Reduced Geometric Model of Sentinel-3A for Radiative Thermal Simulation

Radiative thermal simulation of spacecrafts is a time-consuming and difficult process, even more challenging with geometric models becoming more complex. Furthermore, a need for real-time simulation of unpredicted scenarios has been growing in the industry, notably for the development of digital twins. As part of the rationalization of thermal simulators for operations project, result of a partnership between Dorea/Thales Alenia Space and the European Space Agency/French National Centre for Space Studies, the development of a thermal digital twin of the Sentinel-3A satellite from the Copernicus Programme is investigated. To tackle this subject, reduced geometric models obtained through mesh simplification algorithms coupled with numerical simulations are explored and validated for multiple configurations. The simulations consider albedo and Earth fluxes for low Earth orbit (LEO), as well as specular and diffuse radiations. Parallelization of external fluxes is depicted and implemented. Computation times and accuracies for reduced models are compared with reference calculation cases, highlighting numerical speedups. Moreover, the possibility to obtain and use different reduced models depending on the simulation is discussed (for instance one for the solar fluxes and one for the albedo and Earth fluxes). This study highlights the technological bottlenecks and compares the results obtained with ESATAN software used as reference. Finally, conclusions are drawn, and future work are elaborated.