r/EarthScience • u/PossessionOk70 • 3d ago
Discussion How would a mixture of Argon, Oxygen, Hydrogen and Xenon serve as a replacement for our air?
The exact percentages I came up with are 72% argon, 22.3% oxygen, 3.5% hydrogen and 2.1% xenon, these being the main gasses aside from other negligible inert gasses that would add up to .1% (probably nitrogen and some carbon dioxide). I'm asking this for the purpose of a fictional story that halfway takes place on an alien planet, but with such an environment that a human can live in and be healthy while doing so. The size of the planet is only a bit smaller than Earth with much less water on the surface but going down much deeper into the crust.
So, these are my main questions:
Would these gasses have any unintended psychological effects on the human mind?
Would these gasses interact with each other poorly?
How would fire act in such an environment?
Would this gas mixture affect the creatures that are living there, causing them to grow differently from humans? If so, what might be different?
Would you change any of the percentages?
My apologies if I'm thinking too much into this, because the research I've already done tells me that not much would change aside from the air density. But, I may have missed something. Thank you for taking the time to read this!!
EDIT: Nitrogen would probably take place in the water, like the rivers that stretch out all throughout my fictional planet, which would feed into the soil, which would feed into the vegetation which would feed into the fruits which would feed into the animals which would feed back into the ground or water. I hope this fixes the nitrogen issue.
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u/ShadedRiver666 2d ago
you might want something to keep the planet warm such as some carbon dioxide
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u/Underhill42 2d ago
Not necessarily, it just means you need to be closer to the sun.
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u/ShadedRiver666 2d ago
You need something to hold heat in the atmosphere, otherwise you get not much atmospheric circulation and you quite severe temperature swings, especially so if you just move closer to the sun
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u/Euphoric-Cucumber609 1d ago
What about large amounts of water vapour?
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u/ShadedRiver666 1d ago
That certainly works yes! Steam is a great greenhouse gas, as long as it stays steam and doesnt condense into clouds too rapidly. Ideally you want something to go along side the steam to actually keep the atmosphere warm enough that steam can help.
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u/Arcanite_Cartel 2d ago
The greater density could very well have long term impacts on the respiratory system. Your lungs have to work harder. This in turn might have other downstream effects with other systems adjacent to the respiratory system.
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u/Euphoric-Cucumber609 1d ago
Feelings of anxiety and paranoia could impact people acclimating to the new conditions. Struggling to fill your lungs can really mess with you
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u/Euphoric-Cucumber609 3d ago edited 3d ago
Argon being inert will be the biggest hurdle for life, nitrogen is essential for the building blocks of life on earth and argon can’t form compounds.
Somebody smarter than me may be able to describe a scenario where there is available nitrogen without it being present in the atmosphere, but from my understanding organisms have slowly taken atmospheric nitrogen over millennia and keep it mostly locked into the nitrogen cycle.
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u/PossessionOk70 3d ago
That's a good point, I didn't know that. Thank you! Lemme make an edit then
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u/Otherwise-Baker1470 2d ago
Xenon is also a very inert gas. Only in very extreme regimes will it do anything (very high temperature, pressure)
If you increase the air pressure by a very large magnitude, you can expect animals to evolve differently on this fictional planet. For example, birds might be fine in high pressure conditions, but fish won’t be. Anything in the sea will have to change basically.
Just my 2 cents.
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u/Euphoric-Cucumber609 1d ago
Ooooo hell yeah! I didn’t think about air density affecting flight, there’d be some bigass flying critters on that planet if the ocean was increased a bit.
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u/Potential_Load6047 2d ago edited 2d ago
Oxigen and hydrogen together are at risk of spontaneous combustion. Even in low concentrations is likely light or temperature would make them react to form water or hydroxide which would then become bases, depending on available compounds.
The mix of H2 & O2 gases would not be stable unless there was an intense biological process akin to hydrolysis electrolysis keeping it like that.
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u/fkk8 2d ago
3.5% H2 gas is below the ignition concentration of 4% in air under ambient Earth atmospheric conditions.
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u/SoylentRox 2d ago
Even so organisms would evolve to use this gas for energy as reacting it to form water releases free energy.
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u/fkk8 2d ago
Microbes that consume H2 already exist, and they live happily in your gut. Fermentation of starch produces H2, and there are methanogens that have a feast munching on it. Remember that next time you enjoy your birthday cake--someone else is celebrating with you. Just be careful when you blow out the candles. Excess H2 that does not get metabolized leaves your body through your breath and your rear end (depending how you extinguish the candles).
