The Experts below are selected from a list of 297 Experts worldwide ranked by ideXlab platform
W. Tsoka - One of the best experts on this subject based on the ideXlab platform.
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On the secular recession of the Earth-Moon System as an azimuthal gravitational phenomenon
Astrophysics and Space Science, 2015Co-Authors: G. G. Nyambuya, T. Makwanya, B. A. Tuturu, W. TsokaAbstract:We here apply the ASTG-model to the observed secular trend in the mean Sun-(Earth-Moon) and Earth-Moon distances thereby providing an alternative explanation as to what the cause of this secular trend may be. Within the margins of observational error; for the semi-major axis rate of the Earth-Moon System, in agreement with observations (of Standish and Kurtz, Proceedings IAU Colloquium, IAU, pp. 163–179, Cambridge University Press, Cambridge, 2005 ), we obtain a value of about +(5.10±0.10) cm/yr. The ASTG-model predicts orbital drift as being a result of the orbital inclination and the Solar mass loss rate. The Newtonian gravitational constant G is assumed to be an absolute time constant. Krasinsky and Brumberg (Celest. Mech. Dyn. Astron. 90(3–4):267–288, 2004 ); Standish and Kurtz ( 2005 ) reported for the Earth-Moon System, an orbital recession from the Sun of about +(15.00±4.00) cm/yr and +(7.00±2.00) cm/yr respectively; while Williams et al. (Phys. Rev. Lett. 93:261101, 2004 ); Williams and Boggs (Proceedings of 16th International Workshop on Laser Ranging, Space Research Centre, Polish Academy of Sciences, Poland, 2009 ), Williams et al. (Planet. Sci. 3(1):2, 2014 ) report for the Moon, a semi-major axis rate of about +(38.08±0.04) mm/yr from the Earth. The predictions of the ASTG-model for the Earth-Moon System agrees very well with those the findings of Standish and Kurtz ( 2005 ), Krasinsky and Brumberg ( 2004 ). The lost orbital angular momentum for the Earth-Moon System—which we here hypothesize to be gained as spin by the two body Earth-Moon System; this lost angular momentum accounts very well for the observed Lunar drift, therefore, one can safely say that the ASTG-model does to a reasonable degree of accuracy predict the observed Lunar semi-major axis rate of about +(38.08±0.04) mm/yr from the Earth.
Jingshi Tang - One of the best experts on this subject based on the ideXlab platform.
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On Utilization of Solar Sails in Triangular Libration Point Missions in the Earth-Moon System
Transactions of The Japan Society for Aeronautical and Space Sciences Space Technology Japan, 2020Co-Authors: Jingshi TangAbstract:In the real solar System, due to various perturbations, the triangular libration points of the Earth-Moon System are unstable. However, there are quasi-periodic orbits around them. These orbits show mild instability. Due to the instability, orbit control is necessary for the spacecrafts around these points. In the paper, solar sails were taken to fulfill the control. Numerical simulations were made in the Earth-Moon System. The results showed that taking the surface of the solar sail as the control parameter can achieve better results. Triangular Libration points in the Earth-Moon System have fixed configurations with the earth and the moon. This geometrical property is ideal for some space missions. For example, relay stations can be put around them. Spacecrafts can also be sent to these points for deep space observations. Along with the observations on earth, better observation data can be obtained. Besides this, these points are ideal potential candidates for space VLBI observations. In the restricted three-body problem of the Earth-Moon System, the mass ratio μ is smaller than Routh’s critical value μ1=0.03852…. They are linearly stable in the restricted three-body problem 1) . However, in the real solar System, various perturbations (mainly the gravitational perturbations from the sun) change their dynamical properties and these points are no longer stable anymore. Nevertheless, quasi-periodic orbits staying around them can be found. These orbits show mild instability. Due to their instability, orbit control is necessary for the spacecrafts moving on these orbits. Solar sails can produce long-lasting thrust and do not require any fuels. It’s an ideal choice for space missions. They were taken to fulfill the orbit control in this paper. The magnitude and direction of the thrust produced by the solar sail are coupled, and the force is always directed away from the sun. This is one shortcoming of the solar sails. Due to this property, instead of the tight control strategy, we took a loose one. This strategy needs a pre-determined nominal orbit. A quasi-periodic orbit around the triangular libration points was chosen as the nominal orbit. Two sets of different control variables were used. One set is the surface of the solar sail, and the other one is the normal direction angles of the solar sail. Numerical simulations were done in the Earth-Moon System. The results showed that taking the surface of the solar sail as the control variable is better. During the lifetime of the spacecraft, it may be shadowed from the sun by the earth or the moon. The solar sail is of no use when the spacecraft is in the shadow. In order to avoid the shadows, the initial epoch of the nominal orbit is carefully chosen. Since the inclination angle between the moon’s and the sun’s orbit planes is small, the z amplitude motion of the nominal orbit is chosen to be large to avoid the shadows too. For a short time mission, these steps can avoid the shadows. For a long time mission, the spacecraft will encounter the shadows anyway. At the end of the paper, a discussion of this case was made. For the shadows in the paper, cylindrical model was considered.
