MAGNETIC RECONNECTION IS A UNIVERSAL PLASMA PROCESS WHICH CONVERTS STORED MAGNETIC ENERGY INTO PARTICLE ENERGIES. THE MAIN OBJECTIVE OF THE MMS MISSION IS TO INVESTIGATE THE MICROPHYSICS OF RECONNECTION IN THE DIFFUSION REGION AT THE RECONNECTION SITE WITH EMPHASIS ON RECONNECTION OCCURRING AT THE DAYSIDE MAGNETOPAUSE AND IN THE MAGNETOTAIL. ALTHOUGH THE MAGNETOSHEATH REGION WAS NOT A FOCUS OF THE MMS PRIME MISSION THE DISCOVERIES OF RECONNECTION IN THE MAGNETOSHEATH OF BOTH TURBULENT AND NON-TURBULENT RECONNECTION INDICATE THAT THE MAGNETOSHEATH IS A NEW UNIQUE LABORATORY TO STUDY THIS PROCESS INSITU. THE MAGNETOSHEATH OFFERS MANY ADVANTAGES FOR RECONNECTION RESEARCH: A. MAGNETOSHEATH CURRENT SHEETS OFTEN CONVECT AT NEARLY CONSTANT SPEEDS ALLOWING THE DIRECT TRANSLATION OF THE OBSERVED TIME SERIES INTO SPATIAL PROFILES OF THE RECONNECTION LAYER WHICH ARE MUCH MORE DIFFICULT TO DEDUCE FROM MAGNETOPAUSE OR MAGNETOTAIL OBSERVATIONS BECAUSE OF THE HIGHLY UNSTEADY MOTION OF MAGNETOSPHERIC CURRENT SHEETS. B. THE MAGNETOSHEATH CONTAINS A LARGE NUMBER OF ION- AND ELECTRON-SCALE CURRENT SHEETS WITH A VARIETY OF BOUNDARY CONDITIONS. SOME OF THE BOUNDARY CONDITIONS (E.G. SYMMETRIC INFLOW CONDITIONS WITH LARGE GUIDE FIELDS) RARELY EXIST AT THE MAGNETOPAUSE OR IN THE MAGNETOTAIL. FURTHERMORE SINCE MAGNETOSHEATH CURRENT SHEETS CONVECT WITH THE MAGNETOSHEATH FLOWS THEIR BOUNDARY CONDITIONS ARE NOT EXPECTED TO CHANGE MUCH WITH TIME. THIS IS IN CONTRAST TO THE MAGNETOPAUSE WHERE VARIATIONS IN THE MAGNETOSHEATH IMPOSE TIME VARYING BOUNDARY CONDITIONS FOR MAGNETOPAUSE RECONNECTION. C. COMPARED TO THE SOLAR WIND WHERE SPACECRAFT CROSSINGS OF THE EXHAUSTS ARE USUALLY MORE THAN THOUSANDS OF ION INERTIAL LENGTHS DOWNSTREAM OF THE X-LINE CROSSINGS OF MAGNETOSHEATH RECONNECTION EVENTS ARE LIKELY TO TAKE PLACE CLOSER TO THE X-LINE BECAUSE RECONNECTION IS OFTEN INITIATED INSIDE THE MAGNETOSHEATH WHERE THE VOLUME OF SPACE IS SMALLER. HERE WE PROPOSE TO PERFORM A COMPREHENSIVE ANALYSIS OF ALREADY PUBLICLY AVAILABLE MMS LEVEL 2 HIGH-RESOLUTION BURST-MODE DATA COLLECTED IN THE MAGNETOSHEATH TO ESTABLISH THE OBSERVATIONAL FACTS ABOUT MAGNETOSHEATH RECONNECTION. SPECIFICALLY WE WILL FOCUS ON THE FOLLOWING SCIENCE QUESTIONS: 1. WHAT IS THE OCCURRENCE RATE OF RECONNECTION IN MAGNETOSHEATH CURRENT SHEETS? 2. WHAT ARE THE CONDITIONS FAVORABLE AND UNFAVORABLE FOR THE OCCURRENCE OF RECONNECTION IN MAGNETOSHEATH CURRENT SHEETS? 3. WHAT ARE THE PLASMA AND FIELD STRUCTURES OF THE RECONNECTION LAYER AND ITS BOUNDARIES AND HOW DO THEY DEPEND ON INFLOW CONDITIONS? MMS IS UNIQUELY CAPABLE OF FULLY ADDRESSING THESE QUESTIONS. WITH ITS ULTRA-FAST PLASMA MEASUREMENTS MMS IS THE ONLY MISSION THAT CAN ADEQUATELY RESOLVE ION AND ELECTRON-SCALE CURRENT SHEETS THAT ARE COMMON IN THE MAGNETOSHEATH ESPECIALLY DOWNSTREAM OF QUASIPARALLEL BOW SHOCKS WHERE THERE IS STRONG TURBULENCE. DURING THE JUST COMPLETED DAYSIDE PHASES 1A (SEPT 2015 MAR 2016) AND 1B (SEPT 2016 FEB 2017) THERE WERE HUNDREDS OF MAGNETOSHEATH CURRENT SHEETS CAPTURED IN BURST MODE WHICH WILL BE SUFFICIENT FOR THE PROPOSED STUDY. THE PROPERTIES OF RECONNECTION REVEALED BY THE PROPOSED WORK SHOULD BE UNIVERSAL. AS SUCH THE SCIENTIFIC OBJECTIVES OF THIS PROJECT ARE DIRECTLY ALIGNED WITH TWO OF THE SCIENCE GOALS IDENTIFIED IN THE HELIOPHYSICS DECADAL SURVEY: GOAL #3: DETERMINE THE INTERACTION OF THE SUN WITH THE SOLAR SYSTEM AND THE INTERSTELLAR MEDIUM. GOAL #4: DISCOVER AND CHARACTERIZE FUNDAMENTAL PROCESSES THAT OCCUR BOTH WITHIN THE HELIOSPHERE AND THROUGHOUT THE UNIVERSE. THE PROPOSAL ALSO ADDRESSES THE OVERARCHING GOAL OF THE MMS MISSION TO REVEAL THE STRUCTURE AND DYNAMICS OF THE ELECTRON-SCALE RECONNECTION LAYERS.