Solar transient eruptions are the main cause of interplanetary-magnetospheric disturbances leading to the phenomena known as geomagnetic storms. Eruptive solar events such as coronal mass ejections (CMEs) are currently considered the main cause of geomagnetic storms (GMS). GMS are strong perturbations of the Earth’s magnetic field that can affect space-borne and ground-based technological systems. The solar-terrestrial impact on modern technological systems is commonly known as Space Weather. Part of the research study described in this thesis was to investigate and establish a relationship between GMS (periods with Dst ≤ −50 nT) and their associated solar and interplanetary (IP) properties during solar cycle (SC) 23. Solar and IP geoeffective properties associated with or without CMEs were investigated and used to qualitatively characterise both intense and moderate storms. The results of this analysis specifically provide an estimate of the main sources of GMS during an average 11-year solar activity period. This study indicates that during SC 23, the majority of intense GMS (83%) were associated with CMEs, while the non-associated CME storms were dominant among moderate storms. GMS phenomena are the result of a complex and non-linear chaotic system involving the Sun, the IP medium, the magnetosphere and ionosphere, which make the prediction of these phenomena challenging. This thesis also explored the predictability of both the occurrence and strength of GMS. Due to their nonlinear driving mechanisms, the prediction of GMS was attempted by the use of neural network (NN) techniques, known for their non-linear modelling capabilities. To predict the occurrence of storms, a combination of solar and IP parameters were used as inputs in the NN model that proved to predict the occurrence of GMS with a probability of 87%. Using the solar wind (SW) and IP magnetic field (IMF) parameters, a separate NN-based model was developed to predict the storm-time strength as measured by the global Dst and ap geomagnetic indices, as well as by the locally measured K-index. The performance of the models was tested on data sets which were not part of the NN training process. The results obtained indicate that NN models provide a reliable alternative method for empirically predicting the occurrence and strength of GMS on the basis of solar and IP parameters. The demonstrated ability to predict the geoeffectiveness of solar and IP transient events is a key step in the goal towards improving space weather modelling and prediction.

The paper describes the background and concepts behind a master’s thesis platform known as COMET (Constrained Optimization of Multiple-dimensions for Efficient Trajectories) created for mission designers to determine and evaluate suitable interplanetary trajectories. This includes an examination of the improvements to the global optimization algorithm, Differential Evolution, through a cascading search space pruning method and decomposition of optimization parameters. Results are compared to those produced by the European Space Agency’s Advanced Concept Team’s Multiple Gravity Assist Program. It was found that while discrepancies in the calculation of ΔV’s for flyby maneuvers exist between the two programs, COMET showed a noticeable improvement in its ability to avoid premature convergence and find highly isolated solutions.

This concept of calculating, optimizing, and utilizing a trajectory known as a ``Free Return Trajectory" to facilitate spacecraft rendezvous with Near-Earth Asteroids is presented in this dissertation. A Free Return Trajectory may be defined as a trajectory that begins and ends near the same point, relative to some central body, without performing any deterministic velocity maneuvers (i.e., no maneuvers are planned in a theoretical sense for the nominal mission to proceed). Free Return Trajectories have been utilized previously for other purposes in astrodynamics, but they have not been previously applied to the problem of Near-Earth Asteroid rendezvous. Presented here is a series of descriptions, algorithms, and results related to trajectory initial guess calculation and optimal trajectory convergence. First, Earth-centered Free Return Trajectories are described in a general manner, and these trajectories are classified into several families based on common characteristics. Next, these trajectories are used to automatically generate initial conditions in the three-body problem for the purpose of Near-Earth Asteroid rendezvous. For several bodies of interest, example initial conditions are automatically generated, and are subsequently converged, resulting in feasible, locally-optimal, round-trip trajectories to Near-Earth Asteroids utilizing Free Return Trajectories. Subsequently, a study is performed on using an unpowered flyby of the Moon to lower the overall DV cost for a nominal round-trip voyage to a Near-Earth Asteroid. Using the Moon is shown to appreciably decrease the overall mission cost. In creating the formulation and algorithms for the Lunar flyby problem, an initial guess routine for generic planetary and lunar flyby tours was developed. This continuation algorithm is presented next, and details a novel process by which ballistic trajectories in a simplistic two-body force model may be iteratively converged in progressively more realistic dynamical models until a final converged ballistic trajectory is found in a full-ephemeris, full-dynamics model. This procedure is useful for constructing interplanetary transfers and moon tours in a realistic dynamical framework; an interplanetary and an inter-moon example are both shown. To summarize, the material in this dissertation consists of: novel algorithms to compute Free Return Trajectories, and application of the concept to Near-Earth Asteroid rendezvous; demonstration of cost-savings by using a Lunar flyby; and a novel routine to transfer trajectories from a simplistic model to a more realistic dynamical representation. / text

