Positioning of satellites through continuous firing

Orbital pushing is going to be an important task to plan, due to the increase of shared or piggyback launches that imply the release of small satellites in orbits different from the final one. Due to launch failures or to changes in the services to supply while operating, orbital reconfigurations could be considered an added value if they can be performed avoiding a considerable consumption of fuel that is not renewable. To this respect ion-engines could help because they are characterized by a high reliability and particular low fuel consumption. On the other hand the thrust is very low, so that long time operation is needed to accomplish the repositioning. First recovery by ion-engines was the unexpected repositioning of the satellite Artemis. Ion engines were installed just for experimentation, but they were used, in cooperation with other more traditional thrusters, to shift the satellite from his unwanted dangerous position (across Van Allen belts) to the operational location, avoiding the complete exploitation of all the available hydrazine. The paper explores the advantage to make use of a continuous firing technique by an ion-engine to change the orbital parameters