La réduction des budgets du domaine spatial et les missions scientifiques traditionnelles ayant des coûts et une complexité croissants a amené la communauté scientifique à se concentrer sur les petits satellites qui fournissent non seulement des résultats scientifiques de valeur, mais permettent aussi de nouvelles applications dans le domaine de la télédétection, de la surveillance environnementale et des télécommunications. De plus, le concept de vol en formation de petits satellites est une technologie-clé pour beaucoup de missions spatiales futures, en améliorant la capacité de survie et réduisant le coût des missions. Ce travail de recherche a un double but : la proposition de modèles innovants de constellations de nano-satellites et de nouvelles approches de routage pour les réseaux de nano-satellites. Cette thèse propose et analyse trois modèles de constellations de nano-satellites dénommés NanoDREAM, NanoiCE et NanoSPHERE, qui fournissent des services de télécommunications aux régions éloignées. Le modèle NanoDREAM est conçu pour le Désert Salar de Uyuni en Bolivie, une région qui détient 70% de la réserve mondiale de lithium. Le modèle NanoiCE est destiné aux Régions Polaires, pour satisfaire les besoins de télécommunications de la communauté scientifique. Le modèle NanoSPHERE est conçu pour fournir une couverture globale de la Terre pour un marché de télécommunications concurrentiel. De plus, nous avons proposé une architecture pour le segment terrestre basée sur la technologie sans fil. Cette architecture a été déployée sur la zone d'exploitation du Désert Salar de Uyuni. Ces modèles ont été développés analytiquement et mis ensuite en œuvre dans le simulateur SaVi afin d'identifier la meilleure constellation satisfaisant les requis de la mission en terme de couverture et en réduisant au minimum le nombre de nano-satellites de la constellation. […] / The growth in cost and complexity of traditional scientific missions along with the reduction in space budgets have determined space community to focus on small satellites that not only provide valuable scientific returns, but also allow completely new applications in remote sensing, environmental monitoring and communications. Furthermore, small satellite flying in formation is a key technology for many future space science missions, by improving mission survivability and reducing mission costs, and offering multi-mission capabilities, achieved through reconfiguration of formations.The main goal of this thesis is two-fold: proposing innovative nanosatellite constellation models andnew routing approaches for nanosatellite network telecommunications. Therefore, this research work proposes and analyzes three models of nanosatellite constellations, named NanoDREAM, NanoiCE, NanoSPHERE, that provide telecommunication services to remote regions of the Earth. NanoDREAM mode! is designed for Bolivia's Salar de Uyuni Desert, a region which detains 70% of the global lithium reserve. NanoiCE model is intended for Polar Regions, in order to meet the voice and data transfer needs of the entire Antarctic and Arctic scientific community. NanoSPHERE is aimed to provide global coverage in the context of a robust telecommunications market. Additionally, a ground segment architecture based on wireless technology and deployed over the exploitation area of Salar de Uyuni Desert was proposed. Moreover, two new methodologies were proposed: the first one is a method for estimating the number of nano-satellites needed to cover a specific region was, and the second one is a Markov modeling­ based method for evaluating the performance of nanosatellite constellations. [...]

A deorbiting drag device is being designed and built by the University of Toronto Institute for Aerospace Studies/Space Flight Laboratory (UTIAS/SFL) to be demonstrated on the Canadian Advanced Nanospace eXperiment 7 (CanX-7) satellite. CanX-7 will address the growing issue of space debris by designing a drag sail device that will be demonstrated for cubesat-sized satellites. Mission analysis done to ensure the drag device functions properly and deorbits within the required lifetime is performed while varying different properties such as drag coefficient, effective drag area, and solar cycle variations. The design evolution of the device is documented and the chosen design, along with several stages of prototyping, is described. The individual components that make up the device are described as are preliminary numerical analyzes. Finally, the test plan required for the device is described with several deployment experiments and risk reduction tests documented.

