Design and testing of a space mechanism for tether deployment

A mechanism for control of space tether deployment is presented and discussed in this paper. This friction device, called the "barberpole," was derived from the textile industry. The mechanism was analyzed, developed, and tested for the second Young Engineers' Satellite mission (YES2), which is intended to feature the first European tether deployment. YES2 further aims to use the tether to accurately deorbit a small innovative reentry capsule. The barberpole is used for precisely guiding the dynamics of a capsule by controlling the deployment velocity of a tether that connects the capsule to an orbiting platform, in this case the Foton satellite. Design steps, derivation of a mathematical model, thermal analysis, and experimental results of the device are presented in this paper. The exponential dependency of applied friction force vs number of tether wraps around the pole is theoretically and experimentally proved. Friction performance and predictability are discussed based on experiments performed both on ground using a custom-built test rig and during parabolic flight campaigns. The work highlights the suitability of the barberpole design for space tether applications.