Let's create an alien biosphere!
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Let's create an alien biosphere!
I just finished watching the existing episodes of Biblaridion's series on speculative evolution on an alien planet, and I kind of wanted to do it myself, so here's the thread dedicated to it. I would like the planet to be a terrestrial super-Earth, though super-Earth means any planet whose mass is in between 1-10 Earth masses, so I'm leaving it up to others to determine exactly how heavy this planet will be. Please don't forget that gravity does not scale up linearly with planetary mass. This planet will also have no abiotic oxygen, all oxygen will come from cyanobacteria analogues.
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Re: Let's create an alien biosphere!
We probably want atmospheric oxygen eventually in order for land-based lifeforms to have protection from ultraviolet light. I'd like the atmosphere to have some methane or ethane, but I'm concerning about that, combined with the oxygen, making it vulnerable to combusting.
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Re: Let's create an alien biosphere!
I was already thinking of having methane in the atmosphere. This planet can hold a denser atmosphere as well because of its higher gravity.MathAndCode wrote: ↑January 5th, 2021, 12:57 pmWe probably want atmospheric oxygen eventually in order for land-based lifeforms to have protection from ultraviolet light. I'd like the atmosphere to have some methane or ethane, but I'm concerning about that, combined with the oxygen, making it vulnerable to combusting.
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Re: Let's create an alien biosphere!
Schiaparelliorbust wrote: ↑January 5th, 2021, 1:08 pmI was already thinking of having methane in the atmosphere. This planet can hold a denser atmosphere as well because of its higher gravity.
I guess that we can't put a lot of hydrocarbons in the air, then. The explosive limit might be a little higher if the atmosphere doesn't have as much oxygen, but I would expect that the denser atmosphere would at least cancel that out. I want to do something different, though. What if we increase the atmospheric concentration of ammonia? Then maybe plants could find a way to get nitrogen directly from the air instead of having to rely on bacteria.the Wikipedia page about methane wrote:As a gas it is flammable over a range of concentrations (5.4–17%) in air at standard pressure.
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Re: Let's create an alien biosphere!
5-10% methane is also explosive. Ammonia is also basic and corrosive, but I bet that the creatures on this planet can find a way around that. Let's keep the concentration low like <5%. Let's still have some methane though.MathAndCode wrote: ↑January 5th, 2021, 1:15 pmI guess that we can't put a lot of hydrocarbons in the air, then. The explosive limit might be a little higher if the atmosphere doesn't have as much oxygen, but I would expect that the denser atmosphere would at least cancel that out. I want to do something different, though. What if we increase the atmospheric concentration of ammonia? Then maybe plants could find a way to get nitrogen directly from the air instead of having to rely on bacteria.the Wikipedia page about methane wrote:As a gas it is flammable over a range of concentrations (5.4–17%) in air at standard pressure.
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Re: Let's create an alien biosphere!
Yes, since they could become used to the alkalinity, and could simply develop external layers for which ammonia is not corrosive.Schiaparelliorbust wrote: ↑January 5th, 2021, 1:28 pmAmmonia is also basic and corrosive, but I bet that the creatures on this planet can find a way around that.
How about 1.2% methane and 0.4% ethane?
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Re: Let's create an alien biosphere!
Actually I don't think there should be much methane unless there's some biological process that can get rid of it. Pre-industrial age methane concentrations are around 670-690 ppb and is a very potent greenhouse gas. It is 84 times more potent than CO2. We could also have high CO2 concentrations as well at first. Oxygen would probably be lethal at first anyway. It would oxidise organic molecules before they could form life probably.MathAndCode wrote: ↑January 5th, 2021, 1:49 pmYes, since they could become used to the alkalinity, and could simply develop external layers for which ammonia is not corrosive.How about 1.2% methane and 0.4% ethane?
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Re: Let's create an alien biosphere!
We could put the planet farther from its sun in order to compensate, but life probably would develop some process that consumes it, so it's probably best to not have a lot to begin with.Schiaparelliorbust wrote: ↑January 5th, 2021, 1:58 pmActually I don't think there should be much methane unless there's some biological process that can get rid of it. Pre-industrial age methane concentrations are around 670-690 ppb and is a very potent greenhouse gas. It is 84 times more potent than CO2. We could also have high CO2 concentrations as well at first. Oxygen would probably be lethal at first anyway. It would oxidise organic molecules before they could form life probably.
