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Sciamachy is a Dutch/German Earth Observation Instrument on the European Envisat satellite, which was successfully launched on March 1st, 2002. The goal of the instrument is to observe concentrations of trace gases in the atmosphere. Due to the required optical accuracy of the instrument special thermal control methods have been incorporated in the instrument design. Amongst these are the active thermal control loops for the optical bench module. The optical bench module is therefore provided with three feedback-controlled heater loops. During the commissioning phase, the active thermal control systems in the instrument have been characterised in order to optimise their use during the operational phase of the instrument.

Sciamachy is a Dutch/German Earth Observation Instrument on board of the European Envisat satellite, which was launched on March 1st 2002. The goal of the instrument is to observe concentrations of multiple trace gases in the upper atmosphere. Due to the character of the instrument special thermal control methods have been incorporated in the instrument design. Amongst these are the active thermal control loops for the detector modules and the optical bench module. The 8 detector modules, which are cooled with a passive cooler to circa 150 - 240 K, are stabilized with three heaters that are controlled via telemetry. The optical bench module is provided with three feedback-controlled heater loops.

This paper describes the design and qualification of this SCIAMACHY Radiant Cooler and focuses on the methods and results of the thermal balance and thermal verification test of the Radiator Reflector Unit flight model, performed late summer 1998. A new type of temperature control has been used that proved to increase speed, simplicity and accuracy of the test itself as well as the evaluation afterwards. The RRU TB/TV test was successful in gathering all significant thermal parameters. After refurbishment of the cooler door and a requalification test of its transient performance all cooler parameters are acceptable and its thermal performance is within specification.