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835 results on '"HELIOS - LATMOS"'

201. Wide-banded NTC radiation: local to remote observations by the four Cluster satellites

Author

I. Galkina, Fabien Darrouzet, P. Canu, A. Denazelle, P. M. E. Décréau, Jean-Louis Rauch, S. Rochel Grimald, F. El-Lemdani Mazouz, S. Aoutou, X. Vallières, Laboratoire de Physique et Chimie de l'Environnement et de l'Espace (LPC2E), Observatoire des Sciences de l'Univers en région Centre (OSUC), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Centre National d’Études Spatiales [Paris] (CNES), Laboratoire de Physique des Plasmas (LPP), Université Paris-Sud - Paris 11 (UP11)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-École polytechnique (X)-Sorbonne Université (SU)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), ONERA / DPHY, Université de Toulouse [Toulouse], ONERA-PRES Université de Toulouse, HELIOS - LATMOS, Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Belgian Institute for Space Aeronomy / Institut d'Aéronomie Spatiale de Belgique (BIRA-IASB), Université Paris-Saclay-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris-Sud - Paris 11 (UP11)-École polytechnique (X)-Observatoire de Paris, and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)

Subjects
Atmospheric Science, 010504 meteorology & atmospheric sciences, Plasmasphere, Plasma oscillation, 01 natural sciences, Electromagnetic radiation, Earth radius, Spectral line, Optics, [PHYS.PHYS.PHYS-PLASM-PH]Physics [physics]/Physics [physics]/Plasma Physics [physics.plasm-ph], Electric field, 0103 physical sciences, Earth and Planetary Sciences (miscellaneous), lcsh:Science, 010303 astronomy & astrophysics, 0105 earth and related environmental sciences, Physics, business.industry, lcsh:QC801-809, Geology, Astronomy and Astrophysics, lcsh:QC1-999, [PHYS.PHYS.PHYS-SPACE-PH]Physics [physics]/Physics [physics]/Space Physics [physics.space-ph], Computational physics, lcsh:Geophysics. Cosmic physics, Space and Planetary Science, lcsh:Q, Satellite, business, lcsh:Physics, Radio wave
Abstract

The Cluster multi-point mission offers a unique collection of non-thermal continuum (NTC) radio waves observed in the 2–80 kHz frequency range over almost 15 years, from various view points over the radiating plasmasphere. Here we present rather infrequent case events, such as when primary electrostatic sources of such waves are embedded within the plasmapause boundary far from the magnetic equatorial plane. The spectral signature of the emitted electromagnetic waves is structured as a series of wide harmonic bands within the range covered by the step in plasma frequency encountered at the boundary. Developing the concept that the frequency distance df between harmonic bands measures the magnetic field magnitude B at the source (df = Fce, electron gyrofrequency), we analyse three selected events. The first one (studied in Grimald et al., 2008) presents electric field signatures observed by a Cluster constellation of small size (~ 200 to 1000 km spacecraft separation) placed in the vicinity of sources. The electric field frequency spectra display frequency peaks placed at frequencies fs = n df (n being an integer), with df of the order of Fce values encountered at the plasmapause by the spacecraft. The second event, taken from the Cluster tilt campaign, leads to a 3-D view of NTC waves ray path orientations and to a localization of a global source region at several Earth radii (RE) from Cluster (Décréau et al., 2013). The measured spectra present successive peaks placed at fs ~ (n+ 1/2) df. Next, considering if both situations might be two facets of the same phenomenon, we analyze a third event. The Cluster fleet, configured into a constellation of large size (~ 8000 to 25 000 km spacecraft separation), allows us to observe wide-banded NTC waves at different distances from their sources. Two new findings can be derived from our analysis. First, we point out that a large portion of the plasmasphere boundary layer, covering a large range of magnetic latitudes, is radiating radio waves. The radio waves are issued from multiple sources of small size, each related to a given fs series and radiating inside a beam of narrow cone angle, referred to as a beamlet. The beamlets illuminate different satellites simultaneously, at different characteristic fs values, according to the latitude at which the satellite is placed. Second, when an observing satellite moves away from its assumed source region (the plasmapause surface), it is illuminated by several beamlets, issued from nearby sources with characteristic fs values close to each other. The addition of radio waves blurs the spectra of the overall received electric field. It can move the signal peaks such that their position fs satisfiesfs = (n+α) df, with 0 < α < 1. These findings open new perspectives for the interpretation of NTC events displaying harmonic signatures.

Published
2015

202. Cusp dynamics under northward IMF using three‐dimensional global particle‐in‐cell simulations

Author

Bertrand Lembège, Amin Esmaeili, Ken-Ichi Nishikawa, Dongsheng Cai, Université de Tsukuba = University of Tsukuba, HELIOS - LATMOS, Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), National Space Science and Technology Center (NSSTC), and NASA Marshall Space Flight Center (MSFC)-University of Alabama in Huntsville (UAH)

Subjects
Particle simulation, Magnetic cusp, 010504 meteorology & atmospheric sciences, [SDU.STU.GP]Sciences of the Universe [physics]/Earth Sciences/Geophysics [physics.geo-ph], Cluster mission, Magnetosphere, Stagnant exterior cusp, Context (language use), Plasma depletion layer, 01 natural sciences, 0103 physical sciences, Interplanetary magnetic field, 010303 astronomy & astrophysics, 0105 earth and related environmental sciences, Cusp (singularity), Physics, Computer simulation, [PHYS.PHYS.PHYS-SPACE-PH]Physics [physics]/Physics [physics]/Space Physics [physics.space-ph], Alfvén transition layer, Computational physics, Solar wind, Geophysics, Classical mechanics, Space and Planetary Science, Physics::Space Physics, Particle-in-cell, Magnetohydrodynamics
Abstract

International audience; The interaction of the solar wind with the terrestrial magnetosphere is analyzed with the help of three-dimensional (3-D) global, full-electromagnetic particle-in-cell (PIC) simulations, in the configuration where the interplanetary magnetic field (IMF) is steadily northward. The present study is mainly focused on the cusp region and associated particle momenta dynamics. Within the present context and to the best of our knowledge, this work represents the first numerical simulation for analyzing the cusp dynamics using a fully self-consistent 3-D kinetic and electromagnetic approach. The main goals of the study are the following: (i) to retrieve the main known features of the cusp to validate the use of 3-D PIC “global” simulations, (ii) to compare with previous results obtained with 3-D MHD simulations, (iii) to create an updated global view of the cusp based on use of 3-D PIC simulation, which cannot be obtained from a MHD approach, and (iv) to compare with statistical results from the Cluster mission. In particular, the stagnant exterior cusp (SEC) identified in previous statistical analysis of experimental data is retrieved, and it is possible to more precisely define the edges of the SEC region. In addition, we will focus on cusp features recently observed by the Cluster mission, for example, the Alfvén Transition Layer or ATL and on the features not reproduced by either MHD or the hybrid approach, which have been used to characterize the outer edges of the cusp more clearly.

