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LARES 2 is an Italian Space Agency (ASI) satellite designed for testing with unprecedented accuracy frame-dragging, a fundamental prediction of general relativity, for other tests of fundamental physics and to contribute to space geodesy with a precision higher than any other satellite presently in orbit. The choice of the material for the body of LARES 2 satellite determines, along with its dimensions, the surface-to-mass ratio minimization, which is the main requirement for the satellite. The paper will report the studies conducted for the fulfillment of the above-mentioned requirement and the tests performed to qualify the materials for construction of the satellite.

Satellite laser-ranging is successfully used in space geodesy, geodynamics and Earth sciences; and to test fundamental physics and specific features of General Relativity. We present a confirmation to approximately one part in a billion of the fundamental weak equivalence principle (uniqueness of free fall) in the Earth's gravitational field, obtained with three laser-ranged satellites, at previously untested range and with previously untested materials. The weak equivalence principle is at the foundation of General Relativity and of most gravitational theories., Comment: 24 pages, 3 figures

Fracture toughness and tensile tests have been carried out on a CuCrZr alloy to characterize its fracture behavior since it is considered a possible candidate for the construction of a passive satellite. Based on the satellite design requirements some copper-based alloys have been studied. These alloys are interesting candidates for the satellite construction because of their physical properties, such as high thermal conductivity and density, and because of their mechanical properties, in fact CuCrZr alloy is age hardenable. The low ductility and toughness of age hardened alloys are not a critical issue for the satellite body, but it could be a problem for the screws. For that reason, the study of the fracture behavior of this alloy is of crucial importance for material selection in the satellite design.

LARES (LAser RElativity Satellite) developed by the Italian Space Agency (ASI) is a laser-ranged satellite successfully launched in February 2012 by ESA (European Space Agency). A second ASI laser-ranged satellite, LARES 2, is scheduled for launch by ESA at the end of 2019. Here we describe the main scientific objectives achieved and achievable by LARES and LARES 2, both in General Relativity and in space geodesy and geodynamics. Among the main tests achieved by LARES is a 5% test of frame-dragging, a fundamental and intriguing prediction of General Relativity. The LARES 2 satellite together with the laser-ranged satellite LAGEOS of NASA, is aimed to provide a 0.2% test of frame-dragging together with other relevant tests and determinations in fundamental physics, space geodesy and geodynamics.

We report the improved test of frame-dragging, an intriguing phenomenon predicted by Einstein's General Relativity, obtained using 7 years of Satellite Laser Ranging (SLR) data of the satellite LARES (ASI, 2012) and 26 years of SLR data of LAGEOS (NASA, 1976) and LAGEOS 2 (ASI and NASA, 1992). We used the static part and temporal variations of the Earth gravity field obtained by the space geodesy mission GRACE (NASA and DLR) and in particular the static Earth's gravity field model GGM05S augmented by a model for the 7-day temporal variations of the lowest degree Earth spherical harmonics. We used the orbital estimator GEODYN (NASA). We measured frame-dragging to be equal to 0.9910 +/- 0.02, where 1 is the theoretical prediction of General Relativity normalized to its frame-dragging value and +/- 0.02 is the estimated systematic error due to modelling errors in the orbital perturbations, mainly due to the errors in the Earth's gravity field determination. Therefore, our measurement confirms the prediction of General Relativity for frame-dragging with a few percent uncertainty., Comment: Submitted on September 27, 2019; accepted for publication on October 8, 2019 and published on October 23, 2019 in The European Physical Journal C: Eur. Phys. J. C (2019) 79:872 https://doi.org/10.1140/epjc/s10052-019-7386-z

