LABORATORY ANALYSIS OF CAPTURED SOLAR WIND (SW) RETURNED BY THE GENESIS DISCOVERY MISSION REVEALED THAT THE ISOTOPIC COMPOSITIONS OF OXYGEN AND NITROGEN IN THE SUN ARE DISTINCTLY DIFFERENT THAN THOSE IN ROCKY MATERIALS OF THE INNER SOLAR SYSTEM [1 2]. BECAUSE IT HAS THREE STABLE ISOTOPES THE OXYGEN DATA FURTHER SHOWED THAT THE DIFFERENCE BETWEEN THE SW AND PLANETARY COMPOSITIONS HAS BOTH MASS DEPENDENT AND NON-MASS DEPENDENT CHARACTERISTICS WITH THE LATTER BEING MORE SIGNIFICANT IN MAGNITUDE AND IN IMPORTANCE FOR UNDERSTANDING THE NATURE OF ISOTOPIC CHEMISTRY IN THE EARLY SOLAR SYSTEM AND/OR ITS PROGENITOR MOLECULAR CLOUD. THE DEGREE OF MASSDEPENDENT FRACTIONATION OF D17O AND D18O HYPOTHESIZED BY [1] IS QUALITATIVELY IN AGREEMENT WITH EXPECTATIONS BASED ON NOBLE GAS DATA AND ON MODELS OF SW ACCELERATION AND NOTABLY IS TOO SMALL TO SIGNIFICANTLY AFFECT THE D15N RESULTS [2]. NEVERTHELESS DEVELOPING A QUANTITATIVE UNDERSTANDING OF MASS-DEPENDENT FRACTIONATION EFFECTS IN THE ACCELERATION OF SOLAR WIND IS IMPORTANT FOR CONSTRAINING MODELS THAT MUST BE USED TO RELATE MEASURED SW ELEMENTAL ABUNDANCES TO PHOTOSPHERIC COMPOSITION AND FOR INTERPRETING OTHER LIGHT STABLE ISOTOPE MEASUREMENTS OF SW WHICH MIGHT SHOW SMALLER DEVIATIONS FROM TERRESTRIAL VALUES. OF PARTICULAR IMPORTANCE WOULD BE CARBON AND SULFUR NEITHER OF WHICH IS YET MEASURED IN GENESIS TARGETS. WE PROPOSE A THREE-YEAR PROJECT TO MEASURE THE ISOTOPIC COMPOSITIONS OF SELECT LIGHT ELEMENTS IN THE SOLAR WIND CAPTURED BY GENESIS AND BY REGOLITH PARTICLES FROM NEAR EARTH ASTEROID ITOKAWA WITH THE OVERARCHING GOAL OF DERIVING ACCURATE MASS-FRACTIONATION CORRECTED PHOTOSPHERIC ISOTOPIC ABUNDANCES OF B C N O AND S. THIS WILL BE ACCOMPLISHED BY NEW SECONDARY ION MASS SPECTROMETRY ANALYSES AND MODELING IN THREE RELATED TASKS: (1) MEASUREMENT OF 13C/12C AND 34S/32S IN SW FROM BULK AND CONCENTRATED GENESIS TARGETS (2) ANALYSES OF MG ISOTOPE COMPOSITIONS OF SW IN GENESIS SI BULK AND REGIME TARGETS TO DETERMINE MASS FRACTIONATION IN SW ACCELERATION IN COMPARISON WITH MODELS (3) DEPTH-PROFILING ANALYSES OF 11B/10B AND COORDINATED ANALYSES 13C/12C AND 15N/14N IN ITOKAWA REGOLITH GRAINS EXPOSED TO THE SW. TASKS 1 2 AND THE B DEPTH PROFILES IN TASK 3 WILL BE DONE AT UCLA WITH THE IMS-1290 ION MICROPROBE WHEREAS THE C AND N ISOTOPE PROFILES OF TASK 3 WILL BE MEASURED ON THE NANOSIMS AT COLLABORATOR DR. MOTOO ITO S LAB IN KOCHI INSTITUTE FOR CORE SAMPLE RESEARCH IN JAPAN. THE RESULTS FROM TASK 1 CORRECTED FOR MASS-DEPENDENT FRACTIONATION VIA TASK 2 WILL BE EVALUATED ALONG WITH METEORITIC AND PHOTOSPHERIC INFRARED SPECTRAL DATA [3] IN THE CONTEXT OF PHOTOCHEMICAL FRACTIONATION MODELS. SAMPLES REQUIRED FOR THIS WORK WILL BE REQUESTED BOTH FROM NASA/CAPTEM AND JAXA. THE PROPOSED WORK IS DIRECTLY RELEVANT TO THE GOALS OF THE LARS PROGRAM AS IT IS FOCUSED ON THE ANALYSIS OF ASTROMATERIALS RETURNED BY PLANETARY MISSIONS. ADDITIONALLY ANALYTICAL METHODS DEVELOPED IN THIS STUDY WILL BE DIRECTLY APPLICABLE TO SAMPLES RETURNED FROM EXTANT MISSIONS OSIRIS-REX AND HAYABUSA-2. REFERENCES: [1] MCKEEGAN ET AL. (2011) SCIENCE 332 1528. [2] MARTY ET AL. (2011) SCIENCE 332 1533. [3] LYONS ET AL. (2018) NATURE COMM. 9 908.