Among the various challenges involved in the development of CubeSats lies the attitude determination and control of the satellite. The importance of a properly functioning attitude determination and control system (ADCS) on any satellite is vital to the satisfaction of its mission objectives. Due to this importance, three-axis attitude control simulators are commonly used to test and validate spacecraft attitude control systems before flight. However, these systems are generally too large to successfully test the attitude control systems on-board CubeSat-class satellites. Due to their low cost and rapid development time, CubeSats have become an increasingly popular platform used in the study of space science and engineering research. As an increasing number of universities and industries take part in this new approach to small-satellite development, the demand to properly test, verify, and validate their attitude control systems will continue to increase. An approach to CubeSat attitude determination and control simulation is in development at the Virginia Tech Space Systems Simulation Laboratory. The final test setup will consist of an air bearing platform placed inside a square Helmholtz cage. The Helmholtz cage will provide an adjustable magnetic field to simulate that of a low earth orbit (LEO), and the spherical air bearing will simulate the frictionless environment of space. In conjunction, the two simulators will provide an inexpensive and adjustable system for testing any current, and future, CubeSat ADCS prior to flight. Using commercial off the shelf (COTS) components, the Virginia Tech CubeSat Attitude Control Simulator (CSACS), which is a low cost, lightweight air bearing testing platform, will be coupled with a 1.5-m-long square Helmholtz cage design in order to provide a simulated LEO environment for CubeSat ADCS validation. / Master of Science / The attitude determination and control subsystem is a vital component of a spacecraft. This subsystem provides the pointing accuracy and stabilization which allows a spacecraft to successfully perform its mission objectives. The cost and size of spacecraft are dependent on their specific applications; where some may fit in the palm of your hand, others may be the size of a school bus. However, no matter the size, all spacecraft contain some form of onboard attitude determination and control. This leads us to the introduction of a miniaturized class of spacecraft known as CubeSats. Their modular 10×10×10 cm cube structural design allows for both low cost and rapid development time, making CubeSats widely used for space science and engineering research in university settings. While CubeSats provide a low cost alternative to perform local, real-time measurements in orbit, it is still very important to validate the attitude determination and control subsystem before flight to minimize any risk of failure in orbit. Thus, the contents of this thesis will focus on the development, design, and testing of two separate spacecraft attitude determination and control simulation systems used to create an on-orbit environment in a laboratory setting in order to properly validate university-built CubeSats prior to flight.

The goal of this thesis is to create the phase A design for IceBrain-1's power subsystem. The mission in itself is an AI powered image recognition test platform that will be used to see how much information is needed for an AI to detect different objects from space. To accomplish this the satellite will use two computers to run different algorithms. These are big power consumers and therefore it is important to have a power subsystem that can supply that power and energy. To create this design the platform and its components needed to be selected. To fit the IceBrain-1 payload the 16u platform from GOMSpace has been chosen and thus most components will be from that supplier. To get the power consumption and generation of the satellite, orbital simulations were done in the program 42 whose data was then used in larger simulations in matlab. Where two scenarios were created with different assumptions regarding power usage. The findings of this thesis suggest that the power subsystem is heavily dependant on the runtime of the AI computers. A longer duty cycle will require more batteries for them to fulfil the requirement set by this thesis. More solar panels might also be needed for the satellites end of life. The thesis ends with two proposals for the setup of the satellites power subsystem depending on which of the two scenarios is closer to reality. / Målet med denna uppsats är att skapa en fas A design för IceBrain-1s kraftpaket. Satelliten är en AI driven bildigenkännings-testplattform som ska användas för att se hur mycket information det krävs för att en AI ska kunna identifiera objekt från rymden. För att utföra detta kommer satelliten använda sig utav två datorer som kör olika algoritmer. Dessa har en relativt hög energikonsumtion och kräver därför ett kraftpaket som kan