AAS 95-332

Optimal Design and Orbital Control of Satellite Constellations for Global Coverage

G. B. Palmerini, Universita degli Studi di Roma 'La Sapienza

Abstract

Orbital perturbations have to be considered on the basis of their differential effects for global coverage constellations, since a global shift of the constellation around the globe is allowed. Differential effects concern satellites on different planes, because the (usually short) orbital period makes the behavior homogeneous for the satellites in the same plane. Attention is primarily focused on the third body effect. The precession around the lunar orbit pole depends on the value of the angles between the constellation planes and the Moon orbital plane. The motion of the Moon settles a dissymmetry between the positions of the constellation orbital planes. The nodes could be chosen in order to minimize different behavior among the planes. Also non gravitational perturbations cause different behavior among several orbital planes. Especially in highly-inclined, quasi-heliosynchronous cases, satellites experience different amount of solar radiation pressure and air drag. Dynamical background gives the chance to design the orbital control strategy. Maneuvers can be optimized with respect to minimal propellant consumption and maximization of the services, in terms of visibility time and covered area. Other constraint to be considered is the uniform propellant consumption among all the satellites.