| Literature DB >> 25515120 |
Christopher R Webster1, Paul R Mahaffy2, Sushil K Atreya3, Gregory J Flesch4, Michael A Mischna4, Pierre-Yves Meslin5, Kenneth A Farley6, Pamela G Conrad2, Lance E Christensen4, Alexander A Pavlov2, Javier Martín-Torres7, María-Paz Zorzano8, Timothy H McConnochie9, Tobias Owen10, Jennifer L Eigenbrode2, Daniel P Glavin2, Andrew Steele11, Charles A Malespin2, P Douglas Archer12, Brad Sutter12, Patrice Coll13, Caroline Freissinet2, Christopher P McKay14, John E Moores15, Susanne P Schwenzer16, John C Bridges17, Rafael Navarro-Gonzalez18, Ralf Gellert19, Mark T Lemmon20.
Abstract
Reports of plumes or patches of methane in the martian atmosphere that vary over monthly time scales have defied explanation to date. From in situ measurements made over a 20-month period by the tunable laser spectrometer of the Sample Analysis at Mars instrument suite on Curiosity at Gale crater, we report detection of background levels of atmospheric methane of mean value 0.69 ± 0.25 parts per billion by volume (ppbv) at the 95% confidence interval (CI). This abundance is lower than model estimates of ultraviolet degradation of accreted interplanetary dust particles or carbonaceous chondrite material. Additionally, in four sequential measurements spanning a 60-sol period (where 1 sol is a martian day), we observed elevated levels of methane of 7.2 ± 2.1 ppbv (95% CI), implying that Mars is episodically producing methane from an additional unknown source.Entities:
Year: 2014 PMID： 25515120 DOI： 10.1126/science.1261713
Source DB: PubMed Journal: Science ISSN： 0036-8075 Impact factor: 47.728