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Thread: Gallilean Moon Life

  1. #1
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    :unsure: :unsure:
    There is strong circumstantial evidence for a global liquid ocean under the ice surface of Europa, and, to a lesser degree, Ganymede and Callisto. If so, it is likely that life has evolved within each of these moons. Let’s speculate that life has arisen and advanced to the multicellular level and brainstorm about what form it might have taken, what sort of ecology might have formed in support of it, and how technologically advanced it may have (can) become.

    Consider:

    What is the level of visible light? Is the level of visible light enhanced by luminescent organisms? What effect does the radiation frequency of peak intensity have on the kind of sensory organs that would evolve? Could an “atmosphere” form between the solid ice surface and the ocean surface? Assuming the more “technologically” advanced critters are crustacean-like (crabs, lobsters, etc.,) or fish-like (gills and fins with fingers), what would limit their cultures and shape their view of the universe? Would the rate of speciation be higher or lower than that on earth? :unsure: :unsure:

    Does this expand the definition of life supporting zones around stars? Quite a few planets have been "discovered" between 0.8 and 1.4 AUs from their parent stars. These planets are of sizes on the order of that of Jupiter and are likely to have moons of sizes on the order of Jupiter's Gallilean moons. h34r:

    Boy! it's getting crowded. Can we hope to compete?

  2. #2
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    An interesting topic.

    I can think of a possible analogy to which to consider - the life forms that are found in the deep oceans of the Arctic and Antarctic, indeed in any deep region - where there is little to no light.

    What would be a chemical indicator of life?

    Also is it possible that Europa especially has internal heating, hence even a europan version of a black smoker in abundance?

  3. #3
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    I think the main constraint on the evolution of these creatures will be the lack of light. I reckon that in a dark, cold environment, most communication will be short-range and tactile. This will make it much harder to gain a mental model of their environment.

    Once the immediate needs of food, shelter and reproduction are satisfied, what's going to drive their exploration of the home planet? They won't be able to stand on a hilltop and speculate on the origin of the millions of stars they can see.

    But on the other hand, maybe that's too anthropomorphic. Maybe a "close-range" environment will drive them to develop mentally and evolve a co-operative society rather than our individualistic, tool-based society.

  4. #4
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    Originally posted by Sp1ke@Jan 23 2004, 02:28 PM
    I think the main constraint on the evolution of these creatures will be the lack of light. I reckon that in a dark, cold environment, most communication will be short-range and tactile. This will make it much harder to gain a mental model of their environment.

    Once the immediate needs of food, shelter and reproduction are satisfied, what's going to drive their exploration of the home planet? They won't be able to stand on a hilltop and speculate on the origin of the millions of stars they can see.

    But on the other hand, maybe that's too anthropomorphic. Maybe a "close-range" environment will drive them to develop mentally and evolve a co-operative society rather than our individualistic, tool-based society.
    Just a thought, but how about sonar? They could see for miles without "eyes."

    I just saw a show about these organisms that live in water caves in Mexico that live in an environment without oxygen or light. The "air" they survive in is almost completely sulfur based. It would kill us almost immediately. Pressure doesn't seem to be a problem for giant squid or even whales. If fish can live in environments with no light, it could be possible for intelligent life to form? Hot or cold temperatures could be overcome to a certain point. But, I do think that intelligent life could form in these types of environments. I think the key is to have a "stable" environment. It is truly tough to speculate though...

  5. #5
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    Its hard not to think anthropogenically here. However, i have heard of life existing on the mid Atlantic ridge near the Arctic Circle, also in a relative stable regions near Arctic Canada.

  6. #6
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    OK, so what would they look like? Maybe the pressure and aquatic environment would favour a slug-like bottom-dweller? Or would the support provided by the liquid allow them to be slender, fragile creatures?

    I think if they are to be intelligent, I think they need to be able to interact with their environment so probably would end up as tool users. This means the slugs would have to have some sort of extendable pseudopods; this might give them the edge over a fragile form that didn't have the strength to manipulate things around them.

    Btw: Good point about the sonar. The problem with that is that I don't know how well it would work if they ever reached the surface. If they used sound waves, they'd not be able to see anything in space because of the vacuum. We're lucky to see in visible light as it allows us to see celestial bodies as easy as we see each other. It would have been a lot harder for us to understand the solar system if, instead of inventing tools to see it better, we had to invent tools just to see it in the first place.

  7. #7
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    I would think that life would be more dependent on the vents near the ocean floor than from sunlight. If they evolved beyond singled-celled organisms, they would most likely be fish-like. Sharks and dolphins are similar, but come from very different parts of the evolutionary chain. I don't know about intelligence, but it could be possible, but it's hard to start a civilization without fire.

  8. #8
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    Originally posted by Sp1ke@Jan 23 2004, 02:28 PM
    This will make it much harder to gain a mental model of their environment.

    This sounds cool what you said. Please explain this a little more. In private if you want.
    h34r:

    Yes that was me....JimN

  9. #9
    GOURDHEAD, I expect there should be simple life on Galilean moons, maybe multicelluar?

    Discussion: Gas Giant Moon type undersea zones could well spawn life. Where the gas giant is within the Solar Habitable Zone such life would have more options such as developing sight and moving onto the surface. Though many gas giants outside of a Hab Zone could well make islands of life that sit isolated below ice.

