5 ms·

It's incredibly cold in the outer solar system right? So why is it that there is liquid water in these moons? Is it some sort of geothermal heating? What's t

It's incredibly cold in the outer solar system right? So why is it that there is liquid water in these moons? Is it some sort of geothermal heating? What's the most complex life which could conceivably exist in such a cold environment? Presumably there's very little sunlight penetrating through the ice to the liquid ocean.

sanxiyn 4y ago
From Earth's hydrothermal vents, we know sunlight isn't necessary for life although energy is.
- Mistletoe 4y ago
  We don’t know if life started in the light though and then migrated to the vents and adapted. My memory of it is that this is an unanswered question so far.
  - causality0 4y ago
    We know that life is older than photosynthesis. I'm not aware of another light-dependent metabolic process that could predate chemosynthesis.
  - dcminter 4y ago
    It's definitely an open question. But in his book "The Vital Question", Nick Lane makes an interesting case that they're actually the origin of all life: https://nick-lane.net/books/the-vital-question-why-is-life-the-way-it-is/ https://nick-lane.net/books/the-vital-question-why-is-life-t...
- peter303 4y ago
  Its a good hypothesis that life start at deep volcanic vents. Geologist Robert Hazen conducted lab experiments showing that all steps of the metabolic citric cycle occur in this environment without needing catalytic enzymes. Chemical reduction of magma provides the energy. As life developed enzymes to improve metabolism, it could migrate to colder, lower pressure environments.
akiselev 4y ago
Tidal heating [1] [1] https://en.m.wikipedia.org/wiki/Tidal_heating https://en.m.wikipedia.org/wiki/Tidal_heating
- Aardwolf 4y ago
  Interesting stuff! Made me find that even rogue planets (free floating without orbiting any star) might theoretically be warm enough to support oceans and life: https://en.wikipedia.org/wiki/Rogue_planet#Warmth https://en.wikipedia.org/wiki/Rogue_planet#Warmth
  - PaulHoule 4y ago
    Could be either tidal or geothermal. It’s been conjectured that even Pluto could have liquid water inside. The point is that generic small outer solar system bodies have liquid water, whereas the generic inner solar system body doesn’t. If you think liquid water is the most important requirement for life then most of the habitat in the universe is outside the frost line. It’s totally plausible that simple life could form around geothermal vents on such a moon but harder to believe you could support a complex ecosystem enough to evolve intelligent life without sunlight. At the high pressures in such an underground ocean I wouldn’t expect our proteins to work, you can kill bacteria with very high pressure. I suspect that proteins that evolved in that environment could work just fine. I can picture a creature from that kind of world drilling up to the surface somehow, but the low pressure would be deadly and in a system like Jupiter where Io ‘breeds’ radiation (vapor from volcanos gets ionized, gets accelerated, ionizes more vapor) the surface could be a dangerous place. Such a creature though might have a leg up on starfaring as getting into orbit might be easier (never mind building a beanstalk) and rather than being tempted by boring destinations like Mars (smaller planet, smaller civilization) they might go straight to cutting up wet/carbonaceous asteroids to build large (100-1000x more habitable area than Earth) habitats and if they developed D-D fusion they might be quicker to see the advantages of a comet-hopping lifestyle.
    - lumost 4y ago
      One of the Main limiters with underwater intelligent life would be industrialization. How are you going to use a steam engine underwater? What do you burn to heat it? Given that geothermal vents would be the source of life for such a species - capping them for machinery would also be unwise.
wkat4242 4y ago
It's also awash with radiation from Jupiter. If there's life, it won't be as we know it :)
- zirgs 4y ago
  Water is really good at radiation shielding.
  - jvanderbot 4y ago
    I've heard that if you swim into a nuclear reactor spent fuel containment pool, you will actually measure the least radiation somewhere in the middle of the pool, thanks to shielding from the universe.
    - dan_hawkins 4y ago
      Spent Fuel Pool https://what-if.xkcd.com/29/ https://what-if.xkcd.com/29/
      - jvanderbot 4y ago
        Nice, thank you!
      - revicon 4y ago
        The last lines are the best... But just to be sure, I got in touch with a friend of mine who works at a research reactor, and asked him what he thought would happen to you if you tried to swim in their radiation containment pool. “In our reactor?” He thought about it for a moment. “You’d die pretty quickly, before reaching the water, from gunshot wounds.”
        wkat4242 4y ago
        I know someone who worked at a medical isotope reactor and there were no guns there, at least not in the reactor area. Security tends to be much much further outside ;) After all, remember some things in a reactor don't react well to bulletsch.

sanxiyn 4y ago

From Earth's hydrothermal vents, we know sunlight isn't necessary for life although energy is.

