WE PROPOSE TO INVESTIGATE HOW COLD MAGNETOSPHERIC ION POPULATIONS ARE HEATED AND ACCELERATED ONCE THESE IONS ENCOUNTER THE MAGNETOPAUSE AND ARE ENTRAINED IN MAGNETOPAUSE BOUNDARY LAYERS. TO STUDY THE EVOLUTION OF COLD ION POPULATIONS AT THE DAYSIDE MAGNETOPAUSE WE WILL UTILIZE A TIME PERIOD WITH A VERY UNIQUE "STRING-OF-PEARLS" CONFIGURATION OF THE MAGNETOSPHERIC MULTISCALE (MMS) SPACECRAFT CONSTELLATION. THIS CONFIGURATION ALLOWS FOR SIMULTANEOUS MEASUREMENTS OF THE COLD ION POPULATIONS WITHIN DIFFERENT REGIONS OF THE MAGNETOSPHERE INNER MAGNETOPAUSE BOUNDARY LAYER AND RECONNECTION EXHAUST. WE WILL BE USING MEASUREMENTS OF BOTH THE COLD AND HEAVY ION DISTRIBUTIONS IN THESE DIFFERENT REGIONS OVER MULTIPLE MAGNETOPAUSE CROSSINGS WHEN MMS IS LIKELY CLOSE TO OR WITHIN THE ION DIFFUSION REGION AND WHEN MMS IS FURTHER DOWNSTREAM OF A RECONNECTION SITE. USING MULTIPLE CROSSINGS AT VARYING DISTANCES FROM A RECONNECTION SITE WE AIM TO DETERMINE THE EXTENT OF HEATING ACCELERATION AND PITCH ANGLE SCATTERING AT THESE DIFFERENT LOCATIONS IN ORDER TO ASSESS THE RELATIVE IMPORTANCE OF DIFFERENT MECHANISMS RESPONSIBLE FOR CHANGES IN THE ION DISTRIBUTIONS SUCH AS E B DRIFT POTENTIAL DROPS ACROSS THE SEPARATRICES NON-ADIABATIC ACCELERATION AND RESONANT INTERACTIONS WITH WAVES. HOW THE COLD AND HEAVY MAGNETOSPHERIC ION POPULATIONS AFFECT AND/OR ARE AFFECTED BY RECONNECTION AT THE DAYSIDE MAGNETOPAUSE IS STILL NOT WELL UNDERSTOOD BUT CAN BE FURTHER ADDRESSED BY THE CAPABILITIES OF MMS AND THE ADVANTAGEOUS CONFIGURATION OF MMS DURING RECENT DAYSIDE ORBITS.