Dissertations / Theses on the topic 'Astrodynamics and space situational awareness'
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Nastasi, Kevin Michael. "Autonomous and Responsive Surveillance Network Management for Adaptive Space Situational Awareness." Diss., Virginia Tech, 2018. http://hdl.handle.net/10919/84931.
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As resident space object populations grow, and satellite propulsion capabilities improve, it will become increasingly challenging for space-reliant nations to maintain space situational awareness using current human-in-the-loop methods. This dissertation develops several real-time adaptive approaches to autonomous sensor network management for tracking multiple maneuvering and non-maneuvering satellites with a diversely populated Space Object Surveillance and Identification network. The proposed methods integrate suboptimal Partially Observed Markov Decision Processes (POMDPs) with covariance inflation or multiple model adaptive estimation techniques to task sensors and maintain viable orbit estimates for all targets. The POMDPs developed in this dissertation use information-based and system-based metrics to determine the rewards and costs associated with tasking a specific sensor to track a particular satellite. Like in real-world situations, the population of target satellites vastly outnumbers the available set of sensors. Robust and adaptable tasking algorithms are needed in this scenario to determine how and when sensors should be tasked. The strategies developed in this dissertation successfully track 207 non-maneuvering and maneuvering spacecraft using only 24 ground and space-based sensors. The results show that multiple model adaptive estimation coupled with a multi-metric, suboptimal POMDP can effectively and efficiently task a diverse network of sensors to track multiple maneuvering spacecraft, while simultaneously monitoring a large number of non-maneuvering objects. Overall, this dissertation demonstrates the potential for autonomous and adaptable sensor network command and control for real-world space situational awareness.Ph. D.
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Gast, David W. "LIDAR design for space situational awareness." Thesis, Monterey, Calif. : Naval Postgraduate School, 2008. http://edocs.nps.edu/npspubs/scholarly/theses/2008/Sept/08Sep%5FGast.pdf.
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Thesis (M.S. in Astronautical Engineering)--Naval Postgraduate School, September 2008.Thesis Advisor(s): Agrawal, Brij N. ; Boger, Dan C. "September 2008." Description based on title screen as viewed on November 3, 2008. Includes bibliographical references (p. 79-80). Also available in print.
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O'Brien, Tolulope E. "Space situational awareness CubeSat concept of operations." Monterey, California. Naval Postgraduate School, 2011. http://hdl.handle.net/10945/10664.
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The concept of space situational awareness (SSA) is important to preserve manned and unmanned space operations. Traditionally, ground based radar, electro-optical sensors and very limited space-based assets have been used as part of the space surveillance network (SSN) to track orbital debris, inactive and active satellites alike. With the current SSN assets aging and the need for SSA growing, it is important to explore new ways to ensure proper SSA is maintained to preserve space operations. The Space-based Telescope for the Actionable Refinement of Ephemeris (STARE) project was initiated to explore the potential for a cube satellite (CubeSat) to contribute to the current SSN, with an optical payload integrated into a 3U Colony II Bus. The bus and payload data from the CubeSat will be collected by the Naval Postgraduate School Mobile CubeSat Command and Control ground station. Telemetry data from the bus will be analyzed at NPS and the payload data at Lawrence Livermore National Laboratory. This thesis outlines the concept of operation for the STARE CubeSat and investigates the possibility of using the data generated by STARE to augment the SSN to reduce the errors associated with conjunction analysis performed at the Joint Space Operations Center.
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Gondelach, David J. "Orbit prediction and analysis for space situational awareness." Thesis, University of Surrey, 2019. http://epubs.surrey.ac.uk/850116/.
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The continuation of space activities is at risk due to the growing number of uncontrolled objects, called space debris, which can collide with operational spacecraft. In addition, debris can fall back to the Earth causing risks to the population. Therefore, space agencies have started space situational awareness (SSA) programs and taken space debris mitigation measures to reduce the risks caused by uncontrolled objects and prevent the generation of new debris. A fundamental need for SSA is the capability to predict, design and analyse orbits. In this work, new techniques for orbit prediction are developed that are suitable for SSA in terms of accuracy, efficiency and ability to deal with uncertainties and are applied for re-entry prediction, end-of-life disposal, ADR mission design and long-term orbit prediction. The performance of high-order Poincaré mapping of perturbed orbits is improved by introducing a new set of orbital elements and the method is applied for orbit propagation and analysis of quasi-periodic orbits. Two new Lambert problem solvers are developed to compute perturbed rendezvous trajectories with hundreds of revolutions for the design of active debris removal missions. The computation of the effect of drag for semi-analytical propagation is speed up by using high-order Taylor expansions to evaluate the mean element rates efficiently. In addition, the high-order expansion of the flow through semi-analytical propagation is enabled using differential algebra to allow efficient propagation of initial conditions. The predictability of Galileo disposal orbits was investigated using chaos indicators and sensitivity analysis. The study showed that the orbits are predictable and that chaos indicators are not unsuitable for predictability analysis. Finally, to improve the re-entry prediction of rocket bodies based on two-line element data, ballistic coefficient and state estimation methods are enhanced. Using the developed approach, the re-entry prediction using only a ballistic coefficient estimate was found to be as accurate as re-entry prediction after full state estimation.
