2005 Annual Science Report
NASA Ames Research Center Reporting | JUL 2004 – JUN 2005
Biosignatures in Chemosynthetic and Photosynthetic Systems
The microbial population structure and biogeochemical function of microbial mat communities was studied through a combination of fieldwork in Baja California and detailed studies of live samples returned and maintained in a greenhouse facility. Detailed budgets of carbon flow through major chemical pools were constructed via a series of stable isotope-tracing experiments. Incorporation of stable isotope into lipid biomarkers and nucleic acids during these experiments is currently being quantified. Molecular biological techniques were deployed in situ to document systematic shifts in microbial population structure with changes in salinity. These studies are relevant to interpretation of biomarkers and likely community composition in ancient sedimentary deposits hosted in evaporite sequences. They are similarly relevant to potential interpretation of evaporitic systems on Mars.
Co-I David Blake’s CheMin Instrument was selected to fly on the MSL 2009. This provides a very close link between our team’s work and the Mars program. In parallel with its development for flight, CheMin will be deployed to study mineralogy in our field studies (ophiolite and Spitzbergen sites), so that our work can provide directly applicable context for interpretation of MSL science.
A survey of aqueous geochemistry in Northern California ophiolite-hosted springs was continued. We completed a mineralogical, geochemical, and microbial community analysis of Complexion Spring, which suggests extensive serpentization (with potential to support biology via hydrogen release). We began biomarker analysis on chimney samples from the seafloor serpentinizing ultramafic “Lost City” complex, and published work to establish the “energetic habitability” concept as a constraint on subsurface life.
Conducted studies on formation mechanisms of Fe-rich carbonate deposits in basaltic rocks from Spitzbergen and several other locales. This work directly supports an ability to interpret mineralogical and morphological features in Mars meteorites, as related to olivine weathering. A consortium study was initiated on the newly found Martian meteorite NWA2737, which contains abundant brown olivine that has been ascribed to high ferric iron content. Interpretation of this meteorite will contribute to our understanding of ultramafic alteration on Mars.
PROJECT INVESTIGATORS:Tori Hoehler
PROJECT MEMBERS:Daniel Albert
David Des Marais
RELATED OBJECTIVES:Objective 2.1
Earth's early biosphere
Environment-dependent, molecular evolution in microorganisms
Co-evolution of microbial communities
Environmental changes and the cycling of elements by the biota, communities, and ecosystems
Biosignatures to be sought in Solar System materials
Biosignatures to be sought in nearby planetary systems