Habitability of Exo-Earths in various atmospheric oxidative conditions

ongoing

Among the thousands of extrasolar planets discovered, Earth-like objects focus our attention to seek new habitable worlds. Eleven Earth-sized planets have already been discovered in the Habitable Zone (HZ) of their host-star, including three in the TRAPPIST-1 planetary system. Deciphering their atmospheres is the challenge of the next decade in exoplanetary science, stressing out urgent needs in fundamental data for these objects. My aim is to investigate how the atmospheric organic reservoir forms and evolves in the frame of humid exoplanetary atmospheres in Habitable Zone. I will also quantify the impact of theses processes on the climate and on the potential for prebiotic chemistry on these planets. I propose to consider the role of organic aerosols as prebio-signature: those are nanoparticles chemically produced in the atmosphere. I will address the capacity of exo-Earths atmospheres to produce organic aerosols in various oxidative conditions, and their further physical and chemical interactions with atmospheric water. To tackle these questions, I will combine experiments and models to discover the reactivity that occurs in atmospheres within an extensive range of oxidation conditions. I will experimentally determine the physical properties of the aerosols, and then model their radiative impact and their propensity to generate clouds in the atmosphere. I will also experimentally identify the prebiotic molecules composing the aerosols that dissolve into clouds. This transfer from the dry organic reservoir towards liquid water is indeed critical for the emergence of life. The ERC-AdG Oxyplanets project will contribute to interpret and suggest observations for the future NASA-JWST and ESA-ARIEL space missions. Furthermore, it will reinforce our knowledge of the habitability of Earth-like exo-worlds, potentially reappraising the conditions for life to appear on the early-Earth.