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Alinder, Simon. "Space Situational Awareness with the Swedish Allsky Meteor Network." Thesis, Uppsala universitet, Observationell astrofysik, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-390397.
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This thesis investigates the use of the Swedish Allsky Meteor Network (SAMN) for observing, identifying, and determining the orbits of satellites. The overall goal of this project is to determine the feasibility of using such a network for Space Situational Awareness (SSA) purposes, which requires identification and monitoring of objects in orbit. This thesis is a collaboration with the Swedish Defense Research Agency (FOI) to support their efforts in SSA. Within the frame of this project, the author developed software that can take data of observations of an object collected from the all-sky cameras of SAMN and do an Initial Orbit Determination (IOD) of the object. An algorithm that improves the results of the IOD was developed and integrated into the software. The software can also identify the object if it is in a database that the program has access to or, if it could not be identified, make an approximate prediction of when and where the object will be visible again the next time it flies over. A program that analyses the stability of the results of the IOD was also developed. This measures the spread in results of the IOD when a small amount of artificial noise is added to one or more of the observed coordinates in the sky. It was found that using multiple cameras at different locations greatly improves the stability of the solutions. Gauss' method was used for doing the IODs. The advantages and disadvantages of using this method are discussed, and ultimately other methods, such as the Gooding method or Double R iteration, are recommended for future works. This is mostly because Gauss' method has a singularity when all three lines of sight from observer to object lie in the same plane, which makes the results unreliable. The software was tested on a number of observations, both synthetic and real, and the results were compared against known data from public databases. It was found that these techniques can, with some changes, be used for doing IOD and satellite identification, but that doing very accurate position determination required for full orbit determination is not feasible.Detta examensarbete undersöker möjligheterna att använda ett svenskt nätverk av allskykameror kallat SAMN (Swedish Allsky Meteor Network) för att observera, identifiera och banbestämma satelliter. Det övergripande målet med detta projekt är att bestämma hur användbart ett sådant nätverk skulle vara för att skapa en rymdlägesbild, vilken i sin tur kräver bevakning och identifikation av objekt som ligger i omloppsbana. Detta examensarbete är ett samarbete mellan Uppsala Universitet och FOI (Totalförsvarets Forskningsinstitut). Inom ramen för detta projekt har författaren utvecklat mjukvara som kan ta data från observationer av objekt utförda av SAMN och göra initiala banbestämningar av objekten. En algoritm som förbättrar resultaten av den initiala banbestämningen utvecklades och integrerades i programmen. Programmen kan också identifiera satelliter om de finns med i en databas som programmet har tillgång till eller förutsäga objektets nästa passage över observatören om det inte kunde identifieras. Ett annat program som analyserar känsligheten av resultaten av den initiala banbestämningen utvecklades också. Detta program mäter spridningen i resultat som orsakas av små störningar i de observerade koordinaterna på himlen. Det framkom att stabiliteten av resultaten kan förbättras avsevärt genom att använda flera observatörer på olika orter. I detta projekt användes Gauss metod för att göra banbestämningarna. Metodens för- och nackdelar diskuteras och i slutänden rekommenderas istället andra metoder, som Goodings metod eller Dubbel R-iteration, för framtida arbeten. Detta beror mest på att Gauss metod innehåller en singularitet när alla siktlinjer från observatören till objektet ligger i samma plan som varandra vilket gör resultaten opålitliga i de fallen. Programmen testkördes på ett antal olika observationer, både artificiella och verkliga, och resultaten jämfördes med kända positioner. Slutsatsen av arbetet är att de undersökta teknikerna kan, med vissa modifikationer, användas för att göra initiala banbestämningar och satellitidentifikationer, men att göra de väldigt precisa positionsbestämningarna som krävs för fullständig banbestämning är inte genomförbart.
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Flanagan, Jason A. "Enhancing space situational awareness using a 3U CubeSat with optical imager." Thesis, Monterey, California. Naval Postgraduate School, 2010. http://hdl.handle.net/10945/5001.
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Approved for public release; distribution is unlimitedSpace situational awareness is extremely important in order to maintain the safety and usability of earth-orbiting satellites, as well as protecting astronauts living and working in space. Traditional space situational awareness is achieved using ground-based radar and optical sensors. This thesis explores the feasibility of space-based space situational awareness using a 3U CubeSat with an optical imager to augment the Space Surveillance Network by capturing conjunctions in space, from which ephemeris data of earth orbiting objects can be updated to more accurately predict future orbital positions. Work completed includes preliminary work towards building, testing, and using a Colony II Bus emulator and interface mechanism, allowing smooth payload and bus integration. Analysis of orbital trajectories for a reference orbit and potential crossing satellites provides insight into the capabilities of the SSA CubeSat. Future work is discussed.
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Zaman, Farakh B. "Building a local Space Situational Awareness (SSA) architecture using hosted payloads." Thesis, Monterey California. Naval Postgraduate School, 2013. http://hdl.handle.net/10945/37749.
