The holistic understanding of the Earth’s water and energy cycle remains one of the grand challenges that the international scientific community needs to address in the next decade. The Raincast project is a multi-platform and multi-sensor study to address the requirement from the research and operational communities for global precipitation measurements. Raincast aims at identifying and consolidating the science requirements for a satellite mission that could complement the existing space-based precipitation observing system and that could optimally liaise with efforts currently made by other agencies in this area (especially by NASA and JAXA). Because of the complexity of the cloud and precipitation processes the study capitalizes on the most recent advancement and mission concepts for precipitation observations with state-of-the-art instrumentation (including multi-frequency radars, radar-radiometer synergies, constellations of cubesat radars) and makes full use of the most recent advancements in inversion methods for the estimation of precipitation variables from primary measurements (e.g. latest ice scattering libraries, physical relationships derived by in-situ measurements).