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Browsing by Issue Date, starting with "2018-12-13"

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  • Prototype of a Conversational Assistant for Satellite Mission Operations
    Publication . Gonçalves, Ana Pedro Ferreira Gomes Portela; Guerman, Anna; Nogueira, Tiago
    The very first artificial satellite, Sputnik, was launched in 1957 marking a new era. Concurrently, satellite mission operations emerged. These start at launch and finish at the end of mission, when the spacecraft is decommissioned. Running a satellite mission requires the monitoring and control of telemetry data, to verify and maintain satellite health, reconfigure and command the spacecraft, detect, identify and resolve anomalies and perform launch and early orbit operations. The very first chatbot, ELIZA was created in 1966, and also marked a new era of Artificial Intelligence Systems. Said systems answer users’ questions in the most diverse domains, interpreting the human language input and responding in the same manner. Nowadays, these systems are everywhere, and the list of possible applications seems endless. The goal of the present master’s dissertation is to develop a prototype of a chatbot for mission operations. For this purpose implementing a Natural Language Processing (NLP) model for satellite missions allied to a dialogue flow model. The performance of the conversational assistant is evaluated with its implementation on a mission operated by the European Space Agency (ESA), implying the generation of the spacecraft’s Database Knowledge Graph (KG). Throughout the years, many tools have been developed and added to the systems used to monitor and control spacecrafts helping Flight Control Teams (FCT) either by maintaining a comprehensive overview of the spacecraft’s status and health, speeding up failure investigation, or allowing to easily correlate time series of telemetry data. However, despite all the advances made which facilitate the daily tasks, the teams still need to navigate through thousands of parameters and events spanning years of data, using purposely built user interfaces and relying on filters and time series plots. The solution presented in this dissertation and proposed by VisionSpace Technologies focuses on improving operational efficiency whilst dealing with the mission’s complex and extensive databases.
    2018-12-13Master thesis Open access Show more
  • Project and Validation of an Electromagnetic Field Generator for MECSE CubeSat under Controlled Environment
    Publication . Ferreira, Paulo Jorge; Guerman, Anna; Figueiredo, Paulo de Vasconcelos; Espírito Santo, António Eduardo Vitória do; João, André
    One of the major concerns of the descent phase of spacecraft missions are problems on communication with spacecraft that appear during its atmospheric re-entry. While the spacecraft moves at hypersonic velocity with respect to the atmosphere, the air is compressed and heated, generating a shock wave in front of the vehicle, and a plasma layer around it. As the spacecraft moves towards the planet, this plasma layer becomes increasingly dense causing communications disruption, significant attenuation or even total communications blackout. Applying the magnetic window method which suggests the use of a static magnetic field to open communication window, it is possible to manipulate the blackout. This dissertation is dedicated to the analysis of the payload for MECSE CubeSat mission currently under development in Portugal by a joint team of the UBI (University of Beira Interior) and CEiiA (Centre of Engineering and Product Development). The mission goal is to perform several measurements of the properties of the plasma layer around a 3U CubeSat and to manipulate these properties generating a static magnetic field on board. In order to manipulate the plasma layer, an analytical, numerical, and experimental study is performed to examine the behavior of the magnetic field (B), as a function of the distance from the magnetic field generator to the spacecraft surface. The strength of the magnetic flux density decreases as it moves away from the surface of the model, converging to a neutral state equal to zero. The FEMM 4.2™ open source software is used to create a model of an axisymmetric generator that provides 0.0375 tesla at a distance of 25mm from the generator surface; the configuration is selected to reduce the power demand. In the design phase, materials with high permeability for the core (Pure Iron) and for the winding with high conductivity (Copper Wire) are considered. The number of turns and current determine the magnitude of the magnetic flux density. Analysis of the construction and design parameters, in order to determine the final mass of the generator, matching MECSE CubeSat Experiment mass requirements (3U under 4 kg and 1,2 kg for the payload). After the design, a laboratory model is built, and the magnetic field is measured in different locations in order to validate the analytical model of the generator mass determination and FEMM 4.2™ software for magnetic constraints. Finally, this dissertation discusses the possibility to mitigate the blackout by creating a robust magnetic field generator capable to fit in one unit of the 3Us of the MECSE CubeSat.
    2018-12-13Master thesis Open access Show more