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Approved for public release; distribution is unlimitedFrom a military standpoint, space-based capabilities and the need to know what is happening in space, or Space Situational Awareness (SSA), have become invaluable. Current SSA capabilities are expensive and are limited in scope. Hosted payloads however, provide a unique method to provide SSA in a relatively inexpensive manner. This thesis explores the development of an architecture for SSA using hosted payloads. For this thesis, research was conducted on existing systems. NASA and Air Force programs were reviewed to gain an understanding of hosted payloads, and a set of generic high-level requirements were developed for a hosted payload. These requirements will meet the needs of a hosted SSA payload that can enable a larger SSA architecture using hosted payloads. Once the requirements were developed, modeling and simulation using Satellite Tool Kit (STK) was were employed to develop an optimal SSA system using hosted payloads. Finally, once the architecture was defined, an Operational View 1 (OV-1) was developed to provide a graphical representation of the architecture.
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Persico, Adriano Rosario. "Advanced signal processing tools for ballistic missile defence and space situational awareness." Thesis, University of Strathclyde, 2018. http://digitool.lib.strath.ac.uk:80/R/?func=dbin-jump-full&object_id=30190.
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The research presented in this Thesis deals with signal processing algorithms for the classification of sensitive targets for defence applications and with novel solutions for the detection of space objects. These novel tools include classification algorithms for Ballistic Targets (BTs) from both micro-Doppler (mD) and High Resolution Range Profiles (HRRPs) of a target, and a space-borne Passive Bistatic Radar (PBR) designed for exploiting the advantages guaranteed by the Forward Scattering (FS) configuration for the detection and identification of targets orbiting around the Earth. Nowadays the challenge of the identification of Ballistic Missile (BM) warheads in a cloud of decoys and debris is essential in order to optimize the use of ammunition resources. In this Thesis, two different and efficient robust frameworks are presented. Both the frameworks exploit in different fashions the effect in the radar return of micro-motions exhibited by the target during its flight. The first algorithm analyses the radar echo from the target in the time-frequency domain, with the aim to extract the mD information. Specifically, the Cadence Velocity Diagram (CVD) from the received signal is evaluated as mD profile of the target, where the mD components composing the radar echo and their repetition rates are shown. Different feature extraction approaches are proposed based on the estimation of statistical indices from the 1-Dimensional (1D) Averaged CVD (ACVD), on the evaluation of pseudo-Zerike (pZ) and Krawtchouk (Kr) image moments and on the use of 2-Dimensional (2D) Gabor filter, considering the CVD as 2D image. The reliability of the proposed feature extraction approaches is tested on both simulated and real data, demonstrating the adaptivity of the framework to different radar scenarios and to different amount of available resources. The real data are realized in laboratory, conducting an experiment for simulating the mD signature of a BT by using scaled replicas of the targets, a robotic manipulator for the micro-motions simulation and a Continuous Waveform (CW) radar for the radar measurements. The second algorithm is based on the computation of the Inverse Radon Transform (IRT) of the target signature, represented by a HRRP frame acquired within an entire period of the main rotating motion of the target, which are precession for warheads and tumbling for decoys. Following, pZ moments of the resulting transformation are evaluated as final feature vector for the classifier. The features guarantee robustness against the target dimensions and the initial phase and the angular velocity of its motion. The classification results on simulated data are shown for different polarization of the ElectroMagnetic (EM) radar waveform and for various operational conditions, confirming the the validity of the algorithm. The knowledge of space debris population is of fundamental importance for the safety of both the existing and new space missions. In this Thesis, a low budget solution to detect and possibly track space debris and satellites in Low Earth Orbit (LEO) is proposed. The concept consists in a space-borne PBR installed on a CubeSaT flying at low altitude and detecting the occultations of radio signals coming from existing satellites flying at higher altitudes. The feasibility of such a PBR system is conducted, with key performance such as metrics the minimumsize of detectable objects, taking into account visibility and frequency constraints on existing radio sources, the receiver size and the compatibility with current CubeSaT's technology. Different illuminator types and receiver altitudes are considered under the assumption that all illuminators and receivers are on circular orbits. Finally, the designed system can represent a possible solution to the the demand for Ballistic Missile Defence (BMD) systems able to provide early warning and classification and its potential has been assessed also for this purpose.
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Ohriner, Ethan Benjamin Lewis. "Investigation of Orbital Debris Situational Awareness with Constellation Design and Evaluation." Thesis, Virginia Tech, 2021. http://hdl.handle.net/10919/102096.
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Orbital debris is a current and growing threat to reliable space operations and new space vehicle traffic. As space traffic increases, so does the economic impact of orbital debris on the sustainability of systems that increasingly support national security and international commerce. Much of the debris collision risk is concentrated in specific high-density debris clusters in key regions of Low Earth Orbit (LEO). A potential long-term solution is to employ a constellation of observation satellites within these debris clusters to improve monitoring and characterization efforts, and engage in Laser Debris Removal (LDR) as means of collision mitigation. Here we adapted and improved a previous methodology for evaluating such designs. Further, we performed an analysis on the observer constellations' effectiveness over a range of circular, elliptical, and self-maneuvering designs. Our results show that increasingly complex designs result in improved performance of various criteria and that the proposed method of observation could significantly reduce the threat orbital debris poses to space operations and economic growth.Master of Science
Orbital debris is defined as all non-operational, man-made objects currently in space. US national space regulations require every new satellite to have a de-orbit plan to prevent the creation of new debris, but fails to address the thousands of derelict objects currently hindering space operations. As space traffic increases, so does the economic impact of orbital debris on the sustainability of systems that increasingly support national security and commercial growth. While orbital debris is usually assessed by looking at the full volume of space, most massive debris objects are concentrated in high-density clusters with a higher than normal probability for collision. A potential solution to the growing orbital debris problem is to place a group of observation satellites within these debris clusters to both improve monitoring capabilities and provide a means for preventing potential collisions by engaging with debris via Laser Debris Removal (LDR). This research presents a methodology for comparing and contrasting different observer satellite constellation designs. Our results show that increasingly complex orbit designs improve various performance criteria, but ultimately orbits that more closely match those of the debris objects provide the best coverage. The proposed method of observation and engagement could significantly reduce the threat orbital debris poses to space operations and economic growth.
