This thesis is a feasibility study for a crewed mission to a Near Earth Asteroid (NEA). An alternate dual-launch architecture is proposed and analyzed against a more established architecture. Instead of a rendezvous in a low-Earth parking orbit, the new architecture performs the rendezvous while the two spacecraft are on an Earth-escape trajectory to the destination NEA. After selecting a target asteroid, 2000 SG344, each architecture will have its best mission compared to the best mission of the other architecture. Using the new architecture, a mission is created to the chosen NEA, 2000 SG344. A back-up Orion MPCV and a Habitation Module are launched first on a cargo configuration SLS. A crew of two astronauts is launched two hours later in the primary Orion MPCV by a crewed configuration SLS. Both of these launches are on an Earth-escape trajectory and begin rendezvous after two full days in outer space. The completed spacecraft journeys the rest of the trip to the NEA. For a period of eight days, the spacecraft remains in a tight control sphere near the asteroid by using a control algorithm and the rendezvous thrusters. The astronauts have this period to perform their EVAs and accomplish their mission objectives at the NEA. The spacecraft then departs the NEA and returns to Earth. The entire mission is 134 days and requires 2.054 km/s of Delta-v maneuvers to complete. An analysis of multiple Lambert's methods is also done due to their extensive use in this thesis. Many of the most popular Lambert algorithms are compared by evaluating each on its accuracy, speed, and singularities. The best Lambert method to use for the orbital analysis in this paper is Battin's method because it is accurate, quick, and robust for all cases that will be observed.

Project Upsilon is a proposed NASA Flagship Class, Uranus Orbiter and Probe mission concept to investigate Uranus' planetary magnetic field and atmosphere. Three spacecraft - the Upsilon-0 Propulsion Module, the Upsilon-1 Science Orbiter, and the Upsilon-2 Atmosphere Probe - shall be implemented to meet needs, goals, and objectives as stated by the NASA Solar System Planetary Science Decadal Survey 2013-2022. Upsilon-0 shall be expended in order to complete orbital capture about Uranus. Upsilon-1 shall study Uranus' planetary magnetic field, obtaining real-time measurements for nominally 20 months within the first two years of arrival; and for as long as possible after the first two years, as part of an extended science mission. Upsilon-2 shall be descended into Uranus' cloud tops to obtain physical data and imagery well into the atmosphere's depths. Chemical propulsion is employed in place of solar-electric propulsion, with regard to the interplanetary system-level trade tree. The interplanetary trajectory requires a single un-powered flyby of Jupiter, selected among several flyby node configurations. The science orbit produces nearly repeating latitude-longitude tracks over a rotating Uranus. The statistical estimation method combines an orbit determination model with respect to Uranus' flattening, and a simple magnetic dipole model for field line modeling. A 7-year period is allotted for the technology research and development, and the testing and verification stages of the project life cycle; the interplanetary journey to Uranus requires 21 years; and the nominal in-situ operation lifetime is 2 years. The Project Upsilon spacecraft launch in 2021 to "revolutionize our understanding of ice giant properties and processes, yielding significant insight into their evolutionary history"; contributing to the Planetary Science Decadal Survey's, and NASA's, key planetary science and deep space exploration visions. / text

