Abstract
In its December 1990 fly-by of Earth, the Galileo spacecraft found evidence of abundant gaseous oxygen, a widely distributed surface pigment with a sharp absorption edge in the red part of the visible spectrum, and atmospheric methane in extreme thermodynamic disequilibrium; together, these are strongly suggestive of life on Earth. Moreover, the presence of narrow-band, pulsed, amplitude-modulated radio transmission seems uniquely attributable to intelligence. These observations constitute a control experiment for the search for extraterrestrial life by modern interplanetary spacecraft.
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References
Carlson, R. W. et al. Space Sci. Rev. 60, 457–502 (1992).
Hord, C. W. et al. Space Sci. Rev. 60, 503–530 (1992).
Belton, M. J. S. et al. Space Sci. Rev. 60, 413–455 (1992).
Gurnett, D. A. et al. Space Sci. Rev. 60, 341–355 (1992).
Lederberg, J. Nature 207, 9–13 (1965).
Lovelock, J. Nature 207, 568–570 (1965).
Lovelock, J. E. Proc. R. Soc. B189, 167–181 (1975).
Sagan, C. Proc. R. Soc. B189, 143–166 (1975).
Carlson, R. W., Arakelian, T. & Smythe, W. D. Antarct. J. U.S. (in the press).
Drossart, P. J. et al. Planet. Space Sci. (submitted).
Henderson, L. J. The Fitness of the Environment: An Inquiry into the Biological Significance of the Properties of Matter (Peter Smith, Gloucester, Mass., 1913).
von Zahn, U., Kumar, R. S., Neimann, H. & Prinn, R. in Venus Ch. 13 (eds Hunten, D. M., Colin, L., Donahue, T. M. & Moroz, V. I.) (Univ. of Arizona Press, Tucson, 1983).
Owen, T. in Mars Ch. 25 (eds Keiffer, H. H., Jakosky, B. M., Snyder, C. W. & Matthews, M. S.) (Univ. of Arizona Press, Tucson, 1992).
Walker, J. G. C. Evolution of the Atmosphere (Macmillan, New York, 1977).
Léger, A., Pirre, M. & Marceau, F. J. Astr. Astrophys. (in the press).
Lippincott, E. R., Eck, R. V., Dayhoff, M. O. & Sagan, C. Astrophys. J. 147, 753–764 (1967).
Chameides, W. L. & Davis, D. D. Chem. Engng. News 60, 38–52 (1992).
Hogan, K. B., Hoffman, J. S. & Thompson, A. M. Nature 354, 181–182 (1991).
Lewis, J. S. & Prinn, R. G. Planets and Their Atmospheres (Academic, New York, 1984).
Bowker, D. E., Davis, R. E., Myrick, D. L., Stacy, K. & Jones, W. T. Ref. Publ. No. 1139 (NASA, Washington, 1985).
Kilston, S. D., Drummond, R. R. & Sagan, C. Icarus 5, 79–98 (1966).
Sagan, C. & Wallace, D. Icarus 15, 515–554 (1971).
Sagan, C. et al. in Biology and the Exploration of Mars Ch. 9 (eds Pittendrigh, C. S., Vishniac, W. & Pearman, J. P. T.) (Natn. Acad. Sci. Washington, 1966).
Shklovskii, I. S. & Sagan, C. Intelligent Life in the Universe (Holden Day, San Francisco, 1966).
Sullivan, W. T., Brown, S. & Wetherill, C. Science 199, 377–388 (1978).
Chapman, S. Proc. phys. Soc. 43, 483–501 (1931).
Fainberg, J. & Stone, R. G. Space Sci. Rev. 16, 145–188 (1974).
Gurnett, D. A. J. geophys. Res. 79, 4227–4238 (1974).
LaBelle, J., Trumann, R. A., Boehm, M. H. & Gewecke, K. Radio Sci. 24, 725–737 (1989).
Keller, A. thesis, Univ. Iowa (1990).
Hines, C. O., Paghis, I., Hartz, T. R. & Fejer, J. A. Physics of the Earth's Upper Atmosphere (Prentice Hall, Englewood Cliffs, 1965).
Lederberg, J. & Sagan, C. Proc. Natn. Acad. Sci. U.S.A. 48, 1473–1475 (1962).
Gold, T. Proc. natn. Acad. Sci. USA. 89, 6045–6049 (1992).
Owen, T. in Strategies for the Search for Life in the Universe (ed. Papagiannis, M.) 177–185 (Reidel, Dordrecht, 1980).
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Sagan, C., Thompson, W., Carlson, R. et al. A search for life on Earth from the Galileo spacecraft. Nature 365, 715–721 (1993). https://doi.org/10.1038/365715a0
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DOI: https://doi.org/10.1038/365715a0
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