Methane Biosphere Differences
- Thread starter kilemall
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Just saw a science vid mentioning that methane is a low entropy molecule in an oxygen-nitrogen mix. Perhaps internal oxygen cycles cracking methane via photosynthesis?
kilemall
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Ya definitely a big question is the energy available.
One thing I saw was an article speculating that when Earth was methane pre- oxygenation, that plants were basically huge fungi.
http://www.spacedaily.com/reports/Fungi_made_life_on_Earth_possible_researchers_claim_999.html
Bacteria exists that uses methane, not sure it scales up.
https://en.wikipedia.org/wiki/Methanotroph
I have the following methane-cycle in my notes (that I think came from a TML post back in the late-90s) though I can't vouch for the feasibility:
Asimov suggested plants could use an analog of photoshythesis to split water into H and O, react the O with CH4 to form carbohydrates, and release H2 to the atmosphere. H2 breathing animals could eat the plants for the carbohydrates and exhale methane and water vapor. Such a process would lead to an atmosphere consisting largely of H2, NH4 and CH4.
Asimov suggested plants could use an analog of photoshythesis to split water into H and O, react the O with CH4 to form carbohydrates, and release H2 to the atmosphere. H2 breathing animals could eat the plants for the carbohydrates and exhale methane and water vapor. Such a process would lead to an atmosphere consisting largely of H2, NH4 and CH4.
Works well enough for me. Kilemall's link states that the known methanotrophs on Earth are also prokaryotes. Didn't Drye and Rancke present a prokaryote descended biopshere in G:Traveller -Sword Worlds? If so, could there be some ideas there?
H2 requires pretty large worlds to be retained. H2 in the atmosphere will RAPIDLY leak out into space. For H2 to be retained, you need to be roughly size 11 (18 Mm diameter at 1 D(earth)), Deuterium D2, Size 10, for T2 Size 8. (Converted from the MMWR tables in 2300).
The hydrogen cycle is going to result in a LOT of loss, and a lot of oxide waste, unless it' chemically or molecularly bound into something else.
I think the underlying idea behind that quote was that this would be an "H abundant" planet so we have H off-gassing going on.
In any event, seeing this in a super earth or sub-Jovian is probably right. Also, density tends to rise with planet size (up to a point) so that helps make this plausible too on an Earth+ sized planet.
But as I wrote at the outset, I can't really vouch strongly one way or the other - this stuff ain't in my domain.
In any event, seeing this in a super earth or sub-Jovian is probably right. Also, density tends to rise with planet size (up to a point) so that helps make this plausible too on an Earth+ sized planet.
But as I wrote at the outset, I can't really vouch strongly one way or the other - this stuff ain't in my domain.
If it is H2 abundant, then it would be classified as an Insidious Atmosphere, as H2 can bleed thru seals and even diffuse thru metal.
kilemall
SOC-14 5K
Of course the payoff of figuring this out is to have Big Methane Hunters and colonial problems. We can probably count on fairly safe interactions re: diseases, but of course any bite is going to be an immediate poisonous atmosphere problem.
Another fun thing to think about with atmospheres is the economic differences and opportunities, beyond just the life support ones.
The nature of the various rocks will be different as we wouldn't have any of the oxides/quartzes etc but we would have minerals that would be altered especially depending on the other atmospheric rocks, perhaps yielding different mining opportunities.
Chemical engineering would still use water, but oxygen would be in short supply- perhaps its cheap to burn the methane for heat, or other combos not available to a nitro/oxy world would make a colony worthwhile econoically.
Another fun thing to think about with atmospheres is the economic differences and opportunities, beyond just the life support ones.
The nature of the various rocks will be different as we wouldn't have any of the oxides/quartzes etc but we would have minerals that would be altered especially depending on the other atmospheric rocks, perhaps yielding different mining opportunities.
Chemical engineering would still use water, but oxygen would be in short supply- perhaps its cheap to burn the methane for heat, or other combos not available to a nitro/oxy world would make a colony worthwhile econoically.
Clarke briefly mentions something like that in Imperial Earth.
The protagonist is from Titan where the economy is based on selling hydrogen fuel. It's less hazardous to get it on Titan than Jupiter or Saturn not to mention the much smaller gravity well. He travels to Earth to represent Titan at the ceremonies for the US' 500 anniversary and speaks at a DAR meeting. During the speech, he draws parallels between the historical American frontier and the current Titan frontier. Paraphrasing the passage, he mentions that instead of adding fuel to a fire surrounded by oxygen as American pioneers did, the people on Titan add oxygen to a fire surrounded by fuel.
kilemall
SOC-14 5K
I was thinking of using that basic animal size formula to help adjust animals for this environment, but really you've got to know what the basic cycle pressure is going to be to figure out energy available to the animal.
Come to think of it, we sort of have an adjustment with the atmosphere factor re: air pressure/thickness.
Come to think of it, we sort of have an adjustment with the atmosphere factor re: air pressure/thickness.
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