This dissertation introduces novel techniques for exploiting the environmental aerodynamic forces to actively control the attitude of the spacecraft operating in the lower and middle thermosphere. It includes both simulations and real spacecraft attitude determination and control subsystem development, which provide a complete picture of the application of the aerodynamic forces to benefit space missions that are operating very close to Earth, as well as contribute to the knowledge of rarefied gas aerodynamics in the lower and middle part of the thermosphere. The research starts by reviewing the current progress of thermosphere science and rarefied gas aerodynamics to construct a high fidelity aerodynamic model for spacecraft operating in the rarefied gas (mainly atomic oxygen) environment in very low Earth orbits (below 450 km) and following by a brief system level analysis of the benefits and challenges for the spacecraft flying lower to Earth. A real spacecraft is also developed to validate of the application of the aerodynamic forces for attitude control. The aspect of the design included in this dissertation focuses mainly on the attitude determination and control system development of satellite. The CubeSat has a generic design with deployable solar panels that can be rotated to control the aerodynamic torques. Based on the common attitude control requirements of spacecraft operating in very low Earth orbits, and the hardware capability of the satellite three novel orbital aerodynamic attitude control strategies are proposed: Energy Optimized B-dot Detumbling into an Aerostable State; Active Orbital Aerodynamic Coarse Pitch/Yaw Control; a 3-axis Orbital Aerodynamic Torques Adaptive Sliding Mode Control. The control performance for each control algorithm is validated numerically in high-fidelity attitude propagators. Knowledge of the thermospheric winds is important as they influence the control performance and the dynamic response of the spacecraft, aerostable designs steering into the thermosphere wind vector. Two novel computational methods to measure the thermospheric wind from the dynamic response of the spacecraft due to aerodynamic forces are proposed. The in-situ measured wind vector benefits the attitude observation in the feedback control systems, which helps to improve the adapting performance and to increase the control accuracy. The proposed novel aerodynamic attitude control algorithms can be adapted for similar spacecraft operating in the very low Earth orbits with modifications to the deployable solar panels or adding movable aerodynamic control surfaces. In addition, this proposed orbital aerodynamic attitude control system works not only in the very low Earth orbits but can also be potentially implemented for spacecraft operating in the rarefied gas region of the atmospheres of other planets.

The development of the Surface Albedo Treatment System (SATS) onboard a spacecraft mission to the near earth asteroid (NEA) Apophis in 2012 is an innovative concept of deflecting NEAs from possible impact with the Earth through altering the Yarkovsky effect, a non-secular force in the solar system due to uneven surface thermal emission most profoundly affecting small rotating bodies subjected to sunlight. Though this force is small, its magnitude can be dramatic if extended over a period of time and if it uses the close approach of an asteroid near Earth to magnify the perturbation. The payload dispenses colored powder called albedo changing particles (ACPs) onto the surface changing its albedo and indirectly the surface temperature which changes the Yarkovsky effect. This study gives an in-depth description of both computational and experimental parts of the design of this system with primary focus on initial ground test setup. The initial experiments proposed to design the SATS is outlined in detail and justified by the mission criterion of interest as well as modeling the actual dispersal on the surface.

No description available.

