Precise numerical simulations of electrodynamic tethers for an active debris removal system

As a countermeasure for suppressing space debris growth, the Institute of Space Technology and Aeronautics, Japan Aerospace Exploration Agency (JAXA), is investigating an active space debris removal system that employs highly efficient electrodynamic tether (EDT) technology as its orbital transfer system. A small, expendable EDT package is under development that consists of a bare conductive tether and field emitter cathodes (FECs) that utilize carbon nanotubes. First, the status of the trial manufacture of the bare tether, reel mechanism, and the FECs are described. Some tests for example for measuring tensile strength and thermal expansion have been conducted on the tether. Next, precise numerical simulations are performed for some aspects of mission analysis, such as available electric currents, orbital changes, tether stability, and deployment dynamics. A tether is modeled as a lumped mass to take into account tether flexibility, and environment models (changes in the plasma density and geomagnetic field, and so on) are also considered. Measured parameters of the manufactured tether described above are reflected in the numerical simulations. Differences between the precise and simple models are compared and discussed.