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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 ARTEMIS (Advanced Relay and TEchnology MISsion) satellite represents the first element of the Data Relay and Technology Mission Programme (DRTM) developed for the European Space Agency by Alenia Aerospazio (Italy) as the prime contractor. Although using conventional design features and limited mass, power, telemetry and tele-command budgets, the thermal control of the satellite matches the demands dictated by the peculiarities of the ARTEMIS mission such as the significant overall dissipation, the wide spectrum of payload operational scenarios and the relatively unbalanced distribution of payload equipment dictated by system and payload performance considerations. This paper describes the thermal control design solutions with special regard to consideration on ground testability of the system; the analytical approach to predict on-orbit thermal response; the policy adopted in terms of margins and analytical uncertainties.