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Autonomous Orbit Determination of Satellites Around Triangular Libration Points in the Earth–Moon System
Proceedings of the 28th Conference of Spacecraft TT&C Technology in China, 2017Co-Authors: Jingshi TangAbstract:Recently, people are proposing to build a deep space navigation constellation in the earth–moon System which utilizes libration points of the Earth–Moon System. In a recent paper of the authors, two special stable orbits called as dynamical substitutes (DSs) around each triangular libration point (TLPs) are given in the real earth–moon System which is perturbed by the Sun. Due to their stability, orbits around the DSs are ideal for locating the navigation satellites. Theoretically, the orbits of the navigation satellites can be autonomously determined by only using the inter-satellite range data. As a result, no support from the ground stations is needed, and the navigation constellation can autonomously perform their roles in space. The current work is devoted to this problem, i.e., the autonomous orbit determination (AOD) between satellites locating around the DSs which are circling around the TLPs. Studies show that in order to obtain good AOD results, the data length should not be too short, and the satellite should have motion component perpendicular to the Moon’s orbital plane. The current study can be used when deploying the navigation constellation in the earth–moon System.
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Transfer to the Collinear Libration Point L3 in the Sun-Earth+Moon System
2007Co-Authors: Jingshi TangAbstract:The collinear libration point L3 of the sun-earth+moon System is an ideal place for some space missions. Although there has been a great amount of work concerning the applications of the other two collinear libration points L1 and L2, little work has been done about the point L3. In this paper, the dynamics of the libration points was briefly introduced first. Then a way to transfer the spacecraft to the collinear libration point L3 via the invariant manifolds of the other two collinear libration points was proposed. Theoretical works under the model of circular restricted three-body problem were done. For the sun-earth+moon System, this model is a good approximation. The results obtained are useful when a transfer trajectory under the real solar System is designed.
G. G. Nyambuya - One of the best experts on this subject based on the ideXlab platform.
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On the Secular Recession of the Earth-Moon System as an Azimuthal Gravitational Phenomenon (II)
viXra, 2016Co-Authors: G. G. Nyambuya, T. Makwanya, B. A. Tuturu, TsokaAbstract:We here apply the ASTG-model to the observed anomalous secular trend in the mean Sun-(Earth-Moon) and Earth-Moon distances. For the recession of the Earth-Moon System, in agreement with observation, we obtain a recession of about 11.20 ± 0.20 cm/yr. The ASTG-model predicts orbital drift as being a result of the orbital inclination and the Solar mass loss rate. The Newtonian gravitational constant G is assumed to be absolute time constant. Standish (2005); Krasinsky and Brumberg (2004) reported for the Earth-Moon System, an orbital recession from the Sun of about (15.00 ± 4.00) cm/yr; while Williams et al. (2004); Williams and Boggs (2009); Williams et al. (2014) report for the Moon, an orbital recession of about 38.00 mm/yr from the Earth. The predictions of the ASTG-model for the Earth-Moon System agrees very well with those the findings of Standish (2005); Krasinsky and Brumberg (2004). The lost orbital angular momen-tum for the Earth-Moon System – which we here hypothesize to be gained as spin by the two body Earth-Moon System; this lost angular momentum accounts very well for the observed lunar drift, therefore, one can safely safely say that the ASTG-model does to a reasonable degree of accuracy predict the observed lunar drift of about 38.00 mm/yr from the Earth.
