Aaltodoc Repository :: Browsing by Author "Kallio, Esa"

Browsing by Author "Kallio, Esa"

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Advancing Our Understanding of Martian Proton Aurora Through a Coordinated Multi-Model Comparison Campaign
(Wiley-Blackwell, 2023-10) Hughes, Andréa C.G.; Chaffin, Michael; Mierkiewicz, Edwin; Deighan, Justin; Jolitz, Rebecca D.; Kallio, Esa; Gronoff, Guillaume; Shematovich, Valery; Bisikalo, Dmitry; Halekas, Jasper; Simon Wedlund, Cyril; Schneider, Nicholas; Ritter, Birgit; Girazian, Zachary; Jain, Sonal; Gérard, Jean Claude; Hegyi, Bradley; Department of Electronics and Nanoengineering; Esa Kallio Group; NASA Goddard Space Flight Center; University of Colorado Boulder; Embry-Riddle Aeronautical University; NASA Langley Research Center; Institute of Applied Astronomy of the Russian Academy of Sciences; University of Iowa; Royal Observatory of Belgium; Austrian Academy of Sciences
Proton aurora are the most commonly observed yet least studied type of aurora at Mars. In order to better understand the physics and driving processes of Martian proton aurora, we undertake a multi-model comparison campaign. We compare results from four different proton/hydrogen precipitation models with unique abilities to represent Martian proton aurora: Jolitz model (3-D Monte Carlo), Kallio model (3-D Monte Carlo), Bisikalo/Shematovich et al. model (1-D kinetic Monte Carlo), and Gronoff et al. model (1-D kinetic). This campaign is divided into two steps: an inter-model comparison and a data-model comparison. The inter-model comparison entails modeling five different representative cases using similar constraints in order to better understand the capabilities and limitations of each of the models. Through this step we find that the two primary variables affecting proton aurora are the incident solar wind particle flux and velocity. In the data-model comparison, we assess the robustness of each model based on its ability to reproduce a proton aurora observation. All models are able to effectively simulate the general shape of the data. Variations in modeled intensity and peak altitude can be attributed to differences in model capabilities/solving techniques and input assumptions (e.g., cross sections, 3-D vs. 1-D solvers, and implementation of the relevant physics and processes). The good match between the observations and multiple models gives a measure of confidence that the appropriate physical processes and their associated parameters have been correctly identified and provides insight into the key physics that should be incorporated in future models.
Aurinkokunnan kappaleiden lähiavaruuden mallinnus tietokonesimulaatiolla: Aalto-yliopiston avaruussääsimulaatio
(2020-05-24) Ihalainen, Jimmy; Kallio, Esa; Sähkötekniikan korkeakoulu; Turunen, Markus
Auroral Imaging With Combined Suomi 100 Nanosatellite and Ground-Based Observations: A Case Study
(Wiley-Blackwell, 2023-05) Kallio, Esa; Harri, Ari Matti; Knuuttila, Olli; Jarvinen, Riku; Kauristie, Kirsti; Kestilä, Antti; Kivekäs, Jarmo; Koskimaa, Petri; Lukkari, Juha Matti; Partamies, Noora; Rynö, Jouni; Syrjäsuo, Mikko; Department of Electronics and Nanoengineering; Finnish Meteorological Institute; Esa Kallio Group; University Centre in Svalbard; Department of Electronics and Nanoengineering
Auroras can be regarded as the most fascinating manifestation of space weather and they are continuously observed by ground-based and, nowadays more and more, also by space-based measurements. Investigations of auroras and geospace comprise the main research goals of the Suomi 100 nanosatellite, the first Finnish space research satellite, which has been measuring the Earth's ionosphere since its launch on 3 December 2018. In this work, we present a case study where the satellite's camera observations of an aurora over Northern Europe are combined with ground-based observations of the same event. The analyzed image is, to the authors' best knowledge, the first auroral image ever taken by a CubeSat. Our data analysis shows that a satellite vantage point provides complementary, novel information of such phenomena. The 3D auroral location reconstruction of the analyzed auroral event demonstrates how information from a 2D image can be used to provide location information of auroras under study. The location modeling also suggests that the Earth's limb direction, which was the case in the analyzed image, is an ideal direction to observe faint auroras. Although imaging on a small satellite has some large disadvantages compared with ground-based imaging (the camera cannot be repaired, a fast moving spinning satellite), the data analysis and modeling demonstrate how even a small 1-Unit (size: 10 × 10 × 10 cm) CubeSat and its camera, build using cheap commercial off-the-shelf components, can open new possibilities for auroral research, especially, when its measurements are combined with ground-based observations.
