OA@INAFhttps://openaccess.inaf.itThe DSpace digital repository system captures, stores, indexes, preserves, and distributes digital research material.Tue, 21 Sep 2021 11:13:39 GMT2021-09-21T11:13:39Z5091Ambient Vibrations of Age-old Masonry Towers: Results of Long-term Dynamic Monitoring in the Historic Centre of Luccahttp://hdl.handle.net/20.500.12386/30772Title: Ambient Vibrations of Age-old Masonry Towers: Results of Long-term Dynamic Monitoring in the Historic Centre of Lucca
Authors: Azzara, Riccardo Mario; Girardi, Maria; IAFOLLA, Valerio Antonio; LUCCHESI, David; Padovani, Cristina; Pellegrini, Daniele
Tue, 01 Jan 2019 00:00:00 GMThttp://hdl.handle.net/20.500.12386/307722019-01-01T00:00:00ZComprehensive model for the spin evolution of the LAGEOS and LARES satelliteshttp://hdl.handle.net/20.500.12386/28346Title: Comprehensive model for the spin evolution of the LAGEOS and LARES satellites
Authors: VISCO, Massimo; LUCCHESI, David
Abstract: The two L A G E O S and L A R E S are laser-ranged satellites tracked with the best accuracy ever achieved. Using their range measurements many geophysical parameters were calculated and some general relativity effects were directly observed. To obtain precise and refined measurements of the effects due to the predictions of general relativity on the orbit of these satellites, it is mandatory to model with high precision and accuracy all other forces, reducing the free parameters introduced in the orbit determination. A main category of nongravitational forces to be considered are those of thermal origin, whose fine modeling strongly depends on the knowledge of the evolution of the spin vector. We present a complete model, named LASSOS, to describe the evolution of the spin of the L A G E O S and L A R E S satellites. In particular, we solved Euler equations of motion considering not-averaged torques. This is the most general case, and the predictions of the model well fit the available observations of the satellites spin. We also present the predictions of our model in the fast-spin limit, based on the application of averaged equations. The results are in good agreement with those already published, but with our approach we have been able to highlight small errors within these previous works. LASSOS was developed within the LARASE research program. LARASE aims to improve the dynamical model of the two L A G E O S and L A R E S satellites to provide very precise and accurate measurements of relativistic effects on their orbit, and also to bring benefits to geophysics and space geodesy.
Mon, 01 Jan 2018 00:00:00 GMThttp://hdl.handle.net/20.500.12386/283462018-01-01T00:00:00ZGeneral Relativity Measurements in the Field of Earth with Laser-Ranged Satellites: State of the Art and Perspectiveshttp://hdl.handle.net/20.500.12386/30070Title: General Relativity Measurements in the Field of Earth with Laser-Ranged Satellites: State of the Art and Perspectives
Authors: LUCCHESI, David; Anselmo, Luciano; Bassan, Massimo; MAGNAFICO, Carmelo; Pardini, Carmen; PERON, ROBERTO; Pucacco, Giuseppe; VISCO, Massimo
Abstract: Recent results of the LARASE research program in terms of model improvements and
relativistic measurements are presented. In particular, the results regarding the development of
new models for the non-gravitational perturbations that affect the orbit of the LAGEOS and LARES
satellites are described and discussed. These are subtle and complex effects that need a deep
knowledge of the structure and the physical characteristics of the satellites in order to be correctly
accounted for. In the field of gravitational measurements, we present a new measurement of the
relativistic Lense-Thirring precession with a 0.5% precision. In this measurement, together with
the relativistic effect we also estimated two even zonal harmonics coefficients. The uncertainties of
the even zonal harmonics of the gravitational field of the Earth have been responsible, until now,
of the larger systematic uncertainty in the error budget of this kind of measurements. For this
reason, the role of the errors related to the model used for the gravitational field of the Earth in these
measurements is discussed. In particular, emphasis is given to GRACE temporal models, that strongly
help to reduce this kind of systematic errors.
Tue, 01 Jan 2019 00:00:00 GMThttp://hdl.handle.net/20.500.12386/300702019-01-01T00:00:00ZHow to use the Sun–Earth Lagrange points for fundamental physics and navigationhttp://hdl.handle.net/20.500.12386/30102Title: How to use the Sun–Earth Lagrange points for fundamental physics and navigation
Authors: Tartaglia, A.; Lorenzini, E. C.; LUCCHESI, David; Pucacco, G.; Ruggiero, M. L.; Valko, P.
