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1
Agrusa, Harrison F., Yun Zhang, Derek C. Richardson, Petr Pravec, Matija Ćuk, Patrick Michel, Ronald-Louis Ballouz et al. „Direct N-body Simulations of Satellite Formation around Small Asteroids: Insights from DART’s Encounter with the Didymos System“. Planetary Science Journal 5, Nr. 2 (01.02.2024): 54. http://dx.doi.org/10.3847/psj/ad206b.
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Abstract We explore binary asteroid formation by spin-up and rotational disruption considering the NASA DART mission's encounter with the Didymos–Dimorphos binary, which was the first small binary visited by a spacecraft. Using a suite of N-body simulations, we follow the gravitational accumulation of a satellite from meter-sized particles following a mass-shedding event from a rapidly rotating primary. The satellite’s formation is chaotic, as it undergoes a series of collisions, mergers, and close gravitational encounters with other moonlets, leading to a wide range of outcomes in terms of the satellite's mass, shape, orbit, and rotation state. We find that a Dimorphos-like satellite can form rapidly, in a matter of days, following a realistic mass-shedding event in which only ∼2%–3% of the primary's mass is shed. Satellites can form in synchronous rotation due to their formation near the Roche limit. There is a strong preference for forming prolate (elongated) satellites, although some simulations result in oblate spheroids like Dimorphos. The distribution of simulated secondary shapes is broadly consistent with other binary systems measured through radar or lightcurves. Unless Dimorphos's shape is an outlier, and considering the observational bias against lightcurve-based determination of secondary elongations for oblate bodies, we suggest there could be a significant population of oblate secondaries. If these satellites initially form with elongated shapes, a yet-unidentified pathway is needed to explain how they become oblate. Finally, we show that this chaotic formation pathway occasionally forms asteroid pairs and stable triples, including coorbital satellites and satellites in mean-motion resonances.
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Raghuprasad, Puthalath Koroth. „Synchronous, Nonsynchronous and Negative Rotations: How Spin and Gravity Orchestrate Planetary Motions“. Applied Physics Research 12, Nr. 2 (31.01.2020): 1. http://dx.doi.org/10.5539/apr.v12n2p1.
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This study identifies the unique features accompanying the phenomenon of synchronous rotation of the major (proximal) satellites of the gas giants and the earth’s moon, and the special features leading to the ‘negative’ rotation of Venus, Uranus and Pluto, as well as the most peripheral small satellites of the gas giants. Such features help us understand how these phenomena occur but also, by combining all of the observations help explain other (regular) planetary motions as well. In the synchronously rotating satellites, the salient features are the satellites’ low axial tilts and both the orbital speed and the axial rotation speed increasing with proximity to the mother body. In “negative” rotation, axial tilts are in excess of 120° and the axial rotation speeds are significantly delayed; this delay is most pronounced in Venus, which has an axial tilt of -174°. A scrutiny of the orbital parameters of all the satellites of the gas giants alone will yield sufficient data to propose a working hypothesis of how mutual gravitation, combined with spin (axial rotation and orbital motion), the distance from the mother, and centrifugal force can explain all motions. It confirms our belief that the process of planetary motions is a continuum from the synchronous, through degrees of non-synchronicity (or regular orbits), to the negative rotations, all depending on the degree of influence from mother bodies, as a product of distances from them. Thus, the nearest large satellites with the least axial tilts display synchronous rotation. Those satellites that are intermediate in distance from the mother show nonsynchronous axial rotation and correspondingly slower orbital speeds. The small peripheral satellites display axial tilts over 120 degrees and rotate negatively. In all these orbital motions, centrifugal force is the crucial restraining influence; lest, the orbiting bodies will tend to fall into the mother bodies. How all these pieces of the puzzle fit together in the orderly movements of bodies in the universe is the underlying theme of this article.
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Lieske, J. H. „IAU North Poles and Rotation Parameters for Natural Satellites“. Symposium - International Astronomical Union 156 (1993): 351–56. http://dx.doi.org/10.1017/s0074180900173498.
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In 1970 the IAU defined any object'snorthpole to be that axis of rotation which lies north of the solar system's invariable plane. A competing definition in widespread use at some institutions followed the “right hand rule” whereby the “north” axis of rotation was generally said to be that that of the rotational angular momentum.A Working Group has periodically updated the recommended values of planet and satellite poles and rotation rates in accordance with the IAU definition of north and the IAU definition of prime meridian.In this paper we review the IAU definitions ofnorthand of the location ofprime meridianand we present the algorithm which has been employed in determining the rotational parameters of the natural satellites.
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Van Hoolst, Tim. „The libration and interior structure of large icy satellites and Mercury“. Proceedings of the International Astronomical Union 9, S310 (Juli 2014): 1–8. http://dx.doi.org/10.1017/s1743921314007698.
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AbstractLongitudinal librations are periodic changes in the rotation angle of a planet or satellite. Their observation and subsequent interpretation have profoundly increased our understanding of the interior structure of Mercury. Likewise, libration is thought to provide important constraints on the interior structure of icy satellites. Here we study the libration of Mercury and large icy satellites rotating synchronously with their orbital motion and explain how it depends on the interior structure.
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Pashkevich, Vladimir V., und Andrey N. Vershkov. „Geodetic Precession of the Sun, Solar System Planets, and their Satellites“. Artificial Satellites 57, Nr. 1 (01.03.2022): 77–109. http://dx.doi.org/10.2478/arsa-2022-0005.
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Abstract The effect of the geodetic precession is the most significant relativistic effect in the rotation of celestial bodies. In this article, the new geodetic precession values for the Sun, the Moon, and the Solar System planets have been improved over the previous version by using more accurate rotational element values. For the first time, the relativistic effect of the geodetic precession for some planetary satellites (J1–J4, S1–S6, S8–S18, U1–U15, N1, and N3–N8) with known quantities of the rotational elements was studied in this research. The calculations of the values of this relativistic effect were carried out by the method for studying any bodies of the Solar System with long-time ephemeris. As a result, the values of the geodetic precession were first determined for the Sun, planets in their rotational elements, and for the planetary satellites in the Euler angles relative to their proper coordinate systems and in their rotational elements. In this study, with respect to the previous version, additional and corrected values of the relativistic influence of Martian satellites (M1 and M2) on Mars were calculated. The largest values of the geodetic rotation of bodies in the Solar System were found in Jovian satellite system. Further, in decreasing order, these values were found in the satellite systems of Saturn, Neptune, Uranus, and Mars, for Mercury, for Venus, for the Moon, for the Earth, for Mars, for Jupiter, for Saturn, for Uranus, for Neptune, and for the Sun. First of all, these are the inner satellites of Jupiter: Metis (J16), Adrastea (J15), Amalthea (J5), and Thebe (J14) and the satellites of Saturn: Pan (S18), Atlas (S15), Prometheus (S16), Pandora (S17), Epimetheus (S11), Janus (S10), and Mimas (S1), whose values of geodetic precession are comparable to the values of their precession. The obtained numerical values for the geodetic precession for the Sun, all the Solar System planets, and their satellites (E1, M1, M2, J1–J5, J14–J16, S1–S6, S8–S18, U1–U15, N1, and N3–N8) can be used to numerically study their rotation in the relativistic approximation and can also be used to estimate the influence of relativistic effects on the orbital–rotational dynamics of bodies of exoplanetary systems.
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Pashkevich, Vladimir V., und Andrey N. Vershkov. „Geodetic Precession of the Sun, Solar System Planets, and their Satellites“. Artificial Satellites 57, Nr. 1 (01.03.2022): 77–109. http://dx.doi.org/10.2478/arsa-2022-0005.
