Spacecraft Attitude Determination Using Ground Based Photometry: A Comparison of Estimation Algorithms

Room # EB204

The time history of ground-based photometry measurements, called lightcurves, can be used to determine the attitude of a spacecraft. The extraction of information about the satellite’s attitude is realized through what is called lightcurve inversion. Lightcurve inversion utilizes a filter or an optimization method to extract the information on the desired parameters. The accuracy of the lightcurve inversion performance of three filters is compared. These filters are the bootstrap particle filter, the extended Kalman filter and the unscented Kalman filter. The attitude modes of a controlled spacecraft maintaining an inertially fixed attitude and spinning at constant rates are simulated. When the spacecraft is maintaining its inertial attitude, none of the filters are able to accurately estimate the satellite attitude. However, when the spacecraft was rotating the filterswere able to estimate the attitude for varying degrees of initial conditions. The extended Kalman filter performs as well as the other two filters when the initial attitude uncertainty is low. When the initial attitude uncertainty increases to high levels, the bootstrap particle filter is the only filter able to accurately determine the spacecraft attitude.