SCIENCE GOALS AND OBJECTIVES: SATURN AND JUPITER WHILE BOTH GAS GIANTS WITH RAPIDLY ROTATING MAGNETIC FIELDS POSSESS VERY DIFFERENT MAGNETOSPHERES. JUPITER WITH A PRIMARY PARTICLE SOURCE OF VOLCANIC ACTIVITY ON THE MOON IO HAS A PLASMA DOMINATED MAGNETOSPHERE EXHIBITING RELATIVELY SHORT IONIZATION LIFETIMES WITHIN ITS MAGNETOSPHERE. NEUTRAL PARTICLES HOWEVER DOMINATE IN SATURN S MAGNETOSPHERE BY TWO TO THREE ORDERS OF MAGNITUDE. DESPITE THE DIFFERENCES BETWEEN THESE TWO MAGNETOSPHERES THEY ALSO CONTAIN MANY SIMILARITIES. A BETTER UNDERSTANDING OF HOW AND WHY THESE SYSTEMS DEVELOPED INTO NEUTRAL VS. PLASMA DOMINATED SYSTEMS WILL PROVIDE A GREAT INSIGHT INTO FUNDAMENTAL MAGNETOSPHERIC DYNAMICS AND INTERACTIONS. FOR THIS RESEARCH OUR PRIMARY SCIENTIFIC GOAL IS TO PROVIDE AN UNDERSTANDING OF WHY JUPITER S MAGNETOSPHERE IS DOMINATED BY PLASMA WHILE SATURN S SYSTEM IS NEUTRAL PARTICLE DOMINATED. IN ORDER TO PROVIDE CLOSURE ON THIS SCIENTIFIC GOAL OUR OBJECTIVES ARE: 1) QUANTIFY THE DIFFERENCES BETWEEN THE TWO SYSTEMS IN TERMS OF INTERACTION PROCESS SOURCE LOCATIONS AND SOURCE STRENGTHS. 2) DETERMINE THE COMPARATIVE RELATIVE IMPORTANCE OF ALL INDIVIDUAL PARTICLE INTERACTION PROCESSES FOR THE JOVIAN AND SATURNIAN SYSTEMS 3) EXAMINE THE SENSITIVITY OF RELATIVE NEUTRAL VS. PLASMA COMPOSITION OF THESE ENVIRONMENTS TO CHANGES IN SOURCE LOCATIONS AND STRENGTHS. METHODOLOGYIN ORDER TO ACCOMPLISH THESE SCIENTIFIC GOALS AND OBJECTIVES WE PROPOSE AN EXHAUSTIVE STUDY OF THE JUPITER AND SATURN SYSTEMS. WE WILL APPLY OUR EXISTING VALIDATED 3-D MONTE CARLO NEUTRAL PARTICLE MODEL COUPLED WITH A PLASMA TRANSPORT MODEL TO SIMULATE THE MAGNETOSPHERIC REGION OF THESE TWO GIANT PLANETS. THESE COUPLED MODELS HAVE ALREADY BEEN USED TO MODEL THE SATURNIAN SYSTEM AND WORK HAS BEEN COMPLETED TO UPGRADE THE MODELS FOR THE JOVIAN SYSTEM. FOR THIS RESEARCH WE WILL COMPLETE MODIFYING OUR MODELS FOR SIMULATING JUPITER S MAGNETOSPHERE. WE WILL NEXT CONDUCT BASELINE MODE RUNS CONSTRAINED AND VALIDATED BY ALL AVAILABLE VOYAGER GALILEO CASSINI AND HST OBSERVATIONS TO ENSURE THE CURRENT SYSTEMS ARE ACCURATELY MODELED. WE WILL THEN RUN SIMULATION SCENARIOS WITH ONLY ONE INTERACTION PROCESS ACTIVE (I.E. PHOTOLYSIS ELECTRON-IMPACT CHARGE-EXCHANGE ION-NEUTRAL COLLISIONS AND NEUTRALNEUTRAL INTERACTIONS). ANALYSIS OF THESE RESULTS SHOULD ILLUSTRATE THE RELATIVE IMPORTANCE OF EACH PROCESS FOR DETERMINING PLASMA VS. NEUTRAL DOMINATED MAGNETOSPHERES. WE WILL NEXT CONDUCT A SERIES OF PARAMETRIC RUNS WHICH ADJUST THE PRIMARY SOURCE LOCATION AND STRENGTH FOR EACH MAGNETOSPHERE TO DETERMINE IF THESE VARIABLES CAN CHANGE THE RELATIVE PLASMA VS. NEUTRAL PARTICLE COMPOSITION. THE RESULTS OF THESE MODELS AND ANALYSIS SHOULD PROVIDE GREAT INSIGHT INTO THE FACTORS THAT GENERATED SUCH TWO DIVERGENT MAGNETOSPHERIC ENVIRONMENTS. RELEVANCE THE SCOPE OF THE SSW PROGRAM IS STATED AS SEEKING TO UNDERSTAND THE PROCESSES THAT OCCUR THROUGHOUT THE SOLAR SYSTEM AS WELL AS THOSE WHICH ARE SPECIFIC TO INDIVIDUAL OBJECTS AND SYSTEMS BUT INFORM OUR UNDERSTANDING OF FUNDAMENTAL PROCESSES AT WORK. THIS PROPOSED RESEARCH IS RELEVANT TO THE SSW PROGRAM IN THAT WE SEEK UNDERSTAND THE FUNDAMENTAL PROCESSES THAT DETERMINE THE RELATIVE MAGNETOSPHERIC POPULATIONS OF GAS GIANT PLANETS (JUPITER VS. SATURN) WITH IMPLICATIONS FOR OTHER MAGNETOSPHERES. MORE SPECIFICALLY THIS RESEARCH IS STRONGLY RELATED TO THE PLASMA ENVIRONMENTS RESEARCH CATEGORY AS IT EXAMINES THE GENERATION AND DISTRIBUTION NEUTRAL/PLASMA PARTICLES (SOURCES