doi: 10.1371/journal.pbio.0020302. Epub 2004 Sep 14.
What is life--and how do we search for it in other worlds?
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- PMID:15367939
- PMCID: PMC516796
- DOI: 10.1371/journal.pbio.0020302
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What is life--and how do we search for it in other worlds?
Chris P McKay. PLoS Biol.2004 Sep.
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Abstract
If there is life on distant worlds, how would we go about finding it?
Figures
A Mars Global Surveyor image showing Nanedi Vallis in the Xanthe Terra region of Mars. The image covers an area 9.8 km ×18.5 km; the canyon is about 2.5 km wide. This image is the best evidence we have of liquid water anywhere outside the Earth. Photo credit: NASA/Malin Space Sciences.
Nonbiological processes produce smooth distributions of organic material, illustrated here by the curve. Biology, in contrast selects and uses only a few distinct molecules, shown here as spikes (e.g., the 20 l-amino acids on Earth). Analysis of a sample of organic material from Mars or Europa may indicate a biological origin if it shows such selectivity.
References
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- Connerney JEP, Acuna MH, Wasilewski P, Ness NF, Reme H, et al. Magnetic lineations in the ancient crust of Mars. Science. 1999;284:794–798. - PubMed
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