CURRENT AND FUTURE MISSION TARGETS SHOW EVIDENCE OF HAVING HOSTED LIQUID WATER WITH COMPLEX ORGANIC AND INORGANIC CHEMISTRIES AT SOME POINT IN THEIR HISTORY. WE WISH TO CHARACTERIZE THE TIMING AND NATURE OF CHEMICAL EVOLUTION OCCURRING DURING THE EARLY HISTORY OF SUCH SOLAR SYSTEM BODIES BY CARRYING OUT A DETAILED PETROGRAPHIC AND ISOTOPIC STUDY OF THEIR CLOSEST ANALOGUES THE CARBONACEOUS CHONDRITE METEORITES. WE PROPOSE TO EXAMINE CARBONATE MINERALS WITHIN THESE METEORITES USING THE 53MN-53CR CHRONOMETER TO ESTABLISH FORMATION TIMESCALES AND TRACK THE CHEMICAL AND ISOTOPIC EVOLUTION OF THE PRECIPITATING FLUIDS VIA THE CARBON AND OXYGEN STABLE ISOTOPE COMPOSITIONS OF THE SECONDARY MINERALS PRODUCED. WE WILL TAKE ADVANTAGE OF RECENT ADVANCES IN ANALYTICAL PROCEDURES FOR CARBONATE ANALYSIS BY ION PROBE TO CONDUCT ACCURATE HIGH-PRECISION IN-SITU MEASUREMENTS WHILE PRESERVING THE COMPLEX PETROLOGIC CONTEXT OF THE TARGET MINERALS. BY COMBINING OXYGEN AND CARBON ISOTOPIC COMPOSITIONS WITH FORMATION AGES BASED ON THE SHORT-LIVED MN-CR SYSTEM AND THE DETAILED INFORMATION PROVIDED BY THE PETROLOGIC CONTEXT OF THE CARBONATES WE WILL TRACK THE INFLUENCE OF VARIOUS FLUID AND CHEMICAL RESERVOIRS AND REACTIONS IN TIME. WE HAVE SELECTED SAMPLES WHICH SPAN THE FULL RANGE OF ALTERATION EXTENT IN THE CM AND CI METEORITES TO CHARACTERIZE A WIDE DIVERSITY OF FLUID ALTERATION ENVIRONMENTS. USING THESE RESULTS WE WILL CONSTRUCT AND EVALUATE NUMERICAL MODELS OF PLANETESIMAL EVOLUTION TO EXAMINE THE SETTINGS IN WHICH THESE AQUEOUS ALTERATION PROCESSES OPERATED IN THE EARLY SOLAR SYSTEM. SUCH A STUDY IS RELEVANT TO NASA'S STRATEGIC PLAN AND PLANETARY SCIENCE GOALS BECAUSE OF ITS FOCUS ON USING LABORATORY ANALYSES OF EXTRATERRESTRIAL SAMPLES TO CONSTRAIN THE TIMESCALES OF THE EVOLUTION OF ORGANIC-RICH FLUIDS PERTINENT TO STUDIES OF PREBIOTIC CHEMISTRY AND ITS INTENT TO INVESTIGATE CHEMICAL AND PHYSICAL PROCESSES OCCURRING IN THE ON EARLY SOLAR SYSTEM PLANETESIMALS