Isotopic, elemental, and structural analysis of presolar matter

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Presolar grains, or grains originating prior to the formation of the Sun, have been found in primitive meteorites, interplanetary dust particles, and in the cometary samples collected by the NASA mission Stardust. They are identified by their highly anomalous isotopic composition, which is indicative of their condensation around final stage stars, which eject such material in giant explosions or during increased stellar winds. Modern analytical tools permit the investigation of individual presolar grains and their constituents, which reveal evidence of the processes occurring within stars. We intend to study in situ with TOF-SIMS, TEM, and NanoSIMS the chemistry and structure of presolar grains in the various types of primitive Solar System samples. Our analyses will focus on how presolar grains are incorporated into early Solar System materials and their survival to present time. In particular, samples from NASA's Stardust mission to comet Wild 2, the first extraterrestrial solid samples returned for laboratory analysis by a space mission since the lunar missions, are essential in this study. We will obtain the elemental, isotopic, and mineralogical composition of presolar grains in order to identify the stellar sources of the starting material of the Solar System, and to delineate the stellar, interstellar, and protoplanetary processes in which cometary grains may be involved.