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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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