Published
2015

203. Voyager 1/UVS Lyman α Measurements at the Distant Heliosphere (90–130 AU): Unknown Source of Additional Emission

Author

Vladislav Izmodenov, Bill R. Sandel, Rosine Lallement, Eric Quémerais, Olga Katushkina, Space Research Institute of the Russian Academy of Sciences (IKI), Russian Academy of Sciences [Moscow] (RAS), HELIOS - LATMOS, Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Faculty of Mechanics and Mathematics [Moscow], Lomonosov Moscow State University (MSU), institute for Problems in Mechanics [Moscow], Galaxies, Etoiles, Physique, Instrumentation (GEPI), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Lunar and Planetary Laboratory [Tucson] (LPL), and University of Arizona

Subjects
010504 meteorology & atmospheric sciences, Astrophysics::Cosmology and Extragalactic Astrophysics, 01 natural sciences, 7. Clean energy, Heliosphere, Basic research, 0103 physical sciences, Heliopause, 010303 astronomy & astrophysics, 0105 earth and related environmental sciences, [PHYS]Physics [physics], Physics, [SDU.ASTR.SR]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Solar and Stellar Astrophysics [astro-ph.SR], Foundation (engineering), Interstellar hydrogen, Astronomy, Geophysics, Radiation transfer, Unknown Source, Astrophysics - Solar and Stellar Astrophysics, 13. Climate action, Space and Planetary Science, Backscattered lyman alpha, Physics::Space Physics, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], Astrophysics - Earth and Planetary Astrophysics
Abstract

In this work, we present for the first time the Lyman $\alpha$ intensities measured by Voyager 1/UVS in 2003-2014 (at 90-130 AU from the Sun). During this period Voyager 1 measured the Lyman $\alpha$ emission in the outer heliosphere at an almost fixed direction close to the upwind (that is towards the interstellar flow). The data show an unexpected behavior in 2003-2009: the ratio of observed intensity to the solar Lyman $\alpha$ flux is almost constant. Numerical modelling of these data is performed in the frame of a state-of-art self-consistent kinetic-MHD model of the heliospheric interface (Izmodenov & Alexashov, 2015). The model results, for various interstellar parameters, predict a monotonic decrease of intensity not seen in the data. We propose two possible scenarios that explain the data qualitatively. The first is the formation of a dense layer of hydrogen atoms near the heliopause. Such a layer would provide an additional backscattered Doppler shifted Lyman $\alpha$ emission, which is not absorbed inside the heliosphere and may be observed by Voyager. About 35 R of intensity from the layer is needed. The second scenario is an external non-heliospheric Lyman $\alpha$ component, which could be galactic or extragalactic. Our parametric study shows that $\sim$25 R of additional emission leads to a good qualitative agreement between the Voyager 1 data and the model results., Comment: accepted in Journal of Geophysical Research: Space Physics

Published
2017

204. Photochemical Escape of Oxygen from Mars: Consequences for Climate History

Author

Lillis, R., Deighan, Justin, Fox, J. L., Bougher, S., Lee, Y., Combi, M., Leblanc, François, Cravens, T., Rahmati, A., Gröller, H., Jakosky, B., Space Sciences Laboratory [Berkeley] (SSL), University of California [Berkeley], University of California-University of California, Laboratory for Atmospheric and Space Physics [Boulder] (LASP), University of Colorado [Boulder], Department of Physics [Dayton], Wright State University, Department of Atmospheric, Oceanic, and Space Sciences [Ann Arbor] (AOSS), University of Michigan [Ann Arbor], University of Michigan System-University of Michigan System, HELIOS - LATMOS, Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Department of Physics and Astronomy [Lawrence Kansas], University of Kansas [Lawrence] (KU), Lunar and Planetary Laboratory [Tucson] (LPL), University of Arizona, University of California [Berkeley] (UC Berkeley), and University of California (UC)-University of California (UC)

Subjects
[SDU]Sciences of the Universe [physics], Physics::Space Physics, Astrophysics::Solar and Stellar Astrophysics, Astrophysics::Earth and Planetary Astrophysics
Abstract

International audience; As well as this effort using in situ data, MAVEN can also constrain photochemical escape using remote sensing of the oxygen corona with the Imaging Ultraviolet Spectrograph (IUVS) [12, 13], the Solar Energetic Particle (SEP) instrument and the Solar Wind Ion Analyzer [14]. These multiple methods will eventually allow validation of photochemical escape from Mars and its dependence on solar and planetary conditions, enabling confident extrapolation back into the past

Published
2017

205. Atmospheric Bulges on Tidally-Locked Satellites

Author

Oza, Apurva, Johnson, Robert E., Leblanc, François, HELIOS - LATMOS, Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Department of Materials Science and Engineering [Charlottesville] (MS), University of Virginia [Charlottesville], University of Virginia, and Cardon, Catherine

Subjects
[SDU] Sciences of the Universe [physics], [SDU]Sciences of the Universe [physics], Physics::Space Physics, Astrophysics::Earth and Planetary Astrophysics
Abstract

International audience; We use a simple analytic model to examine the spatial distribution of a volatile species in a surface-bounded atmosphere on a rotating object that is tidally-locked to its parent body. Spatial asymmetries in such atmospheres have recently been observed via ultraviolet auroral emissions from the exospheres of the icy satellites Europa and Ganymede. The Hubble Space Telescope observations indicate that these satellites host unique, surface-bounded O2 exospheres which bulge towards dusk. Using a simple 1-D mass conservation balance we examine the nature of the volatile source, the surface temperature profile, the spatial morphology of the loss process, and the adsorption and desorption properties of the surfaces to understand the spatial distribution of the surface-bounded atmosphere for a number of objects. Since the ballistic hop distances are much smaller than the satellite radii, we show that the observed asymmetries at Europa and Ganymede can be simply due to a strongly thermally-dependent source, although asymmetries in the plasma-induced loss could contribute. A key condition for these atmospheric bulges that are shifted towards dusk is the relationship between the rotation rate and the atmospheric loss rate.

Published
2017

206. Détection et de la dynamique des exosphères satellitaires

Author

Oza, Apurva, HELIOS - LATMOS, Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Université Pierre et Marie Curie - Paris VI, Jean-Jacques Berthelier, and François Leblanc

Subjects
Glaces, Atmospheres, Atmosphères, [SDU.STU.PL]Sciences of the Universe [physics]/Earth Sciences/Planetology, Satellites, Moons, Dioxygène, Nanotechnologie, Europa, Exosphere
Abstract

I present a multidisciplinary analysis on the behavior of asurface-bounded exosphere synchronously rotating about its primary. Anexosphere is the boundless, external envelope of gas extending from aplanetary surface or atmosphere. This collisionless gas represents theinterface between planets and stars, as it directly interacts with theinterplanetary medium. Should the exosphere possess a population ofvolatiles strongly coupled with the surface temperature, the exospherewill be capable of experiencing a diurnal cycle over an orbitalperiod. I provide the first evidence of the existence of such adiurnal cycle in the molecular oxygen exospheres of two of Jupiter’sicy moons: Europa and Ganymede. The evidence was surmounted by anin-depth comparison between the near-surface ultraviolet oxygenaurorae observations by the Hubble Space Telescope and 3-D Monte Carlosimulations of Europa’s near-surface O2 exosphere, where both auroraeand exospheres where found to be strongly peaking at dusk. Thedusk-over-dawn asymmetry analysis also provides evidence that Europamay harbor a large O2 reservoir embedded in its ice today. Inaddition to O2 , I present the first orbital simulations of all knownwater-products at Europa, and provide perspectives on discerning theeffects of cryovolcanism on the exosphere. Lastly, at LATMOS, Icharacterized a novel ionization source: a carbon nanotube electrongun (CNTeg). This in-situ device used for neutral mass spectrometry,may prove to be a very efficient electron emitter (P < 10 milliWatts)and should aid future searches to detect trace gases in any exosphere.; Je présente une analyse multidisciplinaire du comportement d’une exosphère d’un satellite dont la limite inférieure est une surface solide. Une exosphère par définition n’a pas de limite supérieure, est constituée d’un gaz dont la dynamique n’est pas régie par des collisions et correspond à la région d’interaction entre un objet planétaire et sa planète mère ou étoile. Dans cette thèse, je montrerai qu’une population exosphérique d’un satellite qui serait volatile et dont la dynamique serait fortement dépendante de la température de surface, aura une évolution orbitale synchrone avec le cycle diurne. Par exemple, l’oxygène moléculaire autour d’Europa et de Ganymède, satellites de Jupiter,devrait suivre une telle évolution. Je m’attacherai donc à comparer les résultats d’un modèle 3D Monte Carlo reconstruisant l’évolution de cette exosphère et les observations d’émissions aurorales par le télescope Hubble pour souligner la persistance d’une asymétrie matin/soir caractéristique de ce cycle diurne. Par ailleurs,une analyse plus théorique de l’origine de cette asymétrie nous suggère qu’un réservoird’O2 sous forme gazeuse dans le régolite pourrait être à l’origine de la formation de cette exosphère. En plus de la description de l’O2 exosphérique autour d’Europa, je soulignerai les différences notables avec l’H2O et ses produits. Enfin, j’ai également travaillé à la caractérisation d’une nouvelle technologie pour une source d’ionisation basée sur l’utilisation de nano-tubes de carbone. Cet émetteur d’électron utilisé pour la spectrométrie de masse neutre s’avère nettement plus efficace que les émetteurs classiquement utilisés dans le spatial et devrait donc nous aider à explorer ces exosphères.