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Abstract The effect of the geodetic precession is the most significant relativistic effect in the rotation of celestial bodies. In this article, the new geodetic precession values for the Sun, the Moon, and the Solar System planets have been improved over the previous version by using more accurate rotational element values. For the first time, the relativistic effect of the geodetic precession for some planetary satellites (J1–J4, S1–S6, S8–S18, U1–U15, N1, and N3–N8) with known quantities of the rotational elements was studied in this research. The calculations of the values of this relativistic effect were carried out by the method for studying any bodies of the Solar System with long-time ephemeris. As a result, the values of the geodetic precession were first determined for the Sun, planets in their rotational elements, and for the planetary satellites in the Euler angles relative to their proper coordinate systems and in their rotational elements. In this study, with respect to the previous version, additional and corrected values of the relativistic influence of Martian satellites (M1 and M2) on Mars were calculated. The largest values of the geodetic rotation of bodies in the Solar System were found in Jovian satellite system. Further, in decreasing order, these values were found in the satellite systems of Saturn, Neptune, Uranus, and Mars, for Mercury, for Venus, for the Moon, for the Earth, for Mars, for Jupiter, for Saturn, for Uranus, for Neptune, and for the Sun. First of all, these are the inner satellites of Jupiter: Metis (J16), Adrastea (J15), Amalthea (J5), and Thebe (J14) and the satellites of Saturn: Pan (S18), Atlas (S15), Prometheus (S16), Pandora (S17), Epimetheus (S11), Janus (S10), and Mimas (S1), whose values of geodetic precession are comparable to the values of their precession. The obtained numerical values for the geodetic precession for the Sun, all the Solar System planets, and their satellites (E1, M1, M2, J1–J5, J14–J16, S1–S6, S8–S18, U1–U15, N1, and N3–N8) can be used to numerically study their rotation in the relativistic approximation and can also be used to estimate the influence of relativistic effects on the orbital–rotational dynamics of bodies of exoplanetary systems.
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Velgas, Lev Borisovich, und Liia Lvovna Iavolinskaia. „Seven main discoveries, rigorously proven“. Interactive science, Nr. 6 (40) (21.06.2019): 103–5. http://dx.doi.org/10.21661/r-496981.
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We are striving to prove that all planets rotate around their axis due to their satellites. Rotation of the collateral gravitation is analogous for all the planets, for the Sun as well. The Sun, as well as every single planet, can have multiple satellites. Satellite and planet’s collateral gravitation, if it moves because of satellite’s movement around the orbit, rotates the planet or the Sun. The article proves that collateral gravitation of the Moon and the Earth, that moves around the Earth due to Moon’s movement around the Earth, rotates the Earth around it’s axis.
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Zhang, Xiaozhen, Yao Kong, Xiaochun Lu und Decai Zou. „Contribution of Etalon Observation to Earth Rotation Parameters under a New Observation Scenario“. Applied Sciences 12, Nr. 10 (13.05.2022): 4936. http://dx.doi.org/10.3390/app12104936.
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The standard products of the International Laser Ranging Service (ILRS) are mainly based on the two laser geodynamics satellites (LAGEOS) due to the sparse observations of the Etalon satellites. With improvements in the ability to track high-altitude satellites, ILRS conducted a 3-month Etalon tracking campaign. In this paper, we study the contribution of more Etalon observations in the new observation scenario to weekly ILRS products, such as station coordinates, Earth rotation parameters (ERPs) and satellite orbit. We compare the ILRS products estimated from LAGEOS-only solutions and LAGEOS+Etalon solutions. In the new observation scenario of 2019, the numbers of observations of Etalon satellites are 1.4 and 1.7 times larger than those in 2018. It is shown that the quality of station coordinates, and the satellite orbit of LAGESOS satellites are only slightly affected by the increase in Etalon observations of the campaign. However, for station 1868, which is dedicated to high-altitude satellites, the root mean square (RMS) values of the residuals in the N, E, and U components are improved by 3.1 cm, 2.1 cm and 2.3 cm, respectively. The internal precision of orbit for Etalon-1/2 satellites in tangle and normal directions are improved by 1.5 cm and 2.9 cm, respectively. Most remarkably, the standard deviations for Xp, Yp and LOD can be improved by 6.9%, 14.3% and 5.1%, respectively, compared with the International Earth Rotation System (IERS)-14-C04 series. With our research, the ILRS could increase efforts on Etalon satellite tracking without affecting the routine observations of LAGEOS satellites.
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Pashkevich, V. V., und A. N. Vershkov. „Secular geodetic rotation of celestial bodies in the system of Jupiter’s moons“. Publications of the Pulkovo Observatory 235 (Dezember 2024): 51–68. https://doi.org/10.31725/0367-7966-2024-235-51-68.
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This article studies the relativistic effect of geodetic precession in the rotation around their axes of Jupiter and its 94 satellites for which ephemerides are known. As a result, the most significant secular terms of the geodetic rotation of these celestial bodies were determined for the first time: 1. for Jupiter relative to the barycenter of the Solar System and the plane of the mean orbit of Jupiter at the epoch J2000.0 in Euler angles, in the perturbing terms of physical libration and in the absolute value of the vector of angular rotation of the geodetic rotation of the body under study; 2. for 8 regular (4 inner (Metis J16, Adrastea J15, Amalthea J5 and Thebe J14)) and 4 Galilean (Io J1, Europa J2, Ganymede J3 and Callisto J4))) satellites of Jupiter relative to: a) the barycenter of the Solar system and the plane of the mean orbit of the satellite under study at epoch J2000.0 in Euler angles, in the perturbing terms of the physical libration and in the absolute value of the vector of angular rotation of the geodetic rotation of the body under study; b) the barycenter of the Solar system and the plane of the mean orbit of the barycenter of the Jovian system at epoch J2000.0 in Euler angles, in the perturbing terms of the physical libration and in the absolute value of the vector of angular rotation of the geodetic rotation of the body under study; c) the barycenter of the Jupiter satellite system and the plane of the mean orbit of the studied satellite of the J2000.0 epoch in the perturbing terms of the physical libration and in the absolute value of the angular rotation vector of the geodetic rotation of the studied body; 3. for 86 irregular satellites (J6–J13, J17–J72, J5501–J5507, J5509–J5523) of Jupiter relative to: a) the barycenter of the Solar system in the absolute value of the angular rotation vector of the geodetic rotation of the studied body; b) the barycenter of the Jupiter satellite system in the absolute value of the angular rotation vector of the geodetic rotation of the studied body. For the J2000.0 epoch, the mean orbits of the studied celestial bodies and the mean orbit of the barycenter of the Jovian system were calculated. For regular satellites, the values of the angles of inclination of their equator to their own orbits were determined. The obtained analytical values of the geodetic precession of the studied celestial bodies can be used for a numerical study of the rotation of these bodies in the relativistic approximation.
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Schildknecht, T., I. Bauersima, U. Hugentobler, A. Verdun und G. Beutler. „CQSSP: A New Technique for Establishing the Tie Between the Stellar and Quasar Celestial Reference Frames“. International Astronomical Union Colloquium 127 (1991): 341–47. http://dx.doi.org/10.1017/s0252921100064174.
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AbstractUsing artificial satellites as transfer objects the project “Coupled Quasar-Satellite-Star Positioning” represents an independent method for linking quasar and stellar reference frames. Optical observations of close approaches between reference stars and satellites yield satellite positions in the stellar reference frame. On the other hand high precision satellite orbits in the International Earth Rotation Service (IERS) terrestrial reference frame are obtained from laser or radiometric observations. Using IERS earth rotation parameters and adopted transformation models the satellite and eventually the star positions can be expressed in the IERS quasar celestial reference frame. In this paper we describe the CQSSP project and assess its capability for providing an accurate tie between tho two metioned celestial reference frames.
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Li, Xingxing, Hongmin Zhang, Keke Zhang, Yongqiang Yuan, Wei Zhang und Yujie Qin. „Earth Rotation Parameters Estimation Using GPS and SLR Measurements to Multiple LEO Satellites“. Remote Sensing 13, Nr. 15 (03.08.2021): 3046. http://dx.doi.org/10.3390/rs13153046.
