AS A SPECIALIST IN ISOTOPE GEOCHEMISTRY AND GEOCHRONOLOGY I ADDRESS SCIENTIFIC QUESTIONS ON PLANETARY SURFACE PROCESSES USING GEOCHEMICAL ANALYSES ON ROCK MINERAL AND GLASS SAMPLES FROM EARTH APOLLO LUNAR SAMPLES AND MARTIAN METEORITES IN MY MASS SPECTROMETRY LABORATORIES AT BERKELEY. IN THIS PROPOSAL I ADDRESS IMPORTANT CONSIDERATIONS FOR MARS 2020 SAMPLE COLLECTION TO ENSURE THE SUCCESS OF FUTURE LABORATORY ANALYSES TO ADDRESS PROBLEMS ASSOCIATED WITH THE FOLLOWING SCIENCE QUESTIONS: (I) QUANTIFYING TIMING OF SPECIFIC IMPACT FEATURES AND SURFACES ON MARS USING RADIOISOTOPE GEOCHRONOLOGY (WITH A FOCUS ON 40AR/39AR U-PB AND (U-TH)/HE SYSTEMATICS) ON BRECCIAS IMPACT GLASS AND MINERALS (II) QUANTIFYING SURFACE EXPOSURE AGES AND COSMOGENIC NUCLIDES PRODUCTION RATES (III) PLACING QUANTITATIVE CONSTRAINTS ON THE COSMIC RAY FLUENCE AND ASSOCIATED RADIATION DAMAGE EXPERIENCED BY NEAR-SURFACE SAMPLES (IV) QUANTIFYING SEDIMENT PROVENANCE GEOCHRONOLOGY AND EXHUMATION/EROSION RATES USING THERMOCHRONOLOGY (V) QUANTIFYING NEAR-SURFACE TEMPERATURE HISTORIES USING OPEN SYSTEM BEHAVIOR OF NOBLE GAS NUCLIDES (BOTH RADIOGENIC AND COSMOGENIC) (VI) CONSTRAINING PAST ATMOSPHERIC COMPOSITIONS FROM GASSES TRAPPED IN SOLIDS.