A deorbiting drag device is being designed and built by the University of Toronto Institute for Aerospace Studies/Space Flight Laboratory (UTIAS/SFL) to be demonstrated on the Canadian Advanced Nanospace eXperiment 7 (CanX-7) satellite. CanX-7 will address the growing issue of space debris by designing a drag sail device that will be demonstrated for cubesat-sized satellites. Mission analysis done to ensure the drag device functions properly and deorbits within the required lifetime is performed while varying different properties such as drag coefficient, effective drag area, and solar cycle variations. The design evolution of the device is documented and the chosen design, along with several stages of prototyping, is described. The individual components that make up the device are described as are preliminary numerical analyzes. Finally, the test plan required for the device is described with several deployment experiments and risk reduction tests documented.

This thesis aims to design a reliable CubeSat platform, including the avionic subsystems that can sustain a high radiation environment for a mission having a lifetime of at least six months. The science instruments put stringent requirements on the platform to achieve and maintain the desired spin rate. The simulation background is set up in Systems Tool Kit (STK). A trade-off analysis for the Attitude and Orbit Control System (AOCS) of FORESAIL 2 was done, focusing on the actuators and their ability to offer the right amount of torque to fulfill the tether deployment. Mission design analyses were performed to conclude on the form factor of the CubeSat, its ability to generate power, its compliance with the Space Debris Mitigation (SDM) technical requirements, and the total radiation dose accumulated. It was found that a 6U form factor is preferred to allocate more space for each subsystem, alongside with generating enough power for the satellite to work in all modes wanted. The mission is compliant with European Cooperation for Space Standardization (ECSS) and International Organization for Standardization (ISO) standards if the CubeSat is to be launched in September 2022. To allow a threshold limit of 10 krads on the components of the satellite, a shielding wall of 7 mm should be implemented on the CubeSat’s structure. Major requirements for the designed mission were written to initialize the investigation on the sensors and actuators. The results showed that only a propulsion system provided the necessary angular momentum to deploy the tether. The lack of magnetic field makes magnetorquers almost unusable in the desired orbit, leaving reaction wheels as the only option remaining to assist the propulsion units. The different analyses and simulations led to a final AOCS configuration composed of five various sensors (Sun sensors, magnetometers, a GPS, an IMU, and housekeeping sensors) for the attitude determination. A propulsion system and reaction wheels will provide the necessary control over the satellite.

This thesis proposes a distributed robust control approach for low-thrust nanosatellite formation flying. The presented control approach is the further development of an already existing approach which combines robust control and distributed control using the consensus approach. The adjustments presented in this thesis are intended to enable the usage of the control approach in nanosatellite missions such as the upcoming NetSat mission. Stability criteria, optimization goals and constraints such as the limited maximum thrust are formulated with the help of Linear Matrix Inequalities (LMIs). In addition, the presented control approach includes methods for exploiting the maximum thrust and for collision avoidance. Due to the design as a distributed controller based on the consensus approach, a satellite formation can be maintained even in the case of the failure of the propulsion system and/or Attitude Determination and Control System (ADCS) of a single satellite. To verify the design of the control approach, simulations of the formation scenarios planned for the NetSat mission are performed with a satellite formation simulation framework based on Orekit and MATLAB®.

