The Experts below are selected from a list of 309 Experts worldwide ranked by ideXlab platform
G Congedo - One of the best experts on this subject based on the ideXlab platform.
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space tests of the strong equivalence principle bepicolombo and the sun earth Lagrangian Points opportunity
International Journal of Modern Physics D, 2017Co-Authors: Fabrizio De Marchi, G CongedoAbstract:The validity of General Relativity (GR), after 100 years, is supported by solid experimental evidence. However, there is a lot of interest in pushing the limits of precision by other experiments. Here, we focus our attention on the equivalence principle (EP), in particular, the strong form. The results of ground experiments and Lunar Laser Ranging (LLR) have provided the best upper limit on the Nordtvedt parameter η that models deviations from the strong EP. Its uncertainty is currently σ[η] = 4.4 × 10−4. In the first part of this paper, we will describe the experiment, to measure η, that will be done by the future mission BepiColombo (BC). The expected precision on η is ≈ 10−5. In the second part, we will consider the ranging between the Earth and a spacecraft (SC) orbiting near the Sun–Earth Lagrangian Points to get an independent measurement of η. In this case, we forecast a constraint similar to that achieved by LLR.
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Space tests of the strong equivalence principle: BepiColombo and the Sun–Earth Lagrangian Points opportunity
International Journal of Modern Physics D, 2017Co-Authors: Fabrizio De Marchi, G CongedoAbstract:The validity of General Relativity (GR), after 100 years, is supported by solid experimental evidence. However, there is a lot of interest in pushing the limits of precision by other experiments. Here, we focus our attention on the equivalence principle (EP), in particular, the strong form. The results of ground experiments and Lunar Laser Ranging (LLR) have provided the best upper limit on the Nordtvedt parameter η that models deviations from the strong EP. Its uncertainty is currently σ[η] = 4.4 × 10−4. In the first part of this paper, we will describe the experiment, to measure η, that will be done by the future mission BepiColombo (BC). The expected precision on η is ≈ 10−5. In the second part, we will consider the ranging between the Earth and a spacecraft (SC) orbiting near the Sun–Earth Lagrangian Points to get an independent measurement of η. In this case, we forecast a constraint similar to that achieved by LLR.
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Space tests of the strong equivalence principle: BepiColombo and the Sun–Earth Lagrangian Points opportunity
International Journal of Modern Physics D, 2017Co-Authors: Fabrizio De Marchi, G CongedoAbstract:The validity of General Relativity (GR), after 100 years, is supported by solid experimental evidence. However, there is a lot of interest in pushing the limits of precision by other experiments. Here, we focus our attention on the equivalence principle (EP), in particular, the strong form. The results of ground experiments and Lunar Laser Ranging (LLR) have provided the best upper limit on the Nordtvedt parameter [Formula: see text] that models deviations from the strong EP. Its uncertainty is currently [Formula: see text]. In the first part of this paper, we will describe the experiment, to measure [Formula: see text], that will be done by the future mission BepiColombo (BC). The expected precision on [Formula: see text] is [Formula: see text]. In the second part, we will consider the ranging between the Earth and a spacecraft (SC) orbiting near the Sun–Earth Lagrangian Points to get an independent measurement of [Formula: see text]. In this case, we forecast a constraint similar to that achieved by LLR.
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space tests of the strong equivalence principle bepicolombo and the sun earth Lagrangian Points opportunity
arXiv: General Relativity and Quantum Cosmology, 2017Co-Authors: Fabrizio De Marchi, G CongedoAbstract:The validity of General Relativity, after 100 years, is supported by solid experimental evidence. However, there is a lot of interest in pushing the limits of precision by other experiments. Here we focus our attention on the equivalence principle, in particular the strong form. The results of ground experiments and lunar laser ranging have provided the best upper limit on the Nordtvedt parameter {\eta} that models deviations from the strong equivalence principle. Its uncertainty is currently {\sigma}[{\eta}] =4.4 $\times$ $10^{-4}$. In the first part of this paper we will describe the experiment, to measure {\eta}, that will be done by the future mission BepiColombo. The expected precision on {\eta} is $\approx$ $10^{-5}$. In the second part we will consider the ranging between the Earth and a spacecraft orbiting near the Sun-Earth Lagrangian Points to get an independent measurement of {\eta}. In this case, we forecast a constraint similar to that achieved by lunar laser ranging.