Abstract: We illustrate the proposal, nicknamed LAGRANGE, to use spacecraft, located at the Sun-Earth Lagrange points, as a physical reference frame. Performing time of flight measurements of electromagnetic signals traveling on closed paths between the points, we show that it would be possible: (a) to refine gravitational time delay knowledge due both to the Sun and the Earth; (b) to detect the gravito-magnetic frame dragging of the Sun, so deducing information about the interior of the star; (c) to check the possible existence of a galactic gravitomagnetic field, which would imply a revision of the properties of a dark matter halo; (d) to set up a relativistic positioning and navigation system at the scale of the inner solar system. The paper presents estimated values for the relevant quantities and discusses the feasibility of the project analyzing the behavior of the space devices close to the Lagrange points.
Sun, 01 Jan 2017 00:00:00 GMThttp://hdl.handle.net/20.500.12386/301022017-01-01T00:00:00ZOn the secular decay of the LARES semi-major axishttp://hdl.handle.net/20.500.12386/30104Title: On the secular decay of the LARES semi-major axis
Authors: Pardini, C.; Anselmo, L.; Lucchesi, D.; PERON, ROBERTO
Sun, 01 Jan 2017 00:00:00 GMThttp://hdl.handle.net/20.500.12386/301042017-01-01T00:00:00ZQuantum time delay in the gravitational field of a rotating masshttp://hdl.handle.net/20.500.12386/30075Title: Quantum time delay in the gravitational field of a rotating mass
Authors: Battista, Emmanuele; TARTAGLIA, ANGELO; Esposito, Giampiero; LUCCHESI, David; Ruggiero, Matteo Luca; Valko, Pavol; Dell'Agnello, Simone; Di Fiore, Luciano; Simo, Jules; GRADO, ANIELLO
Abstract: We examine quantum corrections of time delay arising in the gravitational field of a spinning oblate source. Low-energy quantum effects occurring in Kerr geometry are derived within a framework where general relativity is fully seen as an effective field theory. By employing such a pattern, gravitational radiative modifications of Kerr metric are derived from the energy-momentum tensor of the source, which at lowest order in the fields is modelled as a point mass. Therefore, in order to describe a quantum corrected version of time delay in the case in which the source body has a finite extension, we introduce a hybrid scheme where quantum fluctuations affect only the monopole term occurring in the multipole expansion of the Newtonian potential. The predicted quantum deviation from the corresponding classical value turns out to be too small to be detected in the next future, showing that new models should be examined in order to test low-energy quantum gravity within the solar system.
Sun, 01 Jan 2017 00:00:00 GMThttp://hdl.handle.net/20.500.12386/300752017-01-01T00:00:00ZReview and critical analysis of mass and moments of inertia of the LAGEOS and LAGEOS II satellites for the LARASE programhttp://hdl.handle.net/20.500.12386/25949Title: Review and critical analysis of mass and moments of inertia of the LAGEOS and LAGEOS II satellites for the LARASE program
Authors: VISCO, Massimo; LUCCHESI, David
Abstract: The two LAGEOS satellites, currently the best tracked satellites by the stations of the International Laser Ranging Service (ILRS), play a significant role in the fields of space geodesy and geophysics as well as in very precise measurements and constraints in fundamental physics. Specifically, for the measurements of tiny relativistic effects it is mandatory to build accurate models for the dynamics of the satellites, in particular concerning their spin evolution and the determination of their temperature distribution and thermal behavior under different physical conditions. Consequently, an accurate knowledge of both the external and internal structure of the laser-ranged satellites, and of their main dynamic parameters to be used within the orbit models, is of crucial importance. In this work we reconstruct information about the structure, the materials used, and the moments of inertia of the two LAGEOS satellites. The moments of inertia of LAGEOS resulted to be 11.42 ± 0.03 kg m<SUP>2</SUP> for the cylindrical symmetry axis and 10.96 ± 0.03 kg m<SUP>2</SUP> for the other two main axes. The analogous quantities for LAGEOS II are 11.45 ± 0.03 kg m<SUP>2</SUP> and 11.00 ± 0.03 kg m<SUP>2</SUP>. We also built a 3D-CAD model of the satellites structure which is useful for finite element-based analysis. We tried to solve contradictions and overcome several misunderstanding present in the historical literature of the older LAGEOS, carefully reanalyzing the earlier technical papers. To test the results we obtained, we used our moments of inertia to compute the spin evolution of the two satellites obtaining a good agreement between measured and estimated values for the spin direction and the rotational period. We believe we now have accurate knowledge of the mass, moments of inertia, and composition of both LAGEOS satellites.