Automated functional system integration testing of Suomi 100 satellite
(2018-06-18) Lukkari, Juha; Kestilä, Antti; Sähkötekniikan korkeakoulu; Kallio, Esa
A large portion of launched CubeSats have failed early on their missions. Potential source of failures has been identified from statistical data of CubeSat missions as being inadequate functional system integration testing. In this thesis test automation was used to perform functional system integration testing for the Suomi 100 CubeSat. Reusable software library, called CubeSatAutomation, was developed for test automation and testing was conducted with a widely used open source test automation framework known as Robot Framework. With the performed tests proper functionality was verified for essential satellite features such as radio communication, telemetry, safe resets and battery recharging through the solar panels among others. The testing however identified certain issues in the integration of the payload radio instrument. The tests included the “Day in the life” testing and it is possible to anticipate that this test can increase the overall success rate of CubeSat missions. A testing guideline that includes this test is recommended to be added to the CubeSat project.
Automation of Operation and Testing for European Space Agency's OPS-SAT Mission
(2019-08-19) Hessinger, Felix; Evans, David; Sähkötekniikan korkeakoulu; Kallio, Esa
This thesis presents a solution for mission operation automation in European Space Agency's (ESA) OPS-SAT mission. To achieve this, the ESA internal mission automation system (MATIS) in combination with the mission control software (SCOS) are used. They control the satellite and all ground peripherals and programmes to enable fully automated and unsupervised satellite passes. The goal of this work is the transition from the existing manual operation, with a human operator watching over and controlling all systems, to an automated system. This system supports the operation engineer and replaces the operator himself. A large section of this thesis consists of the setup, configuration, integration of all programmes and virtual machines and testing of the MATIS software, as well as the Service Management Framework (SMF) which connects MATIS to non-MATIS applications like SCOS. During testing, a lot of problems could be identified, not only OPS-SAT specific ones, but also general problems applying to all missions that consider using MATIS for future operation automation. These findings and bugs discovered during testing are reported to the responsible authorities and presented in this work. Further features of this thesis are the elaborations of the mission operation automation concept and the satellite pass concept, providing an in-depth view of the automation and passes of OPS-SAT as well as the general concepts and thoughts, which can be used by other missions to accelerate integration. An additional key feature of this thesis is the newly developed standard for operation notation in Excel, which has been achieved in close cooperation with the operation engineer. Furthermore, to accelerate the process of switching from manual to automated procedures, several converters have been developed iteratively with the new standard. These converters allow fast transformation from Excel to the procedure programming language called PLUTO used by MATIS. Not only do the results and converters of this work accelerate the procedure integration by 80%, they also deliver a more stable mission automation system that can be used by other missions as well. Operation automation reduces the operational costs for satellites and space missions significantly, as well as reducing the human error to a minimum. Therefore, this thesis is the first step towards a future with complete automation in the area of satellite operations. Without this automation, future satellite cluster configurations, like Starlink from SpaceX, will not be possible to put into practice, due to their high complexity, exceeding the comprehensibility and reaction time of humans.
