Earth's moon is a gray, lifeless place, interesting geologically but perhaps a little disappointing to those of us looking for strange, colorful new worlds. But our moon is only one of more than 60 planetary satellites in the solar system, most of which are entirely unexplored. In Moon Hunters (published in hardcover as Journey Beyond Selene), Jeffrey Kluger chronicles these unsung places and the heroes who explore them: the Jet Propulsion Lab's staff of dedicated adventurers, who build and fly sleek, unmanned spacecraft to investigate other moons. "When astronauts finally did reach the moon," Kluger writes, "the lean, fleet ships of the Jet Propulsion Laboratory had already gone elsewhere." Why explore the satellites of other planets when the planets themselves remain mysterious? Kluger describes astronomers' first realization that in contrast to the lifeless gas giant Jupiter, its moons were a veritable scientific playground: There were big moons and small moons, patterned moons and plain moons, brightly colored moons and pasty-pale moons.... There were moons that could have atmospheres, water, and even, perhaps, a spark of internal heat. Put them together, and you had moons that could, in theory, harbor life. Moon Hunters chronicles the history of a little-understood aspect of humanity's quest to discover new worlds. From the early Ranger orbiters through the incredible journeys of Voyager and Galileo, Kluger gives credit where credit is long overdue. They may not be astronauts, but these space jockeys have the right stuff. --Therese Littleton