After reading Kim Stanley Robinson's essay "Our Generation Ships Will Sink", I'm reminded that — although the Mars books are wonderful and I love them — Aurora may be his most crucial. It is the only space-faring science fiction book I know of that fully grapples with the perils that would bedevil any interplanetary voyage, making the reader viscerally aware: there is no planet B.
If you carry some naive faith that we can somehow science our way out of these problems if only we dream big enough, I invite you to roll up your sleeves and get the fuck to work proving it before you gamble with the only sure home we have.
I love science fiction (space opera especially) and always will. But I don't give a damn about trying to move into space (even in our solar system) until we figure out how to take care of each other and this planet we already have.