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In the opening weeks of 1998 a news article in the British journal Nature reported that NASA was about to enter biology in a big way. A "virtual" Astrobiology Institute was gearing up for business, and NASA administrator Dan Goldin told his external advisory council that he would like to see spending on the new institute eventually reach $100 million per year. "You just wait for the screaming from the physical scientists [when that happens]," Goldin was quoted as saying.1 Nevertheless, by the time of the second Astrobiology Science Conference in 2002, attended by seven hundred scientists from many disciplines, NASA spending on astrobiology had reached nearly half that amount and was growing at a steady pace. Under NASA leadership numerous institutions around the world applied the latest scientific techniques in the service of astrobiology's ambitious goal: the study of what NASA's 1996 Strategic Plan termed the "living universe." This goal embraced nothing less than an understanding of the origin, history, and distribution of life in the universe, including Earth. Astrobiology, conceived as a broad interdisciplinary research program, held the prospect of being the science for the twenty-first century which would unlock the secrets to some of the great questions of humanity.
It is no surprise that these age-old questions should continue into the twenty-first century. But that the effort should be spearheaded by NASA was not at all obvious to those--inside and outside the agency--who thought NASA's mission was human spaceflight, rather than science, especially biological science. NASA had, in fact, been involved for four decades in "exobiology," a field that embraced many of the same questions but which had stagnated after the 1976 Viking missions to Mars. In this volume we tell the colorful story of the rise of the discipline of exobiology, how and why it morphed into astrobiology at the end of the twentieth century, and why NASA was the engine for both the discipline's founding and for its transformation.
Why did NASA plunge into "extraterrestrial biology" and origin of life research very soon after its formation in 1958? By this time American popular culture had for decades demonstrated a peculiar fascination with life beyond Earth, particularly on the red planet Mars. Remnants of the canals of Mars controversy--a theory promulgated by the renegade American astronomer Percival Lowell, holding that Martians had built canals on their parched and dying planet--still echoed from a half-century earlier. Orson Welles's 1938 radio dramatization of The War of the Worlds, which people found so believable that it induced panic in the streets, was only twenty years in the past. The modern UFO craze was only a decade old, and science fiction stories such as Ray Bradbury's Martian Chronicles were part of popular culture. All of these elements greatly stimulated American popular interest in the possibility of life on other worlds, including among some who became NASA scientists. In a more technical sense already in 1938 the Soviet biochemist Alexander Oparin, in his influential book The Origin of Life, suggested modern biochemical scenarios, testable in a laboratory, to account for the origin of life on a primitive lifeless earth. Scenarios from Oparin's book formed the basis for the origin of life scenes in Disney's Fantasia and thereby spread through popular culture. Oparin's book also triggered a generation of researchers who began devising laboratory experiments to simulate the initial steps in the origin of life. In 1953 University of Chicago graduate student Stanley Miller convinced his skeptical advisor, geochemist Harold Urey, that they should undertake an experiment simulating conditions of a primitive Earth atmosphere; to the astonishment of the experimenters, and scientists around the world, within a few days the experiment succeeded in producing amino acids--the first steps toward life.
All this was in the background when NASA was formed. NASA made real the search for what had heretofore been science fiction scenarios of life on other planets and brought with this reality a host of practical problems. Scientists interested in the search for life immediately pointed out that space probes must be sterilized, lest earthly life brought by the spacecraft themselves contaminate the Moon and planets or mix with traces of life detected on these worlds. The reverse problem of back-contamination of the Earth by extraterrestrial microbial pathogens also loomed as a possible frightening consequence of space exploration. Hard-nosed engineers at NASA were skeptical, but forward-looking biologists had a different point of view. Not only did they take seriously the contamination possibilities; some also saw that the possibility of finding life or its building blocks in space or on other planets offered an unprecedented new way to observe the experiment of prebiotic chemistry which had been run repeatedly under different chemical conditions. With the advent of the means to explore space, the prospect of developing a truly universal science of biology now seemed possible for the first time.
Although at first NASA had to be convinced of this point of view, once convinced, the agency acted quickly to bring personnel and their research problems together into a fledgling program of extraterrestrial biology. This program was centered around designing actual spacecraft and instruments as well as developing the basic science necessary to search for life on other planets. At the same time, NASA undertook to determine the necessary conditions for the origin of life anywhere in the universe. Planetary science, extraterrestrial life, and origin of life research quickly became melded, in less than a decade, into an unprecedented new scientific discipline: exobiology. Researchers who had previously had little or no contact were suddenly thrown together, sometimes uneasily, because of the technical breakthroughs of the Space Age.
