MAGNETIC RECONNECTION IS EFFECTIVELY IDENTIFIED OBSERVATIONALLY VIA THE DETECTION OF FAST OUTFLOW JETS CAUSED BY THE CONVERSION OF MAGNETIC ENERGY TO KINETIC ENERGY. INDEED RECONNECTION JETS ARE AMONG THE MOST DIAGNOSED FEATURES IN SPACE PLASMAS AND A LARGE DATABASE OF SUCH ENCOUNTERS IS AVAILABLE FROM MANY MISSIONS. WE FOCUS HERE ON THE EXISTING DATA FROM MMS IN THE MAGNETOPAUSE AND IN THE TAIL AS WELL AS DATA FROM PREVIOUS MISSIONS. TAKEN TOGETHER THESE ENCOUNTERS FORM THE BASIS FOR A DETAILED INVESTIGATION DESIGNED TO ARRIVE AT A CLEAR UNDERSTANDING OF THE ROLE OF RECONNECTION IN THE EVOLUTION OF MAGNETOSPHERIC PLASMAS. THE PROPOSED RESEARCH EFFORT FOCUS ON TWO DISTINCT RECONNECTION SCENARIOS: ISOLATED RECONNECTION SITES WHERE OUTFLOW JETS PROPAGATE INTO AND INTERACT WITH THE PRE-EXISTING PLASMA TO FORM FRONTS AND MULTIPLE RECONNECTIONS SITES WHERE THE JETS INTERACT WITH ONE ANOTHER. THE GOAL OF THE PROPOSED RESEARCH IS TO INVESTIGATE WHAT WAVES AND INSTABILITIES DEVELOP IN THESE OUTFLOWS. IN THE OUTFLOWS WE OBSERVE TEMPERATURE ANISOTROPIES VELOCITY SHEARS INTERPENETRATING BEAMS DENSITY AND PRESSURE GRADIENTS THE PRESENCE OF UNFAVORABLE MAGNETIC FIELD LINE CURVATURE. ALL THESE SOURCES OF FREE ENERGY HAVE BEEN OBSERVED TO CAUSE INSTABILITIES. THE NON-LINEAR DEVELOPMENT OF THESE WAVES LEADS TO A STRONG MODIFICATION OF THE PARTICLE DISTRIBUTION FUNCTION LEADING TO PARTICLE ACCELERATION AND HEATING AS WELL AS THE INSURGENCE OF STRONG POYNTING FLUXES CARRYING ELECTROMAGNETIC ENERGY. IN THESE CONDITIONS THE OUTFLOWS BECOME A POWERHOUSE FOR ENERGY EXCHANGE FOR THE FORMATION OF SECONDARY RECONNECTION SITES AND THE ONSET OF A POSSIBLY TURBULENT CASCADE. THE QUESTION IS THEN HOW IMPORTANT ARE THESE PHENOMENON IN TERMS OF THEIR IMPACT ON THE DYNAMICS OF SUBSTORMS AND THEIR IMPACT CLOSER TO EARTH? THE ANSWER TO THESE QUESTION LIES IN THE ANALYSIS OF THE WAVE SPECTRA OF THE PARTICLE DISTRIBUTION FUNCTIONS AND OF THE ENERGY TRANSPORT FLUXES (POYNTING HEAT ENTHALPY) FOR EACH SPECIES AND FOR THE ELECTROMAGNETIC FIELDS. THESE CAN BE MEASURED IN SITU AT VARIOUS DISTANCES FROM THE RECONNECTION SITE (INTENDED HERE AS THE LOCI WHERE FIELD LINES BREAK AND RECONNECT OFTEN LOOSELY CALLED X-POINTS). FORM A DATABASE OF DIFFERENT CROSSING AND FROM DIFFERENT SPACECRAFTS AT DIFFERENT LOCATIONS FOR THE SAME CROSSING INFORMATION CAN BE DERIVED ON THE ENERGY FLUXES AND CAN BE PUT IN CONTEXT OF OUR UNDERSTANDING OF RECONNECTION IN THE MAGNETOSPHERE. THIS ANSWER WILL DEPEND DRASTICALLY ON THE GLOBAL CONTEXT OF RECONNECTION FOR EACH DIFFERENT CROSSING. TO ADDRESS THESE SCIENCE QUESTIONS AND ACHIEVE OUR GOALS WE WILL EMPLOY THE FOLLOWING METHODOLOGY EMPLOYING A COMBINATION OF STATE-OF-THE-ART COMPUTER SIMULATIONS AND DATA ANALYSIS: MMS (BUT TO A LESSER DEGREE ALSO PREVIOUS MISSIONS) ALLOW US TO CONSTRUCT SIMULATIONS INITIALIZED WITH THE LOCALLY OBSERVED PARTICLE DISTRIBUTION FUNCTIONS AND WITH A MEAN CONFIGURATION OF THE PLASMA AND FIELDS INDUCED BY THE DATA. WE CAN THEN OBTAIN FROM SIMULATION THE PLASMA EVOLUTION UNDER THOSE CONDITIONS AND COMPARE DIRECTLY VIRTUAL MEASURES IN THE SIMULATED PLASMA WITH REAL DIAGNOSTICS FROM THE MISSIONS. THE NOVELTY IS THE USE OF OBSERVATIONAL DATA TO SETUP THE SIMULATION AND THE DEVELOPMENT OF SYNTHETIC MEASUREMENTS FROM THE SIMULATION TO REPLICATE THE OBSERVED MEASUREMENTS. THE LOOP STARTING WITH DATA LEADING TO DATA-DRIVEN SIMULATIONS AND PRODUCING SYNTHETIC OBSERVATIONS WILL BE CLOSED BY THE DIRECT COMPARISON OF REAL OBSERVATIONS AND SYNTHETIC OBSERVATION USING THEORY MODELS CAPABLE OF PREDICTING THE WAVES AND INSTABILITY IN THE SIMULATIONS AND IN THE OBSERVED NATURAL PLASMA. BY ADDRESSING THE STATED SCIENCE QUESTIONS USING THE STATED METHODOLOGY THE PRESENT PROPOSAL AIMS CENTRALLY AT GOAL #4 OF THE HELIOSPHERIC DECADAL SURVEY GOAL: MAGNETIC RECONNECTION IS A FUNDAMENTAL PLASMA PROCESS THAT OCCURS BOTH WITHIN THE HELIOSPHERE AND THROUGHOUT THE UNIVERSE.