The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
A Bruno - One of the best experts on this subject based on the ideXlab platform.
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trapped proton fluxes at low Earth Orbits measured by the pamela experiment
The Astrophysical Journal, 2015Co-Authors: O Adriani, G C Barbarino, G A Bazilevskaya, R Bellotti, M Boezio, E A Bogomolov, Massimo Bongi, V Bonvicini, S Bottai, A BrunoAbstract:We report an accurate measurement of the geomagnetically trapped proton fluxes for kinetic energy above similar to 70 MeV performed by the PAMELA mission at low Earth Orbits (350 divided by 610 km) ...
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trapped proton fluxes at low Earth Orbits measured by the pamela experiment
arXiv: Earth and Planetary Astrophysics, 2014Co-Authors: O Adriani, G C Barbarino, G A Bazilevskaya, R Bellotti, M Boezio, E A Bogomolov, Massimo Bongi, V Bonvicini, S Bottai, A BrunoAbstract:We report an accurate measurement of the geomagnetically trapped proton fluxes for kinetic energy above > 70 MeV performed by the PAMELA mission at low Earth Orbits (350-610 km). Data were analyzed in the frame of the adiabatic theory of charged particle motion in the geomagnetic field. Flux properties were investigated in detail, providing a full characterization of the particle radiation in the South Atlantic Anomaly region, including locations, energy spectra and pitch angle distributions. PAMELA results significantly improve the description of the Earth's radiation environment at low altitudes placing important constraints on the trapping and interaction processes, and can be used to validate current trapped particle radiation models.
Jihai Jiang - One of the best experts on this subject based on the ideXlab platform.
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flywheel energy storage an upswing technology for energy sustainability
Energy and Buildings, 2007Co-Authors: Haichang Liu, Jihai JiangAbstract:Abstract Flywheel energy storage (FES) can have energy fed in the rotational mass of a flywheel, store it as kinetic energy, and release out upon demand. It is a significant and attractive manner for energy futures ‘sustainable’. The key factors of FES technology, such as flywheel material, geometry, length and its support system were described, which directly influence the amount of energy storage and flywheel specific energy. It is very suitable to such applications that involve many charge–discharge cycles and little in the way of long-term storage applications including International Space Station (ISS), Low Earth Orbits (LEO), overall efficiency improvement and pulse power transfer for Hybrid Electric Vehicles (HEVs), Power Quality (PQ) events, and many stationary applications. Design margins, fault protection and containment were considered as three good approaches to solve safety issue. Vacuum enclosures or helium–air mixture gas condition were discussed for solution of windage energy loss. In short, with the aid of new technologies the cost of FES can be lowered and the FES will play a significant role in securing global energy sustainability.
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flywheel energy storage an upswing technology for energy sustainability
Energy and Buildings, 2007Co-Authors: Jihai JiangAbstract:Abstract Flywheel energy storage (FES) can have energy fed in the rotational mass of a flywheel, store it as kinetic energy, and release out upon demand. It is a significant and attractive manner for energy futures ‘sustainable’. The key factors of FES technology, such as flywheel material, geometry, length and its support system were described, which directly influence the amount of energy storage and flywheel specific energy. It is very suitable to such applications that involve many charge–discharge cycles and little in the way of long-term storage applications including International Space Station (ISS), Low Earth Orbits (LEO), overall efficiency improvement and pulse power transfer for Hybrid Electric Vehicles (HEVs), Power Quality (PQ) events, and many stationary applications. Design margins, fault protection and containment were considered as three good approaches to solve safety issue. Vacuum enclosures or helium–air mixture gas condition were discussed for solution of windage energy loss. In short, with the aid of new technologies the cost of FES can be lowered and the FES will play a significant role in securing global energy sustainability.
O Adriani - One of the best experts on this subject based on the ideXlab platform.