BepiColombo ja Merkuriuksen avaruussää
(2021-05-04) Van Der Knaap, Alpo; Kallio, Esa; Sähkötekniikan korkeakoulu; Turunen, Markus
The BepiColombo Mercury Imaging X-Ray Spectrometer: Science Goals, Instrument Performance and Operations
(SPRINGER, 2020-11-03) Bunce, Emma J.; Martindale, Adrian; Lindsay, Simon; Muinonen, Karri; Rothery, David A.; Pearson, Jim; McDonnell, Ivor; Thomas, Chris; Thornhill, Julian; Tikkanen, Tuomo; Feldman, Charly; Huovelin, Juhani; Korpela, Seppo; Esko, Eero; Lehtolainen, Arto; Treis, Johannes; Majewski, Petra; Hilchenbach, Martin; Väisänen, Timo; Luttinen, Arto; Kohout, Tomas; Penttilä, Antti; Bridges, John; Joy, Katherine H.; Alcacera-Gil, Maria Angeles; Alibert, Guilhem; Anand, Mahesh; Bannister, Nigel; Barcelo-Garcia, Corinne; Bicknell, Chris; Blake, Oliver; Bland, Phil; Butcher, Gillian; Cheney, Andy; Christensen, Ulrich; Crawford, Tony; Crawford, Ian A.; Dennerl, Konrad; Dougherty, Michele; Drumm, Paul; Fairbend, Raymond; Genzer, Maria; Grande, Manuel; Hall, Graeme P.; Hodnett, Rosie; Houghton, Paul; Imber, Suzanne; Kallio, Esa; Lara, Maria Luisa; Balado Margeli, Ana; Mas-Hesse, Miguel J.; Maurice, Sylvestre; Milan, Steve; Millington-Hotze, Peter; Nenonen, Seppo; Nittler, Larry; Okada, Tatsuaki; Ormö, Jens; Perez-Mercader, Juan; Poyner, Richard; Robert, Eddy; Ross, Duncan; Pajas-Sanz, Miriam; Schyns, Emile; Seguy, Julien; Strüder, Lothar; Vaudon, Nathalie; Viceira-Martín, Jose; Williams, Hugo; Willingale, Dick; Yeoman, Tim; Department of Electronics and Nanoengineering; Esa Kallio Group; University of Leicester; University of Helsinki; Open University Milton Keynes; Max Planck Institute Semiconductor Laboratory; PNSensor GmbH; Max Planck Institute for Solar System Research; University of Manchester; Instituto Nacional de Técnica Aeroespacial Esteban Terradas; Photonis; Curtin University; Birkbeck University of London; Max Planck Institute for Extraterrestrial Physics; Imperial College London; Finnish Meteorological Institute; Aberystwyth University; CSIC; Oxford Instruments Analytical Oy; Carnegie Institution of Washington; Institute of Space and Astronautical Science; Harvard University
The Mercury Imaging X-ray Spectrometer is a highly novel instrument that is designed to map Mercury’s elemental composition from orbit at two angular resolutions. By observing the fluorescence X-rays generated when solar-coronal X-rays and charged particles interact with the surface regolith, MIXS will be able to measure the atomic composition of the upper ∼10-20 μm of Mercury’s surface on the day-side. Through precipitating particles on the night-side, MIXS will also determine the dynamic interaction of the planet’s surface with the surrounding space environment. MIXS is composed of two complementary elements: MIXS-C is a collimated instrument which will achieve global coverage at a similar spatial resolution to that achieved (in the northern hemisphere only – i.e. ∼ 50 – 100 km) by MESSENGER; MIXS-T is the first ever X-ray telescope to be sent to another planet and will, during periods of high solar activity (or intense precipitation of charged particles), reveal the X-ray flux from Mercury at better than 10 km resolution. The design, performance, scientific goals and operations plans of the instrument are discussed, including the initial results from commissioning in space.
