The STEHLo project (Earth Sciences and evolution of our planet’s habitability: OTELo) is interested in the question of the ability of our planet to develop, welcome and maintain life on its surface over the long history. Planet Earth s was formed about 4.5 billion years ago and life most certainly appeared in the first 500 million years of its history. The conditions that have made it possible to make the Earth a planet are intimately linked to its intrinsic functioning, in particular to the exchanges between internal (mantle) and external (ocean, atmosphere, continents). To name a few, the volatile, light elements (C, H, O, N, S) are the elementary bricks of the living whose cycles must be understood because they are key to the history of the habitability of our planet. Oxygen, water and greenhouse gases (CO2, methane) are the pillars of controlling the development of life and the habitability of the Earth. It is certain that questions about the future evolution of the Earth and its environments, the habitability of other planets, and our ability to reliably model them, must be grounded in the lessons of the past. Such an approach represents the core of the STEHLo project, whose objectives concern the entire history of the Earth, for which isotopic analysis is a tool of choice that requires the processing of samples.