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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.
photometry --- space debris --- star trackers --- modelling --- Space situational awareness --- optic sensors --- Ingénierie, informatique & technologie > Ingénierie aérospatiale
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The exchange of orbit information is becoming more important in view of the increasing population of objects in space as well as the increase in parties involved in space operations. The aim of this thesis was to investigate how orbit information maintained by a space surveillance system can be provided to its users. Services like collision avoidance require very accurate information, while other services might be less stringent. An approach was studied, which allows to derive orbit and covariance information of predetermined accuracy from a reference orbit. Using Chebyshev polynomials, continuous state vector and covariance matrix information can be provided. The major advantage is that no inter- or extrapolation on the user's side is required. A method to reduce the data amount by interpolating the variance envelope functions was also studied. The proposed method in this thesis gives access to highly accurate information from the catalogue, where this information is required. On the other hand it can also provide less accurate information, where requirements are less restrictive, thereby allowing for a significantly reduced amount of data to be transferred and stored.
Orbital mechanics. --- Computers. --- Computer systems --- Cybernetics --- Machine theory --- Calculators --- Cyberspace --- Automatic computers --- Automatic data processors --- Computer hardware --- Computing machines (Computers) --- Electronic brains --- Electronic calculating-machines --- Electronic computers --- Hardware, Computer --- Astrodynamics --- Mechanics --- Orbits --- space debris --- space surveillance --- space situational awareness
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