CNN-based local features for navigation near an asteroid
(IEEE, 2024) Knuuttila, Olli; Kestila, Antti; Kallio, Esa; Department of Electronics and Nanoengineering; Esa Kallio Group
This article addresses the challenge of vision-based proximity navigation in asteroid exploration missions and on-orbit servicing. Traditional feature extraction methods struggle with the significant appearance variations of asteroids due to limited scattered light. To overcome this, we propose a lightweight feature extractor specifically tailored for asteroid proximity navigation, designed to be robust to illumination changes and affine transformations. We compare and evaluate state-of-the-art feature extraction networks and three lightweight network architectures in the asteroid context. Our proposed feature extractors and their evaluation leverage synthetic images and real-world data from missions such as NEAR Shoemaker, Hayabusa, Rosetta, and OSIRIS-REx. Our contributions include a trained feature extractor, incremental improvements over existing methods, and a pipeline for training domain-specific feature extractors. Experimental results demonstrate the effectiveness of our approach in achieving accurate navigation and localization. This work aims to advance the field of asteroid navigation and provides insights for future research in this domain.
Cometary Ion Dynamics with Rosetta Ion Composition Analyzer
(2019-10-21) Gupta, Shashikant; Järvinen, Riku; Sähkötekniikan korkeakoulu; Kallio, Esa
For centuries, comet sightings have fascinated us and we have strived to understand their nature. The knowledge of the behavior and composition of comets would help in understanding the formation of the Solar System, as they are believed to be the oldest objects in it. Cometary research, however, is in a developing stage because from an estimated trillion of comets, we have studied one through extended in-situ in-orbit measurements. Previous research has now established that comets become visible when they approach close to the Sun while their surface volatile material is sublimed by the solar radiation. The neutral atmosphere thus created is also ionized by the solar radiation, resulting in creation of positive cometary ions that are picked up and accelerated by the solar wind electric and magnetic fields. The fields influence the trajectories of these accelerated ions, causing variations in their flow angles as a function of their energy, a mechanism called energy - angle dispersion. Dispersion has only been studied for specific cases so far. In this work, the nature of the energy - angle dispersion is statistically examined using scientific data from the Rosetta mission, which orbited the Comet 67P/Churyumov-Gerasimenko from August 2014 to September 2016. One of the instruments onboard Rosetta, the Ion Composition Analyzer (ICA), measured the three-dimensional 360◦ × 90◦ energy and mass distribution of positive ions around the comet. In this work, the ICA data is used to identify dispersion events, their properties and trends using data analysis and image processing techniques at different temporal resolutions. The results are analyzed against the data from physical simulations, models and instruments onboard Rosetta. With the detailed statistical and quantitative analysis of the evolution of the energy - angle dispersion, it is found that the dispersion events are quite coherent over time scales of a few days and that the dispersion is very dynamic in nature. An understanding of this dispersion of accelerated cometary ions is key to understand the cometary ion dynamics.
Constructing Spacecraft Components Using Additive Manufacturing and Atomic Layer Deposition: First Steps for Integrated Electric Circuitry
(AMERICAN SOCIETY OF CIVIL ENGINEERS, 2021-09-01) Nyman, Leo; Kestilä, Antti; Porri, Paavo; Pudas, Marko; Salmi, Mika; Silander, Rudolf; Miikkulainen, Ville; Kaipio, Mikko; Kallio, Esa; Ritala, Mikko; Department of Electronics and Nanoengineering; Department of Mechanical Engineering; Department of Chemistry and Materials Science; Esa Kallio Group; Advanced Manufacturing and Materials; VTT Technical Research Centre of Finland; Picosun Oy; Department of Electronics and Nanoengineering; University of Helsinki; Finnish Meteorological Institute
Many fields, including the aerospace industry, have shown increased interest in the use of plastics to lower the mass of systems. However, the use of plastics in space can be challenging for a number of reasons. Ultraviolet radiation, atomic oxygen, and other phenomena specifically associated with space cause the degradation of polymers. Here we show a path toward creation of space-grade components by combining additive manufacturing (AM) and atomic layer deposition (ALD). Our method produced ALD Al2O3 coated thermoplastic parts suitable for space applications. The highlight of this work is a significant reduction in outgassing, demonstrated using residual gas analyzer (RGA) sampling. Compared to uncoated parts, the ALD Al2O3 coating decreased the outgassing of polyether ether ketone (PEEK), acrylonitrile butadiene styrene (ABS), polycarbonate (PC), and nanodiamond-doped polylactide (ND-PLA) by 46%, 49%, 58%, and 65%, respectively. The manufacturing method used in this work enables the use of topology optimization already in the early concept creation phase. The method is ideally suited for spacecraft applications, in which the volume and mass of parts is critical, and could also be adapted for in-space manufacturing.
