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

Syfte: Syftet med denna undersökning är att göra en komparativ studie mellan Sverige-och global aktiefonder för att vidare analysera vilka aktiefonder som ger högst avkastning. Metod: Uppsatsen bygger på en statistisk analys vilket sekundärdata ligger till grund för våra beräkningar. Genom tillämpning av kvantifierbar hård data där bland annat historiska aktiekurser ingår, så har en kvantitativ studie använts. Befintliga teorier och modeller har tillämpats. Slutsats: Studien visar i stort sett att högre risk ger en högre avkastning. Under period 1 presterade Latin Amerika fonderna bäst varefter Sverige fonder presterade bättre under period 2. Dessa marknader kan vara väldigt oberoende av varandra och tenderar därmed inte att följa varandras kursutveckingen. Slutsatsen är då att en investering i olika geografiska placeringar diversifierar risken mer. Exempelvis en investering i en svensk fond och en latin amerika fond.