OUR OBJECTIVE IS TO DEVELOP A SYSTEM OF CHEMICAL AND PHYSICAL CRITERIA THAT WILL ALLOW US TO EVALUATE THE VIABILITY OF PLANETARY ACCRETION MODELS. THE SCOPE OF THIS PROJECT IS TWOFOLD: (1) USE A MODEL OF THE HF-W ISOTOPIC SYSTEM IN LATE-STAGE ACCRETION OF PLANETARY BODIES TO DETERMINE WHICH N-BODY SIMULATIONS ARE ABLE TO REPRODUCE MEASURED VALUES FOR PLANETS THUS PROVIDING A WAY TO EVALUATE THE MOST LIKELY INITIAL CONDITIONS OF THE LATE ACCRETION PERIOD THAT FORMED OUR SOLAR SYSTEM; (2) EXAMINE THE UNIQUE HF-W SYSTEM RELATIONSHIP BETWEEN THE EARTH AND THE MOON ALLOWING US TO REFINE THE CONDITIONS OF THE MOON-FORMING IMPACT. THE ANALYSIS WILL EXPLORE THE EVOLUTION OF THE ISOTOPIC SYSTEM IN MODEL ANALOGS OF EARTH MOON AND MARS AND RECORD THEIR CORE AND MANTLE HISTORY. FOLLOWING THE ISOTOPIC RESULTS OF ACCRETION WILL ALLOW US TO DETERMINE THE RELATIVE IMPORTANCE OF LARGE STOCHASTIC IMPACT EVENTS IN THE FINAL MAKEUP OF PLANETS AND TO CATEGORIZE THE VARIOUS THEORIES OF PLANET FORMATION BY THEIR ABILITY TO PRODUCE BODIES THAT CAN MATCH SIGNATURES WE MEASURE TODAY. THE HF-W SYSTEM HAS BEEN USED TO RESEARCH CLASSICAL ACCRETION SCENARIOS WHICH ASSUME STATIONARY GIANT PLANET ORBITS ALLOWING TESTS OF RE-EQUILIBRATION LEVELS DURING COLLISIONS VIABILITY OF AVERAGE PLANET FORMATION TIMESCALES ISOTOPIC VARIABILITY IN LARGE AND SMALL SURVIVING OBJECTS AND THE INFLUENCE OF LATE GIANT IMPACTS ON THE FINAL ISOTOPIC MAKEUP OF A BODY. WE SEEK TO ANSWER THE QUESTION OF WHETHER RECENT PLANETARY FORMATION SCENARIOS CAN RE-CREATE THE PHYSICAL CONDITIONS NECESSARY TO FORM PLANETS WITH THE OBSERVED ISOTOPIC COMPOSITIONS. WE CAN USE OUR PROPOSED MODEL TO PROBE THE IMPACT RESULTS OF A RANGE OF POSSIBLE CORE/MANTLE EQUILIBRATION TYPES LEARNING HOW THE FAST ACCRETION OF THE GRAND TACK CREATES ISOTOPIC SIGNATURES DIFFERENT FROM THE SLOWER CLASSICAL MODEL. FURTHER BY LOOKING AT THE EQUILIBRATION HISTORY OF THE EARTH AND ITS PROTO-MOON IMPACTOR WE CAN SEEK CONDITIONS TO EXPLAIN THE GENERAL EARTH- MOON ISOTOPIC SIMILARITIES MEASURED IN THE PRESENT THUS IMPROVING OUR UNDERSTANDING OF HOW BOTH BODIES FORMED. WE WILL INVESTIGATE THE FORMATION AND EVOLUTION OF THE SOLAR SYSTEM AND PLANETARY BODIES AND SATELLITES BY MEANS OF HF-W ISOTOPIC ANALYSIS DURING LATE-STAGE ACCRETION OF THE TERRESTRIAL PLANETS. THIS PROJECT WILL SERVE THE SMD GOAL TO EXPLORE AND OBSERVE THE OBJECTS IN THE SOLAR SYSTEM TO UNDERSTAND HOW THEY FORMED AND EVOLVE BY USING MODEL ANALYSIS OF NEW ACCRETION SIMULATIONS THAT TRACK THE DYNAMICAL AND CHEMICAL EVOLUTION OF TERRESTRIAL BODIES. OUR RESEARCH IN APPLYING ISOTOPICALLY EVOLVED PLANETARY ANALOGS TO RECENT MOON-FORMING IMPACT MODELS WILL ALSO IMPROVE UNDERSTANDING OF THE HISTORY BEHIND THE EARTH AND MOON. WE WILL ALSO ADVANCE THE UNDERSTANDING OF HOW THE CHEMICAL PROCESSES IN THE SOLAR SYSTEM OPERATE INTERACT AND EVOLVE BY SIMULATING CORE AND MANTLE EQUILIBRATION DURING COLLISIONS ALLOWING US TO DETERMINE HOW METAL AND SILICATE EQUILIBRATION PLAYS A ROLE IN THE ISOTOPIC SYSTEMS OF PLANETARY ACCRETION.