In 2016, we published "A test of general relativity using the LARES and LAGEOS satellites and a GRACE Earth gravity model. Measurement of Earth's dragging of inertial frames [1]", a measurement of frame-dragging, a fundamental prediction of Einstein's theory of General Relativity, using the laser-ranged satellites LARES, LAGEOS and LAGEOS 2. The formal error, or precision, of our test was about 0.2% of frame-dragging, whereas the systematic error was estimated to be about 5%. In the 2017 paper "A comment on "A test of general relativity using the LARES and LAGEOS satellites and a GRACE Earth gravity model by I. Ciufolini et al." "by L. Iorio [2] (called I2017 in the following), it was incorrectly claimed that, when comparing different Earth gravity field models, the systematic error in our test due to the Earth's even zonal harmonics of degree 6, 8, 10 could be aslarge as 15%, 6% and 36%, respectively. Furthermore, I2017 contains other, also incorrect, claims about the number of necessary significant decimal digits of the coefficients used in our test (claimed to be nine), in order to eliminate the largest uncertainties in the even zonals of degree 2 and 4, and about the non-repeatability of our test. Here we analyze and rebut those claims in I2017., Comment: Published on The European Physical Journal C 78, no. 11 (2018): 880

The laser-ranging technique and an extremely precise knowledge of the Earth gravitational field paved the way to perform very accurate measurements in General Relativity and Earth science using passive satellites. LARES 2 belongs to this category of satellites and is approved by the Italian Space Agency with a possible launch date at the end of 2019. One of the most interesting effects predicted by General Relativity is frame-dragging according to which the inertial reference frames are dragged by currents of mass-energy, such as a rotating mass. Indeed, the Earth rotation produces this effect that has already been measured by a very accurate orbit determination of the LAGEOS and LARES satellites. With this new satellite it will be possible to improve the accuracy of the measurement by one order of magnitude. This very demanding objective can be reached thanks to the unique orbit and the special design of the LARES 2 satellite. The paper will outline the physics behind the experiment and will describe the mission details.

It is estimated that today several hundred operational satellites are orbiting Earth while many more either have already reentered the atmosphere or are no longer operational. On the 13th of February 2012 one more satellite of the Italian Space Agency has been successfully launched. The main difference with respect to all other satellites is its extremely high density that makes LARES not only the densest satellite but also the densest known orbiting object in the solar system. That implies that the nongravitational perturbations on its surface will have the smallest effects on its orbit. Those design characteristics are required to perform an accurate test of frame dragging and specifically a test of Lense-Thirring effect, predicted by General Relativity. LARES satellite, although passive, with 92 laser retroreflectors on its surface, was a real engineering challenge in terms of both manufacturing and testing. Data acquisition and processing are in progress. The paper will describe the scientific objectives, the status of the experiment, the special feature of the satellite and separation system including some manufacturing issues, and the special tests performed on its retroreflectors.

Earth rotation, besides external actions due to other bodies in the solar system, is influenced by internal mass redistributions, including its atmospheric and water envelope. EI Nifio-Southern Oscillation (ENSO) is one such event characterized by sea level change in the eastern part of the Pacific Ocean due to an increase of the temperature by about 2°C. ENSO is manifested with irreguIar periodicity and with different strength. SateIIite Laser Ranging (SLR) to orbiting satellites such as LAGEOS and LARES in conjunction with the other geodedic techniques, such as GNSS and Very Long Baseline Interferometry (VLBI), allow very accurate determination of the center of mass and rotation vector of the Earth. The paper will report on the experimental vaIues of the Earth orientation parameters and in particuIar of the center of mass and the Iength of the day with particuIar reference to signatures due to last ENSO event ended in 2016.

Global Earth observation for weather forecast and for global environmental monitoring is mainly conducted from space based sensors. The activity of the satellites carrying those instruments is under the risk of impacts from space debris. Protections from hypervelocity impacts can be devised only from debris that are smaller than say 1 cm. For larger sizes the only way to avoid destruction of the spacecraft is to monitor continuously the space around Earth. The observations are conducted from ground based optical observatories and radar stations. By knowing position and orbital parameters of a space debris it is possible to reduce the impact probability by manoeuvring the satellite in advance from the debris predicted orbit. More and more observatories are gaining interest in this area and the "Planetarium and Astronomical Observatory of Gorga" decided recently to start this new activity. An observational campaign is planned for two telescopes available at the observatory. The paper will report the results of the observations.

