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I'm trying to design an artificial microbe that could survive in the crust of icy moons and dwarf planets in the outer solar system, such as Pluto and Triton. I'm thinking of making them hydrogen-consuming methanogens, and basing them off azotosomes, artifical cells created out of nitrogen, hydrogen and carbon, with a liquid methane solvent. Technically speaking, all the necessary ingredients are there, locked within nitrogen ice, water ice and carbon dioxide ice, but of course the difficulty is in accessing them. They're frozen solid for one thing, but even then, separating hydrogen from H20 is notoriously energy intensive, and you'd probably end up with a net energy loss. How can I get around this?

The only thing that's come to mind is the possibility of radiolysis, but other than eking trace radioactive elements out of the ice from ancient meteor impacts, I can't figure out how to generate that kind of radioactivity, and that's probably far too inefficient. This is intended to be an artificial species seeded by advanced precursors, btw, so it doesn't matter if any solutions are unlikely to have evolved naturally.

Can anyone help me with this?

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    $\begingroup$ First, we need to get the basic chemistry right. If photosynthesis is not an option, what would be the energy source for this life forms? $\endgroup$
    – Alexander
    Sep 16, 2020 at 17:49
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    $\begingroup$ have you heard of tardigrades? en.wikipedia.org/wiki/Tardigrade $\endgroup$
    – Topcode
    Sep 16, 2020 at 18:23
  • $\begingroup$ @Alexander My understanding is that methanogens exist buried under kilometres of ice in Greenland without any sunlight, and the methanogenic reaction could serve as the principal energy source? Quoting from wikipedia: 'Some of the CO2 reacts with the hydrogen to produce methane, which creates an electrochemical gradient across the cell membrane, used to generate ATP through chemiosmosis' $\endgroup$
    – Hubwubbub
    Sep 16, 2020 at 21:45
  • $\begingroup$ @topcode tardigrades cant really function in extreme conditions though, they can just temporarily endure them. $\endgroup$
    – Hubwubbub
    Sep 16, 2020 at 21:46
  • $\begingroup$ @Hubwubbub fine, but we we have to think in terms of compounds, not just elements. For methanogenesis, free hydrogen must be coming from somewhere, your microbes can't both produce and consume it. $\endgroup$
    – Alexander
    Sep 16, 2020 at 23:02

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An example species may be Endolithic Lichen. Endolithic Lichen actually live inside solid rock, existing in the pores or mineral grains (not cracks mind you but microscopic grains in the rock). They can also get all their energy from rock and not require sunlight (look at the Survival section of the wikipedia link). In this article Endolithic Lichen is investigated at the McMurdo station in Antarctica. The article also includes a scanning electron microscope image of the cells living in sandstone pores. The authors mention:

In light of these observations, the possibility of finding extraterrestrial endolithic communities on Mars cannot be eliminated.

They would be robust enough to survive extreme temperatures, and capable of living in solid rock (and solid ice I imagine as well).

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