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Papers by JOSE MARIA GAMBI FERNANDEZ

Cema Working Papers Serie Documentos De Trabajo, 2005

Abstract—The purpose of this paper is to show that the equations for relative motions derived fro... more Abstract—The purpose of this paper is to show that the equations for relative motions derived from the two systems of post-Newtonian equations presented here, allow to increase the acquisition, pointing and tracking accuracy when compared to the Newtonian equations aimed to describe free-space laser communications between Low Earth Orbit (LEO) satellites, so as between LEO and Medium Earth Orbit (MEO), and Geostationary Earth Orbit (GEO) satellites. The equations discussed in this work are similar, but not equivalent to those proposed for space debris removal, i. e. in the context of spacebased systems to throw middle size LEO debris objects into the atmosphere via laser ablation. In fact, the present equations are computationally much more affordable because the aim is now less demanding, and so they result from subtractions within each postNewtonian system here provided.

International Journal of Aerospace Engineering, 2019

Two systems of Earth-centered inertial Newtonian orbital equations for a spherical Earth and thre... more Two systems of Earth-centered inertial Newtonian orbital equations for a spherical Earth and three systems of post-Newtonian nonlinear equations, derived from the second post-Newtonian approximation to the Earth Schwarzschild field, are used to carry out a performance analysis of a numerical procedure based on the Dormand-Prince method for initial value problems in ordinary differential equations. This procedure provides preliminary post-Newtonian corrections to the Newtonian trajectories of middle-size space objects with respect to space-based acquisition, pointing, and tracking laser systems, and it turns out to be highly efficient. In fact, we can show that running the standard adaptive ode45 MATLAB routine with the absolute and relative tolerance, TOLa = 10−16 and TOLr = 10−13, respectively, provides corrections that are final within the eclipses caused by the Earth and close to final during the noneclipse phases. These corrections should be taken into account to increase the po...

Photonics, 2021

In this paper, we introduce a computational procedure that enables autonomous LEO laser trackers ... more In this paper, we introduce a computational procedure that enables autonomous LEO laser trackers endowed with INSs to increase the current accuracy when shooting at middle distant medium-size LEO debris targets. The code is designed for the trackers to throw the targets into the atmosphere by means of ablations. In case that the targets are eclipsed to the trackers by the Earth, the motions of the trackers and targets are modeled by equations that contain post-Newtonian terms accounting for the curvature of space. Otherwise, when the approaching targets become visible for the trackers, we additionally use more accurate equations, which allow to account for the local bending of the laser beams aimed at the targets. We observe that under certain circumstances the correct shooting configurations that allow to safely and efficiently shoot down the targets, differ from the current estimations by distances that may be larger than the size of many targets. In short, this procedure enables ...

The equations of motion derived in this paper are aimed to determine according to the post-Newton... more The equations of motion derived in this paper are aimed to determine according to the post-Newtonian framework the relative motion of Earth satellites with respect to inertial guided space Acquisition, Pointing and Tracking systems. The equations are suitable for satellites that are even far from the systems. The tool used to derive them is Synge’s world-function for the Earth surrounding space. Hence the equations are written in terms of the quasi-Cartesian coordinates tied to the systems. Key–Words: Earth satellites, Intersatellite laser links, Acquisition, Pointing and Tracking systems, Earth postNewtonian framework

Aerospace Science and Technology, 2004

This paper addresses the optimal computation in terms of fuel consumption of the sequentially req... more This paper addresses the optimal computation in terms of fuel consumption of the sequentially required tangential correction manoeuvres to control geostationary satellites within the longitude band. In fact, by using optimal control techniques, the Sun pointing perigee strategy (which only determines the best time of the day for the tangential manoeuvres) is formulated as a nonlinear programming problem with inequality constraints so that the proposed approach provides an optimal way to determine the remaining parameters for the station keeping, i.e., the time interval between successive corrections and the value for the eccentricity control to totally optimize the computation. Furthermore, by minimizing a cost function derived for the total manoeuvres sizes required in a year, a numerical simulation is performed to illustrate this approach. The computation shows how geostationary mission lifetimes may be extended up to half a year or more.

Metodos De Dinamica Orbital Y Rotacional Iv Jornadas De Trabajo En Mecanica Celeste La Manga 20 22 De Septiembre 2002 Isbn 84 8371 326 8 Pags 55 62, 2002

Información del artículo A numerical simulator for the station keeping of geostationary satellites.

Xv Jornadas Luso Espanholas De Matematica Universidade De Evora 3 a 7 De Septembro De 1990 Vol 5 1991 Pags 293 297, 1991

Xv Jornadas Luso Espanholas De Matematica Universidade De Evora 3 a 7 De Septembro De 1990 Vol 5 1991 Pags 275 280, 1991