HR: 0800h
AN: P11C-0703    [Abstracts]
TI: Assessing the Habitability and the Biogeochemical Output of Subsurface Biomes
AU: * Schrenk, M
EM: mschrenk@gl.ciw.edu
AF: Carnegie Institution of Washington- Geophysical Laboratory, 5251 Broad Branch Rd. NW, Washington, DC 20015, United States
AU: Seager, S
EM: seager@mit.edu
AF: Massachusetts Institute of Technology, Department of Earth, Atmospheric, and Planetary Sciences 77 Massachusetts Ave., Cambridge, MA 02139, United States
AB: The subsurface microbial biosphere has been estimated to represent the largest biome on Earth in terms of sheer volume of habitable space. Even if the magnitude of the subsurface biosphere is vastly overestimated, it could still represent a significant reservoir of nutrients, and harbor yet-to-be-discovered metabolic and physiological diversity. Subsurface environments have also been evoked as some of the most likely sites for extraterrestrial life as they are sheltered from harsh surface conditions, may retain liquid water, and may be linked to geothermal and geochemical energy sources. Despite the recognized importance of these environments, relatively little is known about factors constraining the habitability of subsurface ecosystems, or how these factors influence life detection through either in situ or remote measurements. We present a two part model in which we evaluate the habitability of subsurface environments based upon the physiological characteristics of specific metabolic groups of microorganisms (e.g. methanogens, sulfate reducers, etc.) then assess the potential for detection of their biosignatures through both direct and remote measurements. Easily parameterized values such as temperature, pressure, and pore space will be compared with free energy fluxes derived from models of subsurface environments. These data will be used to determine the rates, character, and magnitude of biosignatures produced. Since local influences such as the spatial and temporal scales of habitable niches may have important consequences for life, these factors will be evaluated. The geometry and composition of host materials will also be incorporated into the models, as this may either dampen, or record evidence of biological activities. This research provides a key framework for testing hypotheses based upon on observational data on Earth, and may lead to new insights into prospecting for life in subsurface environments on Mars, Europa, and rocky extrasolar planets.
DE: 0448 Geomicrobiology
DE: 1055 Organic and biogenic geochemistry
DE: 1615 Biogeochemical cycles, processes, and modeling (0412, 0414, 0793, 4805, 4912)
DE: 4815 Ecosystems, structure, dynamics, and modeling (0439)
DE: 6296 Extra-solar planets
SC: Planetary Sciences [P]
MN: 2007 Fall Meeting