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testing the strong equivalence principle with spacecraft ranging towards the nearby Lagrangian Points
Physical Review D, 2016Co-Authors: G Congedo, Fabrizio De MarchiAbstract:General relativity is supported by great experimental evidence. Yet there is a lot of interest in precisely setting its limits with on going and future experiments. A question to answer is about the validity of the Strong Equivalence Principle. Ground experiments and Lunar Laser Ranging have provided the best upper limit on the Nordtvedt parameter $\sigma[\eta]=4.4\times 10^{-4}$. With the future planetary mission BepiColombo, this parameter will be further improved by at least an order of magnitude. In this paper we envisage yet another possible testing environment with spacecraft ranging towards the nearby Sun-Earth collinear Lagrangian Points. Neglecting errors in planetary masses and ephemerides, we forecast $\sigma[\eta]=6.4\,(2.0)\times10^{-4}$ (5 yr integration time) via ranging towards $L_1$ in a realistic (optimistic) scenario depending on current (future) range capabilities and knowledge of the Earth's ephemerides. A combined measurement, $L_1$+$L_2$, gives instead $4.8\,(1.7)\times10^{-4}$. In the optimistic scenario a single measurement of one year would be enough to reach $\approx3\times10^{-4}$. All figures are comparable with Lunar Laser Ranging, but worse than BepiColombo. Performances could be much improved if data were integrated over time and over the number of satellites flying around either of the two Lagrangian Points. We point out that some systematics (gravitational perturbations of other planets or figure effects) are much more in control compared to other experiments. We do not advocate a specific mission to constrain the Strong Equivalence Principle, but we do suggest analysing ranging data of present and future spacecrafts flying around $L_1$/$L_2$ (one key mission is, for instance, LISA Pathfinder). This spacecraft ranging would be a new and complementary probe to constrain the Strong Equivalence Principle in space.
M K Ammar - One of the best experts on this subject based on the ideXlab platform.
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the effect of solar radiation pressure on the Lagrangian Points in the elliptic restricted three body problem
Astrophysics and Space Science, 2008Co-Authors: M K AmmarAbstract:In this paper the effect of solar radiation pressure on the location and stability of the five Lagrangian Points is studied, within the frame of elliptic restricted three-body problem, where the primaries are the Sun and Jupiter acting on a particle of negligible mass. We found that the radiation pressure plays the rule of slightly reducing the effective mass of the Sun and changes the location of the Lagrangian Points. New formulas for the location of the collinear libration Points were derived. For large values of the force ratio β, we found that at β=0.12, the collinear point L3 is stable and some families of periodic orbits can be drawn around it.
O C Winter - One of the best experts on this subject based on the ideXlab platform.
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alternative transfer to the earth moon Lagrangian Points l4 and l5 using lunar gravity assist
Advances in Space Research, 2014Co-Authors: F J T Salazar, Elbert E N Macau, O C WinterAbstract:Abstract Lagrangian Points L4 and L5 lie at 60° ahead of and behind the Moon in its orbit with respect to the Earth. Each one of them is a third point of an equilateral triangle with the base of the line defined by those two bodies. These Lagrangian Points are stable for the Earth–Moon mass ratio. As so, these Lagrangian Points represent remarkable positions to host astronomical observatories or space stations. However, this same distance characteristic may be a challenge for periodic servicing mission. This paper studies elliptic trajectories from an Earth circular parking orbit to reach the Moon’s sphere of influence and apply a swing-by maneuver in order to re-direct the path of a spacecraft to a vicinity of the Lagrangian Points L4 and L5. Once the geocentric transfer orbit and the initial impulsive thrust have been determined, the goal is to establish the angle at which the geocentric trajectory crosses the lunar sphere of influence in such a way that when the spacecraft leaves the Moon’s gravitational field, its trajectory and velocity with respect to the Earth change in order to the spacecraft arrives at L4 and L5. In this work, the planar Circular Restricted Three Body Problem approximation is used and in order to avoid solving a two boundary problem, the patched-conic approximation is considered.
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dynamics of a spacecraft and normalization around Lagrangian Points in the neptune triton system
Advances in Space Research, 2008Co-Authors: T J Stuchi, T Yokoyama, A A Correa, R H Solorzano, Diogo M Sanchez, S M G Winter, O C WinterAbstract:Abstract The problem of a spacecraft orbiting the Neptune–Triton system is presented. The new ingredients in this restricted three body problem are the Neptune oblateness and the high inclined and retrograde motion of Triton. First we present some interesting simulations showing the role played by the oblateness on a Neptune’s satellite, disturbed by Triton. We also give an extensive numerical exploration in the case when the spacecraft orbits Triton, considering Sun, Neptune and its planetary oblateness as disturbers. In the plane a × I ( a = semi-major axis, I = inclination), we give a plot of the stable regions where the massless body can survive for thousand of years. Retrograde and direct orbits were considered and as usual, the region of stability is much more significant for the case of direct orbit of the spacecraft (Triton’s orbit is retrograde). Next we explore the dynamics in a vicinity of the Lagrangian Points. The Birkhoff normalization is constructed around L 2 , followed by its reduction to the center manifold. In this reduced dynamics, a convenient Poincare section shows the interplay of the Lyapunov and halo periodic orbits, Lissajous and quasi-halo tori as well as the stable and unstable manifolds of the planar Lyapunov orbit. To show the effect of the oblateness, the planar Lyapunov family emanating from the Lagrangian Points and three-dimensional halo orbits are obtained by the numerical continuation method.
