Master thesis and internship[BR]- Master Thesis : ARRAKIHS mission: Opto-thermo-mechanical design of the baffle system[BR]- Integration Internship : Centre Spatial de Liège

Abstract

The ARRAKIHS mission is the second fast class mission in the European Space Agency’s Cosmic Vision scientific programme, with the primary objective of investigating unresolved aspects within the Lambda-Cold Dark Matter (LambdaCDM) cosmological model. Specifically, it seeks to explore potential deviations in the behaviour of dark matter from the standard LambdaCDM model. To achieve this, a sample of galaxies, such as the Milky Way, will be observed in the nearby Universe at unprecedented surface brightness and resolution. To capture images of this ultra-low surface brightness sample of galaxies, an innovative instrument must be devised and deployed aboard a mini-satellite in low-Earth orbit. This instrument consists of a binocular telescope assembly equipped with a fore baffle designed to attenuate stray light and achieve the required resolution.

This thesis details the iterative process involved in the preliminary design of the telescope's baffle. Three iterations were carried out, refining the geometric configurations through ray tracing analysis. Initially, the baffle was designed to be suitable for the ARRAKIHS binocular telescope. Subsequent iterations introduced innovations to improve stray light rejection, notably incorporating an internal baffled shield between the two channels of the baffle. Each configuration is compared and discussed to derive the optimal baffle design. In addition to the opto-mechanical design, a preliminary thermal analysis was carried out. It established an operating temperature range for the baffle from 242.4 K to 249.6 K, based on various assumptions within the thermal model. Rigorous discussion and justification of these assumptions ensure the reliability of the thermal analysis results.

This thesis marks a significant accomplishment in the design of the telescope’s baffle for the forthcoming ARRAKIHS mission. The iterative processes facilitated a meticulous study and refinement of the baffle, demonstrating notable improvements in stray light rejection. The insights gained from this research, covering both optical and thermal aspects, will directly influence the development of the final baffle configuration.