Science fiction that takes its science seriously is rarer than it should be and better when it occurs. Kim Stanley Robinson's Mars trilogy is the best example I know — Red Mars, Green Mars, Blue Mars — which takes the science of terraforming as seriously as any non-fiction account, embeds it in a political argument about what humans do to environments they colonize, and sustains it across three long novels.

The first book, Red Mars, is the best. It introduces twelve colonists and uses their different relationships to Mars — as resource, as home, as symbol — to dramatize the political and ecological argument. Each colonist is a position in a debate, but they're also people, and the debates are embodied in relationships that develop over decades.

I recommend it to people who think science fiction can't be serious about science. It is the most technically rigorous novel I've read and also one of the most politically serious.