Published
2017

207. Effect of the lateral exospheric transport on the horizontal hydrogen distribution at the exobase of Mars

Author

Chaufray, Jean-Yves, Yelle, Roger, González-Galindo, F., Forget, François, Lopez-Valverde, Miguel, Leblanc, François, Modolo, Ronan, HELIOS - LATMOS, Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), University of Arizona, Laboratoire de Météorologie Dynamique (UMR 8539) (LMD), Département des Géosciences - ENS Paris, École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-École des Ponts ParisTech (ENPC)-École polytechnique (X)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC), Instituto de Astrofísica de Andalucía (IAA), Consejo Superior de Investigaciones Científicas [Madrid] (CSIC), Cardon, Catherine, Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-École des Ponts ParisTech (ENPC)-Centre National de la Recherche Scientifique (CNRS)-Département des Géosciences - ENS Paris, École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-École normale supérieure - Paris (ENS-PSL), and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)

Subjects
[SDU.ASTR]Sciences of the Universe [physics]/Astrophysics [astro-ph], [SDU.ASTR] Sciences of the Universe [physics]/Astrophysics [astro-ph]
Abstract

International audience; We describe the horizontal distribution of hydrogen density at the exobase of Mars as simulated by coupling a 3D GCM with an exospheric balistic model, taking into account the flight balistic time of the exopheric hydrogen atoms. Such a description is more realistic than the assumptions used in our past study [4]. We simulate 4 Martian rotations at three different seasons. The horizontal variations of the hydrogen density at the exobase are reduced when the exospheric balistic transport is included compared to our previous simulations.

Published
2017

208. On Mars' atmospheric sputtering after MAVEN first two years

Author

Leblanc, François, Modolo, Ronan, Curry, Shannon M., Luhmann, Janet, Lillis, Robert, Chaufray, Jean-Yves, Hara, Takuya, Mcfadden, James P., Halekas, Jasper S., Eparvier, Frank, Larsen, D., Connerney, J., Jakosky, Bruce, PLANETO - LATMOS, Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), HELIOS - LATMOS, Space Sciences Laboratory [Berkeley] (SSL), University of California [Berkeley], University of California-University of California, Laboratory for Atmospheric and Space Physics [Boulder] (LASP), University of Colorado [Boulder], NASA Goddard Space Flight Center (GSFC), University of California [Berkeley] (UC Berkeley), and University of California (UC)-University of California (UC)

Subjects
[SDU.ASTR.SR]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Solar and Stellar Astrophysics [astro-ph.SR], Physics::Space Physics, [SDU.ASTR.EP]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Earth and Planetary Astrophysics [astro-ph.EP], Astrophysics::Solar and Stellar Astrophysics, Astrophysics::Earth and Planetary Astrophysics, Physics::Atmospheric and Oceanic Physics, Physics::Geophysics
Abstract

International audience; Mars may have lost a significant part of its atmosphere into space along its history, in particular since the end of its internal dynamo, 4.1 Gyr ago. The sputtering of the atmosphere by precipitating planetary picked up ions accelerated by the solar wind is one of the processes that could have significantly contributed to this atmospheric escape. We here present a two years base analysis of MAVEN observation of the precipitating flux, in particular the dependency of the precipitating intensity with solar zenith angle and used this measurement to model the expected escape rate and exosphere induced by this precipitation.

Published
2017

209. Planetary data distribution by the French Plasma Physics Data Centre (CDPP): the example of Rosetta Plasma Consortium in the perspective of Solar Orbiter, Bepi-Colombo and JUICE

Author

Génot, V., Dufourg, N., Bouchemit, M., Budnik, E., André, N., Cecconi, B., Gangloff, M., Durand, J., Pitout, F., Jacquey, C., Rouillard, A., Jourdane, N., Heulet, D., Lavraud, B., Ronan Modolo, Garnier, P., Louarn, P., Pierre Henri, Galand, M., Beth, A., Institut de recherche en astrophysique et planétologie (IRAP), Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS), Centre National d’Études Spatiales [Paris] (CNES), NOVELTIS [Sté], Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA (UMR_8109)), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), HELIOS - LATMOS, Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de Physique et Chimie de l'Environnement et de l'Espace (LPC2E), Observatoire des Sciences de l'Univers en région Centre (OSUC), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Centre National d’Études Spatiales [Paris] (CNES), Department of Physics [Imperial College London], and Imperial College London

Subjects
Plasma sensors, instrument consortia, [SDU]Sciences of the Universe [physics], BepiColombo, Rosetta mission, CDPP, Solar orbiter, French Plasma Physics Data Centre, JUICE
Abstract

International audience; The French Plasma Physics Data Centre (CDPP, http://www.cdpp.eu/ ) has been addressing for almost the past 20 years all issues pertaining to natural plasma data distribution and valorization. Initially established by CNES and CNRS on the ground of a solid data archive, CDPP activities diversified with the advent of broader networks and interoperability standards, and through fruitful collaborations (e.g. with NASA/PDS). Providing access to remote data, designing and building science driven analysis tools then became at the forefront of CDPP developments. In the frame of data distribution, the CDPP has provided to the Rosetta Plasma Consortium (RPC), a suite of five different plasma sensors, with the possibility to visualize plasma data acquired by the Rosetta mission through its data analysis tool AMDA. AMDA was used during the operational phase of the Rosetta mission, facilitating data access between different Rosetta PI sensor teams, thus allowing 1/ a more efficient instruments operation planning and 2/ a better understanding of single instrument observations in the context of other sensor measurements and of more global observations. The data are now getting open to the public via the AMDA tool as they are released to the ESA/PSA. These in-situ data are complemented by model data, for instance, a solar wind propagation model (see http://heliopropa.irap.omp.eu ) or illumination maps of 67P (available through http://vespa.obspm.fr ). The CDPP also proposes 3D visualization tool for planetary / heliospheric environments which helps putting data in context (http://3dview.cdpp.eu ); for instance all comets and asteroids in a given volume and for a given time interval can be searched and displayed. From this fruitful experience the CDPP intends to play a similar role for the forthcoming data of the Solar Orbiter, Bepi-Colombo and JUICE missions as it is officially part of several instrument consortia. Beside highlighting the current database and products, the presentation will show how these future data could be presented and valorized through a combined use of the tools and models provided by the CDPP.

Published
2017

210. Pressure balance boundaries in the dayside magnetosphere of Mars

Author

Holmberg, M., Andre, N., Modolo, Ronan, Andersson, L., Mazelle, Christian, Garnier, P., Steckiewicz, M, Halekas, J., Institut de recherche en astrophysique et planétologie (IRAP), Institut national des sciences de l'Univers (INSU - CNRS)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Observatoire Midi-Pyrénées (OMP), Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS), HELIOS - LATMOS, Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Laboratory for Atmospheric and Space Physics [Boulder] (LASP), University of Colorado [Boulder], Department of Physics and Astronomy [Iowa City], University of Iowa [Iowa City], Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), and Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS)

Subjects
[SDU]Sciences of the Universe [physics], Physics::Space Physics, Astrophysics::Earth and Planetary Astrophysics
Abstract

International audience; We use data from the MAVEN and MEX spacecraft to study pressure balance boundaries in the Martian dayside magnetosphere. We use 15 orbit segments from year 2015 when MAVEN and MEX simultaneously were within SZA

Published
2017

211. Comet Siding Spring's influence on the Mars' ionosphere

Author

Witasse, Olivier, Sánchez-Cano, B., Molina-Cuberos, Gregorio, Blelly, Pierre-Louis, Lester, M., Leblanc, François, Modolo, Ronan, Chaufray, Jean-Yves, Gronoff, Guillaume, Espley, Jared, Costa, M., Giuranna, M., European Space Research and Technology Centre (ESTEC), European Space Agency (ESA), Department of Physics and Astronomy [Leicester], University of Leicester, Department of Electromagnetism and Electronics [Murcia], Universidad de Murcia, Institut de recherche en astrophysique et planétologie (IRAP), Institut national des sciences de l'Univers (INSU - CNRS)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Observatoire Midi-Pyrénées (OMP), Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS), HELIOS - LATMOS, Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), NASA Langley Research Center [Hampton] (LaRC), GSFC Planetary Magnetospheres Laboratory, NASA Goddard Space Flight Center (GSFC), Istituto Nazionale di Astrofisica (INAF), Agence Spatiale Européenne = European Space Agency (ESA), Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), and Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS)

Subjects
[SDU]Sciences of the Universe [physics]
Abstract

International audience; On October 19th 2014, Mars experienced a close encounter with Comet C/2013 A1 (Siding Spring), at a distance of ~138,000 km. The coma washed over Mars and the planet passed directly through the cometary debris stream, producing significant effects in Mars' upper atmosphere. We present here an overview of ionospheric measurements performed during the comet encounter with Mars Express, MAVEN, and Mars Reconnaissance Orbiter. We discuss the comet's influence on the ionosphere through different processes that work at different altitudes: magnetospheric disturbances, impact of cometary pickup ions, and deposition of cometary dust.

