This thesis will focus on the performance of angles only initial orbit determi- nation (IOD) methods on observational data of low Earth orbit (LEO) CubeSats. Using data obtained by Lockheed Martin’s Space Object Tracking (SpOT) facil- ity, four methods: Gauss, Double-R, Gooding and Assumed Circular, will use different amounts of orbital arc to determine which methods perform the best in the short arc regime of less than 10 degrees of orbital arc. Once the best method for estimating the orbit is determined, there will be analysis on whether these IOD methods are accurate enough to predict a secondary observation session. Finally non-linear regression will be performed to determine if the error metrics follow a predictable trend based on how much orbital arc is seen by the observer. It was determined that above a certain amount of orbital arc, angles only IOD methods can reliably predict a secondary observation session to facilitate more observations. Below 4 degrees of orbital arc, which is around 60 seconds of ob- serving time for LEO objects, none of the methods were able to reliably predict a secondary observation session. The Assumed Circular method was the best method for observing LEO CubeSats because it forces the IOD solution to be circular, which limits the error in the shape of the orbit as the amount of orbital arc decreases. Finally, many metrics follow an exponential trend when compared to the orbital arc. Thus, the amount of orbital arc seen is a strong predictor for the accuracy of the angles only IOD solutions.

The structure and payload of a CubeSat flight experiment that investigates the performance of particle dampers in a micro-gravity environment was designed, built, and tested, and will provide on orbit data for model validation and improved performance predictions for space applications of particle damping. A 3-D solid model of the integrated CubeSat structure and payload was created satisfying all constraints from CubeSat and the System Dynamics Department at Northrop Grumman Aerospace Systems. The model was verified using commercially available Finite Element Analysis software (FEA), and a prototype structure part was fabricated. The prototype was tested and verified the FEA. A complete subassembly ready for flight was manufactured as an engineering unit and tested to space qualification loads of both launch vibration and thermal vacuum. Two additional units were contracted out for manufactured to serve as the flight unit and backup, and are currently ready for launch.

This dissertation discusses research that focuses on understanding transneptunian objects (TNOs) using a variety of techniques and approaches. In Chapter 1, I introduce the main concepts used throughout this dissertation and discuss the current understanding of the transneptunian region. In Chapter 2, I discuss my efforts to understand how Neptune's late stages of migration affect the Haumea family, the only known collisional family in the transneptunian region. Using advanced simulations of Neptune migration, I find that the Haumea family can plausibly form before the termination of giant planet migration and show that this extensively mixes the family. The simplest explanation for the formation of Haumea and its family is a slow disruption of a large, primordial binary system. In Chapter 3, I examine the detectability of non-Keplerian effects in the mutual orbits of transneptunian binaries. I find non-Keplerian effects are common, with 20% of TNBs best explained by a non-Keplerian orbit. I also demonstrate that one of the components of TNB (66652) Borasisi-Pabu is a contact binary. In Chapter 4, I examine the non-Keplerian orbits of Hi'iaka and Namaka, the satellites of Haumea, showing that they are strongly affected by both inter-satellite gravitational interactions and precession caused by Haumea's nonspherical gravitational field. Future observations of the Haumea system, combined with non-Keplerian fitting, will sensitively probe Haumea's interior. Lastly, in Chapter 5, I explore the mutual orbits of Cold Classical TNO binaries using non-Keplerian orbit fitting. Out of a sample of 18 binaries, 6 have significantly non-Keplerian orbits, allowing detailed characterization of their system architecture. I find that 3 of these systems are best explained as hierarchical systems, while the remaining 3 are consistent with precession due to the Sun's gravitational influence. The hierarchical systems I find strongly support the streaming instability theory of planetesimal formation.

