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The thermal control design of the Italian Satellite (ITALSAT) has been experimentally qualified by means of a solar simulation test performed on a dedicated structural/thermal model. The test model was thermally representative of the flight unit and all the thermal hardware was flight standard. Thermal analysis in the test conditions have been performed in order to verify the thermal mathematical models of the spacecraft. The paper describes the tested spacecraft model and the test approach. Test results, correlation with predicted temperatures as well as influences of test conditions on spacecraft test temperatures are presented and discussed.

The ITALSAT telecommunication system is based on the operation of two geostationary satellites: the first (pre-operative) launched in January '91 the second (operative) to be launched in '96. The thermal design of the satellites was extensively verified by analysis and test including a Solar Simulation thermal balance on the structural-thermal model and thermal vacuum - thermal balance on flight models. Additionally, on-orbit temperature data from the protoflight model is available for equinox and solstices 24 hr. transients. The results have been statistically processed and compared with test data and correlation analysis in order to provide a reliable background for thermal control design and verification of future similar telecommunication satellites.

Radarsat-2 is a commercial Synthetic Aperture Radar satellite for earth observation. [1] The general stowed configuration is shown in Figure 1. In nominal operation mode, once deployed, the large SAR polarimetric Antenna (i.e. able to transmit and receive both horizontal and vertical polarisations) is inclined of about -29.8° versus the nominal direction of geodetic local surface normal (Right Looking mode). When is necessary to take images of South Pole, nominally not visible from SAR, the S/C must be rotated to the +29.8° position (Left Looking mode). During the Radarsat-2 thermal testing the S/C (PFM) was subjected to a first thermal balance/thermal cycling test in vacuum with simulation of external heat fluxes by means of I/R lamps and additional test heaters. A very complex thermal test configuration was required in order to simulate the continually varying thermal environment imposed by the S/C nominal sun-synchronous orbit and attitude.

Several last-generation and future satellite communication systems require the use of large deployable antennas. A European product in this field is presently not available: in this frame the European Space Agency assigned a contract for the development of the Large Deployable Antenna Reflector for advanced mobile communications (LDA). The project is driven by ALENIA SPAZIO as prime contractor and system designer with the support of other companies: EGS (Russia), HTS (Switzerland), SENER (Spain), Magna (Austria). The Antenna consists of a paraboloid with 12m in projected aperture, 6.3m of focal length and located with a clearance of 3m from the focal axis. From a technical point of view, the LDA project was characterized by several challenging tasks: thermal aspects are outlined in the paper. In particular, the mathematical modeling of the reflector and the optical characterization of its reflecting mesh required particular care.