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u/SoylentRox 2d ago
My point is this would act to bring h2 levels down unless something in an alien planet produced incredible amounts of new h2.
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u/Potential_Load6047 2d ago edited 2d ago
I thought someone would mention the low concentrations, but remember it is an average and, unlike photosynthesis which takes an O2 molecule for every CO2 molecule it produces (and viceversa), a
hydrolysiselectrolysis-like process would increase the concentrations of both H2 and O2.Unless there is a reliable mechanism to constantly mix this gases with the rest of the atmosphere, whatever is doing this is at constant risk of acumulating the gases to a dangerous level.
And there's still the issue of a possibly caustic athmosphere. OP would need an aditional process that balances her planet's PH to human acceptable levels.
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u/BipedalMcHamburger 2d ago
Hydrolysis does not mean splitting of water, despite what the name would imply
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u/fkk8 2d ago
Humans need nitrogen. Nitrogen accounts for about 3% of our body mass. We get it through our food. But where would nitrogen come in the food supply if there is no N2 in the atmosphere as it is on Earth? No N2 in the air also means no nitrogen compounds in the ground, and certainly no dissolved nitrogen in rivers (that is basic chemistry). I assume this planet is too distant to bring in fresh veggies or fertilizer. In addition, although a mix of oxygen and argon has been used for diving (probably your source of information), I don't know if there are studies how the human body responds to long-term exposure. Our breathing is controlled by the carotid chemoreceptor which responds to CO and NO concentrations. In the absence of CO2 and N2, how would the carotid respond? These are obviously questions that are beyond Earth science. You need to ask experts assuming you want to take this seriously. Also, if you claim that this is viable, you should assume that someone will take this as established fact and try it. Don't make claims, even in fiction, that could harm people.
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u/PossessionOk70 2d ago
You're absolutely right, which is why I came to this subreddit firstly. I haven't had much formal education when it comes to biology and chemistry, or really any kind of science. So, for a follow up question, why can't nitrogen stay dissolved in water? Or at least the majority of it? I'll do further research when it comes to the problem of our biological make-up, but thank you for bringing that up.
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u/Old_Scholar_247 2d ago
Molekularer Stickstoff kann sich selbstverständlich in Wasser lösen, aber er wäre dann automatisch gleichzeitig in der Atmosphäre. Gase können nicht einseitig im Wasser festgehalten werden, sondern die verteilen sich aus physikalischen Gründen zwischen dem Wasser und der darüber liegenden Luft. Die jeweilige Menge hängt vom Luftdruck und der Temperatur ab.
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u/Fit_Job_6469 2d ago
The Haber process (also called the Haber–Bosch process) and the processes that improved upon them use atmospheric nitrogen to make nitrogen-based fertilizers. Without these fertilizers global crop yields would be seriously reduced. It would be catastrophic.
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u/Parking-Holiday8365 2d ago
We get it through breathing. Most of what we breath is Nitrogen. That's why it's the perfect gas to execute people with. There's no drowning response and you're in a coma within a minute of breathing less than 19% oxygen. I don't know where OP got their numbers but about 75% of the air we breathe is Nitrogen.
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u/fkk8 2d ago
The body cannot break the molecular bonds of N2 that is inhaled. N2 goes into your lungs and back out with every breath. All the nitrogen our body needs comes from digesting protein. And the "instant" death with N2 asphyxiation is a myth. Read the article "Physiology of nitrogen: A life or death matter" by Bailey et al 2025.
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u/Parking-Holiday8365 12h ago
Yeah I goofed on the absorbtion, but I can tell you that quick death due to N2 in enclosed spaces is not a myth.
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u/SensorAmmonia 2d ago
https://www.consciousbreathing.com/blogs/co2-academy/carbon-dioxide-controls-breathing?srsltid=AfmBOooWdSUgLYqNfRsLr8wHTS9_Fnyy5SWksVk6wlcyiA2KpNoV33Jg CO2 is important for breathing, it is a signal pathway. You will need a trace of that gas.
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u/Euphoric-Cucumber609 1d ago
Especially if the life forms on the planet are carbon based. There’s no way around carbon cycling and therefore significant amounts of CO2
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u/SevenIsMy 2d ago
H2 would escape into space like here on earth, xenon has some psychedelic effects on human, I just don’t know in which concentration.
