RT Generic
T1 Analysis and implementation of gravity field models for planets and asteroids
A1 García Pardo, Diego
AB Gravitational models are an essential tool to develop, simulate and predictthe behaviour of satellites, asteroids and other bodies of celestial nature.The accuracy of these models is of critical importance in surveillance, orbitdetermination and propagation.In the following pages, it will be presented two different models to study theeffect of gravity fields produced by both Planets and Asteroids.The reader must always note the importance of improving the results obtained by means of classical gravitational theories as modern society dependence in man-made space satellites is constantly growing, implying a directapplication in the industrial and academic fields. For example, Rummelexpects that the data retrieved by GRACE and GOCE missions will help tomodel with even higher precision the gravity levels as well as time variationsdue to tidal effects (both fluid and solid tides). The models here presentedtry to average this effects and to predict accurately the gravity vector fieldnear Earth but always neglecting time variations of the gravitational field.These models have been prototyped in MatLab and implemented in C programming languages. MatLab may be used for preliminary results as well asfor data analysis and interpretation. Mathematically speaking, these modelscover wide numerical ranges of magnitude that can lead to overow or underflow. Not in vane, big effort has been devoted to normalize the magnitude ofthe data used in calculations as well as special care in function evaluations.Also, MatLab parallel toolbox allows to perform easily parallel calculationwithout extra-effort.The implementation of such algorithms has already been a matter of concernas the algorithms have to be evaluated as fast as possible. The polyhedronalgorithm that will be presented later can be highly parallelized and hardwaremay make the difference rather than software. For example in [2] it canbe found a performance analysis comparing single-threaded implementationwith massively parallelized algorithm in CUDA GPU.The theories presented are based on classical Newton's laws but are intendedto improve the predictions of Newton's law of universal gravitation. However it is not the scope of this report to introduce relativistic effects as thevariations in the results as it will be shown are below the uncertainty level of the predictions done with the available data. Neither atmospheric drag norsolar radiation pressure have been modelled as they depend on the shape ofthe body. Only gravitational forces are studied.
YR 2014
FD 2014-06-21
LK https://hdl.handle.net/10016/22981
UL https://hdl.handle.net/10016/22981
LA eng
DS e-Archivo
RD 27 may. 2024