Published
2017

212. Radio and plasma wave observations during Cassini's Grand Finale

Author

Kurth, W. S., Canu, P., Baptiste Cecconi, Farrell, W. M., Fischer, G., Galopeau, P., Gurnett, D. A., Hospodarsky, G. B., Lamy, L., Lecacheux, A., Louarn, P., Macdowall, R. J., Menietti, J. D., Morooka, M., Pedersen, A., Persoon, A. M., Sulaiman, A., Wahlund, J. -E, Zarka, P., Department of Physics and Astronomy [Iowa City], University of Iowa [Iowa City], Laboratoire de Physique des Plasmas (LPP), Université Paris-Sud - Paris 11 (UP11)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-École polytechnique (X)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), NASA Goddard Institute for Space Studies (GISS), NASA Goddard Space Flight Center (GSFC), Space Research Institute of Austrian Academy of Sciences (IWF), Austrian Academy of Sciences (OeAW), HELIOS - LATMOS, Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Institut de recherche en astrophysique et planétologie (IRAP), Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS), Swedish Institute of Space Physics [Uppsala] (IRF), University of Oslo (UiO), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-École polytechnique (X)-Sorbonne Université (SU)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Institut national des sciences de l'Univers (INSU - CNRS)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Observatoire Midi-Pyrénées (OMP), and Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS)

Subjects
[SDU]Sciences of the Universe [physics], Physics::Space Physics, Astrophysics::Earth and Planetary Astrophysics
Abstract

International audience; Cassini has commenced its high inclination Grand Finale orbits with perikrones falling between the inner edge of the D ring and the upper limits of Saturn's atmosphere. The Cassini Radio and Plasma Wave Science (RPWS) instrument makes a variety of observations in these unique orbits including Saturn kilometric radiation, plasma waves such as auroral hiss associated with Saturn's auroras, dust via impacts with Cassini, and the upper reaches of Saturn's ionosphere. This paper will provide an overview of the RPWS results from this new and final phase of the Cassini mission with the unique opportunities afforded by the orbit.

Published
2017

213. Test particle simulation of Ganymede’s plasma environment

Author

Carnielli, G., Galand, M., Leblanc, François, Leclercq, Ludivine, Modolo, Ronan, Beth, A., Department of Physics [Imperial College London], Imperial College London, Space and Atmospheric Physics Group [London], Blackett Laboratory, Imperial College London-Imperial College London, HELIOS - LATMOS, Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), University of Virginia [Charlottesville], and University of Virginia

Subjects
[SDU]Sciences of the Universe [physics], Physics::Space Physics, Astrophysics::Earth and Planetary Astrophysics, Physics::Geophysics
Abstract

International audience; So far, Ganymede’s nearby plasma environment has been in part characterized only during a few flybys of the moon by the Galileo spacecraft at the end of the 1990s and through a few remote observations of auroral emissions by the Hubble Space Telescope. Our knowledge of the plasma composition, density and dynamics in Ganymede’s magnetosphere remains therefore limited. The JUICE spacecraft will characterize in detail the exosphere, ionosphere and particle environment around the moon. Prior to arrival, models have been developed to predict these regions and their interaction with the background Jovian particles and magnetic field.We have developed the first 3D test particle model of Ganymede’s ionosphere. The model is driven by: (1) the number densities of neutral species from the exospheric model of Leblanc et al. (Icarus, 2017), (2) solar extreme ultraviolet radiation (Woods et al. 2005), (3) electron fluxes coming from the Jovian plasma around the moon (Mauk et al., 2004) and (4) the electromagnetic field from the hybrid model of Leclercq et al. (PSS, in revision). In the simulation, the ionospheric ions are produced via photoionization and electron- impact ionization of the neutral exosphere. The test particles move under the influence of the magnetic and electric fields derived from the hybrid model.We will present the first three-dimensional maps of number densities and bulk speeds of the main ion species produced in Ganymede’s ionosphere. We will show and interpret our derived ion-impact 2D maps at the surface for both ionospheric ions and Jovian ions (coming from the Jovian plasma sheet), and provide sputtering rates of neutral molecule production resulting from these impacts. We will also quantify the importance of the charge-exchange process between the ions and exospheric species in terms of production of energetic neutrals, which is relevant for exospheric models. Finally, we will assess the variability of the ionosphere over a revolution of Ganymede around Jupiter, driven by the change in the neutral exosphere (Leblanc et al., 2017) and in the angle Sun-moon direction. We will evaluate its potential implications on the variability of Ganymede’s magnetic environment.

Published
2017

214. SPICAM observations of thermospheric airglow during the 2007 dust storm

Author

Schneider, N., Chaffin, M., Everding, D., Leblanc, François, Chaufray, Jean-Yves, Montmessin, Franck, Bertaux, Jean-Loup, Laboratory for Atmospheric and Space Physics [Boulder] (LASP), University of Colorado [Boulder], HELIOS - LATMOS, Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), PLANETO - LATMOS, and Cardon, Catherine

Subjects
[SDU] Sciences of the Universe [physics], [PHYS.PHYS.PHYS-AO-PH]Physics [physics]/Physics [physics]/Atmospheric and Oceanic Physics [physics.ao-ph], [SDU]Sciences of the Universe [physics], [PHYS.PHYS.PHYS-AO-PH] Physics [physics]/Physics [physics]/Atmospheric and Oceanic Physics [physics.ao-ph]
Abstract

International audience; In 2007 (Mars Year 28), Mars experienced a global dust storm. Previous studies have reported large changes in the H Lyman alpha coronal airglow during this period, corresponding to a large decrease in H escape fluxes during the declining phase of the dust storm. Here we present airglow measurements of CO Cameron band and CO+2 UV Doublet emission in the thermosphere from 2007 data gathered by the SPI-CAM (SPectroscopy for the Investigation of the Characteristics of the Atmosphere of Mars) instrument on Mars Express. During the dust storm period in late 2007, lower atmospheric temperatures were enhanced, pushing the thermosphere to higher altitudes. At the same time, more intense UV heating resulting from the perihelion passage of Mars resulted in extended upper atmospheric scale heights. We compare our retrievals and techniques to previous studies, which found no enhancement in thermospheric scale heights during this period.

