LARES successfully launched in orbit: Satellite and mission description

Paolozzi, Antonio; Ciufolini, Ignazio

doi:10.1016/j.actaastro.2013.05.011

Cited by 56 publications

(38 citation statements)

References 38 publications

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“…This value, and all values for the orbital parameters for the first 126 days are taken from [16]. The satellite was successfully launched in orbit on February 13, 2012 at 10:00 UTC from the European Space Agency's spacesport in Kourou, French Guyana [17]. To describe the orbit, we will work in celestial coordinate system 4 .…”

Section: Orbital Geometrymentioning

confidence: 99%

Modelling LARES temperature distribution and thermal drag

Nguyen¹,

Matzner²

2015

Eur. Phys. J. Plus

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Abstract. The LARES satellite, a laser-ranged space experiment to contribute to geophysics observation, and to measure the general relativistic Lense-Thirring effect, has been observed to undergo an anomalous along-track orbital acceleration of -0.4 pm/s 2 (pm := picometer). This thermal "drag" is not surprising; along track thermal drag has previously been observed with the related LAGEOS satellites (-3.4 pm/s 2 ). It is hypothesized that the thermal drag is principally due to anisotropic thermal radiation from the satellite's exterior. We report the results of numerical computations of the along-track orbital decay of the LARES satellite during the first 126 days after launch. The results depend to a significant degree on the visual and IR absorbance α and emissivity of the fused silica Cube Corner Reflectors. We present results for two values of αIR = IR: 0.82, a standard number for "clean" fused silica; and 0.60, a possible value for silica with slight surface contamination subjected to the space environment. The heating and the resultant along-track acceleration depend on the plane of the orbit, the sun position, and in particular on the occurrence of eclipses, all of which are functions of time. Thus we compute the thermal drag for specific days. We compare our model to observational data, available for a 120-day period starting with the 7th day after launch, which shows the average acceleration of -0.4 pm/s 2 . With our model the average along-track thermal drag over this 120-day period for CCR αIR = IR = 0.82 was computed to be -0.59 pm/s 2 . For CCR αIR = IR = 0.60 we compute -0.36 pm/s 2 . LARES consists of a solid spherical tungsten sphere, into which the CCRs are set in colatitude circles. Our calculation models the satellite as 93 isothermal elements: the tungsten part, and each of the 92 Cube Corner Reflectors. The satellite is heated from two sources: sunlight and Earth's infrared (IR) radiation. We work in the fast-spin regime, where CCRs with the same colatitude can be taken to have the same temperature. Since all temperature variations (temporal or spatial) are expected to be small, we linearize the Stefan-Boltzmann law and, taking advantage of the linearity, we perform a Fourier series analysis. The variations are indeed small, validating our Fourier analysis.

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Section: Orbital Geometrymentioning

confidence: 99%

Modelling LARES temperature distribution and thermal drag

Nguyen¹,

Matzner²

2015

Eur. Phys. J. Plus

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“…All satellites, with the exception of Ajisai, are characterised by small area-to-mass ratios which reduce non-gravitational perturbations such as SRP and atmospheric drag. In particular, the area-to-mass ratio of LARES is approximately 2.6 times lower than that of each LAGEOS satellite, making LARES the densest known object in the Solar System (Paolozzi and Ciufolini 2013). Apart from atmospheric drag, the non-gravitational perturbations experienced by the orbit of LARES are typically the smallest in magnitude among all satellites.…”

Section: Collinearity Diagnosis In Geodetic Data Analysismentioning

confidence: 99%

Collinearity assessment of geocentre coordinates derived from multi-satellite SLR data

