Analysis of Perturbation incidence in the calculation of trajectories in Ephemeris Model
The main goal of this thesis is to deepen the understanding of the influence that the various perturbations exert on the trajectory calculations performed by the JPL ephemeris model to provide high-fidelity ephemeris in support of spacecraft navigation and other activities related to Solar System bo...
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| Tipo de recurso: | tesis de maestría |
| Fecha de publicación: | 2020 |
| País: | España |
| Institución: | Universitat Politècnica de Catalunya (UPC) |
| Repositorio: | UPCommons. Portal del coneixement obert de la UPC |
| Idioma: | inglés |
| OAI Identifier: | oai:upcommons.upc.edu:2117/177939 |
| Acceso en línea: | https://hdl.handle.net/2117/177939 |
| Access Level: | acceso abierto |
| Palabra clave: | Numerical analysis Orbital mechanics Perturbation theory Special Perturbation Techniques N-Body Problem Numerical methods MatLab Anàlisi numèrica Mecànica orbital Pertorbació (Matemàtica) Àrees temàtiques de la UPC::Aeronàutica i espai |
| Sumario: | The main goal of this thesis is to deepen the understanding of the influence that the various perturbations exert on the trajectory calculations performed by the JPL ephemeris model to provide high-fidelity ephemeris in support of spacecraft navigation and other activities related to Solar System bodies. One of the drawbacks behind such a complex method are the large machine-oriented technical requirements it has in terms of time and computational cost. The algorithm that integrates the full dynamical model of the N-Body differential equations of motion requires a continuous update of the dynamical states (positions and velocities) of a large number of bodies for each new integration step, regardless of the perturbation model applied or the nature and diversity of the sources of perturbations other than those gravitational considered. This work focuses especially to the gravitational implications of interplanetary trajectories, based on the fact that within its main and longest phase (the cruise phase) a spacecraft is essentially affected by a multi-body attraction. A procedure has been conducted to build a tool that, applied to any given interplanetary trajectory, has the ability of predicting which gravitational perturbations are not relevant and can thus be neglected without a significant loss of accuracy. Validation tests based on the BepiColombo interplanetary ephemeris trajectory planned mission proved that no significant differences are found when comparing the discrepancies exhibited by a numerical propagation of its initial conditions with the N-Body differential equations of motion, including all planetary perturbations or only those indicated as relevant by the developed 2D maps. A comparison is also carried out between two of the most popular special perturbation techniques, Cowell and Encke, which demonstrated that round off errors take its toll even working in double precision and showed that Encke’s method performs much better for interplanetary trajectories where there is a large difference in forces between the central dominant body and the perturbing bodies. Finally, a simple debugging test carried out by MatLab showed that both time and computational resources (amount of data) are sensibly reduced by not considering those negligible bodies suggested by the application of maps and tests. Thus, this result offer the possibility to save time both in the access and in the download of ephemeris data from the platform while avoiding loading times to create large data matrices in the workspace. |
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