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Sease, Bradley Jason. "Data Reduction for Diverse Optical Observers through Fundamental Dynamic and Geometric Analysis." Diss., Virginia Tech, 2016. http://hdl.handle.net/10919/70923.
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Typical algorithms for processing unresolved space imagery from optical systems make broad assumptions about the expected behavior of the sensors during collection. While these techniques are often successful at data reduction for a particular mission, they rarely extend to sensors in different operating modes. Such specialized techniques therefore reduce the number of sensors able to contribute imagery. By approaching this problem with analysis of the fundamental dynamic equations and geometry at play, we can gain a deeper understanding into the behavior of both stars and space objects viewed through optical sensors. This type of analysis has the potential to enable data collection from a wider variety of sensors, increasing both the quantity and quality of data available for space object catalog maintenance. This dissertation will explore the implications of this approach to unresolved data processing. Sensor-level motion descriptions will be derived and applied to the problem of space object discrimination and tracking. Results of this processing pipeline as applied to both simulated and real optical data will be presented.Ph. D.
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Bengtsson, Bernander Karl. "A Method for Detecting Resident Space Objects and Orbit Determination Based on Star Trackers and Image Analysis." Thesis, Uppsala universitet, Avdelningen för visuell information och interaktion, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-236873.
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Satellites commonly use onboard digital cameras, called star trackers. A star tracker determines the satellite's attitude, i.e. its orientation in space, by comparing star positions with databases of star patterns. In this thesis, I investigate the possibility of extending the functionality of star trackers to also detect the presence of resident space objects (RSO) orbiting the earth. RSO consist of both active satellites and orbital debris, such as inactive satellites, spent rocket stages and particles of different sizes. I implement and compare nine detection algorithms based on image analysis. The input is two hundred synthetic images, consisting of a portion of the night sky with added random Gaussian and banding noise. RSO, visible as faint lines in random positions, are added to half of the images. The algorithms are evaluated with respect to sensitivity (the true positive rate) and specificity (the true negative rate). Also, a difficulty metric encompassing execution times and computational complexity is used. The Laplacian of Gaussian algorithm outperforms the rest, with a sensitivity of 0.99, a specificity of 1 and a low difficulty. It is further tested to determine how its performance changes when varying parameters such as line length and noise strength. For high sensitivity, there is a lower limit in how faint the line can appear. Finally, I show that it is possible to use the extracted information to roughly estimate the orbit of the RSO. This can be accomplished using the Gaussian angles-only method. Three angular measurements of the RSO positions are needed, in addition to the times and the positions of the observer satellite. A computer architecture capable of image processing is needed for an onboard implementation of the method.
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Schwomeyer, Patrick. "The U.S. outer space situational awareness sharing law: sharing information about SSA and the need for global cooperation." Thesis, McGill University, 2011. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=104897.
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The world is quickly realizing how important space situational awareness (SSA) is to maintain the safety of all space faring entities. In order to achieve the safest environment possible, the sharing of information is critical. Without SSA data sharing, both nations and organizations are incapable of possessing absolute awareness of space and all the space objects orbiting therein. The field of SSA data sharing will be addressed in three parts. First, the technical background describing the outer space environment, orbital mechanics, SSA sensors and SSA data will be explored to provide a foundation for fully appreciating the legal strides needed in order to achieve greater international cooperation. Next, Section III will undertake an analysis of the law, policy and participants of SSA collection and dissemination within the United States by undertaking a review of 10 U.S.C. § 2274. The last part, Section IV, will broaden the investigation to include the other entire world players, including foreign governments, private enterprises and astronomers, as well as review several governance models which could provide potential governance structures for an international SSA data sharing network.Le monde réalise rapidement l'importance de la conscience en situation spatiale (SSA) puisqu'elle permet le maintien de la sécurité des Etats actifs en matière spatiale. Dans le but d'atteindre l'environnement le plus sécuritaire possible, le partage de l'information reste critique. En effet, sans partage de données SSA, nations et organisations sont incapables de posséder la connaissance absolue de l'espace et de tous les objets spatiaux en orbite qui s'y trouvent. Le partage de données SSA est abordé ici en trois parties. Tout d'abord, il s'agit d'explorer le contexte technique décrivant l'environnement de l'espace, de la mécanique orbitale, capteurs SSA et données SSA. Cette étude permet d'établir de solides bases pour apprécier pleinement les avancées juridiques nécessaires afin d'atteindre une plus grande coopération internationale. Ensuite, il s'agira d'analyser dans la Section III le système legislative ainsi que les politiques et les acteurs à la collecte de SSA et sa diffusion au sein des États-Unis. Cette dernière étude se fera par examen des 10 U.S.C. § 2274. La dernière partie, Section IV, va élargir l'enquête afin d'inclure d'autres acteurs, et ce, à échelle mondiale, incluant gouvernements étrangers, entreprises privées, astronomes, ainsi que plusieurs modèles de gouvernance susceptibles de constituer un corps de gouvernance potentiels gérant le partage des données internationales d‘un réseau SSA.
