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| Euclid Mission Assessment Study - Executive Summary (EADS Astrium) |
| The Euclid Mission Assessment Study is the industrial part of the Euclid assessment phase. The study has been performed by Astrium from September 2008 to September 2009 and is intended for space segment definition and programmatic evaluation. The prime responsibility is with Astrium GmbH (Friedrichshafen, Germany) with support from Astrium SAS (Toulouse, France) and Astrium Ltd (Stevenage, UK). |
| Publication date: 30 Sep 2009 |
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| Technical Review Report - Solar Orbiter |
| Reference: SRE-PA/2009/90 This technical review report for the Solar Orbiter candidate mission presents the outcome of ESA's internal review of this M-class candidate mission in the Cosmic Vision 2015-2025 plan. The review was concluded at the end of the mission assessment phase and carried out in frame of the down-selection to 3 or 4 M-class missions, which will proceed to the definition phase. The main goal of this internal review was to identify the mission's critical issues and associated risks at technical, programmatic and financial level.
Note: This report has been superseded by the Solar Orbiter definition study report (Red Book), released in July 2011, which is linked from the right-hand menu. |
| Publication date: 30 Sep 2009 |
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| Plasma transport in the magnetotail lobes |
| The Earth's magnetosphere is populated by particles originating from the solar wind and the terrestrial ionosphere. A substantial fraction of the plasma from these sources are convected through the magnetotail lobes. In this paper, we present a statistical study of convective plasma transport through the Earth's magnetotail lobes for various geomagnetic conditions. The results are based on a combination of density measurements from the Electric Field and Waves Experiment (EFW) and convection velocities from the Electron Drift Instrument (EDI) on board the Cluster spacecraft. The results show that variations in the plasma flow is primarily attributed to changes in the convection velocity, whereas the plasma density remains fairly constant and shows little correlation with geomagnetic activity. During disturbed conditions there is also an increased abundance of heavier ions, which combined with enhanced convection, cause an accentuation of the mass flow. The convective transport is much slower than the field aligned transport. A substantial amount of plasma therefore escape downtail without ever reaching the central plasma sheet. |
| Publication date: 28 Sep 2009 |
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| On the triggering of auroral substorms by northward turnings of the interplanetary magnetic field |
| Some studies over the last decade have indicated that the instability responsible for substorm expansion phase onset may require an external trigger such as a northward turning of the interplanetary magnetic field (IMF). Statistical investigations have lead to contrasting interpretations regarding the relationship between proposed solar wind triggers and substorm onsets identified from geomagnetic data. We therefore present the results of a study into the possible triggering of 260 substorms between 2001-2005, exploiting data from the Cluster and IMAGE satellite missions. We find that only a small fraction (<25%) of the substorms studied are associated with northward turnings of the IMF. However, the majority of the observed onsets are associated with a growth phase characterised using a subset of the criteria employed to define northward-turning IMF triggers. Based upon a case-by-case investigation and the results of an analysis using the statistics of point processes, we conclude that northward-turning structures in the IMF, while sometimes coinciding with the initial phase of individual substorms, are not required to trigger the magnetospheric instability associated with substorm expansion phase onset. |
| Publication date: 25 Sep 2009 |
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| A mechanism for electrostatic solitary structures in the Earth's magnetosheath |
| Electrostatic solitary waves (ESWs) have been observed in the Earth's magnetosheath region by Cluster. A mechanism for the generation of these structures in terms of electron-acoustic solitons and double layers is discussed. The model simulates the magnetosheath plasma by a four-component plasma system consisting of core electrons, two counterstreaming electron beams, and one type of ions. The analysis is based on the fluid equations and the Poisson equation, and employs the Sagdeev pseudopotential techniques to investigate the solitary waves. The electric field amplitudes, the time durations, and the propagation speeds of the solitary structures predicted by the model are in good agreement with the observed electric fields, pulse widths, and speeds of the electrostatic bipolar pulses. |
| Publication date: 24 Sep 2009 |
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| Marco Polo Assessment Study - Executive Summary Report |
Executive Summary of the mission study by OHB-System AG (Reference: MPL-OHB-TN-014). This executive summary presents the results of the Marco Polo study performed under ESA contract by the industrial team led by OHB-System AG, for an ESA-defined scenario. Possible collaboration schemes associated with this scenario are not addressed here. The results presented address the mission and system design of the ESA space element of the Marco Polo mission including the analysis of critical technologies required for this ambitious mission.
