re-invasion from the moon

terraforming earth by jack williamson is a post-apocalyptic scifi novel about an outpost on the moon that is set up to clone a set of humans who are then taught how to go about terraforming the earth after an apocalyptic event (an asteroid/comet strike).

but it takes a few different generations of clones to get it right, with some of the attempts failing due to various problems (aliens, another asteroid, stupid humans).

it’s a pretty good read, and a quick read. the ending is rather bland.