ET-Class: An Energy Transfer-Based Classification of Space Debris Removal Methods and Missions

Abstract

Space debris is positioned as a fatal problem for current and future space missions. Many effective space debris removal methods have been proposed in the past decade, and several techniques have been either tested on the ground or in parabolic flight experiments. Nevertheless, no uncooperative debris has been removed from any orbit until this moment. Therefore, to expand this research field and progressing the development of space debris removal technologies, this paper reviews and compares the existing technologies with past, present, and future methods and missions. Moreover, since one of the critical problems when designing space debris removal solutions is how to transfer the energy between the chaser/de-orbiting kit and target during the first interaction, this paper proposes a novel classification approach, named ET-Class (Energy Transfer Class). This classification approach provides an energy-based perspective to the space debris phenomenon by classifying how existing methods dissipate or store energy during the first contact.

Hybrid-Compliant System for Soft Capture of Uncooperative Space Debris

“…The hybrid compliance's length l m is equal to 0.05m since it is the sum of two lengths: l m = l s + l a ; the length l s of the passive physical compliance, equal to 0.025 m, and the maximum displacement l a of the linear actuators' moving parts, equal to 0.025 m. The schematic of the system under simulation study as designed in Simscape is shown in Figure 15. The algorithm runs for the range of stiffness values k m between [0.1-0.5] N/m, with a step of 0.1 N/m, for a range of space debris mass m d between [1-100] kg, with a step of 1 kg, and for a range of minimum contact time t c required for completion of the capturing between [4][5][6][7][8][9][10][11][12] s, with steps of 2 s.…”

“…The resulting diagram is shown in Figure 16, providing the relation between these variables. More detailed visualization of the data of Figure 16 is provided for each contact time in the range of [4][5][6][7][8][9][10][11][12] s in Appendix A. The lines depicted in the 3D diagram correspond to points in 3D space, representing the successful cases obtained from the algorithm.…”

“…Each point along the line represents three distinct values, namely: space debris mass, minimum contact time achieved, and hybrid compliance stiffness coefficient. Note that the [4][5][6][7][8][9][10][11][12] s range for this simulation for the minimum contact time required was selected since it was sufficient to showcase the necessity of tuning the system's compliance and, therefore, of the hybrid compliance concept. Simulation results for minimum contact time required greater than 12 s show that hybrid compliance is even more necessary if we want to target a wide range of debris between 0-100 kg.…”

“…Capturing mechanisms can interact differently with the debris; an Energy-Transfer Classification (ET-Class) was proposed in [9]. For instance, the Impact Energy Dissipation (ET2) class implies a capture with a decrease of energy at the first impact.…”

“…The proposed flexible, versatile hybrid-compliant system of class ET2 [9], custombuilt to fit a CubeSat, is displayed in Figure 1. This new system targets a vast range of small debris, enabling a profitable one-to-many solution.…”