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Session 24 - HAD II.
Oral session, Monday, January 13
Over the last century, three eras may be distinguished in the quest for Martian life: 1) the search for intelligence, initiated by Percival Lowell in connection with the canals of Mars, and peaking with the 1909 opposition of Mars; 2) the visual and spectroscopic search for vegetation, from the 1920s to the 1960s; and 3) the spacecraft search for microorganisms and organic molecules, culminating with the apparently negative findings of the Viking experiments in 1976. To these three eras a fourth has now been added with the announcement on August 7, 1996 of the discovery of possible fossilized primitive life on Mars.
The evidence, in the form of organic molecules, possibly biogenic minerals and biological structures in an Antarctic meteorite believed to be of Martian origin, is still controversial. Such controversy is typical in the history of science, especially in the extraterrestrial life debate. In perhaps the most direct analogue, the 1960s claim of fossilized algae in carbonaceous meteorites proved to be terrestrial contamination. The outcome of the current controversy may be quite different.
Quite aside from the spectacular nature of the claims, the search for Martian life is compelling for the history of science because it is a case study of science functioning at its limits. Moreover, Mars is seen as a test case for the widespread existence of life in the universe. At stake is a world view, which has now become testable, and which we may term the "biophysical cosmology". Unlike physical cosmologies, it proposes that life is an essential property of the universe, the final outcome of cosmic evolution. The recent discoveries of planetary systems lend credence to this world view. The history of the entire debate is elaborated in Steven J. Dick, The Biological Universe: The Twentieth Century Extraterrestrial Life Debate and the Limits of Science (Cambridge University Press, 1996).
Program listing for Monday