Alessandra Celletti - One of the best experts on this subject based on the ideXlab platform.
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the effect of poynting robertson drag on the triangular Lagrangian Points
Icarus, 2015Co-Authors: Christoph Lhotka, Alessandra CellettiAbstract:Abstract We investigate the stability of motion close to the Lagrangian equilibrium Points L 4 and L 5 in the framework of the spatial, elliptic, restricted three-body problem, subject to the radial component of Poynting–Robertson drag. For this reason we develop a simplified resonant model, that is based on averaging theory, i.e. averaged over the mean anomaly of the perturbing planet. We find temporary stability of particles displaying a tadpole motion in the 1:1 resonance. From the linear stability study of the averaged simplified resonant model, we find that the time of temporary stability is proportional to β a 1 n 1 , where β is the ratio of the solar radiation over the gravitational force, and a 1 , n 1 are the semi-major axis and the mean motion of the perturbing planet, respectively. We extend previous results (Murray, C.D. [1994]. Icarus 112, 465–484) on the asymmetry of the stability indices of L 4 and L 5 to a more realistic force model. Our analytical results are supported by means of numerical simulations. We implement our study to Jupiter-like perturbing planets, that are also found in extra-solar planetary systems.
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The effect of Poynting–Robertson drag on the triangular Lagrangian Points
Icarus, 2015Co-Authors: Christoph Lhotka, Alessandra CellettiAbstract:Abstract We investigate the stability of motion close to the Lagrangian equilibrium Points L 4 and L 5 in the framework of the spatial, elliptic, restricted three-body problem, subject to the radial component of Poynting–Robertson drag. For this reason we develop a simplified resonant model, that is based on averaging theory, i.e. averaged over the mean anomaly of the perturbing planet. We find temporary stability of particles displaying a tadpole motion in the 1:1 resonance. From the linear stability study of the averaged simplified resonant model, we find that the time of temporary stability is proportional to β a 1 n 1 , where β is the ratio of the solar radiation over the gravitational force, and a 1 , n 1 are the semi-major axis and the mean motion of the perturbing planet, respectively. We extend previous results (Murray, C.D. [1994]. Icarus 112, 465–484) on the asymmetry of the stability indices of L 4 and L 5 to a more realistic force model. Our analytical results are supported by means of numerical simulations. We implement our study to Jupiter-like perturbing planets, that are also found in extra-solar planetary systems.
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on the stability of the Lagrangian Points in the spatial restricted problem of three bodies
Celestial Mechanics and Dynamical Astronomy, 1991Co-Authors: Alessandra Celletti, Antonio GiorgilliAbstract:The problem of stability of the Lagrangian equilibrium point of the circular restricted problem of three bodies is investigated in the light of Nekhoroshev-like theory. Looking for stability over a time interval of the order of the estimated age of the universe, we find a physically relevant stability region. An application of the method to the Sun-Jupiter and the Earth-Moon systems is made. Moreover, we try to compare the size of our stability region with that of the region where the Trojan asteroids are actually found; the result in such case is negative, thus leaving open the problem of the stability of these asteroids.
Fabrizio De Marchi - One of the best experts on this subject based on the ideXlab platform.
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space tests of the strong equivalence principle bepicolombo and the sun earth Lagrangian Points opportunity
International Journal of Modern Physics D, 2017Co-Authors: Fabrizio De Marchi, G CongedoAbstract:The validity of General Relativity (GR), after 100 years, is supported by solid experimental evidence. However, there is a lot of interest in pushing the limits of precision by other experiments. Here, we focus our attention on the equivalence principle (EP), in particular, the strong form. The results of ground experiments and Lunar Laser Ranging (LLR) have provided the best upper limit on the Nordtvedt parameter η that models deviations from the strong EP. Its uncertainty is currently σ[η] = 4.4 × 10−4. In the first part of this paper, we will describe the experiment, to measure η, that will be done by the future mission BepiColombo (BC). The expected precision on η is ≈ 10−5. In the second part, we will consider the ranging between the Earth and a spacecraft (SC) orbiting near the Sun–Earth Lagrangian Points to get an independent measurement of η. In this case, we forecast a constraint similar to that achieved by LLR.
