Terrestrial scale model testing of a motorised propulsion tether

This paper comprises an account of research carried out in partial fulfilment of an agreed contract between the authors and the European Space Agency's European Space Research and Technology Centre (ESTEC). The principal remit of this contract has been to explore how to design a scale model which is as representative as possible of the dynamics of a full-size motorised symmetrical tether system, and then to build and test the scale model. The scale model system is intended to be representative of the full size concepts that have been previously discussed by the same authors. However, the experiment is to run on Earth, on a large ice bed, and will constrain the system to twodimensional spin-up motion, whilst minimising friction as far as possible. This research is relevant and timely because of the current lack of hard information relating to the spin-up performance of rotating tethers deployed in space and the fact that scaling extrapolations may allow some useful conclusions relevant to the space environment to be drawn from these terrestrial tests. To this end certain key questions relating to the practical feasibility of motorised spinning tether propulsion systems are to be answered during the experimental test phase, however it is the dynamical scaling analyses and the conceptual design of the experiment that are reported upon in this paper.