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Chemical and physical microenvironments at the Viking landing sitesPhysical and chemical considerations permit the division of the near-surface regolith on Mars into at least six zones of distinct microenvironments. The zones are euphotic, duricrust/peds, tempofrost, permafrost, endolithic, and interfacial/transitional. Microenvironments vary significantly in temperature extremes, mean temperature, salt content, relative pressure of water vapor, UV and visible light irradiance, and exposure to ionizing radiation events (100 Mrad) and oxidative molecular species. From what is known of the chemistry of the atmosphere and regolith fines (soil), limits upon the aqueous chemistry of soil pastes may be estimated. Heat of wetting could reach 45 cal/g dry soil; initial pH is indeterminate between 1 and 10; ionic strength and salinity are predicted to be extremely high; freezing point depression is inadequate to provide quantities of liquid water except in special cases. The prospects for biotic survival are grim by terrestrial standards, but the extremes of biological resiliency are inaccessible to evaluation. Second-generation in situ experiments which will better define Martian microenvironments are clearly possible. Antarctic dry valleys are approximations to Martian conditions, but deviate significantly by at least half-a-dozen criteria.
Document ID
19800051885
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
External Source(s)
Authors
Clark, B. C.
(Martin Marietta Aerospace Planetary Sciences Laboratory Denver, Colo., United States)
Date Acquired
August 10, 2013
Publication Date
December 1, 1979
Publication Information
Publication: Journal of Molecular Evolution
Volume: 14
Subject Category
Lunar And Planetary Exploration
Accession Number
80A36055
Funding Number(s)
CONTRACT_GRANT: NAS1-9000
Distribution Limits
Public
Copyright
Other

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