A SPACE TUG FOR SATELLITES SERVICING

The paper deals with the analysis of a space tug to be used in support of Earth satellites transfer manoeuvres. Usually Earth satellites are released in a non-definitive low orbit, depending on the adopted launcher, and they need to be equipped with an adequate propulsion system able to perform the transfer to their final operational location. In order to reduce the mass at launch of the satellite system, an element pre-deployed on orbit, i.e. the space tug, can be exploited to perform the transfer manoeuvres; this allows simplifying the propulsion requirements for the satellites, with a consequent decrease of mass and volume, in favour of larger payloads. Several utilization scenarios can be identified, which may correspond to different requirements for the definition of the tug. In any case the idea is to have a system able to perform many satellites transfers from low to high orbit and exploit as much as possible the Italian assets (e.g. VEGA launcher). The paper reports a detailed description of the utilization scenario, defining the missions and the major elements. In particular the adopted methodology and the main results are discussed, highlighting the analyses and trade-offs carried out in order to define the most convenient mission strategy.