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

Christopher R. Webster, Paul R. Mahaffy, Sushil K. Atreya, John E. Moores, Gregory J. Flesch, Charles A. Malespin, Christopher P. McKay, German Martinez, Christina L. Smith, Javier Martin-Torres, María-Paz Zorzano, Michael H. Wong, Melissa G. Trainer, Andrew Steele, Doug Archer Jr, Brad Sutter, Patrice J Coll, Caroline Freissinet, Pierre-Yves Meslin, Raina V GoughChristopher H House, Alexander A. Pavlov, Jennifer L. Eigenbrode, Daniel P. Glavin, John C Pearson, Didier Keymeulen, Lance E. Christensen, Susanne P. Schwenzer, Rafael Navarro‐González, Jorge Pla-Garcia, Scot C. R. Rafkin, Álvaro Vicente Retortillo, Henrik Kahanpää, Daniel Viudez-Moreiras, Michael D. Smith, Ari-Matti Harri, Maria Genzer, Donald M. Hassler, Mark Lemmon, Joy Crisp, Stanley P. Sander, Richard W. Zurek, Ashwin R Vasavada

Research output: Contribution to journalArticle

74 Citations (Scopus)

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.
Original languageEnglish
Pages (from-to)1093-1096
Number of pages4
JournalScience
Volume360
Issue number6393
Early online date8 Jun 2018
DOIs
Publication statusPublished - 8 Jun 2018

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