Concepts for detection of extraterrestrial life
NASA SP-56
CONCEPTS FOR
DETECTION OF
EXTRATERRESTRIAL LIFE
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
CONCEPTS FOR DETECTION OF
EXTRATERRESTRIAL LIFE
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Photograph of Mars obtained on August 24, 1956 (18 days before the opposition on September 11, 1956) by R. B. Leighton of the California Institute of Technology. The distance between Earth and Mars at the time the photograph was taken was about 35,000,000 miles. The Mt. Wilson 60-inch reflector was used with its aperture cut to 21 inches by an off-axis diaphragm. The exposure time, on Kodachrome Type A film, was 20 seconds. The positive, used in making the print, was composed by George Emmerson at the Jet Propulsion Laboratory.
This color photograph suggests that the darker areas of Mars are not necessarily “green” in color as they are often described, but may be a darker shade of the prevailing yellow-orange light areas. It is noted that the photograph as it appears here has been subjected to duplication in the course of which some minor color changes occurred. The brilliant white south polar cap is clearly evident. Rather surprisingly, this cap is probably just what it looks like—a thin layer of frozen water, perhaps in the form of hoarfrost. As the polar cap recedes, the dark areas (especially those in the same hemisphere) become darker. The dark area near the lower right-hand limb of Mars is Syrtis Major, one of the most prominent and well-known features of the planet. This feature, among others of its kind, has been of increasing interest to exobiologists in recent years. The extremely light-colored area to the right and just below the ice cap is Hellas, one of the most prominent Martian desert areas.
NASA SP-56
CONCEPTS FOR
DETECTION OF
EXTRATERRESTRIAL LIFE
Edited by
Dr. Freeman H. Quimby
Office of
Space Science
and Applications
Scientific and Technical Information Division 1964
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
Washington, D.C.
Acknowledgments
The editor wishes to express his appreciation for special technical and editorial assistance to: Dr. Klaus Biemann, Massachusetts Institute of Technology; Dr. Ira Blei, Melpar, Incorporated; Dr. Carl Bruch, National Aeronautics and Space Administration; George Hobby, Jet Propulsion Laboratory; Dr. Norman H. Horowitz, California Institute of Technology; Dr. Thomas Jukes, University of California; Dr. Elliott Levinthal, Stanford University Medical Center; Dr. Sol Nelson, Melpar, Incorporated; Dr. Carl Sagan, Smithsonian Astrophysical Observatory and Harvard College Observatory; Dr. Gerald Soffen, Jet Propulsion Laboratory; Dr. Wolf Vishniac, University of Rochester; and Dr. Robert Kay, Philco Research Laboratories.
The entire text has been reviewed by Drs. Horowitz and Sagan.
F.H.Q.
FOR SALE BY THE SUPERINTENDENT OF DOCUMENTS, U.S. GOVERNMENT PRINTING OFFICE, WASHINGTON, D.C., 20402—PRICE 50 CENTS
Preface
The principal objective of the search for life on another celestial body is to determine the state of chemical evolution if life has not yet arisen, or the state of biological evolution if life is present. A study of such life might contribute to a universal concept of the origin and nature of living systems. In addition, chemical and microscopic examination of any fossils from a pre-existing biota could provide equally valuable information.
This subject has provoked excessive speculation by some scientists, while others seem unaware of the implications of seriously confronting it. The quest for life in space rests on a reasonable degree of geological plausibility. A widely accepted theory argues that the known planets condensed under conditions compatible with the retention of water, ammonia and methane as gases in the primitive atmospheres. Laboratory experiments have demonstrated that primeval energy sources would have synthesized numerous biologically-significant molecules from these gases. Life developed on Earth when these gases and energies were also available to the other planets. Furthermore, it is both factual and perplexing that (except for helium) there is a closer resemblance between the elemental composition of living systems and the universe than there is between that of living systems and the rocky material in the terrestrial crust on and in which such systems are in intimate residence. Indeed, living matter on Earth displays a “unity of biochemistry” which may well be a principle with cosmic as well as terrestrial validity.
These arguments do not prove the hypothesis, but suggest that we cannot avoid the experiment. It is the purpose of this publication to describe briefly this experiment for the academic community and the public. Some of the methods which have been considered thus far for the detection of extraterrestrial life and life-related substances in the near reaches of space are presented.
Homer E. Newell,
Associate Administrator for
Space Science and Applications
Contents
CHAPTER PAGE 1 I. 7 II. 11 III. 13 IV. 17 V. 21 VI. 23 VII. 27 VIII. 31 IX. 35 X. 39 XI. 45 XII. 49 51 53
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