balance, that is, the absorption and release of heat [9]. The main means of heat exchange are convection within the hermetic volumes and thermal conductivity in adjoining compartments of the spacecraft, absorption of heat radiated by the Sun, reflected by Earth, etc., radiation into space, and convective heating by the streams of the thermal regulation system of the docking spacecraft, and thermal conductivity through its docking assembly in the docked state. To insure an acceptable range of temperatures the following measures and equipment are used: 1) thermal insulation; 2) implementation of external surfaces with specific optical characteristics; 3) thermostatic control of the hydraulic circuits of the thermal regulation system; 4) electrical heating; 5) favorable change in the orientation of the spacecraft. In terms of the acceptable range of temperatures of the docking device and properties of heat exchange, there are three main stages of flight: 1) autonomous; 2) just before docking; 3) in a docked state. In autonomous flight heat exchange may be changed over a wide range. For orbital flights it depends substantially on illumination conditions and the orientation of the spacecraft. Extreme values of temperature of the basic elements of the docking device are determined to a great extent by external heat exchange, which for open surfaces depends on their optical characteristics: the coefficient of absorption of solar energy and reflection . Usually attempts are made to minimize external heat exchange. The external surfaces (except for interacting elements) of domestic docking devices, as a rule, are insulated with multi-layer screen vacuum insulation. As a result the main external heat exchange occurs through the joint surface and open elements of the docking mechanism (the rods, ring with guides, etc.). To reduce heat exchange through these surfaces attempts are made to minimize the values of coefficients and Parts made of alloy AMg6 may be subjected to chemical polishing, . The hulls of docking devices of the Soyuz-Salyut complex are processed in this way. During long illumination by the Sun the temperature is defined mainly by the ratio . Thus, parts with surfaces with are heated to more than 100*C. To decrease the maximum temperature it is expedient to make close to one. The hulls of the APDAs are subjected to chemical polishing and anode oxidation . Overall, the use of screen vacuum thermal insulation and the
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