The mechanics of motorised momentum exchange tethers when applied to active debris removal from LEO

Abstract

Abstract. The concept of momentum exchange when applied to space tethers for propulsion is well established, and a considerable body of literature now exists on the on-orbit modelling, the dynamics, and also the control of a large range of tether system applications. The authors consider here a new application for the Motorised Momentum Exchange Tether by highlighting three key stages of development leading to a conceptualisation that can subsequently be developed into a technology for Active Debris Removal. The paper starts with a study of the on-orbit mechanics of a full sized motorised tether in which it is shown that a laden and therefore highly massasymmetrical tether can still be forced to spin, and certainly to librate, thereby confirming its possible usefulness for active debris removal (ADR). The second part of the paper concentrates on the modelling of the centripetal deployment of a symmetrical MMET in order to get it initialized for debris removal operations, and the third and final part of the paper provides an entry into scale modelling for low cost mission design and testing. It is shown that the motorised momentum exchange tether offers a potential solution to the removal of large pieces of orbital debris, and that dynamic methodologies can be implemented to in order to optimise the emergent design.

Validation of enabling technologies for deorbiting devices based on electrodynamic tethers

“…The deployment dynamics of a tethered system is highly nonlinear [60][61] [62] and the Coriolis accelerations acting on the tip masses leads to a configuration of the tethered system with libration amplitudes that are typically in the range 40°-50° if uncontrolled [63]. Consequently, the first step in the design of a deployment trajectory is to compute tether length and velocity time profiles that bring the system from given initial conditions to a small libration amplitude at the end of the deployment maneuver.…”