Sequential Estimation of Apogee Boost Maneuver Parameters.

Kurzfassung

Within the positioning phase of geostationary satellites the performance of the Apogee Motor Firings is crucial to the success of the mission. Hence, the capability to monitor and estimate extended maneuvers is of high interest for spacecraft operations. In this paper the features of the completely revised and consid- erably extended ODEM (Orbit Determination System including Ex- tended Maneuvers) orbit determination software, that comprise the replacement of a Kalman Filter by a least-squares estimation algorithm and the extension to modeling and estimation of several instantaneous impulsive maneuvers in addition to the extended maneuver, are applied to the analysis of Apogee Motor Firings. Based on the experience with the previous ODEM version, the impact of Kalman Filter and least-squares estimation methods on the ana- lysis of Apogee Boost Motor (ABM) phases is investigated. To this end, tracking data from the recently performed positioning of the EUTELSAT Hot Bird 1 telecommunication satellite are utilized to compare the reliability, stability, and performance of both esti- mation algorithms. Furthermore, the benefit of a Kalman filter for real-time estimates of extended maneuver parameters is critically reviewed in terms of mission operations aspects. An obvious insufficiency in the boost phase modeling has been noted in the radiometric data analysis, that is partially related to attitude control activities. For example, the transfer from Sun Acquisition Mode to the Earth Aquisition Mode prior to the maneuver imposes small velocity components on the spacecraft orbit that are visible in the tracking data residuals. Using EUTELSAT Hot Bird 1 tracking data, the ODEM capabilities of modeling and estimating instantaneous impulsive maneuvers in addition to the extended maneu- ver, are applied to analyse the impact on the data residuals and the extended maneuver estimates.