Les ceintures de radiation correspondent à la région de la magnétosphère dans laquelle se trouvent les particules de hautes énergies. Le couplage entre le vent solaire et la magnétosphère donne lieu à des variations des flux de particules sur plusieurs ordres de grandeurs. L’objectif de cette thèse est d’observer et caractériser ces variations de flux d’électrons au passage de différents types d’événements tels que les régions d’interaction en co-rotation (CIRs) et les éjections de masse coronale interplanétaires (ICMEs). Pour cela, nous avons traité et analysé les données de plusieurs types: paramètres du vent solaire, indices géomagnétiques et flux d’électrons dans les ceintures de radiation. Dans les trois premiers chapitres, nous rendons compte de la complexité de l’environnement spatial Terrestre et présentons les différentes données utilisées. Les travaux de thèse sont ensuite organisés en quatre chapitres. Premièrement, nous utilisons les mesures des satellites NOAA-POES afin de caractériser les flux d’électrons dans les ceintures. Nous étudions ensuite les différences de variations de flux causées par les CIRs et les ICMEs en fonction de l’énergie des électrons et du paramètre L*. Après avoir montré le fort lien entre les intensités d’orages magnétiques et les variations de flux, nous nous focalisons sur les ICMEs et la variabilité des orages qu’elles causent. Enfin, nous insistons sur l’importance des enchaînements d’événements. Après avoir quantifié la forte tendance qu’ont les ICMEs à former des séquences, nous réalisons une étude statistique sur les orages qu’elles causent, puis trois études de cas afin d’illustrer leurs effets sur les ceintures. / The radiation belts are the toroidal region within the inner magnetosphere where high energetic particles are located. The coupling between the solar wind and the magnetosphere leads to strong variations of particle fluxes that can therefore increase or decrease over several orders of magnitude. The aim of this thesis is to observe and characterize the variations of fluxes during the crossing of several types of events originating from the sun such as Corotating Interaction Regions (CIRs) and Interplanetary Coronal Mass Ejections (ICMEs). To do so, we processed and analyzed the data of various types : solar wind parameters, geomagnetic indices, and electron fluxes within the radiation belts. In the three first chapters, we report on the complexity of the Terrestrial space environment and we present the Solar-Terrestrial system and the data used. Then, our work is organized around four chapters. First, we characterized the electron fluxes within the radiation belts as measured by the NOAA-POES spacecrafts. Then, we studied the difference between the variations of fluxes caused by the CIRs and the ICMEs depending on the energy and the L* parameter. After establishing strong links between the intensity of magnetic storms and the variations of fluxes, we focused on the ICMEs and the variability of the related magnetic storms. Eventually, we emphasized the importance of the sequences of events. After quantifying the trend of the ICMEs to form sequences, we performed a statistical study on the magnetic storms caused by such sequences. Finally three study cases were performed in order to illustrate the various possible effects on the radiation belts.