Laser ranging satellites have proved their efficiency for high precision testing of the effect of frame-dragging, one of remarkable predictions of the General Relativity. The analysis of the randomness properties of the residuals of LAGEOS and LAGEOS 2 satellites reveals the role of the thermal thrust -- Yarkovsky effect -- on the satellite which was in the orbit for longer period (LAGEOS). We also compute Earth's tidal modes affecting the satellite LARES. The recently obtained 5\% accuracy limit reached for the frame dragging effect based on the 3.5 year data of LARES analysed together with those of LAGEOS satellites and using the Earth gravity model of GRACE satellite, is also represented., 7 pages 3 figures

We introduce the LARES 2 space experiment recently approved by the Italian Space Agency (ASI). The LARES 2 satellite is planned for launch in 2019 with the new VEGA C launch vehicle of ASI, ESA and ELV. The orbital analysis of LARES 2 experiment will be carried out by our international science team of experts in General Relativity, theoretical physics, space geodesy and aerospace engineering. The main objectives of the LARES 2 experiment are gravitational and fundamental physics, including accurate measurements of General Relativity, in particular a test of frame-dragging aimed at achieving an accuracy of a few parts in a thousand, i.e., aimed at improving by about an order of magnitude the present state-of-the-art and forthcoming tests of this general relativistic phenomenon. LARES 2 will also achieve determinations in space geodesy. LARES 2 is an improved version of the LAGEOS 3 experiment, proposed in 1984 to measure frame-dragging and analyzed in 1989 by a joint ASI and NASA study., 16 pages

Frame-dragging, one of the outstanding phenomena predicted by General Relativity, is efficiently studied by means of the laser-ranged satellites LARES, LAGEOS and LAGEOS 2. The accurate analysis of the orbital perturbations of Earth’s solid and ocean tides has been relevant for increasing the accuracy in the test of frame-dragging using these three satellites. The Earth’s tidal perturbations acting on the LARES satellite are obtained for the 110 significant modes of corresponding Doodson number and are exhibited to enable the comparison to those of the LAGEOS and LAGEOS-2 satellites. For LARES we represent 29 perturbation modes for l = 2, 3, 4 for ocean tides.

In the previous paper we have introduced the LARES 2 space experiment. The LARES 2 laser-ranged satellite is planned for a launch in 2019 with the new VEGA C launch vehicle of the Italian Space Agency (ASI), ESA and ELV. The main objectives of the LARES 2 experiment are accurate measurements of General Relativity, gravitational and fundamental physics and accurate determinations in space geodesy and geodynamics. In particular LARES 2 is aimed to achieve a very accurate test of frame-dragging, an intriguing phenomenon predicted by General Relativity. Here we report the results of Monte Carlo simulations and covariance analyses fully confirming an error budget of a few parts in one thousand in the measurement of frame-dragging with LARES 2 as calculated in our previous paper., 15 pages and 6 figures. arXiv admin note: text overlap with arXiv:1310.2601

Space debris represent a big concern for future space activities. Particularly at low Earth orbit there is a concentration of debris. Although the probability of impact are today relatively low some occurrences have been registered. The problem was addressed since the beginning of the space age and international treaties regulate the responsibilities of the spacefaring nations. LARES (LAser RElativity Satellite) mission was launched in 2012 and is currently operational. The scientific requirements and the mission design required a waiver to the European debris mitigation regulation for the launch. To date, four close approaches of LARES with space debris have been registered. In the case of a collision with a debris, the resulting controversial is not predictable. The paper addresses possible legal scenarios in case LARES would be involved in an impact with a space debris.

We present a test of General Relativity, the measurement of the Earth's dragging of inertial frames. Our result is obtained using about 3.5 years of laser-ranged observations of the LARES, LAGEOS and LAGEOS 2 laser-ranged satellites together with the Earth's gravity field model GGM05S produced by the space geodesy mission GRACE. We measure $\mu = (0.994 \pm 0.002) \pm 0.05$, where $\mu$ is the Earth's dragging of inertial frames normalized to its General Relativity value, 0.002 is the 1-sigma formal error and 0.05 is the estimated systematic error mainly due to the uncertainties in the Earth's gravity model GGM05S. Our result is in agreement with the prediction of General Relativity.

