Development of a tool for thermal analysis of small spacecrafts.

Recent years have seen a growing interest in space missions involving small satellites. This attraction is due to their relative ease of production, low cost and short development time, making them accessible to a wide range of organizations, including universities, research institutes and commercial entities. Ensuring the reliability of these systems is becoming increasingly important, with thermal analysis and thermal design in particular playing a crucial role in all phases of project development to keep each satellite component within temperature limits to ensure proper operation. This thesis aims to develop a tool implemented in the MatLAB® environment, known as the Small Satellites Thermal Tool (S2T2), created by the Department of Mechanical and Aerospace Engineering at the Politecnico di Torino. The tool provides support for both thermal analysis and design in the early phases of a space project. In particular, this thesis focuses on the Geometric Math Model (GMM), whose scope is to provide a geometric representation of the satellite, defining its surfaces, node distribution, assigning optical and mechanical properties to each component and calculating the radiative coupling between the spacecraft surfaces. The GMM is the first step in building the satellite's thermal model. To make the tool comparable with commercial software, several improvements have been made to the GMM. New 2D and 3D geometries were implemented and the capability to model deployable solar panels has been introduced. This expansion enables a more comprehensive representation of the satellite's configuration, supporting detailed thermal analyses. In order to improve the accuracy of radiative heat exchange calculations between surfaces, the concept of reflection has been introduced within the Monte Carlo Ray-Trace method for determining the view factors. In addition, efforts were made to make the code modular and more efficient, facilitating integration with future work. The GUI of the GMM module was also modified to improve ease of use. To verify its reliability, the tool was tested and compared with results obtained from Thermal Desktop by Cullimore & Ring Technology, a commercial software widely used in the space industry. As a case study, the tool was used in the early stages of the Spei Satelles space mission to support design decisions.