IF AND HOW GALAXIES REIONIZED THE UNIVERSE REMAINS AN OPEN QUESTION. TO PROVIDE A DEFINITIVE ANSWER TO THIS FUNDAMENTAL QUESTION REQUIRES A ROBUST UNDERSTANDING OF A KEY PARAMETER THE FRACTION OF IONIZING PHOTONS ESCAPING FROM GALAXIES AT THE EPOCH OF REIONIZATION (EOR) INTO THE INTERGALACTIC MEDIUM FESC. FESC IS EXTREMELY DIFFICULT TO MEASURE DIRECTLY FOR GALAXIES DURING REIONIZATION. THEORETICAL DETERMINATIONS OF FESC ARE INDISPENSABLE BUT CURRENTLY SPAN A RANGE WIDER THAN REQUIRED TO ANSWER THE QUESTION ABOVE. THIS PROPOSED PROGRAM WILL CARRY OUT A COMPREHENSIVE STUDY WITH THE AIM TO NAIL DOWN FESC. IN THIS RESEARCH PROGRAM WE PROPOSE TO PERFORM TWO IMPORTANT TASKS THAT ARE REQUIRED TO FIRM UP A ROBUST UNDERSTANDING AND CONSENSUS OF FESC OF GALAXIES AT EOR. FIRST WE WILL CARRY OUT HIGH RESOLUTION RADIATION HYDRODYNAMIC SIMULATIONS WITH A MOST COMPREHENSIVE PHYSICAL TREATMENT. IN ADDITION TO ADVANCED IMPLEMENTATION OF SUPERNOVA FEEDBACK WE WILL INCLUDE POPULATION III TO II TRANSITION RUNAWAY O/B STARS DELAYED IONIZATION SOURCES AND SUPERNOVAE DUE TO BINARY EVOLUTION INDUCED STELLAR MERGER PRODUCTS AND IMPORTANTLY DELAYED IONIZATION SOURCES DUE TO PRIMARIES TURNED STRIPPED NAKED HOT HELIUM CORES THROUGH BINARY EVOLUTION THAT HAS NOT BEEN CONSIDERED SO FAR AND MAY POTENTIALLY BE THE MOST IMPORTANT CONTRIBUTOR TO ESCAPED IONIZING PHOTONS. SECOND SINCE FESC MAY NOT BE DIRECTLY OBSERVED AT EOR WE WILL CARRY OUT THE FIRST MULTIFACETED DIAGNOSTIC VERIFICATION AND CALIBRATION STUDY BY INVESTIGATING RELATIONS BETWEEN FESC WITH OBSERVABLES OF GALAXIES. THIS PROGRAM DIRECTLY SUPPORTS MAJOR NASA MISSIONS (HST JWST AND OTHERS).