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C C Allen

Publications and source records attributed to C C Allen.

Life in the Ice

The current Martian surface environment is extremely hostile to any known form of life. The combination of subfreezing temperature, low atmospheric pressure and high ultraviolet flux, combined with desiccated and possibly oxidizing soil, could destroy even the hardiest microorganisms. The Viking biology experiments are generally interpreted to indicate that the surface of Mars is currently devoid of life and organic molecules at the part-per-billion level. Speculation on the possibility of extant or preserved microbial life on Mars thus centers on refuges in some manner protected from the current surface environment, either in space or time. Terrestrial analogs include hydrothermal systems, lakes, caves and subsurface aquifers as well as more clement conditions in the distant past. We are examining the evidence for microbiology in Earth's glaciated polar regions as analogs to the polar caps of Mars. This research concerns the detection of microorganisms or their preserved remains at the surface and within polar glacial ice.

C C Allen↗

Meridiani Planum Hematite Deposit: Potential for Preservation of Microfossils

Christensen et al., using data from the Mars Global Surveyor Thermal Emission Spectrometer (TES), have identified gray crystalline hematite in a 350 km by 750 km region near Meridiani Planum. The deposit corresponds closely to the low-albedo highlands unit sm, mapped as a wind-eroded, ancient, subaqueous sedimentary deposit. Christensen et al. interpreted the Meridiani Planum deposit to be an in-place, rock-stratigraphic sedimentary unit characterized by smooth, friable layers composed primarily of basaltic sediments with approximately 10 to 15% crystalline gray hematite. The Meridiani Planum hematite deposit has recently been designated as the prime landing site for one of the two Mars Exploration Rover (MER) spacecraft. The MER landings are scheduled for January, 2004. Christensen et al. discussed five possible mechanisms for the formation of this deposit: direct precipitation from standing, oxygenated, Fe-rich water; precipitation from Fe-rich hydrothermal fluids; low-temperature dissolution and precipitation through mobile groundwater leaching; surface weathering and coatings; thermal oxidation of magnetite-rich lavas. Four of these mechanisms involve the interactions of rock with water, and thus have implications in the search for evidence of microbial life.

C C Allen↗