Design challenges and safety concept for the AVANTI experiment

AVANTI is a formation-flight experiment involving two noncooperative satellites. After a brief overview of the challenges that experiment design and scenario induce, this paper presents the safety concept retained to guarantee the safety of the formation. The peculiarity of the proposed approach is that it does not rely on the continuous availability of tracking data of the client spacecraft but rather exploits the concept of passive safety of special relative trajectories. To this end, the formation safety criterion based on the minimum distance normal to the flight direction has been extended in order to be applicable also to drifting relative orbits, resulting from non-vanishing relative semi-major axis encountered during a rendezvous or produced by the action of the differential aerodynamic drag.