De Cássia Domingos, Rita [UNESP]De Moraes, Rodolpho Vilhena [UNESP]De Almeida Prado, Antonio Fernando Bertachini [UNESP]2014-05-272014-05-272008-12-01Advances in the Astronautical Sciences, v. 129 PART 3, p. 2639-2652.0065-3438http://hdl.handle.net/11449/70861In the present work it is presented a semi-analytical and a numerical study of the perturbation caused in a spacecraft by a third body using a double averaged analytical model with the disturbing function expanded in Legendre polynomials up to the second-order. The important reason for this procedure is to eliminate the terms due to the short time periodic motion of the spacecraft and to show smooth curves for the evolution of the mean orbital elements for a long time period. The aim of this study is to calculate the effect of lunar perturbations on the orbits of spacecrafts that are traveling around the Earth. It is presented an analysis of the stability of a near-circular orbit and a study to know under which conditions this orbit remains near-circular. A study of the equatorial orbits is also performed.2639-2652engAnalytical modelsDisturbing functionsElliptic orbitsEquatorial orbitsLegendre polynomialsNear-circular orbitsNumerical studiesOrbital elementsPeriodic motionsSecond ordersSemi-analyticalSmooth curvesThird bodiesThird-body perturbationsTime periodsAstrophysicsDynamicsSpacecraftOrbitsTrabalho apresentado em eventoWOS:000257272902039Acesso aberto2-s2.0-6034910290977409171447574100000-0003-1289-8332