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A procedure for predicting thermophysical and thermomechanical characteristics of porous carbon-ceramic composite materials of the heat shield of aerospace craft as functions of the type of reinforcement, porosity of the structure, and the characteristics of the material′s components has been developed. Results of mathematical modeling of the temperature and stressed-strained states of representative volume elements for determining the characteristics of a carbon-ceramic composite material with account taken of its anisotropy have been given.

Abstract. The paper deals with the justification of space antennas reflector layout for advanced telecommunication satellites. The selection of design decisions is based on numerical simulations of heat transfer and mechanics processes characteristic of the geostationary orbit conditions. The advantages of parabolic shell of small thickness reflector scheme reinforced with star-shaped ribs on the convex side are demonstrated.

The procedural error is described for measuring the temperature of a contact sensor with placement within the grooves of an experimental specimen made of ceramic material. Mathematical modelling is performed for the error under specimen one-sided heating conditions. The effect is demonstrated for the error on the result of processing experimental data by means of mathematical processing of nonstationary nonlinear reverse thermal conductivity problems. Recommendations are given for reducing this error.Keywords: procedural error for measuring temperature (PEMT), contact sensor for measuring temperature, thermophysical properties (TPP), reverse thermal conductivity problem (RTP), thermocement based on water glass.In order to plan rocket and space equipment construction it is necessary to have data about the thermophysical properties (TPP) of materials over a wide temperature range. Uncertainty of data about material TPP may lead to an error in design, going beyond permissible temperature limits and loss of operating capacity for onboard equipment and instruments.Recently there has been widespread use of methods for determining TPP in which experimental data are processed by means of software for non-stationary non-linear reverse thermal conductivity problems (RTP) [1]. In processing experimental data it is particularly important to have accurate determination of the temperature field for a material specimen [2]. With use of the most widespread sensors (thermocouples) the procedural error for temperature measurement (PETM) arises due to different optical and thermophysical properties of the specimen sensor material, heat flows through electrodes, contact resistance in the zone of sensor installation, etc.Publications [3 -8] have been devoted to a method for determining the PETM. Before the widespread use of personal computers the error was predominantly determined in analytical form different methods of placing (fixing) sensors and temperature regimes. As a result of this complex dependences were obtained within which there are also such interconnected values as the rate of change in temperature, dimensions, thermophysical and optical properties of test material, and also materials for fastening a sensor and sensor material itself. Practical use of analytical dependences was limited due to the considerable number of functions, simplifying mathematical description of the actual thermophysical processes. In practice only a qualitative estimate of this error was limited, and often it was ignored.With widespread use of personal computers and development of programs for modelling heat exchange processes such as ANSYS, NASTRAN, etc., the situation has changed fundamentally. Work has appeared within which attempts have been made to consider PETM on a real time scale. However, the correctness of methods for fixing heat sensors, properties of the materials used for mounting them, the nature of heat exchange in a complex specimen -temperature sensor system, have not yet been studied sufficiently.The aim of this work included ...

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629.78:620.22 Problems of designing space-antenna refl ectors from composite materials for promising telecommunication satellites are considered. Selection of designs is based on the numerical modeling of heat-transfer and mechanics processes corresponding to orbital-fl ight conditions. Introduction. At present, in our country and abroad, there is active development of systems of space communication using airborne mirror antennas. The continuous growth of volumes and the rise in the importance of information transmitted via satellites are accompanied by higher requirements for the effi ciency and information-handling capacity of communication systems, which leads to an increase in their quantity. The overloading of the geostationary earth orbit with systems of satellite communication and broadcast in the frequency bands C (4.6 GHz) and Ku (11,12, 14 GHz) has become a fact [1]. In connection with this, there has risen interest in systems of satellite communication that work in the high-frequency band Ka (30 GHz). Yet another fi eld of research and developments relates to systems of intersatellite communication covering the frequency band V (40-75 GHz).Together with the increase in the frequency, there are higher requirements placed on the accuracy of the profi le of a mirror-antenna refl ector (MAR), having the shape of a parabolic shell. The permissible deviations of the shape of the MAR surface from a theoretical profi le must not exceed the value Λ/16, and in some cases even Λ/50. For modern communication systems, the permissible deviations are from several millimeters (C band) to fractions of a millimeter (V band). Deviations in the shape of the MAR′s refl ecting surface from the required one occur due to errors made during its manufacture and also in the process of its operation as a result of deformation due to the impact of mechanical and thermal loads. Mechanical loads acting on the refl ector of an antenna installed on a spacecraft are rather low and short-lived, since they occur during changes in the orientation of the spacecraft in outer space and as it conducts maneuvers. It is thermal loads that make the greatest contribution to changing the shape of the MAR′s refl ecting surface: during the fl ight the antenna′s refl ector may get heated unevenly up to +150 o C on the sun-illuminated section of the orbit and cool down to -150 o C or lower temperatures as the spacecraft enters into the shadow of the earth [1].At present, antennas operating in C, Ku, Ka, and V frequency bands are equipped with refl ectors with a solid rigid surface. The signifi cant progress made in the creation of these refl ectors is due to the use of polymer composite materials (PCMs). The refl ector of a mirror antenna must have a small mass, and that means being thin-walled with a low density per unit length, and at the same time it must have a stable shape, i.e., its structure must be quite rigid. Modern MARs with a solid rigid surface (Fig. 1) [2][3][4][5][6][7][8][9][10][11] have an aperture of 0.5-3.5 m. As a rule, they a...

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