Attitude Determination and Control System (ADCS) is often a complex system on-board any  satellite  which  needs  validation  and  testing  to  prove  its  operability  and  verify  its software  compatibility  with  hardware  and  other  subsystems.    One  failure  in  orbit  is extremely expensive in terms of cost and time due to payload preparation and launch. The ideal test bench would be the one that perfectly simulates the space environment and all its main factors such as weightlessness, Earth’s Magnetic Field (EMF), vacuum, neutral particles, plasma and radiation, among others.  The target in this case was the Earth’s Magnetic Field (EMF), solved with a Helmholtz Cage in a Merritt Configuration, and weightlessness, not implemented but analysed in detail where different alternatives are proposed, similar to market solutions.As  derived  from  literature  and  simulations  executed  along  this  M.  Sc.    Thesis,  the Merritt Cage seems beneficial against any other configuration in terms of magnetic field uniformity and effective volume.  After the design and assembly of the test bench, both properties were verified and successfully achieved, despite the lack of calibration, not executed because of time limitation, and tiny issues encountered along the full evolutionof the project. / Attitude Determination and Control System (ADCS) är ofta ett komplicerat system ombord på alla satelliter som behöver validering och testning för att bevisa dess användbarhet och  verifiera dess  programvarukompatibilitet med  hårdvara och  andra delsystem.   Ett fel  i  omloppsbana  är  extremt  dyrt  med  avseende  på  kostnader  och  tid  på  grund  av förberedelse  och  lansering  av  nyttolast  Den  ideala  testbänken  skulle  vara  den  som perfekt  simulerar  rymdmiljön  och  alla  dess  huvudfaktorer  såsom  viktlöshet,  Earth’s Magnetic  Field  (EMF),  vakuum,  neutrala  partiklar,  plasma  och  strålning,  bland  andra. Målet  i  detta  fall  var  EMF,  löst  med  en  Helmholtz-bur  i  en  Merritt-konfiguration,  och viktlöshet,  inte  implementerad  men  analyserad  i  detalj  där  olika  alternativ  föreslås, liknande marknadslösningar.Som härstammar från litteratur och simuleringar utförda längs denna M. Sc. Avhandling verkar Merritt Cage vara gynnsam mot annan konfiguration när det gäller magnetfältens enhetlighet och effektiv volym.  Efter konstruktionen och montering av testbänken, var båda egenskaperna verifierade och framgångsrikt uppnådda, trots bristen på kalibrering, inte  genomförda  på  grund  av  tidsbegränsning,  och  små  problem  som  uppstod  underprojektets fulla utveckling.

With the increasing number of satellites operating in orbit and the development of nanosatelliteconstellations, it has become more and more arduous for operators to keep track of every satellitestate, and perform corrective or avoidance manoeuvres. That is why CNES, the French space agency,is developing new algorithms, which aimed at making satellites more self-su cient. More especially,these algorithms are in charge of autonomous orbit control, collision risk calculations and satellitestatus monitoring. In this thesis, we present the architecture of these three algorithms and how theyinteract between them to deal with the autonomous control of a satellite. In addition, this paper studiestheir integration within the OPS-SAT nanosatellite, which is an in-orbit demonstrator developed bythe European Space Agency (ESA) and opened to worldwide experimenters. By analysing the dataused by the numerical propagators, the size of the input configuration files sent to the nanosatellitewas optimised. Thanks to this optimisation, the size of telecommands sent during each OPS-SATflyby above the ESOC ground station meets the requirements. Due to some issues encountered with the nanosatellite’s GPS, a solution was found to update thecurrent orbit on-board, and thus allow the proper algorithms’ operation. This thesis also introduceshow the tests were carried out in order to validate these algorithms, both on flat-sat and on the realsatellite. The results demonstrate that their integration on the OPS-SAT numerical environment issuccessful, meaning that the algorithms and their dependences are correctly packaged, sent and uploaded,and that they work as expected. Their execution time are of course longer due to the limitedcalculation capacity of the on-board computer, but are still compatible with real operations, except forthe collision risk computation, which can exceed the orbital period depending on the initial conditions.Finally, the thesis presents the process of real operations for one of the three algorithms developed byCNES, the di culties encountered and the solutions considered. / Med det ökande antalet satelliter i omloppsbana och utvecklingen av nanosatellitkonstellationer hardet blivit mer och mer krävande för operatörer att hålla reda på varje satellits tillstånd och utförakorrigerande eller undvikande manövrar. Det är därför som CNES, den franska rymdorganisationen,utvecklar nya algoritmer som syftar till att göra satelliter mer autonoma. Närmare bestämt ansvarardessa algoritmer för autonom omloppsbanereglering, kollisionsriskberäkningar och satellitstatusövervakning.I detta examensarbete presenterar vi arkitekturen för dessa tre algoritmer och hur de interagerarmellan sig för att hantera den autonoma styrningen av en satellit. Dessutom studeras deras integrationinom OPS-SAT-nanosatelliten, som är en demonstrator i omloppsbana som utvecklats av Europeiskarymdorganisationen (ESA) och öppnad för globala experiment. Genom att analysera de datasom används av de numeriska propagatorerna optimerades storleken på de ingångskonfigurationsfilersom skickades till nanosatelliten. Tack vare denna optimering uppfylls storlekskraven på telekommandonsom skickas under varje passage av OPS-SAT ovanför ESOC-markstationen. På grund av vissa problem med nanosatellitens GPS hittades en lösning för att uppdatera den aktuellaomloppsbanan ombord och därmed möjliggöra korrekt funktion av algoritmerna. Detta examensarbeteintroducerar också hur testerna genomfördes för att validera dessa algoritmer, både på en s.k. flat-satoch på den verkliga satelliten. Resultaten visar att deras integration i den numeriska miljön OPS-SATär framgångsrik, vilket innebär att algoritmerna och deras beroende är korrekt förpackade, skickade ochuppladdade och att de fungerar som förväntat. Deras exekveringstid är naturligtvis längre på grundav den inbyggda datorns begränsade beräkningskapacitet, men är fortfarande kompatibel med verkligaoperationer, förutom beräkningen av kollisionsrisk, som kan överstiga omloppsperioden beroende påde initiala förhållandena. Slutligen presenterar rapporten processen för verkliga operationer för en avde tre algoritmerna som utvecklats av CNES, svårigheterna och de lösningar som övervägs.

