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Methane from UV-irradiated carbonaceous chondrites under simulated Martian conditions

Schuerger, Andrew C. and Moores, John E. and Clausen, Christian A. and Barlow, Nadine G. and Britt, Daniel T. (2012) Methane from UV-irradiated carbonaceous chondrites under simulated Martian conditions. Journal of Geophysical Research: Planets, 117 (E8). ISSN 2156-2202


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Publisher’s or external URL: http://dx.doi.org/10.1029/2011je004023


A UV photolytic process was studied for the production of methane from carbonaceous chondrites under simulated Martian conditions. Methane evolution rates from carbonaceous chondrites were found to be positively correlated to temperature (−80 to 20°C) and the concentration of carbon in the chondrites (0.2 to 1.69 wt%); and decreased over time with Murchison samples exposed to Martian conditions. The amount of evolved methane (EM) per unit of UV energy was 7.9 × 10−13 mol J−1 for UV irradiation of Murchison (1.69 wt%) samples tested under Martian conditions (6.9 mbar and 20°C). Using a previously described Mars UV model (Moores et al., 2007), and the EM given above, an annual interplanetary dust particle (IDP) accreted mass of 2.4 × 105 kg carbon per year yields methane abundances between 2.2 to 11 ppbv for model scenarios in which 20 to 100% of the accreted carbon is converted to methane, respectively. The UV/CH4 model for accreted IDPs can explain a portion of the globally averaged methane abundance on Mars, but cannot easily explain seasonal, temporal, diurnal, or plume fluctuations of methane. Several impact processes were modeled to determine if periodic emplacement of organics from carbonaceous bolides could be invoked to explain the occurrence of methane plumes produced by the UV/CH4process. Modeling of surface impacts of high-density bolides, single airbursts of low-density bolides, and multiple airbursts of a cascading breakup of a low-density rubble-pile comet were all unable to reproduce a methane plume of 45 ppbv, as reported by Mumma et al.

Item Type: Article
Publisher’s Statement: © 2012 by the American Geophysical Union. To view the published open abstract, go to http://dx.doi.org/10.1029/2011je004023
ID number or DOI: 10.1029/2011JE004023
Keywords: Mars; methane; Martian atmosphere;
Subjects: Q Science > QB Astronomy
NAU Depositing Author Academic Status: Faculty/Staff
Department/Unit: College of Engineering, Forestry, and Natural Science > Physics and Astronomy
Date Deposited: 13 Oct 2015 17:03
URI: http://openknowledge.nau.edu/id/eprint/924

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