The use of satellite laser ranging in combination with other space geodetic techniques allows us to determine Earth's motion with unprecedented accuracy, which is not as simple as usually described in basic textbooks. Besides rotation and revolution there is a wobble of the rotation axis that can be derived by the torque free case in rigid body dynamics. The presence of gravitational perturbations complicates the motion and considering Earth as non-rigid introduces even more variations in the basic Earth motion theory. What is interesting is that also the mass redistribution of air and water on the planet can affect the motion of Earth's rotational axis. Thanks to the millimetre accuracy achievable today, it is possible to correlate very small anomalous rotational axis displacements with global environmental changes such the change in ice melting. The paper will show the experimental motion of the Earth rotation axis and interpret it with the use of the Euler rigid body equations of motion, outlining also the effects of the gravitational perturbations of other bodies in the solar system and of the global climate changes on the Earth rotational axis.

In this paper we present a nanosatellite for cosmic ray detection. The main payload is constituted by a particle detector. A second payload may be constituted by the control unit of an innovative type of photovoltaic cells that will have a twofold objective: test the performances and provide additional power to the nanosatellite. It is under investigation the possibility of using a propulsion module in case, later in the phase A study, will be realized an additional advantage to transfer the orbit from circular (the most commonly used in commercial launches) to elliptical. Launch opportunities are relatively frequent since the market of nanosatellites is rapidly increasing and launch providers are including those into their business. The service module will provide power, radio communication, on board computer and attitude control. Thermal control will be achieved passively by the use of paint with proper absorptivity and emissivity and thermal blankets. The problem with this approach is that paint and solar cells have to share the external surface of the nanosatellite, unless a deployable solar array will be included. Besides being an important carrier of information from sources in our galaxy and beyond, cosmic rays may have influence in the terrestrial environment as well as in the technologically advanced human activities, such as orbiting satellites and human spaceflight. The objective of the satellite will be twofold: to train students with hands-on activities through all the phases of a space mission and the development of particle detectors as well as to study the properties of the detected cosmic rays with possible implication in fundamental physics and Earth environmental studies.

A fully equipped thermovacuum facility has been designed and assembled at Sapienza University during the development phase of LARES, a satellite of the Italian Space Agency. After the launch of the satellite in year 2012, the facility has been devoted to testing small payloads and cubesats. An upgrade of the facility allows some operations to be performed remotely. It is planned to complete the automation of the operations so that the majority of the tests could be monitored and controlled from home or during the lectures from the class. The paper will describe the facility, some test campaigns performed recently and the recent advances in remote operations.

We summarize a laser-ranged satellite test of frame-dragging, a prediction of General Relativity, and then concentrate on the estimate of thermal thrust, an important perturbation affecting the accuracy of the test. The frame dragging study analysed 3.5 years of data from the LARES satellite and a longer period of time for the two LAGEOS satellites. Using the gravity field GGM05S obtained via the Grace mission, which measures the Earth's gravitational field, the prediction of General Relativity is confirmed with a 1-$\sigma$ formal error of 0.002, and a systematic error of 0.05. The result for the value of the frame dragging around the Earth is $\mu$ = 0.994, compared to $\mu$ = 1 predicted by General Relativity. The thermal force model assumes heat flow from the sun (visual) and from Earth (IR) to the satellite core and to the fused silica reflectors on the satellite, and reradiation into space. For a roughly current epoch (days 1460 - 1580 after launch) we calculate an average along-track drag of -0.50 $pm/s^{2}$., Comment: 6 pages, multiple figures in Proceedings of Metrology for Aerospace (MetroAeroSpace), 2016 IEEE

The Earth Orientation Parameters (EOP), i.e. the spin axis of the Earth, is influenced by the mass redistribution inside and on the surface of the Earth. On the Earth surface, global ice melting, sea level change and atmospheric circulation are the prime contributors. Recent studies have unraveled the majority of the mysteries behind the Chandler wobble, the annual motion and the secular motion of the pole. The differences from the motion of a pole for a rigid Earth is indeed due to the mass redistribution and transfer of angular momentum among the atmosphere, the oceans and solid Earth. The technique of laser ranging and the use of laser ranged satellites such as LARES along with other techniques such Very Long Baseline Interferometry (VLBI) allow to measure the EOP with accuracies at the level of ~200 μas which correspond to few millimeters at the Earth’s surface, while the use of Global Navigation Satellite System (GNSS) data can reach an accuracy even below 100 μas. At these unprecedented high levels of accuracy, even tiny anomalous behavior in EOP can be observed and thus correlated to global environmental changes such as ice melting on Greenland and the polar caps, and extreme events that involve strong ocean-atmosphere coupling interactions such as the El Nino. The contribution of Satellite Laser Ranging (SLR) data such as from the LARES mission and similar satellites to this area is outlined in this paper.

