Orbital Estimation Using Two-Body Classical Orbital Elements as Measurement Updates

摘要

Currently, the Space Defense Center (SDC) uses the position and velocity data of a satellite track to update the orbital elements of the satellite. An alternate approach would be to process the radar data at the tracking site and transmit two-body orbital elements to SDC as measurement updates. This would significantly reduce the data load at SDC. The truth model used in this study to evaluate performance and provide measurement updates to the filters includes the first four zonal harmonics and the first sectoral harmonic of the geopotential and the air drag. The estimator models include two-body dynamics and J sub 2 perturbations. In addition, the derivative of the semi-major axis is used to estimate the effects due to air drag. Perfect dynamics with measurement noise are assumed for the filter models. Three filters are evaluated; Least Squares, Bayes, and Kalman. The performance of the three filters is similar. The Bayes and Kalman Filters are nearly the same and indistinguishable in this study. All three filters performed adequately with the following exceptions. The filters diverge when singularities are present in the classical orbital elements. All three filters underestimate the covariance of the estimates. Finally, the filters track noise in the estimate of the derivative of the semi-major axis, degrading the prediction capabilities of the filters. (Author)