Reconstruction of spacecraft attitude motion by Kalman filtering

Monitoring of quasi-steady accelerations onboard last spacecraft of the Foton series was realized in the following way. First, we reconstructed a real spacecraft attitude motion in a time interval of interest by measurements of onboard sensors. Then we calculated an acceleration at a given point of the spacecraft body along the found motion by the well-known formula. The attitude motion was reconstructed by the least squares method and represented by a solution of spacecraft motion equations. The time intervals, on which the equations allowed an adequate reconstruction, had a length from 1 to 5 orbit revolutions. The length was increased together with the module of spacecraft angular rate. To obtain the acceleration picture during the whole flight, we carried out the reconstruction in several tens such overlapped intervals. In this paper we reconstruct the motion in intervals of an arbitrary length using Kalman filtering. This technique is based on the new variant of realization of the least squares method for reconstruction of the spacecraft attitude motion by onboard measurements of the Eatrh magnetic field. We compare the results obtained by these two techniques in processing the data of the Foton M-3 flight.