Thermal Management of Cubesat Subsystem Electronics

Abstract

The temperature field of an electronic optical instrument can affect the image quality realised by the instrument and, in extreme cases, lead to damage. This is particularly true for instruments operating in harsh environments such as space. The hyperspectral imaging optical instrument (OI) designed for the Intuition-1 (I-1) nanosatellite, currently in low Earth orbit, has been subjected to a numerical analysis of its thermal state under different operating conditions, and some preliminary experimental tests have been carried out to determine the maximum operating temperatures of its sensitive components and the risk of thermal damage. This work was part of a testing campaign prior to the deployment of Intuition-1. Three operational cases were analysed: (1) behaviour in the Earth’s atmospheric conditions when the OI is pointed at the Sun, (2) the end of the de-tumbling process in orbit with the Sun crossing the diagonal of the OI’s field of view, and (3) identification of the maximum possible number of consecutive Earth imaging cycles in orbit. The ultimate goal of this work was to validate the numerical approach used for these cases and to deepen the understanding of the thermal safety of the CMOS image sensor placed in the OI. For these cases, transient thermal field analyses were performed for the OI to determine the temperature distribution and its variability in the most thermally sensitive CMOS image sensor. The components of the OI and its overall structure were experimentally tested, and the results were used to validate the numerical models. The study showed that the built-in temperature sensor does not always reflect the actual CMOS temperature, and in some extreme cases the current temperature monitoring does not ensure its safe operation.