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The Envisat spacecraft has a launch mass greater than 8.0 tonnes and external dimensions of 10.0 metres x 2.8 metres x 2.1 metres. Due to it’s large size, it was necessary to perform the thermal balance and thermal vacuum testing in two stages. Firstly, there was the testing of the Service Module and, secondly, the testing of the Payload Module (PLM). This paper discusses the thermal balance testing of the PLM. The PLM, itself, is 7.5 metres tall; too large to fit into a test facility solar beam. Originally, it was intended to conduct two solar beam tests; one for the upper part and the second for the lower part. Following a revision and re-scheduling within the programme, it was decided to perform a single, non-solar beam, thermal balance test. The thermal balance test would be performed using test specific, electrical, heaters and test facility shroud control.

The European Polar Platform is a remote sensing satellite with the primary objective in the ENVISAT-1 Payload configuration to monitor and study the earth and its environment. The platform thermal design is passive, assisted by heaters. The ENVISAT-1 Payload consists of several instruments which are responsible for their own thermal control and are required to be thermally decoupled from the platform. ENVISAT-1 platform thermal analyses are performed at various levels: system module instrument unit/subassembly The paper describes a typical system thermal analysis campaign in terms of: geometrical and mathematical models used configurations (e.g. stowed, deployed appendages) and attitudes (e.g. nominal, safe mode) analysed analysis content and results Specific aspects of the system analyses are discussed e.g. complexity of system model which is an assembly of several models established by different companies.