    Where a gas giant is distant from the star it would tend to have more primary atmosphere and moons would tend to be swamped with oceans miles deep. Eventually any star that is not K or M class will start to evolve off the main sequence, getting bigger and hotter. In such cases "Isolated Island Hab Zone moons" could well move into a Solar hab zone, which could lead to sophistocated life if the star evolves slow enough. Also bigger stars have wider hab zones hence may get 100's of millions of years before the hot sunward margin of the hab zone reaches the planet.

    Where a gas giant is nearer to the star more primary atmosphere will have been plucked away by solar wind or ignition of the star, hence land would be more possible and things would be brighter, hence more possibility of Earth type life the is visual and slithers from seas to the land.

    Makes me think of a new definition
    SOLAR Habitable Zone - Zone in which Solar energy will allow free water on a planets surface - naturally environments that would not be too hostile to our type of life.

    GRAVITY Habitable Zone - Zone in which tidal forces from a Giant Planet will provide alternative energy sources to a moons potential ecosystems. For example Hydrothermal or Volcanic vents under pack ice - maybe allowing some forms of Earth like life, much like those around many vents.

    Earths first life was suspected to rely on geothermal energy, then as it developed some groups adapted to other sources like solar energy (plants - reptiles) and thence carbohydrates (mammals) etc.

    Consider Sol and similar G2V systems: the hab zone ranges from 0.7 AU to 1.6 AU, @ .9 AU wide and is "sweeter" in the middle. As the star ages the hab zone moves out too. Hence smaller G class suns hab zone will move across a typical planets orbit quicker, while the shorter lived larger G class stars will have a wider zone that is "good" for longer in any one planets orbit.

    Also any gas giants in a G2V system probably have a GRAVITY have zone either beyond or within the SOLAR hab zone in which moons will experience tidal forces. Hence small islands of life zones not dependant on solar distance/intensity.

    I'm rather interested in the brighter stars - Consider that the F2V SOLAR hab zone is around twice as wide as G2V's. Consider Deneb Algedi's A6V SOLAR Hab Zone @ 3.5 AU wide, Sirius @ something like 6 AU wide spanning 4AU - 10AU. Makes me think the bigger stars have a much wider zone to potentially host "good" planets.

    The bigger the star the shorter lived though, hence Sirius would not have time to develop sophisticated life (500 million years) while an F2V probably could?

    More common bigger K2V class stars have a life zone averaging around .2AU - .7 AU = half as wide as a G2V, and even more common M class stars pretty much are limited to a "tidally locked torch orbit" for any SOLAR hab zone planets. This does leave a huge scope for gas giants with a GRAVITY hab zone = Blind creatures. Where I am going here is the opinion that smaller stars may have as much life potential, but it would not be visually orientated as we are. Red Dwarfs are around for ages, non should have burnt out yet as the Solar life of such a star exceeds the age of the universe, hence many of these would have allowed plenty of time for life to generate in the GRAVITY hab zones. Maybe the star it self could generate "GRAVITY hab zones" on smaller rocky inner planets - allowing another alternative form of a hab zone.

  10. #10
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    Calibre: Great review/summary of possible habitable zones.

    I'd like to see more brainstorming about the evolution of electromagnetic radiation sensing organs. Evolution is a success driven process in each of the reproduction and maintenance dimensions of life. Mother Nature blindly and mindlessly tries all sorts of combinations and permutations of traits for organisms; consequently,
    "eyes" sensitive to various bandwiths of the em spectrum can arise in just about any environment where the selection pressure is not prohibitive. Also, in the dimly lit (in visible light) portions of the the earth's oceans there are critters capable of phosphorescence (for the lack of a better word) like processes for light generation to aid them in mating or eating or both. In the Gallilean moon type environments phosphorescence may have been developed to a much higher level than here on earth. It would endow its possessors with quite an advantage as well as increase the selection pressure thereby escalating the race to better vision and then to intelligence. Intelligence begets curiosity begets exploration begets breaking through the ice surface begets technology development to deal with the vacuum begets exploring the surface begets launching themselves into the universe. Stay tuned!!!

    Although I am not aware of any earth critters having developed hypergolic capabilities, I know of no reason why Mother Nature wouldn't (hasn't)
    experiment(ed) with such a feature (could stories about fire spouting dragons have origins in the species memories of humans). Consider a critter equipped with bladders each holding a stable chemical which, when mixed with the other outside its body, creates a hyperactive solution very useful for boring holes in enemies, predators, rocks, ice, etc., Such a feature might have a decided survival advantage for the species possessing it, and its competition with similarly equipped species would accelerate the drive to intelligence.

    This is an example of the brainstorming I'm looking for. Let's rev up those imaginations!!

  11. #11
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    A creature that could sense radio waves would be great at astronomy but I suspect they wouldn't provide a very detailed picture of nearby surroundings.

    So going the other way, what about detecting very short wavelengths? That would provide a very detailed picture of nearby objects. If you imagine life on a very small scale, that would be more relevant. So an entire race of bacterium-sized beings that saw using x-rays?

    Or going back to the big stuff - if something could tap into the magnetic field of a planet, or even its sun, could it use the entire field to sense things? Kind of like a spider's web, it could detect anything that moved within the magnetic field. How about an eye the size of a planet!

  12. #12
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    It'd cost a fortune in contact lenses! :P :P

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