A next generation nanosatellite bus is under development at the University of Toronto’s Space Flight Laboratory (SFL), and is being used for the first time in an ambitious Earth observation mission to identify and monitor atmospheric aerosol species. The spacecraft system brings together novel advanced designs that expand the capability envelope of nanosatellites, with heritage SFL technology that is presently defining the state-of-the-art in microspace applications. The work presented in this thesis pertains primarily to the development of the structural subsystem of the Nanosatellite for Earth Monitoring and Observation – Aerosol Monitor (NEMO-AM). Described extensively are the design and analysis efforts made by the author to validate and finalize the structural design in order to bring it to a manufacturing-ready stage. Subsequent work to meet the mechanical requirements of ground operations during the assembly and testing of the spacecraft is also presented.

A next generation nanosatellite bus is under development at the University of Toronto’s Space Flight Laboratory (SFL), and is being used for the first time in an ambitious Earth observation mission to identify and monitor atmospheric aerosol species. The spacecraft system brings together novel advanced designs that expand the capability envelope of nanosatellites, with heritage SFL technology that is presently defining the state-of-the-art in microspace applications. The work presented in this thesis pertains primarily to the development of the structural subsystem of the Nanosatellite for Earth Monitoring and Observation – Aerosol Monitor (NEMO-AM). Described extensively are the design and analysis efforts made by the author to validate and finalize the structural design in order to bring it to a manufacturing-ready stage. Subsequent work to meet the mechanical requirements of ground operations during the assembly and testing of the spacecraft is also presented.

The lightning is the natural source of electromagnetic radiation. It is an atmospheric electrical discharge.  However, since recent times, it was discovered that there are other types of lightning besides those that are visible to the naked eye. They are called TLEs (Transient Luminous Event) and take place above the clouds during thunderstorms. Distinct classification is applied to the various existing TLEs in compliance with their shapes, size, color, altitude, origin and duration. Thus, all Transient Luminous Events are categorized to the following types: elves, spites, halos, blue jets, blue starters, gigantic jets, trolls, gnomes, pixies and ghosts. TLE investigation missions are important for several scientific purposes. They allow to gain an understanding of the lightning creation processes, contribution on global electric circuits as well as chemical influence on the Earth’s climate.  TLE observations can be performed by lightning detection and location systems which differs according to their location. They can be ground-based, space-based as well as carried on aircraft or balloon. Lightning location systems in space are usually conducted on large-, medium- or micro-sized satellites.  The main scope of this thesis is to explore and describe all possible and known methods and techniques of TLE investigation as well as discussions of gained observation results for better understanding and further analysis of more suitable instruments for TLE detection mission on LEO orbit. Analysis of suitable equipment will be done according to the conclusion made from considered lightning detection systems with similar missions and pursuant to nanosatellite requirements.