Speaker
Description
The CHIME (Copernicus Hyperspectral Imaging Mission for the Environment) mission is a key component of the European Union’s Earth Observation program, Copernicus. The mission consists of two satellites carrying a unique payload designed to provide routine hyperspectral observations. To perform these observations, the instrument’s three focal planes will be cooled down to 175 K. The cooling of the focal planes is achieved passively, using a large baffled cryogenic radiator connected to the focal planes by a cryogenic chain featuring three graphite thermal straps and two ethane heat pipes. In 2024, the Structural and Thermal Model (STM) of the HSI underwent thermal balance testing, a crucial step towards the Critical Design Review (CDR) in early 2025. In this article, the results of the STM thermal balance test are presented, including the thermal model correlation and the status of the thermal control design at CDR. During the thermal balance test, the cryogenic chain exhibited higher-than-expected temperatures, prompting an investigation into potential additional heat leak sources within the instrument design and the test equipment. The findings of this investigation are detailed, as well as the performance of the ethane heat pipes under gravity conditions, and the overall results of the thermal balance.
