Determination of the spacecraft Foton M-2 attitude motion on measurements of the angular rate

The preprint presents the results of reconstruction of the Foton M-2 attitude motion during its uncontrolled flight 31.5 – 16.06.2005. The reconstruction was carried out by processing onboard measurements of three components of the spacecraft angular rate. The measurement data, accumulated on a time interval of 83 min, were processed simultaneously by means of the least squares method and integration of the spacecraft attitude motion equations. The estimates of the mathematical model parameters and initial conditions of the attitude motion were obtained as a result of such processing. The real attitude motion was determined on 12 such intervals. The obtained results gave complete comprehension of the motion during the flight. The motion began with small angular rates, but then it became faster and proved to be close to Euler's regular precession of an axially symmetric rigid body. On 14.06.2005, the spacecraft angular rate around its longitudinal axis was equal 1.3 deg./s, projection of the angular rate vector onto the plane perpendicular to that axis was equal 0.11 deg./s.