The paper centers on the problems of developing failure- and fault-tolerant systems for Earth remote sensing satellite constellation control. The study defines the concept of a complex that fail-safely performs a target task, in this case, the task of detecting a target event and monitoring its behavior and development, i.e. monitoring the target event, and gives a hierarchical satellite constellation structure. Findings of the research show that it is necessary to use dynamic redundancy, which can significantly increase the trajectory of self-controlled degradation and, accordingly, the satellite constellation active life. The complexity of the problem lies in ensuring the reliability of the results obtained when a large number of target events, both natural and man-caused, occur. The study introduces an approach to reduce hardware redundancy, i.e. monitor a larger number of events using a lower power satellite constellation, and proves that is possible to use the approach without losing the system reliability.