MODELS OF THE THERMAL EVOLUTION OF CHONDRITIC AND ACHONDRITIC METEORITE PARENT ASTEROIDS ARE PREDICATED ON GEOTHERMOMETRIC ESTIMATES OF PEAK TEMPERATURES ACHIEVED ON THOSE BODIES. THERMAL MODELS INFORM OUR UNDERSTANDING OF METAMORPHISM AND DIFFERENTIATION ON METEORITE PARENT BODIES AND THE PLANETESIMALS THAT ACCRETED TO FORM THE PLANETS. HOWEVER GEOTHERMOMETERS USED TO CONSTRAIN THE THERMAL EVOLUTION OF ASTEROIDS TYPICALLY RECORD BLOCKING TEMPERATURES DURING COOLING RATHER THAN PEAK OR MAGMATIC TEMPERATURES. RECENTLY A RARE EARTH ELEMENT (REE)-IN-TWO PYROXENE THERMOMETER WAS DEVELOPED WHICH RELIES ON THE RELATIVELY SLOW DIFFUSIVE EXCHANGE OF REES BETWEEN COEXISTING PYROXENES AND HAS BEEN SHOWN TO RECORD NEAR-PEAK OR MAGMATIC TEMPERATURES FOR SAMPLES FROM A VARIETY OF GEOLOGIC SETTINGS IN EARTH'S MANTLE AND CRUST. APPLICATIONS OF THE REE-IN-TWO PYROXENE THERMOMETER TO METEORITES ARE EXTREMELY LIMITED. A PRELIMINARY PROOF-OF-CONCEPT STUDY PRESENTED HERE SUGGESTS THE LL CHONDRITE PARENT BODY COOLED AT A RATE>1 DEGREE/Y FROM A TEMPERATURE OF ~950 DEGREES IMPLYING THAT IT WAS CATASTROPHICALLY FRAGMENTED AND QUENCHED FROM ITS PEAK METAMORPHIC TEMPERATURE. IN CONTRAST TO OUR RESULTS COOLING RATES ESTIMATED USING METHODS SENSITIVE TO LOW TEMPERATURE COOLING (I.E. AT TEMPERATURES<500 DEGREES) ARE ORDERS OF MAGNITUDE SLOWER SUGGESTING THAT SUBSEQUENT TO BREAKUP THE LL CHONDRITE PARENT BODY REACCRETED AND THEN COOLED SLOWLY WHILE 26AL OR ANOTHER HEAT SOURCE WAS STILL ACTIVE. THIS PRELIMINARY RESULT DEMONSTRATES THE POWER OF THE REE-IN-TWO PYROXENE THERMOMETER TO UNRAVEL HIGH TEMPERATURE COOLING HISTORIES OF METEORITES BREATHING NEW LIFE INTO SAMPLES STUDIED EXTENSIVELY IN THE PAST. SCIENCE GOALS AND OBJECTIVES WE PROPOSE TO INVESTIGATE THE THERMAL HISTORY OF ORDINARY CHONDRITES WINONAITES UREILITES ACAPULCOITES AND CUMULATE EUCRITES USING THE REE-IN-TWO PYROXENE THERMOMETER TO USE THE TEMPERATURES TO ESTIMATE COOLING RATES OF THE SAMPLES THROUGH LOW AND HIGH TEMPERATURE INTERVALS AND TO DEVELOP NEW MODELS OF THE THERMAL EVOLUTION OF ASTEROIDS. OUR OBJECTIVES ARE TO PLACE CONSTRAINTS ON FUNDAMENTAL ASPECTS OF ASTEROIDAL EVOLUTION INCLUDING (BUT NOT LIMITED TO) (1) HEATING AND COOLING HISTORIES AND MECHANISMS (2) PLANETESIMAL BREAKUP AND REASSEMBLY AND ITS INFLUENCE ON SUBSEQUENT ASTEROIDAL EVOLUTION (3) CONDITIONS OF PARTIAL MELTING AND DIFFERENTIATION (4) CONDITIONS AND MECHANISMS OF CRUSTAL FORMATION. RELEVANCE THIS PROPOSAL CONTRIBUTES DIRECTLY TO THE OVERARCHING SOLAR SYSTEM WORKINGS PROGRAM GOAL OF UNDERSTANDING PROCESSES THAT OCCUR THROUGHOUT THE SOLAR SYSTEM. IT ADDRESSES THE DETERMINATION OF THE INTERNAL STRUCTURE CHEMISTRY AND DYNAMICS OF SOLAR SYSTEM OBJECTS (SPECIFICALLY ASTEROIDS) AND INFORMS OUR UNDERSTANDING OF THE FUNDAMENTAL PHYSICAL AND CHEMICAL PROCESSES THAT OCCUR WITHIN THESE STRUCTURES. SPECIFICALLY THE PROPOSED WORK WILL IMPROVE OUR UNDERSTANDING OF THE THERMAL STRUCTURE OF ASTEROIDS SUBSEQUENT DIFFERENTIATION LEADING TO THE FORMATION AND EVOLUTION OF ASTEROIDAL MANTLES AND CORES PARTIAL MELTING IN ASTEROIDAL INTERIORS THAT GENERATES SURFACE VOLCANISM AND MODIFICATION OF ASTEROIDAL SURFACES AND INTERIORS BY CATASTROPHIC FRAGMENTATION.