Satellite Laser Ranging (SLR) makes an important contribution to Earth science providing the most accurate measurement of the long-wavelength components of Earth’s gravity field, including their temporal variations. Furthermore, SLR data along with those from the other three geometric space techniques, Very Long Baseline Interferometry (VLBI), Global Navigation Satellite Systems (GNSS) and DORIS, generate and maintain the International Terrestrial Reference Frame (ITRF) that is used as a reference by all Earth Observing systems and beyond. As a result we obtain accurate station positions and linear velocities, a manifestation of tectonic plate movements important in earthquake studies and in geophysics in general. The “geodetic” satellites used in SLR are passive spheres characterized by very high density, with little else than gravity perturbing their orbits. As a result they define a very stable reference frame, defining primarily and uniquely the origin of the ITRF, and in equal shares, its scale. The ITRF is indeed used as “the” standard to which we can compare regional, GNSS-derived and alternate frames. The melting of global icecaps, ocean and atmospheric circulation, sea-level change, hydrological and internal Earth-mass redistribution are nowadays monitored using satellites. The observations and products of these missions are geolocated and referenced using the ITRF. This allows scientists to splice together records from various missions sometimes several years apart, to generate useful records for monitoring geophysical processes over several decades. The exchange of angular momentum between the atmosphere and solid Earth for example is measured and can be exploited for monitoring global change. LARES, an Italian Space Agency (ASI) satellite, is the latest geodetic satellite placed in orbit. Its main contribution is in the area of geodesy and the definition of the ITRF in particular and this presentation will discuss the improvements it will make in the aforementioned areas.Copyright © 2015 by ASME

The LARES satellite was successfully launched in 2012 for tests of General Relativity and gravitational physics including the accurate measurement of frame-dragging. It is currently very well observed all over the world by the stations of the International Laser Ranging Service. Its preliminary orbital analyses show that LARES behaves as the best artificial massive test particle today available in the solar system, providing an optimal approximation to the time-like geodesic motion of General Relativity. Furthermore, on the basis of a test using almost three years of observations of LARES, we concluded that LARES, together with the LAGEOS and LAGEOS 2 satellites, provides excellent preliminary results for testing General Relativity.

Current observations of the universe have strengthened the interest to further test General Relativity and other theories of fundamental physics. After an introduction to the phenomenon of frame-dragging predicted by Einstein's theory of General Relativity, with fundamental astrophysical applications to rotating black holes, we describe the past measurements of frame-dragging obtained by the LAGEOS satellites and by the dedicated Gravity Probe B space mission. We also discuss a test of String Theories of Chern-Simons type that has been carried out using the results of the LAGEOS satellites. We then describe the LARES space experiment. LARES was successfully launched in February 2012 to improve the accuracy of the tests of frame-dragging, it can also improve the test of String Theories. We present the results of the first few months of observations of LARES, its orbital analyses show that it has the best agreement of any other satellite with the test-particle motion predicted by General Relativity. We finally briefly report the accurate studies and the extensive simulations of the LARES space experiment, confirming an accuracy of a few percent in the forthcoming measurement of frame-dragging., To be publihed in Nuclear Physics. arXiv admin note: substantial text overlap with arXiv:1306.1826, arXiv:1211.1374

LAser RElativity Satellite (LARES) is an Italian Space Agency mission that started operations on February 2012 after a successful launch on ESA's VEGA qualification flight. The satellite is covered with retroreflectors that allow accurate laser ranging tracking from the stations of the International Laser Ranging Service. Data of laser ranged satellites are publicly available for scientific analysis and in the case of LARES are being used mainly for testing general relativity and in particular the Lense-Thirring effect due to the rotation of Earth. Although designed for fundamental physics, the LARES mission is also very useful for geodesy and geodynamics and it will provide, among other things, improvement of the International Terrestrial Reference Frame. After a description of the scientific objectives and of the satellite, the paper will focus on the operations required to run the mission.

