Autonomous orbit determination for satelite formations using relative sensing: observability analysis and optimization

TL;DR

This paper explores autonomous orbit determination for satellite formations using relative sensing, analyzing observability, optimizing spacecraft placement, and examining measurement configurations to improve accuracy and system robustness.

Contribution

It introduces an observability analysis and optimization framework for relative sensing-based orbit determination in satellite formations, with application to the SunRISE mission.

Findings

The system is observable but ill-conditioned.

Optimal spacecraft placement enhances positioning accuracy.

Partial measurement removal can maintain observability.

Abstract

Orbit determination of spacecraft in orbit has been mostly dependent on either GNSS satellite signals or ground station telemetry. Both methods present their limitations, however: GNSS signals can only be used effectively in earth orbit, and ground-based orbit determination presents an inherent latency that increases with the Earth-spacecraft distance. For spacecraft flying formations, an alternative method of orbit determination, independent of external signals, consists in the observation of the spacecraft's position with respect to the central body through the relative positioning history of the spacecraft within the formation. In this paper, the potential of the relative positioning method is demonstrated in the context of the SunRISE mission, and compared with the mission's previously proposed orbit determination methods. An optimization study is then made to find the optimal placement of a new spacecraft in the formation so as to maximize the positioning accuracy of the system. Finally, the possibility of removing part of the system's relative bearing measurements while maintaing its observability is also studied. The resulting system is found to be observable, but ill-conditioned.