Earth-Based Radiometric Tracking for Cislunar Spacecraft: Ranging, Doppler and Geometry Error Budgets

This paper presents a computed design study of a civilian orbital-safety system based on two-way radiometric ranging and Doppler from a three-station Earth network. 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 one way light time s of 1.28, a ranging sigma m of 1, and a doppler sigma mm per s of 0.05. Further computed quantities include plane of sky sigma km of 1.51; stations of 3; band GHz of 8.4; radial position sigma m of 1; velocity sigma mm per s of 0.05. 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.