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trapped proton fluxes at low Earth Orbits measured by the pamela experiment
The Astrophysical Journal, 2015Co-Authors: O Adriani, G C Barbarino, G A Bazilevskaya, R Bellotti, M Boezio, E A Bogomolov, Massimo Bongi, V Bonvicini, S Bottai, A BrunoAbstract:We report an accurate measurement of the geomagnetically trapped proton fluxes for kinetic energy above similar to 70 MeV performed by the PAMELA mission at low Earth Orbits (350 divided by 610 km) ...
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trapped proton fluxes at low Earth Orbits measured by the pamela experiment
arXiv: Earth and Planetary Astrophysics, 2014Co-Authors: O Adriani, G C Barbarino, G A Bazilevskaya, R Bellotti, M Boezio, E A Bogomolov, Massimo Bongi, V Bonvicini, S Bottai, A BrunoAbstract:We report an accurate measurement of the geomagnetically trapped proton fluxes for kinetic energy above > 70 MeV performed by the PAMELA mission at low Earth Orbits (350-610 km). Data were analyzed in the frame of the adiabatic theory of charged particle motion in the geomagnetic field. Flux properties were investigated in detail, providing a full characterization of the particle radiation in the South Atlantic Anomaly region, including locations, energy spectra and pitch angle distributions. PAMELA results significantly improve the description of the Earth's radiation environment at low altitudes placing important constraints on the trapping and interaction processes, and can be used to validate current trapped particle radiation models.
Freek Roelofs - One of the best experts on this subject based on the ideXlab platform.
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simulations of m87 and sgr a imaging with the millimetron space observatory on near Earth Orbits
Monthly Notices of the Royal Astronomical Society, 2020Co-Authors: A S Andrianov, A M Baryshev, H Falcke, I A Girin, T De Graauw, V I Kostenko, Volodymyr Kudriashov, V A Ladygin, S F Likhachev, Freek RoelofsAbstract:High resolution imaging of supermassive black holes shadows is a direct way to verify the theory of general relativity at extreme gravity conditions. Very Long Baseline Interferometry (VLBI) observations at millimeter/sub-millimeter wavelengths can provide such angular resolution for supermassive black holes, located in Sgr A* and M87. Recent VLBI observations of M87 with the Event Horizon Telescope (EHT) has shown such capabilities. The maximum obtainable spatial resolution of EHT is limited by Earth diameter and atmospheric phase variations. In order to improve the image resolution longer baselines are required. Radioastron space mission has successfully demonstrated the capabilities of Space-Earth VLBI with baselines much larger than Earth diameter. Millimetron is a next space mission of the Russian Space Agency that will operate at millimeter wavelengths. Nominal orbit of the observatory will be located around Lagrangian L2 point of the Sun-Earth system. In order to optimize the VLBI mode, we consider a possible second stage of the mission that could use near-Earth high elliptical orbit (HEO). In this contribution a set of near-Earth Orbits is used for the synthetic space-ground VLBI observations of Sgr A* and M87 in joint Millimetron and EHT configuration. General-relativistic magnetohydrodynamic models (GRMHD) for black hole environment of Sgr A* and M87 are used for static and dynamic imaging simulations at 230 GHz. A comparison preformed between ground and space-ground baselines demonstrates that joint observations with Millimetron and EHT significantly improve the image resolution and allow the EHT+Millimetron to obtain snapshot images of Sgr A* probing dynamics at fast timescales.
Alessandro Rossi - One of the best experts on this subject based on the ideXlab platform.
