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| Wavenumber spectrum of whistler turbulence: Particle-in-cell simulation |
| The forward cascade of decaying whistler turbulence is studied in low beta plasma to understand essential properties of the energy spectrum at electron scales, by using a two-dimensional electromagnetic particle-in-cell (PIC) simulation. This simulation demonstrates turbulence in which the energy cascade rate is greater than the dissipation rate at the electron inertial length. The PIC simulation shows that the magnetic energy spectrum of forward-cascaded whistler turbulence at electron inertial scales is anisotropic and develops a very steep power-law spectrum which is consistent with recent solar wind observations. A comparison of the simulated spectrum with that predicted by a phenomenological turbulence scaling model suggests that the energy cascade at the electron inertial scale depends on both magnetic fluctuations and electron velocity fluctuations, as well as on the whistler dispersion relation. Thus, not only kinetic Alfvén turbulence but also whistler turbulence may explain recent solar wind observations of very steep magnetic spectra at short scales. |
| Publication date: 28 Dec 2010 |
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| SWAP–SECCHI observations of a mass-loading type solar eruption |
| We present a three-dimensional reconstruction of an eruption that occurred on 2010 April 3 using observations from SWAP on board PROBA2 and SECCHI on board STEREO. The event unfolded in two parts: an initial flow of cooler material confined to a height low in the corona, followed by a flux rope eruption higher in the corona. We conclude that mass off-loading from the first part triggered a rise and, subsequently, catastrophic loss of equilibrium of the flux rope. |
| Publication date: 23 Dec 2010 |
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| First measurements of electron vorticity in the foreshock and solar wind |
| We describe the methodology used to set up and compute spatial derivatives of the electron moments using data acquired by the Plasma Electron And Current Experiment (PEACE) from the four Cluster spacecraft. The results are used to investigate electron vorticity in the foreshock. We find that much of the measured vorticity, under nominal conditions, appears to be caused by changes in the flow direction of the return (either reflected or leakage from the magnetosheath) and strahl electron populations as they couple to changes in the magnetic field orientation. This in turn results in deflections in the total bulk velocity producing the measured vorticity. |
| Publication date: 21 Dec 2010 |
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| Direct measurements of the Poynting flux associated with convection electric fields in the magnetosphere |
| Observations of Poynting fluxes associated with onset of convection electric fields are essential for understanding of electromagnetic energy transport from the solar wind toward the magnetosphere leading to changes in the convection electric field, which is one of the most fundamental parameters in the magnetosphere-ionosphere coupled system. We present Cluster multispacecraft observations of Poynting fluxes associated with abrupt changes in large-scale electric fields during sudden commencements and southward turning of the interplanetary magnetic field (IMF). The Cluster spacecraft detected Poynting fluxes dominated by the field-aligned upward component during the preliminary impulse of sudden commencements and in the initial period after southward turning of the IMF. The upward Poynting flux indicates existence of Alfvén waves transporting electromagnetic energy from the ionosphere toward the magnetosphere leading to magnetospheric convection changes. The waveguide model and global magnetohydrodynamic (MHD) simulation calculating evolution of the Poynting flux following solar wind pressure enhancements also show upward Poynting fluxes propagating from the ionosphere toward the magnetosphere faster than the propagation of compressional waves. We conclude that the ionosphere acts as a channel to transmit electromagnetic energy supplied as field-aligned currents toward a wide region in the magnetosphere-ionosphere system instantaneously, leading to changes in magnetospheric convection electric fields. |
| Publication date: 04 Dec 2010 |
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| EChO Mission Proposal |
| EChO is the Exoplanet Characterisation Observatory.
The EChO mission proposal was submitted in 2010 to ESA in response to the Call for medium-size (M-class) missions in the Cosmic Vision 2015-2025 plan with a launch opportunity in the period 2020-22.
In February 2011 EChO was one of four missions recommended by the ESA advisory structure and selected for an assessment study.
The mission proposal can be accessed through the publication link below. |
| Publication date: 03 Dec 2010 |
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| MarcoPolo-R: proposal to ESA in response to call for medium-size missions |
| MarcoPolo-R is a sample return mission to a primitive Near-Earth Asteroid (NEA).
The MarcoPolo-R mission proposal was submitted in 2010 to ESA in response to the Call for medium-size (M-class) missions in the Cosmic Vision 2015-2025 plan with a launch opportunity in the period 2020-22.
