37th DPS Meeting, 4-9 September 2005
Session 53 Titan III
Oral, Thursday, September 8, 2005, 4:20-6:00pm, Music Concert Hall

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[53.09] Possible Niches for Extant Life on Titan in Light of Cassini/Huygens Results

D.H. Grinspoon, M.A. Bullock, J.R. Spencer (SwRI), D. Schulze-Makuch (WSU)

Results from the first year of the Cassini mission show that Titan has an active surface with few impact craters and abundant hints of cryovolcanism, tectonism, aeolian and fluvial activity (Porco et al., 2005; Elachi et al., 2005). Methane clouds and surface characteristics strongly imply the presence of an active global methane cycle analogous to Earth's hydrological cycle. Astrobiological interest in Titan has previously focused on possible prebiological chemical evolution on a moon with a thick nitrogen atmosphere and rich organic chemistry (Raulin and Owen, 2002). Yet the emerging new picture of Titan has raised prospects for the possibility of extant life. Several key requirements for life appear to be present, including liquid reservoirs, organic molecules and ample energy sources. One promising location may be hot springs in contact with hydrocarbon reservoirs. Hydrogenation of photochemically produced acetylene could provide metabolic energy for near-surface organisms and also replenish atmospheric methane (Schulze-Makuch and Grinspoon, 2005). The energy released could be used by organisms to drive endothermic reactions, or go into heating their surroundings, helping to create their own liquid microenvironments. In environments which are energy-rich but liquid-poor, like the near-surface of Titan, natural selection may favor organisms that use their ``waste heat" to melt their own watering holes. Downward transport of high energy photochemical compounds could provide an energy supply for near-surface organisms which could be used, in part, to maintain the liquid environments conducive to life. We will present the results of thermal modeling designed to test the feasibility of biothermal melting on Titan.

C. Porco and the Cassini Imaging Team (2005) Nature 434, 159-168; C. Elachi et al, Science, 308, 970-974; F. Raulin and T. Owen (2002) Space Sci. Rev. 104, 377 - 394.; D. Schulze-Makuch and D. H. Grinspoon (2005) Astrobiology, in press.

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