Published
2017

215. Segmentation of photospheric magnetic elements corresponding to coronal features to understand the EUV and UV irradiance variability

Author

Véronique Delouille, Luc Damé, S. T. Kumara, Joe Zender, Gabriel Giono, Jean-François Hochedez, Matthias Bergmann, Rangaiah Kariyappa, European Space Research and Technology Centre (ESTEC), European Space Agency (ESA), Vemana Institute of Technology, Department of Space and Plasma Physics [Stockholm], KTH School of Electrical Engineering, Royal Institute of Technology [Stockholm] (KTH )-Royal Institute of Technology [Stockholm] (KTH ), Julius-Maximilians-Universität Würzburg [Wurtzbourg, Allemagne] (JMU), Royal Observatory of Belgium [Brussels] (ROB), HELIOS - LATMOS, Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), APS College of Engineering, Agence Spatiale Européenne = European Space Agency (ESA), and Julius-Maximilians-Universität Würzburg (JMU)

Subjects
010504 meteorology & atmospheric sciences, Irradiance, Coronal hole, Astrophysics, Solar irradiance, 01 natural sciences, Coronal radiative losses, 0103 physical sciences, Astrophysics::Solar and Stellar Astrophysics, 010303 astronomy & astrophysics, 0105 earth and related environmental sciences, Physics, Radiometer, [SDU.ASTR.SR]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Solar and Stellar Astrophysics [astro-ph.SR], Sun, Astronomy, Astronomy and Astrophysics, Corona, Nanoflares, 13. Climate action, Space and Planetary Science, Extreme ultraviolet, Magnetic fields, Physics::Space Physics, Astrophysics::Earth and Planetary Astrophysics
Abstract

Context. The magnetic field plays a dominant role in the solar irradiance variability. Determining the contribution of various magnetic features to this variability is important in the context of heliospheric studies and Sun-Earth connection. Aims. We studied the solar irradiance variability and its association with the underlying magnetic field for a period of five years (January 2011–January 2016). We used observations from the Large Yield Radiometer (LYRA), the Sun Watcher with Active Pixel System detector and Image Processing (SWAP) on board PROBA2, the Atmospheric Imaging Assembly (AIA), and the Helioseismic and Magnetic Imager (HMI) on board the Solar Dynamics Observatory (SDO). Methods. The Spatial Possibilistic Clustering Algorithm (SPoCA) is applied to the extreme ultraviolet (EUV) observations obtained from the AIA to segregate coronal features by creating segmentation maps of active regions (ARs), coronal holes (CHs) and the quiet sun (QS). Further, these maps are applied to the full-disk SWAP intensity images and the full-disk (FD) HMI line-of-sight (LOS) magnetograms to isolate the SWAP coronal features and photospheric magnetic counterparts, respectively. We then computed full-disk and feature-wise averages of EUV intensity and line of sight (LOS) magnetic flux density over ARs/CHs/QS/FD. The variability in these quantities is compared with that of LYRA irradiance values. Results. Variations in the quantities resulting from the segmentation, namely the integrated intensity and the total magnetic flux density of ARs/CHs/QS/FD regions, are compared with the LYRA irradiance variations. We find that the EUV intensity over ARs/CHs/QS/FD is well correlated with the underlying magnetic field. In addition, variations in the full-disk integrated intensity and magnetic flux density values are correlated with the LYRA irradiance variations. Conclusions. Using the segmented coronal features observed in the EUV wavelengths as proxies to isolate the underlying magnetic structures is demonstrated in this study. Sophisticated feature identification and segmentation tools are important in providing more insights into the role of various magnetic features in both the short- and long-term changes in the solar irradiance.

Published
2017

216. Energetic particle showers over Mars from comet Siding-Spring

Author

Sánchez-Cano, B., Witasse, Olivier, Lester, M., Rahmati, A., Cowley, S.W.H., Ambrosi, R., Costa, M., Espley, J., Guo, J., Leblanc, François, Lillis, R., Plaut, J.J., Wimmer-Schweingruber, R.F., Department of Physics and Astronomy [Leicester], University of Leicester, European Space Research and Technology Centre (ESTEC), European Space Agency (ESA), Space Sciences Laboratory [Berkeley] (SSL), University of California [Berkeley], University of California-University of California, European Space Astronomy Centre (ESAC), GSFC Planetary Magnetospheres Laboratory, NASA Goddard Space Flight Center (GSFC), Institut für Experimentelle und Angewandte Physik [Kiel] (IEAP), Christian-Albrechts-Universität zu Kiel (CAU), HELIOS - LATMOS, Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Jet Propulsion Laboratory (JPL), NASA-California Institute of Technology (CALTECH), Agence Spatiale Européenne = European Space Agency (ESA), University of California [Berkeley] (UC Berkeley), and University of California (UC)-University of California (UC)

Subjects
[SDU]Sciences of the Universe [physics]
Abstract

International audience; On October 19th 2014, Mars experienced a close encounter with Comet C/2013 A1 (Siding Spring), at a distance of only 141,000 km, or one third the Earth Moon distance. The gaseous coma washed over Mars and Mars passed directly through the cometary debris stream [1]. As a close encounter of this type is predicted only once in 100,000 years, this is likely the only opportunity for measurements associated with planetary/cometary encounters. Additionally, the encounter was masked by the transit of a powerful Coronal Mass Ejection (CME) 44 hours before [2]. Thus, the comet flyby took place when the Martian plasma system was still recovering from the CME impact, whilst the solar wind passing Mars remained significantly disturbed. In this study, we investigate the interaction of the comet with the solar wind, and their effects on the shock-accelerated energetic particles that precipitate into the Mars’ atmosphere. The study is based on data from MAVEN, Mars Odyssey, MSL and Mars Express missions.

Published
2017

217. Solar Wind Interaction and Atmospheric Escape

Author

David Brain, Bruce M. Jakosky, Ronan Modolo, Sergey Barabash, Firat Durut, Stephen W. Bougher, Laboratory for Atmospheric and Space Physics [Boulder] (LASP), University of Colorado [Boulder], Swedish Institute of Space Physics [Uppsala] (IRF), Department of Climate and Space Sciences and Engineering (CLaSP), University of Michigan [Ann Arbor], University of Michigan System-University of Michigan System, Department of Physics and Astronomy [Iowa City], University of Iowa [Iowa City], HELIOS - LATMOS, Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Robert M. Haberle, R. Todd Clancy, François Forget, Michael D. Smith, Richard W. Zurek (eds.), Cardon, Catherine, and Robert M. Haberle, R. Todd Clancy, François Forget, Michael D. Smith, Richard W. Zurek (eds.)

Subjects
010504 meteorology & atmospheric sciences, Atmospheric escape, [SDU.ASTR.SR]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Solar and Stellar Astrophysics [astro-ph.SR], [SDU.ASTR.EP]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Earth and Planetary Astrophysics [astro-ph.EP], [SDU.ASTR.EP] Sciences of the Universe [physics]/Astrophysics [astro-ph]/Earth and Planetary Astrophysics [astro-ph.EP], Atmospheric sciences, 01 natural sciences, Solar wind, Polar wind, 0103 physical sciences, [SDU.ASTR.SR] Sciences of the Universe [physics]/Astrophysics [astro-ph]/Solar and Stellar Astrophysics [astro-ph.SR], Environmental science, 010303 astronomy & astrophysics, ComputingMilieux_MISCELLANEOUS, 0105 earth and related environmental sciences
Abstract

International audience

Published
2017

218. Design of an optical sun sensor for a space application: a reliable passive sun tracking device for the SOLAR/SOLSPEC instrument

Author

Abdanour Irbah, Mustapha Meftah, Dominique Sluse, David Bolsée, Luc Damé, Nuno Pereira, A. Michel, Belgian Institute for Space Aeronomy / Institut d'Aéronomie Spatiale de Belgique (BIRA-IASB), The Belgian User Support and Operations Centre (B.USOC), STRATO - LATMOS, Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), HELIOS - LATMOS, Francesco Baldini, Jiri Homola, and Robert A. Lieberman

Subjects
Physics, 010504 meteorology & atmospheric sciences, Irradiance, Position sensitive device, Orbital mechanics, Computer Science::Numerical Analysis, 01 natural sciences, 7. Clean energy, [SDU.ASTR.IM]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Instrumentation and Methods for Astrophysic [astro-ph.IM], Sun sensor, Spectroradiometer, Physics::Space Physics, 0103 physical sciences, International Space Station, Astrophysics::Solar and Stellar Astrophysics, Astrophysics::Earth and Planetary Astrophysics, 010303 astronomy & astrophysics, Zenith, 0105 earth and related environmental sciences, Space environment, Remote sensing
Abstract

International audience; SOLAR/SOLSPEC, a spectroradiometer measuring solar spectral irradiance is an instruments of the SOLAR payload mounted on the zenith external platform of the European Columbus module of the International Space Station. Solar flux is received by the SOLAR instruments thanks to the Coarse Pointing Device (CPD). A complementary Sun position tracking module, the Position Sensitive Device (PSD), is integrated in SOLAR/SOLSPEC. The PSD module has been a useful tool to monitor for misalignments between the CPD and the SOLAR payload. It is used in SOLAR/SOLSPEC's operations to follow the quality of the Sun tracking. The PSD module is also valuable to monitor for SOLAR/SOLSPEC's three spectrometers (ultraviolet, visible, infrared) angular response in orbit. We first give a detailed description of the PSD's functionalities. We then present the results of the PSD data analysis. We will show that the PSD module has, despite working in a severe space environment, preserved its full potential from 2008 up to 2017 thanks to its design and appropriate selection of components. We conclude that its robustness makes of the PSD module a simple, yet reliable, instrument useful for future long term space-based missions.

