LONG-TERM SPACE MISSIONS WILL REQUIRE CLOSED-LOOP LIFE SUPPORT SYSTEMS THAT REGENERATE FOOD AND 0 2 FROM C02 AND H20. CHEMOHETEROTROPHIC ORGANISMS ARE ATTRACTIVE COMPONENTS OF SUCH A SYSTEM BECAUSE THEY CAN BE ENGINEERED TO PRODUCE A VARIETY OF ESSENTIAL NUTRIENTS. IN ORDER TO BE USED ON SPACE MISSIONS THERE MUST BE AN EFFICIENT PROCESS TO SUPPLY CHEMOHETEROTROPHS WITH THE CHEMICAL FEEDSTOCKS THEY NEED FOR GROWTH AND BIOSYNTHETIC OUTPUT. THE KEY CHEMICAL CHALLENGE IS TO USE POWER SOURCES AVAILABLE ON A SPACE MISSION TO CONVERT C02 AND H20 INTO 0 2 AND MULTI-CARBON (C2+) FEEDSTOCKS. THIS PROPOSAL WILL COMBINE ANALYSIS AND EXPERIMENTAL STUDIES TO ADVANCE NEW ROUTES FOR THE SYNTHESIS OF C2+ FEEDSTOCKS THAT ARE COMPATIBLE WITH THE CONSTRAINTS OF SPACE MISSIONS. THE ANALYSIS COMPONENT WILL QUANTITATIVELY COMPARE VARIOUS C2+ OXYGENATED COMPOUNDS FOR THEIR VALUE AS FEEDSTOCKS FOR CHEMOHETEROTROPHIC NUTRIENT PRODUCTION. IN PARALLEL WE WILL PERFORM EXPERIMENTS TO DEVELOP NOVEL ELECTROCHEMICAL AND THERMOCHEMICAL C2- OXYGENATE SYNTHESES. OUR ELECTROCHEMICAL STUDIES WILL FOCUS ON THE ELECTROREDUCTION OF CO WHICH CAN BE COUPLED TO AN UPSTREAM CORTO-CO CONVERSION PROCESS. WE WILL DEVELOP GAS DIFFUSION ELECTROLYSIS CELLS THAT OPTIMIZE THE MASS TRANSPORT OF CO TO ELECTROCATALYST PARTICLES AND EVALUATE THE PERFORMANCE OF NANOSTRUCTURED CU CATALYSTS IN THESE CELLS. THE THERMOCHEMICAL EXPERIMENTS WILL TARGET A NOVEL BASE-PROMOTED HYDROGENATION OF C02 INTO ACETATE AND OPTIMIZE A RECENTLY DISCOVERED REACTION THAT CONVERTS ACETATE AND FORMATE INTO SUCCINATE.