Curiosity and the Four Seasons: In Situ Measurements of the Atmospheric Composition over Three Mars Years

M. G. Trainer, H. B. Franz, P. R. Mahaffy, C. Malespin, M. H. Wong, S. K. Atreya, R. H. Becker, P. G. Conrad, F. Lefèvre, H. L. K. Manning, F. J. Martin-Torres, T. McConnochie, C. McKay, R. Navarro-Gonzalez, R. O. Pepin, C. R. Webster, M. P. Zorzano

Research output: Contribution to conferenceAbstract


The Sample Analysis at Mars (SAM) instrument onboard the Mars science Laboratory Curiosity rover measures the chemical composition of major atmospheric species in the vicinity of the rover through a dedicated atmospheric inlet. We report here on measurements of atmospheric volume mixing ratios in Gale Crater using the SAM quadrupole mass spectrometer (QMS), over a period of nearly three Mars years (5 Earth years) from landing. The observation period spans the southern winter of MY 31, solar longitude (Ls) of 175° through southern fall of MY 34, Ls = 12°. The initial mixing ratios measured by the SAM QMS were reported for the first 105 sols of the mission [1], and were updated to account for newly developed calibration factors [2]. The SAM QMS atmospheric measurements were continued, periodically interspersed between solid sample measurements and other rover activities, with a cumulative coverage of 4 or 5 experiments per season. The three major volatiles - CO2, N2, and 40Ar - are compatible with the annual pressure cycle but with a repeatable lag that indicates incomplete mixing and the influences of seasonal circulation patterns. The mixing ratios for the two inert, non- condensable species are qualitatively consistent with what is predicted from annual cycle of CO2 deposition and sublimation at the poles, which is manifested in a large enhancement of Ar mixing ratio at the winter poles (and assumed for N2) [3]. The mixing ratio for the minor species O2 appears to follow a distinct seasonal trend and may be indicative of possible deviations from known atmospheric chemistry or a surface flux of oxygen from an unknown source, or both. This unprecedented seasonal coverage and precision in mixing ratio determination provides valuable data for understanding the seasonal chemical and dynamics cycles. Further, this measurement campaign supplies useful ground-truth data for global climate model simulations, which can study atmospheric effects for other locations on Mars as well as long-term evolution of Mars climate.
Original languageEnglish
Publication statusPublished - Dec 2017
EventAGU Fall Meeting 2017 - New Orleans, United States
Duration: 11 Dec 201715 Dec 2017


ConferenceAGU Fall Meeting 2017
Country/TerritoryUnited States
CityNew Orleans

Bibliographical note

Abstract #P33I-05


  • 3346 Planetary meteorology
  • 6225 Mars
  • 5405 Atmospheres
  • 5445 Meteorology


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