leverera den energin. Designen utgår ifrån GOMSpaces 16u kubsatellitplattform och använder främst komponenter från deras utbud i mån det finns. För att generera data på hur mycket energi som används och genereras så utfördes omloppsbanesimulationer i programmet 42. Datan från den användes sedan i ytterliggare simulationer inuti Matlab där två olika scenarier med olika antaganden hade skapats. Resultatet från arbetet är att kraven på kraftpaketet är till största del baserat på hur länge datorerna kör. Om de är igång en längre tid kommer det att krävas mer batterier för att uppfylla kraven tillsammans med mer eller större solpaneler kan också krävas vid slutet av dess livstid. Två olika kombinationer av solpaneler och batterier kan användas av satelliten baserat på om vilken av de två scenarierna som är närmre verkligheten. / IceBrain-1

The Ram Energy Distribution Detector (REDD) is a new CubeSat-compatible space science instrument that measures neutral wind characteristics in the upper atmosphere. Neutral gas interactions with plasma in the ionosphere/thermosphere are responsible for spacecraft drag, radio frequency disturbances such as scintillation, and other geophysical phenomena. REDD is designed to collect in-situ measurements within this region of the atmosphere where in-flight data collection using spacecraft has proven particularly challenging due to both the atmospheric density and the dominating presence of highly reactive atomic oxygen (AO). NASA Marshall Space Flight Center has a unique AO Facility (AOF) capable of simulating the conditions the sensor will encounter on orbit by creating a supersonic neutral beam of AO. Collimating the beam requires an intense magnetic field that creates significant interference for sensitive electronic devices. REDD is undergoing the final stages of validation testing in the AOF. In this presentation, we describe the LabVIEW-automated system design, the measured geometry and magnitude of the field and the specially designed mount and passive shielding that are utilized to mitigate the effects of the magnetic interference. / Master of Science / The Ram Energy Distribution Detector (REDD) is a new CubeSat-compatible space science instrument that measures winds in near-Earth space. Gas interactions with plasma in the upper regions of the atmosphere are responsible for spacecraft drag, radio wave disturbances, and other phenomena. REDD is designed to collect direct measurements within this region of the atmosphere where in-flight data collection using conventional spacecraft has proven particularly challenging. The environmental testing needed to demonstrate the sensor requires a specialized system located at NASA Marshall Space Flight Center. To simulate the conditions the sensor will encounter on orbit within a laboratory requires exposing REDD to a supersonic beam of gas using NASA’s unique Atomic Oxygen Facility. Forming this gas into a beam requires an intense magnetic field that creates significant interference for sensors such as REDD. Testing in this facility requires a specially-designed sensor mount and magnetic shielding system. REDD is undergoing the final stages of validation testing in the Atomic Oxygen Facility. In this presentation, we describe the computer software-automated system for testing the sensor, the shape and strength of the magnetic field, the specially designed sensor mount, and magnetic shielding that are used to mitigate the effects of the interference.

Les champs radiatifs dans le complexe d’accélérateurs du CERN sont caractérisés par des particules mixtes avec un large spectre d’énergie. Le système de surveillance des radiations, le RadMon, a été développé pour la mesure distribuée, et en temps réel, des radiations et ses effets sur l’électronique installée dans les tunnels et les zones expérimentales. Pendant la première phase d’opération du RADMON, un problème critique a été identifié sur les mémoires SRAM utilisées comme capteurs de fluence des hadrons de hautes énergies. Un large nombre de MCU (Multiple Cell Upsets), générés par des microlatchups, ont commencé à apparaître sur les RADMONs, affectant ainsi la précision de mesure de la fluence. Une étude de la cause de cet effet a été réalisée et une solution utilisant un algorithme de détection et de correction en ligne, embarqué sur un FPGA, a été évaluée et mise en place sur les RADMONs installés dans les zones du SPS, PSB, NA62, HiRadMat, ALICE et CHARM.Par ailleurs, dans le cadre du projet CELESTA, une étude de faisabilité a été réalisée pour valider l’adaptation du RadMon à une charge utile pour des applications CubeSat de dimension 1U. Le travail de recherche a été soutenu par le service de transfert de connaissance du CERN en collaboration avec l’Université de Montpellier, le Centre Spatial Universitaire.Les tests expérimentaux ont été effectués dans le nouveau moyen de test CHARM. CHARM offre la possibilité de reproduire les champs radiatifs mixtes présents dans les installations du CERN ainsi que les basses