In February 2011 MarcoPolo-R was one of four missions recommended by the ESA advisory structure and selected for an assessment study.
The mission proposal can be accessed through the publication link below.
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| Publication date: 03 Dec 2010 |
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| STE-QUEST Mission Proposal |
| STE-QUEST is the Space-Time Explorer and Quantum Equivalence Principle Space Test.
The STE-QUEST mission proposal was submitted in 2010 to ESA in response to the Call for medium-size (M-class) missions in the Cosmic Vision 2015-2025 plan with a launch opportunity in the period 2020-22.
In February 2011 STE-QUEST was one of four missions recommended by the ESA advisory structure and selected for an assessment study.
The mission proposal can be accessed through the publication link below. |
| Publication date: 03 Dec 2010 |
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| Announcement of Opportunity: ExoMars Entry, Descent and Landing Demonstrator Module Science |
The main document for the Announcement of Opportunity for ExoMars Entry, Descent and Landing Demonstrator Module Science |
| Publication date: 29 Nov 2010 |
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| EDM Surface Payload Experiment - Proposal Information Package (E-PIP) |
Technical, managerial and programmatic data relevant to the Announcement of Opportunity for the Surface Payload on the ExoMars Entry, Descent and Landing Demonstrator Module |
| Publication date: 29 Nov 2010 |
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| Cassini finds an oxygen–carbon dioxide atmosphere at Saturn’s icy moon Rhea |
| The flyby measurements of the Cassini spacecraft at Saturn's moon Rhea reveal a tenuous oxygen-carbon dioxide atmosphere. The atmosphere appears to be sustained by chemical decomposition of the surface water ice under irradiation from Saturn's magnetospheric plasma. This in situ detection of an oxidizing atmosphere is consistent with remote observations of other icy bodies such as Jupiter's moons Europa and Ganymede, and suggestive of a reservoir of radiolytic O2 locked within Rhea's ice. The presence of CO2 suggests radiolysis reactions between surface oxidants and organics, or sputtering and/or outgassing of CO2 endogenic to Rhea's ice. Observations of outflowing positive and negative ions give evidence for pickup ionization as a major atmospheric loss mechanism. |
| Publication date: 26 Nov 2010 |
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| Statistical study of the quasi-perpendicular shock ramp widths |
| The width of the collisionless shock front is one of the key shock parameters. The width of the main shock transition layer is related to the nature of the collisionless process that balances nonlinearity and therefore leads to the formation of the shock itself. The shock width determines how the incoming plasma particles interact with the macroscopic fields within the front and, therefore, the processes that result in the energy redistribution at the front. Cluster and Themis measurements at the quasi-perpendicular part of the terrestrial bow shock are used to study the spatial scale of the magnetic ramp. It is shown that statistically the ramp spatial scale decreases with the increase of the shock Mach number. This decrease of the shock scale together with previously observed whistler packets in the foot of supercritical quasi-perpendicular shock indicates that it is the dispersion that determines the size of magnetic ramp even for supercritical shocks. |
| Publication date: 18 Nov 2010 |
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| Big year for small satellite - ESA's second in-orbit technology demonstrator mission: PROBA-2 |
| Less than a cubic metre in volume, PROBA-2 is one of the smallest missions ever flown by ESA. But judged by performance per kilogram, PROBA-2 can also claim to be among the most scientifically and technically productive. |
| Publication date: 15 Nov 2010 |
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| Monopolar and bipolar auroral electric fields and their effects |
| Most of the high-altitude auroral electric fields observed by CLUSTER can be classified into monopolar and bipolar structures. The observations associate monopolar electric fields with polar cap boundary arcs, while bipolar fields tend to be linked to discrete arcs within the auroral oval and to polar cap arcs. The present paper proposes an explanation for this association based on a simple model of the magnetotail configuration and kinetic model computations. The paper introduces a quasi-electrostatic model to describe the auroral current system associated with monopolar and bipolar high-altitude fields. Analytic solutions are presented. The model gives indications about the location of the up- and downward field-aligned current regions, the ionospheric and magnetospheric convection along the arc, the acceleration or deceleration of precipitating particles, and the behaviour of escaping ionospheric ions. |
| Publication date: 09 Nov 2010 |
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| The Detection of a Population of Submillimeter-Bright, Strongly-Lensed Galaxies |
