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Investigating CO2 Reservoirs at Gale Crater and Evidence for a Dense Early AtmosphereOne of the most compelling features of the Gale landing site is its age. Based on crater counts, the formation of Gale crater is dated to be near the beginning of the Hesperian near the pivotal Hesperian/Noachian transition. This is a time period on Mars that is linked to increased fluvial activity through valley network formation and also marks a transition from higher erosion rates/clay mineral formation to lower erosion rates with mineralogies dominated by sulfate minerals. Results from the Curiosity mission have shown extensive evidence for fluvial activity within the crater suggesting that sediments on the floor of the crater and even sediments making up Mt. Sharp itself were the result of longstanding activity of liquid water. Warm/wet conditions on early Mars are likely due to a thicker atmosphere and increased abundance of greenhouse gases including the main component of the atmosphere, CO2. Carbon dioxide is minor component of the Earth's atmosphere yet plays a major role in surface water chemistry, weathering, and formation of secondary minerals. An ancient martian atmosphere was likely dominated by CO2 and any waters in equilibrium with this atmosphere would have different chemical characteristics. Studies have noted that high partial pressures of CO2 would result in increased carbonic acid formation and lowering of the pH so that carbonate minerals are not stable. However, if there were a dense CO2 atmosphere present at the Hesperian/Noachian transition, it would have to be stored in a carbon reservoir on the surface or lost to space. The Mt. Sharp sediments are potentially one of the best places on Mars to investigate these CO2 reservoirs as they are proposed to have formed in the early Hesperian, from an alkaline lake, and record the transition to an aeolian dominated regime near the top of the sequence. The total amount of CO2 in the Gale crater soils and sediments is significant but lower than expected if a thick atmosphere was present at the Hesperian/Noachian boundary. Likewise, the absence of carbonates suggests that CO2- weathering processes similar to those present on Earth were not dominant. Instead it is possible that more exotic CO2 deposition has occurred driven by atmospheric photochemistry and/or degradation of organic carbon.
Document ID
20150002922
Acquisition Source
Johnson Space Center
Document Type
Conference Paper
Authors
Niles, P. B. (NASA Johnson Space Center Houston, TX, United States)
Archer, P. D. (Jacobs Technology, Inc. Houston, TX, United States)
Heil, E. (Jacobs Technologies Engineering Science Contract Group Houston, TX, United States)
Eigenbrode, J. (NASA Goddard Space Flight Center Greenbelt, MD, United States)
McAdam, A. (NASA Goddard Space Flight Center Greenbelt, MD, United States)
Sutter, B. (Jacobs Technology, Inc. Houston, TX, United States)
Franz, H. (NASA Goddard Space Flight Center Greenbelt, MD, United States)
Navarro-Gonzalez, R. (Instituto Andaluz de Ciencias de la Tierra Granada, Spain)
Ming, D. (NASA Johnson Space Center Houston, TX, United States)
Mahaffy, P. R. (NASA Goddard Space Flight Center Greenbelt, MD, United States)
Martin-Torres, F. J. (Instituto Andaluz de Ciencias de la Tierra Granada, Spain)
Zorzano, M. (Instituto Nacional de Tecnica Aeroespacial Madrid, Spain)
Date Acquired
March 13, 2015
Publication Date
March 16, 2015
Subject Category
Lunar And Planetary Science And Exploration
Report/Patent Number
JSC-CN-32884
Meeting Information
Meeting: Lunar and Planetary Science Conference
Location: The Woodlands, TX
Country: United States
Start Date: March 16, 2015
End Date: March 20, 2015
Sponsors: Lunar and Planetary Inst.
Distribution Limits
Public
Copyright
Public Use Permitted.

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