Application of Saturn’s Rings to Spacecraft Optical Navigation

Abstract

This work explores the feasibility of using images of Saturn’s ring system as a navigation resource for spacecraft. The perspective geometry of Saturn’s rings provides closed-form expressions for estimating a spacecraft’s relative position as well as its analytical covariance. Numerical simulations detail the performance and sensitivity of the position estimates. An extended Kalman filter fuses the relative position estimates with spacecraft dynamics for more accurate relative position and velocity estimates. An Enceladus sample collection mission serves as a case study where the proposed method seems viable. With filtering, simulation of an Enceladus sample-collection mission achieves maximum bounds of 7.19 km and for relative position and velocity estimates, respectively, during its Enceladus encounter. Autonomous navigation may reduce the cost of such a mission to the point where several small spacecraft can achieve the science objectives.