Master thesis and internship[BR]- Master's thesis : Modeling photometric detection of space debris for a star-tracker-based space situational awareness network[BR]- Internship

Abstract

This thesis contributes to the global efforts of space debris mitigation and monitoring by offering a photometric model of space debris in Earth’s orbit with the aim to integrate such a model into arcsec’s star simulator Intergalactic, aiding arcsec’s DeDUST project in the elaboration of a space situational awareness strategy based on star trackers. The model has been elaborated following a thorough review of the current literature body surrounding the photometric representation of spacecraft and their debris. After a mathematical basis has been established, an algorithm was implemented in MATLAB, with the aid of such open-source tools and NAIF’s Spice and NASA’ GMAT. The produced algorithm has been tested against both simulated cases and real photometric measures in order to both validate the model and find an optimal arrangement of its numerical parameters. The produced optimal model has been used to analyze the possible applications for optics-based space debris detection. It was found that a brightness model with a 26.5% specular component allows to most closely estimate the visual magnitude of several bodies of varying nature and size. The model’s limitation has been identified with respect to an object’s size-to-distance from the sensor (d to R) ratio. Indeed, when (d/R)^2 ≤ 1.5 × 10^−13, the model provides a visual magnitude estimation with a maximum of 10% error, and a maximum of 20% error for 1.5 × 10^−13 ≤ (d/R)^2 ≤ 1.5 × 10^−12. An inspection of the model’s response has confirmed the DeDUST project’s aim to detect debris down to 3 centimeters in size to be a perfectly realizable task. In fact, it was found that a debris detecting system based on arcsec’s Sagitta star tracker is bound to have an operating range of at least 10 kilometers for small untracked debris of 3 to 10 centimeters in size. It was also confirmed that the debris is most likely to appear as streaks to a star tracker rather than a singular and well-defined object. Ultimately, this thesis proves as an enlightening tool in the elaboration of space-debris detection strategies as well as completes the existing body of literature by focusing on the intricacies of space debris photometry.