Planning and scheduling algorithms for the COSMO-SkyMed constellation

The COSMO-SkyMed satellite constellation for the observation of the Earth is made of four satellites equipped with radar instruments and is intended for dual use, i.e. for security as well as for environmental monitoring purpose. The planning and scheduling problem for the COSMO-SkyMed constellation consists in selecting and synchronizing the operations needed to acquire the requested images of the Earth surface with the operations needed to transmit the image files to a set of ground stations. The planning and scheduling problem is solved every day on different time horizons and it must comply with a large number of technical and managerial constraints, such as set-up manoeuvres, use of shared resources on board, memory capacity, operational profiles, user quotas, split requests, deadlines and priorities. The objective is to maximize the number of images taken and transmitted. We developed a constructive algorithm with look-ahead and back-tracking capabilities, that produces feasible plans in a very short time, achieving the target of 1800 images per day.