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Isotopic composition of the Martian atmosphereResults from the neutral mass spectrometer carried on the aeroshell of Viking 1 show evidence for NO in the upper atmosphere of Mars and indicate that the isotopic composition of carbon and oxygen is similar to that of earth. Mars is enriched in N-15 relative to earth by about 75 per cent, a consequence of escape that implies an initial abundance of nitrogen equivalent to a partial pressure of at least 2 millibars. The initial abundance of oxygen present either as CO2 or H2O must be equivalent to an exchangeable atmospheric pressure of at least 2 bars in order to inhibit escape-related enrichment of O-18.
Document ID
19760062471
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
Authors
Nier, A. O.
(Minnesota, University Minneapolis, Minn., United States)
Mcelroy, M. B.
(Harvard Univ. Cambridge, MA, United States)
Yung, Y. L.
(Harvard University Cambridge, Mass., United States)
Date Acquired
August 8, 2013
Publication Date
October 1, 1976
Publication Information
Publication: Science
Volume: 194
Subject Category
Lunar And Planetary Exploration
Accession Number
76A45437
Funding Number(s)
CONTRACT_GRANT: NAS1-9697
CONTRACT_GRANT: NAS1-10492
Distribution Limits
Public
Copyright
Other

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