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Earth rotation parameters (ERP) are one of the key parameters in realization of the International Terrestrial Reference Frames (ITRF). At present, the International Laser Ranging Service (ILRS) generates the satellite laser ranging (SLR)-based ERP products only using SLR observations to Laser Geodynamics Satellite (LAGEOS) and Etalon satellites. Apart from these geodetic satellites, many low Earth orbit (LEO) satellites of Earth observation missions are also equipped with laser retroreflector arrays, and produce a large number of SLR observations, which are only used for orbit validation. In this study, we focus on the contribution of multiple LEO satellites to ERP estimation. The SLR and Global Positioning System (GPS) observations of the current seven LEO satellites (Swarm-A/B/C, Gravity Recovery and Climate Experiment (GRACE)-C/D, and Sentinel-3A/B) are used. Several schemes are designed to investigate the impact of LEO orbit improvement, the ERP quality of the single-LEO solutions, and the contribution of multiple LEO combinations. We find that ERP estimation using an ambiguity-fixed orbit can attain a better result than that using ambiguity-float orbit. The introduction of an ambiguity-fixed orbit contributes to an accuracy improvement of 0.5%, 1.1% and 15% for X pole, Y pole and station coordinates, respectively. In the multiple LEO satellite solutions, the quality of ERP and station coordinates can be improved gradually with the increase in the involved LEO satellites. The accuracy of X pole, Y pole and length-of-day (LOD) is improved by 57.5%, 57.6% and 43.8%, respectively, when the LEO number increases from three to seven. Moreover, the combination of multiple LEO satellites is able to weaken the orbit-related signal existing in the single-LEO solution. We also investigate the combination of LEO satellites and LAGEOS satellites in the ERP estimation. Compared to the LAGEOS solution, the combination leads to an accuracy improvement of 0.6445 ms, 0.6288 ms and 0.0276 ms for X pole, Y pole and LOD, respectively. In addition, we explore the feasibility of a one-step method, in which ERP and the orbit parameters are jointly determined, based on SLR and GPS observations, and present a detailed comparison between the one-step solution and two-step solution.
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Pashkevich, Vladimir V., und Andrey N. Vershkov. „Relativistic Effects in the Rotation of Jupiter’s Inner Satellites“. Artificial Satellites 55, Nr. 3 (01.09.2020): 118–29. http://dx.doi.org/10.2478/arsa-2020-0009.
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AbstractThe most significant relativistic effects (the geodetic precession and the geodetic nutation, which consist of the effect of the geodetic rotation) in the rotation of Jupiter’s inner satellites were investigated in this research. The calculations of the most essential secular and periodic terms of the geodetic rotation were carried out by the method for studying any bodies of the solar system with long-time ephemeris. As a result, for these Jupiter’s satellites, these terms of their geodetic rotation were first determined in the rotational elements with respect to the International Celestial Reference Frame (ICRF) equator and the equinox of the J2000.0 and in the Euler angles relative to their proper coordinate systems. The study shows that in the solar system there are objects with significant geodetic rotation, due primarily to their proximity to the central body, and not to its mass.
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Zhou, Wei, Hongliang Cai, Ziqiang Li, Chengpan Tang, Xiaogong Hu und Wanke Liu. „Research on the Rotational Correction of Distributed Autonomous Orbit Determination in the Satellite Navigation Constellation“. Remote Sensing 14, Nr. 14 (09.07.2022): 3309. http://dx.doi.org/10.3390/rs14143309.
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The autonomous orbit determination of the navigation constellation uses only bidirectional ranging data of the inter-satellite link for data processing. The lack of space-time benchmark information related to the Earth inevitably causes overall rotational uncertainty in the constellation, leading to a decrease in orbit accuracy and affecting user positioning accuracy. This study (1) introduces a method for rotation correction in distributed autonomous orbit determination based on inter-satellite bidirectional ranging; (2) conducts constellation autonomous orbit determination and time synchronization processing experiments based on inter-satellite ranging data for the 24 medium Earth orbit (MEO) satellites in the Beidou-3 global satellite navigation system (BDS-3); and (3) makes comparative analyses on the accuracy of autonomous orbit determination based on three rotation correction cases, including a no-rotation-correction case, independent satellite constraints case, and global satellite constraints case. The experimental results are described as follows. For the no-rotation-correction case, the prediction error of the orbital inclination angle (iot, i) for the entire constellation on the 30th day was 2.11 × 10−7/rad, the prediction error of the right ascension of the ascending point (Omega, Ω) was 2.25 × 10−7/rad, and the average root mean square (RMS) of the user range error (URE) for the entire constellation orbit was 1.41 m. In the autonomous orbit determination experiment with independent constraints on satellites, the prediction error of i for the entire constellation on the 30th day was 5.43 × 10−7/rad, the prediction error of Ω was 2.03 × 10−7/rad, and the average RMS of the orbital URE for the entire constellation was 1.09 m. In the autonomous orbit determination experiment with global satellite constraints, the prediction error of i for the entire constellation on the 30th day was 5.31 × 10−7/rad, the prediction error of Ω was 1.95 × 10−7/rad, and the RMS of the orbital URE for the entire constellation was 0.94 m. According to the analysis of the above experimental results, compared with the autonomous orbit determination under the no-rotation-correction case, the adoption of an algorithm for independent satellite constraints to correct the overall constellation rotation weakens the constellation rotation influence; however, it may destroy the overall constellation configuration, which affects the stability of autonomous orbit determination. Finally, the algorithm based on global satellite constraints both impairs the influence of constellation rotation and maintains the overall constellation configuration.
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Vershkov, A. N., und V. V. Pashkevich. „Geodetic Rotation of Neptune’s Satellites“. Solar System Research 56, Nr. 5 (12.09.2022): 299–307. http://dx.doi.org/10.1134/s0038094622050070.
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Henrard, Jacques, und Gabriel Schwanen. „Rotation of Synchronous Satellites Application to the Galilean Satellites“. Celestial Mechanics and Dynamical Astronomy 89, Nr. 2 (2004): 181–200. http://dx.doi.org/10.1023/b:cele.0000034515.57763.33.
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Abbot, R. I., R. W. King, Y. Bock und C. C. Counselman. „Earth rotation from radio interferometric tracking of GPS satellites“. Symposium - International Astronomical Union 128 (1988): 209–13. http://dx.doi.org/10.1017/s0074180900119503.
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Radio-interferometric tracking of the Global Positioning System (GPS) satellites offers a new technique for regular monitoring of variations in the earth's rotation. The observations are sensitive to pole position and length-of-day, at a level of precision which may make this technique competitive with satellite and lunar laser ranging and very long baseline interferometry (VLBI). The present limitations are the number of satellites and tracking stations available and inadequate modeling of non-gravitational forces on the satellites. The potential advantages are rapid turn-around and minimal incremental cost. We have performed a preliminary analysis using six days of observations from a four-station network. Comparison of earth rotation values from our GPS analysis with values obtained by VLBI and laser ranging reveals differences after five days of 0.9 ms in UT1, 0.04″ in x and 0.07″ in y. These differences reflect errors in the GPS determinations due primarily to inadequate modeling of non-gravitational forces.
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Herbert-Fort, Stéphane, Dennis Zaritsky, Yeun Jin Kim, Jeremy Bailin und James E. Taylor. „Rotation of Galaxy Dark Matter Halos“. Proceedings of the International Astronomical Union 2, S235 (August 2006): 104. http://dx.doi.org/10.1017/s1743921306005394.