A meteor observed with the naked eye is colloquially called a shooting star. The streak of light is generated by an extra-terrestrial particle, a meteoroid, entering the Earth’s atmosphere. The term meteor includes both luminosity detectable by optical means and ionization detectable by radar. The radar targets of meteor head echoes have the same motion as the meteoroids on their atmospheric flight and are relatively independent of aspect angle. They appear to be compact regions of plasma created at around 100 km altitude and have no appreciable duration. This thesis reviews the meteor head echo observations carried out with the tristatic 930 MHz EISCAT UHF radar system during four 24h runs between 2002 and 2005, and a 6h run in 2003 with the monostatic 224 MHz EISCAT VHF radar. It contains the first strong observational evidence of a submillimeter-sized meteoroid breaking apart into two distinct fragments. This discovery promises to be useful in the further understanding of the interaction processes of meteoroids with the Earth’s atmosphere and thus also the properties of interplanetary/interstellar dust. The tristatic capability of the EISCAT UHF system makes it a unique tool for investigating the physical properties of meteoroids and the meteor head echo scattering process. The thesis presents a method for determining the position of a compact radar target in the common volume of the antenna beams and demonstrates its applicability for meteor studies. The inferred positions of the meteor targets are used to estimate their velocities, decelerations, directions of arrival and radar cross sections (RCS) with unprecedented accuracy. The head echoes are detected at virtually all possible aspect angles all the way out to 130° from the meteoroid trajectory, limited by the antenna pointing directions. The RCS of individual meteors simultaneously observed with the three receivers are equal within the accuracy of the measurements with a very slight trend suggesting that the RCS decreases with increasing aspect angle. A statistical evaluation of the measurement technique shows that the determined Doppler velocity agrees with the target range rate. This demonstrates that no contribution from slipping plasma is detected and that the Doppler velocities are unbiased within the measurement accuracy. The velocities of the detected meteoroids are in the range of 19-70 km/s, but with very few detections at velocities below 30 km/s. The thesis compares observations with a numerical single-body ablation model, which simulates the physical processes during meteoroid flight through the atmosphere. The estimated meteoroid masses are in the range of 10-9 - 10-5.5 kg. / Meteorer är ljusfenomen på natthimlen som i vardagligt tal kallas fallande stjärnor. Ljusstrimmorna alstras av meteoroider, små partiklar på banor genom solsystemet, som kolliderar med jordens atmosfär. Förutom ljus genererar meteoroider regioner av joniserat plasma, som är detekterbara med radar. Meteoriska huvudekon tycks komma från kompakta radarmål på ungefär 100 km höjd och rör sig genom atmosfären med de infallande meteoroidernas hastighet. Huvudekons signalstyrka förefaller oberoende av vinkeln mellan radarmålens rörelseriktning och riktningen från vilken radiovågorna infaller och sprids. Avhandlingen sammanfattar huvudekoobservationer från fyra 24-timmarsmätningar mellan 2002 och 2005 med det trestatiska 930 MHz EISCAT UHF-radarsystemet och en 6-timmarsmätning under 2003 med den monostatiska 224 MHz EISCAT VHF-radarn. Avhandlingen innehåller den första observationella bekräftelsen på att en meteoroid av sub-millimeterstorlek faller sönder i två distinkta fragment i atmosfären. Upptäckten är betydelsefull för studier av meteoroiders växelverkansprocesser med atmosfären och interplanetärt/interstellärt stofts materialegenskaper. EISCAT UHF-systemet består av tre vitt åtskilda mottagarstationer, vilket gör det till ett unikt mätinstrument för studier av meteoroiders egenskaper och hur radiovågor sprids från de radarmål som ger upphov till huvudekon. Avhandlingen presenterar en metod med vilken ett radarmåls position kan bestämmas om det detekteras simultant med de tre mottagarna. Metoden används till att med hög noggrannhet beräkna meteorers radartvärsnitt samt meteoroiders hastighet och atmosfärsinbromsning. De detekterade huvudekona genereras av meteoroider med i princip alla av mätgeometrin tillåtna rörelseriktningar i förhållande till radarstrålen, ända ut till 130° från radiovågornas spridningsriktning. Enskilda meteorers radartvärsnitt är likvärdiga inom mätnoggrannheten i de tre mottagarstationernas dataserier, men en svag trend antyder att radartvärsnittet minskar med ökande vinkel mellan meteoroidernas rörelseriktning och spridningsriktningen. En statistisk utvärdering av mättekniken visar att den uppmätta dopplerhastigheten stämmer överens med radarmålens flygtidshastighet. Detta innebär att dopplerhastigheterna är väntevärdesriktiga och opåverkade av bidrag från det spår av plasma som meteoroiderna lämnar efter sig. De uppmätta hastigheterna är 19-70 km/s, men bara ett fåtal detekterade meteoroider är långsammare än 30 km/s. Meteoroidmassorna är uppskattade till 10-9 – 10-5.5 kg genom jämförelser av observationerna med simuleringar av meteoroiders färd genom atmosfären i en numerisk ablationsmodell.