Yes, but the organisms are going to need to get energy through redox reactions, so they will need to have access to some oxidant. Carbon dioxide has carbon in the +4 oxidation state, but its three-center four-electron bonds make it too stable for reactions that consume it to provide much energy. Isocyanic acid can act as an oxidizing agent, and it has a positive enthalpy of formation, but the latter fact means that it will not form naturally in large quantities. (Otherwise, it could form from ammonia reacting with carbon dioxide.) Another possibility is for organisms to store oxidizing agents and collect reducing agents from the environment as needed. This would be the opposite of what animals and plants do on Earth, but there is no reason why it couldn't work. Possible options for this include isocyanic acid, nitrogen oxides/oxyanions, and sulfur oxides/oxyanions.Schiaparelliorbust wrote: ↑January 5th, 2021, 1:58 pmOxygen would probably be lethal at first anyway. It would oxidise organic molecules before they could form life probably.
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Re: Let's create an alien biosphere!
Yes, let's not put it too far. "Bacteria" can survive much higher temperatures, so keeping the planet cool a the start won't be a big priority.MathAndCode wrote: ↑January 5th, 2021, 2:26 pmWe could put the planet farther from its sun in order to compensate, but life probably would develop some process that consumes it, so it's probably best to not have a lot to begin with.
Before oxygen, bacteria used sulfur as an oxidant. There was even something something called the Great Oxidation Event, which killed most bacteria. Of those that died, sulfur-reducing bacteria now only live at places with low oxygen levels like the ocean depths. Maybe they could be like that? Also, if these creatures can find a way to store oxygen, they would have to find some way of preventing it from diffusing or controlling when it can diffuse. I don't really see it happening at bacterial scales because diffusion happens, AFAIR, at sizes smaller than 1mm.MathAndCode wrote: ↑January 5th, 2021, 2:26 pmYes, but the organisms are going to need to get energy through redox reactions, so they will need to have access to some oxidant. Carbon dioxide has carbon in the +4 oxidation state, but its three-center four-electron bonds make it too stable for reactions that consume it to provide much energy. Isocyanic acid can act as an oxidizing agent, and it has a positive enthalpy of formation, but the latter fact means that it will not form naturally in large quantities. (Otherwise, it could form from ammonia reacting with carbon dioxide.) Another possibility is for organisms to store oxidizing agents and collect reducing agents from the environment as needed. This would be the opposite of what animals and plants do on Earth, but there is no reason why it couldn't work. Possible options for this include isocyanic acid, nitrogen oxides/oxyanions, and sulfur oxides/oxyanions.
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Re: Let's create an alien biosphere!
Actually, there are many chemosynthetic organisms on the bottom of the ocean floor (on this planet) that require many forms or hydrocarbons for cellular respiration. It could be entirely plausible that organisms could exist in an atmosphere of hydrocarbons and be able to breath it.MathAndCode wrote: ↑January 5th, 2021, 1:49 pmYes, since they could become used to the alkalinity, and could simply develop external layers for which ammonia is not corrosive.Schiaparelliorbust wrote: ↑January 5th, 2021, 1:28 pmAmmonia is also basic and corrosive, but I bet that the creatures on this planet can find a way around that.How about 1.2% methane and 0.4% ethane?
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Re: Let's create an alien biosphere!
Yes, but that's deep in the ocean. In the atmosphere, it becomes explosive. Even a single spark would be disastrous.HelicopterCat3 wrote: ↑January 6th, 2021, 10:03 amActually, there are many chemosynthetic organisms on the bottom of the ocean floor (on this planet) that require many forms or hydrocarbons for cellular respiration. It could be entirely plausible that organisms could exist in an atmosphere of hydrocarbons and be able to breath it.
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Re: Let's create an alien biosphere!
Oh yeah. Oxygen. Pressure. Fundamental gas physics. Forgot about those...Schiaparelliorbust wrote: ↑January 6th, 2021, 10:07 amYes, but that's deep in the ocean. In the atmosphere, it becomes explosive. Even a single spark would be disastrous.HelicopterCat3 wrote: ↑January 6th, 2021, 10:03 amActually, there are many chemosynthetic organisms on the bottom of the ocean floor (on this planet) that require many forms or hydrocarbons for cellular respiration. It could be entirely plausible that organisms could exist in an atmosphere of hydrocarbons and be able to breath it.
