Orbital evolution and maneuvers around non-spherical bodies / Evolução orbital e manobras em torno de corpos não-esféricos

AUTOR(ES)
DATA DE PUBLICAÇÃO

2006

RESUMO

In the last years several asteroids had their shapes identified using images from space probes or through the indirect radar data determination. In a general way, these asteroids have forms quite different from spherical. Conventional spherical harmonic representations of the gravitational potential of such bodies require expansions of high degree and order, which are numerically difficult to obtain. The polyhedral method is well suited to evaluate the gravitational field of an irregularly shaped body such as asteroids, comet nucleus and small planetary satellites. If complete coverage of the surface can be obtained, a polyhedral model of the body can be constructed. The purpose of the present work is to determine an analytical form to represent the potential around an irregular shaped body; to obtain a description of the possible orbital evolutions of a space vehicle that travels around a celestial body with those characteristics; and, finally, to find solutions for the problem of orbital maneuvers with minimum consumption of fuel. The results consist of sets of analytical expressions that give the potential due to different two-dimensional geometric forms that were implemented and tested. In the group of two-dimensional bodies it is included a study of the space of phase of the orbit in order to verify the stability or instability areas and the collision areas. This study is made through Poincaré surface of section technique. It is also used the polyhedral method to study the gravitational potential of a spherical and non spherical three-dimensional bodies (a unity radius sphere, a prolate and an oblate ellipsoids with different values of semi axis). The dynamics of the orbit of a test particle around of such bodies is studied. In general, when the particle is far from the sphere, its position returns to the initial point after a keplerian orbital period. On the other hand, when the particle gets close to its surface, the effect of its polyhedral form shows shortperiodic variations in the semimajor axis and eccentricity of the orbit. The results showed that the orbits close to the ellipsoids become eccentric and precess due the effects of its potential. With these results it can be verified that the polyhedral form of the object does work very well and this method is efficient for the trajectory study. The work generates fundamental theoretical knowledge that it can be applied in irregular bodies with more complex forms, such as the asteroids.

ASSUNTO(S)

engenharia e tecnologia espacial space tecnology and engineering Órbitas de transferência ellipsoids poliedros polyedrons análise de trajetória potential transfer orbits elipsóides potencial trajectory analysis

ACESSO AO ARTIGO

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