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NASA was founded to put American astronauts into space. But some scientists, led by Nobel Prize winner Joshua Lederberg, saw additional opportunities. In the weeks after Sputnik’s launch, Lederberg wrote memos to senior scientists around the country. A few months later he formalized those memos into an article for Science magazine.
Lederberg had seen Sputnik in the sky while on an academic trip in Australia. He was both exhilarated and frightened by what it portended for biology. Space had been breached. Much more would follow. Knowing a bit of history, he realized that humans had thoughtlessly contaminated every place they had visited on Earth. Now humans would soon be traveling to moons and planets.
“Since the sending of rockets to crash on the moon’s surface is within the grasp of present technique, while the retrieval of samples is not,” he wrote in Science, “we are in the awkward situation of being able to spoil certain possibilities for scientific investigation for a considerable interval before we can constructively realize them.”
As Lederberg and other scientists saw it, this was humanity’s first chance to look for life, or even for pre-life chemistry, beyond Earth. That meant, first, that spacecraft had to be sterilized in order to not contaminate samples with their own waste. Second, it meant figuring out what to look for. Water, carbon, other basic chemicals? What would life look like if it were just getting started? What would it look like where there were few resources?
NASA had been created with distinctly political and military ambitions. But scientists like Lederberg worked hard to insert science—in particular, origin-of-life research—into the agency’s mission and make it a civilian program. Ultimately, NASA appointed a 40-year-old biologist, Richard S. Young, to lead a program devoted to exobiology: a term coined by Lederberg to refer to scientific work on extraterrestrial life.
It was clear to Young that exobiology didn’t fit comfortably within the traditional biology of institutions such as the National Science Foundation and the National Institutes of Health. So he assembled the first generation of exobiologists by recruiting people from diverse backgrounds, including Lederberg, Margulis, and a University of Illinois professor, Carl Woese.
When Margulis arrived at graduate school, the University of Wisconsin had just built a huge electron microscope, among the most powerful in the world. Through it, she could see things that had previously been invisible. Most notably, she observed tiny structures called mitochondria. There can be hundreds, even thousands, inside each cell in a complex organism, and their function is to convert food into energy.
Looking into the microscope, Margulis seized on an idea that had been floated much earlier but had never gained much currency: that these mitochondria—found in the cells of complex organisms, from humans and horses to honeybees—were remnants of once free-living bacteria. Even more important, the origin of eukaryotic cells—of all the “higher organisms”—had come with the merging, somewhere back in evolutionary history, of two simpler single-celled organisms. This symbiosis had created a new, more complex creature altogether. Margulis was soon on the path to showing how central that merger was—not just to individuals, but to evolution as a whole. After all, in this scenario, evolution occurred not gradually but through a big, sudden change.