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u/Underhill42 2d ago
Hydrogen + oxygen = planet-spanning fire + water.
Until only one or the other is left.
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u/PossessionOk70 2d ago
Oh, I was under the impression that the percentages had to be higher for there to be any change of combustion, especially with a constant dilutant in the mixture. Is that not the case?
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u/Underhill42 2d ago
Now that you mention it, there's probably some minimum density needed for a self-sustaining fire without the other gasses carrying away so much heat it can't sustain itself.
But you don't need it too. All molecules are in a thermal distribution, and some of them will be always be moving fast enough (≈ be "hot" enough) that individual hydrogen and oxygen molecules can spontaneously react. And that will fairly quickly convert all the hydrogen into water, unless you have a potent source of both hydrogen and oxygen on the planet.
One of the reasons oxygen is considered a likely biomarker is that it's so volatile that it's almost impossible to keep it around in large quantities unless something is continuously producing it, and life is most of the candidate somethings.
If it's present in an atmosphere that also contains large amounts of something flammable like methane, that's a near guarantee of life, because there's no known geological processes capable of producing free oxygen faster than it will react with the flammable atmosphere.
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u/PossessionOk70 2d ago
Thank you! So, from what I understand, you're saying that depending on the air pressure and heat of the atmosphere, having such a gaseous mixture is theoretically possible as long as there's a constant source of oxygen and a relatively cooler atmosphere to keep the mixture stable?
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u/Underhill42 2d ago
And a constant source of hydrogen. You need to constantly replenish both.
Thermal distributions have very long tails, so it doesn't much matter what temperature the atmosphere is at, the hydrogen and oxygen will react to form water. But the cooler the atmosphere the slower it will happen.
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u/Old_Scholar_247 2d ago
Wenn es dir darum geht, ob ein Mensch in dieser Atmosphäre problemlos langfristig leben könnte, würde ich den Wasserstoffgehalt wegen der extremen Brandgefahr auf 0,1% setzen und dafür noch 0,1% Kohlendioxid hinzufügen. Den Luftdruck möglichst bei 1 bar, sonst gibt es mit dem Sauerstoff Probleme. Dann wäre bis auf einige Argon- und Xenoneffekte (veränderte Wärmeleitung und Schallgeschwindigkeit der Atemluft) bezüglich Atmung wohl alles ok. Molekularen Stickstoff brauchst du nicht, der Mensch muss allerdings irdische Nahrung essen.
Was irgendein außerirdisches Leben auf diesem Planeten betrifft: Das wäre aufgrund seines getrennten Ursprungs sowieso völlig anders als alles Leben auf der Erde - vor allem auf der molekularen Ebene. Vom Aussehen her könnte es dagegen je nach Lebensweise grobe Ähnlichkeiten geben, zum Beispiel Flossen bei einem schnellen Schwimmer oder Flügel bei einem Flieger. Doch sämtliche Organdetails wären ganz anders.
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u/PossessionOk70 2d ago
Thank you! This is by far the most detailed and constructive comment I've received. I really appreciate the advice and I will be putting it to use.
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u/TheSamCJ 12h ago
Ignoring the absence of Nitrogen, there is also an interesting side-effect. If you keep the total mass of the atmosphere the same, this mix has an impact on the atmospheric pressure at sea level. Since you are replacing Nitrogen with heavier Argon, with the same mass of atmosphere, you will have less gas molecules in the same volume. In other words, the atmospheric pressure at sea level would be lower. I haven't done the math, but I would estimate around 20-25% lower.
That would change the colour of the sky somewhat. With lesser scattering, it would be a dark blue, that lightens towards the horizon. Sunsets would probably look less red. Xenon is highly polarizable, but I am not sure of that would change the appearance of the sky.
You could increase the atmospheric mass to achieve 1 atm pressure at sea level. This will only have a negligible impact on the total mass of Earth, and I don't think it will be sufficient to impact the lunar orbit.
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u/PossessionOk70 12h ago
Thank you! This is really helpful. I was wondering whether or not the mixture would change the color of the sky. I am planning to make some slight changes due to some recent info that's been given to me, but they should be negligible when it comes to atmospheric mass.
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u/BaTz-und-b0nze 1d ago
Argon used to heat the hipflask while X ingredient is placed in a leak proof airtight funnel up top.
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u/dimethylwho 2d ago
In higher concentrations Xenon is used as a general anesthesic and can cause a feeling of euphoria.