Asrobiologia de cometas

Astrobiology of Comets

Richard B. Hoovera1, Elena V. Pikutaa, Nalin C. Wickramasingheb, Max K. Wallisb, Robert B. Sheldona

aAstrobiology Laboratory, NASA/MSFC/NSSTC, 320 Sparkman Dr., Huntsville, AL USA 35805;

bCardiff Centre for Astrobiology, Cardiff University, UK.

ABSTRACT

We review the current state of knowledge concerning microbial extremophiles and comets and the potential significance of comets to Astrobiology. We model the thermal history of a cometary body, regarded as an assemblage of boulders, dust, ices and organics, as it approaches a perihelion distance of ~ 1AU. The transfer of incident energy from sunlight into the interior leads to the melting of near surface ices, some under stable porous crust, providing possible habitats for a wide range of microorganisms. We provide data concerning new evidence for indigenous microfossils in CI meteorites, which may be the remains of extinct cometary cores. We discuss the dominant microbial communities of polar sea-ice, Antarctic ice sheet, and cryoconite environments as possible analogs for microbial ecosystems that may grow in sub-crustal pools or in ice/water films in comets.

Keywords: comets, cryoconite, extremophiles, Orgueil, carbonaceous chondrites, meteorites, cyanobacteria

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