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.

Orbital Elements Evolution Due to a Perturbing Body in an Inclined Elliptical Orbit

Rahoma, W.A The Korean Space Science Society 2014 Journal of Astronomy and Space Sciences Vol.31 No.3

This paper intends to highlight the effect of the third-body in an inclined orbit on a spacecraft orbiting the primary mass. To achieve this goal, a new origin of coordinate is introduced in the primary and the X-axis toward the node of the spacecraft. The disturbing function is expanded up to the second order using Legendre polynomials. A double-averaged analytical model is exploited to produce the evolutions of mean orbital elements as smooth curves.

Orbital Elements Evolution Due to a Perturbing Body in an Inclined Elliptical Orbit

W. A. Rahoma 한국우주과학회 2014 Journal of Astronomy and Space Sciences Vol.31 No.3

This paper intends to highlight the effect of the third-body in an inclined orbit on a spacecraft orbiting the primary mass. To achieve this goal, a new origin of coordinate is introduced in the primary and the X-axis toward the node of the spacecraft. The disturbing function is expanded up to the second order using Legendre polynomials. A double-averaged analytical model is exploited to produce the evolutions of mean orbital elements as smooth curves.

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.

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

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.

Prognostic Value of Prepro-Gastrin Releasing Peptide in Lung Cancer Patients; NCI-Prospective Study

Shafik, Nevine F,Rahoma, M,Elshimy, Reham AA,El kasem, Fatma M Abou Asian Pacific Journal of Cancer Prevention 2016 Asian Pacific journal of cancer prevention Vol.17 No.12

Background: Prior series investigated the expression of prepro-gastrin releasing peptide (prepro-GRP) in the peripheral blood of lung cancer patients. Our aim was to assess any prepro-GRP role as a prognostic factor for small cell lung cancer (SCLC) and NSCLC and correlations with clinical presentation and treatment outcome. Methods: A prospective study was conducted during the time period from the beginning of January 2012 till the end of January 2014. Prepro-GRP expression was analysed using a nested RT-PCR assay in peripheral blood of 62 untreated lung cancer patients attending the National Cancer Institute (NCI), Cairo University, and 30 age and sex matched healthy volunteers. Results: Among the 62 lung cancer cases, there were 24 (38.7%) SCLC, and 38 (61.3%) NSCLC (10 squamous cell carcinomas, 12 adenocarcinomas, 11 large cell carcinomas, 4 undifferentiated carcinomas, and 1 adenosquamous carcinoma). Twenty six patients (41.9%) were prepro-GRP positive. Prepro-GRP expression was higher (58.3%) among SCLC patients compared to NSCLC (squamous cell carcinoma (15.4%), large cell carcinoma (36.4%), and adenocarcinoma (25%)). Mean OS among prepro-GRP negative cases was longer than that among preprogastrin positive cases (17.6 vs 14.9 months). The mean PFS durations among preprogastrin negative versus positive cases were 7.7 vs 4.6 months (p= 0.041). No difference in response to chemotherapy was identified between the groups (p=0.983). Conclusion: Prepro-GRP is suggested to be a useful prognostic marker for lung cancer patients, especially with the fast- growing, bad prognostic SCLC type. More studies should aim at detailed understanding of the mechanisms of prepro-GRP action and its use in monitoring the response to treatment in a larger cohort.

Frozen Orbits Construction for a Lunar Solar Sail

Khattab, Elamira Hend,Radwan, Mohamed,Rahoma, Walid Ali The Korean Space Science Society 2020 Journal of Astronomy and Space Sciences Vol.37 No.1

Frozen orbit is an attractive option for orbital design owing to its characteristics (its argument of pericenter and eccentricity are kept constant on an average). Solar sails are attractive solutions for massive and expensive missions. However, the solar radiation pressure effect represents an additional force on the solar sail that may greatly affect its orbital behavior in the long run. Thus, this force must be included as a perturbation force in the dynamical model for more accuracy. This study shows the calculations of initial conditions for a lunar solar sail frozen orbit. The disturbing function of the problem was developed to include the lunar gravitational field that is characterized by uneven mass distribution, third body perturbation, and the effect of solar radiation. An averaging technique was used to reduce the dynamical problem to a long period system. Lagrange planetary equations were utilized to formulate the rate of change of the argument of pericenter and eccentricity. Using the reduced system, frozen orbits for the Moon sail orbiter were constructed. The resulting frozen orbits are shown by two 3Dsurface (semi-major, eccentricity, inclination) figures. To simplify the analysis, we showed inclination-eccentricity contours for different values of semi-major axis, argument of pericenter, and values of sail lightness number.

Comparative Study on Bone Marrow-Versus Adipose-Derived Stem Cells on Regeneration and Re-Innervation of Skeletal Muscle Injury in Wistar Rats

Moussa Manal H.,Hamam Ghada G.,Abd Elaziz Asmaa E.,Rahoma Marwa A.,Abd El Samad Abeer A.,El-Waseef Dalia A. A.,Hegazy Mohamed A. 한국조직공학과 재생의학회 2020 조직공학과 재생의학 Vol.17 No.6

Background: Skeletal muscle injuries are frequent clinical challenges due to associated fibrosis and disability. Regenerative medicine is an emerging promising strategy for such cases. The aim of this study was to compare between the effects of bone marrow-mesenchymal stem cells (BM-MSCs) versus adipose tissue stromal cells (ADSCs) on regeneration and re-innervation of skeletal muscle laceration injury in Wistar rats at different time intervals. Methods: Six young male rats were used as a source of allogenic MSCs. Eighty-four adult female rats were divided into: Group I (control), Group II (Untreated Laceration): right gluteal muscle was lacerated and left for spontaneous healing, Group III (BM-MSCs): right gluteal muscle was lacerated with concomitant local intramuscular injection of 1 × 106 BM-MSCs in the lacerated muscle, Group IV (ADSCs): right gluteal muscle was lacerated with concomitant local intramuscular injection of 1 × 106 ADSCs in lacerated muscle. Rats were sacrificed after one, two and eight weeks. Muscles were processed to prepare sections stained with H&E, Mallory’s trichrome and immune-histochemical staining (neurofilament light chain). Results: A significant increase in collagen fibers and failure of re-innervation were noticed in untreated laceration group. BM-MSCs-treated groups showed regeneration of muscle fibers but with increased collagen fibers. Meanwhile, ADSCs showed better regenerative effects evidenced by significant increase in the number of myotubes and significant decrease in collagen deposition. Re-innervation was noticed in MSCs-injected muscles after 8 weeks of laceration. Conclusion: Both BM-MSCs and ADSCs improved regeneration of skeletal muscle laceration injury at short- and long-term durations. However, fibrosis was less in ADSCs-treated rats. Effective re-innervation of injured muscles occurred only at the long-term duration.

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.