"Rich mix" methane/oxygen atmosphere on a planet -- how would life develop?

Let us assume we have a rocky planet by the name of Pyros orbiting a single star, the Star of Random. It has an atmosphere consisting of 77% methane, 21% oxygen, 1% water vapor, and 1% other gases (argon, CO2, NH3?), all at a surface pressure of 101kPa (one Earth atmosphere). Temperatures at the surface are sufficient for liquid water to exist despite Pyros' sun being dimmer and/or further away, as methane is an effective greenhouse gas. Furthermore, the atmosphere composition is apparently stable -- it's too rich to sustain combustion on a wide scale.

What adaptations would 1) photosynthetic and 2) chemoheterotrophic life have on this planet compared to similar categories of Earth organisms? Furthermore, how far could life develop on such a planet? Assume that the nitrogen cycle is primarily subterranean, supplemented by small amounts of atmospheric NH3.

posted almost 7 years ago

Shalvenay‭

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