Analisando a possibilidade de um anel ao redor de um satélite

Abstract

On November 26 th, 2005, Rhea, one of Saturn's moons, is found by Cassini spacecraft approximately at 5.105 km from Saturn. Observations in situ reveal that electrons are depleted in the moon's vicinity. However, Rhea is considered massive enough to retain a thin atmosphere. Assumption was that the atmosphere of Rhea was not composed exclusively of gas, its likely contains solid material that can absorb magnetospheric particles. According to Jones et al. (2008), these particles were in a speci c position so that at the moment of observation the electrons could not be detected. In opposition to this idea there is a group, Tiscareno et al. 2010, Cornell University Library, that underwent intensive search for any material that might be orbiting Rhea using Cassini images, however the could not identify any. Second recommendation made by American researchers and other countries, and accepted by the National Board of Research the Cassini Equinox Mission will continue in orbit around Saturn until 2016.The probe will perform several maneuvers with high inclination to delve into the main ring system, and then enter in Saturn's atmosphere and collide with planet. This research is of great importance because until today no rings were found orbiting satellites. The goal of this work is to analyze the orbital evolution of a set of particles around Rhea disturbance of Saturn, J2 e J4 and check results by the numerical simulations and the possibility of a stable ring orbiting Rhea.

Em 26 de Novembro de 2005, Rhea, mais uma lua de Saturno, e encontrada pela sonda Cassini a aproximadamente 5 105 km de Saturno. Observa c~oes \in locorealizadas pela sonda revelaram que os el etrons energ eticos estariam esgotados nas imedia c~oes da lua. No entanto, Rhea e considerada massiva o su ciente para manter uma na atmosfera. A suposi c~ao na epoca, foi a de que a atmosfera de Rhea n~ao era composta exclusivamente de g as, que conteria material s olido, part culas da magnetosfera. Segundo Jones et al. (2008), essas part culas estariam numa determinada posi c~ao, de forma que no momento da observa c~ao impossibilitou a observa c~ao dos el etrons. Em oposi c~ao a essa ideia, h a um grupo de pesquisa (Tiscareno et al. 2010, Cornell University Library) que realizou intensa busca por qualquer material que pudesse estar orbitando Rhea, utilizando imagens da Cassini, n~ao obtendo qualquer evid encia. Segundo recomenda c~ao feita por pesquisadores norte-americanos e de outros pa ses, e aceita pelo Conselho Nacional de Pesquisa (National Research Council), a Cassini Equinox Mission continuar a em orbita ao redor de Saturno at e 2016, o que possibilitar a mais observa c~oes sobre Rhea e seus poss veis an eis. A sonda executar a v arias manobras com alta inclina c~ao at e mergulhar no sistema principal de an eis, para ent~ao entrar na atmosfera de Saturno e colidir com o planeta. A presente pesquisa e de grande importancia pois at e hoje n~ao foram encontrados an eis orbitando sat elites. O objetivo deste trabalho e analisar a evolu c~ao orbital de um conjunto de part culas ao redor de Rhea sob a perturba c~ao de Saturno, J2 e J4 e veri- car pelas simula c~oes num ericas e resultados a possibilidade de um anel est avel orbitando Rhea.