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On the secular recession of the Earth-Moon System as an azimuthal gravitational phenomenon
Astrophysics and Space Science, 2015Co-Authors: G. G. Nyambuya, T. Makwanya, B. A. Tuturu, W. TsokaAbstract:We here apply the ASTG-model to the observed secular trend in the mean Sun-(Earth-Moon) and Earth-Moon distances thereby providing an alternative explanation as to what the cause of this secular trend may be. Within the margins of observational error; for the semi-major axis rate of the Earth-Moon System, in agreement with observations (of Standish and Kurtz, Proceedings IAU Colloquium, IAU, pp. 163–179, Cambridge University Press, Cambridge, 2005 ), we obtain a value of about +(5.10±0.10) cm/yr. The ASTG-model predicts orbital drift as being a result of the orbital inclination and the Solar mass loss rate. The Newtonian gravitational constant G is assumed to be an absolute time constant. Krasinsky and Brumberg (Celest. Mech. Dyn. Astron. 90(3–4):267–288, 2004 ); Standish and Kurtz ( 2005 ) reported for the Earth-Moon System, an orbital recession from the Sun of about +(15.00±4.00) cm/yr and +(7.00±2.00) cm/yr respectively; while Williams et al. (Phys. Rev. Lett. 93:261101, 2004 ); Williams and Boggs (Proceedings of 16th International Workshop on Laser Ranging, Space Research Centre, Polish Academy of Sciences, Poland, 2009 ), Williams et al. (Planet. Sci. 3(1):2, 2014 ) report for the Moon, a semi-major axis rate of about +(38.08±0.04) mm/yr from the Earth. The predictions of the ASTG-model for the Earth-Moon System agrees very well with those the findings of Standish and Kurtz ( 2005 ), Krasinsky and Brumberg ( 2004 ). The lost orbital angular momentum for the Earth-Moon System—which we here hypothesize to be gained as spin by the two body Earth-Moon System; this lost angular momentum accounts very well for the observed Lunar drift, therefore, one can safely say that the ASTG-model does to a reasonable degree of accuracy predict the observed Lunar semi-major axis rate of about +(38.08±0.04) mm/yr from the Earth.
T. Makwanya - One of the best experts on this subject based on the ideXlab platform.
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On the Secular Recession of the Earth-Moon System as an Azimuthal Gravitational Phenomenon (II)
viXra, 2016Co-Authors: G. G. Nyambuya, T. Makwanya, B. A. Tuturu, TsokaAbstract:We here apply the ASTG-model to the observed anomalous secular trend in the mean Sun-(Earth-Moon) and Earth-Moon distances. For the recession of the Earth-Moon System, in agreement with observation, we obtain a recession of about 11.20 ± 0.20 cm/yr. The ASTG-model predicts orbital drift as being a result of the orbital inclination and the Solar mass loss rate. The Newtonian gravitational constant G is assumed to be absolute time constant. Standish (2005); Krasinsky and Brumberg (2004) reported for the Earth-Moon System, an orbital recession from the Sun of about (15.00 ± 4.00) cm/yr; while Williams et al. (2004); Williams and Boggs (2009); Williams et al. (2014) report for the Moon, an orbital recession of about 38.00 mm/yr from the Earth. The predictions of the ASTG-model for the Earth-Moon System agrees very well with those the findings of Standish (2005); Krasinsky and Brumberg (2004). The lost orbital angular momen-tum for the Earth-Moon System – which we here hypothesize to be gained as spin by the two body Earth-Moon System; this lost angular momentum accounts very well for the observed lunar drift, therefore, one can safely safely say that the ASTG-model does to a reasonable degree of accuracy predict the observed lunar drift of about 38.00 mm/yr from the Earth.
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On the secular recession of the Earth-Moon System as an azimuthal gravitational phenomenon
Astrophysics and Space Science, 2015Co-Authors: G. G. Nyambuya, T. Makwanya, B. A. Tuturu, W. TsokaAbstract:We here apply the ASTG-model to the observed secular trend in the mean Sun-(Earth-Moon) and Earth-Moon distances thereby providing an alternative explanation as to what the cause of this secular trend may be. Within the margins of observational error; for the semi-major axis rate of the Earth-Moon System, in agreement with observations (of Standish and Kurtz, Proceedings IAU Colloquium, IAU, pp. 163–179, Cambridge University Press, Cambridge, 2005 ), we obtain a value of about +(5.10±0.10) cm/yr. The ASTG-model predicts orbital drift as being a result of the orbital inclination and the Solar mass loss rate. The Newtonian gravitational constant G is assumed to be an absolute time constant. Krasinsky and Brumberg (Celest. Mech. Dyn. Astron. 90(3–4):267–288, 2004 ); Standish and Kurtz ( 2005 ) reported for the Earth-Moon System, an orbital recession from the Sun of about +(15.00±4.00) cm/yr and +(7.00±2.00) cm/yr respectively; while Williams et al. (Phys. Rev. Lett. 93:261101, 2004 ); Williams and Boggs (Proceedings of 16th International Workshop on Laser Ranging, Space Research Centre, Polish Academy of Sciences, Poland, 2009 ), Williams et al. (Planet. Sci. 3(1):2, 2014 ) report for the Moon, a semi-major axis rate of about +(38.08±0.04) mm/yr from the Earth. The predictions of the ASTG-model for the Earth-Moon System agrees very well with those the findings of Standish and Kurtz ( 2005 ), Krasinsky and Brumberg ( 2004 ). The lost orbital angular momentum for the Earth-Moon System—which we here hypothesize to be gained as spin by the two body Earth-Moon System; this lost angular momentum accounts very well for the observed Lunar drift, therefore, one can safely say that the ASTG-model does to a reasonable degree of accuracy predict the observed Lunar semi-major axis rate of about +(38.08±0.04) mm/yr from the Earth.