The system of sparse gridpoints was used to propagate uncertainty forward in time through orbital mechanics simulations. Propagation of initial uncertainty through a nonlinear dynamic model is examined in regards to the uncertainty of orbit estimation. The necessary underlying mechanics of orbital mechanics, probability, and nonlinear estimation theory are reviewed to allow greater understanding of the problem. The sparse grid method itself and its implementation is covered in detail, along with the necessary properties and how to best it to a given problem based on inputs and desired outputs. Three test cases were run in the form of a restricted two-body problem, a perturbed two-body problem, and a three-body problem in which the orbiting body is positioned at a Lagrange point. It is shown that the sparse grid method shows sufficient accuracy for all mean calculations in the given problems and that higher accuracy levels allow for accurate estimation of higher moments such as the covariance.

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<p> A model of two predators competing for the same prey also involving predation interaction between the two predators is considered. Coexistence in forms of equilibria and periodic orbits is obtained by using bifurcation and dynamical systems theory. Global dynamics is obtained by studying the survival functions and persistence is obtained by using a theorem of Freedman and Waltman. Finally, numerical results for a specific example demonstrate the above. A Hopf bifurcation at the interior equilibrium and its unstable periodic orbit are observed.</p> / Thesis / Master of Science (MSc)

Providing affordable Internet access to rural populations in large developing countries to aid economic and social progress, using various non-conventional techniques has been a topic of active research recently. The main obstacle in providing fiber-optic based terrestrial Internet links to remote villages is the cost involved in laying the cable network and disproportionately low rate of return on investment due to low density of paid users. The conventional alternative to this is providing Internet access using geostationary satellite links, which can prove commercially infeasible in predominantly cost-driven rural markets in developing economies like India or China due to high access cost per user. A low-cost derivative of the conventional satellite-based Internet access system can be developed by utilizing an aging geostationary satellite nearing the end of its active life, allowing it to enter an inclined geosynchronous orbit by limiting station keeping to only east-west maneuvers to save fuel. Eliminating the need for individual satellite receiver modules by using one centrally located earth station per village and providing last mile connectivity using Wi-Fi can further reduce the access cost per user. A Ku band system design for rural India based on this concept, using an Intelsat 906 satellite is proposed in this thesis. The path of the satellite and the tracking requirements at village stations are determined. Components required for various blocks of the system are defined. Modulation schemes, FEC, data rates, number of customers to be served, link availability and outage statistics are presented. Quantitative analysis using link budgets and ITU rain models are provided. An optimized system design and a commercial deployment model are suggested which show the system is economically feasible. / Master of Science

L'objet de cette thèse est l'étude de la structure symplectique des orbites coadjointes holomorphes, et de leurs projections.Une orbite coadjointe holomorphe O est une orbite coadjointe elliptique d'un groupe de Lie G réel semi-simple connexe non compact à centre fini provenant d'un espace symétrique hermitien G/K, telle que O puisse être naturellement munie d'une structure kählérienne G-invariante. Ces orbites coadjointes sont une généralisation de l'espace symétrique hermitien G/K.Dans cette thèse, nous prouvons que le symplectomorphisme de McDuff se généralise aux orbites coadjointes holomorphes, décrivant la structure symplectique de l'orbite O par le produit direct d'une orbite coadjointe compacte et d'un espace vectoriel symplectique. Ce symplectomorphisme est ensuite utilisé pour déterminer les équations de la projection de l'orbite O relative au sous-groupe compact maximal K de G, en faisant intervenir des résultats récents de Ressayre en Théorie Géométrique des Invariants. / This thesis studies the symplectic structure of holomorphic coadjoint orbits and the projection of such orbits.A holomorphic coadjoint orbit O is an elliptic coadjoint orbit which is endowed with a natural invariant Kählerian structure. These coadjoint orbits are defined for real semi-simple connected non compact Lie group G with finite center such that G/K is a Hermitian symmetric space, where K is a maximal compact subgroup of G. Holomorphic coadjoint orbits are a generalization of the Hermitian symmetric space G/K.In this thesis, we prove that the McDuff's symplectomorphism, available for Hermitian symmetric spaces, has an analogous for holomorphic coadjoint orbits. Then, using this symplectomorphism and recent GIT arguments from Ressayre, we compute the equations of the projection of the orbit O, relatively to the maximal compact subgroup K.