The Effects of Moon’s Uneven Mass Distribution on the Critical Inclinations of a Lunar Orbiter

Walid A. Rahoma,Fawzy A. Abd El-Salam 한국우주과학회 2014 Journal of Astronomy and Space Sciences Vol.31 No.4

The uneven mass distribution of the Moon highly perturbs the lunar spacecrafts. This uneven mass distribution leads to peculiar dynamical features of the lunar orbiters. The critical inclination is the value of inclination which keeps the deviation of the argument of pericentre from the initial values to be zero. Considerable investigations have been performed for critical inclination when the gravity field is assumed to be symmetric around the equator, namely for oblate gravity field to which Earth’s satellites are most likely to be subjected. But in the case of a lunar orbiter, the gravity field of mass distribution is rather asymmetric, that is, sectorial, and tesseral, harmonic coefficients are big enough so they can’t be neglected. In the present work, the effects of the first sectorial and tesseral harmonic coefficients in addition to the first zonal harmonic coefficients on the critical inclination of a lunar artificial satellite are investigated. The study is carried out using the Hamiltonian framework. The Hamiltonian of the problem is cconstructed and the short periodic terms are eliminated using Delaunay canonical variables. Considering the above perturbations, numerical simulations for a hypothetical lunar orbiter are presented. Finally, this study reveals that the critical inclination is quite different from the critical inclination of traditional sense and/or even has multiple solutions. Consequently, different families of critical inclination are obtained and analyzed.

Investigating Exoplanet Orbital Evolution Around Binary Star Systems with Mass Loss

Walid A. Rahoma 한국우주과학회 2016 Journal of Astronomy and Space Sciences Vol.33 No.4

A planet revolving around binary star system is a familiar system. Studies of these systems are important because they provide precise knowledge of planet formation and orbit evolution. In this study, a method to determine the evolution of an exoplanet revolving around a binary star system using different rates of stellar mass loss will be introduced. Using a hierarchical triple body system, in which the outer body can be moved with the center of mass of the inner binary star as a two-body problem, the long period evolution of the exoplanet orbit is determined depending on a Hamiltonian formulation. The model is simulated by numerical integrations of the Hamiltonian equations for the system over a long time. As a conclusion, the behavior of the planet orbital elements is quite affected by the rate of the mass loss from the accompanying binary star.

The Effects of Moon's Uneven Mass Distribution on the Critical Inclinations of a Lunar Orbiter

Rahoma, Walid A.,Abd El-Salam, Fawzy A. The Korean Space Science Society 2014 Journal of Astronomy and Space Sciences Vol.31 No.4

The uneven mass distribution of the Moon highly perturbs the lunar spacecrafts. This uneven mass distribution leads to peculiar dynamical features of the lunar orbiters. The critical inclination is the value of inclination which keeps the deviation of the argument of pericentre from the initial values to be zero. Considerable investigations have been performed for critical inclination when the gravity field is assumed to be symmetric around the equator, namely for oblate gravity field to which Earth's satellites are most likely to be subjected. But in the case of a lunar orbiter, the gravity field of mass distribution is rather asymmetric, that is, sectorial, and tesseral, harmonic coefficients are big enough so they can't be neglected. In the present work, the effects of the first sectorial and tesseral harmonic coefficients in addition to the first zonal harmonic coefficients on the critical inclination of a lunar artificial satellite are investigated. The study is carried out using the Hamiltonian framework. The Hamiltonian of the problem is cconstructed and the short periodic terms are eliminated using Delaunay canonical variables. Considering the above perturbations, numerical simulations for a hypothetical lunar orbiter are presented. Finally, this study reveals that the critical inclination is quite different from the critical inclination of traditional sense and/or even has multiple solutions. Consequently, different families of critical inclination are obtained and analyzed.

The Effects of Moon’s Uneven Mass Distribution on the Critical Inclinations of a Lunar Orbite

Walid A. Rahoma,Fawzy A. Abd El-Salam 한국우주과학회 2014 Journal of Astronomy and Space Sciences Vol.31 No.4

The uneven mass distribution of the Moon highly perturbs the lunar spacecrafts. This uneven mass distribution leadsto peculiar dynamical features of the lunar orbiters. The critical inclination is the value of inclination which keeps thedeviation of the argument of pericentre from the initial values to be zero. Considerable investigations have been performedfor critical inclination when the gravity field is assumed to be symmetric around the equator, namely for oblate gravityfield to which Earth’s satellites are most likely to be subjected. But in the case of a lunar orbiter, the gravity field of massdistribution is rather asymmetric, that is, sectorial, and tesseral, harmonic coefficients are big enough so they can’t beneglected. In the present work, the effects of the first sectorial and tesseral harmonic coefficients in addition to the firstzonal harmonic coefficients on the critical inclination of a lunar artificial satellite are investigated. The study is carriedout using the Hamiltonian framework. The Hamiltonian of the problem is cconstructed and the short periodic termsare eliminated using Delaunay canonical variables. Considering the above perturbations, numerical simulations for ahypothetical lunar orbiter are presented. Finally, this study reveals that the critical inclination is quite different from thecritical inclination of traditional sense and/or even has multiple solutions. Consequently, different families of criticalinclination are obtained and analyzed.

Resonance Capture for a Mercurian Orbiter in the Vicinity of Sun

Khattab, Elamira Hend,El-Salam, Fawzy Ahmed Abd,Rahoma, Walid A. The Korean Space Science Society 2021 Journal of astronomy and space sciences Vol.38 No.2

In this work, the problem of resonance caused by some gravitational potentials due to Mercury and a third body, namely the Sun, together with some non-gravitational perturbations, specifically coronal mass ejections and solar wind in addition to radiation pressure, are investigated. Some simplifying assumptions without loss of accuracy are employed. The considered force model is constructed. Then the Delaunay canonical set is introduced. The Hamiltonian of the problem is obtained then it is expressed in terms of the Deluanay canonical set. The Hamiltonian is re-ordered to adopt it to the perturbation technique used to solve the problem. The Lie transform method is surveyed. The Hamiltonian is doubly averaged. The resonance capture is investigated. Finally, some numerical simulations are illustrated and are analyzed. Many resonant inclinations are revealed.

Resonance Capture for a Mercurian Orbiter in the Vicinity of Sun

Khattab, Elamira Hend,El-Salam, Fawzy Ahmed Abd,Rahoma, Walid A. The Korean Space Science Society 2021 Journal of Astronomy and Space Sciences Vol.38 No.2

In this work, the problem of resonance caused by some gravitational potentials due to Mercury and a third body, namely the Sun, together with some non-gravitational perturbations, specifically coronal mass ejections and solar wind in addition to radiation pressure, are investigated. Some simplifying assumptions without loss of accuracy are employed. The considered force model is constructed. Then the Delaunay canonical set is introduced. The Hamiltonian of the problem is obtained then it is expressed in terms of the Deluanay canonical set. The Hamiltonian is re-ordered to adopt it to the perturbation technique used to solve the problem. The Lie transform method is surveyed. The Hamiltonian is doubly averaged. The resonance capture is investigated. Finally, some numerical simulations are illustrated and are analyzed. Many resonant inclinations are revealed.