Dayside Transient Phenomena and Their Impact on the Magnetosphere and Ionosphere
(SPRINGER, 2022-08) Zhang, Hui; Zong, Qiugang; Connor, Hyunju; Delamere, Peter; Facskó, Gábor; Han, Desheng; Hasegawa, Hiroshi; Kallio, Esa; Kis, Árpád; Le, Guan; Lembège, Bertrand; Lin, Yu; Liu, Terry; Oksavik, Kjellmar; Omidi, Nojan; Otto, Antonius; Ren, Jie; Shi, Quanqi; Sibeck, David; Yao, Shutao; Department of Electronics and Nanoengineering; Esa Kallio Group; University of Alaska Fairbanks; Peking University; Wigner Research Centre for Physics; Tongji University; Institute of Space and Astronautical Science; Institute of Earth Physics and Space Science; NASA Goddard Space Flight Center; Laboratoire Atmosphères; Auburn University; University of Bergen; Solana Scientic Inc.; Shandong University
Dayside transients, such as hot flow anomalies, foreshock bubbles, magnetosheath jets, flux transfer events, and surface waves, are frequently observed upstream from the bow shock, in the magnetosheath, and at the magnetopause. They play a significant role in the solar wind-magnetosphere-ionosphere coupling. Foreshock transient phenomena, associated with variations in the solar wind dynamic pressure, deform the magnetopause, and in turn generates field-aligned currents (FACs) connected to the auroral ionosphere. Solar wind dynamic pressure variations and transient phenomena at the dayside magnetopause drive magnetospheric ultra low frequency (ULF) waves, which can play an important role in the dynamics of Earth’s radiation belts. These transient phenomena and their geoeffects have been investigated using coordinated in-situ spacecraft observations, spacecraft-borne imagers, ground-based observations, and numerical simulations. Cluster, THEMIS, Geotail, and MMS multi-mission observations allow us to track the motion and time evolution of transient phenomena at different spatial and temporal scales in detail, whereas ground-based experiments can observe the ionospheric projections of transient magnetopause phenomena such as waves on the magnetopause driven by hot flow anomalies or flux transfer events produced by bursty reconnection across their full longitudinal and latitudinal extent. Magnetohydrodynamics (MHD), hybrid, and particle-in-cell (PIC) simulations are powerful tools to simulate the dayside transient phenomena. This paper provides a comprehensive review of the present understanding of dayside transient phenomena at Earth and other planets, their geoeffects, and outstanding questions.
Design and Testing of Antenna Deployment System for Aalto-1 Satellite
(2015-12-14) Lankinen, Mikko; Jaan, Praks; Sähkötekniikan korkeakoulu; Kallio, Esa
Aalto-1 is a nanosatellite based on CubeSat standard which will be launched in 2016. For command link and telemetry, Aalto-1 uses a UHF radio system operating at a 437.22 MHz frequency. For transmitting data to Earth, the UHF radio system requires antennas as well as an antenna deployment system (ADS), which would enable the antennas to be opened in operational configuration after the launch. The ADS compactly stores antennas into a small space before launch and then deploys them once the satellite is in orbit. This thesis designs, constructs and tests an ADS for the Aalto-1 satellite. The thesis focuses on three areas of the ADS design: mechanical design, electrical design and radio frequency (RF) design. The mechanical design includes selection of antenna stowage configuration, ADS location on the satellite and an antenna release mechanism. Electrical design includes a trade-off between various solutions for implementing the required ADS timer, design of the circuit schematic for the ADS timer, design of the Printed Circuit Board (PCB) for the ADS timer, and electronic component selection. RF design includes modelling the satellite structure, ADS and antennas using 3D electromagnetic simulation software. Antenna performance was optimized to meet mission requirements. To verify the simulation results, antennas were measured in an anechoic chamber. Moreover, ADS was subjected to a series of tests: vibration testing, thermal cycling testing and communication range testing. Thorough testing has not only ensured that ADS can withstand launch conditions and the space environment but will also work according to specifications.
