Alien Atmospheres and Life For Scifi

[Spacescifi]

It is all too easy to make an earth clone with air like our own.

 

Just curious, supposing oxygen was part of the atmosphere, what other gas paired with it could support life as energetic as earth life besides nitrogen?

 

Pick a gas other than nitrogen.

 

Concentrations in whatever way will work, not necessrily earth oxygen/nitrogen ratios?

Oxygen/helium?

Oxygen/methane?

 

Anybody good with chemistry and biology?

Edited October 26, 2021 by Spacescifi

[TheSaint]

https://en.wikipedia.org/wiki/Hypothetical_types_of_biochemistry

[kerbiloid]

We are made of the cheapest junk in the Universe.

Why should they be better?

[TheSaint]

27 minutes ago, kerbiloid said:

We are made of the cheapest junk in the Universe.

Why should they be better?

Well, it's like Microsoft's unofficial corporate slogan: "Not better. Not worse. Just different."

[Codraroll]

5 hours ago, Shpaget said:

Well you certainly aren't. Come on dude, seriously? Put at least a bit of effort into these topics of yours.

Hey, an oxygen/methane atmosphere might work decently enough until a spark is ignited. From that point on, the planet might not be entirely conducive to life for very long, though.

[jimmymcgoochie]

Life can exist without any atmosphere whatsoever- right here on Earth there are chemosynthesis micro-organisms that live in rocks miles below the surface, slowly breaking down minerals for their energy and dividing every few decades or even centuries. Many organisms thrive despite a lack of oxygen and most of those would probably die if exposed to oxygen.

If you want complex, multicellular, intelligent life, nitrogen/ammonia could be an option with the ammonia replacing water as seen on Earth and also serving as a building block for this hypothetical organism’s biology. Another option is nitrogen/methane for much the same reasons, for example Saturn’s moon Titan.

Helium is too light to be a significant part of a planet’s atmosphere unless it’s significantly larger and/or colder than Earth- see gas giants- because it will just float up and out of the atmosphere; oxygen/methane is known generally as a gas explosion or fuel-air bomb, depending on who you ask, and would definitely NOT be stable for any length of time; carbon dioxide could work but the greenhouse effect would be significant and it’s also a waste product produced by carbon combustion/metabolism so is toxic to aerobic life in high quantities- even a few percent CO2 in pure oxygen can kill a human eventually; a case could be made for argon as a significant gas, it’s 1% of Earth’s atmosphere and could make up a lot more in a hypothetical atmosphere- up to a point, since it’s lighter than oxygen, nitrogen etc. Heavier noble gases like krypton and possibly xenon could also be included, but those are heavier than air and so would tend to sink, potentially smothering the surface.

It really depends on what sort of “life” you want- a tiny lichen-like thing clinging to a rock on a barren planet or a Pandora full of alien ecosystems, teeming with life in all its varieties. (Incidentally, I’ve heard it argued that Pandora was toxic due to high levels of hydrogen sulphide, a.k.a. rotting egg gas, presumably given off by the local wildlife.)

Edited October 26, 2021 by jimmymcgoochie

[kerbiloid]

Being allowed, humans can easily reproduce the Earth atmosphere on any planet.

_{The atmosphere of fear and mistrust.}

[linuxgurugamer]

3 hours ago, TommyJ said:

A habitable zone needs energy, carbon, liquid water, a list of chemical elements for light absorbing, energy and electrochemical reactions.

As we know life, yes.  But, consider that the earth is in a narrow band where liquid water exists along with the atmosphere, and lots of light.  So it makes sense that life which developed here would require those elements.

But now consider a planet where there is very little light, but huge amounts of radio energy, with a huge, complex atmosphere.  I am thinking about Jupiter.  We know very little about the planet compared to what we know here.  Eyes developed here because of the abundance of light, but what would happen in the absence of light and an abundance of radio energy? 

There are lots of stories which explore this type of genre.

[JoeSchmuckatelli]

Absent finding Unobtaniym (discovered by Russian Deep Spac3 Probe 7-with-slash), or frictionless abrasive powder or phlebotnium in abundant surface deposits - humans won't care about planets without Earth-analog atmosphere. 

Given that it's just chemistry and there are a lot of die to roll, pretty good chance that once the instawhere drive is available, so are the destinations. 

3 hours ago, Codraroll said:

Hey, an oxygen/methane atmosphere might work decently enough until a spark is ignited. From that point on, the planet might not be entirely conducive to life for very long, though.

The inhabitants did well, until that one guy took up smoking... 

[Terwin]

16 hours ago, Spacescifi said:

Concentrations in whatever way will work, not necessrily earth oxygen/nitrogen ratios?

Oxygen/helium?

Oxygen/methane?

