We are at the cusp of a golden age in space science, as increasingly more entrepreneurs-Elon Musk, Richard Branson, Jeff Bezos-are seduced by the commercial potential of human access to space. But Beyond Earth does not offer another wide-eyed technology fantasy: instead, it is grounded not only in the human capacity for invention and the appeal of adventure, but also in the bureaucratic, political, and scientific realities that present obstacles to space travel-realities that have hampered NASA’s efforts ever since the Challenger disaster.

In Beyond Earth, the authors offer groundbreaking research and argue persuasively that not Mars, but Titan-a moon of Saturn with a nitrogen atmosphere, a weather cycle, and an inexhaustible supply of cheap energy-offers the most realistic, and thrilling, prospect of life without support from Earth.