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We all know that Titan has an atmosphere that consists mainly of N2.

What I want to have is a planet with an atmosphere that consists mainly of various nitrogen oxides (NO, NO2, N2O).

My questions are:

  • What could lead to such a situation? Could such an atmosphere even develop?
  • Could the atmosphere be stable?
  • What would be a possible range for the surface temperature and density? It should be vaguely earthlike (T = -50 to +80 *C, Pressure = 0.1 to 3 atm).
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  • $\begingroup$ See Hal Clement's Nitrogen Fix. $\endgroup$ – JDługosz Jun 5 '16 at 10:19
  • $\begingroup$ I will add this book to my reading list, it sounds interesting. The "maturing" of an O2-N2 atmosphere into an N/NO atmosphere using bacteria is a good idea indeed. However, I want for nitrogen oxides, not N2 to be the main component of the atmosphere (Yes, you guessed it right, the astronauts will use special masks that separate NO, NO2 and N2O into N2 and O2 to create normal air.). $\endgroup$ – MedwedianPresident Jun 5 '16 at 11:58
  • $\begingroup$ Clement really knew chemestry, so choosing those particular constituents was probably well considered. To do as well, you need to talk to an organic chemist. why would metabolism produce those waste products, and how are they used by complementary organisms to maintain equilibrium rather than a runaway? $\endgroup$ – JDługosz Jun 5 '16 at 14:52
  • $\begingroup$ Alternatively, you could involve geologic inorganic processes for some parts of the cycle. $\endgroup$ – JDługosz Jun 5 '16 at 14:53
  • $\begingroup$ Could your atmosphere be made of NO, NNO, and NOO? I have no idea but the question itself might offer some hints. $\endgroup$ – Xandar The Zenon Jun 23 '16 at 23:25
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Lets start from the top...

Could it form naturally? Probably not.

Nitric Oxide (NO) is an unstable compound in its native form and, if exposed to any amount of Oxygen (including Ozone) it will steal an Oxygen atom to turn into Nitrogen Dioxide (NO2). The body of organic life on Earth produces NO, but it has a half-life of only a few seconds in blood before it can steal Oxygen to turn into NO2.

Nitrogen Dioxide (NO2) really isn't that much more stable than Nitric Oxide. The bond strength between the Oxygen and Nitrogen isn't very strong, and there is a free electron on the Nitrogen, making the whole compound a free radical. It reacts strongly with water, creating nitric acid...it is also highly reactive with alkalies and alchohols.

Nitrous Oxide (N2O), when exposed to oxygen, turns into Nitric Oxide, which (as discussed) then turns into Nitrogen Dioxide. So, ultimately, your atmosphere all wants to turn into NO2, which is still a very reactive compound.

Ultimately...your problem is this: Oxygen is very, very reactive, and Nitrogen forms weak bonds with it. All three of these compounds are strong oxidizers...meaning that they will freely give up their Oxygen atoms to many, many different compounds.

Moving on...will it be stable?

No.

Your entire atmosphere is made of oxidizers...any compound that likes to react with oxygen is going to snatch it up. Nitrogen, by itself (N2), is very much non-reactive...this is why our atmosphere is stable on Earth, because most of the atmosphere is made of a compound that is chemically boring. You do NOT want your atmosphere to be reactive...otherwise, it will react with anything and everything, and your atmosphere will either change composition dramatically...or will cease to be an atmosphere.

I would also like to add that anyone attempting to live on this planet, suspending disbelief such that it may exist, would essentially live in a giant powder keg. You are in an extremely oxygen rich environment. All of those 'no smoking anywhere near this' signs that you see on pure oxygen tanks? That applies to the whole planet. With such high oxygen concentrations that oxides make up the vast bulk of your planet's atmosphere: Iron Is flammable. It rusts so rapidly that it burns.

I suppose I can toss this out there, even though this planet is unlikely to exist (for long, anyway...even if you terraformed it that way on purpose). But, your average global temperature, assuming normal 1 bar pressures, needs to stay above 70.2 degrees F, because that's the boiling point for NO2.

TL;DR: Your desired planet's atmosphere is highly reactive. This is Bad.

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  • $\begingroup$ The astronauts can't do a BBQ then... $\endgroup$ – MedwedianPresident Jul 25 '16 at 19:20

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