Published
2017

219. Statistical analysis of solar events associated with SSC over one year of solar maximum during cycle 23: propagation and effects from the Sun to the Earth

Author

Cornilleau-Wehrlin, Nicole, Bocchialini, Karine, Menvielle, Michel, Chambodut, Aude, Fontaine, Dominique, Grison, Benjamin, Marchaudon, Aurélie, Pick, Monique, Pitout, Frédéric, Schmieder, Brigitte, Régnier, Stéphane, Ioannis Zouganelis, Laboratoire de Physique des Plasmas (LPP), Université Paris-Sud - Paris 11 (UP11)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-École polytechnique (X)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Institut d'astrophysique spatiale (IAS), Université Paris-Sud - Paris 11 (UP11)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Centre National d’Études Spatiales [Paris] (CNES), HELIOS - LATMOS, Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Institut de physique du globe de Strasbourg (IPGS), Université de Strasbourg (UNISTRA)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Institute of Atmospheric Physics [Prague] (IAP), Czech Academy of Sciences [Prague] (CAS), Institut de recherche en astrophysique et planétologie (IRAP), Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS), Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Institut des Systèmes Intelligents et de Robotique (ISIR), Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS), Department of Mathematics, Physics and Electrical Engineering [Newcastle], University of Northumbria at Newcastle [United Kingdom], European Space Astronomy Centre (ESAC), Agence Spatiale Européenne = European Space Agency (ESA), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-École polytechnique (X)-Sorbonne Université (SU)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Université Paris-Sud - Paris 11 (UP11)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Université de Strasbourg (UNISTRA)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS), Institut national des sciences de l'Univers (INSU - CNRS)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Observatoire Midi-Pyrénées (OMP), Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS), and European Space Agency (ESA)

Subjects
[SDU.ASTR.SR]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Solar and Stellar Astrophysics [astro-ph.SR], Physics::Space Physics, Astrophysics::Solar and Stellar Astrophysics, Astrophysics::Earth and Planetary Astrophysics
Abstract

International audience; Taking the 32 sudden storm commencements (SSC) listed by the observatory de l'Ebre / ISGI over the year 2002 (maximal solar activity) as a starting point, we performed a statistical analysis of the related solar sources, solar wind signatures, and terrestrial responses. For each event, we characterized and identified, as far as possible, (i) the sources on the Sun (Coronal Mass Ejections -CME-), with the help of a series of criteria (velocities, drag coefficient, radio waves, helicity), as well as (ii) the structure and properties in the interplanetary medium, at L1, of the event associated to the SSC: magnetic clouds -MC-, non-MC interplanetary coronal mass ejections -ICME-, co-rotating/stream interaction regions -SIR/CIR-, shocks only and unclear events that we call "miscellaneous" events. The observed Sun-to-Earth travel times are compared to those estimated using existing simple models of propagation in the interplanetary medium. This comparison is used to statistically assess performances of various models. The geoeffectiveness of the events, classified by category at L1, is analysed by their signatures in the Earth ionized (magnetosphere and ionosphere) and neutral (thermosphere) environments, using a broad set of in situ, remote and ground based instrumentation. The role of the presence of a unique or of a multiple source at the Sun, of its nature, halo or non halo CME, is also discussed. The set of observations is statistically analyzed so as to evaluate and compare the geoeffectiveness of the events. The results obtained for this set of geomagnetic storms started by SSCs is compared to the overall statistics of year 2002, relying on already published catalogues of events, allowing assessing the relevance of our approach (for instance the all 12 well identified Magnetic Clouds of 2002 give rise to SSCs).

Published
2017

220. Analysis of Saturnian planetary rotation following the knowledge on Jovian radio emission

Author

Boudjada, Mohammed Y., Galopeau, Patrick H. M., Sawas, Sami, Lammer, Helmut, Institut für Weltraumforschung [Graz] (IWF), Osterreichische Akademie der Wissenschaften (ÖAW), HELIOS - LATMOS, Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Institute of communications and wave propagation [Graz], Graz University of Technology [Graz] (TU Graz), Cardon, Catherine, and Institut für Weltraumforschung = Space Research institute [Graz] (IWF)

Subjects
[SDU] Sciences of the Universe [physics], [SDU]Sciences of the Universe [physics], Physics::Space Physics, Astrophysics::Earth and Planetary Astrophysics
Abstract

International audience; We report on the Saturnian Radio Emission (SRE) recorded at Saturn by the Cassini Radio and Plasma Wave Science experiment (RPWS). We attempt to estimate the planetary rotation by applying the spectral method previously considered for the Jupiter radio emissions. This technique consists to distinguish between the spectral patterns occurring during one full Jovian rotation. Hence symmetrical features act around the axis of the planetary magnetic field due to the hollow cone beam. Therefore arc shapes appear with different orientations, i.e. vertex-early and -late arcs. This spectral 'symmetry' is fortified by the inclination between the geographical and the magnetic axes. The Saturnian radio emissions exhibit more spectral complexity because both axes (.i.e. magnetic and geographic) are quasi-aligned. Arc shapes are not frequently observed as in the case of Jupiter. We illustrate in our analysis that there is possibility to separate between Saturnian planetary rotations. Their occurrences are compared to the classic technique based on the variation of the Saturnian Kilometric Radiation (SKR) versus the sub-solar phase and the observation time (Kurth et al., JGR, 113, 2008). We discuss and we show that in several cases the planetary rotation accuracy is less than few minutes when combining both methods. We emphasize on spectral features by showing that the SRE and the SKR exhibit similar planetary rotation despite a difference in the emission frequency range.

Published
2017

221. Numerical simulation of Ganymede's ionosphere

Author

Carnielli, Gianluca, Galand, Marina, Leblanc, François, Leclercq, Ludivine, Modolo, Ronan, Department of Physics [Imperial College London], Imperial College London, HELIOS - LATMOS, Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), University of Virginia [Charlottesville], and University of Virginia

Subjects
[SDU]Sciences of the Universe [physics], Physics::Space Physics, Astrophysics::Earth and Planetary Astrophysics, Physics::Geophysics
Abstract

International audience; Ganymede is one of the four Galilean moons that orbit around Jupiter and the key moon targeted by the JUpiter and ICy moons Explorer (JUICE) mission. Other than being the largest moon in the solar system, it is also the only one known to generate internally a magnetic field which is strong enough to overcome the background jovian field; thus, the moon carves out its own magnetosphere inside that of Jupiter. In addition, at Ganymede's orbit the jovian plasma is sub-Alfvénic and subsonic. The interaction of Ganymede's magnetosphere with its surroundings therefore differs from that of planetary magnetospheres resulting from the interaction with the super-Alfvénic and supersonic solar wind. All this makes Ganymede a peculiar celestial body to study. One of the main goals of the JUICE mission is to characterize Ganymede's exosphere, ionosphere, and magnetosphere as well as its interaction with the jovian surrounding in great details. Ahead of the arrival of JUICE at Jupiter, models have been developed to predict Ganymede's environment. Observational constraints are primarily given from Galileo and from Earth-based telescopes. They remain limited, especially in terms of the ionospheric number density and temperature. To address the currently poorly constrained ionospheric environment, we have developed a test particle model of Ganymede's plasma environment. The model is driven by the densities of neutral species from the exospheric model of Leblanc et al. (Icarus, 2016) and the electromagnetic field taken from the hybrid model of Leclercq et al. (PSS, 2016). The simulation follows the motion of millions of test particles in the environment of the moon and allows to generate maps of ion densities, bulk velocities, and temperatures. We will present simulation outcomes for different ions, including H+, O+, and O2+. We will also discuss how the results from the simulations are relevant to MHD and exospheric models and in interpreting plasma and particle data obtained by Galileo during its close flybys of Ganymede.