orbites terrestres (LEO).Un module autonome de charge utile pour Cubesat a été développé et équipé avec des capteurs permettant de mesurer dose ionisante ainsi que la fluence des hadrons de haute énergie. Par ailleurs une expérience permettant de détecter des latchups a été ajoutée au module. Les résultats des tests ont permis la définition d’une nouvelle procédure pour la qualification des nano satellites au niveau des radiations sur le système. Ce travail de thèse détaille l’approche suivie pour le choix et la caractérisation des composants utilisés sur la charge utile.La charge utile de CELESTA est le premier projet du CERN sur le sujet de la science des "small satellites". Il représente la première étape d’un intérêt croissant de l’utilisation du moyen de test CHARM pour des missions en environnement spatial. / Radiation fields in the CERN accelerator complex are characterized by mixed particles with broad energy ranges. A Radiation Monitoring System, called "RadMon", was developed for the distributed, on-line measurement of the complex radiation fields and their effect on the electronics installed in areas with a harsh radiation environment. The most recent version of the RadMon revealed a critical issue soon after deployment in the tunnel and the experimental areas. Multiple Cell Upsets (MCUs) arising from microlatchup events started showing up on the SRAM-based particle flux sensors equipped by the system, ultimately affecting the measurement and resulting in corrupted data and accuracy losses. A study of the generation of this effect was performed, and a solution using an on-line detection and correction algorithm embedded on an FPGA, was evaluated and implemented on the RadMon device.Furthermore, in the framework of the project CELESTA, a feasibility study was carried out to validate the adaptation of the RadMon to a 1U CubeSat payload. The research was supported by the CERN Knowledge Transfer as a collaboration between the University of Montpellier, the Centre Spatial Universitaire and CERN. Experimental tests were performed at the new CHARM facility, which allows the characterization of small components, as well as large systems, in a mixed-field representative of the Low Earth Orbit.A stand-alone payload module for 1U CubeSats was developed and equipped withsensors of ionizing dose and high energy hadron fluence. In addition a Latchup Experiment was added on the module as part of the scientific goals of the mission. Results of experimental tests led to the definition of a new procedure for the radiation qualification of small satellites at system level. Details of the characterization and the choice of components are presented together with the approach followed.The payload is the first small satellite module ever designed at CERN. It representsthe first step of an increasing interest towards radiation qualification at CHARM of electronics for low orbit space missions.

SEAM (Small Explorer for Advanced Missions) is a 3U CubeSat developedat KTH Royal Institute of Technology which will provide highqualityDC and AC magnetic field measurements of Earth’s magneticfield. The measurement system requires extended periods of timeup to 1000 seconds without active attitude control. The satellite willuse passive gravity gradient stabilization and dipole cancellation via aseparate set of magnetorquers to satisfy LVLH pointing requirementsduring the coasting phases. In this thesis a detailed model of satellitemagnetic moment is presented which includes dipole moment sourcesfrom on-board current loops. The attitude dynamics of the satelliteis characterized with simulations and a strategy is proposed to estimateand compensate the time-dependent magnetic dipole momentusing the dipole compensation magnetorquers and an offline estimationalgorithm. The algorithm is tested with simulated error sourcesand noise and was found to be able to robustly identify and cancel outthe satellite dipole to satisfy mission requirements. / SEAM (Small Explorer for Advanced Missions) är en 3U CubeSat utveckladpå KTH Kungliga tekniska högskolan för DC och AC magnetiskfältmätningarav Jordens magnetfält. Mätningar kräver längretidperioder upp till 1000 sekunder utan aktiv attitydstyrning. Satellitenkommer använda passiv tyngdkraftsgradientstabilisering samtmagnetisk dipolmomentkompensation med hjälp av ett separat setav magnetiska spolar för att upprätthålla orienteringskrav under perioderutan attitydstyrning. Denna rapport presenterar en detaljeradmodell av satellitens magnetiskt dipolmoment som inkluderar dipolmomentkällorfrån strömslingor ombord satelliten. Satellitens attityddynamikär karaktäriserad med simulationer och en strategi tas framför att estimera och kompensera det tidsberoende magnetiska dipolmomentetgenom att använda dipolkompensations magnetiska spolaroch en offline estimeringsalgoritm. Algoritmen är testad med simuleradefelkällor och brus och har funnits pålitlig för uppskattning avdipolmomentet och dess kompensation för att uppfylla missionskrav.

