Dinâmica do sistema binário Plutão-Caronte

Pós-graduação em Física - FEG

Satélites estabilizados por rotação e torque de radiação solar direta

The aims of this work are to analyze the direct solar radiation pressure torque (TPRS) in the rotational motion of spin-stabilized artificial satellites, to numerically implement these solutions and to compare the results with real data of the Brazilian Satellite Data Collection – SCD1 and SCD2, supplied by INPE. The mathematical model for this torque is determined for a cylindrical satellite, and the components of this torque are determined in a fixed system in the satellite. An analytical solution for the spin motion equations is proposed, in which TPRSD does not affect the spin velocity of the satellite. Two approaches are adopted in the numerical implementation of the developed theory: the first one considers the proposed theory and the second introduces a variation in the spin velocity based on its real variation. The results obtained indicate that the solar radiation pressure torque has little influence in the right ascension and declination axis of rotation due to the small dimension of the satellite and altitude in which it is found. To better validate the application of the presented theory, the angular deviation of the spin axis and solar aspect angle were also analyzed. The comparison of the results of the approaches conducted with real data show good precision in the theory, which can be applied in the prediction of the rotational motion of the spin-stabilized artificial satellites, when others external torques are considered besides the direct solar radiation pressure torque

Projeto de um módulo condicionador de sinais a ser implementado no satélite universitário ITASAT

The Brazilian Environmental Data Collection System (Sistema Brasileiro de Coleta de Dados Ambientais - SBCDA) has been providing reliable information regarding the monitoring of the Brazil environment to INPE (Instituto Nacional de Pesquisas Espaciais) and many Non-governmental organizations (NGO). This system is composed of a large number of Data Collection Plataforms (DCP), in charge of sending local data signals to satellites. Then the satellites automatically redirect each signal to reception centers located at INPE. Nowadays the SBCDA has been operating under the control of three satellites. It is important to mention that two of these satellites have already expired their life span around ten years ago. A strategy to keep the SBCDA operational is to develop a low cost satellite that involves Brazilian Universities and Public Institutions. This graduation work aims to design and simulate a signal conditioning module that enables the collection of a satellite status data, and then sending it to an onboard computer

Utilização de técnicas de geoprocessamento para monitoramento de atividades de mineração ao longo de dutos: poliduto Rio de Janeiro/Minas Gerais

The transportation of oil through polyducts implies a concern related to safety and environmental impacts they may cause, especially when exposed to risks that affect their integrity. Among the various anthropogenic activities included in this scenario, mining can aggravate, increase the risks and degrade the environment. Since these polyducts go through significant extensions, remote sensing has great applicability as a tool for data acquisition. For this, change detection techniques were used to monitor mining activities in a defined study area in the state of Rio de Janeiro, along the duct ORBEL. The characterization of the study area and the mining activities were developed through bibliographical data. The satellite images processing and the application of change detection technique were performed in two scenes for the years 2002 and 2010. The growth in the mining area was about 6.67 times and it was possible to identify types of extraction involved which can represent direct risks to the pipeline

Análise da estabilidade do movimento rotacional de satélites artificiais com quatérnions e sob a influência de torques externos

The aim of this work is to analyze the stability of the rotational motion’s artificial satellite using the Routh Hurwitz Algorithm (CRH) and the quaternions to describe the satellite’s attitude. This algorithm allows the investigation of the stability of the motion using the coefficients of the characteristic equation associated with the equation of the rotational motion in the linear form. The equations of the rotational motion are given by the four cinematic equations for the quaternion and the three equations of Euler for the spin velocity’s components. In the Euler equations are included the components of the gravity gradient torque (TGG) and the solar radiation torque (TRS). The TGG is generated by the difference of the Earth gravity force direction and intensity actuating on each satellite mass element and it depends on the mass distribution and the form of the satellite. The TRS is created by changing of the linear momentum, which happens due to the interactions of solar photons with the satellite surface. The equilibrium points are gotten by the equation of rotational motion and the CRH is applied in the linear form of these equations. Simulations are developed for small and medium satellites, but the gotten equilibrium points are not stable by CRH. However, when some of the eigenvalues of the characteristic equation are analyzed, it is found some equilibrium points which can be pointed out as stables for an interval of the time, due to small magnitude of the real part of these eigenvalue

Recebimento de dados GNSS via Internet em RTCM 3 e conversão para RINEX utilizando a plataforma J2ME

Changes are occurring worldwide, including the area of positioning using Global Navigation Satellite Systems in mobile devices such as mobile phones or laptops. This is due to the great improvement and availability of Internet services to these mobile devices. The accuracy and speed of data transmission for these devices makes the technology of sending / receiving data via an internet targeted for optimization. The optimization could allow obtaining, in real-time, coordinates (latitude, longitude and altitude) of suitable quality for users of GPS (Global Positioning System) devices that have wireless Internet access, such as those used to control the eet, locomotion, navigation, agriculture, etc. . The use of the protocol NTRIP (Networked Transport of RTCM via Internet Protocol) in GPS applications is growing every day. Applications are available in C, which creates an opportunity for development with a focus on multiplatform environments. In this context, we propose an application, implemented in a multiplatform environment and the use of NTRIP, able to run on a mobile device for receiving GNSS data

Analisando a possibilidade de um anel ao redor de um satélite

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.

Captura gravitacional de pequenos corpos por arrasto em um gás modelado usando equações hidrodinâmicas

In this work we have developed an apparatus in order to study the capture of asteroids by planets surrounded by a gas envelope during y-by, to do this we have brought an innovation by using a hydrodynamical gas. We began such project by studying particles trajectories with a code based on the analytical gas. After being used to this model we have started a process to elaborate a code which uses the gas in a numerical way. The hydrodynamical gas is described by equations which are not solved analytically. Therefore, it was used an algorithm able to model the gas by keeping all information of the gas in cells. Thus we have made a code to read such cell`s information and then to solve all calculations. Once this process is done, the program inform us all date about the simulated trajectories

Modelos dinâmicos simplificados, para verificação do comportamento de rede de satélites amarrados por cabos flexíveis, usando-se o método explícito das diferenças finitas

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Estudos sobre as defasagens de Prometeu e Pandora

Pós-graduação em Física - FEG

Estudo de manobras evasivas com perturbações orbitais

Pós-graduação em Física - FEG

Dinâmica da fragmentação florestal e conflito de uso do solo ao longo da rede de drenagem do município de Lençóis Paulista - SP

Pós-graduação em Agronomia (Energia na Agricultura) - FCA

Estudos de acoplamento spin-órbita em dinâmica do sistema solar

Pós-graduação em Física - FEG

Prospecção mineral de alvos potenciais à ocorrência de enriquecimento supergênico de níquel no Greenstone belt do Morro do Ferro

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Potencial gravitacional lunar

We know that the orbit of a lunar satellite, and consequently its orbital lifetime is mainly inuenced by the gravitational field of the Moon, Earth and Sun. In this text we study the Lunar gravitational potential and its influence on the gravitational field. We adapted a program in order to map the Moon gravitational field. To that end it was necessary to develop a program that allows the simulation and mapping the lunar full potential. Our program was based on the program developed by Hélio Kuga, and adapted to our case (Moon). We used the model proposed by Konopliv et al. 2001, we proposed various degree and order expansions of spherical harmonics that served us to compare and validate our program