The industrial team was led by OHB-System AG and included the following partners:
- GMV S.A. - focussing on mission analysis and GNC technologies
- Sener S.A. - focussing on landing and sample acquisition technologies
- Aero Sekur S.p.A. - focussing on high speed re-entry technologies
- QinetiQ Ltd - providing consultancy in the area of electric propulsion
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| Publication date: 22 Sep 2009 |
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| Comparison of HIPWAC and Mars Express SPICAM observations of ozone on Mars 2006-2008 and variation from 1993 IRHS observations |
| Ozone is a tracer of photochemistry in the atmosphere of Mars and an observable used to test predictions of photochemical models. We present a comparison of retrieved ozone abundances on Mars using ground-based infrared heterodyne measurements by NASA Goddard Space Flight Center's Heterodyne Instrument for Planetary Wind And Composition (HIPWAC) and space-based Mars Express Spectroscopy for the Investigation of the Characteristics of the Atmosphere of Mars (SPICAM) ultraviolet measurements. Ozone retrievals from simultaneous measurements in February 2008 were very consistent (0.8 micron-atm), as were measurements made close in time (ranging from <1 to >8 micron-atm) during this period and during opportunities in October 2006 and February 2007. The consistency of retrievals from the two different observational techniques supports combining the measurements for testing photochemistry-coupled general circulation models and for investigating variability over the long-term between spacecraft missions. Quantitative comparison with ground-based measurements by NASA/GSFC's Infrared Heterodyne Spectrometer (IRHS) in 1993 reveals 2-4 times more ozone at low latitudes than in 2008 at the same season, and such variability was not evident over the shorter period of the Mars Express mission. This variability may be due to cloud activity. |
| Publication date: 15 Sep 2009 |
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| SPICA Telescope Assessment Study - Executive Summary (EADS Astrium) |
| Reference: INSF.TCN.ASF.SPICA.00021 SPICA is a JAXA led astronomical mission. The ESA contribution to the SPICA mission, mainly entailing the provision of the cryogenic telescope assembly, is a M-class candidate in the Cosmic Vision 2015-2025 Plan.
This document provides a summary of the work performed between August 2008 and September 2009 as part of the SPICA assessment phase study. |
| Publication date: 15 Sep 2009 |
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| An Ultramassive, Fast-Spinning White Dwarf in a Peculiar Binary System |
| White dwarfs typically have masses in a narrow range centered at about 0.6 solar mass (M). Only a few ultramassive white dwarfs (mass > 1.2 M) are known. Those in binary systems are of particular interest, because a small amount of accreted mass could drive them above the Chandrasekhar limit, beyond which they become gravitationally unstable. Using data from the X-ray multimirror mission (XMM)-Newton satellite, we show that the x-ray pulsator RX J0648.0-4418 is a white dwarf with mass > 1.2 M, based on dynamical measurements only. This ultramassive white dwarf in a post-common envelope binary with a hot subdwarf can reach the Chandrasekhar limit, and possibly explode as a type Ia supernova, when its helium-rich companion will transfer mass at an increased rate through Roche lobe overflow. |
| Publication date: 04 Sep 2009 |
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| Untwisting magnetospheres of neutron stars |
| Magnetospheres of neutron stars are anchored in the rigid crust and can be twisted by sudden crustal motions ("starquakes"). The twisted magnetosphere does not remain static and gradually untwists, dissipating magnetic energy and producing radiation. The equation describing this evolution is derived, and its solutions are presented. |
| Publication date: 04 Sep 2009 |
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