Minimum-variance estimation of reentry debris trajectories

A minimum-variance estimator is developed for reentry debris trajectories u sing discrete-time multiple sensor line-of-sight measurements. An integral state model is used for the unknown drag ballistic coefficient and lift bal listic coefficient. An extended Kalman filter is developed for the forward estimate and a Rauch-Tung-Striebel smoother is developed for the backward e stimate. The method is tested on nonlifting and lifting reentry trajectorie s that are synthesized using a high-fidelity trajectory simulator. The resu lts of this research show that reentry debris trajectories can be estimated using the approach developed despite the lack of accurate models for the a erodynamic coefficients.