PT5 - GR in the Solar System |
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Speaker |
Lucchesi, David |
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Coauthors |
Lucchesi, David M.; Anselmo, Luciano; Bassan, Massimo; Pardini, Carmen; Peron, Roberto; Pucacco, Giuseppe; Visco, Massimo; |
| Talk Title |
Modeling Non-gravitational Perturbations for Relativistic Measurements with Laser Ranged Satellites and the LARASE experiment |
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Abstract |
Laser ranging to passive satellites represents a way to extract relevant information on Earth’s internal structure, its surface and the way it interacts with the surrounding medium, the atmosphere. Moreover, the precise range measurements of the Satellite Laser Ranging (SLR) technique have allowed to reach significant tests and measurements in gravitational physics, as in the case of gravitomagnetic and gravitoelectric precessions of the orbits of the two LAGEOS satellites and significant constraints on non-Newtonian physics. Therefore, the improvement in the orbit determination of such satellites represents a basilar goal to be reached in order to gain more precise and accurate results in the fields of space geodesy and of fundamental physics. The satellite precise orbit determination (POD) requires two main features: i) high-quality observations and ii) high-quality dynamical models. The availability of high-quality tracking data is provided by the International Laser Ranging Service (ILRS) by means of the very precise SLR technique. With regard to the second issue, a big effort has been done to develop models for the non-gravitational forces on passive satellites, especially for the two LAGEOS with significant results in the literature as already highlighted. However, some of the models built in the past were valid only under particular approximations or simplifications, as for the spin model and the thermal thrust forces, and have not been generalized or tested under different conditions. Further, in order to account for such effects and also to extend/apply the models to the new LARES satellite, new efforts are needed in the field of the non-gravitational forces modeling. The aim of the LARASE (LAser RAnged Satellites Experiment) program is to go a step further in the tests of the gravitational interaction in the field of the Earth by developing high-quality updated models for the perturbing non-gravitational forces. Such an effort is also required in order to provide a reliable error budget with a correct evaluation of the systematic error sources, both gravitational and non-gravitational in their nature. Consequently, we started an activity dedicated to revisit, extend and improve current models for the non-gravitational perturbations in the case of LAGEOS-type satellites. We discuss the spin modeling problem and its intimate relationship with the thermal thrust forces; also the atmospheric drag impact on the orbit will be discussed, especially in the case of LARES due to its much lower altitude with respect to that of the two LAGEOS. Concerning the gravitational perturbations, a comparison among a few models for the background gravitational field will be discussed together with the impact of the tidal errors on the orbits of the satellites. Finally, our recent results on the data analysis of the orbit of the two LAGEOS satellites and of LARES will be shown. |
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