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SUMMARY THE COMPOSITIONS OF THE TERRESTRIAL PLANETS WERE SHAPED BY A VARIETY OF PROCESSES IN THE EARLY SOLAR SYSTEM INCLUDING ACCRETION CORE FORMATION AND A LATE VENEER. N-BODY SIMULATIONS OF TERRESTRIAL PLANET ACCRETION PROVIDE DIFFERENT SCENARIOS FOR HOW WHERE AND WHEN THE TERRESTRIAL PLANETS GREW. HOWEVER THERE HAS BEEN LIMITED WORK RELATING THESE SIMULATIONS TO THE RESULTING PLANETARY CHEMISTRY. WE PROPOSE TO INCORPORATE MODELS OF RU/MO ISOTOPE SYSTEMATICS AND HF/W ISOTOPIC EVOLUTION INTO PRE-EXISTING N-BODY SIMULATIONS TO TEST WHICH OF THE VARIOUS ACCRETION SCENARIOS ARE MOST REALISTIC. RU IS HIGHLY SIDEROPHILE SUCH THAT THE RU ISOTOPIC COMPOSITION OF A PLANET'S MANTLE IS PRIMARILY CONTROLLED BY LATE-ACCRETED MATERIAL; CONVERSELY MO IS ONLY MODERATELY SIDEROPHILE SO THE MANTLE MO ISOTOPIC COMPOSITION REFLECTS MATERIAL ACCRETED THROUGHOUT THE PLANET'S FORMATION. THE EARTH AND METEORITES LIE ON THE SAME RU-MO ISOTOPIC TREND INDICATING THAT THE EARTH'S MAIN PHASE OF ACCRETION AND ITS LATE VENEER LIKELY HAVE THE SAME ISOTOPIC PROVENANCE. TO BETTER UNDERSTAND THIS OBSERVATIONAL CONSTRAINT WE WILL MODEL THE EVOLUTION OF RU AND MO ISOTOPES IN THE TERRESTRIAL PLANETS BASED ON N-BODY SIMULATIONS. THIS MODELING WILL PROVIDE INFORMATION ABOUT THE SPATIAL EXTENT OF AN ISOTOPICALLY HOMOGENOUS REGION IN THE INNER DISK AND HOW IT DEPENDS ON THE ORBITS OF JUPITER AND SATURN. THIS WORK WILL ALSO ALLOW US TO MAKE A TESTABLE PREDICTION FOR THE RU/MO ISOTOPIC COMPOSITION OF MARS.

$299,972FY2017National Aeronautics and Space AdministrationNASA

President And Fellows Of Harvard College

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