With the goal to continue interplanetary exploration and search for past or existent life on Mars, software and hardware for unmanned subsurface drills are being developed. Unlike drilling on Earth, interplanetary exploration drills operate with very low available power and require on-board integrated health monitoring systems, with quick-response recovery procedures, under complete autonomous operations. As many drilling faults are not known a priori, Earth-based direction and control of an unmanned interplanetary drilling operation is not practical. Such missions also require advanced robotic systems that are more susceptible to structural and mechanical failures, which motivates a need for structural health monitoring techniques relevant to interplanetary exploration systems. Structural health monitoring (SHM) is a process of detecting damage or other types of defects in structural and mechanical systems that have the potential to adversely affect the current or future performance of these systems. Strict requirements for interplanetary drilling missions create unique research problems and challenges compared with SHM procedures and techniques developed to date. These challenges include implementing sensors and devices that do not interfere with the drilling operation, producing "real-time" diagnostics of the drilling condition, and developing an automation procedure for complete autonomous operations. Thus, the completed thesis work presents basic research leading to the dynamic analysis of rotating structures with specific application to interplanetary subsurface drill systems, and the formulation of an autonomous, real-time, dynamics-based SHM technique for drilling applications. This includes modeling and validating the structural dynamic system, with and without damage or faults, for a prototype interplanetary subsurface drill, exploring the use of Laser Doppler Velocimeter sensors for use in real-time SHM, developing signal filters to remove inherent harmonic components from the dynamic signal of rotating structures, developing an automation procedure with the associated software, and validating the SHM system through laboratory experiments and field tests. The automated dynamics-based structural health monitoring technique developed in this thesis presents advanced research accomplishments leading to real-time, autonomous SHM, and it has been validated on an operating dynamic system in laboratory and field tests. The formulated SHM and drilling operation also met or exceeded all specified requirements. Other major contributions of this thesis work include the formulation and demonstration of real-time, autonomous SHM in rotating structures using Laser Doppler Velocimeter sensors.

Le premier objectif de cette thèse est de bien comprendre les propriétés de la dynamique du problème circulaire restreint des trois corps et de les utiliser pour calculer des missions pour satellites pourvus de moteurs à faible poussée. Une propriété fondamentale est l'existence de variétés invariantes associées à des orbites périodiques autour des points de \bsc{Lagrange}. En suivant l'idée de l'\emph{Interplanetary Transport Network}, la connaissance et le calcul des variétés invariantes, comme courants gravitationnels, sont cruciaux pour le \emph{design} de missions spatiales. Une grande partie de ce travail de thèse est consacrée au développement de méthodes numériques pour calculer le transfert entre variétés invariantes de façon optimale. Le coût que l'on cherche alors à minimiser est la norme $L^{1}$ du contrôle car elle est équivalente à minimiser la consommation des moteurs. On considère aussi la norme $L^{2}$ du contrôle car elle est, numériquement, plus facile à minimiser. Les méthodes numériques que nous utilisons sont des méthodes indirectes rendues plus robustes par des méthodes de continuation sur le coût, sur la poussée, et sur l'état final. La mise en œuvre de ces méthodes repose sur l'application du Principe du Maximum de Pontryagin. Les algorithmes développés dans ce travail permettent de calculer des missions réelles telles que des missions entre des voisinages des points de \bsc{Lagrange}. L'idée principale est d'initialiser un tir multiple avec une trajectoire admissible composée de parties contrôlées (des transferts locaux) et de parties non-contrôlées suivant la dynamique libre (les variétés invariantes). Les méthodes mises au point ici, sont efficaces et rapides puisqu'il suffit de quelques minutes pour obtenir la trajectoire optimale complète. Enfin, on développe une méthode hybride, avec à la fois des méthodes directes et indirectes, qui permettent d'ajuster la positions des points de raccord sur les variétés invariantes pour les missions à grandes variations d'énergie. Le gradient de la fonction valeur est donné par les valeurs des états adjoints aux points de raccord et donc ne nécessite pas de calculs supplémentaire. Ainsi, l'implémentation de algorithme du gradient est aisée. / The first objective of this work is to understand the dynamical properties of the circular restricted three body problem in order to use them to design low consumption missions for spacecrafts with a low thrust engine. A fundamental property is the existence of invariant manifolds associated with periodic orbits around Lagrange points. Following the Interplanetary Transport Network concept, invariant manifolds are very useful to design spacecraft missions because they are gravitational currents. A large part of this work is devoted to designing a numerical method that performs an optimal transfer between invariant manifolds. The cost we want to minimize is the $L^{1}$-norm of the control which is equivalent to minimizing the consumption of the engines. We also consider the $L^{2}$-norm of the control which is easier to minimize numerically. The numerical methods are indirect ones coupled with different continuations on the thrust, on the cost, and on the final state, to provide robustness. These methods are based on the application of the Pontryagin Maximum Principal. The algorithms developed in this work allow for the design of real life missions such as missions between the realms of libration points. The basic idea is to initialize a multiple shooting method with an admissible trajectory that contains controlled parts (local transfers) and uncontrolled parts following the natural dynamics (invariant manifolds). The methods developed here are efficient and fast (less than a few minutes to obtain the whole optimal trajectory). Finally, we develop a hybrid method, with both direct and indirect methods, to adjust the position of the matching points on the invariant manifolds for missions with large energy gaps. The gradient of the value function is given by the values of the costates at the matching points and does not require any additional computation. Hence, the implementation of the gradient descent is easy.

