Short Electrodynamic Tethers

ESA's General Study Programme; Ref. Contract 13395/98/NL/MV with Univerisdad Politecnica de Madrid (S) and Universida de Sevilla (S) 1999



Electrodynamic (ED) bare tethers are the best systems to deorbit S/C at the end of their service. For near polar orbits, usual tethers are kept vertical by the gravity gradient, yield too weak magnetic drag. Here we propose keeping tethers perpendicular to the orbital plane. They must be rigid and short for structural reasons, requiring power supply like ion thrusters. Tethers tube-booms that can be rolled up on a drum would lie on each side of the S/C. One boom, carrying an idle Hollow Cathode, collect electrons; the opposite booms HC ejects electrons. Special HC arrangements to avoid net magnetic torque are discussed. Power source switching must revert the current twice per orbit. Tether orientation is kept Thomson stable by having the system spin around the tether axis. Also briefly discussed is a second scheme having 4 booms at 90 degrees from each other and rotating fast in an inertial plane perpendicular to Earth's polar axis. Download the postscript file of the Statement of Work



Paper published in Proceedings of 7th Spacecraft Charging Technology Conference



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