Oxygen was originally a toxin/waste-product: https://en.wikipedia.org/wiki/Reducing_atmosphere

Nitrogen is not a relevant portion of the atmosphere for most organisms, it is just filler.  ('nitrogen fixing' organisms help to enrich the soil by taking it out of the atmosphere, but I am not aware of any other direct uses).  If anything, it helps provide more mass for radiation shielding, but anything could provide that.

 

 

 

[Spacescifi]

4 hours ago, Terwin said:

Oxygen was originally a toxin/waste-product: https://en.wikipedia.org/wiki/Reducing_atmosphere

Nitrogen is not a relevant portion of the atmosphere for most organisms, it is just filler.  ('nitrogen fixing' organisms help to enrich the soil by taking it out of the atmosphere, but I am not aware of any other direct uses).  If anything, it helps provide more mass for radiation shielding, but anything could provide that.

 

 

 

Nitrogen fixing in the soil is HUGE.

 

If it were oxygen/argon I wonder how plants and animals would react to that?

We could test it of course... not us but someone with funding and test subjects (insects and plants are an easy pick, go up from there) and see how they fare under an OX/AR atmosphere.

It seems that life is we know it, atmosphere included, is about as optimized as you can get.

 

Worldbuilding using realistic ingredients shows less than optimal results when using anything different from Earth's makeup.

 

My conclusion: If you want big  size creatures similar to ones found on Earth,  you are obliged to just copy Earth's makeup. Biology you can play around with a lot more though... so at least there's that freedom.

If you decide to change the atmosphere then you had better know what effects an argon oxygen atmosphere would have.

 

I may not know totally, but I reckon without nitrogen fixing in the soil the results may be bad. What? Argon fixing in the soil and organisms that mxke use of argon?

Edited October 26, 2021 by Spacescifi

[JoeSchmuckatelli]

1 hour ago, Spacescifi said:

If you decide to change the atmosphere then you had better know what effects

Over the last three decades, I've run into occasional articles about 'sunsets' or plant life on different worlds.  Scientific American stuff, rather than Popular Science - so you can at least have some comfort that there's been actual work done behind the article.  If you google enough, you should find some; I've seen 'plants will be black' under this light/atmosphere kind of articles.

Point being; you're not stuck just hoping an guessing - if you look hard enough, you will find some, if not fully on point, adjacent information by legit scientists.

[mikegarrison]

12 hours ago, linuxgurugamer said:

As we know life, yes.  But, consider that the earth is in a narrow band where liquid water exists along with the atmosphere, and lots of light.  So it makes sense that life which developed here would require those elements.

Exactly. This point seems missed so very often. Earth life is adapted to Earth conditions. Therefore we think Earth conditions are necessary for life. It would like if you thought desktop computers could only possibly be made to operate using AC power because all the ones we see plug in to AC outlets. But the computers were designed to work with the outlets, rather than the other way around.

What you need for life is basically a source of energy of some kind (probably a star) and some elements that can combine with some reasonable amount of complexity. I would suspect you also need some available liquid, because it's hard to imagine life developing without liquid-state chemistry. But who knows, maybe that's possible too.

Edited October 27, 2021 by mikegarrison

[FleshJeb]

3 hours ago, Spacescifi said:

Argon fixing in the soil and organisms that mxke use of argon?

"Before 1962, argon and the other noble gases were considered to be chemically inert and unable to form compounds; however, compounds of the heavier noble gases have since been synthesized. "

So, no.

Nitrogen is so useful because it's able to form a wide variety of compounds. It might be second only to carbon in the variety of chemical bonds it can readily form.

I highly suggest becoming familiar with why the Periodic Table is structured the way it is. It's probably the most elegant and useful data visualization ever produced by human beings. Hundreds of years of scientific inquiry summarized on one sheet of paper. I still remember how I FELT the day I figured it out, 30 years ago--It was quite an epiphany.

I'll even go so far as to say that you could show it to a scientist from another intelligent alien species, and they'd figure out what it represents pretty darn quick.

[kerbiloid]

9 hours ago, Terwin said:

Oxygen was originally a toxin/waste-product: https://en.wikipedia.org/wiki/Reducing_atmosphere

It's probably just a primordial simplistic explanation based on the lack of data, a folk theory of XIX.
https://ru-m-wikipedia-org.translate.goog/wiki/Кислородная_катастрофа?_x_tr_sl=ru&_x_tr_tl=en&_x_tr_hl=ru&_x_tr_pto=nui

It's very possible that actually the oxygen has accumulated due to changed composition of volcanic gases caused by the geological evolution.
The amount of oxidizable compounds reduced, the excess of the oxygen remained.

9 hours ago, Terwin said:

Nitrogen is not a relevant portion of the atmosphere for most organisms,

The nitrogen is critically important for most organisms at least because most of them dislike excessive concentration of oxygen. 