LARES was developed under the support of the Italian Space Agency. It has been successfully put in orbit on the 13th February 2012 with the VEGA launcher. The main objective of the LARES mission is to test frame-dragging, with the unprecedented accuracy of about 1%. Frame-dragging is that phenomenon, theorized by General Relativity, such that the currents of mass-energy drag spacetime, in the sense that they drag the inertial frames of reference. It is an intriguing effect that together with gravitational waves and other relativistic predictions is not present in classical Galilei-Newton mechanics. By determining very accurately the orbit of the constellation constituted by LARES and the two LAGEOS satellites, it is possible to achieve such an objective. In fact one of the key issues of the experiment is to have three independent observables that are provided by the three satellites. In the paper it will be shown that the use of the constellation is not the only ingredient required, and in particular LARES needed to be designed at the limit of current technology. Also the most updated and accurate determinations of the gravitational field of Earth are of paramount importance in the test. The paper will describe the main LARES mission components and will show why it is so important the use of a constellation to reach the goal.

LARES is a satellite of the Italian Space Agency, successfully launched with the new VEGA launcher in the occasion of its inaugural flight, VV01. It was put in a circular orbit at 1450 km altitude. This altitude was required to reduce atmospheric drag, whereas the satellite was designed to minimize the non-gravitational perturbations acting on the surface of the satellite. This was of paramount importance because the mission objective is to test Einstein general relativity, and any unmodeled effect could spoil the accuracy of the relativistic measurement. With the optimal design achieved, this non-gravitational unmodeled effects are maintained below 1% of frame-dragging or Lense-Thirring effect. This effect is the orbital node shift induced by the Earth rotation as predicted by general relativity. To achieve the accuracy required for the test, it was conceived a constellation of three laser ranged satellites (LAGEOS 1, LAGEOS 2 and LARES) along with the latest determination of the Earth gravitational field by GRACE satellite. The satellite is a passive system and embedded with 92 Cube Corner Reflectors that have the properties of reflecting back to the emitting ground station the laser pulses, thus allowing its precise orbital determination. In this paper engineering aspects of the mission will be addressed.

LARES is the latest laser ranged geodetic satellite launched in orbit. It is an Italian Space Agency mission devoted mainly to test fundamental physics. However, it will be shown in the present paper that it will also contribute significantly to Earth science. The use of LARES together with the constellation of the other geodetic satellites will provide improvements in the measurement of the gravity field of Earth including its temporal variation measurements. In particular the latter carries signatures of mass redistribution due to several phenomena including global atmospheric and oceanic circulation, useful not only for monitoring global climate change but also to provide a means for climate model validation.

LARES is an Italian Space Agency mission devoted to test frame-dragging, a prediction of general relativity. On February 2012 the satellite has been successfully put in orbit with the qualification flight of VEGA, the new European Space Agency launcher. Basic concepts of general relativity are becoming more and more familiar because of the part they play in science fiction movies. But frame-dragging (more formally known as the Lense-Thirring effect), is so peculiar that it is a relatively unknown effect. The idea of this paper is to start from the description of the experiment and then to push some parameters of the experiment to extreme values in order to magnify the effects of relativity. This approach will provide not only the students and general people but also professionals not strictly specialized in general relativity, with increased interest in gravitational theories.

LARES is an Italian Space Agency satellite specifically designed, built and launched to test general relativity. It is a passive satellite covered with Cube Corner Reflectors that reflect laser pulses from tracking stations, thus allowing accurate measurement of the distance. That in turn enables accurate orbit reconstruction that is a key ingredient to allow the measurement of the tiny Lense-Thirring effect predicted by general relativity. The International Space Time Analysis Research Center provides the International Laser Ranging Service-ILRS, the orbital predictions for LARES for pointing of the tracking telescopes toward the target. The paper describes the technical aspects of generating the orbital predictions.

