Evolutionary Insights into the State-of-the-Art Passive Thermal Control Systems for Thermodynamic Stability of Smallsats

Abstract

‘Smallsats,’ originated in the 1990s and popularized again since 2005, is a newly emerging miniaturized form of conventional satellites. Characterized by low mass (usually under 500 kg) and compact dimensions, Smallsats are one of the most sought-after forms of satellites, thanks to the ease offered by the lightweight. However, this privilege brings with itself the significant impediments such as excessive heat generation arising from the compact stature during peak hours of operation, external heat load as a result of radiation. These heat loads manifest themselves as the direct solar flux, earth’s albedo, and earth’s infrared radiation. Sudden temperature drop within the eclipse region results in the permanent-equipmental damage of the electronic circuitry involved, the direct consequence of which is the out-of-tolerance performance of the satellite. Thermal Control Systems (TCS) is the most plausible solution in this regard whose chief objective in any spacecraft or a satellite is to maintain all the subsystems along with the payload components within the stipulated temperature limits for each mission phase. This paper presents the passive thermal control systems (PTCS) in cube-sats. Starting with the discussion of the thermal environment, typical concepts like albedo, earth IR are shed light on. Subsequent discussions follow the study of thermal surface finishes and multi-layer insulations (MLI). Finally, the applications of phase-change materials (PCM) in thermal control systems of cube-sats are introduced. The constant trade-offs between the optimal thermal finish and the overall performance, arising due to incurrence of contamination during synthesis, SLI-MLI thickness and cost associated with increasing thickness and the phase-change materials (PCM’s) and their compatibility, have always been at the pin-point of the research. The widespread importance of thermal control systems is attributed to its ability to ensure the meetings of the gradient requirements, a parameter playing a crucial role in spacecraft dynamics.