ESA GNC Conference Papers Repository

In the last decade the collaboration between European industries, research institutions and space agencies led to the development of concepts and technologies to enable Active Debris Removal missions. In particular, the ESA Clean Space initiative has been coordinating various studies involving manufacturers and system integrators to pursue the development of technologies for deorbiting systems, design for demise, and satellite passivation. Among others, e.Deorbit programme aims at launching in 2023 the first active debris removal mission. One of the concepts under study involves the rendezvous of a chaser with the large debris to be deorbited, the capture of the target using a space net or harpoon, and eventually the towing of the debris in the Earth atmosphere exploiting the propulsion system of the servicing satellite. Such solutions are also called pulling technologies because the last phase of the mission, i.e. the debris disposal, is carried out by means of a tethered tug manoeuvre. Much work has been done to date to develop and simulate the dynamics of tethered space tug manoeuvres, with major advances on the investigation of the stability conditions of dual-mass tethered systems. Despite the robust scientific background, only few experiments have been carried out on ground (e.g. SPHERES ground test facility) and in relevant environment (e.g. on parabolic flights and aboard the ISS), and none in full space environment. In this context, we propose a low-cost CubeSat mission that aims at demonstrating the feasibility of tethered space tug maneuvers and validating all key technologies, such as tether deployer, chaser ACDS subsystem, propulsion system for the re-entry manoeuvre. Moreover, the dynamics of both chaser and target will be closely monitored throughout the mission to assess the system dynamical stability. In this paper the concept will be described at a phase A level, reporting the primary objectives of the mission, a possible layout of the 3U CubeSat, the description of the in-orbit operations, preliminary design and calculation of all main subsystems (propulsive, tether, power, communications, ACDS). Furthermore, numerical simulations will be presented to investigate orbital decay, tether dynamics, chaser attitude dynamics, and attitude control of the chaser during the tug manoeuvre. The employed FORTRAN simulator was developed within a collaboration between University of Padova, MIT, and Airbus DS Huston and it has been used to define the test plan of the 'SPHERES Tether Demo' project.