My question is simple, could we "nuke" a planet with life to create an atmosphere over time?
I was seeing a documentary about Jupiter's moon, Europa, and how it could have hydro thermal microbial life because it is ideal for it, which made me think, could we produce any noticeable change on a celestial body's atmosphere if we send a large amount of bacteria or any kind of organism with the ability of producing oxygen? It seems evident that some earth's microorganisms can survive and reproduce in some planets and moons, I assume that the quantity would have to be massive (or maybe not if it can reproduce quickly) for it to produce enough oxygen to have any noticeable effect and it would be after many many years, but is that theoretically possible?