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AbstractThe degree to which outer dark matter halos of spiral galaxies rotate with the disk is sensitive to their accretion history and may be probed with associated satellite galaxies. We use the Steward Observatory Bok telescope to measure the sense of rotation of nearby isolated spirals and combine these data with those of their associated satellites (drawn from SDSS) to directly test predictions from numerical simulations. We aim to constrain models of galaxy formation by measuring the projected component of the halo angular momentum that is aligned with that of spiral galaxy disks, Jz. We find the mean bulk rotation of the ensemble satellite system to be co-rotating with the disk with a velocity of 22 ± 13 km/s, in general agreement with previous observational studies and suggesting that galaxy disks could be formed by halo baryons collapsing by a factor of ≈10. We also find a prograde satellite fraction of 51% and Jz, of the satellite system to be positively correlated with the disk, albeit at low significance (2655 ± 2232 kpc km/s).
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Strigari, Louis E. „Kinematics of Milky Way Satellites: Mass Estimates, Rotation Limits, and Proper Motions“. Advances in Astronomy 2010 (2010): 1–11. http://dx.doi.org/10.1155/2010/407394.
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In the past several years kinematic data sets from Milky Way satellite galaxies have greatly improved, furthering the evidence that these systems are the most dark matter dominated objects known. This paper discusses a maximum likelihood formalism that extracts important quantities from these kinematic data sets, including the amplitude of a rotational signal, proper motions, and the mass distributions. Using a simple model for galaxy rotation it is shown that the expected error on the amplitude of a rotational signal is∼0.5 kms−1with∼103stars from either classical or ultra-faint satellites. As an example Sculptor is analyzed for the presence of a rotational signal; no significant detection of rotation is found, with a 90% c.l. upper limit of∼2 kms−1. A criterion for model selection is presented that determines the parameters required to describe the dark matter halo density profiles and the stellar velocity anisotropy. Applied to four data sets with a wide range of velocities, models with variable velocity anisotropy are preferred relative to those with constant velocity anisotropy, and that central dark matter profiles both less cuspy and more cuspy than Lambda-Cold Dark Matter-based fits are equally acceptable.
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Araújo, Alexandre, und Adriana Valio. „Dependence of Stellar Differential Rotation on Effective Temperature and Rotation: An Analysis from Starspot Transit Mapping“. Astrophysical Journal 956, Nr. 2 (01.10.2023): 141. http://dx.doi.org/10.3847/1538-4357/acfc1b.
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Abstract Stellar rotation is crucial for studying stellar evolution, since it provides information about age, angular momentum transfer, and magnetic fields of stars. In the case of the Sun, due to its proximity, detailed observation of sunspots at various latitudes and longitudes allows a precise estimation of the solar rotation period and its differential rotation. Here, we present for the first time an analysis of stellar differential rotation using starspot transit mapping as a means of detecting differential shear in solar-type and M stars. The aim of this study is to investigate the relationship between rotational shear, ΔΩ, and both the star's effective temperature (T eff) and its average rotation period ( P ¯ ). We present differential rotation profiles derived from previously collected spot transit mapping data for 13 slowly rotating stars (P rot ≥ 4.5 days), with spectral types ranging from M to F, which were observed by the Kepler and CoRoT satellites. Our findings reveal a significant negative correlation between rotational shear and the mean period of stellar rotation (correlation coefficient of −0.77), which may be an indicator of stellar age. On the other hand, a weak correlation was observed between differential rotation and the effective temperature of the stars. Overall, the study provides valuable insights into the complex relationship between stellar parameters and differential rotation, which may enhance our understanding of stellar evolution and magnetic dynamos.
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Zhang, Derui, Hao Wang und Qing Zhao. „Non-Cooperative Target Ranging Based on High-Orbit Single-Star Temporal–Spatial Characteristics“. Applied Sciences 14, Nr. 23 (02.12.2024): 11232. https://doi.org/10.3390/app142311232.
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A visible light camera payload with star-sensitive functionality was installed to measure the distance between a non-cooperative target satellite and a high-orbit satellite. The rotation matrix was used to calculate the pointing vector from the center of the satellite’s star-sensitive camera axis to the target satellite. Multiple position imaging was achieved, and the moving window approach was used to establish two sets of equations relating the pointing vectors to the positions of binary satellites. To simplify the calculations, the target satellite’s eccentricity was assumed to be small (0 to 0.001), allowing elliptical orbits to be approximated as circular. Additionally, short-interval (1-min) imaging measurements were taken, assuming a small inclination of the target satellite (0.0° to 0.4°). This resulted in the construction of a ranging model with high accuracy, producing a ranging error of less than 5% of the actual distance.
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Curir, Anna, Giuseppe Murante, Eva Poglio und Álvaro Villalobos. „The dual nature of the Milky Way stellar halo“. Proceedings of the International Astronomical Union 6, S271 (Juni 2010): 145–52. http://dx.doi.org/10.1017/s1743921311017558.
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AbstractThe theory of the Milky Way formation, in the framework of the ΛCDM model, predicts galactic stellar halos to be built from multiple accretion events starting from the first structure to collapse in the Universe.Evidences in the past few decades have indicated that the Galactic halo consists of two overlapping structural components, an inner and an outer halo. We provide a set of numerical N-body simulations aimed to study the formation of the outer Milky Way (MW) stellar halo through accretion events between a (bulgeless) MW-like system and a satellite galaxy. After these minor mergers take place, in several orbital configurations, we analyze the signal left by satellite stars in the rotation velocity distribution. The aim is to explore the orbital conditions of the mergers where a signal of retrograde rotation in the outer part of the halo can be obtained, in order to give a possible explanation of the observed rotational properties of the MW stellar halo.Our results show that the dynamical friction has a fundamental role in assembling the final velocity distributions originated by different orbits and that retrograde satellites moving on low inclination orbits deposit more stars in the outer halo regions and therefore can produce the counter-rotating behavior observed in the outer MW halo.
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Rufu, Raluca, und Robin M. Canup. „Coaccretion + Giant-impact Origin of the Uranus System: Tilting Impact“. Astrophysical Journal 928, Nr. 2 (31.03.2022): 123. http://dx.doi.org/10.3847/1538-4357/ac525a.
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Abstract The origin of the Uranian satellite system remains uncertain. The four major satellites have nearly circular, coplanar orbits, and the ratio of the satellite system to planetary mass resembles Jupiter’s satellite system, suggesting the Uranian system was similarly formed within a disk produced by gas coaccretion. However, Uranus is a retrograde rotator with a high obliquity. The satellites orbit in its highly tilted equatorial plane in the same sense as the planet’s retrograde rotation, a configuration that cannot be explained by coaccretion alone. In this work, we investigate the first stages of the coaccretion + giant-impact scenario proposed by Morbidelli et al. (2012) for the origin of the Uranian system. In this model, a satellite system formed by coaccretion is destabilized by a giant impact that tilts the planet. The primordial satellites collide and disrupt, creating an outer debris disk that can reorient to the planet’s new equatorial plane and accrete into Uranus’ four major satellites. The needed reorientation out to distances comparable to outermost Oberon requires that the impact creates an inner disk with ≥1% of Uranus’ mass. We here simulate giant impacts that appropriately tilt the planet and leave the system with an angular momentum comparable to that of the current system. We find that such impacts do not produce inner debris disks massive enough to realign the outer debris disk to the post-impact equatorial plane. Although our results are inconsistent with the apparent requirements of a coaccretion + giant-impact model, we suggest alternatives that merit further exploration.
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Jacobsen, K. „SYSTEMATIC GEOMETRIC IMAGE ERRORS OF VERY HIGH RESOLUTION OPTICAL SATELLITES“. ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences XLII-1 (26.09.2018): 233–38. http://dx.doi.org/10.5194/isprs-archives-xlii-1-233-2018.
