The Origin of the Terrestrial Atmosphere: Early Fractionation and Cometary Accretion

Despite decades of efforts aimed at unraveling its origin, the terrestrial atmosphere is still considered to be one of the most puzzling enigmas in earth sciences. Remote observations will provide information on the atmospheres of extra-solar planets, some of these may prove to be hospitable for life. Understanding the origin of Earth’s atmosphere thus improves our knowledge of the sources and processes that permitted the emergence of life within the solar system and beyond. Noble gases are sensitive tracers for investigating this question. Indeed, they span a large range of atomic masses, have many isotopes, and are chemically inert.