Astronomy and biology have been circling each other with timid infatuation since the first time a human thought about the possibility of other worlds and other suns. But the melding of the two into the modern field of astrobiology really began on Oct. 4, 1957, when a 23-inch aluminum sphere called Sputnik 1 lofted into low Earth orbit from the desert steppe of the Kazakh Republic. Over the following weeks its gently beeping radio signal heralded a new and very uncertain world. Three months later it came tumbling back through the atmosphere, and humanity’s small evolutionary bump was set on a trajectory never before seen in 4 billion years of terrestrial history.

At the time of the ascent of Sputnik, a 32-year-old American called Joshua Lederberg was working in Australia as a visiting professor at the University of Melbourne. Born in 1925 to immigrant parents in New Jersey, Lederberg was a prodigy. Quick-witted, generous, and with an incredible ability to retain information, he blazed through high school and was enrolled at Columbia University by the time he was 15. Earning a degree in zoology and moving on to medical studies, his research interests diverted him to Yale. There, at age 21, he helped research the nascent field of microbial genetics, with work on bacterial gene transfer that would later earn him a share of the 1958 Nobel Prize.1,2

Like the rest of the planet, Australia was transfixed by the Soviet launch; as much for the show of technological prowess as for the fact that a superpower was now also capable of easily lobbing thermonuclear warheads across continents. But, unlike the people around him, Lederberg’s thoughts were galvanized in a different direction. He immediately knew that another type of invisible wall had been breached, a wall that might be keeping even more deadly things at bay, as well as incredible scientific opportunities....