On-orbit proximity operations require advanced guidance, navigation and control systems to obtain high pointing accuracy and very precise manoeuvring. The design of an attitude and orbit control is of primary importance in such delicate operations, since a spacecraft is subjected to many disturbance forces and torques, due to many sources, that lead to orbit variation (e.g. decay) and undesired angular accelerations. For missions with proximity operation, innovative Attitude Determination and Control Subsystem (ADCS) and a Guidance, Navigation and Control Subsystem (G, N &S) are of paramount importance. Orbit and attitude control is carried out thanks to the proper interactions of several elements, such as sensors, controller and actuators.