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Life Detection on the Early EarthFinding evidence for first the existence, and then the nature of life on the early Earth or early Mars requires both the recognition of subtle biosignatures and the elimination of false positives. The history of the search for fossils in increasingly older Precambrian strata illustrates these difficulties very clearly, and new observational and theoretical approaches are both needed and being developed. At the microscopic level of investigation, three-dimensional morphological characterization coupled with in situ chemical (isotopic, elemental, structural) analysis is the desirable first step. Geological context is paramount, as has been demonstrated by the controversies over AH84001, the Greenland graphites, and the Apex chert microfossils . At larger scales, the nature of sedimentary bedforms and the structures they display becomes crucial, and here the methods of condensed matter physics prove most useful in discriminating between biological and non-biological constructions. Ultimately, a combination of geochemical, morphological, and contextural evidence may be required for certain life detection on the early Earth or elsewhere.
Document ID
20040191783
Acquisition Source
Headquarters
Document Type
Conference Paper
Authors
Runnegar, B.
(NASA Ames Research Center Moffett Field, CA, United States)
Date Acquired
August 22, 2013
Publication Date
January 1, 2004
Publication Information
Publication: Second Conference on Early Mars: Geologic, Hydrologic, and Climatic Evolution and the Implications for Life
Subject Category
Life Sciences (General)
Distribution Limits
Public
Copyright
Public Use Permitted.

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