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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.

This paper describes the thermal design and analysis of RADARSAT-2, a commercial Synthetic Aperture Radar (SAR) satellite for earth observation. The particular thermal design challenges faced by RADARSAT-2 are the continually varying thermal environment imposed by its dawn-dusk, sun-synchronous orbit and the wide range of operational capabilities of the SAR payload. The SAR antenna is a 15m active array design that incorporates 512 transmit/receive (T/R) modules distributed throughout the antenna panels. The thermal environment for these high-dissipation units must be maintained throughout the various mission configurations. The Bus and the Extendable Support Structure (ESS) which deploys and supports the SAR antenna must provide a thermoelastically stable platform from which to mount the SAR antenna as well as the attitude sensors.

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.