An Ion-Beam Shepherd for Contactless Removal of a Two-Tonne Derelict: Plume Momentum Budgets

This paper presents a computed design study of a civilian orbital-safety system based on contactless momentum transfer from an ion thruster plume impinging on the target. 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 effective force on target N of 0.0275, a target acceleration m per s2 of 1.38e-05, and a delta v 90d m per s of 107. Further computed quantities include delta v 180d m per s of 214; semi major axis change 180d km of 407; shepherd propellant 180d kg of 24.8; standoff m of 15. 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.