From a seething ball of magma ocean surrounded by a thick atmosphere made of silicate vapor, over half a billion years, known as the Hadean era, the Earth evolved into a tamed planet where carbon-based macromolecules became stable and eventually thrived.

During the Hadean eon, the atmosphere experienced its most dramatic transformations. An abundance of greenhouse gases prevented runaway cooling in the face of a dimmer Sun; however, the concentrations, chemistry, and decline rates of these gases are still unknown. Reconstructing this intriguing metamorphosis is hindered by the scarcity of Hadean samples, a vast parameter space, and the volatile flux estimates that mainly depend on empirical extrapolations. The formation of the first crust and the condensation of the hydrosphere add further complications, and few constraints exist for all these processes.

Here, we share the story of our long-term effort to understand the evolution of our planet during the Hadean, with a special focus on the Hadean atmosphere (via the new ERC project DAWN).

We use multi-scale numerical approaches, starting at the atomic level and ending at the planetary scale, to simulate the behavior and evolution of the atmosphere during the Hadean, retrace the major volatile fluxes between geological reservoirs and their contributions to the atmosphere, and dynamically integrate gas losses to space, incoming meteoritic contributions, and fast-changing surface conditions, including the appearance of the hydrosphere. We explore the chemical and catalytic pathways that occurred on the warm early surface, enabling the stabilization of primitive prebiotic organic molecules, the formation of a breathable atmosphere, and the development of a habitable planet.