I suppose I have another question, would organisms be able to develop in other liquid environments other than water is they have the correct materials solutes in them (since water is the universal solvent it makes it easy for life to develop in it but I'm asking if other liquids could work in a similar, but with less evolutionary possibilities)
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Re: Let's create an alien biosphere!
I will come back later in about an hour. I have to go now. I will edit this post with my reply.HelicopterCat3 wrote: ↑January 6th, 2021, 10:12 amOh yeah. Oxygen. Pressure. Fundamental gas physics. Forgot about those...
I suppose I have another question, would organisms be able to develop in other liquid environments other than water is they have the correct materials solutes in them (since water is the universal solvent it makes it easy for life to develop in it but I'm asking if other liquids could work in a similar, but with less evolutionary possibilities)
Edit: There are two problems with this:
1)I don't know of any substances that are liquid at room temperature that can occur abiotically in very large amounts. If there are any, please tell me.
2) We don't really know how life can function in non-water liquids. In Biblaridion's series, he said that you shouldn't break the rules without knowing them, and we don't really know the rules of creatures that could live in an environment like this.
Last edited by Schiaparelliorbust on January 6th, 2021, 11:39 am, edited 1 time in total.
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Re: Let's create an alien biosphere!
Since ammonia and carbon dioxide in the atmosphere have already been pitched, formamide could be an interesting solvent.HelicopterCat3 wrote: ↑January 6th, 2021, 10:12 amOh yeah. Oxygen. Pressure. Fundamental gas physics. Forgot about those...
I suppose I have another question, would organisms be able to develop in other liquid environments other than water is they have the correct materials solutes in them (since water is the universal solvent it makes it easy for life to develop in it but I'm asking if other liquids could work in a similar, but with less evolutionary possibilities)
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Re: Let's create an alien biosphere!
An atmosphere of CO2 and NH4 and oceans of formamide? Sounds neat.Kazyan wrote: ↑January 6th, 2021, 10:36 amSince ammonia and carbon dioxide in the atmosphere have already been pitched, formamide could be an interesting solvent.HelicopterCat3 wrote: ↑January 6th, 2021, 10:12 amOh yeah. Oxygen. Pressure. Fundamental gas physics. Forgot about those...
I suppose I have another question, would organisms be able to develop in other liquid environments other than water is they have the correct materials solutes in them (since water is the universal solvent it makes it easy for life to develop in it but I'm asking if other liquids could work in a similar, but with less evolutionary possibilities)
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Re: Let's create an alien biosphere!
I edited my above post.HelicopterCat3 wrote: ↑January 6th, 2021, 11:17 amAn atmosphere of CO2 and NH4 and oceans of formamide? Sounds neat.
How would that much formamide even be there in the first place? Also, we don't know anything about life in something like formamide, as I said in my edit.
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Re: Let's create an alien biosphere!
Here is a preliminary atmosphere based on what users have asked for directly (e.g. ammonia) or implied (e.g. water vapor because the planet has oceans). Feel free to suggest tweaks/changes.
50% dinitrogen
15% carbon dioxide
15% ammonia
6% sulfur oxides
5% carbon monoxide (in order for formamide to form)
2% dioxygen
1.5% methane
1% water vapor
1% hydrogen sulfide
0.6% ethane
0.4% isocyanic acid
2.5% other
50% dinitrogen
15% carbon dioxide
15% ammonia
6% sulfur oxides
5% carbon monoxide (in order for formamide to form)
2% dioxygen
1.5% methane
1% water vapor
1% hydrogen sulfide
0.6% ethane
0.4% isocyanic acid
2.5% other
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Re: Let's create an alien biosphere!
I think there should be no oxygen at all at first. In your atmosphere, since there's carbon monoxide it would bond with it anyway creating CO2. What would formamide do when in water? Also, how heavy will this planet be?MathAndCode wrote: ↑January 6th, 2021, 12:13 pmHere is a preliminary atmosphere based on what users have asked for directly (e.g. ammonia) or implied (e.g. water vapor because the planet has oceans). Feel free to suggest tweaks/changes.