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<p><strong>Abstract.</strong> Very high resolution optical satellites are imaging the object space by a combination of CCD-lines in one direction and by time, speed and satellite rotation in the other direction. The combination of the CCD-lines usually is known by pre-calibration. Remaining errors of the pre-calibration, also slightly depending upon the satellite movement and rotation, with few exceptions are usually small up to negligible. This may not be the case for the image component in the scan direction and the alignment of the line combinations - they are controlled by giros and stellar cameras. Stellar cameras are compensating giro drifts, but their recording frequency is limited as well as in general the accuracy of the satellite view direction. In addition the satellites may show a jitter caused by the fast rotation from one pointed area to another. Not all giros are able to record the jitter frequency. A limited accuracy of the view direction is causing systematic image errors in relation to the used mathematical model of geometric reconstruction.</p><p> The systematic image errors can be determined theoretically by image orientation based on ground control points (GCPs), but usually not a satisfying number and distribution of GCPs is available. Another possibility is the analysis of the intersection of corresponding rays in a stereo model and an analysis of generated height models against reference height models. Here also free of charge available height models as the SRTM Digital Surface Model (DSM) or AW3D30 can be used. Several very high resolution satellite cameras have been analyzed; this includes images from WorldView-2, WorldView-4, Kompsat-3, Kompsat-1, Pleiades, Cartosat-1, ZY3, OrbView-3, QuickBird, IKONOS, ASTER, IRS-1C, SPOT, SPOT-5 HRS, EROS-B, IKONOS, QuickBird, OrbView and GeoEye but only results of the today more important satellites are shown in detail. For few satellites the systematic image errors can be ignored, but others require a correction which may be just a levelling of the DSM but also a higher degree of deformation up to a compensation of the satellite jitter effect.</p><p> The used method cannot be named as calibration due to variation from image to image, only the character and size of deformation is typical for the used special optical satellite, but it depends also upon the operating conditions as fast satellite rotation. Due to the very high number of reference points in a DSM the determination of systematic image errors is independent upon random errors and also high frequent jitter can be determined with a standard deviation down to 0.1 ground sampling distance (GSD) or even better.</p>
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Coyette, Alexis, Rose-Marie Baland und Tim Van Hoolst. „Revisiting the Cassini States of synchronous satellites with an angular momentum approach“. Proceedings of the International Astronomical Union 18, S382 (Dezember 2022): 73–79. http://dx.doi.org/10.1017/s1743921323004118.
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AbstractLike our Moon, the large icy satellites of Jupiter are thought to be in a Cassini State, an equilibrium rotation state characterized by a synchronous rotation rate and a precession rate of the rotation axis equal to that of the normal to the orbit. In these equilibrium states (up to four Cassini States are possible for a solid and rigid satellite), the spin axis of the satellite, the normal to its orbit and the normal to the inertial plane remain coplanar with an obliquity that remains theoretically constant. However, as the gravitational torque exerted on the satellite shows small periodic variations, the orientation of the rotation axis will also vary with time and nutations in obliquity will appear.Here we present a dynamical model for the study of the Cassini States. This model includes the coupling between the polar motion and the spin axis precession/nutation which is neglected in the classical studies. We study the influence of the triaxiality of Ganymede on its four possible Cassini States, use a Toy model of the Moon to illustrate the nutations in obliquity obtained with the dynamical model, and investigate the influence of the presence of a subsurface ocean on the Cassini State I of Europa.
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Liao, Shilong, Zhaoxiang Qi und Zhenghong Tang. „A Differential Measurement Method for Solving the Ephemeris Observability Issues in Autonomous Navigation“. Journal of Navigation 68, Nr. 6 (25.05.2015): 1133–40. http://dx.doi.org/10.1017/s0373463315000417.
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The autonomous navigation of navigation and positioning systems such as the Global Positioning System (GPS) and other Global Navigation Satellite Systems (GNSS) was motivated to improve accuracy and survivability of the navigation function for 180 days without ground contact. These improvements are accomplished by establishing inter-satellite links in the constellation for pseudo-range observations and communications between satellites. But observability issues arise for both ephemeris and clock since the pseudo-range describes only the relative distance between satellites. A differential measurement method is proposed to measure the rotation of the constellation as a whole for the first time. The feasibility of the proposed method is verified by simulations.
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Melnikov, Alexander V., und Ivan I. Shevchenko. „How do the small planetary satellites rotate?“ Proceedings of the International Astronomical Union 5, S263 (August 2009): 167–70. http://dx.doi.org/10.1017/s1743921310001705.
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AbstractWe investigate the problem of the typical rotation states of the small planetary satellites from the viewpoint of the dynamical stability of their rotation. We show that the majority of the discovered satellites with unknown rotation periods cannot rotate synchronously, because no stable synchronous 1:1 spin-orbit state exists for them. They rotate either much faster than synchronously (those tidally unevolved) or, what is much less probable, chaotically (tidally evolved objects or captured slow rotators).
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Mel’nikov, A. V., und I. I. Shevchenko. „Unusual rotation modes of minor planetary satellites“. Solar System Research 41, Nr. 6 (Dezember 2007): 483–91. http://dx.doi.org/10.1134/s0038094607060032.
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Makarov, Valeri V. „EQUILIBRIUM ROTATION OF SEMILIQUID EXOPLANETS AND SATELLITES“. Astrophysical Journal 810, Nr. 1 (25.08.2015): 12. http://dx.doi.org/10.1088/0004-637x/810/1/12.
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Krzysztof, Sośnica. „Impact of the Atmospheric Drag on Starlette, Stella, Ajisai, and Lares Orbits“. Artificial Satellites 50, Nr. 1 (01.03.2015): 1–18. http://dx.doi.org/10.1515/arsa-2015-0001.
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Abstract The high-quality satellite orbits of geodetic satellites, which are determined using Satellite Laser Ranging (SLR) observations, play a crucial role in providing, e.g., low-degree coefficients of the Earth's gravity field including geocenter coordinates, Earth rotation parameters, as well as the SLR station coordinates. The appropriate modeling of non-gravitational forces is essential for the orbit determination of artificial Earth satellites. The atmospheric drag is a dominating perturbing force for satellites at low altitudes up to about 700-1000 km. This article addresses the impact of the atmospheric drag on mean semi-major axes and orbital eccentricities of geodetic spherical satellites: Starlette, Stella, AJISAI, and LARES. Atmospheric drag causes the semi-major axis decays amounting to about ▲a = -1.2, -.12, -.14, and -.30 m/year for LARES, AJISAI, Starlette, and Stella, respectively. The density of the upper atmosphere strongly depends on the solar and geomagnetic activity. The atmospheric drag affects the along-track orbit component to the largest extent, and the out-of-plane to a small extent, whereas the radial component is almost unaffected by the atmospheric drag.
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Qi, Lihua, Dongqiu Xing, Rui Wang und Jingna Cui. „Research on the operational regional coverage of satellite and spacecraft tracking and controlling“. MATEC Web of Conferences 309 (2020): 01005. http://dx.doi.org/10.1051/matecconf/202030901005.
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In view of the problem of building ground stations for tracking and controlling of satellites and spacecraft, considering the fixed angle between the orbit of the satellite or spacecraft and the equatorial surface of the earth, and the difference of longitude between the two circles in succession of the satellite or spacecraft caused by the rotation of the earth, the operation area of the satellite or spacecraft was calculated by using the method of spherical projection of satellite orbit rotation, taking the earth as the reference system. The minimum number of ground stations needed for satellite tracking and controlling was calculated in three cases, by using the mathematical model of sphere ring area and honeycomb coverage. This model was validated by the launch and operation data of Shenzhou 7.
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Volkov, G. Yu, und D. V. Fadyushin. „DYNAMIC CONDITIONS FOR INCREASING THE STRUCTURAL STABILITY OF THE WORKING MECHANISM OF A PLANETARY-ROTARY HYDRAULIC MACHINE“. Spravochnik. Inzhenernyi zhurnal, Nr. 283 (Oktober 2020): 33–39. http://dx.doi.org/10.14489/hb.2020.10.pp.033-039.
