Persistent Responsive Real-Time Earth Observation small satellite constellation mission (PERTEO) is a study dedicated to provide a global democratic service to support disaster management. Earth observation and satellite-based communications play a key role to support disaster management targeting responsiveness and the persistence of the service. In the terminology of on-demand Copernicus services, responsiveness is determined by the lead-time and latency. The persistence is determined by the availability and by the revisit time of the service. Current satellite-based disaster management services are neither persistent nor are they highly responsive. In the proposed mission, a responsive real-time service would be provided, through the combination of edge-computing for on-demand applications (ML/AI) and global persistent communications. Persistency would be provided through a heterogeneous constellation of small satellites, including optical and SAR payloads. A persistent comms link, e.g. GEO-relay or ISL, enables software defined real-time changes in the satellite tasking, in the satellite application configuration (i.e. AI app change), and enables real-time global product delivery. To provide a democratic global service, this will also include direct-to-ground delivery. This idea and mission would dramatically improve satellite-based disaster management services, allowing nations to prepare and respond to future crises more effectively.