Design of a software defined radio spectrometer for space applications
(2023-01-23) Peltola, Tatu; Kallio, Esa; Sähkötekniikan korkeakoulu; Wichman, Risto
This thesis presents a system for measurements of high frequency (HF, 3-30 MHz) radio waves using a direct sampling receiver. Signal processing software developed in the work allows simultaneous spectrum analysis and reception of multiple narrow band channels on any frequencies within the HF range. The software makes use of parallel computing on general purpose multi-core processors. A fast-convolution filter bank is used for computationally efficient down-conversion of radio channels. Measurement setup built in the work consists of an antenna, an RX888 direct sampling receiver and a computer. The setup was successfully used to measure HF spectrum for 14 months.
The development of a Hardware-in-the-Loop test setup for event-based vision near-space space objects
(2023-06-12) van den Boogaard, Rik Gerardus; Knuuttila, Olli; Sähkötekniikan korkeakoulu; Kallio, Esa
The purpose of this thesis work was to develop a Hardware-in-the-Loop imaging setup that enables experimenting with an event-based and frame-based camera under simulated space conditions. The generated data sets were used to compare visual navigation algorithms in terms of an event-based and frame-based feature detection and tracking algorithm. The comparative analyses of the feature detection and tracking algorithms were used to get insights into the feasibility of event-based vision near-space space objects. Event-based cameras differ from frame-based cameras by how they produce an asynchronous and independent stream of events caused by brightness changes at each pixel instead of capturing images at a fixed rate. The setup design is based on a theoretical framework incorporating optical calculations. These calculations indicating the asteroid model needed to be scaled down by a factor of 3192 to fit inside the camera depth-of-view. This resulted in a scaled Bennu asteroid with a size of 16.44 centimeters. The cameras under testing conducted three experiments to generate data sets. The utilization of a feature detection and tracking algorithm on both camera data sets revealed that the absolute number of tracked features, computation time, and robustness in various scenarios of the frame-based camera algorithm outperforms the event-based camera algorithm. However, when considering the percentages of tracked features relative to the total detected features, the event-based algorithm tracks a significantly higher percentage of features for at least one key frame than the frame-based algorithm. The comparative analysis of the experiments performed in space-simulated conditions during this project showed that the feasibility of an event-based camera using solely events is low compared to the frame-based camera.
Development of the Aalto Virtual Planetarium for space science and applications
(2023-10-09) Helander, Henry; Kallio, Esa; Järvinen, Riku; Sähkötekniikan korkeakoulu; Kallio, Esa
The thesis describes the development process of the Aalto Virtual Planetarium software. It introduces the topic by first discussing the basic space physic concepts related to space plasma environment. Four different types of interaction are discussed: Earth-like, Venus-like, comet-like and Moon-like interaction. After this, the concept of plasma modelling is explained. The three most common plasma models: the full kinetic, the magnetohydrodynamic and the hybrid model are each briefly described. Next, the hybrid model developed by the Finnish Meteorological Institute and the Aalto University is introduced along with the related equations. After these basic plasma modelling concepts, virtual reality and related simulation and coding tools are discussed. Following this, the Aalto Virtual Planetarium software is introduced as well as the basic astronomical principles used for calculating the orbital locations of the planets. After this, the new features added to the Aalto Virtual Planetarium are discussed in detail. They include the trajectories of BepiColombo and JUICE spacecraft, interplanetary magnetic field (IMF), the Moon of Earth, hand-menu additions, start-screen improvements, 3D models of spacecraft, background stars and the Galilean moons of the planet Jupiter: Io, Europa, Ganymede and Callisto. Implementation and testing of these newly added major and minor software features during the thesis are then described. This is followed by a discussion of the software versions for other platforms. Specific changes made to the Windows version of the Aalto Virtual Planetarium are listed, and the Linux and ThingLink software versions are also briefly introduced. Finally, suggestions are made regarding possible future improvements that could be made to the software tool. For example, additional platforms and new features are suggested.