Title: Evolution of Interplanetary Coronal Mass Ejections Author: Andrii Lynnyk Department: Department of Surface and Plasma Science Supervisor: RNDr. Marek Vandas, DrSc. e-mail address: vandas@ig.cas.cz Abstract: This thesis deals with deformation of the Interplanetary Coronal Mass Ejections (ICMEs) and their sub-class Magnetic Clouds (MCs) during their propagation in the Solar Wind (SW). The statistical study of the expanded MCs has shown that expansion greatly affects the MC internal magnetic field. We had shown that this influence is more clear for the MCs observed close to their axes. The study of the stand-off shock distance in front of the supersonic ICME confirms a smooth deformation of the ICMEs along their path from the Sun into interplanetary space. We observed that this deformation is increasing with the velocity of the ICME. This study also confirmed the difference in sheaths that are created in front of expanding and non-expanding ICMEs. We found that velocity distribution inside the MC is not uniform and it has large fluctuations. We found that the MC cross-section is usually strongly deformed. Keywords: interplanetary coronal mass ejection, magnetic cloud, magnetosheath, flux rope, magnetic field, shock, fitting

Coronal Mass Ejections (CMEs) are considered to be one of the most energetic events in the heliosphere. Capable of inducing geomagnetic storms on Earth that can cause damage to electronics, a pillar which the modern society we live in leans heavily upon. Being able to accurately predict the arrival of CMEs would present us with the ability to issue timely warnings to authorities and commercial actors, allowing for protective measures to be put in place minimizing the damage. In this study the predicted arrival times and speeds from the Drag Based Model (DBM) and Drag Based Ensemble Model (DBEM) were compared to observational data from a set of 12 events containing fast, Earth-directed Halo CMEs and their corresponding shocks. Although DBM was developed to model CME propagation, varying some parameters allow it to be used for estimating shock/sheath arrival. The results presented in this study indicate that on average DBM performs best when the drag-parameter γ is in the range 0.2 ≤ γ ≤ 0.3. However the variability in the results show that determining a universal value of γ for fast CMEs does not increase the consistency in the model's performance. For completeness, further investigation is needed to account for not only halo CMEs. This will allow to test broader range of variation in the DBEM input parameters.

Obstacles faced in planetary surface exploration require innovation in many areas, primarily that of robotics. To be able to study interesting areas that are by current means hard to reach, such as steep slopes, ravines, caves andlava tubes, the surface vehicles of today need to be modified or augmented. Oneaugmentation with such a goal is PHALANX (Projectile Hordes for AdvancedLong-term and Networked eXploration), a prototype system being developed atthe NASA Ames Research Center. PHALANX uses remote deployment of expendablesensor nodes from a lander or rover vehicle. This enables in-situ measurementsin hard-to-reach areas with reduced risk to the rover. The deployed sensornodes are equipped with capabilities to transmit data wirelessly back to therover and to form a network with the rover and other nodes. Knowledge of the location of deployed sensor nodes and the momentary locationof the rover is greatly desired. PHALANX can be of aid in this aspect as well.With the addition of inter-node and rover-to-node range measurements, arange-based network SLAM (Simultaneous Localization and Mapping) system can beimplemented for the rover to use while it is driving within the network. Theresulting SLAM system in PHALANX shares characteristics with others in the SLAM literature, but with some additions that make it unique. One crucial additionis that the rover itself deploys the nodes. Another is the ability for therover to more accurately localize deployed nodes by external sensing, such asby utilizing the rover cameras. In this thesis, the SLAM of PHALANX is studied by means of computer simulation.The simulation software is created using real mission values and valuesresulting from testing of the PHALANX prototype hardware. An overview of issuesthat a SLAM solution has to face as present in the literature is given in thecontext of the PHALANX SLAM system, such as poor connectivity, and highlycollinear placements of nodes. The system performance and sensitivities arethen investigated for the described issues, using predicted typical PHALANXapplication scenarios. The results are presented as errors in estimated positions of the sensor nodesand in the estimated position of the rover. I find that there are relativesensitivities to the investigated parameters, but that in general SLAM inPHALANX is fairly insensitive. This gives mission planners and operatorsgreater flexibility to prioritize other aspects important to the mission athand. The simulation software developed in this thesis work also has thepotential to be expanded on as a tool for mission planners to prepare forspecific mission scenarios using PHALANX.