Mistletoe 4y ago
We don’t know if life started in the light though and then migrated to the vents and adapted. My memory of it is that this is an unanswered question so far.
- causality0 4y ago
  We know that life is older than photosynthesis. I'm not aware of another light-dependent metabolic process that could predate chemosynthesis.
- dcminter 4y ago
  It's definitely an open question. But in his book "The Vital Question", Nick Lane makes an interesting case that they're actually the origin of all life: https://nick-lane.net/books/the-vital-question-why-is-life-the-way-it-is/ https://nick-lane.net/books/the-vital-question-why-is-life-t...
peter303 4y ago
Its a good hypothesis that life start at deep volcanic vents. Geologist Robert Hazen conducted lab experiments showing that all steps of the metabolic citric cycle occur in this environment without needing catalytic enzymes. Chemical reduction of magma provides the energy. As life developed enzymes to improve metabolism, it could migrate to colder, lower pressure environments.

akiselev 4y ago

Tidal heating [1] [1] https://en.m.wikipedia.org/wiki/Tidal_heating https://en.m.wikipedia.org/wiki/Tidal_heating

Aardwolf 4y ago
Interesting stuff! Made me find that even rogue planets (free floating without orbiting any star) might theoretically be warm enough to support oceans and life: https://en.wikipedia.org/wiki/Rogue_planet#Warmth https://en.wikipedia.org/wiki/Rogue_planet#Warmth
- PaulHoule 4y ago
  Could be either tidal or geothermal. It’s been conjectured that even Pluto could have liquid water inside. The point is that generic small outer solar system bodies have liquid water, whereas the generic inner solar system body doesn’t. If you think liquid water is the most important requirement for life then most of the habitat in the universe is outside the frost line. It’s totally plausible that simple life could form around geothermal vents on such a moon but harder to believe you could support a complex ecosystem enough to evolve intelligent life without sunlight. At the high pressures in such an underground ocean I wouldn’t expect our proteins to work, you can kill bacteria with very high pressure. I suspect that proteins that evolved in that environment could work just fine. I can picture a creature from that kind of world drilling up to the surface somehow, but the low pressure would be deadly and in a system like Jupiter where Io ‘breeds’ radiation (vapor from volcanos gets ionized, gets accelerated, ionizes more vapor) the surface could be a dangerous place. Such a creature though might have a leg up on starfaring as getting into orbit might be easier (never mind building a beanstalk) and rather than being tempted by boring destinations like Mars (smaller planet, smaller civilization) they might go straight to cutting up wet/carbonaceous asteroids to build large (100-1000x more habitable area than Earth) habitats and if they developed D-D fusion they might be quicker to see the advantages of a comet-hopping lifestyle.
  - lumost 4y ago
    One of the Main limiters with underwater intelligent life would be industrialization. How are you going to use a steam engine underwater? What do you burn to heat it? Given that geothermal vents would be the source of life for such a species - capping them for machinery would also be unwise.

wkat4242 4y ago

It's also awash with radiation from Jupiter. If there's life, it won't be as we know it :)

zirgs 4y ago
Water is really good at radiation shielding.
- jvanderbot 4y ago
  I've heard that if you swim into a nuclear reactor spent fuel containment pool, you will actually measure the least radiation somewhere in the middle of the pool, thanks to shielding from the universe.
  - dan_hawkins 4y ago
    Spent Fuel Pool https://what-if.xkcd.com/29/ https://what-if.xkcd.com/29/
    - jvanderbot 4y ago
      Nice, thank you!
    - revicon 4y ago
      The last lines are the best... But just to be sure, I got in touch with a friend of mine who works at a research reactor, and asked him what he thought would happen to you if you tried to swim in their radiation containment pool. “In our reactor?” He thought about it for a moment. “You’d die pretty quickly, before reaching the water, from gunshot wounds.”
      - wkat4242 4y ago
        I know someone who worked at a medical isotope reactor and there were no guns there, at least not in the reactor area. Security tends to be much much further outside ;) After all, remember some things in a reactor don't react well to bulletsch.