THE EARLY SOLAR SYSTEM AND ITS PRECURSORS SCIENCE GOALS AND OBJECTIVES. THE GENERAL THEME OF THE PROPOSED WORK IS TO BETTER UNDERSTAND THE NATURE AND TIMING OF MIXING AND NEBULAR PROCESSING IN THE EARLY SOLAR SYSTEM THE ULTIMATE SOURCES OF DUST IN THE SOLAR NEBULA STELLAR NUCLEOSYNTHESIS AND THE CHRONOLOGY OF THE FIRST FEW MILLION YEARS OF SOLAR SYSTEM HISTORY. THESE GOALS ARE TO BE ACCOMPLISHED BY MEASUREMENTS OF CHEMICAL AND ISOTOPIC COMPOSITIONS OF A VARIETY OF METEORITE SAMPLES SUCH AS CAIS CHONDRULES IDPS PRESOLAR GRAINS AND DIFFERENTIATED METEORITES. (1) THERE ARE A NUMBER OF UNRESOLVED ISSUES IN EARLY SOLAR SYSTEM CHRONOLOGY INCLUDING THE LEVELS OF SHORT-LIVED 41CA 60FE AND 92NB. BY TAKING ADVANTAGE OF THE HIGH SENSITIVITY AND SELECTIVITY OF LASER RESONANCE IONIZATION MASS SPECTROMETRY (RIMS) WE PLAN TO RESOLVE THESE ISSUES THROUGH ANALYSES OF CAIS AND CHONDRULES. (2) THE 182HF-182W SYSTEM HAS BEEN VERY SUCCESSFUL FOR EARLY SOLAR SYSTEM CHRONOLOGY BUT NEARLY ALL PREVIOUS STUDIES HAVE RELIED ON HIGH PRECISION W ISOTOPIC MEASUREMENTS ON BULK SAMPLES AND MINERAL SEPARATES. WE WILL USE THE HIGH SENSITIVITY AND SELECTIVITY OF RIMS TO DO IN SITU 182HF-182W DATING OF CAIS AND ZIRCONS FROM DIFFERENTIATED METEORITES. (3) CAIS RICH IN HIBONITE CONTAIN THE LARGEST ISOTOPIC ANOMALIES (IN CA AND TI) OF ANY SOLAR SYSTEM MATERIALS. WE WILL MEASURE THE ISOTOPIC COMPOSITIONS OF A NUMBER OF ELEMENTS IN WELL-CHARACTERIZED HIBONITE BY RIMS TO BETTER RESOLVE THE SOURCES OF THE ISOTOPIC COMPONENTS THAT FORMED OUR SOLAR SYSTEM. (4) THERE ARE SMALL VARIATIONS IN THE ISOTOPIC COMPOSITIONS OF A NUMBER OF ELEMENTS (CA TI CR ZR MO RU PD BA SM ND HF W OS) IN BULK SAMPLES OF DIFFERENT TYPES OF METEORITES; SOMEWHAT LARGER ISOTOPE ANOMALIES ARE REVEALED IN PROGRESSIVE CHEMICAL LEACHING EXPERIMENTS ON PRIMITIVE METEORITES. THE CARRIERS OF THESE ANOMALIES ARE UNKNOWN (EXCEPT FOR CR) BUT HOLD INFORMATION ABOUT SOURCES AND SOLAR NEBULAR MIXING. WE WILL MAP PRIMITIVE METEORITES AND IDPS AT FINE SPATIAL RESOLUTION TO SEARCH FOR THE CARRIERS OF ANOMALIES THAT HAVE BEEN REVEALED IN LEACHING EXPERIMENTS. (5) PRESOLAR GRAINS HAVE PROVEN TO BE A RICH SOURCE OF INFORMATION ABOUT INDIVIDUAL STARS. WE WILL STUDY THE ISOTOPIC COMPOSITIONS AND CHEMICAL ABUNDANCES OF MINOR AND TRACE ELEMENTS IN SIC GRAPHITE SILICATES AND OTHER PRESOLAR MATERIALS AS WELL AS SEARCH FOR INTERNAL HETEROGENEITIES WITHIN THESE GRAINS TO BETTER UNDERSTAND STELLAR NUCLEOSYNTHESIS IN AND CONDENSATION OF GRAINS AROUND ASYMPTOTIC GIANT BRANCH STARS AND SUPERNOVAE AND TO UNDERSTAND THE STARTING MATERIALS THAT COLLAPSED TO FORM THE SOLAR SYSTEM. (6) GEMS (GLASS WITH EMBEDDED METAL AND SULFIDES) ARE ENIGMATIC OBJECTS FOUND IN IDPS THAT MAY BE OF INTERSTELLAR ORIGIN. THEIR SMALL SIZE HAS PRECLUDED ISOTOPIC MEASUREMENTS; WE WILL ANALYZE THEM BY RIMS BEGINNING WITH FE AND MG AND PROCEEDING TO LOWER ABUNDANCE ELEMENTS. METHODOLOGY. CHILI THE CHICAGO INSTRUMENT FOR LASER IONIZATION IS A RIMS INSTRUMENT THAT IS DESIGNED FOR HIGH USEFUL YIELD AND NEARLY COMPLETE SUPPRESSION OF ISOBARIC INTERFERENCES FROM BOTH MONATOMIC AND MOLECULAR IONS. RIMS SCHEMES ARE AVAILABLE FOR ALL ELEMENTS LISTED ABOVE. ALSO AVAILABLE ARE SAMPLE CHARACTERIZATION AND PREPARATION EQUIPMENT: (1) A TESCAN LYRA3 FESEM-FIB EQUIPPED WITH EDS WDS AND EBSD; AND (2) A DUST-FREE CLEAN ROOM WITH MICROSCOPES AND A MICROMANIPULATOR. RELEVANCE. THE PROPOSED RESEARCH IS HIGHLY RELEVANT TO THE GOALS OF THE EMERGING WORLDS PROGRAM WHICH IS TARGETED AT IMPROVING UNDERSTANDING OF THE FORMATION AND EARLY EVOLUTION OF THE SOLAR SYSTEM AND WILL IMPACT MANY OF THE BULLETED ITEMS LISTED IN ROSES 2016 INCLUDING: PROTOPLANETARY DISK FORMATION AND EVOLUTION; LARGE-SCALE CHEMICAL AND ISOTOPIC FRACTIONATION PROCESSES; CHEMICAL AND PHYSICAL PROCESSING OF DUST; THE BULK PROPERTIES OF SOLAR SYSTEM BODIES; THE CHEMICAL AND PHYSICAL PROPERTIES OF ANCIENT MATERIALS; AND THE ORIGIN OF METEORITES AND METEORITE GROUPS.