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Mukundan, Arvind. "Combined Heuristic and Statistical Methodologies applied to Maneuver Detection in the SST Observation Correlation Process." Thesis, Luleå tekniska universitet, Rymdteknik, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-81971.
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In this project, an algorithm has been proposed to detect a satellite’s maneuver by comparingthe orbital elements observed from the two line element data and the orbital elements propagatedwith the help of Simplified perturbations models. A set of TLE data for an object orbiting Earthcontains a specific set of orbital elements. Simplified perturbation are utilized to propagate theorbital velocity and position vector of the same object. By comparing the results obtained fromboth the methods, the maneuvers of a satellite are detected. This project outlines the workingmethodology and the implementation of the algorithm developed to detect the maneuvers. Thefunctioning of the technique is assessed with reference to two case studies for which the maneuverhistory is available by following the approach employed by Kelecy et al. (2007). The same methodis implemented to detect the orbit controlling maneuvers as well as the fine control maneuvers. Theresults derived from the analysis indicate that the maneuvers which has the magnitude of even aslow as cm/s has been detected when the detection parameters are calibrated properly.
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Ask, Jacob. "Selected Trends and Space Technologies Expected to Shape the Next Decade of SSC Services." Thesis, KTH, Rymdteknik, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-261779.
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Since the early 2000s the space industry has undergone significant changes such as the advent of reusable launch vehicles and an increase of commercial opportunities. This new space age is characterized by a dynamic entrepreneurial climate, lowered barriers to access space and the emergence of new markets. New business models are being developed by many actors and the merging of space and other sectors continues, facilitating innovative and disruptive opportunities. Already established companies are adapting in various ways as efforts to stay relevant are gaining attention. The previous pace of development that was exclusively determined by governmental programs are now largely set by private and commercial ventures. Relating to all trends, new technologies and driving forces in the space industry is no trivial matter. By analyzing and examining identified trends and technologies the author has attempted to discern those that will have a significant impact on the industrial environment during the next decade. Market assessments have been summarized and interviews have been carried out. Discussions and conclusions relating to the services provided by the Swedish Space Corporation are presented. This report is intended to update the reader on the current status of the space industry, introduce concepts and provide relevant commentary on many important trends.Sedan början av 2000-talet har det skett markanta förändringar inom rymdindustrin, såsom utvecklingen av återanvändningsbara raketer och en ökad mängd kommersiella möjligheter. Denna nya rymder a karaktäriseras av ett dynamiskt klimat för entreprenörer, minskande barriärer för att etablera rymdverksamhet och uppkomsten av nya marknader. Nya affärsmodeller utvecklas och integrering mellan rymden och andra industrier fortsätter, vilket ger utrymme för utveckling av innovativa och disruptiva idéer. Redan etablerade företag anpassar sig till förändringarna på olika sätt och ansträngningar för att bibehålla relevans prioriteras. Utvecklingstakten inom branschen var tidigare dominerad av statliga program men är nu alltmer influerad av privata och kommersiella satsningar. Att relatera till ny teknik, nuvarande trender och drivkrafter inom rymdindustrin är Jacob Ask is pursuing a Master of Science degree in Aerospace Engineering at KTH Royal Institute of Technology in Stockholm, Sweden. Christer Fuglesang is a professor in Space Travel, director of KTH Space Center and responsible for the Aerospace Engineering master program. He serves as the examiner for this master thesis project. Linda Lyckman is the Head of Business & Technology Innovation at SSC and supervisor for this master thesis project. komplext. Genom att undersöka och analysera identifierade trender och teknologier ämnar författaren urskilja de som kan komma att påverka industrin i störst utsträckning under det kommande decenniet. Bedömningar av marknadsmöjligheter och intervjuer har genomförts och i denna rapport presenteras ¨aven diskussioner och slutsatser relaterade till den typ av tjänster som Swedish Space Corporation erbjuder. Denna rapport har för avsikt att uppdatera läsaren om delar av den aktuella nulägesanalysen inom rymdindustrin, introducera koncept och ge relevanta kommentarer om viktiga trender.
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(9178595), Smriti Nandan Paul. "Orbital Perturbations for Space Situational Awareness." Thesis, 2020.
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Because of the increasing population of space objects, there is an increasing necessity to monitor and predict the status of the near-Earth space environment, especially of critical regions like geosynchronous Earth orbit (GEO) and low Earth orbit (LEO) regions, for a sustainable future. Space Situational Awareness (SSA), however, is a challenging task because of the requirement for dynamically insightful fast orbit propagation models, presence of dynamical uncertainties, and limitations in sensor resources. Since initial parameters are often not known exactly and since many SSA applications require long-term orbit propagation, long-term effects of the initial uncertainties on orbital evolution are examined in this work. To get a long-term perspective in a fast and efficient manner, this work uses analytical propagation techniques. Existing analytical theories for orbital perturbations are investigated, and modifications are made to them to improve accuracy. While conservative perturbation forces are often studied, of particular interest here is the orbital perturbation due to non-conservative forces. Using the previous findings and the developments in this thesis, two SSA applications are investigated in this work. In the first SSA application, a sensor tasking algorithm is designed for the detection of new classes of GEO space objects. In the second application, the categorization of near-GEO objects is carried out by combining knowledge of orbit dynamics with machine learning techniques.