Measuring the thrust of cold gas micro-thrusters, due to the small magnitude of the generated force, is a challenging task, and to obtain satisfying quality of results usually careful adjustments of the setup has to be performed. The work presented in this paper aims at improving the quality of such measurements at the GomSpace Sweden company. The work consists of two parts: In the first part the author focuses on improving current thrust measurements setup implemented in the company, which consists of a vacuum compatible laboratory scale. It was observed that the results obtained from this setup were approximately 25‒35% lower than expected. A test campaign performed within the work found that this was associated mainly with backflow of plume expansion gases. Covering the scale and the tested propulsion unit with a box having openings only for thrusters was proved to be sufficient setup upgrade to mitigate the issue. In the second part of the project an alternative setup utilising a hanging pendulum-based solution with strain measurement-based force sensor is proposed and its design is thoroughly described. Results of initial tests of a 3D printed prototype of this setup are presented, proving its potential to produce results with better quality of output than the laboratory scale. / Att mäta dragkraften från mikrodysor baserade på kallgas är på grund av den låga genererade kraften en utmanande uppgift. För att få tillfredsställande kvalitet på resultatet måste vanligtvis noggranna justeringar av inställningarna utföras. Arbetet som presenteras i denna rapport syftar till att förbättra kvaliteten på sådana mätningar vid GomSpace Sweden AB. Arbetet består av två delar: I den första delen fokuserar författaren på att förbättra den nuvarande uppställningen för mätning av dragkraft vid GomSpace, bestående av en vakuumkompatibel laboratorievåg. Det observerades att resultaten från denna mätupställning var cirka 25‒35% lägre än förväntat. En testkampanj som utfördes inom ramen för detta arbete visade att detta främst var förknippat med ett tillbakaflöde av gaser från den expanderande bränsleplymen. Att täcka över vågen och den testade framdrivningsenheten med en låda med öppningar endast för dysan visade sig vara tillräckligt för att minska problemet. I den andra delen föreslås ett alternativt upplägg baserat på en hängande pendel med en töjningsmätningsbaserad kraftsensor, dess utformming beskrivs utförligt. Resultaten av de första testerna av en 3D-utskriven prototyp av denna uppställning presenteras, vilket visar på dess potential att producera mätningar med bättre kvalitet än laboratorievågen.