Fri, 01 Jan 2016 00:00:00 GMThttp://hdl.handle.net/20.500.12386/259492016-01-01T00:00:00ZTesting the gravitational interaction in the field of the Earth via satellite laser ranging and the Laser Ranged Satellites Experiment (LARASE)http://hdl.handle.net/20.500.12386/24042Title: Testing the gravitational interaction in the field of the Earth via satellite laser ranging and the Laser Ranged Satellites Experiment (LARASE)
Authors: LUCCHESI, David; Anselmo, L.; Bassan, M.; Pardini, C.; PERON, ROBERTO; Pucacco, G.; VISCO, Massimo
Abstract: In this work, the Laser Ranged Satellites Experiment (LARASE) is presented. This is a research program that aims to perform new refined tests and measurements of gravitation in the field of the Earth in the weak field and slow motion (WFSM) limit of general relativity (GR). For this objective we use the free available data relative to geodetic passive satellite lasers tracked from a network of ground stations by means of the satellite laser ranging (SLR) technique. After a brief introduction to GR and its WFSM limit, which aims to contextualize the physical background of the tests and measurements that LARASE will carry out, we focus on the current limits of validation of GR and on current constraints on the alternative theories of gravity that have been obtained with the precise SLR measurements of the two LAGEOS satellites performed so far. Afterward, we present the scientific goals of LARASE in terms of upcoming measurements and tests of relativistic physics. Finally, we introduce our activities and we give a number of new results regarding the improvements to the modelling of both gravitational and non-gravitational perturbations to the orbit of the satellites. These activities are a needed prerequisite to improve the forthcoming new measurements of gravitation. An innovation with respect to the past is the specialization of the models to the LARES satellite, especially for what concerns the modelling of its spin evolution, the neutral drag perturbation and the impact of Earth's solid tides on the satellite orbit.
Thu, 01 Jan 2015 00:00:00 GMThttp://hdl.handle.net/20.500.12386/240422015-01-01T00:00:00ZThe LARASE Spin Model of the two LAGEOS and LARES satelliteshttp://hdl.handle.net/20.500.12386/25945Title: The LARASE Spin Model of the two LAGEOS and LARES satellites
Authors: VISCO, Massimo; LUCCHESI, David; Anselmo, Luciano; Bassan, Massimo; MAGNAFICO, Carmelo; Nobili, Anna Maria; Pardini, Carmen; PERON, ROBERTO; Pucacco, Giuseppe; STANGA, RUGGERO
Abstract: Satellite Laser Ranging (SLR) represents a very important technique of the observational space geodesy. In fact, Lunar Laser Ranging, Very Long Baseline Interferometry, Global Navigation Satellite Systems, Doppler Orbitography and Radiopositioning Integrated by Satellite, together with SLR constitute the Global Geodetic Observing System (GGOS). In the context of the GGOS activities, improvements in technology and in modeling will produce advances in Geodesy and Geophysics as well as in General Relativity (GR) measurements. Therefore, these important research fields are not independent, but tightly related to each other. The LARASE (LAser RAnged Satellites Experiment) research program has its main objectives in tests and measurements of Einstein's theory of GR via Precise Orbit Determination (POD) of a set of geodetic satellites. In order to reach such goals by means of very precise measurements of a number of relativistic parameters (and, at the same time, to provide a robust and unassailable error budget of the main systematic effects), we are also reviewing previous models and we are developing new models for the main perturbations (both gravitational and non-gravitational) that act on the orbits of the two LAGEOS and on that of LARES satellites. Within this paper we focus on modeling the spin vector of these satellites. The spin knowledge, both in orientation and rate, is of fundamental importance in order to correctly model the thermal effects acting on the surface of these satellites. These are very important non-gravitational perturbations (NGP) that produce long-term effects on the orbit of the cited satellites, especially for the two LAGEOS, and improvements in their modeling will be very useful both in the field of GR measurements and in those of space geodesy and geophysical applications. Indeed, the current RMS value of the range residuals of the LAGEOS satellites, obtained by the Analysis Centers of the International Laser Ranging Service, is at the level of a few cm since 1992, down to a cm or less during the last years. However, because of the incompleteness in current knowledge of dynamical models, empirical accelerations have been heavily employed to obtain such results. In this context, any step forward in the models developed for the NGP will be useful to reduce the use of empirical accelerations; it also represents an essential prerequisite to reach a sub-mm precision in the RMS of the SLR range residuals and the corresponding benefits in Geophysics and Geodesy, regarding e.g. stations coordinates knowledge, Earth's geocenter and reference frame realization. The paper will focus upon the improvements we obtained with respect on previous models of the spin of the two LAGEOS satellites based on averaged equations for the external torques in the rapid-spin approximation, as well as in a new general model that we developed and based on the solution of the full set of Euler equations.
Fri, 01 Jan 2016 00:00:00 GMThttp://hdl.handle.net/20.500.12386/259452016-01-01T00:00:00Z