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(6372689), Bryan David Little. "Optical Sensor Tasking Optimization for Space Situational Awareness." Thesis, 2019.
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In this work, sensor tasking refers to assigning the times and pointing directions for a sensor to collect observations of cataloged objects, in order to maintain the accuracy of the orbit estimates. Sensor tasking must consider the dynamics of the objects and uncertainty in their positions, the coordinate frame in which the sensor tasking is defined, the timing requirements for observations, the sensor capabilities, the local visibility, and constraints on the information processing and communication. This research focuses on finding efficient ways to solve the sensor tasking optimization problem. First, different coordinate frames are investigated, and it is shown that the observer fixed Local Meridian Equatorial (ground-based) and Satellite Meridian Equatorial (space-based) coordinate frames provide consistent sets of pointing directions and accurate representations of orbit uncertainty for use by the optimizers in solving the sensor tasking problem. Next, two classical optimizers (greedy and Weapon-Target Assignment) which rely on convexity are compared with two Machine Learning optimizers (Ant Colony Optimization and Distributed Q-learning) which attempt to learn about the solution space in order to approximate a global optimal solution. It is shown that the learning optimizers are able to generate better solutions, while the classical optimizers are more efficient to run and require less tuning to implement. Finally, the realistic scenario where the optimization algorithm receives no feedback before it must make the next decision is introduced. The Predicted Measurement Probability (PMP) is developed, and employed in a two sensor optimization framework. The PMP is shown to provide effective feedback to the optimization algorithm regarding the observations of each sensor.
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(9750503), Michael James Rose. "Optical Sensor Uncertainties and Variable Repositioning Times in the Single and Multi-Sensor Tasking Problem." Thesis, 2020.
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As the number of Resident Space Objects around Earth continues to increase, the need for an optimal sensor tasking strategy, specifically with Ground-Based Optical sensors, continues to be of great importance. This thesis focuses on the single and multi-sensor tasking problem with realistic optical sensor modeling for the observation of objects in the Geosynchronous Earth Orbit regime. In this work, sensor tasking refers to assigning the specific?c observation times and viewing directions of a single or multi sensor framework to either survey for or track new or existing objects. For this work specifically, the sensor tasking problem will seek to maximize the total number of Geosynchronous Earth Orbiting objects to be observed from a catalog of existing objects with a single and multi optical sensor tasking framework. This research focuses on the physical assumptions and limitations on an optical sensor, and how these assumptions affect the single and multi sensor tasking scenario. First, the concept of the probability of detection of a resident space object is calculated based on the viewing geometry of the resident space object. Then, this probability of detection is compared to the system that avoids the computational process by implementing a classical heuristic minimum elevation constraint to an electro-optical charged coupled optical sensor. It is shown that in the single and multi-sensor tasking scenario if the probability of detection is not considered in the sensor tasking framework, then a rigid elevation constraint of around 25o-35o is recommended for tasking Geosynchronous objects. Secondly, the topic of complete geo-coverage within a single night is explored. A sensor network proposed by Ackermann et al. (2018) is studied with and without the probability of detection considerations, and with and without uncertainties in the resident space objects' states. (then what you have). For the multi-sensor system, it is shown that with the assumed covariance model for this work, the framework developed by Ackermann et al. (2018) does not meet the design requirements for the cataloged Geosynchronous objects from March 19th, 2019. Finally, the concept of a variable repositioning time for the slewing of the ground-based sensors is introduced and compared to a constant repositioning time model. A model for the variable repositioning time is derived from data retrieved from the Purdue Optical Ground Station. This model is applied to a single sensor scenario. Optimizers are developed using the two repositioning time functions derived in this work. It is shown that the constant repositioning models that are greater than the maximum repositioning time produce results close to the variable repositioning solution. When the optimizers are tested, it is shown that there is a small increase in performance only when the maximum repositioning time is significant.
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(8766717), Alex M. Friedman. "Observability Analysis for Space Situational Awareness." Thesis, 2020.
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Space operations from the dawn of the Space Age have resulted in a large, and growing, resident space object population. However, the availability of sensor resources is limited, which presents a challenge to Space Situational Awareness applications. When direct communication with an object is not possible, whether that is due to a lack of access for active satellites or due to the object being characterized as debris, the only independent information source for learning about the resident space object population comes from measurements. Optical measurements are often a cost-effective method for obtaining information about resident space objects.
This work uses observability analysis to investigate the relationship between desired resident space object characteristics and the information resulting from ground-based optical measurements. Observability is a concept developed in modern control theory for evaluating whether the information contained within measurements is sufficient to describe the dynamical progression of a system over time. In this work, observability is applied to Space Situational Awareness applications to determine what object characteristic information can be recovered from ground-based optical measurements and under which conditions these determinations are possible. In addition, the constraints and limitations of applying observability to Space Situational Awareness applications are assessed and quantified.