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A structural feature of planetary-rotor hydraulic machines (PRHM) is the presence of floating satellites. The satellite forms kinematic pairs with the rotor and stator, which, depending on the applied forces, can change their class. In PRHM with “standouts” of satellites intended for gas media, the kinematic satellite-stator pair operates at critically high values of the pressure angle. Under the influence of the pressure force of the working medium, the satellite, taking up the radial clearance in the gearing, is shifted towards the rotor and pressed against it on both sides of the tooth, and the satellite-stator pair becomes a single-moving pair of class 4. The resulting satellite offset further worsens the conditions for transmitting motion in the satellite-stator pair. As a result, there is a probability of jamming of the mechanism, accompanied by unacceptable deformations, and the satellite's exit from engagement with the stator. From the point of view of the theory of mechanisms and machines, this means that the system loses its structural stability and goes into an undesirable structural state. The article studies the conditions under which inertial forces, overcoming the pressure forces of the working medium, press the satellite against the stator. This eliminates the situation when a kinematic pair characterized by a critically high pressure angle is single-moving. As a result of the performed dynamic analysis, calculated dependencies are obtained that allow determining the rotor rotation speed that provides more reliable operation of the PRHM.
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Volkov, G. Yu, und D. V. Fadyushin. „DYNAMIC CONDITIONS FOR INCREASING THE STRUCTURAL STABILITY OF THE WORKING MECHANISM OF A PLANETARY-ROTARY HYDRAULIC MACHINE“. Spravochnik. Inzhenernyi zhurnal, Nr. 283 (Oktober 2020): 33–39. http://dx.doi.org/10.14489/hb.2020.10.pp.033-039.
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A structural feature of planetary-rotor hydraulic machines (PRHM) is the presence of floating satellites. The satellite forms kinematic pairs with the rotor and stator, which, depending on the applied forces, can change their class. In PRHM with “standouts” of satellites intended for gas media, the kinematic satellite-stator pair operates at critically high values of the pressure angle. Under the influence of the pressure force of the working medium, the satellite, taking up the radial clearance in the gearing, is shifted towards the rotor and pressed against it on both sides of the tooth, and the satellite-stator pair becomes a single-moving pair of class 4. The resulting satellite offset further worsens the conditions for transmitting motion in the satellite-stator pair. As a result, there is a probability of jamming of the mechanism, accompanied by unacceptable deformations, and the satellite's exit from engagement with the stator. From the point of view of the theory of mechanisms and machines, this means that the system loses its structural stability and goes into an undesirable structural state. The article studies the conditions under which inertial forces, overcoming the pressure forces of the working medium, press the satellite against the stator. This eliminates the situation when a kinematic pair characterized by a critically high pressure angle is single-moving. As a result of the performed dynamic analysis, calculated dependencies are obtained that allow determining the rotor rotation speed that provides more reliable operation of the PRHM.
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Proudfoot, Benjamin C. N., Darin A. Ragozzine, William Giforos, Will M. Grundy, Mariah MacDonald und William J. Oldroyd. „Beyond Point Masses. III. Detecting Haumea’s Nonspherical Gravitational Field“. Planetary Science Journal 5, Nr. 3 (01.03.2024): 69. http://dx.doi.org/10.3847/psj/ad26e9.
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Abstract The dwarf planet Haumea is one of the most compelling trans-Neptunian objects to study, hosting two small, dynamically interacting satellites, a family of nearby spectrally unique objects, and a ring system. Haumea itself is extremely oblate due to its 3.9 hr rotation period. Understanding the orbits of Haumea’s satellites, named Hi’iaka and Namaka, requires detailed modeling of both satellite–satellite gravitational interactions and satellite interactions with Haumea’s nonspherical gravitational field (parameterized here as J 2). Understanding both of these effects allows for a detailed probe of the satellites’ masses and Haumea’s J 2 and spin pole. Measuring Haumea’s J 2 provides information about Haumea’s interior, possibly determining the extent of past differentation. In an effort to understand the Haumea system, we have performed detailed non-Keplerian orbit fitting of Haumea’s satellites using a decade of new, ultra-precise observations. Our fits detect Haumea’s J 2 and spin pole at ≳2.5σ confidence. Degeneracies present in the dynamics prevent us from precisely measuring Haumea’s J 2 with the current data, but future observations should enable a precise measurement. Our dynamically determined spin pole shows excellent agreement with past results, illustrating the strength of non-Keplerian orbit fitting. We also explore the spin–orbit dynamics of Haumea and its satellites, showing that axial precession of Hi’iaka may be detectable over decadal timescales. Finally, we present an ephemeris of the Haumea system over the coming decade, enabling high-quality observations of Haumea and its satellites for years to come.
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Gozdźiewski, Krzysztof. „Rotational Dynamics of Janus and Epimetheus“. International Astronomical Union Colloquium 165 (1997): 269–74. http://dx.doi.org/10.1017/s0252921100046662.
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AbstractWe investigate simplified models of flat rotational motion of the coorbital satellites of Saturn, Janus and Epimetheus. We try to verify the hypothesis of chaotic rotation of the moons, caused by gravitational interaction between them. The possibility of parametric resonance in the librations of Janus is also investigated.
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Arifjanov, Aybek, Shamshodbek Akmalov, Shakhzod Shodiev und Abdukarim Haitov. „Discussion of different Remote sensing satellite possibilities for scientifical Earth observations“. E3S Web of Conferences 264 (2021): 04007. http://dx.doi.org/10.1051/e3sconf/202126404007.
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More than 1,000 satellites are launched into space, and they differ in their functions, rotation orbits, resolution, and other properties. Scientists divide the satellites into low-resolution, medium-resolution, high-resolution, and very high-resolution satellites by their properties. Now, the biggest challenge facing scientists is to use some of these different resolution images in their field. To get the expected result, it is very important to analyze the image that needs an which gives more accurate results. Therefore, the main attention of this article is aimed to find the answer to these problems. In this article 3 satellite images which have different resolution are analyzed. The possibility of middle-resolution images of MODIS, high-resolution images of Landsat, and very high-resolution images of WorldView-2 (WV-2) satellites using GIS are analyzed. A research area was the Syrdarya region, and downloaded different images of satellites of this area and compared with using e Cognition. According to the results, a more accurate satellite image for irrigation sets information is WorldView-2 images. In comparison analysis, it shows more accurate properties than other satellite images. As irrigation sets are small objects for the analysis, very high spatial resolution satellite images are important. Water discharge and surface change happen very fast; thus, it requires daily monitoring of the condition. And in this case, the temporal resolution of the MODIS and Landsat is 16 day, and it is a too long period.
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Kozioł, Karol, Andrzej Brosławski, Ashwin Patel, Henri Weisen und Jacek Rzadkiewicz. „Ion temperature spectroscopic measurements in high rotation discharges by means of X-ray diagnostic at JET“. Journal of Instrumentation 17, Nr. 07 (01.07.2022): C07008. http://dx.doi.org/10.1088/1748-0221/17/07/c07008.
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Abstract Measurement of the X-ray spectra of the He-like Ni ions (Ni26+) and their dielectronic satellites (Ni25+, Ni24+, and Ni23+) plays a crucial role in determination of electronic and ion temperature of plasma in the JET device. Because n ⩾ 3 satellites of Ni25+ overlap with resonance line of Ni26+, it is important to reconstruct the structure of these satellites reliably. It is especially important in the cases when plasma rotation is high which may result in an additional broadening of the resonance line. This work is an attempt to identify possible causes of the additional broadening of the resonance line due to the effect of overlapping the dielectronic satellites with the resonance line of Ni26+ and the effect of toroidal plasma rotation shear.
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Zhang, Jie, Pengfei Wu, Qinghu Han, Xin Wei und Yi Duan. „Dynamic Behavior of Satellite and Its Solar Arrays Subject to Large-Scale Antenna Deployment Shock“. Aerospace 11, Nr. 5 (28.04.2024): 349. http://dx.doi.org/10.3390/aerospace11050349.