LARES is an Italian Space Agency mission designed to test General Relativity in the weak field of Earth. In particular, the satellite will be able to measure frame-dragging with an accuracy of about 1%. The difficulty of the measurement is mainly due to the perturbations acting on the satellite and the relatively tiny size of the effect, amounting to about 118 milliarcseconds/year. LARES will also provide data to geodesists and it will contribute to GNSS by improving the origin definition of the International Terrestrial Reference Frame. The mission was designed and the satellite subsystems built and tested in less than four years. The short time to launch and the very limited budget of the LARES mission, raised doubts whether LARES could be, as expected by design, one of the best satellite laser ranging targets. The best way to confirm the success of the mission is to look at the range residuals from the primary stations of the International Laser Ranging Service (ILRS). In the paper it will be shown that from the majority of these stations LARES behaves as the best target.

We present a statistical analysis of the laser ranging data of LAGEOS and LAGEOS 2 satellites which have provided a test of dragging of inertial frames, or frame-dragging, by rotating mass as predicted by General Relativity. As a result, the analysis of the residuals, after filtering out the periodic effects, is consistent with a Gaussian model, with a nonzero mean in agreement with the one predicted by Lense–Thirring effect.

LARES, an Italian Space Agency satellite, has been successfully launched in 2012. A small thermo-vacuum facility has been specifically designed and built for testing the optical components of the satellite in simulated space environment. Due to the extremely demanding performances of LARES satellite, the facility has been built using the most up-to-date technology available. In particular Sun, Earth and deep space can be simulated in a ultra high vacuum. When the tests connected with the LARES mission reduced, it was decided to devote the thermo-vacuum chamber also to didactic activities. The facility was designed to be operated remotely only for some basic operations. The full automation of the facility is in progress in order to provide the students and the researchers with easy and long term access, including also the possibility to operate remotely from the internet and perform complex tests. The students will then have a big opportunity to learn in practice all the aspects of thermo-vacuum testing, which are of paramount importance in the space industry. It will be possible to perform thermal tests from either the classroom or home, by exposing the specimen for a specified amount of time, toward Earth, Sun or deep space simulators. They will collect pressures and temperatures and will input additional thermal power through resistive heaters. The paper will first describe the facility and its capabilities showing the tests performed on the LARES satellite components, then will focus mainly on the planned upgrades that will improve its remote use both for research and e-learning.

The discovery of the accelerating expansion of the Universe, thought to be driven by a mysterious form of “dark energy” constituting most of the Universe, has further revived the interest in testing Einstein’s theory of General Relativity. At the very foundation of Einstein’s theory is the geodesic motion of a small, structureless test-particle. Depending on the physical context, a star, planet or satellite can behave very nearly like a test-particle, so geodesic motion is used to calculate the advance of the perihelion of a planet’s orbit, the dynamics of a binary pulsar system and of an Earth-orbiting satellite. Verifying geodesic motion is then a test of paramount importance to General Relativity and other theories of fundamental physics. On the basis of the first few months of observations of the recently launched satellite LARES, its orbit shows the best agreement of any satellite with the test-particle motion predicted by General Relativity. That is, after modelling its known non-gravitational perturbations, the LARES orbit shows the smallest deviations from geodesic motion of any artificial satellite: its residual mean acceleration away from geodesic motion is less than $\ensuremath 0.5\times10^{-12}$ m/s^2. LARES-type satellites can thus be used for accurate measurements and for tests of gravitational and fundamental physics. Already with only a few months of observation, LARES provides smaller scatter in the determination of several low-degree geopotential coefficients (Earth gravitational deviations from sphericity) than available from observations of any other satellite or combination of satellites.

