Atmospheric tracing of Earth's evolution

ongoing

Planetary atmospheres are fundamental reservoirs controlling the habitability of planets. The chemical and isotopic compositions of atmospheric constituents also hold clues on the geological evolution of the entire planetary body. Today, Earth's atmosphere contains about 80% dinitrogen and 20% dioxygen. Yet, there is no scientific consensus on how and why these two molecules emerged and persisted in the Earth's atmosphere. The interactions between the atmosphere and the continental crust also play a major role in controlling the bio-availability of nutrients and the composition of the atmosphere, and thus the climate. However, the evolution of the volume of continental crust over time is strongly debated. Project ATTRACTE will significantly improve our knowledge of the main drivers of atmospheric evolution over time. This will be achieved by going back in time and following the evolution of the composition of the Earth's atmosphere over geological eons. Analyses of gases contained in traditional and new paleo-atmospheric proxies, the post-impact hydrothermal minerals, will be carried out with innovative mass spectrometry techniques. The isotopic composition of paleo-atmospheric xenon will provide new constraints on the history of hydrogen escape for the Archean Earth. Coupled argon and nitrogen measurements will allow to determine, for the first time, the evolution of the partial pressure of atmospheric dinitrogen. Paleo-atmospheric data gathered during the project will be fed in numerical models of Earth's atmospheric and crustal evolution. This will allow to reconstruct how volatile elements have been exchanged between the silicate Earth and the atmosphere through time. Results gathered during project ATTRACTE will ultimately provide new datasets for climate studies of the ancient Earth but will also help building the scientific framework required to interpret future observations of exoplanetary atmospheres and to portray the geology of extrasolar planets.