Determining the Attitude Motion of the Spacecraft Foton M-3 on Measurements of its Angular Rate and the Strength of the Earth Magnetic Field

The paper presents the results of reconstruction of the attitude motion of the spacecraft Foton M-3. The reconstruction is based on processing the measurements of two vectors: the spacecraft angular rate and the strength of the Earth magnetic field. The processing technique uses kinematical equations of the attitude motion of a rigid body. In its framework, the measurement data of both types, collected on a time interval, are processed jointly. The angular rate data are smoothed by trigonometric polynomials and those polynomials are substituted in Poisson kinematical equations for elements of the transition matrix, which transforms the spacecraft coupled coordinate system to the Greenwich one. The equations obtained present the kinematical model of a spacecraft attitude motion. The solution of the equations, which approximates the real motion, is found by the least squares method from the condition of the best agreement between measurement and calculation data of the magnetic strength. The reconstruction was made for 9 time intervals, each interval having the length of 84 min. The results proved to be very close to the results obtained by the technique that uses the magnetic measurements only and the full system of spacecraft motion.