RELATIVISTIC ELECTRONS IN THE EARTH'S OUTER RADIATION BELT DISRUPT OPERATIONS AND DAMAGE THE FLEET OF ORBITAL SPACECRAFT THAT ARE OF INCREASINGLY VITAL COMMERCIAL AND NATIONAL SECURITY IMPORTANCE. THIS HIGH RISK EXISTS OVER A WIDE RANGE OF ORBITAL INCLINATIONS AND IT HAS BECOME MAGNIFIED AS NEW MORE EFFICIENT ORBITAL MANEUVERS EXPOSE SPACECRAFT TO THE MOST INTENSE REGIONS OF THE OUTER BELT FOR HUNDREDS OF DAYS. ONE OF THE MOST IMPORTANT DELETERIOUS EFFECTS OF RADIATION BELT ELECTRONS IS CHARGE ACCUMULATION THAT CAN LEAD TO ELECTROSTATIC DISCHARGE. MITIGATION OF THIS RISK IS POSSIBLE BY PLACING SATELLITES INTO A "SAFE-HOLD" DURING WHICH ALL NON-ESSENTIAL SYSTEMS ARE SHUT DOWN BUT EFFECTIVELY UTILIZING THIS SAFEGUARD REQUIRES PREDICTION CAPABILITY WITH SUFFICIENT FOREWARNING AND ACCURACY TO BE ACTIONABLE. IN ADDITION QUANTIFICATION OF THIS RISK MUST INVOLVE AN ACCURATE ATTRIBUTION OF THE OCCURRENCE OF ANOMALIES TO RELATIVISTIC ELECTRON EXPOSURE BUT DUE TO THE HYSTERETIC NATURE OF CHARGING THIS REQUIRES HIGHLY DETAILED DESCRIPTIONS OF THE LOCAL SPACECRAFT ENVIRONMENT PRECEDING THE ANOMALY. THE COMPLEXITY OF MANAGING THESE DAMAGING EFFECTS OF RADIATION IS EXACERBATED DUE TO THE STRONG VARIABILITY CHARACTERISTIC OF THE OUTER BELT: RELATIVISTIC ELECTRON INTENSITIES CAN VARY BY ORDERS OF MAGNITUDE ON TIMESCALES FROM MINUTES TO DAYS DUE TO THE SHIFTING BALANCE AMONG ACCELERATION AND LOSS PROCESSES. THEREFORE CHARACTERIZING AND PREDICTING THE VARIABILITY OF THE OUTER RADIATION BELT IS A FUNDAMENTAL CHALLENGE OF RESEARCH AND OPERATIONS IN THE NEAR-EARTH SPACE ENVIRONMENT. ADDRESSING THIS CHALLENGE IS THE OVERARCHING GOAL OF THE PROPOSED PROJECT. IT WILL BE ACCOMPLISHED AS THE CULMINATION OF THREE INTERLACED THRUSTS: (I) BUILD A PHYSICS-BASED MODEL WITH DATA-FLEXIBLE INGESTION CAPABILITY AND PREDICTIVE ACCURACY ON SPATIOTEMPORAL SCALES MOST RELEVANT TO OPERATIONAL RISK MANAGEMENT; (II) DEVELOP DATA PRODUCTS MOST RESPONSIVE TO OPERATIONAL NEEDS IN COLLABORATION WITH INDUSTRY PARTNERS; (III) PROVIDE AND ENSURE SUSTAINED ACCESS TO THIS MODEL TO THE BROAD STAKEHOLDER COMMUNITY VIA CCMC. OUR CURRENT RADIATION BELT MODEL USES A COMBINATION OF GLOBAL MAGNETOSPHERIC AND FULLY 3D MASSIVELY-PARALLEL RELATIVISTIC ELECTRON MACROPARTICLE SIMULATIONS. THE MODEL HAS A DEMONSTRATED CAPABILITY TO REPRODUCE SUB-HOUR VARIABILITY OBSERVED BY THE VAN ALLEN PROBES DURING GEOMAGNETIC STORMS USING ONLY SOLAR WIND INPUT. IN THE PROPOSED PROJECT WE WILL BUILD UPON THE PRIOR SUCCESS AND AUGMENT OUR PHYSICS-BASED MODEL BY INCORPORATING THE CAPABILITY TO INGEST SPACECRAFT MEASUREMENTS OF RELATIVISTIC ELECTRON INTENSITY AT ARBITRARY LOCATIONS AND TEMPORAL CADENCE. TO THIS END WE WILL UTILIZE OUR NEW STATE-OF-THE-ART MHD CODE GAMERA WHICH IS A REINVENTION OF THE HIGH-HERITAGE LFM MODEL COUPLED WITH THE RICE CONVECTION MODEL OF THE RING CURRENT TO CREATE AN UNPRECEDENTED TOOL TO STUDY MESOSCALE ELECTRODYNAMICS IN THE INNER MAGNETOSPHERE. CONCURRENTLY TO BUILDING THIS NEXT-GENERATION RADIATION BELT MODELING CAPABILITY WE WILL ENSURE THE ACCESS AND RELEVANCE OF THESE MODELING TOOLS TO BOTH SIDES OF THE RESEARCH-OPERATIONS DIVIDE. WORKING WITH INDUSTRY PARTNERS WE WILL IDENTIFY OPERATIONS-RELEVANT DATA PRODUCTS WITH A PARTICULAR EMPHASIS ON ADDRESSING UNCERTAINTY REGARDING THE ROLE OF SPACE WEATHER IN ANOMALIES. BY MAKING THESE TOOLS AND DATA PRODUCTS AVAILABLE THROUGH NASA'S CCMC WE WILL LEVERAGE THEIR SKILLS AND EXPERTISE TO ENGAGE THE WIDEST POSSIBLE SEGMENT OF THE STAKEHOLDER COMMUNITY. THE PROPOSED WORK IS DIRECTLY RELEVANT TO THE FOCUS AREA OF THE HSW-O2R PROGRAM ELEMENT BY IMPROVING SPECIFICATIONS AND/OR FORECASTS OF THE ENERGETIC PARTICLE AND PLASMA CONDITIONS ENCOUNTERED BY SPACECRAFT WITHIN EARTH'S MAGNETOSPHERE.