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.
If humans were about to travel in space, we were also about to spread terrestrial organisms to other planets, and conceivably bring alien pathogens back to Earth. As Lederberg saw it, either we were poised to destroy indigenous life-forms across our solar system, or ourselves. Neither was an acceptable option.
When he returned to the United States he quickly threw himself into learning all he could about astronomy and rocketry, and began writing urgent letters to the National Academy of Sciences, alerting his colleagues to the imminent danger.
We were poised to destroy indigenous life-forms across our solar system.
By the spring of 1958, Lederberg’s warning of a “cosmic catastrophe” was starting to make people sit up and pay attention. But this pot-stirring wasn’t just about scaring researchers and policy makers. It also marked the birth of a new type of science that could take place outside the usual bounds of the planet. In his own words, “I was the only biologist at the time who seemed to take the idea of extraterrestrial exploration seriously.”
His considerable reputation didn’t hurt, and in the following years Lederberg managed to place biological investigations squarely on a fledgling NASA’s agenda, coining a new term along the way, “exobiology”—the study of life beyond the Earth.
Exobiology profoundly influenced the way space exploration was conducted. Strict protocols were developed for the sterilization of spacecraft, and for quarantines to restrict what they might bring back. NASA built clean rooms, and technicians swabbed and baked equipment before sealing it up for launch.
Scientists got to work and hurriedly computed the acceptable risks for biological contamination of other worlds. One of the standards developed stated that a mission must present no more than a 1 in 10,000 chance of disrupting an alien ecosystem, a somewhat arbitrary choice that perhaps says more about our tolerance for messing up planets than anything else.
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