The Mechanics of Motorised Momentum Exchange Tethers with Application to Active Debris Removal from Low Earth Orbit Seminar

This presentation will address some of the theoretical and practical challenges inherent in applying momentum exchange space tethers to active debris removal in low Earth orbit (LEO). We will start by placing current momentum exchange tether mechanics in a historical context, particularly since 1966, and will lead on to define two candidate coordinate systems for the representation of the three dimensional dynamics of a stiffened ‘dumbbell’ tether on circular and elliptical orbits, and a set of nonlinear ordinary differential equations will be summarised for the dynamics of a dumbbell tether on an inclined elliptical orbit. This will provide the necessary orbital setting then to consider the tradeoffs that emerge when trying to maximise strength and performance against the practical constraints of cost and longevity in the arduous environment of LEO. A mission architecture will be summarised for continuous two-way payload exchange propelled by motorised momentum exchange tethers (MMETs) in LEO and a motorised lunavator tether operating in low Lunar orbit (LLO). From this point the presentation will diverge to consider the localised problem of active debris removal (ADR) in LEO using MMETs, and the challenges of ADR in this location will be considered. A simple planar reference model will be presented, in the context of the high level of mass asymmetry which would come about when large pieces of debris are retrieved by the tether system, and estimates of performance will be presented. Finally, a scaling study will be discussed by which a small terrestrial model might be designed for use as a basis for an experimental test campaign to check aspects of MMET deployment performance and debris capture. The seminar will end with some suggestions for future work.