50% dinitrogen
15% carbon dioxide
15% ammonia
5% sulfur oxides
5% carbon monoxide (in order for formamide to form)
2% dioxygen
2% hydrogen sulfide
1.5% methane
1% water vapor
0.6% ethane
0.4% isocyanic acid
2.5% other
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Re: Let's create an alien biosphere!
Yes, I had thought of the fact that dioxygen is typically formed by living organisms and that this atmosphere is supposed to be before life and had been meaning to clarify it with you.Schiaparelliorbust wrote: ↑January 6th, 2021, 12:21 pmI think there should be no oxygen at all at first.
Formamide and water are miscible, i.e. they can dissolve each other in any proportion.
Maybe it should have 20% more surface gravity than Earth?
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Re: Let's create an alien biosphere!
Perhaps a ratio of formamide to water could allow for interesting aquatic life. 20% more surface gravity would probably mean that the creatures would evolve with a much different (probably stronger and more supportive) bone structure than beings on Earth.MathAndCode wrote: ↑January 6th, 2021, 12:40 pmYes, I had thought of the fact that dioxygen is typically formed by living organisms and that this atmosphere is supposed to be before life and had been meaning to clarify it with you.Schiaparelliorbust wrote: ↑January 6th, 2021, 12:21 pmI think there should be no oxygen at all at first.Formamide and water are miscible, i.e. they can dissolve each other in any proportion.Maybe it should have 20% more surface gravity than Earth?
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Re: Let's create an alien biosphere!
I know that, I should have specified. Is there anything else they do together?MathAndCode wrote: ↑January 6th, 2021, 12:40 pmFormamide and water are miscible, i.e. they can dissolve each other in any proportion.
Ok, that sounds good.MathAndCode wrote: ↑January 6th, 2021, 12:40 pmMaybe it should have 20% more surface gravity than Earth?
Yes, they would have more muscle and bone mass and would be smaller than Earth creatures.HelicopterCat3 wrote: ↑January 6th, 2021, 12:45 pmPerhaps a ratio of formamide to water could allow for interesting aquatic life. 20% more surface gravity would probably mean that the creatures would evolve with a much different (probably stronger and more supportive) bone structure than beings on Earth.
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Re: Let's create an alien biosphere!
They could react to form ammonia and formic acid. Also, if certain oxides are present, which could happen as minerals in rocks on the seafloor, then they can cause formamide to split into water and hydrogen cyanide.Schiaparelliorbust wrote: ↑January 6th, 2021, 1:00 pmI know that, I should have specified. Is there anything else they do together?
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Re: Let's create an alien biosphere!
Umm hydrogen cyanide? Is there any way to get around this? Because I don't think even the creatures on this planet will tolerate it. Formic acid might be okay at low concentrations. It's a strong acid (pH 2.3).MathAndCode wrote: ↑January 6th, 2021, 1:41 pmThey could react to form ammonia and formic acid. Also, if certain oxides are present, which could happen as minerals in rocks on the seafloor, then they can cause formamide to split into water and hydrogen cyanide.
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Re: Let's create an alien biosphere!
They can simply evolve to tolerate it and even use it to their advantage. It can be useful as a building block for other biomolecules, and it can serve as an electron acceptor/oxidizing agent in certain contexts, which could be used to help drive exergonic reactions to power biological processes.Schiaparelliorbust wrote: ↑January 6th, 2021, 2:16 pmUmm hydrogen cyanide? Is there any way to get around this? Because I don't think even the creatures on this planet will tolerate it. Formic acid might be okay at low concentrations. It's a strong acid (pH 2.3).
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Re: Let's create an alien biosphere!
MathAndCode wrote: ↑January 6th, 2021, 2:32 pmThey can simply evolve to tolerate it and even use it to their advantage. It can be useful as a building block for other biomolecules, and it can serve as an electron acceptor/oxidizing agent in certain contexts, which could be used to help drive exergonic reactions to power biological processes.
Would this apply to creatures there or is there some way to prevent it or similar things from happening?The toxicity of cyanide is linked mainly to the cessation of aerobic cell metabolism. Cyanide reversibly binds to the ferric ions cytochrome oxidase three within the mitochondria. This effectively halts cellular respiration by blocking the reduction of oxygen to water.
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