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Space tests of the strong equivalence principle: BepiColombo and the Sun–Earth Lagrangian Points opportunity
International Journal of Modern Physics D, 2017Co-Authors: Fabrizio De Marchi, G CongedoAbstract:The validity of General Relativity (GR), after 100 years, is supported by solid experimental evidence. However, there is a lot of interest in pushing the limits of precision by other experiments. Here, we focus our attention on the equivalence principle (EP), in particular, the strong form. The results of ground experiments and Lunar Laser Ranging (LLR) have provided the best upper limit on the Nordtvedt parameter η that models deviations from the strong EP. Its uncertainty is currently σ[η] = 4.4 × 10−4. In the first part of this paper, we will describe the experiment, to measure η, that will be done by the future mission BepiColombo (BC). The expected precision on η is ≈ 10−5. In the second part, we will consider the ranging between the Earth and a spacecraft (SC) orbiting near the Sun–Earth Lagrangian Points to get an independent measurement of η. In this case, we forecast a constraint similar to that achieved by LLR.
-
Space tests of the strong equivalence principle: BepiColombo and the Sun–Earth Lagrangian Points opportunity
International Journal of Modern Physics D, 2017Co-Authors: Fabrizio De Marchi, G CongedoAbstract:The validity of General Relativity (GR), after 100 years, is supported by solid experimental evidence. However, there is a lot of interest in pushing the limits of precision by other experiments. Here, we focus our attention on the equivalence principle (EP), in particular, the strong form. The results of ground experiments and Lunar Laser Ranging (LLR) have provided the best upper limit on the Nordtvedt parameter [Formula: see text] that models deviations from the strong EP. Its uncertainty is currently [Formula: see text]. In the first part of this paper, we will describe the experiment, to measure [Formula: see text], that will be done by the future mission BepiColombo (BC). The expected precision on [Formula: see text] is [Formula: see text]. In the second part, we will consider the ranging between the Earth and a spacecraft (SC) orbiting near the Sun–Earth Lagrangian Points to get an independent measurement of [Formula: see text]. In this case, we forecast a constraint similar to that achieved by LLR.
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space tests of the strong equivalence principle bepicolombo and the sun earth Lagrangian Points opportunity
arXiv: General Relativity and Quantum Cosmology, 2017Co-Authors: Fabrizio De Marchi, G CongedoAbstract:The validity of General Relativity, after 100 years, is supported by solid experimental evidence. However, there is a lot of interest in pushing the limits of precision by other experiments. Here we focus our attention on the equivalence principle, in particular the strong form. The results of ground experiments and lunar laser ranging have provided the best upper limit on the Nordtvedt parameter {\eta} that models deviations from the strong equivalence principle. Its uncertainty is currently {\sigma}[{\eta}] =4.4 $\times$ $10^{-4}$. In the first part of this paper we will describe the experiment, to measure {\eta}, that will be done by the future mission BepiColombo. The expected precision on {\eta} is $\approx$ $10^{-5}$. In the second part we will consider the ranging between the Earth and a spacecraft orbiting near the Sun-Earth Lagrangian Points to get an independent measurement of {\eta}. In this case, we forecast a constraint similar to that achieved by lunar laser ranging.
-
testing the strong equivalence principle with spacecraft ranging towards the nearby Lagrangian Points
Physical Review D, 2016Co-Authors: G Congedo, Fabrizio De MarchiAbstract:General relativity is supported by great experimental evidence. Yet there is a lot of interest in precisely setting its limits with on going and future experiments. A question to answer is about the validity of the Strong Equivalence Principle. Ground experiments and Lunar Laser Ranging have provided the best upper limit on the Nordtvedt parameter $\sigma[\eta]=4.4\times 10^{-4}$. With the future planetary mission BepiColombo, this parameter will be further improved by at least an order of magnitude. In this paper we envisage yet another possible testing environment with spacecraft ranging towards the nearby Sun-Earth collinear Lagrangian Points. Neglecting errors in planetary masses and ephemerides, we forecast $\sigma[\eta]=6.4\,(2.0)\times10^{-4}$ (5 yr integration time) via ranging towards $L_1$ in a realistic (optimistic) scenario depending on current (future) range capabilities and knowledge of the Earth's ephemerides. A combined measurement, $L_1$+$L_2$, gives instead $4.8\,(1.7)\times10^{-4}$. In the optimistic scenario a single measurement of one year would be enough to reach $\approx3\times10^{-4}$. All figures are comparable with Lunar Laser Ranging, but worse than BepiColombo. Performances could be much improved if data were integrated over time and over the number of satellites flying around either of the two Lagrangian Points. We point out that some systematics (gravitational perturbations of other planets or figure effects) are much more in control compared to other experiments. We do not advocate a specific mission to constrain the Strong Equivalence Principle, but we do suggest analysing ranging data of present and future spacecrafts flying around $L_1$/$L_2$ (one key mission is, for instance, LISA Pathfinder). This spacecraft ranging would be a new and complementary probe to constrain the Strong Equivalence Principle in space.