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DeMars, Kyle Jordan. "Nonlinear orbit uncertainty prediction and rectification for space situational awareness." Thesis, 2010. http://hdl.handle.net/2152/ETD-UT-2010-12-2596.
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A new method for predicting the uncertainty in a nonlinear dynamical system is developed and analyzed in the context of uncertainty evolution for resident space objects (RSOs) in the near-geosynchronous orbit regime under the influence of central body gravitational acceleration, third body perturbations, and attitude-dependent solar radiation pressure (SRP) accelerations and torques. The new method, termed the splitting Gaussian mixture unscented Kalman filter (SGMUKF), exploits properties of the differential entropy or Renyi entropy for a linearized dynamical system to determine when a higher-order prediction of uncertainty reaches a level of disagreement
with a first-order prediction, and then applies a multivariate Gaussian splitting algorithm to reduce the impact of induced nonlinearity. In order to address the relative accuracy of the new method with respect to the more traditional approaches of the extended Kalman filter (EKF) and unscented Kalman filter (UKF), several concepts regarding the comparison of probability density functions (pdfs) are introduced and
utilized in the analysis.
The research also describes high-fidelity modeling of the nonlinear dynamical system which drives the motion of an RSO, and includes models for evaluation of the central body gravitational acceleration, the gravitational acceleration due to other celestial bodies, and attitude-dependent SRP accelerations and torques when
employing a macro plate model of an RSO. Furthermore, a high-fidelity model of the measurement of the line-of-sight of a spacecraft from a ground station is presented,
which applies light-time and stellar aberration corrections, and accounts for observer and target lighting conditions, as well as for the sensor field of view.
The developed algorithms are applied to the problem of forward predicting the time evolution of the region of uncertainty for RSO tracking, and uncertainty rectification via the fusion of incoming measurement data with prior knowledge. It is demonstrated that the SGMUKF method is significantly better able to forward predict the region of uncertainty and is subsequently better able to utilize new measurement data.text
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Biria, Ashley Darius. "Analytical approach to the design of optimal satellite constellations for space-based space situational awareness applications." Thesis, 2011. http://hdl.handle.net/2152/ETD-UT-2011-12-4941.
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In recent years, the accumulation of space debris has become an increasingly pressing issue, and adequately monitoring it is a formidable task for designated ground-based sensors. Supplementing the capabilities of these ground-based networks with orbiting sensing platforms would dramatically enhance the ability of such systems to detect, track, identify, and characterize resident space objects -- the primary goals of modern space situational awareness (SSA). Space-based space situational awareness (SBSSA), then, is concerned with achieving the stated SSA goals through coordinated orbiting sensing platforms. To facilitate the design of satellite constellations that promote SSA goals, an optimization approach is selected, which inherently requires a pre-defined mathematical representation of a cost index or measure of merit. Such representations are often analytically available, but when considering optimal constellation design for SBSSA applications, a closed-form expression for the cost index is only available under certain assumptions. The present study focuses on a subset of cases that admit exact representations. In this case, geometrical arguments are employed to establish an analytical formulation for the coverage area provided as well as for the coverage multiplicity. These analytical results are essential in validating numerical approximations that are able to simulate more complex configurations.text
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Gupta, Mini. "Analysis of the Representation of Orbital Errors and Improvement of their Modelling." Thesis, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-71535.
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In Space Situational Awareness (SSA), it is crucial to assess the uncertainty related to thestate vector of resident space objects (RSO). This uncertainty plays a fundamental role in, forexample, collision risk assessment and re-entry predictions. A realistic characterization of thisuncertainty is, therefore, necessary.The most common representation of orbital uncertainty is through a Gaussian (or normal)distribution. However, in the absence of new observations, the uncertainty grows over timeand the Gaussian representation is no longer valid under nonlinear dynamics like spacemechanics. This study evaluates the time when the uncertainty starts becoming non-Gaussianin nature. Different algorithms for evaluating the normality of a distribution were implemented andMonte Carlo tests were performed on them to assess their performance. Also, the distancesbetween distributions when they are propagated under linear and nonlinear algorithms werecomputed and compared to the results from the Monte Carlo statistics tests in order to predictthe time when the Gaussianity of the distribution breaks. Uncertainty propagation using StateTransition Tensors and Unscented Transform methods were also studied. Among theimplemented algorithms for evaluating the normality of a distribution, it was found thatRoyston’s method gives the best performance. It was also found that if the Normalized L 2distance between the linear and non-linear propagated distributions is greater than 95%, thenuncertainty starts to become non-Gaussian. In the best case scenario of unperturbed two-bodymotion, it is observed that the Gaussianity is preserved for at least three orbital periods in thecase of Low-Earth and Geostationary orbits when initial uncertainty corresponds to the meanprecision of the space debris catalog. If the initial variances are reduced, then Gaussianity ispreserved for a longer period of time. Time for which Gaussian assumption is valid on orbitaluncertainty is also dependent on the initial mean anomaly. Effect of coordinatestransformation on Gaussianity validity time is also analyzed by considering uncertainty inCartesian, Keplerian and Poincaré coordinate systems. This study can therefore be used to improve space debris cataloguing.
