COLLISIONLESS MAGNETIC RECONNECTION IS A UNIVERSAL PLASMA PROCESS THAT CONVERTS MAGNETIC ENERGY INTO PARTICLE ENERGY. RECENTLY MMS HAS DISCOVERED A NEW REGION AND A NEW REGIME WHERE RECONNECTION TAKES PLACE NAMELY AT THE INTERFACE BETWEEN COLLIDING RECONNECTION JETS FROM TWO ACTIVE X-LINES INSIDE FLUX ROPE-LIKE STRUCTURES AT THE DAYSIDE MAGNETOPAUSE. OF THE FEW EVENTS THAT HAVE BEEN REPORTED SO FAR AN IMPORTANT COMMON FEATURE IS THAT RECONNECTION APPEARS TO BE IN THE RARELY SEEN MAGNETIC PILEUP REGIME INDICATING STRONGLY DRIVEN RECONNECTION WHERE THE CONVERGING (AND INFLOWING) JET SPEEDS MAY HAVE EXCEEDED THE RATE OF RECONNECTION IN THE INTERFACE CURRENT SHEET. ANOTHER IMPORTANT PROPERTY OF COLLIDING JET EVENTS IS THE OCCURRENCE OF DENSITY DEPLETION (INSTEAD OF DENSITY COMPRESSION) AND OPEN-ENDED FIELD TOPOLOGY ASSOCIATED WITH MAGNETIC FLUX PILEUP INDICATING SIGNIFICANT 3D EFFECTS. THE SCIENTIFIC OBJECTIVES OF THIS PROJECT ARE DIRECTLY ALIGNED WITH TWO OF THE HIGH-LEVEL SCIENCE GOALS IDENTIFIED IN THE HELIOPHYSICS DECADAL SURVEY: GOAL #2 - DETERMINE THE DYNAMICS AND COUPLING OF EARTH'S MAGNETOSPHERE IONOSPHERE AND ATMOSPHERE AND THEIR RESPONSE TO SOLAR AND TERRESTRIAL INPUTS. GOAL #4 - DISCOVER AND CHARACTERIZE FUNDAMENTAL PROCESSES THAT OCCUR BOTH WITHIN THE HELIOSPHERE AND THROUGHOUT THE UNIVERSE.