Low-thrust strategies and implications in the perspective of space debris mitigation for large constellations

The planned future generation of large constellations of satellites in orbit around the Earth considers the application of low-thrust devices for the various phases of the mission. This choice is mainly due to the advantage of reducing the launch mass, possibly increasing the payload mass, while keeping advanced maneuvering capabilities. The aim of this work is to address the operational aspects and the implications related to the collision avoidance during the whole lifecycle of a satellite. We focus on the existing proposals for large constellations, taking as study cases the OneWeb constellation located at 1200 km of altitude and the Starlink constellation located at 550 km of altitude. We develop a software suite to generate realistic conjunction events between a satellite of the given constellation and the space debris environment, considering the orbit raising, the operational phase and the decommissioning phase of the mission. In case of a collision risk above a well-defined threshold, we fit the best parameters (orientation, and thrust duration) defining a collision avoidance with a low-thrust. The final goal is to provide the main features expected for the collision avoidance maneuvers of the proposed future missions.