Published
2017

222. DR-induced O and C in the thermosphere of the early Mars

Author

Zhao, Jinjin, Chassefière, Eric, Tian, Feng, Chaufray, Jean-Yves, Leblanc, François, Center for Earth System Science [Beijing] (CESS), Tsinghua University [Beijing] (THU), Géosciences Paris Sud (GEOPS), Université Paris-Sud - Paris 11 (UP11)-Centre National de la Recherche Scientifique (CNRS), HELIOS - LATMOS, Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), and Cardon, Catherine

Subjects
[SDU] Sciences of the Universe [physics], [SDU]Sciences of the Universe [physics]
Abstract

International audience; Mars atmospheres changed a lot during its evolution and especially for the early period. Based on previous researches, DR-induced photochemical escape due to dissociative recombination (DR) reactions is an important escape mechanism at early stages. Energetic O and C atoms generated through DR photochemical reactions could overcome collisions with the surrounding background gases then escape. Meantime, surrounding inactive particles could be accelerated by transferred momentum from those hot atoms. Afterwards secondaries formed and could have played an important role in shaping the Martian Coronae especially during its earlier evolution. In order to understand Mars atmospheric stability and evolution, we built a 3-D Monte Carlo Model to simulate atmospheric structures in different period of its history. DR reactions of O2+, CO2+, and CO+ are considered as the sources of energetic O and C. Different thermosphere structures for 1, 3, 10, and 20× present solar XUV conditions, corresponding to solar activity levels 2.5, 3.8, and 4.1 Gyr ago, are considered in this model. The code also simulated contributions of secondary O and C atoms resulting from collisions between DR-induced primary energetic atoms and neutral background species C, O, CO, and CO2. Our previous research, focused on the DR-induced O and C escape from early Mars, reveal that: (1) escape rates of both O and C increase non-monotonically with solar soft X- ray and extreme ultraviolet (XUV) fluxes, because column densities of background species were larger at early times, when the solar XUV flux was larger, deflecting energetic particles through collisions more efficiently. However, due to the same reason the contribution of secondary particles was significantly larger during earlier periods. As high as 30˜40% and 10% secondaries contribute to the total escape of O and C at 20× present solar XUV condition respectively. (2) The time-integrated DR-induced escape of O and C is equivalent to only 1 m global water layer and 20 mbar of CO2 escaping early Mars since 4.5 billion years ago. So the contribution of DR-induced escape to the atmosphere loss is modest during the entire evolution of Mars. That means building a 3-D model to trace the motion and the distribution of those less energetic neutral atoms which trapped in the atmosphere through collision processes, can help us to understand Martian Coronae structure and its interactions with surrounding space environment during different evolution periods.

Published
2017

223. Type III source locations as inferred from stereoscopic observations

Author

Boudjada, Mohammed Y., Lammer, Helmut, Al-Haddad, Eimad, Hammoud, Muhamed, Galopeau, Patrick H. M., Lichtenegger, Herbert, Space Research Institute of Austrian Academy of Sciences (IWF), Austrian Academy of Sciences (OeAW), University of Applied Sciences [Graz], Graz University of Technology [Graz] (TU Graz), HELIOS - LATMOS, Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), and Cardon, Catherine

Subjects
[SDU] Sciences of the Universe [physics], [SDU]Sciences of the Universe [physics], Astrophysics::High Energy Astrophysical Phenomena, Physics::Space Physics
Abstract

International audience; We study the Type III solar bursts simultaneously recorded by radio experiments onboard Cassini, Ulysses and Wind. Those radio bursts cover a large frequency range from about 14 MHz to a few kHz. The corresponding source locations are mainly in the solar corona and the interplanetary medium. The empirical electron density models provide different distances depending on the emission mode, fundamental or harmonic. A real trouble arises due to the distance discrepancies, as inferred from the models. Also the Archimedean spiral trajectories of the electrons, at the origin of the Type III bursts, are another difficulty to correctly estimate the source locations. We show in our analysis that the stereoscopic observations are essential to reduce the source location inaccuracy. We finally discuss the relationship between the Type III beams, the emission modes and the source locations.

Published
2017

224. The structure of the local hot bubble

Author

Massimiliano Galeazzi, Frederick S. Porter, Meng P. Chiao, Dan McCammon, N. E. Thomas, Eugenio Ursino, Michael R. Collier, Kip D. Kuntz, Kelsey M. Morgan, Thomas E. Cravens, Rosine Lallement, Y. Uprety, Steven L. Snowden, Dimitra Koutroumpa, Brian Walsh, Wenhao Liu, Susan T. Lepri, Department of Physics [Coral Gables], University of Miami [Coral Gables], NASA Goddard Space Flight Center (GSFC), Department of Physics and Astronomy [Lawrence Kansas], University of Kansas [Lawrence] (KU), HELIOS - LATMOS, Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Department of Physics and Astronomy [Baltimore], Johns Hopkins University (JHU), Galaxies, Etoiles, Physique, Instrumentation (GEPI), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Department of Atmospheric, Oceanic, and Space Sciences [Ann Arbor] (AOSS), University of Michigan [Ann Arbor], University of Michigan System-University of Michigan System, Department of Physics [Madison], University of Wisconsin-Madison, Department of Physics and Astronomy [Murfreesboro], Middle Tennessee State University [Murfreesboro] (MTSU), Department of Physics [Grinnell], Grinnell College, Department of Mechanical Engineering [Boston], and Boston University [Boston] (BU)

Subjects
010504 meteorology & atmospheric sciences, media_common.quotation_subject, Bubble, Astrophysics::High Energy Astrophysical Phenomena, Thermal ionization, FOS: Physical sciences, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, 01 natural sciences, bubbles, 0103 physical sciences, ROSAT, X-rays, 010303 astronomy & astrophysics, High Energy Astrophysical Phenomena, ISM, 0105 earth and related environmental sciences, media_common, Physics, High Energy Astrophysical Phenomena (astro-ph.HE), [PHYS]Physics [physics], Sounding rocket, [SDU.ASTR.SR]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Solar and Stellar Astrophysics [astro-ph.SR], Astronomy and Astrophysics, Galaxy, Solar wind, Full width at half maximum, 13. Climate action, Space and Planetary Science, Sky, Astrophysics::Earth and Planetary Astrophysics, Astrophysics - High Energy Astrophysical Phenomena, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph]
Abstract

DXL (Diffuse X-rays from the Local Galaxy) is a sounding rocket mission designed to quantify and characterize the contribution of Solar Wind Charge eXchange (SWCX) to the Diffuse X-ray Background and study the properties of the Local Hot Bubble (LHB). Based on the results from the DXL mission, we quantified and removed the contribution of SWCX to the diffuse X-ray background measured by the ROSAT All Sky Survey (RASS). The "cleaned" maps were used to investigate the physical properties of the LHB. Assuming thermal ionization equilibrium, we measured a highly uniform temperature distributed around kT=0.097 keV+/-0.013 keV (FWHM)+/-0.006 keV (systematic). We also generated a thermal emission measure map and used it to characterize the three-dimensional (3D) structure of the LHB which we found to be in good agreement with the structure of the local cavity measured from dust and gas., Comment: 8 pages, 10 figures, Accepted for publication on ApJ

Published
2017

225. A New Solar Spectrum from 656 to 3088 nm

Author

Slimane Bekki, Mustapha Meftah, David Bolsée, Gaël Cessateur, Dominique Sluse, Alain Sarkissian, Alain Hauchecorne, Abdanour Irbah, Nuno Pereira, Luc Damé, Djelloul Djafer, STRATO - LATMOS, Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), HELIOS - LATMOS, Belgian Institute for Space Aeronomy / Institut d'Aéronomie Spatiale de Belgique (BIRA-IASB), Unité de Recherche Appliquée en Energies Renouvelables (URAER), and Ministère de l'Enseignement Supérieur et de la Recherche Scientifique [Algérie] (MESRS)

