Orphans of the Sky (1941)

Robert Heinlein uses two long stories, "Universe" and "Common Sense," to think about one of the most difficult ethical problems of long-term space travel. If it's going to take multiple generations of time to get to another solar system, which is the best we can hope for from technology then and now still, that means the people setting out originally are the only ones with the choice of being there or not. Literature is full of stories of intergenerational conflict. Start with Oedipus—or Cain. That's probably not going to change just because you think you're on the adventure of a lifetime across the galaxy. That conflict is basically at the center of the two stories that make up Orphans of the Sky, with some ingenious twists. One is that, even though the original mission was intended to take only two or three generations at most, a mutiny, followed by religiously based ignorance, has left the sojourners believing the ship itself is the entirety of the universe. There is no anywhere else. It's a big ship but I'm sure you see the problem. Also, radiation has produced mutant strains who are ostracized and whose existence fuels a lot of the religious jingoism. Heinlein may be cynical but he's even more shrewd about human psychology. He gets away with the cynicism, in many ways like Mark Twain, because of the sunny disposition of his storytelling. Heinlein lives on a wonderful midcentury American attitude of can-do. His best characters are all about getting things done. This leads to various unbelievable points, such as the finish, but the well-scrubbed straight-shooter air nonetheless buoys it. I don't always agree with the main viewpoints in lots of Heinlein's work—he's way too militarist and capital-friendly for my tastes generally and the racial and sexual ideas can stray into the rancid. But it's easy to blame some of it on "the times" and rock along with his voice. Among other things he's about the work of imagining utopias, and his particular vision is one I can't help finding attractive, built on the urgency of our longing to know more and to explore. Heinlein obviously thought long and hard about the problems of multiple-generation space exploration. He's clearly not sure it's even feasible. But the resolve to do it is felt.

In case it's not at the library.