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.
Highlights
Geodetic satellites, such as the two LAGEOS (LAser GEOdynamic Satellite), represent powerful probes for the study of the Earth’s gravitational field, so to derive significant information on its internal structure, and to test fundamental physics, such as the tiny relativistic precessions that produce secular effects in some of their orbital elements
We introduce and discuss some of the improvements achieved in the development of new models for the main non-gravitational perturbations (NGP) that perturb the orbits of the two LAGEOS [36] satellites as well as that of LARES [37]
The right ascension of the ascending node (RAAN) is the observable to be carefully modelled in the precise orbit determination (POD), being less perturbed by the long-term effects produced by the thermal thrust forces [74,75,121]
Summary
Geodetic satellites, such as the two LAGEOS (LAser GEOdynamic Satellite), represent powerful probes for the study of the Earth’s gravitational field, so to derive significant information on its internal structure, and to test fundamental physics, such as the tiny relativistic precessions that produce secular effects in some of their orbital elements. Laser ranging to Corner Cube Retroreflectors (CCRs) is a technique used since 1964 to track both Earth’s orbiting satellites and the Moon (via the CCRs placed on its surface by the Apollo and Luna missions) It has provided a number of impressive results in the study of both Earth and Moon geophysics, as well as in gravitational physics and in General Relativity (GR). SLR accuracy is currently limited by uncertitude on the satellite centers of mass offset, atmospheric refraction modelling and stations biases Improvements in these fields will allow a sub-mm precision in the RMS of the SLR range measurements with significant benefits in both geophysical and GR measurements.
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