Autonomous onboard estimation of mean orbital elements for geostationary electric-propulsion satellites

Mean orbital elements estimation for geostationary (GEO) satellites is important for related studies, including station-keeping, rendezvous and end-of-life disposal. With increasingly limited operational slots in GEO region and the advance of all-electric-propulsion satellites, a fast and accurate mean orbital element estimation tool is necessary. In order to balance estimation precision and mission cost as well as to be independent of the ground station, this paper develops an autonomous onboard estimation method of the mean orbital elements for geostationary electric-propulsion satellites. Natural perturbations in GEO, including Earth's triaxiality, luni-solar attractions, and solar radiation pressure, are considered. Terms of appropriate orders due to these effects are chosen to model the semi-analytical dynamics, where modified short-period variations and differential mean orbital elements are derived. Regarding mean orbital elements as state variables and osculating orbital elements as measurements, a filter as well as analytical Jacobians is formulated to make the accurate estimation. Five scenarios are simulated to validate the accuracy and efficiency of the proposed method in the GEO region.