Investigations of the evolution of optical characteristics and dynamics of proper rotation of uncontrolled geostationary artificial satellites Original Research Article

On the base of the photometrical data an analysis of the periods and light curves of the uncontrolled artificial satellites was performed. The equipment used in the observations of the satellites is fast photoelectrical photometer attached to the astronomical telescopes of the Sayan observatory (operated by the ISTP SB RAS). Two-mirror Cassegrain telescope with 0.5 m aperture equipped photoelectrical photometer setup in the fast photometry mode have the ability to track the slow moving objects up to 15-th visual magnitude. The observations started from the second half of the 20-th century and have been continued up to the present time. The standard photometric Johnson-Morgan system UBVR had been used. The basic goals are to present observational data and both discuss the probability of detection of design changes of satellite being a long time in geostationary orbit, and display the periods behavior rarely discussed in the literature. A systematization of the rotation periods is submitted. The light curves of the uncontrolled objects has periodic structure and specific mirror spike features which are a characteristic for identification of an object. Analysis of the standard color index (CI) value can provide additional data on the mirror spike origin. When mirror spikes are eliminated color indexes (B–V) for the diffuse component of the satellites is in the range of 0.9–1.1 and exceed those for the solar type star. Unlike, mirror spikes CI (B–V) are close to zero or negative, indicating a blue excess of radiation spectrum. The processes of the variation rotation periods connected with the satellites construction and their interaction with space environment are discussed.