In this paper, we identify several challenges and opportunities opened to agent and multiagent systems, in the domain of Earth observation constellations. While mono-satellite and small constellations have been largely studied, recent developments of next generation satellites open novel challenges and new tracks for research. We focus here on three important categories of challenges that manifest in this application field. The first one concerns the configuration of a constellation of satellites and the set of ground stations used to operate it, potentially owned by different actors. The question is about how to dimension and how to position the satellites over a set of orbits, and the related ground stations, to provide a better service and coordination. The second category regards offline planning and scheduling problems, which consists in finding solution methods to schedule observation and upload/download tasks over the constellation. Finally, the third category addresses the design of efficient and reactive online operation methods as to adapt and repair schedules in dynamics settings. Being naturally distributed and composed of multiple entities and users, these various problems clearly fit the multiagent paradigm, and may challenge researchers for many years.