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Satellites should be equipped with more and more deployable, large, flexible appendages to improve their service efficiency and reduce launch costs. The spring-driven deployment method of flexible appendages has been widely applied and generates great instantaneous shock loads on satellites, maybe affecting the safety of other flexible appendages, but the current related investigations for satellites with multiple large flexible appendages are insufficient. In this study, the deployment test of the antenna itself was conducted, and the attitude changes in a satellite during antenna deployment were telemetered. Then, a related dynamical model of the satellite was established and verified by the telemetry values of the satellite. Finally, the shock mechanism transmitted to solar arrays was analyzed, and the effect of solar array attitude was discussed. The results show that the simulated method of antenna deployment equivalent to the shock loads tested was thought to be efficient, though it could cause a small non-zero constant of the simulated angular velocities in the antenna deployment direction. The shock-induced moments, except the rotation direction of the solar array drive assembly (SADA), should be highlighted for the antenna deployment dynamic design of satellites, and the solar array attitude has few effects on the shock-induced loads at the SADA.
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Yu, Feng, Yi Zhao und Yanhua Zhang. „Pose Determination for Malfunctioned Satellites Based on Depth Information“. International Journal of Aerospace Engineering 2019 (11.06.2019): 1–15. http://dx.doi.org/10.1155/2019/6895628.
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Autonomous on-orbit servicing is the future space activity which can be utilized to extend the satellite life. Relative pose estimation for a malfunctioned satellite is one of the key technologies to achieve robotic on-orbit servicing. In this paper, a relative pose determination method by using point cloud is presented for the final phase of the rendezvous and docking of malfunctioned satellites. The method consists of three parts: (1) planes are extracted from point cloud by utilizing the random sample consensus algorithm. (2) The eigenvector matrix and the diagonal eigenvalue matrix are calculated by decomposing the point cloud distribution matrix of the extracted plane. The eigenvalues are utilized to recognize rectangular planes, and the eigenvector matrix is the attitude rotation matrix from the sensor to the plane. The solution of multisolution problem is also presented. (3) An extended Kalman filter is designed to estimate the translational states, the rotational states, the location of mass center, and the moment-of-inertia ratios. Because the method only utilizes the local features without observing the whole satellite, it is suitable for the final phase of rendezvous and docking. The algorithm is validated by a series of mathematical simulations.
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Noyelles, Benoît. „Theory of the rotation of the Galilean satellites“. Proceedings of the International Astronomical Union 6, S269 (Januar 2010): 240–44. http://dx.doi.org/10.1017/s1743921310007489.
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AbstractAs most of the natural satellites of the Solar System, the Galilean moons are since a long time assumed to be tidally locked in a spin-orbit synchronous resonance. Thanks to the mission Galileo, we now dispose of enough gravity data to perform 3-dimensional theories of the rotation of these satellites, in particular to model the departure from the exact synchronous rotation. We here present such theories depending on the interior model we consider, in highlighting some observable output data. Inverting them will give us information on the internal structure of these bodies.
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Philippe, Robutel, C. M. Correia Alexandre und Leleu Adrien. „Spin-orbit resonances and rotation of coorbital bodies in quasi-circular orbits“. Proceedings of the International Astronomical Union 9, S310 (Juli 2014): 9–12. http://dx.doi.org/10.1017/s1743921314007704.
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AbstractThe rotation of asymmetric bodies in eccentric Keplerian orbits can be chaotic when there is some overlap of spin-orbit resonances. Here we show that the rotation of two coorbital bodies (two planets orbiting a star or two satellites of a planet) can also be chaotic even for quasi-circular orbits around the central body. When dissipation is present, the rotation period of a body on a nearly circular orbit is believed to always end synchronous with the orbital period. Here we demonstrate that for coorbital bodies in quasi-circular orbits, stable non-synchronous rotation is possible for a wide range of mass ratios and body shapes. We further show that the rotation becomes chaotic when the natural rotational libration frequency, due to the axial asymmetry, is of the same order of magnitude as the orbital libration frequency.
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Kumar, K. D., und T. Yasaka. „Rotation Formation Flying of Three Satellites Using Tethers“. Journal of Spacecraft and Rockets 41, Nr. 6 (November 2004): 973–85. http://dx.doi.org/10.2514/1.14251.
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Melnikov, A. V., und I. I. Shevchenko. „The rotation states predominant among the planetary satellites“. Icarus 209, Nr. 2 (Oktober 2010): 786–94. http://dx.doi.org/10.1016/j.icarus.2010.04.022.
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Serebryanskiy, A. V. „SPECTRAL OBSERVATIONS OF GEOSTATIONARY SATELLITES“. Eurasian Physical Technical Journal 19, Nr. 2 (40) (15.06.2022): 93–100. http://dx.doi.org/10.31489/2022no2/93-100.
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One of the main tasks of the situational awareness system in near-Earth space is to determine the type and class of observed objects by analyzing its reflection spectra. This paper proposes a methodology and interpretation of the spectral observational data of geostationary orbit satellites obtained at the Tian Shan Astronomical Observatory (Kazakhstan) from June-December 2021. 8 geostationary objects, the type and design features of which are known were selected as observation targets. The selected satellites are stable (no fast rotation of these objects was detected) and have large reflecting surface areas. An analysis of the obtained reflection spectra shows the dependence on the phase angle of the object. The studies carried out are especially relevant for objects in high orbits, where the only currently available methods of detection and study are ground-based optical photometry and spectroscopy using meter-class telescopes.
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Bloßfeld, Mathis, Julian Zeitlhöfler, Sergei Rudenko und Denise Dettmering. „Observation-Based Attitude Realization for Accurate Jason Satellite Orbits and Its Impact on Geodetic and Altimetry Results“. Remote Sensing 12, Nr. 4 (19.02.2020): 682. http://dx.doi.org/10.3390/rs12040682.
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For low Earth orbiting satellites, non-gravitational forces cause one of the largest perturbing accelerations. During a precise orbit determination (POD), the accurate modeling of the satellite-body attitude and solar panel orientation is important since the satellite’s effective cross-sectional area is directly related to the perturbing acceleration. Moreover, the position of tracking instruments that are mounted on the satellite body are affected by the satellite attitude. For satellites like Jason-1/-2/-3, attitude information is available in two forms—as a so-called nominal yaw steering model and as observation-based (measured by star tracking cameras) quaternions of the spacecraft body orientation and rotation angles of the solar arrays. In this study, we have developed a preprocessing procedure for publicly available satellite attitude information. We computed orbits based on Satellite Laser Ranging (SLR) observations to the Jason satellites at an overall time interval of approximately 25 years, using each of the two satellite attitude representations. Based on the analysis of the orbits, we investigate the influence of using preprocessed observation-based attitude in contrast to using a nominal yaw steering model for the POD. About 75% of all orbital arcs calculated with the observation-based satellite attitude data result in a smaller root mean square (RMS) of residuals. More precisely, the resulting orbits show an improvement in the overall mission RMS of SLR observation residuals of 5.93% (Jason-1), 8.27% (Jason-2) and 4.51% (Jason-3) compared to the nominal attitude realization. Besides the satellite orbits, also the estimated station coordinates benefit from the refined attitude handling, that is, the station repeatability is clearly improved at the draconitic period. Moreover, altimetry analysis indicates a clear improvement of the single-satellite crossover differences (6%, 15%, and 16% reduction of the mean of absolute differences and 1.2%, 2.7%, and 1.3% of their standard deviations for Jason-1/-2/-3, respectively). On request, the preprocessed attitude data are available.
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Strugarek, Dariusz, Krzysztof Sośnica, Daniel Arnold, Adrian Jäggi, Radosław Zajdel, Grzegorz Bury und Mateusz Drożdżewski. „Determination of Global Geodetic Parameters Using Satellite Laser Ranging Measurements to Sentinel-3 Satellites“. Remote Sensing 11, Nr. 19 (30.09.2019): 2282. http://dx.doi.org/10.3390/rs11192282.