| Gravitational lensing is a powerful astrophysical and cosmological probe and is particularly valuable at submillimeter wavelengths for the study of the statistical and individual properties of dusty star-forming galaxies. However, the identification of gravitational lenses is often time-intensive, involving the sifting of large volumes of imaging or spectroscopic data to find few candidates. We used early data from the Herschel Astrophysical Terahertz Large Area Survey to demonstrate that wide-area submillimeter surveys can simply and easily detect strong gravitational lensing events, with close to 100% efficiency. |
| Publication date: 05 Nov 2010 |
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| Early star-forming galaxies and the reionization of the Universe |
| Star-forming galaxies trace cosmic history. Recent observational progress with the NASA Hubble Space Telescope has led to the discovery and study of the earliest known galaxies, which correspond to a period when the Universe was only ~800 million years old. Intense ultraviolet radiation from these early galaxies probably induced a major event in cosmic history: the reionization of intergalactic hydrogen. |
| Publication date: 04 Nov 2010 |
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| Electron Physics of Asymmetric Magnetic Field Reconnection |
| There have been many significant advances in understanding magnetic field reconnection as a result of improved space measurements and two-dimensional computer simulations. While reviews of recent work have tended to focus on symmetric reconnection on ion and larger spatial scales, the present review will focus on asymmetric reconnection and on electron scale physics involving the reconnection site, parallel electric fields, and electron acceleration. |
| Publication date: 03 Nov 2010 |
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European Space Agency
Robotic Exploration Technology Plan
Programme of Work 2009-2014 (November 2010) |
Your local settings prevented this page from automatically redirecting to the page with the publication's details. To go to the publication page, please click here.
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| Publication date: 01 Nov 2010 |
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| Radioactive 26Al from the Scorpius-Centaurus association |
Context. The Scorpius-Centaurus association is the most-nearby group of massive and young stars. As nuclear-fusion products are ejected by massive stars and supernovae into the surrounding interstellar medium, the search for characteristic g-rays from radioactivity is one way to probe the history of activity of such nearby massive stars on a My time scale through their nucleosynthesis. 26Al decays with a radioactivity lifetime t~1 My, 1809 keV g-rays from its decay can be measured with current g-ray telescopes. |
| Publication date: 01 Nov 2010 |
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| Photolysis of sulphuric acid as the source of sulphur oxides in the mesosphere of Venus |
| The sulphur cycle plays fundamental roles in the chemistry and climate of Venus. Thermodynamic equilibrium chemistry at the surface of Venus favours the production of carbonyl sulphide and to a lesser extent sulphur dioxide. These gases are transported to the middle atmosphere by the Hadley circulation cell. Above the cloud top, a sulphur oxidation cycle involves conversion of carbonyl sulphide into sulphur dioxide, which is then transported further upwards. A significant fraction of this sulphur dioxide is subsequently oxidized to sulphur trioxide and eventually reacts with water to form sulphuric acid. Because the vapour pressure of sulphuric acid is low, it readily condenses and forms an upper cloud layer at altitudes of 60-70 km, and an upper haze layer above 70 km (ref. 9), which effectively sequesters sulphur oxides from photochemical reactions. Here we present simulations of the fate of sulphuric acid in the Venusian mesosphere based on the Caltech/JPL kinetics model, but including the photolysis of sulphuric acid. Our model suggests that the mixing ratios of sulphur oxides are at least five times higher above 90 km when the photolysis of sulphuric acid is included. Our results are inconsistent with the previous model results but in agreement with the recent observations using ground-based microwave spectroscopy and by Venus Express. |
| Publication date: 31 Oct 2010 |
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| Planck pre-launch status: The Planck mission |
A&A doi http://dx.doi.org/10.1051/0004-6361/200912983
The Planck mission was conceived in 1992, in the wake of the release of the results from the Cosmic Background Explorer (COBE) satellite (Boggess et al. 1992), notably the measurement by the FIRAS instrument of the shape of the spectrum of the Cosmic Microwave Background (CMB), and the detection by the DMR instrument of the spatial anisotropies of the temperature of the CMB. The latter result in particular led to an explosion in the number of ground-based and suborbital experiments dedicated to mapping of the anisotropies, and to proposals for space experiments both in Europe and the USA. |
| Publication date: 27 Oct 2010 |
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