The 2010 National Space Policy of the United State of America introduced by President Obama directed NASA to set far reaching exploration milestones that included a crewed mission to a Near Earth Asteroid by 2025 and a crewed mission to Martian orbit by the mid-2030s. The policy was directly influenced by the recommendations of the 2009 Review of United States Human Space Flight Plans Committee, which called for an evolutionary approach to human space exploration and emphasized the criticality of budgetary, programmatic, and program sustainability. One potential method of improving the sustainability of exploration architectures is the utilization of orbital propellant depots with commercial launch services. In any exploration architecture, upwards of seventy percent of the mass required in orbit is propellant. A propellant depot based architecture allows propellant to be delivered in small increments using existing commercial launch vehicles, but will require three to five times the number of launches as compared to the using the NASA planned 70 to 130 metric ton heavy lift launch system. Past studies have shown that the utilization of propellant depots in exploration architectures have the potential of providing the sustainability that the Review of United States Human Space Flight Plans Committee emphasized. However, there is a lack of comprehensive analysis to determine the feasibility of propellant depots within the framework of human space exploration. The objective of this research is to measure the feasibility of a propellant depot and commercial launch based exploration architecture by stochastic assessment of technical, reliability, and economic risks. A propellant depot thermal model was developed to analyze the effectiveness of various thermal management systems, determine their optimal configuration, quantify the uncertainties in the system models, and stochastically compute the performance feasibility of the propellant depot system. Probabilistic cost analysis captured the uncertainty in the development cost of propellant depots and the fluctuation of commercial launch prices, and, along with the cost of launch failures, provided a metric for determining economic feasibility. Probabilistic reliability assessments using the launch schedule, launch reliability, and architecture requirements of each phase of the mission established launch success feasibility. Finally, an integrated stochastic optimization was performed to determine the feasibility of the exploration architecture. The final product of this research is an evaluation of propellant depots and commercial launch services as a practical method to achieving economic sustainability for human space exploration. A method for architecture feasibility assessment is demonstrated using stochastic system metrics and applied in the evaluation of technical, economic, and reliability feasibility of orbital propellant depots and commercial launch based exploration architectures. The results of the analysis showed the propellant depots based architectures to be technically feasible using current commercial launch vehicles, economically feasible for having a program budget less than $4 billion per year, and have launch reliability approaching the best single launch vehicle, Delta IV, with the use of redundant vehicles. These results serve to provide recommendations on the use of propellant depots in exploration architectures to the Moon, Near Earth Objects, Mars, and beyond.The 2010 National Space Policy of the United State of America introduced by President Obama directed NASA to set far reaching exploration milestones that included a crewed mission to a Near Earth Asteroid by 2025 and a crewed mission to Martian orbit by the mid-2030s. The policy was directly influenced by the recommendations of the 2009 Review of United States Human Space Flight Plans Committee, which called for an evolutionary approach to human space exploration and emphasized the criticality of budgetary, programmatic, and program sustainability. One potential method of improving the sustainability of exploration architectures is the utilization of orbital propellant depots with commercial launch services. In any exploration architecture, upwards of seventy percent of the mass required in orbit is propellant. A propellant depot based architecture allows propellant to be delivered in small increments using existing commercial launch vehicles, but will require three to five times the number of launches as compared to the using the NASA planned 70 to 130 metric ton heavy lift launch system. Past studies have shown that the utilization of propellant depots in exploration architectures have the potential of providing the sustainability that the Review of United States Human Space Flight Plans Committee emphasized. However, there is a lack of comprehensive analysis to determine the feasibility of propellant depots within the framework of human space exploration. The objective of this research is to measure the feasibility of a propellant depot and commercial launch based exploration architecture by stochastic assessment of technical, reliability, and economic risks. A propellant depot thermal model was developed to analyze the effectiveness of various thermal management systems, determine their optimal configuration, quantify the uncertainties in the system models, and stochastically compute the performance feasibility of the propellant depot system. Probabilistic cost analysis captured the uncertainty in the development cost of propellant depots and the fluctuation of commercial launch prices, and, along with the cost of launch failures, provided a metric for determining economic feasibility. Probabilistic reliability assessments using the launch schedule, launch reliability, and architecture requirements of each phase of the mission established launch success feasibility. Finally, an integrated stochastic optimization was performed to determine the feasibility of the exploration architecture. The final product of this research is an evaluation of propellant depots and commercial launch services as a practical method to achieving economic sustainability for human space exploration. A method for architecture feasibility assessment is demonstrated using stochastic system metrics and applied in the evaluation of technical, economic, and reliability feasibility of orbital propellant depots and commercial launch based exploration architectures. The results of the analysis showed the propellant depots based architectures to be technically feasible using current commercial launch vehicles, economically feasible for having a program budget less than $4 billion per year, and have launch reliability approaching the best single launch vehicle, Delta IV, with the use of redundant vehicles. These results serve to provide recommendations on the use of propellant depots in exploration architectures to the Moon, Near Earth Objects, Mars, and beyond.