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Sentinel-3A/3B (S3A/B) satellites are equipped with a number of precise instruments dedicated to the measurement of surface topography, sea and land surface temperatures and ocean and land surface color. The high-precision orbit is guaranteed by three instruments: Global Positioning System (GPS) receiver, laser retroreflector dedicated to Satellite Laser Ranging (SLR) and Doppler Orbitography and Radiopositioning Integrated by Satellite (DORIS) antenna. In this article, we check the possibility of using SLR observations and GPS-based reduced-dynamic orbits of active S3A/B satellites for the determination of global geodetic parameters, such as geocenter motion, Earth rotation parameters (ERPs) and the realization of the terrestrial reference frame, based on data from 2016-2018. The calculation process was preceded with the estimation of SLR site range biases, different network constraining tests and a different number of orbital arcs in the analyzed solutions. The repeatability of SLR station coordinates based solely on SLR observations to S3A/B is at the level of 8-16 mm by means of interquartile ranges even without network constraining in 7-day solutions. The combined S3A/B and LAGEOS solutions show a consistency of estimated station coordinates better than 13 mm, geocenter coordinates with a RMS of 6 mm, pole coordinates with a RMS of 0.19 mas and Length-of-day with a RMS of 0.07 ms/day when referred to the IERS-14-C04 series. The altimetry observations have to be corrected by the geocenter motion to obtain unbiased estimates of the mean sea level rise. The geocenter motion is typically derived from SLR measurements to passive LAGEOS cannonball-like satellites. We found, however, that SLR observations to active Sentinel satellites are well suited for the determination of global geodetic parameters, such as Earth rotation parameters and geocenter motion, which even further increases the potential applications of Sentinel missions for deriving geophysical parameters.
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Pashkevich, V. V., und A. N. Vershkov. „New High-Precision Values of the Geodetic Rotation of the Mars Satellites System, Major Planets, Pluto, the Moon and the Sun“. Artificial Satellites 54, Nr. 2 (01.06.2019): 31–42. http://dx.doi.org/10.2478/arsa-2019-0004.
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Abstract In this study the relativistic effects (the geodetic precession and the geodetic nutation, which consist of the effect of the geodetic rotation) in the rotation of Mars satellites system for the first time were computed and the improved geodetic rotation of the Solar system bodies were investigated. The most essential terms of the geodetic rotation were computed by the algorithm of Pashkevich (2016), which is applicable to the study of any bodies of the Solar system that have long-time ephemeris. As a result, in the perturbing terms of the physical librations and Euler angles for Mars satellites (Phobos and Deimos) as well as in the perturbing terms of the physical librations for the Moon and Euler angles for major planets, Pluto and the Sun the most significant systematic and periodic terms of the geodetic rotation were calculated. In this research the additional periodic terms of the geodetic rotation for major planets, Pluto and the Moon were calculated.
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Moraes, R. A., G. Borderes-Motta, O. C. Winter und J. Monteiro. „On the stability of additional moons orbiting Kepler-1625 b“. Monthly Notices of the Royal Astronomical Society 510, Nr. 2 (05.01.2022): 2583–96. http://dx.doi.org/10.1093/mnras/stab3576.
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ABSTRACT Since it was proposed, the exomoon candidate Kepler-1625 b-I has changed the way we see satellite systems. Because of its unusual physical characteristics, many questions about the stability and origin of this candidate have been raised. Currently, we have enough theoretical studies to show that if Kepler-1625 b-I is indeed confirmed, it will be stable. Regarding its origin, previous works indicated that the most likely scenario is capture, although conditions for in situ formation have also been investigated. In this work, we assume that Kepler-1625 b-I is an exomoon and study the possibility of an additional, massive exomoon being stable in the same system. To model this scenario, we perform N-body simulations of a system including the planet, Kepler-1625 b-I, and one extra Earth-like satellite. Based on previous results, the satellites in our system will be exposed to tidal interactions with the planet and to gravitational effects owing to the rotation of the planet. We find that the satellite system around Kepler-1625 b is capable of harbouring two massive satellites. The extra Earth-like satellite can be stable in various locations between the planet and Kepler-1625 b-I, with a preference for regions inside $25\, R_{\rm p}$. Our results suggest that the strong tidal interaction between the planet and the satellites is an important mechanism to ensure the stability of satellites in circular orbits closer to the planet, while the 2:1 mean motion resonance between the Earth-like satellite and Kepler-1625 b-I would provide stability for satellites in wider orbits.
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Malkin, Zinovy. „SLR Contribution to Investigation of Polar Motion“. International Astronomical Union Colloquium 178 (2000): 267–76. http://dx.doi.org/10.1017/s0252921100061406.
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AbstractThe Satellite Laser Ranging (SLR) technique has been used to determine Earth Rotation Parameters (ERP) for over twenty years. Most of results contributed to the International Earth Rotation Service (IERS) are based on analysis of observations of Lageos 1 & 2 satellites collected by the global tracking network of about 40 stations. Now five analysis centers submit operational (with 2–15 days delay) solutions and about ten analysis centers contribute yearly final (up to 23 years) ERP series. Some statistics related to SLR observations and analysis are presented and analyzed. Possible problems in SLR observations and analysis and ways of its solution are discussed.
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Chen, Jing, Xiaojun Jin, Cong Hou, Likai Zhu, Zhaobin Xu und Zhonghe Jin. „Real-Time Orbit Determination of Micro–Nano Satellite Using Robust Adaptive Filtering“. Sensors 24, Nr. 24 (14.12.2024): 7988. https://doi.org/10.3390/s24247988.
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Low-performing GPS receivers, often used in challenging scenarios such as attitude maneuver and attitude rotation, are frequently encountered for micro–nano satellites. To address these challenges, this paper proposes a modified robust adaptive hierarchical filtering algorithm (named IARKF). This algorithm leverages robust adaptive filtering to dynamically adjust the distribution of innovation vectors and employs a fading memory weighted method to estimate measurement noise in real time, thereby enhancing the filter’s adaptability to dynamic environments. A segmented adaptive filtering strategy is introduced, allowing for flexible parameter adjustment in different dynamic scenarios. A micro–nano satellite equipped with a miniaturized dual-frequency GPS receiver is employed to demonstrate precise orbit determination capabilities. On-orbit GPS data from the satellite, collected in two specific scenarios—slow rotation and Earth-pointing stabilization—are analyzed to evaluate the proposed algorithm’s ability to cope with weak GPS signals and satellite attitude instability as well as to assess the achievable orbit determination accuracy. The results show that, compared to traditional Extended Kalman Filters (EKF) and other improved filtering algorithms, the IARKF performs better in reducing post-fit residuals and improving orbit prediction accuracy, demonstrating its superior robustness. The three-axes orbit determination internal consistency precision can reach the millimeter level. This work explores a feasible approach for achieving high-performance orbit determination in micro–nano satellites.
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Kolaczek, B. „Rotation of the Solar System Bodies“. Highlights of Astronomy 9 (1992): 508–36. http://dx.doi.org/10.1017/s1539299600009667.
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Solar System bodies are different. They have different sizes, from large planets to small asteroids, and shapes. They have different structure, from solid body to solid body with fluid atmosphere or core, to gaseous bodies, but all of them rotate. The Solar System is a big laboratory for studying rotation of solid and fluid bodies.Different observational methods are applied to determine the rotation of the Solar system bodies. They depend on the position of the observer and on the structure of the bodies. The most accurate methods, laser ranging to the Moon and artificial satellites and Very Long Base radio Interferometry have been applied to the determination of the rotation of the Earth and the Moon. Their accuracy is better than 0.001”, which on the surface of the Earth corresponds to about 3 cm. Radiotracking of artifical satellites have been used for Earth, Moon, Venus, Mars. In the case of Jupiter, Saturn, Uranus, Neptune and Pluto-Charon magnetic and photometric observations have been used respectively. Their accuracy is of the order of one tenth of a degree.