COSMO-SkyMed full constellation orbital flexibility and interferometric capabilities

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 and integrated into the 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), providing a preliminary quantitative assessment of the interferometric products quality performance.