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Project Progress

In this grant period, Leshin and collaborators have concentrated on (1) modeling and publishing our data on the environmental history of carbonaceous chondrites and their associated pre-biotic organic molecules, and (2) obtaining new data in the exploration of the isotopic composition and distribution of carbon reservoirs on Mars.

Research conducted by Co-I Pizzarello this past year was largely devoted to the analyses of the Tagish Lake meteorite, a carbonaceous chondrite that fell in Canada in January of 2000. The meteorite’s atmospheric entry was exceptional in many regards: it was detected by a Department of Defense satellite, a first in observation of fireball and recovery of dust and meteorite, the landing was a frozen lake of a sparsely populated area of Canada, and the meteorite was recovered fairly soon by a local resident who, aware of its identity, carefully wrapped it and kept it frozen. Although the scientific interest for a meteorite so rare has been great, all the pristine samples remain the property of the finder to date. This laboratory received half of the only ten-gram piece that the finder has given so far for "destructive" analyses. The study of Tagish Lake organic content, which was published (Pizzarello et al., 2001; Pizzarello and Huang, 2002), characterized both the soluble organic suite and the insoluble macromolecular carbon of this meteorite.

Work by Pizzarello also included continuing pursuit of the molecular, chiral, and isotopic characterization of non-racemic amino acids in carbonaceous chondrites. New data relevant to the understanding of amino acid enantiomeric excesses in meteorites were submitted for publication. These new results appear to discount the hypothesis that UV circularly polarized irradiation during meteoritic compounds formation was the sole cause of their asymmetry and instead suggest more complex processes in which the meteorite mineral phases may have intervened.