COSMO-SkyMed Constellation Configurations: Current Status and Possible Evolutions

COSMO-SkyMed is an Earth Observation space programme funded by the Italian Ministry of Research and Italian Ministry of Defence (It-MoD) and conducted by the Italian Space Agency (ASI) in conjunction with It-MoD. In November 2010 the fourth and last COSMO-SkyMed satellite was successfully launched. It was integrated into the operational constellation after the positive conclusion of the commissioning phase in January 2011. The four satellites are placed in the same sun-synchronous dawn-dusk frozen orbit, designed in such a way to fulfil dual needs and to optimize the performances for a wide range of Civilian applications (e.g. risks management, agriculture/forestry, marine/coastal, geology) and Defence applications (surveillance, intelligence, crisis management, mission planning). The baseline four-satellite constellation configuration foresees that the satellites are placed on the same orbital plane with a difference of 90, 180, 270 and 360 deg in their respective anomalies. Currently the orbital configuration is composed of three satellites (namely PFM, FM#2 and FM#4) placed with a difference of 0, 180, and 270 deg in their respective anomalies, while a fourth satellite (namely FM#3) is placed in a tandem-like configuration with FM#2 (i.e. one-day temporal decorrelation). The aim of this paper is to analyze the orbital flexibility of COSMO-SkyMed constellation by performing a survey of the possible orbital interferometric configurations which could be achieved by the full COSMO-SkyMed constellation (e.g. tandem, tandem-like, double one-day tandem configuration, etc), focusing on their main features (e.g. temporal decorrelation, degradation of the temporal performances respect to the nominal equi-phased configuration, etc), highlighting the manoeuvres required for orbital configuration changes