Even within the most speculative reaches of science fiction, there is no such thing as a escaping humanity’s dependence on liquid water. Luke Skywalker, the hero of the unique “Star Wars” trilogy, grows up on his uncle’s moisture farm, extracting water from Tatooine’s arid ambiance. The residents of the desert world Arrakis, accessible to anybody with a duplicate of Frank Herbert’s novel “Dune” (or with three hours to kill at their nearest cinema), likewise use windtraps to steal treasured liquid from the air.