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A frequency portrait of Low Earth Orbits
Celestial Mechanics and Dynamical Astronomy, 2019Co-Authors: Giulia Schettino, Alessandro Rossi, Elisa Maria Alessi, Giovanni B. ValsecchiAbstract:In this work, we deepen and complement the analysis on the dynamics of Low Earth Orbits (LEO), carried out by the authors within the H2020 ReDSHIFT project, by characterising the evolution of the eccentricity of a large set of Orbits in terms of the main frequency components. Decomposing the quasi-periodic time series of eccentricity of a given orbit by means of a numerical computation of Fourier transform, we link each frequency signature to the dynamical perturbation which originated it in order to build a frequency chart of the LEO region. We analyse and compare the effects on the eccentricity due to Solar radiation pressure, lunisolar perturbations and high-degree zonal harmonics of the geopotential both in the time and frequency domains. In particular, we identify the frequency signatures due to the dynamical resonances found in LEO, and we discuss the opportunity to exploit the corresponding growth of eccentricity in order to outline decommissioning strategies.
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solar radiation pressure resonances in low Earth Orbits
Monthly Notices of the Royal Astronomical Society, 2018Co-Authors: Elisa Maria Alessi, Alessandro Rossi, Giulia Schettino, G B ValsecchiAbstract:The aim of this work is to highlight the crucial role that orbital resonances associated with solar radiation pressure can have in Low Earth Orbit. We review the corresponding literature, and provide an analytical tool to estimate the maximum eccentricity which can be achieved for well-defined initial conditions. We then compare the results obtained with the simplified model with the results obtained with a more comprehensive dynamical model. The analysis has important implications both from a theoretical point of view, because it shows that the role of some resonances was underestimated in the past, but also from a practical point of view in the perspective of passive deorbiting solutions for satellites at the end-of-life.
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innovative observing strategy and orbit determination for low Earth orbit space debris
Planetary and Space Science, 2012Co-Authors: Andrea Milani, Alessandro Rossi, Davide Farnocchia, L Dimare, F BernardiAbstract:Abstract We present the results of a large scale simulation, reproducing the behavior of a data center for the build-up and maintenance of a complete catalog of space debris in the upper part of the Low Earth Orbits (LEOs) region. The purpose is to determine the performances of a network of advanced optical sensors, through the use of the newest correlation and orbit determination algorithms. This network is foreseen for implementation in a Space Situational Awareness system, such as the future European one. The conclusion is that it is possible to use a network of optical sensors to build up a catalog containing more than 98% of the objects with perigee height between 1100 and 2000 km, which would be observable by a reference radar system selected as comparison. It is also possible to maintain such a catalog within the accuracy requirements motivated by collision avoidance, and to detect catastrophic fragmentation events. The obtained results depend upon specific assumptions on the sensor and on the software technologies.
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Resonant dynamics of Medium Earth Orbits: space debris issues
Celestial Mechanics and Dynamical Astronomy, 2008Co-Authors: Alessandro RossiAbstract:The Medium Earth Orbit region is the home of the navigation constellations. It is shown how the Orbits of these constellations of satellites are strongly affected by the so-called inclination dependent luni-solar resonances. The analytical theory of these resonances is recalled and a large set of numerical integrations is used to investigate the stability of the Orbits of the constellations over very long time spans. The stability issue is important in the definition of possible disposal strategies for the constellation spacecraft, after their end-of-life. Two possible disposal strategies are envisaged involving either stable or unstable Orbits (from the eccentricity growth point of view). In particular it is shown how, to have disposal Orbits with moderately short lifetime (of the orders of 40–50 years), a very large disposal maneuver would be required to rise the inital eccentricity to values above ~ 0.3.
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Collision risk against space debris in Earth Orbits
Celestial Mechanics and Dynamical Astronomy, 2006Co-Authors: Alessandro Rossi, Giovanni B. ValsecchiAbstract:Opik’s formulae for the probability of collision are applied to the analysis of the collision risk against space debris in Low-Earth Orbit (LEO) and Medium Earth Orbit. The simple analytical formulation of Opik’s theory makes it applicable to complex dynamical systems, such as the interaction of the ISS with the whole debris population in LEO The effect of a fragmentation within a multiplane constellation can also be addressed. The analysis of the evolution of the collision risk in Earth orbit shows the need of effective mitigation measures to limit the growth of the collision risk and of the fragmentation debris in the next century.
