Here on Earth, we've found organisms that thrive in environmental conditions we would have once thought uninhabitable. The presence of these extremophiles suggests that life could potentially take hold on worlds other than our own.
It goes back to the starfish. That's when the light bulb really popped over my head. We'd found one on the beach, and I was struck by what astonishing creatures they are, talking with Dad about how they regenerate.
For a genre that's about looking to the future, science fiction has sure been looking backwards lately. Nostalgia is what sells best, with readers spending their money on movie tie-in novels and sequels to long-running series.