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Takano, Andrew Takeshi. "Numerical analysis and design of satellite constellations for above the horizon coverage." Thesis, 2010. http://hdl.handle.net/2152/ETD-UT-2010-12-2594.
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As near-Earth space becomes increasingly crowded with spacecraft and debris, the need for improved space situational awareness has become paramount. Contemporary ground-based systems are limited in the detection of very small or dim targets. In contrast, space-based systems, above most atmospheric interference, can achieve significant improvements in dim target detection by observing targets against a clutter-free space background, i.e. targets above the horizon (ATH). In this study, numerical methods for the evaluation of ATH coverage provided by constellations of satellites are developed. Analysis of ATH coverage volume is reduced to a planar analysis of cross-sectional coverage area in the orbit plane. The coverage model performs sequences of boolean operations between polygons representing cross-sections of satellite sensor coverage regions and regions of interest, returning the coverage area at the desired multiplicity. This methodology allows investigation of any coverage multiplicity for planar constellations of any size, and use of arbitrary sensor profiles and regions of interest. The implementation is applied to several constellation design problems demonstrating the utility of the numerical ATH coverage model in a constellation design process.text
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(8817071), Patrick Michael Kelly. "Optical Astrometry and Orbit Determination." Thesis, 2020.
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The resident space object population in the near-Earth vicinity has steadily increased since the dawn of the space age. This population is expected to increase drastically in the near future as the realization of proposed mega-constellations is already underway. The resultant congestion in near-Earth space necessitates the availability of more complete and more accurate satellite tracking information to ensure the continued sustainable use of this environment. This work sets out to create an operational system for the delivery of accurate satellite tracking information by means of optical observation. The state estimates resulting from observation series conducted on a GPS satellite and a geostationary satellite are presented and compared to existing catalog information. The satellite state estimate produced by the system is shown to outperform existing two-line element results. Additionally, the statistical information provided by the processing pipeline is evaluated and found to be representative of the best information available for the satellites true state.
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(8694222), Daigo Kobayashi. "Exploration of Compressed Sensing for Satellite Characterization." Thesis, 2020.
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This research introduces a satellite characterization method based on its light curve by utilizing and adapting the methodology of compressed sensing. Compressed sensing is a mathematical theory, which is established in signal compression and which has recently been applied to an image reconstruction by single-pixel camera observation. In this thesis, compressed sensing in the use of single-pixel camera observations is compared with a satellite characterization via non-resolved light curves. The assumptions, limitations, and significant differences in utilizing compressed sensing for satellite characterization are discussed in detail. Assuming a reference observation can be used to estimate the so-called sensing matrix, compressed sensing enables to approximately reconstruct resolved satellite images revealing details about the specific satellite that has been observed based solely on non-resolved light curves. This has been shown explicitly in simulations. This result implies the great potential of compressed sensing in characterizing space objects that are so far away that traditional resolved imaging is not possible.
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Ottesen, David Ryan. "The dynamics of deployment and observation of a rigid body spacecraft system in the linear and non-linear two-body problem." 2012. http://hdl.handle.net/2152/19685.
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Modern space situational awareness entails the detection, tracking, identification, and characterization of resident space objects. Characterization is typically accomplished through the use of ground and space based sensors that are able to identify some specific physical feature, monitor unique dynamical behaviors, or deduce some information about the material properties of the object. The present investigation considers the characterizaiton aspects of situational awareness from the perspective of a close-proximity formation reconnaissance mission. The present study explores both relative translational and relative rotational motion for deployment of a spacecraft and observation of a resident space object. This investigation is motivated by specific situations in which characterization with ground or fixed space based sensors is insufficient. Instead, one or more vehicles are deployed in the vicinity of the object of interest. These could be, for instance, nano-satellites with imaging sensors. Nano-satellites offer a low-cost and effective technological platform, which makes consideration of the proposed scenario more feasible. Although the motivating application is rooted in space situational awareness, the techniques explored are generally applicable to flight in the vicinity of asteroids, and both cooperative vs. non-cooperative resident space objects. The investigation is initially focused on identifying the key features of the relative dynamics that are relevant to space situational awareness applications. Subsequently, effective spacecraft control techniques are considered to achieve the reconnaissance goals.text
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(8918840), Christopher Y. Jang. "Modeling and Detecting Orbit Observation Errors Using Statistical Methods." Thesis, 2020.
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In the globally collaborative effort of maintaining an accurate space catalog, it is of utmost importance for ground tracking stations to provide observations which can be used to update and improve the catalog. However, each tracking station is responsible for viewing thousands of objects in a limited window of time. Limitations in sensor capabilities, human error, and other circumstances inevitably result in erroneous, or unusable, data, but when receiving information from a tracking station, it may be difficult for the end-user to determine a data set's usability. Variables in equipment, environment, and processing create uncertainties when computing the positions and orbits of the satellites. Firstly, this research provides a reference frame for what degrees of errors or biases in equipment translate to different levels of orbital errors after a least squares orbit determination. Secondly, using just an incoming data set's angle error distribution compared to the newly determined orbit, statistical distribution testing is used to determine the validity and usability of the newly received data set. In the context of orbit position uncertainty, users are then able to communicate and relay the uncertainties in the data they share while assessing incoming data for potential sources of error.