Background levels of methane in Mars’ atmosphere show strong seasonal variations

Christopher R. Webster(Jet Propulsion Laboratory), P. R. Mahaffy(Goddard Space Flight Center), S. K. Atreya(University of Michigan), John E. Moores(York University), Gregory J. Flesch(Jet Propulsion Laboratory), C. A. Malespin(Goddard Space Flight Center), Christopher P. McKay(Ames Research Center), Germán Martínez(University of Michigan), C. L. Smith(York University), Javier Martín‐Torres(Luleå University of Technology), Javier Gomez-Elvira(Instituto Nacional de Técnica Aeroespacial), María‐Paz Zorzano(Luleå University of Technology), Michael H. Wong(University of Michigan), M. G. Trainer(Goddard Space Flight Center), A. Steele(Carnegie Institution for Science), Doug Archer(Johnson Space Center), B. Sutter(Johnson Space Center), Patrice Coll(Laboratoire Interuniversitaire des Systèmes Atmosphériques), Caroline Freissinet(Laboratoire atmosphères, milieux, observations spatiales), Pierre‐Yves Meslin(Institut de Recherche en Astrophysique et Planétologie), R. V. Gough(Cooperative Institute for Research in Environmental Sciences), Christopher H. House(Pennsylvania State University), Alexander A. Pavlov(Goddard Space Flight Center), J. L. Eigenbrode(Goddard Space Flight Center), D. P. Glavin(Goddard Space Flight Center), John C. Pearson(Jet Propulsion Laboratory), Didier Keymeulen(Jet Propulsion Laboratory), L. E. Christensen(Jet Propulsion Laboratory), S. P. Schwenzer(The Open University), R. Navarro‐González(Universidad Nacional Autónoma de México), Jorge Pla‐García(Space Science Institute), Scot Rafkin(Southwest Research Institute), Á. Vicente‐Retortillo(University of Michigan), Henrik Kahanpää(Finnish Meteorological Institute), Daniel Viúdez‐Moreiras(Instituto Nacional de Técnica Aeroespacial), M. D. Smith(Goddard Space Flight Center), Ari‐Matti Harri(Finnish Meteorological Institute), María Genzer(Finnish Meteorological Institute), Donald M. Hassler(Southwest Research Institute), M. T. Lemmon(Texas A&M University), J. A. Crisp(Jet Propulsion Laboratory), Stanley P. Sander(Jet Propulsion Laboratory), Richard W. Zurek(Jet Propulsion Laboratory), A. R. Vasavada(Jet Propulsion Laboratory)
Science
June 7, 2018
10.1126/science.aaq0131
Cited by 319Open Access
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Abstract

Variable levels of methane in the martian atmosphere have eluded explanation partly because the measurements are not repeatable in time or location. We report in situ measurements at Gale crater made over a 5-year period by the Tunable Laser Spectrometer on the Curiosity rover. The background levels of methane have a mean value 0.41 ± 0.16 parts per billion by volume (ppbv) (95% confidence interval) and exhibit a strong, repeatable seasonal variation (0.24 to 0.65 ppbv). This variation is greater than that predicted from either ultraviolet degradation of impact-delivered organics on the surface or from the annual surface pressure cycle. The large seasonal variation in the background and occurrences of higher temporary spikes (~7 ppbv) are consistent with small localized sources of methane released from martian surface or subsurface reservoirs.

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