SCIENCE GOALS AND OBJECTIVES: WE PROPOSE TO ATTACK MAINLY THROUGH NUMERICAL MODELING SOME MAJOR OUTSTANDING PROBLEMS IN THE CORE NUCLEATED ACCRETION THEORY OF THE FORMATION OF THE GIANT PLANETS IN THE SOLAR SYSTEM. THIS WORK WILL ACCOUNT FOR IMPORTANT PHYSICAL PROCESSES HERETOFORE NEGLECTED AND THEREBY PROVIDE A MUCH MORE REALISTIC MODEL FOR THE FORMATION AND EARLY EVOLUTION OF THE GIANT PLANETS. DURING THE EARLY STAGES OF GIANT PLANET ACCRETION WITH A ROCKY CORE OF AROUND AN EARTH MASS THE BASAL TEMPERATURE OF THE HYDROGEN ATMOSPHERE ABOVE THIS GROWING CORE CAN ALREADY EXCEED A FEW THOUSAND DEGREES SUFFICIENT TO ALLOW EVAPORATION OF ACCRETED PLANETESIMALS WITHIN THE ENVELOPE. THIS MAY AFFECT THE GROWTH OF THE GIANT PLANET PRIMARILY BY INCREASING THE MEAN MOLECULAR WEIGHT OF THE ENVELOPE (REDUCING THE PRESSURE SCALE HEIGHT) AND IT MAY ALSO PRODUCE A WIDER RANGE OF POSSIBLE OUTCOMES FOR GIANT PLANET FORMATION THAN THOSE PREVIOUSLY STUDIED. THE CONSEQUENCES MAY BE PARTIALLY PRESERVED THROUGHOUT SUBSEQUENT EVOLUTION AND INFLUENCE THE INTERNAL STRUCTURE OF THE GIANT PLANETS TODAY. TO STUDY THE EFFECTS OF THIS PROCESS WE WILL COMPUTE THE AMOUNT OF MIXING OF THE CONSTITUENTS WITHIN THE PLANETS DURING THEIR GROWTH. THIS ADDITIONAL PHYSICS WILL BE INCORPORATED INTO DETAILED NUMERICAL STUDIES OF THE CONCURRENT ACCRETION OF SOLIDS AND GAS INCLUDING AN IMPROVED TREATMENT OF INTERACTIONS OF THE GROWING PLANETS WITH THE SURROUNDING PROTOPLANETARY DISK. THE PROPOSED WORK WILL ADDRESS THE FOLLOWING QUESTIONS: HOW MUCH H AND HE WAS MIXED WITH MATERIAL FROM THE HEAVY ELEMENT "CORES'' OF THE PLANETS DURING THE FORMATION EPOCH? HOW MUCH PLANETESIMAL MATERIAL WAS DISSOLVED INTO THE H/HE ENVELOPE? HOW LONG DID JUPITER SATURN URANUS AND NEPTUNE TAKE TO FORM? WHAT WAS THE SOLIDS SURFACE DENSITY IN THE REGION OF THE PROTOPLANETARY DISK WHERE THESE PLANETS ACCRETED? DO JUPITER AND SATURN RETAIN MOST OF THE ANGULAR MOMENTUM OF THE CIRCUMPLANETARY SUBDISKS THROUGH WHICH MUCH OF THEIR MASS WAS ACCRETED OR DID THEY SHED MOST OF THIS ANGULAR MOMENTUM? METHODOLOGY: ACCRETION OF SOLIDS WILL BE MODELED USING THE PSI MULTIZONE CODE. THE INTERNAL STRUCTURE AND EVOLUTION OF EACH PLANET WILL BE MODELED WITH AN ADAPTED 1D STELLAR EVOLUTION CODE. GAS ACCRETION WILL BE FOLLOWED WITH A 3D HYDRODYNAMIC CODE WHEN APPROPRIATE. RELEVANCE TO NASA'S EMERGING WORLDS PROGRAM: OUR SIMULATIONS WILL PROVIDE A SUBSTANTIALLY IMPROVED PHYSICAL MODEL OF THE FORMATION OF THE FOUR GIANT PLANETS IN OUR SOLAR SYSTEM PARTICULARLY REGARDING THE MIXING OF LIGHT AND HEAVY COMPONENTS WITHIN THE PLANET AND IN OUR TREATMENT OF THE FINAL STAGES OF ACCRETION WHEN THE PLANETS' ULTIMATE MASSES AND HEAVY ELEMENTS CONTENT WERE DETERMINED. WE WILL DETERMINE WHETHER OR NOT A REALISTIC AMOUNT OF MIXING OF LIGHT GASES WITH HEAVY CONSTITUENTS WITHIN URANUS AND NEPTUNE CAN YIELD PLANET STRUCTURE MODELS THAT MATCH THE PLANETS' MEASURED GRAVITY FIELDS WITHOUT INVOKING SUPER-SOLAR ICE/ROCK RATIOS. THE INTERIOR STRUCTURES OF JUPITER AND SATURN THAT WE COMPUTE USING MIXING OF CONSTITUENTS WILL BE USEFUL TO INTERPRETING THE GRAVITY DATA SENT BACK BY THE JUNO AND CASSINI SOLSTICE MISSIONS. OUR PROPOSAL IS FOR RESEARCH THAT "AIMS TO ANSWER THE FUNDAMENTAL SCIENCE QUESTION OF HOW (THE LARGEST PLANETS WITHIN) THE SOLAR SYSTEM FORMED" AND "THEREBY IT PROVIDES CONTEXT FOR THE INTERPRETATION OF ... SOLAR SYSTEM OBSERVATIONS THAT ARE RELEVANT TO ITS FORMATION" (QUOTES FROM APPENDIX C.2 OF ROSES-15).