And because the active part of a life is proteins, and they contain a lot of nitrogen.

16 hours ago, linuxgurugamer said:

But now consider a planet where there is very little light, but huge amounts of radio energy

Passing through and not activating the chain of the biochemical reactions.

Only TV characters will live there virtually in TV trasmissions passing through.

3 hours ago, mikegarrison said:

It would like if you thought desktop computers could only possibly be made to operate using AC power because all the ones we see plug in to AC outlets.

The keyword is "power". AC or DC doesn't matter.

We have the powerest among the cheapest version of biochemistry, so any other exotic is so much less possible than unlikely deserves a notice.

[FleshJeb]

11 minutes ago, kerbiloid said:

Only TV characters will live there virtually in TV trasmissions passing through.

I'm going to do your job for you:

Spoiler

I propose we name this phenomenon, "Kerbiloid-posting"

[Piscator]

The "life as we know it" argument tends to be a bit overplayed in my opinion. With exactly one data point (and a still somewhat rudimentary knowledge of it), we simply can't tell if our kind of life is one of hundreds of wildly different arrangements or in fact the only type possible in this universe. While I don't consider the latter hugely likely, I would also guard against the "anything goes" approach. For every "hey, why not?" there's usually an "oh, that's why" and many of the ideas we consider plausible are simply a result of our lack of knowledge. (I'm looking at you, argon-fixating bacteria.)

That said, it seems like a safe bet to assume that nitrogen would play an important role in the biochemistry of extraterrestrial life (the number of elements that can "combine with some reasonable amount of complexity" is surprisingly limited). I disagree though, that this would require huge amounts of diatomic nitrogen in the atmosphere, which is an exceedingly hard molecule to utilize biologically. Since molecular nitrogen is a rather convenient end product of metabolic processes involving nitrogen species, I would expect at least some build-up in the atmosphere (which would in turn give organisms an incentive to develop nitrogen fixation), but I'm not sure this would need to result in more than trace gas levels. I might be pushing the analogy too far, but after all, carbon-fixating organisms get by with very little carbon dioxide in the atmosphere too.

[Spacescifi]

2 hours ago, Piscator said:

The "life as we know it" argument tends to be a bit overplayed in my opinion. With exactly one data point (and a still somewhat rudimentary knowledge of it), we simply can't tell if our kind of life is one of hundreds of wildly different arrangements or in fact the only type possible in this universe. While I don't consider the latter hugely likely, I would also guard against the "anything goes" approach. For every "hey, why not?" there's usually an "oh, that's why" and many of the ideas we consider plausible are simply a result of our lack of knowledge. (I'm looking at you, argon-fixating bacteria.)

That said, it seems like a safe bet to assume that nitrogen would play an important role in the biochemistry of extraterrestrial life (the number of elements that can "combine with some reasonable amount of complexity" is surprisingly limited). I disagree though, that this would require huge amounts of diatomic nitrogen in the atmosphere, which is an exceedingly hard molecule to utilize biologically. Since molecular nitrogen is a rather convenient end product of metabolic processes involving nitrogen species, I would expect at least some build-up in the atmosphere (which would in turn give organisms an incentive to develop nitrogen fixation), but I'm not sure this would need to result in more than trace gas levels. I might be pushing the analogy too far, but after all, carbon-fixating organisms get by with very little carbon dioxide in the atmosphere too.

 

A quick bit of google-fu revealed this about argon/oxygen atmosphere and plants:

Argon has no known biological role. However, bacteria in the nodules of certain plants like beans can absorb argon but cannot process further. Gardening and Landscaping Problems Associated with Argon (Ar) None known, good or bad.

So it's role is quite limited with life as we know it.

So for it to actually matter it would need to processed at the same levels as nitrogen.

 

Which causes a whole cascade of effects, since what is the byproduct of that processing? Somehow I reckon that it would be toxic.

Argon is VERY hard to react with anything or form compounds... yet scientists brute forced it using fluorine. Was unstablw though, since the atoms quickly left for the more familar nitrogen compound as soon as they were able. Who knows what it would take to make a stable argon compound?

 

So do you really want fluorine based life lol? Again... toxic for humans. You can forget interaction with PPE too.

https://www.science.org/content/article/argon-not-so-noble-after-all

 

 

 

Edited October 27, 2021 by Spacescifi

[kerbiloid]

2 hours ago, Piscator said:

Since molecular nitrogen is a rather convenient end product of metabolic processes involving nitrogen species

It's a product of the protostar ammonia buried underground and released.

It appears not because it's neededm but because it's a lot of it from the very beginning.

Much more than phosphorus.

[Piscator]

Getting argon to react is indeed very difficult. More importantly though, it's completely pointless in the first place. Argon has no known role in "life as we know it", because forming those exotic flourine compounds is basically all argon can chemically do. It's not that earth life is somehow uncreative or not trying hard enough, it's the fundamental properties of argon that make it useless in biochemistry.

