• satellite coverage analysis
• satellite communication system design
• Inter-Satellite Link
• space engineering

This Master's Thesis study is developed in collaboration with the Domain Telecommunication Italy (DTI) of Thales Alenia Space Italia, located in Rome. The purpose of this study is to design an Inter-Satellite Link (ISL) in K/Ka-Band between a Geostationary Earth Orbit (GEO) satellite and a Low Earth Orbit (LEO) constellation of observation satellites.

In the first part a satellite coverage analysis is shown. The results of the current scenario are then compared with the results obtained using the Inter-Satellite Link. In terms of visibility, the worst cases of Inter-Satellite coverage are also analysed, as they are necessary for the design phase. In the second part, the results obtained from the telecommunication link budgets and from the considerations made on the compatibility subsystems are discussed. These results are used for the design of the final telecommunication system and allow to define the configurations of the Inter-Satellite communication subsystems. These links configurations are believed as high-potential application for business with institutional markets thanks to the possibility of making a system autonomous from Ground Segments. The guaranteed real-time connection with Grounds, allows a drastic reduction of visibility gaps which can be vital in some operational crisis scenarios.

This study has highlighted the remarkable advantages obtainable from an Inter-Satellite connection as a support for LEO observation constellations satellites. The exploitation of the GEO satellites as a "signal relay" has shown how the efficiency of these constellations can be increased by reducing the Response Time: the time frame between the submission of the request by the user and the delivery of the information to the user. In most cases the satellites of these constellations present a configuration of consolidated subsystems that can hardly be implemented by other devices. For this reason the study has tried to suggest a type of proposal that is as least invasive as possible in terms of power, accommodation and HW/SW complexity. This type of connection between satellites placed in different orbits may become a consolidated practice in the future.

For visibility analysis and also for scenarios simulations, it has been used the orbital simulator software STK developed by AGI (Analytical Graphics, Inc).