EDT demonstration for keeping low altitude orbit using carbon nanotube tether

Abstract

This paper describes an electrodynamic tether system (EDT). Conductive tethers are used to overcome atmospheric resistance in low orbit and extend orbit life using EDT propulsion. First, based on the conceptual design, the feasibility of the EDT system has been evaluated through simulation. Especially, the induced electromotive force of the conductive tether has been clarified, the amount of current required to keep the orbital altitude, and the requirements for each device. Then, feasibilities of the key mission devices have been evaluated experimentally. Those are the conductive tether, the electron emission device, and the tether extension control mechanism. The conductive tether is planned to be made of carbon nanotubes, which are attracting attention as a new material, and its properties are evaluated. The electron-emitting device has been evaluated as a device that can be mounted on a micro/nano satellite. Tether extension mechanism was developed in our past project, then it should be evaluated with the purpose of adapting to conductive tether systems. Based on the evaluation, the orbital demonstration mission plan using a micro/nano satellite has been introduced. The mission is as follows. The conductive tether is extended and stabilized by the gravity gradient. By emitting electrons from an electron emitter mounted on a high-altitude satellite and collecting electrons on bare tether at low-altitude end, a current is generated from the high-altitude side to the low-altitude side. According to Fleming's law, the Lorentz force is generated in the direction of the orbiting accelerated, so it can be propelled in the upward direction of the orbit.