrate eyes.
Edited by T.Neo, Jan 20 2010, 08:58 AM.
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Are you plausible?

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Why would they have to be small if they had an exoskeleton?


It's generally understood that an endoskeleton works better for larger life forms than an exoskeleton. But since an exoskeleton would be so useful if a creature were to go onto the vacuum-exposed surface of the planet, an exoskeleton would be very handy. What if they had both? Or what if the planetary gravity is such that the bulk of an exoskeleton isn't really that much of a hindrance?

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If they lived in water, they could definitely use sound, and as an extension, use echolocation. As could they use scent, as smell works well underwater.


I agree. Sound doesn't need air to transmit, it needs a medium. That can be air, liquid, solid rock, anything (though some media are better at transmitting sound waves than others). Heck, I could even hear you through grape jelly! ;) Echolocation would be an effective sense in these dark subsurface pockets of life, as would smell and even electroception.
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food for thought
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T.Neo
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It's generally understood that an endoskeleton works better for larger life forms than an exoskeleton.


Of course, but an exoskeleton surely shouldn't restrict you to insectile sizes.

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Heck, I could even hear you through grape jelly!


You're disturbing me now. :P
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