PROPOSE TO CONTINUE THE DEVELOPMENT OF THE GAMMA-RAY IMAGER/POLARIMETER FOR SOLAR FLARES (GRIPS) THE NEXT-GENERATION INSTRUMENT FOR HIGH-ENERGY SOLAR OBSERVATIONS. GRIPS WILL PROVIDE A NEAR-OPTIMAL COMBINATION OF HIGH-RESOLUTION IMAGING SPECTROSCOPY AND POLARIMETRY OF SOLAR-FLARE GAMMA-RAY/HARD X-RAY EMISSIONS FROM ~20 KEV TO>~10 MEV USING AN ARRAY OF 3D POSITION-SENSITIVE GERMANIUM DETECTORS (3D-GEDS) THAT ALLOWS THE POSITION AND ENERGY DEPOSITION OF EVERY PHOTON INTERACTION TO BE RECORDED INDIVIDUALLY TOGETHER WITH A MULTI-PITCH ROTATING MODULATOR (MPRM) PLACED 8 METERS AWAY TO PROVIDE A FULL-SUN FIELD-OFVIEWAND ANGULAR RESOLUTION (12.5-ARCSEC FWHM AT GAMMA-RAY ENERGIES) SUFFICIENT TO SEPARATE THE FOOTPOINTS OF 2.2 MEV SOURCES FOR ALMOST ALL FLARES. A PARTIAL VERSION OF GRIPS IS PRESENTLY BEING PREPARED FOR ITS ENGINEERING TEST BALLOON FLIGHT IN SEPTEMBER 2012. HERE WE PROPOSE TO COMPLETE THE DEVELOPMENT OF A FULL-UP GRIPS AND FLY IT ON LONG (OR ULTRA-LONG) DURATION BALLOON FLIGHTS FROM ANTARCTICA TO STUDY HIGH ENERGY PARTICLE ACCELERATION IN SOLAR FLARES. GRIPS THUS ADDRESSES THE NASA GOAL OF "UNDERSTANDING THE SUN AND ITS EFFECTS ON EARTH AND THE SOLAR SYSTEM" THROUGH STUDY OF "POWERFUL FLARES AND CORONAL MASS EJECTIONS " IN PARTICULAR THE FLARE ENERGYRELEASE AND THE ACCELERATION OF PARTICLES.