Investigation of on-orbit electrodynamic tether deployment by ground experiment and numerical simulation using a detailed friction model

The Japan Aerospace Exploration Agency (J AX A) has been investigating electrodynamic tether (EDT) systems as an effective means to reduce the growth of space debris. An EDT system attached to a space debris object can provide it with thrust without requiring propellant, and so can be used to de-orbit debris efficiently. In some previous flight experiments, tether deployment stopped halfway because the deployment friction was greater than expected. In our previous studies we modeled the friction force as a function of deployment velocity, but the result showed wide variability, and more accurate estimates were required. This study therefore further investigates deployment friction by laboratory tests and deployment dynamics by numerical simulations. First, we estimated deployment friction by deployment experiments using a high sensitivity force sensor. These experiments not only gave a deployment friction model as a detailed linear function of deployment velocity, but also revealed two qualitative characteristics of deployment: a vibration tendency and deployment being stopped by the tether becoming trapped within the spool or caught between the spool and a reel case. Next, on-orbit tether deployment using an EDT mechanism proposed for a future flight demonstration was analyzed by numerical simulation. This simulation showed that the frictional vibration tendency and stoppages due snagging of the tether observed in the ground experiment had little effect on the success of tether deployment on orbit.