Signs of Life A Report Based on the April 2000 Workshop on Life Detection Techniques (2002) / Chapter Skim
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4 Detecting Extinct Life
4 Detecting Extinct Life
Pages 25-28
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From page 25... ...
Although it appears unlikely that evidence of fossil life can be obtained by orbital observations of an interesting site, the local environment may have preserved the ecological imprint of biological activity. Ecological signatures, possibly subtle and requiring broader spatial coverage for detection with rovers or networks of instruments, may be reflected among local rocks in chemical or mineralogical compositions or in gradients of these properties, as described in the paper by Fogel (see Session 3~.
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From page 26... ...
MOLECULAR AND ISOTOPIC METHODS FOR DETECTING EXTINCT LIFE Developments in the chemistry of natural products and organic geochemistry over the past decades have yielded molecular structural, isotopic, and stereochemical attributes that are common features in compounds of biological origin. These properties have been instrumental in establishing the antiquity of life on Earth and in tracking the early evolution of biological innovations in the geological record.
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From page 27... ...
In his paper in Session 4, Anbar argues that isotopic ratios of multiple elements beyond carbon, such as iron, could provide supporting and well-preserved indicators of past biological activities. In contrast to biosynthetic pathways, abiotic syntheses, as manifest in the organic chemistry of meteorites, yield distinctly different arrays of molecular structure across many compound classes.
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From page 28... ...
Although sedimentary rocks are arguably the most promising locations for preserving biosignatures, the fact that some terrestrial life forms exist on or in igneous rocks must also be recognized. Thus, hydrothermal systems associated with volcanic regions on Mars may be or may have been sites for life and, as noted above, must be on the list of potentially interesting sites for sampling.
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