Mars Methane at Gale Crater Shows Strong Seasonal Cycle: Updated Results from TLS-SAM on Curiosity

C. R. Webster, P. R. Mahaffy, S. K. Atreya, G. Flesch, C. Malespin, C. McKay, G. Martinez, J. Moores, C. L. Smith, F. J. Martin-Torres, J. Gomez-Elvira, M. P. Zorzano, M. H. Wong, M. G. Trainer, J. L. Eigenbrode, D. P. Glavin, A. Steele, Jr. Archer D., B. Sutter, P. J. CollC. Freissinet, P. Y. Meslin, A. Pavlov, D. Keymeulen, L. E. Christensen, R. V. Gough, S. P. Schwenzer, R. Navarro-Gonzalez, J. Pla-García, S. C. Rafkin, Á. Vicente-Retortillo, H. Kahanpää, D. Viudez-Moreiras, M. D. Smith, A. M. Harri, M. Genzer, D. Hassler, M. T. Lemmon, J. A. Crisp, R. W. Zurek, A. R. Vasavada

Research output: Contribution to conferenceAbstract

Abstract

In situ measurements of atmospheric methane have been made over a 5-year period at Gale Crater on Mars using the Tunable Laser Spectrometer (TLS) instrument in the Sample Analysis at Mars (SAM) suite on the Curiosity rover. We report two important observations: (i) a background level of mean value of 0.41 ±0.11 (2sem) that is about 5 times lower than some model predictions based on generation from UV degradation of micro- meteorites or interplanetary dust delivered to the martian surface; (ii) "spikes" of elevated levels of 7 ppbv attributed to episodic releases from small local sources, probably to the north of Gale crater1. Reports of plumes, patches or episodic releases of methane in the Martian atmosphere have to date eluded explanation in part because of their lack of repeatability in time or location. Our in situ measurements of the background methane levels exhibit a strong, repeatable seasonal variability. The amplitude of the observed seasonal cycle is 3 times greater than both that expected from the annual sublimation and freezing of polar carbon dioxide and that expected from methane production from ultraviolet (UV) degradation of exogenously-delivered surface material. The observed large seasonal variation in the background, and sporadic observations of higher pulses of 7 ppbv appear consistent with localized small sources of methane release from Martian surface reservoirs that may be occurring throughout the planet. We will present our updated data set, correlations of Mars methane with various other measurements from SAM, REMS, RAD and ChemCam instruments on Curiosity, as well as empirical models of UV surface insolation, and provide preliminary interpretation of results. 1 "Mars Methane Detection and Variability at Gale Crater", C. R. Webster et al., Science, 347, 415-417 (2015) and references therein. The research described here was carried out in part at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration (NASA).
Original languageEnglish
Publication statusPublished - Dec 2017
EventAGU Fall Meeting 2017 - New Orleans, United States
Duration: 11 Dec 201715 Dec 2017

Conference

ConferenceAGU Fall Meeting 2017
CountryUnited States
CityNew Orleans
Period11/12/1715/12/17

Keywords

  • 5215 Origin of life
  • PLANETARY SCIENCES: ASTROBIOLOGY
  • 6225 Mars
  • PLANETARY SCIENCES: SOLAR SYSTEM OBJECTS
  • 5455 Origin and evolution
  • PLANETARY SCIENCES: SOLID SURFACE PLANETS
  • 5470 Surface materials and properties

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