Eva Tresaco

Analytical Model to Find Frozen Orbits for a Lunar Orbiter

Analytical theories based on Lie-Deprit transforms are used to obtain families of periodic orbits for the problem of an orbiter around the moon. Low and moderately high orbit models are analyzed. Equilibria of the normalized equations of motion provide the representation of a global portrait of families of frozen orbits depending on values of the inclination, eccentricity, and semimajor axis. By means of the inverse transformation it is possible to refine the initial conditions for frozen orbits of a simplified model, and these initial conditions may be used as starters of numerical continuation methods when more complex models are considered.

Perturbações orbitais sobre uma vela solar

ela Solar e um tipo de propulsao que utiliza a pressao de radiacao solar para gerar aceleracao, ganha impulso ao refletir os fotons. Em teoria, esses fotons irao transferir a sua energia para as velas solares, fazendo com que a nave se movimente. No presente momento as velas solares estao ganhando atencao da comunidade cientifica ja que oferecem a possibilidade de missoes de longa distancia e baixo custo, o que seria impossivel para qualquer outro tipo de nave espacial convencional. Neste trabalho, e analisado a dinamica de uma vela solar em torno de um planeta. Sao feitas aplicacoes para uma vela solar em torno do planeta Mercurio levando em conta a sua distribuicao nao uniforme de massa (J2 , J3 e C22 ), a perturbacao do terceiro corpo (PTC) e a pressao de radiacao solar (PRS) para diferentes altitudes. Encontramos orbitas congeladas para altitudes em torno de 300 km, 500 km e 1000 km que sao os valores preditos para a missao BepiColombo que esta prevista para visitar Mercurio nos proximos anos.

Analysis of frozen orbits for solar sails

The use of propellantless propulsion systems like solar sails in the recent days has attracted the interest for scientific missions. The influence of the radiation pressure on the sail creates an additional force to the dynamics of the problem, and this force which must be taken into account since it may modify greatly the behavior of the orbits. In this communication, we will see how the radiation pressure affects frozen orbits around a planet when the spacecraft is a solar sail, thus on the spacecraft the acting forces are the gravitational field of the planet, the gravitational perturbation due to the Sun (third body effect) and the radiation pressure on the sail.

Numerical analysis of periodic solutions and bifurcations in the planetary annulus problem

This paper discusses the dynamics of particles orbiting planetary rings under a general central potential. Starting with the mathematical description of the dynamical system, we analyze the motion of a particle with infinitesimal mass as attracted by a central body surrounded by a homogeneous circular annular disk. Throughout the paper we carry out an analytic search of the most relevant equilibria solutions and, based on that, we investigate numerically the stability matrix of the system to find stability inequalities. In this way, we describe the in-plane and out-of-plane motion by means of the numerical continuation of a wide number of uni-parametric families of planar and spatial periodic orbits. We present a description of the main families of periodic orbits encountered, their bifurcations and linear stability. With the aim of reproducing a more realistic scenario, we analyse different mass proportions between the annulus and the central body, we consider an oblate planet and we also include a composition of rings in the dynamical model.

Gravitational Potential of a Massive Disk. Dynamics Around an Annular Disk

This article studies the main features of the dynamics around an annular disk. The first part addresses the difficulties finding a usable expression of the gravitational potential of a massive disk that will be used later on to define the differential equations of motion of our dynamical system.