NASA Astrobiology Institute (NAI)

1. Stability of methane hydrates in the presence of high salinity brines on Mars

   Project Investigators: Tommy Phelps

   Other Project Members

   Megan Elwood Madden (Post-Doctoral Researcher)

   Susan Pfiffner (Collaborator)

   Summary

   Laboratory experiments were used to monitor the influence of increasing salinity on the stability of ices composed of water, methane, and carbon dioxide. New data show that these types of hydrates decease in stability as salinity increases, suggesting that lateral or vertical migration of brines in the subsurface of Mars could cause release of methane and carbon dioxide to surface sediments and the atmosphere. These experimental results are important for interpreting reports of methane in the Martian atmosphere.

   Astrobiology Roadmap Objectives:

   • Objective 2.1: Mars exploration
   • Objective 2.2: Outer Solar System exploration
   • Objective 3.1: Sources of prebiotic materials and catalysts
   • Objective 7.1: Biosignatures to be sought in Solar System materials
   • Objective 7.2: Biosignatures to be sought in nearby planetary systems

   Project Progress

   Stability of methane hydrates in the presence of high salinity brines on Mars

   Progress report

   Recent observations of methane in the highly oxidizing atmosphere of Mars suggest that methane has been added relatively recently. Several mechanisms for recent methane release have been proposed in the scientific literature including subsurface biological methanogenesis, abiogenic hydrothermal and/or volcanic activity, weathering of ultramafic deposits to serpentenites, dissociation of methane hydrates, atmospheric photolysis, or addition of organics via bolide impact. This laboratory study examines the effects of increasing salinity on gas hydrate stability and compares estimates of the Martian geothermal gradient to methane and carbon dioxide hydrate stability fields in the presence of high salinity brines. The results demonstrate that salinity increases alone result in a significant decrease in the predicted hydrate stability zone under conditions inferred to exit in the Martian subsurface. Thus, lateral or vertical movement of brines in the Martian subsurface may be a driving force in methane hydrate destabilization. Active thermal and/or pressure fluctuations are not required in order for methane hydrates to be the source of atmospheric methane.

Publications

Arino de la Rubia, L.  (2007a).  Development, Evaluation, and Dissemination of an Astrobiology Curriculum for Secondary Students: Establishing a successful model for increasing the use of scientific data by underrepresented students.  Bioastronomy 2007.

Arino de la Rubia, L.  (2007b).  Development, Evaluation, and Dissemination of an Astrobiology Curriculum for Secondary Students: Establishing a successful model for increasing the use of scientific data by underrepresented students..  Bioastronomy 2007.  San Juan, Puerto Rico.

Bakermans, C.  (2008).  Microbial Communities in Subpermafrost Brine.  Alpine and Polar Microbiology Conference.  Baniff, Alberta, Canada.

Bakermans, C.  (2008).  Microbial sulfur cycling in subpermafrost saline fracture water at the Lupin gold mine, Nunavut, Canada.  Environmental Microbiology (submitted).

Butler, J.  (2008).  Focus on diversity: field testing the astrobiology in secondary classrooms curriculum.  Astrobiology Science Conference.  Santa Clara, CA.

Davidson M.. Pratt, L.M.  (2008).  Enhancing fractionation of stable sulfur isotopes during maintenance metabolism of a thermophilic sulfate-reducing bacterium cultivated in a retentostat.  Astrobiology Science Conference.  Santa Clara, CA.

Freifeld, B.M.  (2008).  Deployment of a Deep Borehole Observatory at High Lake Project Site, Nunavut, Canada.  9th International Permafrost Conference.  Fairbanks, Alaska.

Li, Y. & Phelps, T.J.  (2008).  Degeneration of Biogenic Superparamagnetic Magnetite.  Geobiology Journal (in revision).

Mix, L.J.  (2006).  The astrobiology primer: An outline of general knowledge - version 1, 2006.  Astrobiology, 6:735-813.

Pfiffner, S.M. & Pratt, L.M.  (2008).  Challenges for Coring Deep Permafrost on Earth and Mars.  Alpine and Polar Microbiology Conference.  Baniff, Alberta, Canada.

Pfiffner, S.M.  (2006).  The Search for Life in the Deep Subsurface: Membrane Lipid Biosignatures.  Geological Society of America.  Philadelphia, PA.

Pfiffner, S.M.  (2008).  Examining microbial community profiles form natural acid rock drainage at Peekaboo Gulch Colorado.  American Society for Microbiology.  Boston, MA.

Pfiffner, S.M.  (2008).  What do membrane lipids tell us about the microorganisms living in extreme environments?.  SPIE Instruments, Methods, and Missions for Astrobiology XI.  San Diego, CA.

Webster, C.E.  (2007).  Biogeochemical Analysis of Microbial Community Structure in Alpine Peekaboo Gulch, Colorado.  GSA.  Denver, CO.

Webster, C.E.  (2008).  Microbial community structure in central and eastern Grizzly Peak Caldera, Colorado.  Alpine and Polar Microbiology Conference.  Baniff, Alberta, Canada.