Evaluation of Tethered Satellite System Models for Simulating Post-Capture Debris Towing

The increasing amount of space debris poses a significant threat to ongoing and future space missions in Earth’s orbit. Active Debris Removal is needed to prevent the growing amount of debris from becoming an overwhelming problem in the near future. This study explores the use of two lower-order tethered satellite system (TSS) models with four and eight sub-tethers to approximate high-fidelity net-based debris towing, thus reducing the computational costs of simulations. Net-based debris towings of two target debris – the Zenit-2 upper stage and the Apollo spacecraft – are considered for the model comparison. Particle Swarm Optimization is employed to identify the parameters of the tethered satellite system (TSS) models such that they match the system dynamics in the net-based simulations as closely as possible. After the TSS parameters are identified, the dynamics between the high-fidelity and lower-order models are compared using qualitative and quantitative methods, including visualization of the systems over time, root mean square errors between states, and comparison of the time evolution of states. The findings of this study demonstrate that the locations of the sub-tether attachments and the number of sub-tethers present in the lower-order models do not significantly affect their ability to match the dynamics of the net-based debris towing simulations. The TSS models also demonstrate better dynamics-matching ability with the Zenit-2 upper stage being present as the target, whereas the complex geometry of the Apollo spacecraft leads to greater dynamics deviations.