My spec-bio project involves the idea of life evolving on a (Carbon?) Planet, rich with metals (Platinum, Chromium, Etc...) and pre-existing hydrocarbons. Basically life would have to evolve on an already "polluted" planet.

It is a 7 planet system orbiting a G1.5 star. In the early stages of system development planetary drift occurred bringing one of the gas giants to the innermost orbit. The main habitable world was spared from annihilation but was bombarded with enough material from the asteroid belt to balance out the elements allowing for an "Early Earth" like atmosphere and liquid water to collect. (Is this within the realm of possibility?)

Being that a gas giant is so close (~1 AU away) the homeworld experiences a lot of gravitational flux, causing an increase in volcanism and outgassing. This is my explanation for the availability of metals, and partly the composition of the atmosphere.

Through no particular reason I've decided on an atmospheric content of

  • N2 ~68.4
  • O2 ~ 21.3%
  • CO2 ~ 3.25%
  • N2O ~ 3%
  • SO2 ~ 2%
  • Ar ~ .98%
  • Ne ~ 1.02%

Given that levels could replenished and maintained. Is there any other reason why this would not be a stable atmosphere?

Feel free to ask any questions if I left out any helpful information. I apologize for any apparent ignorance, i'm not a chemist or astronomer by any means.

Thank you to any and all who reply!

  • $\begingroup$ I'm very uncertain what you mean by a pseudo-carbon or carbon planet, can you clarify. $\endgroup$ Aug 4, 2022 at 7:10
  • $\begingroup$ @AngryMuppet Sorry, editing mistake. By Carbon Planet I mean a planet with a much higher carbon content than Earth. Enough for the formation of readily available hydrocarbons. I was just unsure of what else to call such a planet. $\endgroup$ Aug 4, 2022 at 7:31

1 Answer 1


Consider the following points.

  • Atmosphere is stable if production and consumption of gases is balanced.
  • On your planet, there is liquid water, which means that there will be rain. Rain dissolves CO2 and SO2 causing acid rain. The water bodies will become acidic reducing the percentage of SO2 and CO2.
  • No vegetation on the planet because of acid rains so no new production of O2.
  • No animals because (1) they will reduce the oxygen (2) they will faint by N2O (3) SO2 is very toxic and can cause death (4) No food because no vegetation.
  • Ninety-nine percent of the volcanic gases are water vapor (H2O), CO2, and SO2.

Atmosphere not stable

  • Oxygen will react with other substances and there is no production of oxygen so percentage of oxygen will reduce.

  • Percentage of CO2 and SO2 will be more where there is more volcanic activity and less where there is rain.


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