Beyond Atlas, a company based in Danderyd, Sweden is working on a Low Earth Orbit (LEO) 3U-CubeSat (Cube Satellite) exploration mission. As part of their maiden mission, they aim to validate the navigation, propulsion, and communication techniques of a CubeSat while it performs orbital maneuvers to collect photographs of space debris. This study briefly introduces the Beyond Atlas mission and its CubeSat design. The thesis work then mainly focuses on the details of the Attitude Determination and Control System (ADCS) peripherals and software onboard the CubeSat. It describes the Attitude Determination peripherals such as the sun sensor, star tracker, magnetometer, and gyroscope that will be onboard the CubeSat, followed by the description of the Attitude Control peripherals, namely, the magnetorquer and the reaction wheel. Subsequently, it discusses the hardware’s configuration and interface techniques with the flight computer that specifically caters to the satellite’s attitude determination and control aspect. Finally, it reports a Hardware-in-the-loop (HIL) testing methodology, and the corresponding results obtained from the unit testing of the peripherals and the operational testing (Detumbling and Pointing) of the ADCS of the Beyond Atlas CubeSat. Based on the testing results, the report concludes that the selected hardware for the Beyond Atlas mission, when integrated, can perform the principal functionalities. / Beyond Atlas baserat i Danderyd, Sverige är ett företag som arbetar med ett rymdutforsknings projekt. Som en del av deras jungfruuppdrag används en 3UCubeSat för att validera navigering, framdrivning och kommunikationsningar medan den utför banmanövrer för relativnavigation och tar bilder av rymdskräp. Denna studie introducerar kort Beyond Atlas uppdraget och dess CubeSat-design. Rapporten fokuserar sedan huvudsakligen på detaljerna i ADCS kringutrustning och programvara ombord på CubeSat. Den beskriver attitydkännande utrustning som solsensorer, startracker, magnetometer och rategyro som finns ombord, följt av beskrivningen av attitydst yrenheter, nämligen magnetorquer och reaktionshjul. Därefter diskuteras hårdvarans konfiguration och gränssnitt med navigationsdatorn som dedikerat utför satellitens attitydbestämning och attitydkontroll ADCS. Slutligen rapporterar studien testmetodik av inledande validerings-tester (Detumbling and Pointing) av ADCS i Beyond Atlas CubeSat. Baserat på testresultaten drar rapporten slutsatsen att den valda hårdvaran för satelliten kan utföra de primära navigationsfunktionerna.

Propulsion systems allow satellites to perform many functionalities in space, such as orbital station keeping, reentry control, attitude control, orbital transferring, rendezvous operation, and even more thrilling, interplanetary travel. Indeed, propulsion systems in satellites have fostered a new favourable era of space exploration and application, therefore, detailed processes to operate propulsion systems need to be developed so that space missions, carrying this valuable system, are completed successfully. The aim of this study is to describe the most relevant operating procedures for the cold gas propulsion system NanoProp 3U, developed by GomSpace, on-board the 3U CubeSat MIST satellite developed by KTH. Procedures, such as power levels, telemetry considerations, propellant mass determination, Fault Detection Isolation and Recovery analysis, and decommissioning plan allow proper operation of NanoProp according to the mission requirements determined for MIST mission. Moreover, this study describes detailed mission experiments to be performed with NanoProp with the objective of assessing the performance delivered by the propulsion system itself, and other on-board subsystems which are required for monitoring and controlling the spacecraft according to the effects generated by the propulsion system. The planning and operation of a propulsion system should be outlined on-ground, during the mission design, so a clear understanding of the characteristics and limitations of the system are highlighted towards the development of a secure and solid space mission. / Framdrivningssystem tillåter satelliter att utföra många funktioner i rymden, som t.ex. att hålla konstant avstånd till en annan rymdfarkost, utlösa återinträde i atmosfären, attitydstyrning, manövrera mellan olika omloppsbanor, och, till och med, interplanetära uppdrag. Framdrivningssystem i satelliter har främjat en ny lovande era av rymdforskning och praktisk tillämpning av rymden, och därför behöver detaljerade, men praktiskt hanterbara, metoder för att operativt använda framdrivningssystem utvecklas. Basen för detta arbete är att beskriva de mest relevanta driftsrutinerna för framdrivningssystemet NanoProp 3U, utvecklat av GomSpace, för användning ombord på MIST-satelliten (en 3U Cubesat) som utvecklats av KTH. Aspekter på NanoProps användning i MIST som förbrukning av elektrisk energi, telemetribehov, drivmedelsmassa, hantering av felfunktioner (upptäckt och avhjälpande) och avveckling av satelliten vid drifttidens slut analyseras i detalj. Dessutom analyserar detta arbete hur detaljerade driftprov kan utföras med NanoProp i syfte att bedöma de prestanda som framdrivningssystemet tillhandahåller och hur dessa prov påverkar och stöds av driften av satellitens övriga delsystem. Det övergripande syftet med detta arbete är således att utveckla en metod för att planera driften av ett framdrivningssystem under ett satellitprojekts definitions- och utvecklingsfaser så att en tydlig förståelse av systemets egenskaper och begränsningar leder till ett säkert och stabilt rymduppdrag.

