title: Mars atmosphere. Mars methane detection and variability at Gale crater.
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.
authors.affiliation: Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109, USA. chris.r.webster@jpl.nasa.gov.
authors.forename: Christopher R
authors.initials: CR
authors.lastname: Webster
authors.affiliation: NASA Goddard Space Flight Center, Greenbelt, MD 20771, USA.
authors.forename: Paul R
authors.initials: PR
authors.lastname: Mahaffy
authors.affiliation: University of Michigan, Ann Arbor, MI 48109, USA.
authors.forename: Sushil K
authors.initials: SK
authors.lastname: Atreya
authors.affiliation: Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109, USA.
authors.forename: Gregory J
authors.initials: GJ
authors.lastname: Flesch
authors.affiliation: Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109, USA.
authors.forename: Michael A
authors.initials: MA
authors.lastname: Mischna
authors.affiliation: Institut de Recherche en Astrophysique et Planétologie, UPS-OMP, CNRS, 31028 Toulouse, France.
authors.forename: Pierre-Yves
authors.initials: PY
authors.lastname: Meslin
authors.affiliation: California Institute of Technology, Pasadena, CA 91125, USA.
authors.forename: Kenneth A
authors.initials: KA
authors.lastname: Farley
authors.affiliation: NASA Goddard Space Flight Center, Greenbelt, MD 20771, USA.
authors.forename: Pamela G
authors.initials: PG
authors.lastname: Conrad
authors.affiliation: Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109, USA.
authors.forename: Lance E
authors.initials: LE
authors.lastname: Christensen
authors.affiliation: NASA Goddard Space Flight Center, Greenbelt, MD 20771, USA.
authors.forename: Alexander A
authors.initials: AA
authors.lastname: Pavlov
authors.affiliation: Instituto Andaluz de Ciencias de la Tierra [Consejo Superior de Investigaciones Científicas (CSIC)-Universidad de Granada], Granada, Spain. Division of Space Technology, Luleå University of Technology, Kiruna, Sweden.
authors.forename: Javier
authors.initials: J
authors.lastname: Martín-Torres
authors.affiliation: Centro de Astrobiologia, Instituto Nacional de Técnica Aeroespacial-CSIC, Madrid, Spain.
authors.forename: María-Paz
authors.initials: MP
authors.lastname: Zorzano
authors.affiliation: Department of Astronomy, University of Maryland, College Park, MD 20742, USA.
authors.forename: Timothy H
authors.initials: TH
authors.lastname: McConnochie
authors.affiliation: University of Hawaii, Honolulu, HI 96822, USA.
authors.forename: Tobias
authors.initials: T
authors.lastname: Owen
authors.affiliation: NASA Goddard Space Flight Center, Greenbelt, MD 20771, USA.
authors.forename: Jennifer L
authors.initials: JL
authors.lastname: Eigenbrode
authors.affiliation: NASA Goddard Space Flight Center, Greenbelt, MD 20771, USA.
authors.forename: Daniel P
authors.initials: DP
authors.lastname: Glavin
authors.affiliation: Carnegie Institution of Washington, Washington, DC 20015, USA.
authors.forename: Andrew
authors.initials: A
authors.lastname: Steele
authors.affiliation: NASA Goddard Space Flight Center, Greenbelt, MD 20771, USA.
authors.forename: Charles A
authors.initials: CA
authors.lastname: Malespin
authors.affiliation: Jacobs Technology, NASA Johnson Space Center, Houston, TX 77058, USA.
authors.forename: P Douglas
authors.initials: PD
authors.lastname: Archer
authors.affiliation: Jacobs Technology, NASA Johnson Space Center, Houston, TX 77058, USA.
authors.forename: Brad
authors.initials: B
authors.lastname: Sutter
authors.affiliation: Laboratoire Inter-Universitaires Des Systèmes Atmosphériques (LISA), UMR CNRS 7583, Paris, France.
authors.forename: Patrice
authors.initials: P
authors.lastname: Coll
authors.affiliation: NASA Goddard Space Flight Center, Greenbelt, MD 20771, USA.
authors.forename: Caroline
authors.initials: C
authors.lastname: Freissinet
authors.affiliation: NASA Ames Research Center, Mountain View, CA 94035, USA.
authors.forename: Christopher P
authors.initials: CP
authors.lastname: McKay
authors.affiliation: York University, Toronto, Ontario M3J 1P3, Canada.
authors.forename: John E
authors.initials: JE
authors.lastname: Moores
authors.affiliation: The Open University, Milton Keynes MK7 6AA, UK.
authors.forename: Susanne P
authors.initials: SP
authors.lastname: Schwenzer
authors.affiliation: Space Research Centre, University of Leicester, Leicester LE1 7RH, UK.
authors.forename: John C
authors.initials: JC
authors.lastname: Bridges
authors.affiliation: Instituto de Ciencias Nucleares, Universidad Nacional Autonoma de Mexico, Mexico City 04510, Mexico.
authors.forename: Rafael
authors.initials: R
authors.lastname: Navarro-Gonzalez
authors.affiliation: University of Guelph, Guelph, Ontario N1G 2W1, Canada.
authors.forename: Ralf
authors.initials: R
authors.lastname: Gellert
authors.affiliation: Texas A&M University, College Station, TX 77843, USA.
authors.forename: Mark T
authors.initials: MT
authors.lastname: Lemmon