V.A. Bondarenko, V.G. Mitrikas, A.M. Nosovskij, V.V. Tsetlin, V.I. Kuzmin, A.F. Gadzaov, D. L. Tytik

An analysis of the fluctuation of characteristics of the radiation environment on Mir station was performed in the period from 1986 to 1999. Inside the station, crews are constantly affected by waves of cosmic ionizing radiation. The cosmic background radiation on orbits of piloted space vessels, regardless of its intensity, is an inescapable adverse factor for all living earth organisms. Ensuring radiation protection during a cosmic flight is a major challenge when it comes to maintaining crew members' health. Today, a great deal of experience has been amassed in controling the radiation environment (RE) on board the Mir and ISS orbital stations, using standard dosimetry equipment capable of tracking radiation en-vironment parameters in real time. Identifying correlative relationships between the geo- and helio-physical parameters and the radiation environment on the station is a current challenge for forecasting. However, no clear relationships or consistent functional patterns have been established. One way to solve this problem is to find periodic patterns in geo- and helio-physical parameters affecting the RE on orbital cosmic stations. This is the aim of this study. The results of measuring parameters controlled for when providing for the radiation safety of cosmonauts are time sequences that represent a composition of slow and rapid movements determined by various mechanisms for forming detected signals. The general problem of analyzing various measurement results, in the form of fluctuations and trends, lies in the need to isolate fluctuations such that the results of trend elimination do not impact the structure of the fluctuations. As a rule, fluctuation analysis is performed on the basis of determining the parameters of functions with the given structure. Eliminating fluctuations from the reference series by smoothing out the progression by isolated almost-periods makes it possible to determine the trends' characteristics. It was determined that the fundamental period, that is presented in the basic set of data, is equal to 27-28 days, and is approximately equal to the period of revolution of the Earth-Moon system around the center-of-mass of this system. Individual almost-periods correspond to values that are close to orbital periods around the Sun: of Mercury (88 days), of Venus (224.7 days), of the asteroid belt (from 1600 to1700 days). In the time of crossing of South Atlantic Anomaly zone (ЮАА) by Mir station, periodicity, corresponding to the tropical year, displays clearly in the geomagnetic activity index (Ap) and in values of average density of the atmosphere.