Spatar

Moore

Clarke

2015

J Geod

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Of the three satellite geodetic techniques contributing to the International Terrestrial Reference Frame (ITRF), Satellite Laser Ranging (SLR) is generally held to provide the most reliable time series of geocentre coordinates and exclusively defines the ITRF origin. Traditionally, only observations to the two LAser GEOdynamics Satellite (LAGEOS) and Etalon pairs of satellites have been used for the definition of the ITRF origin. Previous simulation studies using evenly sampled LAGEOS-like data have shown that only the Z component of geocentre motion suffers minor collinearity issues, which may explain its lower quality compared to the equatorial components. Using collinearity diagnosis, this study provides insight into the actual capability of SLR to sense geocentre motion using the existing geographically unbalanced ground network and real observations to eight spherical geodetic satellites. We find that, under certain parameterisations, observations to the low Earth orbiters (LEOs) Starlette, Stella, Ajisai and LAser RElativity Satellite (LARES) are able to improve the observability of the geocentre coordinates in multi-satellite solutions compared to LAGEOS-only solutions. The higher sensitivity of LEOs to geocentre motion and the larger number of observations are primarily responsible for the improved observability. Errors in the modelling of Starlette, Stella and Ajisai orbits may contaminate the geocentre motion estimates, but do not disprove the intrinsic strength of LEO tracking data. The sporadically observed Etalon satellites fail to make a significant beneficial contribution to the observability of the geocentre coordinates derived via the network shift approach and can be safely omitted from SLR

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“…These satellites are spherical in shape, fully passive, and with a generally low area-to-mass ratio in order to minimize the non-gravitational accelerations. In particular, LARES is the densest object ever launched by the man in space, with an area-to-mass ratio 2.6 times smaller than that of the two LAGEOS satellites 9,10 . Concerning the measurements to be performed, LARASE will mainly focus on the relativistic precessions related with the Earth's gravitoelectric and gravitomagnetic fields.…”

Section: Larase Goals and Gr Relativistic Precessionsmentioning

confidence: 99%

Testing gravitation with satellite laser ranging and the LARASE experiment

Lucchesi¹,

Anselmo²,

Bassan³

et al. 2017

The Fourteenth Marcel Grossmann Meeting

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The International Laser Ranging Service (ILRS) provides range measurements of passive satellites around the Earth through the powerful Satellite Laser Ranging (SLR) technique. These very precise measurements of the distance between an on-ground laser station and a satellite equipped with cube corner retro-reflectors (CCRs) make possible precise tests and measurements in fundamental physics and, in particular, in gravitational physics. The LAGEOS (NASA 1976) and LAGEOS II (NASA/ASI 1992) satellites are outstanding examples of very good test particles because of their very low area-to-mass ratio as well as the high quality of their tracking data and, consequently, of the precise orbit determination (POD) we can obtain after a refined modeling of their orbit. The aim of our research program LARASE (LAser RAnged Satellites Experiment) is to go a step further in testing gravitation in the field of Earth by means of the joint analysis of the orbits of the two LAGEOS satellites together with that of the most recently launched LARES (ASI, 2012) satellite. Therefore, our work falls in the so-called weak field and slow motion (WFSM) limit of Einstein's general relativity (GR) where, in terms of Newtonian physics, relativistic effects appear as two new fields to be added to the classical gravitational field: the gravitoelectric and the gravitomagnetic fields. A fundamental ingredient to reach such a goal is to provide high-quality updated models for the perturbing non-gravitational perturbations (NGP) acting on the surface of these satellites. In fact, regardless of their minimization thanks to a smaller value for the area-to-mass ratio, the subtle and complex to model perturbing effects of the NGP play a crucial role in the POD of the considered satellites, especially in the case of the thermal thrust effects. A large amount of SLR data of LAGEOS and LAGEOS II has been worked out using a set of dedicated models for the satellite dynamics and the related post-fit residuals have been analyzed. A parallel work was performed with LARES, although at a preliminary stage. Our recent work on the orbit modeling and on the data analysis of the orbit of such satellites is presented and discussed.

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LARES successfully launched in orbit: Satellite and mission description

Cited by 56 publications

References 38 publications

Modelling LARES temperature distribution and thermal drag

Modelling LARES temperature distribution and thermal drag

Collinearity assessment of geocentre coordinates derived from multi-satellite SLR data

Testing gravitation with satellite laser ranging and the LARASE experiment

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