Influence of orbital perturbations on tethered space systems for active debris removal missions

Abstract

This paper analyses the influence of orbital perturbations on tethered space systems for active debris removal missions in low Earth orbit. Using a flexible (tethered) connection between the chaser satellite and a debris object it is possible to perform an active debris removal mission. For a successful mission, a stabilization and control of the tethered system is necessary. Since the debris object might be non-operational all maneuvers have to be performed by the chaser. Therefore, the development of control laws and equations of motion for the tethered system is indispensable. At the beginning of the development process for control laws it is required to determine the equation of motion of the system and therefore the applied forces. These can be distinguished in active (self-induced: e.g. thruster firing) and passive (foreign-induced: e.g. orbital perturbations) forces. With knowledge of the applied forces, the intensity and expected direction of the movement of the tethered system can be determined. This paper focuses on passive forces that originate from orbital perturbations in the low Earth orbit regime.For this a software tool called "Tether Orbital Perturbations Influence Determinator (TOPID)" is developed. The tool allows to determine the influence of selected orbit perturbations on the tethered space system. The influence is evaluated based on the change in length of the tether between the chaser and the target. In context of the first study five different targets have been selected depending on their criticality to the space debris environment. The influence of the orbital perturbations have been analyzed for the targets.

Dynamic Behavior Analysis and Stability Control of Tethered Satellite Formation Deployment

“…The aforementioned references indicate that little attention has been given to numerical studies on the accuracy of simplified TSS models, control stability and the influence of orbital eccentricity. However, tethers produce in-plane and out-of-plane swings and longitudinal and transverse vibrations as a result of complex perturbations [ 28 , 29 ], and a slight change in orbital eccentricity can significantly affect the original system. Previous studies show that analytical solutions for complex nonlinear models of TSS are difficult to obtain.…”