Vázquez Valenzuela, RafaelMontilla García, José ManuelMalaver Jambrina, Antonio2022-12-192022-12-192022Malaver Jambrina, A. (2022). Analysis of perturbation effects in precise prediction of Low Earth Orbits. (Trabajo Fin de Grado Inédito). Universidad de Sevilla, Sevilla.https://hdl.handle.net/11441/140635Tras analizar el problema de los dos cuerpos y revisar en profundidad las distintas perturbaciones a las que están sometidos los satélites, se explica la herramienta Orekit. Esta permite el cálculo de la órbita de los satélites afectados bajo diferentes tipos de perturbaciones. Mediante Orekit se realiza un extenso análisis abordando las fuerzas más importantes que pueden afectar a satélites en LEO y GEO, para posteriormente pasar a analizar datos reales de satélites proporcionados por la agencia espacial europea en formato OEM. Con estos datos se diseña un propagador que permita predecir con alta precisión la posición y velocidad de los satélites Sentinel-1A/B y Sentinel-2A/B y finalmente se extraen las conclusiones y se proponen futuras mejoras.The objective of this project is to develop an accurate, efficient propagator for Low Earth Orbit satellites designed and launched by the European Space Agency. Predicting where an object will be after several hours since the last time we measured its position is crucial in order to prevent accidents with other satellites during the time lapse we can not track the satellite’s position and direction of movement. This need resulted in this project, in which the analysis of different kind of perturbations is made in order to decide which ones we should take into account and which ones are disposables. Perturbations can be understood as the forces that disturb the classical Keplerian orbit of orbiting objects. The four main forces that must be taken into account are the non-spherical body’s gravity, the third-body perturbations, the solar-radiation pressure and the atmospheric drag, being the last one the most important in LEO. Other kind of perturbations, such as tides or the precession of Earth’s axis, are discussed throughout this project. To perform the computations to predict the position and velocity of the satellites under study, the tool Orekit is used. This low-level space dynamic library written in Java can be integrated into Matlab, and offers a wide scope when studying space dynamics. This tool is the base of this project, and it is used to analyse the effect that different kind of perturbations have in LEO and GEO satellites. Since it was released as an open source in 2008, its popularity grew exponentially due to the precision that this tool allows. In this project its library is presented, as well as the different uses that this tool can have. The data of the satellites is provided by ESA in the form of Orbit Ephemeris Messages, which are used to specify the position and velocity of a single object at one or multiple epochs. The OEMs format is presented in this project, along with several examples of different versions of the OEMs. In order to design a precise propagator, a comparison between several perturbation models offered by Orekit’s library is carried out. These models are compared with one another to decide which one behaves better when propagating the orbit of the satellites studied. The propagator designed to propagate the orbits with high precision is presented, along with the results obtained for the Sentinel-1 and Sentinel-2 classes.application/pdf98 p.engAttribution-NonCommercial-NoDerivatives 4.0 Internacionalhttp://creativecommons.org/licenses/by-nc-nd/4.0/info:eu-repo/semantics/bachelorThesisinfo:eu-repo/semantics/openAccess