SVOM est une mission spatiale franco-chinoise qui sera lancée à la fin de l’année 2021. Son objectif est d’étudier les sursauts gamma et autres sources transitoires du ciel X et gamma. Les sursauts gamma sont des explosions cosmiques brèves et très énergétiques permettant leurs détections à des distances extrêmes. Ils apparaissent de manière aléatoire sur tout le ciel et émettent de la radiation dans une large gamme de longueurs d’ondes, allant de l’émission en infrarouge jusqu’aux rayons gamma. SVOM, qui évoluera en orbite basse autour de la Terre, sera composé de quatre instruments, sensibles du domaine visible aux rayons gamma, et sera couplé à des télescopes situés sur Terre qui effectueront des observations complémentaires dans les longueurs d’ondes allant du visible à de l’infrarouge. Le travail que je présente dans cette thèse est basé sur l’étude des performances du télescope MXT, dont l’optique est inspirée du principe de fonctionnement des “yeux des langoustes”. Elle sera mise en place pour la première fois dans le cadre de télescopes X, nécessitant donc de comprendre la réponse de cette optique. MXT est chargé d’observer, la contrepartie qui suit les sursauts gamma, dite émission rémanente, dans la gamme des rayons X entre 0,2 et 10 keV. Il joue un rôle clé dans la localisation précise de ces sources astrophysiques afin de transmettre, en temps réel, leurs positions aux télescopes situés au sol, qui observeront à leur tour, rapidement et précisément, le phénomène. Au cours de mon travail de thèse, j’ai mis en place un simulateur d’observation de MXT qui m’a permis d’estimer et d’étudier les performances attendues de l’instrument au cours de la mission. J’ai également développé des algorithmes de localisation qui seront implémentés à bord du satellite. Ceux-ci m’ont ensuite permis de tester les capacités de localisation de MXT à partir d’une base de données des rémanences de sursauts gamma et de montrer que 50% de ces rémanences seront localisées plus précisément que la minute d’arc. J’ai enfin appliqué une partie de mes modélisations numériques dans le cas de sources d’ondes gravitationnelles afin d’évaluer la détection des contreparties X d’étoiles à neutrons binaires. / SVOM is a Sino-French space mission to be launched at the end of 2021. Its objective is the study of gamma-ray bursts (GRBs) and other transient high energy sources. These GRBs are very powerful cosmic explosions that can be detected at extreme distances. They appear randomly on all the sky and emit radiation in a wide wavelength range, from the infrared emission to gamma rays. SVOM space mission will shed new light on the physical phenomena associated to GRBs by detecting and observing them in real time over a wide energy range. The satellite, which will be injected on a low Earth orbit, will carry four instruments sensitive from the visible to the gamma-ray domain. Ground based telescopes will complement the space borne ones and will allow for follow-up observations from the visible to the infrared band. The MXT instrument, whose optics are based on the “lobster eyes” principle, will observe GRBs soft X-rays counterparts (afterglows) between 0.2 and 10 keV. This optics will be used for the first time for an X-ray telescope which means to characterize this optics. MXT will play a key role in the localization of these astrophysical sources that will be transmitted, in real time, to ground based instruments allowing for fast and precise observations. During my thesis, I developed an MXT observation simulator in order to predict the performances of the instrument during the mission. I also developed localization algorithms to be implemented on board the SVOM satellite and made use of the state of the art knowledge about X-ray afterglows in order to predict the localization capabilities of MXT. I demonstrated thaht 50% of these afterglows will be localized with a better precision than the arc-minute. I finally applied my simulation tools in the case of gravitational wave sources and, in particular, to assess the capabilities of MXT to observe bright X-ray counterparts of binary neutron star mergers.

