Investigation of evolution of spacecraft Foton-12 attitude motion

This preprint presents the results of the repeated reconstruction of the uncontrolled attitude motion of the spacecraft Foton-12 (was in orbit 09.09 – 24.09.1999) by measurements of onboard magnetometers. This problem was already solved successfully a few years ago. The repeated reconstruction was made by using the more simple mathematical model of spacecraft attitude motion than the model used in processing just after the flight. Simplifications were made in order the new model corresponded to the models in Beletsky's theory of spacecraft attitude motion closed to Euler's regular precession of an axially symmetric rigid body. The results of processing measurements on 15 short (3.5 hours) time intervals are directly compared with the averaged equations arising in Beletsky's theory. This allowed us to interpret the evolution of the rotational motion of Foton-12 and to explain the occurrence of the motion regime established at the end of the flight.