Would it be possible to construct an atmosphere condusive to human life on Venus (or some other planet)? Basically create a biosphere. Vanus is rich in CO2, right? So if we shipped in a bunch of plants to use the CO2 and generate O2, then that would shift the balance of O2. Then we could ship a bunch of animals there... I know it would be incredibly more complex and difficult than this simplistic view, but is it theoretically possible to germinate a planet and "create" a balance for life in such a way?