The real attitude motion of the spacecraft Progress M-20M in the mode of gravitational orientation

We reconstructed the uncontrolled attitude motion of the spacecraft Progress M-20M in the mode of single-axis gravitational orientation (gravitational orientation of a rotated spacecraft). In this mode, the spacecraft rotated around its longitudinal axis with the angular rate $0.1\div0.2$ deg./s, the axes being oscillated near the local vertical. The oriented motion lasted for a few orbit revolutions. The reconstruction was made using measurements of the spacecraft angular rate. The measurement data, collected in a time interval about 7 hours, were processed simultaneously by statistical methods and integration of the spacecraft attitude motion equations. The estimations of the mathematical model parameters and initial conditions of the attitude motion were obtained as a result of such processing. The results of reconstruction were checked by measurements of the electric current from the spacecraft solar batteries. We reconstructed the motion in three time intervals in February 2014. The gravitational orientation mode of Progress M-20M was realized for preparation to the experiments with convection sensor DACON-M.