As humankind imagines living off-planet — on the moon, Mars and beyond — the question of how to sustain life revolves around the physical necessities of oxygen, food and water. We know there is water on the moon, but how do we find it? Is it in the craters? The shadowed regions? The poles? Knowing where to look gives astronauts the best chance at successfully living on the moon, something that has, heretofore, remained the stuff of science fiction. Researchers from the University of California San Diego may help bring science fiction to reality by providing a divining rod to guide future space missions, including NASA’s Artemis campaign, which seeks to explore and, eventually, inhabit the moon. Their work appears in a special issue of Proceedings of the National Academy of Sciences (PNAS) called “Water on the Moon and Mars,” which features Artemis I on its cover.