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The Joshua Lederberg Papers

Launching a New Science: Exobiology and the Exploration of Space

[Joshua Lederberg in front of Mars Lander chart]. [1973].
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Joshua Lederberg spent the fall of 1957 as Fulbright Visiting Professor of Bacteriology in the laboratory of virologist Sir Frank MacFarlane Burnet at the University of Melbourne, taking part in the research on antibody production that would earn Burnet a share of the Nobel Prize in 1960. From his vantage point in Australia, Lederberg witnessed the ascent of Sputnik on October 4, 1957, the first man-made satellite in earth orbit. The launch of Sputnik by the Soviet Union intensified the Cold War, but it also heralded the age of space flight and exploration, with its promise of revealing new secrets about the nature of the universe and the origins of life.

Sputnik filled Lederberg with both excitement and apprehension: excitement about the potential of unmanned spacecraft as research tools; apprehension about man's likely impact on other planets. Upon his return to the University of Wisconsin in December 1957, he immersed himself in the literature on astronomy and rocketry in order to address his main concern: that other planets which might harbor life could be contaminated by microorganisms carried from earth via spacecraft, and that, conversely, earth could fall victim to an unknown pathogen brought back from another planet, a pathogen to which earth's inhabitants had no immunity (a scenario depicted in Michael Crichton's 1969 science fiction novel, The Andromeda Strain).

In letters to the National Academy of Sciences (NAS), to which he was elected the same year, Lederberg expressed his fear of such a "cosmic catastrophe" produced by interstellar contamination. His call for a strict protocol of sterilization, decontamination, and quarantine of both outgoing und returning spacecraft persuaded NAS president Detlev Bronk and his subsequent successor, Frederick Seitz (by coincidence, the two respectively preceded Lederberg as presidents of Rockefeller University), to put the issue before the Academy's council, which released an official statement of concern in February 1958.

In spring 1958, the Academy established the Space Science Board at the request of the U.S. National Committee for the International Geophysical Year. Lederberg was one of its founding members, and served on the board until it was dissolved in 1974. The board's mission was to assess the scientific aspects of space exploration, of interplanetary probes, manned spaceflight, and space stations, and to propose directions for science experiments and the search for life in space. It urged that "great care" be taken in sterilizing spacecraft before launch, and recommended a "stringent" quarantine for samples returned from other planets until it could be determined that they were harmless. The National Aeronautics and Space Administration (NASA) adopted both recommendations prior to its first flight to the moon in 1969.

Lederberg's urgent warnings about interstellar contamination, and his call for the scientific study of life beyond earth's atmosphere--for which he coined the term exobiology--tapped into popular fascination with the dawning of the space age, and brought him international media attention. "I was the only biologist at the time who seemed to take the idea of extraterrestrial exploration seriously," Lederberg remembered. "People were saying it would be a hundred years before we even got to the moon." He, however, "was convinced that once the first satellite was up the timetable would be very short, and [his] fear was that the space program would be pushed ahead for military and political reasons without regard for the scientific implications." He collaborated with the well-known astronomer Carl Sagan in establishing exobiology as a scientific discipline, and educated the public on the biological implications of space exploration in his weekly "Science and Man" columns in the Washington Post during the 1960s.

By publicly promoting exobiology, Lederberg almost single-handedly gained a place for biologists in the burgeoning U.S. space program, as well as a share of its ample research funds. He pressed upon NASA the need to include biological science in its mission and research designs, and represented the interests of biologists on the agency's Lunar and Planetary Missions Board between 1960 and 1977. In this role he helped define the scientific objectives for the Mariner Mars missions, launched between 1964 and 1971 to map the planet's surface and study its atmosphere from close-in orbits.

Lederberg participated directly in engineering experimental devices that were to decide mystifying and intriguing questions about the possibility of life on Mars. As principal investigator of the NASA-funded Instrumentation Research Laboratory at Stanford University Medical School from 1961 onward, he helped develop an automated biomedical laboratory that would allow scientists to examine the soil of Mars for traces of life as part of the Viking mission to the red planet in 1975. Like Sagan and the geneticist Herman J. Muller, Lederberg assumed that if life existed on Mars--which they considered quite possible--it must be in the form of microorganisms, because only they could withstand the planet's hostile environment and destructive radiation.

The device Lederberg designed with the help of the Instrumentation Research Laboratory's director, engineer Elliott Levinthal, consisted of a conveyer belt that scooped up samples of Martian soil and deposited them within a computer-controlled mass spectrometer. (An early version of the device was given the appropriately space-age name of "Multivator.") Inside the spectrometer the soil substance was bombarded with electrons, producing a fragmentation pattern which sorted the electrified particles (ions) according to their mass. This pattern was transmitted to earth, where scientists could analyze it for evidence of organic compounds and microbial life.

The data on microbial life on Mars produced by the Viking Mars Lander were inconclusive, and have since been discounted by further exploration of the planet's surface. Whether liquid water and, with it, life existed on Mars in the distant past remains an open question. Even so, the Mariner and Viking missions proved to Lederberg the effectiveness of automated space probes, robotics, and computers in acquiring valuable scientific data about space. By contrast, he regarded NASA's growing emphasis on returning man to space and preoccupation with the Space Shuttle during the second half of the 1970s as a threat to instrumented space flight and to the agency's scientific endeavors. After the launch of the twin Voyager probes to the outer solar system in 1976, NASA's last major instrumented mission for over a decade, Lederberg in 1977 ended his role as a consultant to the U.S. space program.