HR: 10:55h
AN: B51G-03 INVITED     [PDF]
TI: Exploring for Biosignatures of Extant Life in Martian Ground Ice
AU: * Farmer, J
EM: jfarmer@asu.edu
AF: Jack D. Farmer, Arizona State University, Dept. of Geological Sciences, P.O. Box 871404, Tempe, AZ 85287-1404 United States
AB: The strategy for the next decade of Mars exploration emphasizes the discovery of favorable sites for sampling ancient, aqueously-formed sedimentary rocks, especially those capable of capturing and preserving fossil biosignatures. Nevertheless, it is widely accepted that habitable zones of deep groundwater, able to support extant Martian life, could also be present in the subsurface today. Generally speaking, access to subsurface groundwater habitats could require drilling to depths of several km, far deeper than could be accomplished with the current generation of robotic landers and rovers. But, in the absence of advanced drilling technologies and perhaps human explorers needed to operate them, is it still possible, with present capabilities, to gain access to a deep subsurface hydrosphere on Mars during the robotic phase of exploration? Subsurface cryosphere-magma interactions appear to have been active throughout Martian history. Magma bodies emplaced into the shallow cryosphere would set up deeply convecting hydrothermal systems that would, in turn, carry subsurface organic chemistry and any organisms present in subsurface groundwater, upward into the shallow crust. Upon cooling, these materials could be incorporated into shallow ground ice. Such ice deposits may be accessible to future surface robotic missions via shallow drilling (tens to hundreds of meters depth) of recently active igneous/volcanic areas. Discoveries from the Mars Global Surveyor and Odyssey missions have already discovered several geological environments on Mars favorable for such magma-cryosphere processes. These include numerous small gully systems ("seeps"), mostly found on steep, poleward-facing slopes at high latitudes (Malin and Edgett 2000; Christensen 2003), sites marginal to the Martian polar caps where periodic outflooding events appear to have occurred (Clifford 1987) and recent volcanic constructs situated in ground ice-rich regions at high latitudes. While the strategy for exploring for cryopreserved biosignatures of extant life in near surface ice deposits needs additional study, it appears that the shallow cryosphere of Mars offers many tantalizing opportunities for future astrobiological exploration.
DE: 0400 Biogeosciences
DE: 1863 Snow and ice (1827)
DE: 4840 Microbiology
DE: 6225 Mars
DE: 8424 Hydrothermal systems (8135)
SC: Biogeosciences [B]
MN: 2003 Fall Meeting