SCIENCE GOALS&OBJECTIVES: MEASUREMENTS BY THE MERCURY SURFACE SPACE ENVIRONMENT GEOCHEMISTRY AND RANGING (MESSENGER) SPACECRAFT HAVE PROVIDED A WEALTH OF NEW INFORMATION ABOUT THE INTERIOR STRUCTURE AND EVOLUTION OF PLANET MERCURY. ONE OF THE BIGGEST SURPRISES FROM THE MESSENGER MISSION IS THE REVELATION OF MERCURY'S INTRINSIC MAGNETIC FIELD SEVERAL CHARACTERISTICS OF WHICH ARE UNIQUE ACROSS THE SOLAR SYSTEM. FIRST THE MAGNETIC FIELD IS STRONGLY NORTH-SOUTH ASYMMETRIC AND CAN BE CHARACTERIZED BY A DIPOLE THAT IS DISPLACED BY ~0.2 PLANET RADII TOWARD THE NORTH POLE AND TILTED LESS THAN 3 DEGREES FROM THE ROTATION AXIS [1]. IN ADDITION THE MAGNETIC FIELD IS UNUSUALLY WEAK COMPARED TO OTHER PLANETS WITH A MEAN SURFACE FIELD STRENGTH OF APPROXIMATELY 400 NT [1]. SIMILAR TO THE EARTH HOWEVER THE MAGNETIC FIELD APPEARS TO BE LONG-LIVED WITH EVIDENCE OF ANCIENT (~3.8 GA) REMNANT CRUSTAL MAGNETIZATION; THE STRENGTH OF THIS EARLY FIELD IS DIFFICULT TO CONSTRAIN WITH ESTIMATES RANGING FROM THE PRESENTDAY VALUE TO EARTH-LIKE VALUES OF ~50 MT [2]. IN THIS STUDY WE PROPOSE TO INVESTIGATE THE EVOLUTION OF MERCURY'S CORE AND DYNAMOGENERATED MAGNETIC FIELD USING INTERIOR EVOLUTION MODELS AND 3D NUMERICAL DYNAMO MODELS. METHODOLOGY: WE WILL USE AN ESTABLISHED INTERIOR MODEL OF MERCURY [3] THAT INCLUDES THE CONTRIBUTION DUE TO IRON SNOW IN COMBINATION WITH GEOPHYSICAL CONSTRAINTS (E.G. INNER CORE SIZE MOMENT OF INERTIA GLOBAL CONTRACTION ESTIMATES) FROM THE MESSENGER MISSION TO DETERMINE HOW THE CORE WOULD EVOLVE IN TIME FOR DIFFERENT INITIAL CORE SULFUR CONTENTS MANTLE PROPERTIES AND CRUSTAL THICKNESSES. CORE EVOLUTIONARY SEQUENCES WILL CONSIST OF A SERIES OF INTERIOR MODELS LINKED BY MANTLE THERMAL EVOLUTION MODELS WHICH ALLOWS ESTIMATION OF THE MASS FLUX DUE TO COMPOSITIONAL DIFFERENTIATION (E.G. INNER CORE GROWTH AND IRON SNOW) AND THE OHMIC DISSIPATION REQUIRED TO MAINTAIN A DYNAMO. WITH EXISTING SCALING LAWS THESE FLUX CALCULATIONS ALLOW US TO ASSESS THE SUSTAINABILITY OF A DYNAMO ESTIMATE ITS MAGNETIC FIELD STRENGTH AND MORPHOLOGY AND PREDICT THE CHARACTERISTICS OF THE CORE VELOCITY FIELD AS A FUNCTION OF TIME. WE WILL THEN MODEL THE 3D DYNAMO ACTION INSIDE MERCURY'S CORE USING THE STATE-OF-THE-ART GLOBAL NUMERICAL DYNAMO MODEL MAGIC. IN THESE 3D DYNAMO MODELS WE WILL IMPLEMENT DIFFERENT CORE STRATIFICATIONS AND BUOYANCY (MASS) FLUX PROFILES RESULTING FROM THE INTERIOR MODELS CALCULATED ALONG THE CORE EVOLUTION SEQUENCES. HERE WE WILL FOCUS ON THE EVOLUTION OF THE MAGNETIC FIELD STRENGTH AND MORPHOLOGY AS THE STRATIFICATION AND BUOYANCY FLUX IN THE CORE EVOLVES. THE RESULTS FROM THESE DYNAMO MODELS WILL BE USED TO FURTHER CONSTRAIN THE THERMAL COMPOSITIONAL AND MAGNETIC EVOLUTION OF MERCURY'S CORE. RELEVANCE OF THE PROPOSED RESEARCH: THE PROPOSED RESEARCH TO BETTER UNDERSTAND THE EVOLUTION OF MERCURY'S CORE AND MAGNETIC FIELD IS DIRECTLY RELEVANT TO THE SOLAR SYSTEM WORKINGS RESEARCH PROGRAM OBJECTIVES TO "DETERMINE THE INTERNAL STRUCTURE CHEMISTRY AND DYNAMICS OF SOLAR SYSTEM OBJECTS AND IDENTIFY AND UNDERSTAND THE PHYSICAL AND CHEMICAL PROCESSES THAT OCCUR WITHIN THESE STRUCTURES" AND TO "DETERMINE THE CONFIGURATION OF PLANETARY MAGNETIC FIELDS AND UNDERSTAND HOW AND WHY THEY ARE FORMED AND VARY THROUGH TIME". REFERENCES: [1] ANDERSON B. J. ET AL. (2011) SCIENCE 333 1859-1862. [2] JOHNSON C. L. ET AL. (2015) SCIENCE 348 892-895. [3] DUMBERRY M. AND RIVOLDINI A. (2015) ICARUS 248 254-268.