HR: 17:15h
AN: P42C-06    [PDF]
TI: Subsurface Halophilic Microbial Communities in the Hyperarid Core of the Atacama Desert: An Analog for Possible Subsurface Life in Regolith on Mars
AU: Oren, A
EM: orena@c.huji.ac.il
AF: Division of Microbial and Molecular Ecology, The Institute of Life Sciences The Hebrew University of Jerusalem, Jerusalem, 91904 Israel
AU: * Warren-Rhodes, K
EM: kwarren-rhodes@mail.arc.nasa.gov
AF: NASA-Ames Research Center, Planetary Sciences Mail Stop 245-3, Moffett Field, CA 94035 United States
AU: Rainey, F T
EM: frainey@lsu.edu
AF: Louisiana State University, Department of Biological Sciences 508 Life Sciences Building, Baton Rouge, LA 70803 United States
AU: Ewing, S
EM: saewing@nature.berkeley.edu
AF: University of California at Berkeley, Ecosystem Sciences Division Department of Environmental Science, Policy and Management, Berkeley, CA 94720 United States
AU: McKay, C P
EM: cmckay@mail.arc.nasa.gov
AF: NASA-Ames Research Center, Planetary Sciences Mail Stop 245-3, Moffett Field, CA 94035 United States
AB: The Atacama Desert in its driest portion provides an interesting analog for possible past or present life in the Martian regolith. In the hyperarid core of the Atacama, surface soils are virtually abiotic, with no plants and "near sterile" concentrations of heterotrophic bacteria (i.e., exceedingly low densities of approximately 100 colony forming units per gram soil). The dearth of microbial life at the surface is likely maintained through extremely low water availability, low organic content and the highly oxidizing nature of the soil. In marked contrast to the surface, however, extremely halophilic microorganisms exist in salt layers 1.2-1.5m below the surface. Mineralogical analyses indicate the layers are predominantly halite (70% NaCl) but also contain sodium nitrate (5% NaNO3). Culturing and polar lipid analyses suggest the halophiles are archaeal Halobacterium-like motile rods. Microclimate monitoring at 1m indicates a soil relative humidity of 20% which is stable year-round even during decadal rain events such as that experienced in July 2002. This suggests the layers are isolated from even significant moisture influxes at the surface. Although further research is necessary, important parallels exist between this Earthly desert analog and the possible existence and detection of subsurface life on Mars despite harsh abiotic conditions at the surface.
DE: 6225 Mars
SC: Planetary Sciences [P]
MN: 2003 Fall Meeting