Energization of planetary pickup ions in the solar system
(2014) Jarvinen, Riku; Kallio, Esa; Esa Kallio Group; Department of Radio Science and Engineering
Eurotalletuksiin liittyvät riskit
(1986) Kallio, Esa; Niskakangas, Pekka; HKKK. Lask. Pro gradu; Kauppakorkeakoulu; School of Business
A feasibility study on ground-based localization for Mars exploration
(2015-08-24) van Gijlswijk, Rian; Vanhamäki, Heikki; Sähkötekniikan korkeakoulu; Kallio, Esa
The goal of this work is to assert the feasibility of the use of a ground-based network, consisting of beacons, to aid in the provision of localization for mobile stations on Mars. The dayside ionosphere can be utilized to refract and reflect radio signals to some receiver beyond the horizon. The propagation of radio signals is studied with the use of a simulation, which makes use of a ray-tracing method to track radio signals in the ionosphere. Several scenarios are defined to classify the state of the ionosphere. A nominal scenario is provided, with ionospheric properties prevalent at Mars. Furthermore, scenarios are defined to include both a minimum and maximum solar activity, as well as dust storms and SEP events. The determination of the position of a mobile station can be done by exploiting the properties of the received signal. Three localization technologies are studied in detail in this work, being the time of arrival ( TOA ), received signal strength ( RSS ) and angle of arrival ( AoA ). The Cramer-Rao lower bound ( CRLB ) is used to determine the lower bound of the precision of a position estimate, produced by any of these technologies. A comparison of the obtained precisions shows that it is possible to obtain a precision of less than 13m for any scenario when using TOA technology, and 6m when using AoA technology. Furthermore, a coverage of at least 92 % is achieved in all but the most extreme scenarios. The coverage increases with decreasing frequency. The best results are obtained with a frequency of 2:5MHz. Moreover, it is shown that the best precision is obtained by placing beacons either in a rectangular or triangular grid on Mars, with beacons spaced 10_ apart. By doing so, a 4m precision can even be obtained under the nominal scenario for a frequency of 2:5MHz and 4:5MHz with any technology. Ultimately, a ground-based beacon system has proven to be a sound solution to providing positioning estimates on the Martian surface.
Ferrite Rod Antenna in a Nanosatellite Medium and High Frequency Radio
(2016-10-31) Koskimaa, Petri; Mallat, Juha; Kestilä, Antti; Sähkötekniikan korkeakoulu; Kallio, Esa
In this thesis the feasibility of using a ferrite rod antenna as a part of a radio instrument in a nanosatellite was studied. Ferrite rod antennas are used as receiving antennas for amplitude modulation transmissions in the medium and high frequencies. At these frequencies it is possible to study ionospheric properties due to the refraction of radiowaves from different ionospheric layers. The behavior of the antenna was determined from theory and tested using electromagnetic simulation software and measurements. The aluminum body and other metallic structures in the satellite affect the operation of the antenna and its position must be chosen carefully. The results show that ferrite rod antennas can be used for the purpose of receiving medium and high frequency transmissions in an aluminum framed nanosatellite.
Forcing continuous reconnection in hybrid simulations
(2014) Laitinen, Tiera; Jarvinen, Riku; Kallio, Esa; Janhunen, Pekka; Esa Kallio Group; Department of Radio Science and Engineering

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