Who were these researchers, this first generation of exobiologists? They included the likes of Carl Sagan, a young astronomer at Harvard and later Cornell; Stanley Miller, the biochemist, fresh from his landmark experiment on the origin of life and already emphasizing its relevance to space research; and Joshua Lederberg, a young geneticist who received the Nobel Prize in the same year that NASA was formed. Three other biochemists were crucial to exobiology's early success: Melvin Calvin, soon-to-be Nobelist for his work on photosynthesis; Norman Horowitz, at CalTech, who brought a particular interest in Mars and a critical attitude toward Martian life; and Sidney Fox, whose laboratory was soon fueled by NASA funding for origin of life research. The goal of these scientists, among a growing number, was no less than a solution to the problem of the origin of life and where it might be found in the cosmos. In effect they began a process that would eventually produce a marriage between biology and astronomy, or at least certain parts of each discipline. As was the case for the manned lunar landing program, their vision of exobiology led to numerous spinoffs: technical breakthroughs, new insights in geology and astronomy, as well as some of the most important work in twentieth-century biology. Despite a deeply ambiguous role for biology within NASA, the exobiology program generated significant innovative ideas in biology, including Carl Woese's "three domain" classification for life, Lynn Margulis's heretical (but now widely accepted) endosymbiosis theory, and James Lovelock's Gaia hypothesis.
Despite its ambiguous role at NASA, the search for extraterrestrial life periodically became a driver for the American space program, exerting an influence that was disproportionate to its funding. From the beginning scientists and NASA administrators were fully aware of the enormous public relations potential of exobiology: they had grown up themselves enthralled by the promise of answering age-old questions about origins. Nothing short of putting men into space captivated public attention like searching for life on Mars. There was nothing more exotic, in all senses of the word, than the idea of extraterrestrial life or, most of all, extraterrestrial intelligence.2
Yet public relations is a double-edged sword. Almost immediately some biologists accused exobiology of being a science without a subject. How can one study extraterrestrial life when none is known to exist? they asked. (Never mind that those biologists had earthbound research programs and feared loss of funding if NASA poured large sums of money into exobiology programs, such as one billion dollars spent on the Viking missions to search for life on Mars.) Not that such opposition was completely surprising to the exobiology pioneers; they realized from the beginning the double-edged nature of the public relations aspect of their subject. Since 1947, when the UFO fascination began to grip American culture, any discussion of extraterrestrial life or intelligent life straddled a very thin line between respectable science and a search for "little green men." Nowhere was this more evident than in the cancellation of congressional funding for the Search for Extraterrestrial Intelligence (SETI) program in 1993, when it was targeted as a fanciful waste of money.
Controversial or not, exobiology was not about to disappear. Exobiologists explicitly claimed as their territory some of the most fundamental questions of humanity. What is life? How could one claim to recognize life or its beginnings without a clear-cut definition? Yet in 1960 this was just as much a matter of contentious debate as it had been in 1660. Indeed, the exobiologists themselves produced some of the most sharply conflicting ideas, especially while debating what kind of life-detection devices to send to Mars on the Viking mission. Has almost a half-century of exobiological research led to any greater consensus in the centuries-old debate over what life is? This book will answer that question. It goes without saying that origin of life research has been fundamentally transformed by its incorporation into exobiology, not least because it never had a big funding patron before NASA in 1960.
Exobiology has also given major impetus to planetary science, in particular the study of Mars and, more recently, the Jovian moon Europa. The claims of fossilized life in the Martian meteorite ALH84001 played an important role in the rebirth of exobiology as astrobiology, a role that we shall examine in detail. Similarly, exobiology gave major impetus to the search for planets around other stars, a search that has intensified with new techniques in astronomy. Why? Because planets are needed for life, and, especially since the American astronomer Frank Drake first proposed the mathematical likelihood of intelligent life on other worlds in 1960, one of the variables needed to refine that calculation is the fraction of stars that have planetary systems. The discovery of new planetary systems in the mid-1990s has given a strong new push to efforts to search for life, including intelligent life, on other planets. Despite the congressional cancellation of SETI program after less than a year of observations, SETI organizers quickly incorporated their work as a nonprofit group, the SETI Institute, and have continued largely with private donations. In their opinion the question was too important to be left to politicians.
Exobiology grew into a whole new scientific discipline by merging several previously quite disparate streams of research. Far from being a fluke or a short-lived creation that could only flourish under the relatively large infusion of money which NASA dispensed in the 1960s and 1970s for the Viking project, it has contributed significantly to viewing planetary scale processes such as global climate in a unified way. Exobiology actually favored interdisciplinary work that had great difficulty getting funded by the National Science Foundation (NSF) or the National Institutes of Health (NIH), the government agencies that fund most of the biological research in the United States. Since 1995 exobiology, under its new rubric of astrobiology, has expanded still further to embrace genomics, ecological research, and all science on the origin, history, and distribution of life in the universe. Today astrobiology remains a central driving force at NASA, a question of enduring popular interest, and one of the most important riddles of science. Given its fundamental questions, astrobiology is indeed here to stay.
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Notes
1. Tony Reichhardt, "NASA Lines Up for a Bigger Slice of the Biological Research Pie," Nature 391 (8 January 1998): 109.
2. Howard E. McCurdy, Space and the American Imagination (Washington, D.C.: Smithsonian Institution Press, 1997), chap. 5.