Earth observation satellites such as FACSAT, equipped with embedded hardware and software systems, require interaction with physical variables such as time, energy and space for their operation. In this paper, a FACSAT is characterized conceptually as a cyber-physical system. We propose a model that, based on a series of assumptions and restrictions, describes the operating principle of the system. Using this model, we describe the development of a tool for the automation of mission planning and scheduling that is modularly integrated into the mission control software, which is validated in real operational scenarios with the FACSAT-1 satellite.