Contact Dynamics Modeling and Simulation of Tether Nets for Space-Debris Capture

A proposed method for containing the growth of space debris, which jeopardizes operation of spacecraft, is the active debris removal of massive derelict spacecraft and launcher upper stages by means of tether nets. The behavior of nets in space is not well known; therefore, numerical simulation is needed to gain understanding of deployment and capture dynamics. In this paper, a lumped-parameter approach for modeling the net and different models of contact dynamics are presented. A continuous compliant approach for the normal contact force and a modified damped bristle model for the friction force are chosen. The capability of the developed simulation tool to represent multiple dynamic conditions is demonstrated in this paper, and the results of a deployment dynamics simulation are presented; this reveals a snapping behavior of tension. Simulation of net-based capture of cylindrical debris in microgravity and vacuum conditions is performed with the presented tool. The effect of employing different contact force models on the overall results of capture is evaluated, both from a dynamical and a computational point of view, and reasons to prefer nonlinear models are discussed.