I am trying to find what would be a stable atmosphere for a planet, using this https://docs.google.com/spreadsheets/d/1cW7BIWlBUscqS9MVqs5gSbPH0OGzyE-j2cz6ADBSVzE/edit#gid=0 (you have to make a copy to use it, as editing is disabled for obvious reasons.)
It calculated the stability of an atmosphere of a certain compostion depending on the gravity of a planet (which it calculates from mass and radius, of course).
When I make the atmosphere of a planet at 0.7g, a large amount of elements become unstable. H, H2, He, N, O, CH4, NH3, H2O, and Ne become unstable. As compared to the H, H2, and He of it based on Earth's gravity. I tried to change values to find what would be stable, but I am having difficulty.
I am not sure what formulae it actually uses, so I am confused on how I would be able to find atmospheric stability at different gravities, with what percentages I should do for it. Because, from what I can find, a planet of 0.7g would be able to hold in such an atmosphere. I just can't find how exactly to find how I should adjust the percentages to make it such.
This isn't just about finding the way it works with this sheet, but just a general idea of how I would work to find what atmospheric composition is needed to retain stability at non-Earth gravities. Based on actual science. It is this latter part of the fact I am trying to find deeper knowledge of how to find stable atmospheric compositions that leads me to use Hard Science.