B. A. Tuturu - One of the best experts on this subject based on the ideXlab platform.
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On the Secular Recession of the Earth-Moon System as an Azimuthal Gravitational Phenomenon (II)
viXra, 2016Co-Authors: G. G. Nyambuya, T. Makwanya, B. A. Tuturu, TsokaAbstract:We here apply the ASTG-model to the observed anomalous secular trend in the mean Sun-(Earth-Moon) and Earth-Moon distances. For the recession of the Earth-Moon System, in agreement with observation, we obtain a recession of about 11.20 ± 0.20 cm/yr. The ASTG-model predicts orbital drift as being a result of the orbital inclination and the Solar mass loss rate. The Newtonian gravitational constant G is assumed to be absolute time constant. Standish (2005); Krasinsky and Brumberg (2004) reported for the Earth-Moon System, an orbital recession from the Sun of about (15.00 ± 4.00) cm/yr; while Williams et al. (2004); Williams and Boggs (2009); Williams et al. (2014) report for the Moon, an orbital recession of about 38.00 mm/yr from the Earth. The predictions of the ASTG-model for the Earth-Moon System agrees very well with those the findings of Standish (2005); Krasinsky and Brumberg (2004). The lost orbital angular momen-tum for the Earth-Moon System – which we here hypothesize to be gained as spin by the two body Earth-Moon System; this lost angular momentum accounts very well for the observed lunar drift, therefore, one can safely safely say that the ASTG-model does to a reasonable degree of accuracy predict the observed lunar drift of about 38.00 mm/yr from the Earth.
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On the secular recession of the Earth-Moon System as an azimuthal gravitational phenomenon
Astrophysics and Space Science, 2015Co-Authors: G. G. Nyambuya, T. Makwanya, B. A. Tuturu, W. TsokaAbstract:We here apply the ASTG-model to the observed secular trend in the mean Sun-(Earth-Moon) and Earth-Moon distances thereby providing an alternative explanation as to what the cause of this secular trend may be. Within the margins of observational error; for the semi-major axis rate of the Earth-Moon System, in agreement with observations (of Standish and Kurtz, Proceedings IAU Colloquium, IAU, pp. 163–179, Cambridge University Press, Cambridge, 2005 ), we obtain a value of about +(5.10±0.10) cm/yr. The ASTG-model predicts orbital drift as being a result of the orbital inclination and the Solar mass loss rate. The Newtonian gravitational constant G is assumed to be an absolute time constant. Krasinsky and Brumberg (Celest. Mech. Dyn. Astron. 90(3–4):267–288, 2004 ); Standish and Kurtz ( 2005 ) reported for the Earth-Moon System, an orbital recession from the Sun of about +(15.00±4.00) cm/yr and +(7.00±2.00) cm/yr respectively; while Williams et al. (Phys. Rev. Lett. 93:261101, 2004 ); Williams and Boggs (Proceedings of 16th International Workshop on Laser Ranging, Space Research Centre, Polish Academy of Sciences, Poland, 2009 ), Williams et al. (Planet. Sci. 3(1):2, 2014 ) report for the Moon, a semi-major axis rate of about +(38.08±0.04) mm/yr from the Earth. The predictions of the ASTG-model for the Earth-Moon System agrees very well with those the findings of Standish and Kurtz ( 2005 ), Krasinsky and Brumberg ( 2004 ). The lost orbital angular momentum for the Earth-Moon System—which we here hypothesize to be gained as spin by the two body Earth-Moon System; this lost angular momentum accounts very well for the observed Lunar drift, therefore, one can safely say that the ASTG-model does to a reasonable degree of accuracy predict the observed Lunar semi-major axis rate of about +(38.08±0.04) mm/yr from the Earth.
