[Loser]

Originally posted by Suicide Junkie:

quote:

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Maybe the pressure could be maintained at one earth atmosphere, with a mix of (say) 70% N2, ~26% O2, ~4% CO2.

That is dangerously close to a lethal atmosphere. Your colonists would suffer greatly, and casualties would be high.
Drop that CO2 concentration by at least an order or two of magnitude.

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One important thing to remmeber is that CO2 is heavy. It will collect at the ground, where your people are trying to breathe.

Also, it is a 'greenhouse gas'. Too much or too litte of certain gases at certain distances from stars producing certain levels of heat will lead to planets too hot or too cold for life.

CO2 levels need to be low. There needs to be some, but not much. Not much at all.