Ce travail a comme objectif principal de vérifier s’il est possible de faire de la science avec les observations d’objets étendus qui seront réalisées par la mission spatiale Gaia. Cette mission, l’un des plus ambitieux projets de l’Astronomie moderne,observera plus d’un milliard d’objets dans tout le ciel avec des précisions inédites, fournissant des données astrométriques, photométriques et spectroscopiques. Naturellement, en fonction de sa priorité astrométrique, Gaia a été optimisé pour l’étude d’objets ponctuels. Néanmoins, diverses sources associées à des émissions étendues seront observées. Ces émissions peuvent avoir une origine intrinsèque, telles que les galaxies, ou extrinsèque, telles que les projections d’objets distincts sur la même ligne de visée, et présenteront probablement de solutions astrométriques moins bonnes.Pour étudier ces émissions, leurs images bidimensionnelles doivent être analysées.Néanmoins, comme Gaia ne produit pas de telles données, nous avons commencé ce travail en vérifiant si à partir de ses observations unidimensionnelles il serait possible de reconstruire des images 2D d’objets dans tout le ciel.Nous avons ainsi estimé la quantité de cas sujets à la présence d’émissions étendues extrinsèques, et nous avons présenté une méthode que nous avons développée pour analyser leurs images reconstruites. Nous avons montré que l’utilisation de cette méthode permettra d’étendre le catalogue final de façon fiable à des millions de sources ponctuelles dont beaucoup dépasseront la magnitude limite de l’instrument.D’un autre coté, dans le cas d’émissions intrinsèques, nous avons premièrement obtenu une estimation supérieure du nombre de cas que Gaia pourra observer. Nous avons alors vérifié qu’après les reconstructions d’images, les codes que nous avons développés permettront de classifier morphologiquement des millions de galaxies dans les types précoce/tardif et elliptique/spirale/irrégulière. Nous avons de plus présenté une méthode que nous avons développée pour réaliser la décomposition bulbe/disque directement à partir des observations unidimensionnelles de Gaia de façon complètement automatique.Finalement nous avons conclu qu’il est possible d’utiliser beaucoup de ces données qui pourraient être ignorées pour faire de la science. Et que le fait de les exploiter permettra aussi bien la détection de millions d’objets qui dépassent la limite de magnitude de Gaia, que de mener des études sur la morphologie de millions de galaxies dont les structures ne peuvent être révélées qu’à partir de l’espace ou au moyen d’optique adaptative, augmentant un peu plus les horizons de cette mission déjà immense. / The main objective of this work is to determine whether it is possible to do science from the observations of extended objects that will be performed by the Gaia space mission. One of the most ambitious projects of modern Astronomy, this mission will observe more than one billion objects through out the sky, thus providing astrometric, photometric and spectroscopic data with unprecedented precision. Naturally, Gaia has been optimized for the study of point-like sources due to its astrometrical priority. Nevertheless, many sources associated with extended emission will be observed. The origins of these extended sources can be either intrinsic, such as galaxies, or extrinsic, such as projections of objects in the same line of sight. In both cases, these sources will have less than optimal astrometric solutions.In order to study those emissions, their two-dimensional images will be analyzed. Nonetheless, since Gaia will not acquire such images, we begin this work by checking whether it will be possible to reconstruct images anywhere in the sky from the satellite’s one-dimensional observations.Consequently, we, on the one hand, estimate the number of cases which will be subjected to the extrinsic extended emissions, present a method which we developed to analyze the reconstructed images by segregating the different sources and show that the adoption of this method will allow extending the catalogue reliably by millions of point sources, many of which are beyond the limiting magnitude of the instrument. On the other hand, regarding intrinsic extended emissions, we first obtain an upper limit estimate for the number of cases which Gaia will be able to observe ; then,we verify that the combination of image reconstructions and the use of the codes introduced here in will allow performing the morphological classification of millions of galaxies in early/late types and elliptical/spiral/irregular classes. Afterward,we present a method which we developed to decompose those galaxies into their bulge/disk components directly from the one-dimensional Gaia data in a completely automatic way. Finally, we conclude that it is possible to harness the data of many of the observations that might other wise be ignored to do science. Saving these data will allow the detection of millions of objects beyond Gaia’s limiting magnitude and the study of the morphology of millions of galaxies whose structures can only be probed from space or through the adoption of adaptive optics, thus somewhat expanding the horizons of this already comprehensive mission.

Le rayonnement du Fond Diffus Cosmologique est une source riche et propre d’informations cosmologiques. L’étude du CMB au cours des dernières décennies a conduit à la mise en place d’un modèle standard pour la cosmologie et a permis de mesurer précisément ses principaux paramètres. Il a également transformé le domaine, en le basant davantage sur les données observationnelles et les approches numériques et statistiques.A l’heure actuelle, l’inflation est le principal paradigme décrivant les premiers moments de notre Univers. Elle prédit la génération de fluctuations de la densité de matière primordiale et des ondes gravitationnelles. Le signal de polarisation du CMB porte la signature de ces ondes gravitationnelles sous la forme de modes-B primordiaux. Une future génération de missions spatiale d’observation de la polarisation du CMB est bien adaptée à l’observation de cette signature de l’inflation.Cette thèse se concentre sur l’optimisation d’une future mission spatiale CMB qui observera le signal en modes-B pour atteindre une sensibilité de r = 0,001. Plus précisément, j’étudie la stratégie d’observation et l’impact des effets systématiques sur la qualité de la mesure de polarisation / The Cosmic Microwave Background radiation is a rich and clean source of Cosmological information. Study of the CMB over the past few decades has led to the establishment of a “Standard Model” for Cosmology and constrained many of its principal parameters. It hasalso transformed the field into a highly data-driven domain.Currently, Inflation is the leading paradigm describing the earliest moments of our Universe. It predicts the generation of primordial matter density fluctuations and gravitational waves. The CMB polarisation carries the signature of these gravitational waves in the form of primordial “B-modes”. A future generation of CMB polarisation space mission is well suited to observe this signature of Inflation.This thesis focuses on optimising a future CMB space mission that will observe the B-modesignal for reaching a sensitivity of r = 0.001. Specifically, I study the optimisation of the scanning strategy and the impact of systematics on the quality of polarisation measurement

No description available.