This NEOMI project is a very first step towards the potential launch of a new satellite in the future. Within the project, the potential of a new active microwave mission will be explored. It will aim to address some of the existing uncertainties in terrestrial water and carbon cycles, and allow us to improve our understanding of land–atmosphere interactions. The project (and potential mission) is entitled Sub-daily Land Atmosphere INTEractions (SLAINTE). Once launched, SLAINTE will provide sub-daily microwave data to monitor rapid variations in water stores within the soil–vegetation continuum. It will be valuable for carbon and evaporation research, agricultural practices (irrigation), forestry, natural hazards and weather forecasting, among other sectors.