During the past century Einstein’s theory of General Relativity gave rise to an experimental triumph; however, there are still aspects of this theory to be measured or more accurately tested. Today one of the main challenges in experimental gravitation, together with the direct detection of gravitational waves, is the accurate measurement of the gravitomagnetic field generated by the angular momentum of a body. Here, after a brief introduction on frame-dragging, gravitomagnetism and Lunar Laser Ranging tests, we describe the past measurements of frame-dragging by the Earth spin using the satellites LAGEOS, LAGEOS 2 and the Earth’s gravity models obtained by the GRACE project. We demonstrate that these measurements have an accuracy of approximately 10%. We then describe the LARES experiment to be launched in 2010 by the Italian Space Agency for a measurement of frame-dragging with an accuracy of a few percent. We finally demonstrate that a number of claims by a single individual, that the error budget of the frame-dragging measurements with LAGEOS-LAGEOS 2 and LARES has been underestimated, are indeed ill-founded.

Here we show the first results of the satellite LARES (LAser RElativity Satellite) of the Italian Space Agency, launched in February 2012 by the European Space Agency. Thanks to its special design, LARES minimizes the non-gravitational perturbations and the thermal forces better than any other artificial satellite.

In this paper we respond to the criticisms of "Phenomenology of the Lense-Thirring effect in the Solar System" by lorio et al. about the general relativistic phenomena of gravitomagnetism and frame-dragging. The claims of the paper by lorio et al. are not reproducible in any of our independent analyses. (C) 2011 Elsevier B.V. All rights reserved.

Laser ranging, both Lunar (LLR) and Satellite Laser Ranging (SLR), is one of the most accurate techniques to test gravitational physics and Einstein's theory of General Relativity. Lunar Laser Ranging has provided very accurate tests of both the strong equivalence principle, at the foundations of General Relativity, and of the weak equivalence principle, at the basis of any metric theory of gravity; it has provided strong limits to the values of the so-called PPN (Parametrized Post-Newtonian) parameters, that are used to test the post-Newtonian limit of General Relativity, strong limits to conceivable deviations to the inverse square law for very weak gravity and accurate measurements of the geodetic precession, an effect predicted by General Relativity. Satellite laser ranging has provided strong limits to deviations to the inverse square gravity law, at a different range with respect to LLR, and in particular has given the first direct test of the gravitomagnetic field by measuring the gravitomagnetic shift of the node of a satellite, a frame-dragging effect also called Lense-Thirring effect. Here, after an introduction to gravitomagnetism and frame-dragging, we describe the latest results in measuring the Lense-Thirring effect using the LAGEOS satellites and the latest gravity field models obtained by the space mission GRACE. Finally, we describe an update of the LARES (LAser RElativity Satellite) mission. LARES is planned for launch in 2011 to further improve the accuracy in the measurement of frame-dragging.

In this letter, we reply to the preceding paper by Iorio (EPL, 96 (2011) 30001 (this issue)), hereafter referred to as I2011, where we address criticisms regarding the Lense-Thirring frame-dragging experiment results obtained from the laser ranging to the two LAGEOS satellites. Copyright (C) EPLA, 2011

The LARES space experiment, by the Italian Space Agency (ASI), is based on the launch of a new laser ranged satellite, called LARES (LAser RElativity Satellite), using the new launch vehicle VEGA (Veicolo Europeo di Generazione. Avanzata, provided by ESA). LARES will have an altitude of about 1,450 km, orbital inclination of about 71. 5∘ and nearly zero eccentricity. The LARES satellite together with the satellites LAGEOS (LAser GEOdynamics Satellite launched by NASA) and LAGEOS 2 (built by ASI and launched by NASA and ASI) and with improved GRACE (Gravity Recovery and Climate Experiment, a NASA/DLR, German Space Agency, mission) Earth’s gravity field models will allow a measurement of the Earth’s gravitomagnetic field and of Lense–Thirring effect with an uncertainty of a few percent. After a description of the LARES experiment and of the orbit of LARES, we present an analysis of the main error sources affecting the measurement of gravitomagnetism; these are due to the uncertainties in the Earth’s gravitational field, and in particular to the Earth’s even zonal harmonics, to the time dependent Earth’s gravitational field, and in particular to \dot{J}6 and to the K 1 tide. We also discuss the effect of particle drag and the error due to the uncertainties in the measurement of the orbital inclination. We finally describe some technical and engineering aspects of the LARES mission, and in particular: the laser ranging technique, the cube corner reflectors and the satellite body. We conclude with a brief discussion of LARES separation system and the selected launcher.