[Spacescifi]

11 minutes ago, Piscator said:

Getting argon to react is indeed very difficult. More importantly though, it's completely pointless in the first place. Argon has no known role in "life as we know it", because forming those exotic flourine compounds is basically all argon can chemically do. It's not that earth life is somehow uncreative or not trying hard enough, it's the fundamental properties of argon that make it useless in biochemistry.

 

So we are back to life as we know it... not randomly configured, but as optimized as it possibly can be apparently.

Trying other configurations requires using it as a model, and changing the model from the ground up (atmosphere) appears rather nonproductive.

Edited October 27, 2021 by Spacescifi

[KSK]

5 hours ago, Spacescifi said:

So we are back to life as we know it... not randomly configured, but as optimized as it possibly can be apparently.

Trying other configurations requires using it as a model, and changing the model from the ground up (atmosphere) appears rather nonproductive.

No - we've merely eliminated one fanciful option (argon fixation). How you get from there to 'we're back at life as we know it', escapes me.

And as for life being as optimized as it can be - life is as optimized as it has to be and no more.  Take the human body for example.  Our eyes aren't as sharp as a hawk's, we don't have the sense of smell that a dog has, our hearing isn't anywhere near as acute as an owl's (which can hear a mouse heartbeat from some ludicrous distance away). Our senses evidently aren't as optimized as they could be but equally evidently, they've proven to be good enough.

Similarly, it's not hard to find downright poor design elements in human anatomy.

• The appendix.
• A combined eating and breathing system that can - and frequently does - go wrong, sometimes fatally so.
• Proximal (or even combined, in males) elimination and reproductive systems that can - and frequently does - lead to infections, particularly in females.
• For that matter, sticking the brain on the end of an obvious weak point like the neck isn't terribly optimized either. 

Evolution works with what it's got at the time and it doesn't work backwards.  It can produce some amazing things but it can also produce some horrible kludges. But if those kludges are good enough for the job (i.e. there's no selection pressure to get rid of them), they will tend to stick around.

 

Edited October 27, 2021 by KSK

[kerbiloid]

19 minutes ago, KSK said:

Proximal (or even combined, in males) elimination and reproductive systems that can - and frequently does - lead to infections, particularly in females.

As it's a all-in-one reptilian cloaca just torn out, the problem is the weak immune system which is a result of brain overсlocking.

You forgot to include the family souvenirs freely hanging outside in vulnerable position.
On the other hand, Darwin blesses this.

19 minutes ago, KSK said:

For that matter, sticking the brain on the end of an obvious weak point like the neck isn't terribly optimized either. 

It's on the same turret with all main sensors, to reduce the signal time.

Edited October 27, 2021 by kerbiloid

[JoeSchmuckatelli]

17 hours ago, mikegarrison said:

Earth life is adapted to Earth conditions.

That's one of the reasons I love the study of extremophiles.  This entire planet is infested with life; from the deepest oceans and caves to the thinnest parts of the atmosphere.

Panspermia seems entirely probable given the tenacity and ubiquity of life on this wet rock.

[Piscator]

In addition to what kerbiloid said, the appendix also seems to serve as a reservoir for gut microbes in case of ... severe discharge events.

As for the main point of the discussion, I wouldn't say that life as we know it is the only option (in reality as well as in fiction) but as long as we're talking about chemical life some similarities are probably inavoidable. The number of elements suitable for building macromolecules is severely limited, so I would expect other forms of life to use them roughly in the same way and for the same purposes we do. On the other hand, even among known life there is a huge amount of metabolical pathways that could be used as a basis for speculation. There's - as has been rightly pointed out - quite a lot of exotic stuff going on right under our noses.

 

In regard to the atmosphere first approach, it would probably have been a good first step to check what would make sense planetologically.

A methane/oxygen atmosphere would be chemically unstable (possibly even explosively so). Same would be true for ammonia, hydrogen sulfide, hydrogen(!) and carbon monoxide in combination with oxygen. Basically any highly reduced and highly oxidized compounds would tend to react with each other over time, making the atmosphere more or less unstable in the long run.

Large amount of noble gasses would also be tricky, since they are either quite rare in the universe or tend to get lost from the atmospheres of planets the size and position of earth due to their low molecular mass.

For the same reason, hydrogen compounds would likely be quite rare on an earth-like world, even in the absence of free oxygen in the atmosphere. Hydrogen - freed by photochemical reactions - would steadily get lost to space.

For a world comparable to our rocky planets, this leaves us basically with the classics: nitrogen, carbon dioxide and oxygen (if sufficiently replenished). It might get interesting again though, if we increase mass and/or the distance to the star.