The emergence of small and affordable satellites has led to rapid growth in the number of launched satellites over the past two decades. To save costs, small satellites often use mass-produced electronic components not explicitly designed for the radiation environment of space, which reduces reliability and makes them unsuitable for higher orbits. Improved radiation protection would enable small satellites to operate in high radiation environments and increase their reliability. This work investigates how small satellite electronics can be protected against the high radiation environment of geostationary transfer orbit on the example of the Foresail-2mission. Foresail-2 is a planned 6U CubeSat mission to the Earth radiation belts and is intended to use consumer-grade electronics components. In this harsh environment, most semiconductor devices require radiation shielding. The Space EnvironmentInformation System of the European Space Agency was used to analyse expected particle spectra along the planned orbit through the radiation belts. These particle spectra were then used in Monte-Carlo simulations based on the Geant4 particle transport toolkit to simulate the performance of different shielding configurations. Several thousand multilayer shielding configurations were simulated to optimise the material composition and layer structure of multilayer shielding. The best multilayer configurations against the combined proton and electron spectra of the Earth’s radiation belts use materials with low proton numbers on top of materials with high proton numbers and can significantly outperform conventional aluminium shielding. However, the usage of alternative materials might introduce significant overhead in the design and manufacturing of the satellite structure. Additionally, the influence of satellite structure geometry and openings in the shield was analysed. Even a 1 cm2 opening in the shield can increase the total ionising dose received by electronic components over a mission lifetime by more than an order of magnitude. In conclusion, the work recommends an aluminium body of 6 mm or equivalent multilayer shielding for the Foresail-2 mission to reduce the radiation level to a tolerable level for consumer-grade electronics, while openings in the satellite body should be avoided or covered up with additional shielding. / FORESAIL

This thesis presents the work of adding support for a communications protocol in a space application. The work is a part of KTHs MIST (MIniature STudent Satellite) project which aims at sending an experimental satellite into space. Each experiment on the satellite is designed as a subsystem. These subsystems need to be able to communicate with the main computer on the satellite in order to transfer the results of the experiments down to earth. In efforts prior to the current thesis, a special communications protocol has been specified to solve this problem. That protocol is called MSP (MIST Space Protocol). This paper describes the efforts to add support for MSP to two of the satellite’s experiments. These two experiments are called SiC in Space and Piezo-LEGS. However, since Piezo-LEGS is incompatible with the I2C bus in which MSP runs on top of, it must communicate through the SiC experiment. Which parts of the protocol that need to be supported by each experiment are defined. The result of the work is that the experiments can communicate with the main computer through the MSP protocol. / Denna kandidatuppsats beskriver arbetet med att implementera MSP protokollet för de två experimenten SiC och Piezo-LEGS. Syftet med MIST projektet är att skicka upp en experimentsatellit i omloppsbanan runt jorden. I satelliten finns ett antal experiment. De två experiment som arbetet ar fokuserat på är ”SiC in Space” och ”Piezo-LEGS”. SiC-experimentets syfte är att man ska göra mätningar på en kiselkarbid (SiC) transistor i rymdens vacuum. Syftet med Piezo-LEGS experimentet är att man vill mäta hur prestandan för en piezoelektrisk motor påverkas i rymden. Inom MIST-projektet har ett kommunikationsprotokoll som kallas MSP utvecklats för kommunikation mellan satellitens huvuddator och experimenten. I detta arbete har MSP protokollet implementerats för experimenten SiC och Piezo-LEGS Eftersom Piezo-LEGS experimentet är inte kompatibel med I2C bussen som används av MSP protokollet, utan istället använder sig utav ASCII-kommandon via RS-485, måste MSP kommandona översättas till ASCII-kommandon utav SiC.