Recent observations combined with theoretical simulations of coronal environments of young solar analogs suggest that the early Earth have been exposed to high level of ionizing radiation and frequent solar energetic particle events from the young Sun. What is the impact of this high-energy radiation on atmospheric chemistry of the early terrestrial type planets? In this review, I present recent results from the photochemical and collisional chemistry atmospheric model of the weakly reducing atmosphere of early Earth. We show that as energetic protons can reach the lower atmospheres of the early Earth and Mars, induce ionization, and thus produce cascades of impact electrons that are instrumental in exciting, ionizing and dissociating molecular nitrogen, carbon dioxide, methane and water vapor. This results in the formation of abundant nitrous oxide, hydrogen cyanide and more complex molecules in the gas phase. This model suggests that two fundamental paradoxes for the early Earth environments, the origin of prebiotic chemistry on early Earth and the Faint Young Sun (FYS) paradox can be addressed within a unified chemical network driven by the persistent energy sources from the young Sun. While nitrous oxide is a potent greenhouse gas, which is capable of warming the early Earth atmosphere, the formation of abundant hydrogen cyanide and associated building blocks of life. Application of the three-dimensional Global Climate Model, ROCKE3D, have provided the solution for the FYS paradox that can explain the existence of the standing bodies of liquid water on early Earth’s surface, water is a crucial ingredient of forming formamide that promotes further polymerization of building blocks of life on the planetary surfaces. Our recent laboratory experiments performed at Yokohama National University using the proton accelerator at Tokyo Institute of Technology suggest that SEP driven protons can efficiently moderate the production of amino acids and other complex molecules in a weakly reducing atmospheric environment. The proton ignited production rates of amino acids are by 5 orders of magnitude greater as compared to lightning and UV energy sources. We combine these theoretical and experimental results to conclude that the high energy ionizing radiation from the young Sun and active stars has a high potential to promote the formation of the major ingredients of biogenic habitability on the early Earth, Mars and Earth-like exoplanets.

Fundamental chemical paradoxes for the early Earth under the young active sun

Macromolecular Chemistry: The Second Century

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ACS Spring 2020 National Meeting & Expo

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.