Low HesperianPCO2constrained from in situ mineralogical analysis at Gale Crater, Mars.
Carbon dioxide is an essential atmospheric component in martian climate models that attempt to reconcile a faint young sun with planetwide evidence of liquid water in the Noachian and Early Hesperian. In this study, we use mineral and contextual sedimentary environmental data measured by the Mars Science Laboratory (MSL) RoverCuriosityto estimate the atmospheric partial pressure of CO2(PCO2) coinciding with a long-lived lake system in Gale Crater at ∼3.5 Ga. A reaction-transport model that simulates mineralogy observed within the Sheepbed member at Yellowknife Bay (YKB), by coupling mineral equilibria with carbonate precipitation kinetics and rates of sedimentation, indicates atmosphericPCO2levels in the 10s mbar range. At such lowPCO2levels, existing climate models are unable to warm Hesperian Mars anywhere near the freezing point of water, and other gases are required to raise atmospheric pressure to prevent lake waters from being lost to the atmosphere. Thus, either lacustrine features of Gale formed in a cold environment by a mechanism yet to be determined, or the climate models still lack an essential component that would serve to elevate surface temperatures, at least locally, on Hesperian Mars. Our results also impose restrictions on the potential role of atmospheric CO2in inferred warmer conditions and valley network formation of the late Noachian.
Exobiology Branch, NASA Ames Research Center, Moffett Field, CA 94035; thomas.f.bristow@nasa.gov.
Thomas F
TF
Bristow
Planetary Systems Branch, NASA Ames Research Center, Moffett Field, CA 94035.
Robert M
RM
Haberle
Exobiology Branch, NASA Ames Research Center, Moffett Field, CA 94035.
David F
DF
Blake
Exobiology Branch, NASA Ames Research Center, Moffett Field, CA 94035.
David J
DJ
Des Marais
Solar System Exploration Division, NASA Goddard Space Flight Center, Greenbelt, MD 20771.
Jennifer L
JL
Eigenbrode
Department of Planetology and Habitability, Centro de Astrobiología, Madrid 28850, Spain.
Alberto G
AG
Fairén
Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, CA 91125.
John P
JP
Grotzinger
Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109.
Kathryn M
KM
Stack
Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109.
Michael A
MA
Mischna
Astromaterials Research and Exploration Science Division, NASA Johnson Space Center, Houston, TX 77058.
Elizabeth B
EB
Rampe
Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, CA 91125.
Kirsten L
KL
Siebach
Jacobs Technology, Inc., NASA Johnson Space Center, Houston, TX 77058.
Brad
B
Sutter
Planetary Science Institute, Tucson, AZ 85719.
David T
DT
Vaniman
Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109.
Ashwin R
AR
Vasavada
Gale Crater; Hesperian Mars; Mars Science Laboratory; carbon dioxide; martian atmosphere