Geosynchronous satellite maneuver detection and orbit recovery using ground based optical tracking

Abstract

Geosynchronous satellite orbit maintenance is a very important issue. Satellites maneuver frequently requiring the ability to detect unknown maneuvers for target satellites and quickly recover an accurate orbit. This study uses angles only ground based optical tracking to detect maneuvers and recover orbits for geosynchronous satellites. Using the Analytical Graphics Inc. Orbit Determination Tool Kit sequential estimation software, a sequential estimation filter was "tuned" and validated in various ways. Then, a parametric study of maneuver size and time required to detect a maneuver was done via simulation. Simulated maneuvers ranging from Av's of 0.01 m/s to 1.0 m/s are discussed. Also examined are multiple methods to recover the orbit after such maneuvers are detected. Orbits are recovered for simulated maneuvers and for a real data case of unknown maneuver size. This work is important towards developing more automatic methods of detecting maneuvers for a large population of active geosynchronous satellites. Specific contributions made by this thesis include the following:

(cont.) the process and results of "tuning" of the sequential filter for a geosynchronous satellite using high accuracy ground based optical tracking data, the methods of orbit and covariance validation including an orbit overlap analysis and a statistical method using measurements, a parametric study for maneuver detection, and exploring methods for recovering post maneuver orbits quickly and accurately. With the tuned filter and optical tracking, simulations showed that a Av of 1.0 m/s could be detected as soon as 15 minutes after the maneuver, a Av of 0.1 m/s could be discernible within 6 hours and easily detected by 12 hours, and a Av of 0.01 m/s took from 12 to 24 hours to detect with confidence. The best demonstrated means for post-maneuver orbit recovery utilized a method of estimating the approximate maneuver time using the pre-maneuver filter orbit and an approximate post maneuver orbit followed by the "sprinkling" of a number of maneuvers over that period with Av's of 0 m/s but with finite covariances, and then filtering through that period.