This award in the Mars-Rock Special Research Opportunity activity supports investigation of mineralogical effects of microbial activity by Drs. William W. Barker and Jillian F. Banfield of the Geology Department, University of Wisconsin-Madison. The project is funded by the Office of Polar Programs, the Chemistry Division, and the MPS Office of Multidisciplinary Activities. Martian meteorite ALH84001 will be examined for mineralogical and textural evidence of biogeochemical silicate mineral alteration. The specific goals of the research are (1) to search for evidence of long-term interaction between low-temperature hydrous fluids and mineral surfaces by careful examination of surfaces for submicroscopic quantities of hydration products, such as clays; and (2) to examine the structure of the interface between the `nanofossils` and underlying minerals for evidence of polymer-mediated clay formation, dissolution features due to exposure to metabolic byproducts, and chemical signatures due to elemental concentrations associated with the presence of biopolymers. High resolution transmission electron microscopy (HRTEM) and energy-filtered transmission electron microscopy (EFTEM) of ion milled and ultramicrotomed meteorite samples will be used to examine the minerals at the crack surface for evidence of low-temperature alteration. Additional information will be gathered using high-resolution scaning electron microscopy (HRSEM) and other modern microscopy techniques capable of resolution to the atomic level. These methods will enable examination of the structure, composition, and mineralogy of the zone at the interface between the `microfossils` and underlying substrate. If ALH84001 contained microbes that lived in proximity to mineral surfaces, fine scale evidence for their interactions may be preserved at the microbe-mineral interface. Advanced physical and chemical methods will be used to detect alteration of the mineral surface. Terrestrial models for mineral-organism interaction will be used to distinguish biologically from inorganically-mediated alteration as a means of evaluating evidence of early Martian life.
