LARES succesfully launched in orbit: satellite and mission description

On February 13th 2012, the LARES satellite of the Italian Space Agency (ASI) was launched into orbit with the qualification flight of the new VEGA launcher of the European Space Agency (ESA). The payload was released very accurately in the nominal orbit. The name LARES means LAser RElativity Satellite and summarises the objective of the mission and some characteristics of the satellite. It is, in fact, a mission designed to test Einstein's General Relativity Theory (specifically 'frame dragging' and Lense-Thirring effect). The satellite is passive and covered with optical retroreflectors that send back laser pulses to the emitting ground station. This allows accurate positioning of the satellite, which is important for measuring the very small deviations from Galilei-Newton's laws. In 2008, ASI selected the prime industrial contractor for the LARES system with a heavy involvement of the universities in all phases of the programme, from the design to the construction and testing of the satellite and separation system. The data exploitation phase started immediately after the launch under a new contract between ASI and those universities. Tracking of the satellite is provided by the International Laser Ranging Service. Due to its particular design, LARES is the orbiting object with the highest known mean density in the solar system. In this paper, it is shown that this peculiarity makes it the best proof particle ever manufactured. Design aspects, mission objectives and preliminary data analysis will be also presented.Comment: To appear in Acta Astronautica 201

LARES-lab: a thermovacuum facility for research and e-learning. Tests of LARES satellite components and small payloads for e-learning

LARES, an Italian Space Agency satellite, has been launched successfully in 2012. A small thermovacuum facility has been designed and built specifically for performing tests on the optical components of the satellite. Due to the extremely demanding performances of the optical cube corner reflectors, the space conditions have been simulated using the most up-to-date technology available. In particular Sun, Earth and deep space can be simulated in a ultra high vacuum. It is planned to automate the facility so that it can be operated remotely over the internet. The students during the lectures and the researchers from home will be able to perform thermal tests on specimens by exposing them, for specified amount of time, toward Earth, Sun or deep space. 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 LARES satellite components but will focus mainly to the planned upgrades that improve its remote use both for research and e-learning

The LARES mission: an opportunity to teach general relativity. Frame dragging and Lense-Thirring effect

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 a new satellite specifically designed for testing general relativity

It is estimated that today several hundred operational satellites are orbiting Earth while many more either already re-entered 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 (LAser RElativity Satellite) not only the densest satellite but even the densest known orbiting object in the solar system. That implies the non-gravitational perturbations on its surface will have the smallest effects on its orbit with respect to all other artificial orbiting objects. 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 is passive and covered with 92 retroreflectors. Laser pulses, sent from several ground stations, allow an accurate orbit determination. Along with this last aspect and the mentioned special design one has to take into account the effects of the Earth gravitational perturbations due to the deviation from the spherical symmetry of the gravitational potential. To this aim the latest determinations of the Earth gravitational field, produced using gravitational data from several dedicated space missions including GRACE, and the combination of data from three laser ranged satellites is used in the LARES experiment. In spite of its simplicity LARES was a real engineering challenge both in term of manufacturing and testing. The launch was performed with the VEGA qualification flight provided by the European Space Agency. Data acquisition and processing is 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

An improved mathematical prediction of the time evolution of the Covid-19 pandemic in Italy, with a Monte Carlo simulation and error analyses

We present an improved mathematical analysis of the time evolution of the Covid-19 pandemic in Italy and a statistical error analyses of its evolution, including a Monte Carlo simulation with a very large number of runs to evaluate the uncertainties in its evolution. A previous analysis was based on the assumption that the number of nasopharyngeal swabs would be constant. However, the number of daily swabs is now more than five times what it was when we did our previous analysis. Therefore, here we consider the time evolution of the ratio of the new daily cases to number of swabs, which is more representative of the evolution of the pandemic when the number of swabs is increasing or changing in time. We consider a number of possible distributions representing the evolution of the pandemic in Italy, and we test their prediction capability over a period of up to 6 weeks. The results show that a distribution of the type of Planck black body radiation law provides very good forecasting. The use of different distributions provides an independent possible estimate of the uncertainty. We then consider five possible trajectories for the number of daily swabs and we estimate the potential dates of a substantial reduction in the number of new daily cases. We then estimate the spread in a substantial reduction, below a certain threshold, of the daily cases per swab among the Italian regions. We finally perform a Monte Carlo simulation with 25,000 runs to evaluate a random uncertainty in the prediction of the date of a substantial reduction in the number of diagnosed daily cases per swab

Preliminary study for the measurement of the Lense-Thirring effect with the Galileo satellites

The precession of the orbital node of a particle orbiting a rotating mass is known as Lense-Thirring effect (LTE) and is a manifestation of the general relativistic phenomenon of dragging of inertial frames or frame-dragging. The LTE has already been measured by using the node drifts of the LAGEOS satellites and GRACE-based Earth gravity field models with an accuracy of about 10% and will be improved down to a few percent with the recent LARES experiment. The Galileo system will provide 27 new node observables for the LTE estimation and their combination with the LAGEOS and LARES satellites can potentially reduce even more the error due to the mismodeling in Earth's gravity field. However, the accurate determination of the Galileo orbits requires the estimation of many different parameters, which can absorb the LTE on the orbital nodes. Moreover, the accuracy of the Galileo orbits and hence, of their node drifts, is mainly limited by the mismodeling in the Solar Radiation Pressure (SRP). Using simulated data we analyze the effects of the mismodeling in the SRP on the Galileo nodes and propose optimal orbit parameterizations for the measurement of the LTE from the future Galileo observations

Monitoring systems for pipeline safety based on FBG sensors

Events like earthquakes, landslides, tsunami and other important occurrences, related to human activities could affect heavily the security of the pipeline constructions. Pipeline used for transportation of gas, petroleum and other hydrocarbons could become dangerous for three main problems that can occur during the operation process:1-Explosions related to malfunction of the system itself; 2-defects of the utilized material; 3-Robbery and sabotage operations. In order to prevent these events, the technology needs to step up in the mitigation direction, introducing new systems capable to understand rapidly what is happening in the territory. Those circumstances could constitute a serious and unexpected occurrence, that could afflict a big mass of people in relatively quick time and with catastrophic consequences. Our research group, during these years, has been studying various FBG monitoring systems, for preventing and monitoring among other things these criticalities. The main advantages in using those fibre optic based systems are: high corrosion resistance, no electromagnetic interference, multiplexing capabilities and no need of re-calibration during the years. This paper presents a review of the activities in Sapienza University performed by the Department DICMA and the School of Aerospace Engineering research teams for designing and testing FBG-based vibration sensors that can be used for detecting damaging or illegal activities on pipelines and also for structural monitoring of high pressure pipes

122 Crack growth measurements on a composite specimen using fiber optic sensors

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Testing General Relativity and gravitational physics using the LARES satellite

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. 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

Fundamental Physics and General Relativity with the LARES and LAGEOS satellites

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.Comment: To be publihed in Nuclear Physics. arXiv admin note: substantial text overlap with arXiv:1306.1826, arXiv:1211.137