Redox Disequilibrium in the Clouds of Venus: A Sign of Life?

Simultaneous occurrence of certain reduced (hydrides such as CH4) and oxidized (oxides or just O2) molecules have been proposed to serve as spectral signatures for life. Some of these Redox Disequilibrium Pairs (RDPs) have claimed detections on Mars and Venus. On Venus, particularly NH3, PH3 and O2 based on probe and ground-based data. Our project proposes new laboratory experiments to test abiotic production mechanisms for these PDPs, in particular novel photochemical reactions over acidic surfaces on aerosol particles. We will then put the yields of these mechanisms into the context of the Venusian atmosphere via chemical models. In addition, we will perform evolutionary models for Venus to study whether Venus might have had an ocean in its history, providing habitable conditions in its past, and how the water disappeared via atmospheric escape. The upcoming DaVinci, EnVision and the Life Finder Venus exploration missions will provide excellent and timely opportunities to check and verify our conclusions.