Electrodynamic Tether Deorbit of a Derelict Upper Stage: Lorentz-Force Sizing for a Five-Kilometre Bare Tether

This paper presents a computed design study of a civilian orbital-safety system based on Lorentz force on a current-carrying tether moving through the geomagnetic field. It is a computed study of a civilian orbital-safety system, with no targeting application and no weapon application. Status: SIMULATED, NOT MEASURED. Under the stated assumptions the sizing gives a orbital speed m per s of 7.51e+03, a motional emf V of 1.13e+03, and a mean current A of 0.63. Further computed quantities include lorentz force N of 0.0945; deceleration m per s2 of 7.88e-05; decay rate km per day of 12.8; approx days 700 to 250km of 35.1; tether mass kg of 42.4. The design is sized end to end from the stated assumptions in the deposited computation, so every headline number can be reproduced, challenged and revised. Where the approach performs poorly, that result is reported at the same size as the favourable results: the limitations section names the conditions under which this design should not be chosen. The contribution is a complete, auditable sizing for one operating principle, intended to be compared like-for-like with sizings built on other principles for the same task.