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atmospheric energy for subsurface life on mars?The location and density of biologically useful energy sources on Mars will limit the biomass, spatial distribution, and organism size of any biota. Subsurface Martian organisms could be supplied with a large energy flux from the oxidation of photochemically produced atmospheric H(2) and CO diffusing into the regolith. However, surface abundance measurements of these gases demonstrate that no more than a few percent of this available flux is actually being consumed, suggesting that biological activity driven by atmospheric H(2) and CO is limited in the top few hundred meters of the subsurface. This is significant because the available but unused energy is extremely large: for organisms at 30-m depth, it is 2,000 times previous estimates of hydrothermal and chemical weathering energy and far exceeds the energy derivable from other atmospheric gases. This also implies that the apparent scarcity of life on Mars is not attributable to lack of energy. Instead, the availability of liquid water may be a more important factor limiting biological activity because the photochemical energy flux can only penetrate to 100- to 1,000-m depth, where most H(2)O is probably frozen. Because both atmospheric and Viking lander soil data provide little evidence for biological activity, the detection of short-lived trace gases will probably be a better indicator of any extant Martian life.
Document ID
20040141684
Document Type
Reprint (Version printed in journal)
External Source(s)
Authors
Weiss, B. P.
(California Institute of Technology MS 150-21, Pasadena, CA 91125, United States)
Yung, Y. L.
Nealson, K. H.
Date Acquired
August 22, 2013
Publication Date
February 15, 2000
Publication Information
Publication: Proceedings of the National Academy of Sciences of the United States of America
Volume: 97
Issue: 4
ISSN: 0027-8424
Subject Category
Exobiology
Distribution Limits
Public
Copyright
Other
Keywords
NASA Center JPL
NASA Discipline Exobiology
Non-NASA Center