Joshua Lederberg, a prominent member of the first generation of exobiologists and a leading light in the fields of exobiology/astrobiology and planetary protection, died February 2, 2008, at age 82. Rockefeller University, where Lederberg served as president emeritus, reported that the cause of his death was pneumonia.

As early as 1957, Lederberg was communicating with members of the scientific community about his concerns that space exploration, if not conducted with care, could contaminate extraterrestrial environments and interfere with the search for evidence of exrtraterrestrial life. Lederberg quickly became a key player in the field of what is now called planetary proection, as well as in the field of exobiology (now astrobiology).

In 1958, the year that NASA was formed, Lederberg, at age 33, won the Nobel Prize in Physiology or Medicine for his discovery that bacteria can exchange genes. Also that year, Lederberg coauthored an article for Science making the case for studying moondust as a “record of cosmic history” that might yield information about “the biochemical origins of life” and also taking steps to prevent contaminating the Moon and other extraterrestrial environments with terrestrial biology: “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, 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.”

While the international scientific community has since concluded that the Moon is devoid of life, Lederberg’s concerns are relevant to the exploration of Mars and other planetary bodies that might be hospitable to life.

In 1960, Lederberg presented a paper on exobiology to the 1st International Space Science Symposium, sponsored by the international Committee on Space Research (COSPAR), in Nice, France. Later that year, Science published an article by Lederberg, “Exobiology: experimental approaches to life beyond Earth,” based on his COSPAR talk. (The article was later published in the report of the Space Science Board of the National Research Council, “Science in Space.”) “Exobiology,” Lederberg concluded in this article, “is no more fantastic than the realization of space travel itself, and we have a grave responsibility to explore its implications for science and for human welfare with our best scientific insights and knowledge.”

Lederberg, who is credited with coining the term “exobiology,” was one of the first beneficiaries of NASA’s Exobiology Program, established in 1960. He received funding to develop a “Multivator,” a device for conducting biochemical analyses of soil samples. Lederberg served as a member of the Biology Team for NASA’s Viking mission to Mars.

In a 1963 letter to Science (Vol. 142, 1126), November 29), Lederberg addressed the broad scientific importance of exobiology and planetary protection:

“Several sources have privately suggested a new journal on ‘exobiology,’ the study of extraterrestrial life. My profound objections are not to their optimism; but the field is too important to be sequestered. The policy issues of interplanetary quarantine and of
large-scale expenditures in scientific programs deserve the widest critical attention; so do scientific questions that range from the origin of life to the extraction of interstellar signals from cosmic noise.”

In 1968, Lederberg coauthored a paper for Science with Carol Sagan and Elliott Levinthal arguing that NASA’s Viking spacecraft should be subject to stringent sterilization standards, toward ensuring against terrestrial biological contamination of the martian environment. He also coauthored later papers in Science on results of NASA’s Mariner 9 reconnaissance mission to Mars and the Viking Mars landers, among many other topics.

Though best known as a geneticist, Lederberg continued his involvement with the space science community throughout his career. Members of the planetary protection community have said he will be missed.


William J. Broad. Joshua Lederberg, 82, Nobel winner, dies. New York Times, February 5, 2008).

Steven J. Dick and James E. Strick. The living universe: NASA and the development of astrobiology. New Brunswick, NJ: Rutgers University Press, 2004.

Joshua Lederberg. Exobiology: approaches to life beyond the Earth. Science 132, 393-400, August 12, 1960.

Joshua Lederberg and Dean B. Cowie. Moondust: the study of this covering layer by space vehicles may offer clues to the biochemical origin of life. Science 127, 1473-1475, June 27, 1958.

Carl Sagan, Elliott C. Levinthal, and Joshua Lederberg. Contamination of Mars. Science 159, 1191-1196, March 15, 1968.