The I/R Thermal Balance Test of Radarsat-2: Approach to Verification / Correlation 2005-01-2988
Radarsat-2 is a commercial Synthetic Aperture Radar satellite for earth observation.  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. Nevertheless, a good compromise has been chosen between test set up complexity and orbital condition replication: a thermally representative test able to provide suitable verification of the S/C thermal performance.
The objectives of the thermal balance testing (TBAL) of RADARSAT-2 are:
Correlation of the Thermal Mathematical Model (TMM) TBAL temperature predictions to the test results;
Validation of the heater/thermistor/thermostats thermal design (sizing and operation);
Verification of thermal control operation and comparison with the TMM predictions.
The completion of the correlation exercise will allow the validation of the Thermal Mathematical Model and the refinement of final flight predictions.
The paper will mainly describe the Radarsat-2 Thermal Balance test conditions and the relevant analysis correlation that followed the test, as performed at David Florida Laboratory (Ottawa - Canada) in January 2005 (see also [2,3]).
Moreover, a comparison of the correlation approach and results with the Alenia Spazio experience achieved on previous programs will be provided and discussed.