Subjects
Atmospheric physics, 010504 meteorology & atmospheric sciences, Solar luminosity, Irradiance, Instrumental effects, Solar irradiance, 7. Clean energy, 01 natural sciences, Optics, Observatory, 0103 physical sciences, Astrophysics::Solar and Stellar Astrophysics, Black-body radiation, 010303 astronomy & astrophysics, Instrumentation and data management, 0105 earth and related environmental sciences, Remote sensing, Physics, t International space station, Spectrometer, business.industry, [SDU.ASTR.SR]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Solar and Stellar Astrophysics [astro-ph.SR], Astronomy and Astrophysics, Solar physics, Space and Planetary Science, Physics::Space Physics, Astrophysics::Earth and Planetary Astrophysics, business
Abstract

The solar spectrum is a key parameter for different scientific disciplines such as solar physics, climate research, and atmospheric physics. The SOLar SPECtrometer (SOLSPEC) instrument of the Solar Monitoring Observatory (SOLAR) payload onboard the International Space Station (ISS) has been built to measure the solar spectral irradiance (SSI) from 165 to 3088 nm with high accuracy. To cover the full wavelength range, three double-monochromators with concave gratings are used. We present here a thorough analysis of the data from the third channel/double-monochromator, which covers the spectral range between 656 and 3088 nm. A new reference solar spectrum is therefore obtained in this mainly infrared wavelength range (656 to 3088 nm); it uses an absolute preflight calibration performed with the blackbody of the Physikalisch-Technische Bundesanstalt (PTB). An improved correction of temperature effects is also applied to the measurements using in-flight housekeeping temperature data of the instrument. The new solar spectrum (SOLAR–IR) is in good agreement with the ATmospheric Laboratory for Applications and Science (ATLAS 3) reference solar spectrum from 656 nm to about 1600 nm. However, above 1600 nm, it agrees better with solar reconstruction models than with spacecraft measurements. The new SOLAR/SOLSPEC measurement of solar spectral irradiance at about 1600 nm, corresponding to the minimum opacity of the solar photosphere, is 248.08 ± 4.98 mW m−2 nm−1 (1 $\sigma$ ), which is higher than recent ground-based evaluations.

Published
2017

226. Thermal structure of the upper atmosphere of Venus simulated by a ground-to-thermosphere GCM

Author

François Lott, Gabriella Gilli, Jean-Yves Chaufray, Francisco Gonzalez-Galindo, Miguel Lopez-Valverde, Franck Lefèvre, Sébastien Lebonnois, Aurélien Stolzenbach, Laboratoire de Météorologie Dynamique (UMR 8539) (LMD), Département des Géosciences - ENS Paris, École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-École des Ponts ParisTech (ENPC)-École polytechnique (X)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC), Instituto de Astrofísica de Andalucía (IAA), Consejo Superior de Investigaciones Científicas [Madrid] (CSIC), PLANETO - LATMOS, Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), HELIOS - LATMOS, Spanish MINECO, Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-École des Ponts ParisTech (ENPC)-Centre National de la Recherche Scientifique (CNRS)-Département des Géosciences - ENS Paris, École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-École normale supérieure - Paris (ENS-PSL), and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)

Subjects
Daytime, 010504 meteorology & atmospheric sciences, biology, [SDU.ASTR.EP]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Earth and Planetary Astrophysics [astro-ph.EP], Astronomy and Astrophysics, Venus, Atmospheric sciences, biology.organism_classification, 01 natural sciences, Mesosphere, Atmosphere of Venus, Atmosphere, Depth sounding, 13. Climate action, Space and Planetary Science, Planet, 0103 physical sciences, Environmental science, Thermosphere, 010303 astronomy & astrophysics, 0105 earth and related environmental sciences
Abstract

International audience; We present here the thermal structure of the upper atmosphere of Venus predicted by a full self-consistent Venus General Circulation Model (VGCM) developed at Laboratoire de MMétéorologie Dynamique (LMD) and extended up to the thermosphere of the planet. Physical and photochemical processes relevant at those altitudes, plus a non-orographic GW parameterisation, have been added. All those improvements make the LMD-VGCM the only existing ground-to-thermosphere 3D model for Venus: a unique tool to investigate the atmosphere of Venus and to support the exploration of the planet by remote sounding. The aim of this paper is to present the model reference results, to describe the role of radiative, photochemical and dynamical effects in the observed thermal structure in the upper mesosphere/lower thermosphere of the planet. The predicted thermal structure shows a succession of warm and cold layers, as recently observed. A cooling trend with increasing latitudes is found during daytime at all altitudes, while at nighttime the trend is inverse above about 110 km, with an atmosphere up to 15 K warmer towards the pole. The latitudinal variation is even smaller at the terminator, in agreement with observations. Below about 110 km, a nighttime warm layer whose intensity decreases with increasing latitudes is predicted by our GCM. A comparison of model results with a selection of recent measurements shows an overall good agreement in terms of trends and order of magnitude. Significant data-model discrepancies may be also discerned. Among them, thermospheric temperatures are about 40-50 K colder and up to 30 K warmer than measured at terminator and at nighttime, respectively. The altitude layer of the predicted mesospheric local maximum (between 100 and 120 km) is also higher than observed. Possible interpretations are discussed and several sensitivity tests performed to understand the data-model discrepancies and to propose future model improvements.

Published
2017

227. Coronal mass ejections and solar wind mass fluxes over the heliosphere during solar cycles 23 and 24 (1996-2014)

Author

Olivier Floyd, Bice Boclet, Eric Quémerais, Stéphane Ferron, Philippe Lamy, Laboratoire d'Astrophysique de Marseille (LAM), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Aix Marseille Université (AMU)-Centre National d'Études Spatiales [Toulouse] (CNES), AKKA Technologies, HELIOS - LATMOS, Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Analytic and Computational Research, Inc. - Earth Sciences (ACRI-ST), and Aix Marseille Université (AMU)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Physics, Mass flux, 010504 meteorology & atmospheric sciences, [SDU.ASTR.SR]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Solar and Stellar Astrophysics [astro-ph.SR], Solar wind, Astronomy, Coronal loop, Solar maximum, 01 natural sciences, Corona, Solar cycle, Geophysics, 13. Climate action, Space and Planetary Science, 0103 physical sciences, Coronal mass ejection, 010303 astronomy & astrophysics, Heliosphere, 0105 earth and related environmental sciences
Abstract

International audience; Coronal mass ejections (CMEs) play a major role in the heliosphere and their contribution to the solar wind mass flux, already considered in the Skylab and Solwind eras with conflicting results, is re-examined in the light of 19 years (1996-2014) of SOHO observations with the Large Angle and Spectroscopic Coronagraph “LASCO-C2” for the CMEs and extended for the first time to all latitudes thanks to the whole-heliosphere data from the Solar Wind ANisotropies “SWAN” instrument supplemented by in-situ data aggregated in the OMNI database. First, several mass estimates reported in the ARTEMIS catalog of LASCO CMEs are compared with determinations based on the combined observations with the twin STEREO/SECCHI coronagraphs in order to ascertain their validity. A simple geometric model of the CMEs is introduced to generate Carrington maps of their mass flux and then to produce annualized synoptic maps. The Lyman-α SWAN data are inverted to similarly produce synoptic maps to be compared with those of the CME flux. The ratio of the annualized CME to solar wind mass flux is found to closely track the solar cycle over the heliosphere. In the near-ecliptic region and at latitudes up to ∼ 55o, this ratio was negligibly small during the solar minima of cycles 22/23 and 23/24 and rose to 6% and 5% respectively at the maximum of solar cycles 23 and 24. These maximum ratios increased at higher latitudes but this result is likely biased by the inherent limitation of determining the true latitude of CMEs.

Published
2017

228. On the orbital variability of Ganymede's atmosphere

Author

Ludivine Leclercq, Apurva Oza, T. A. Cassidy, Robert E. Johnson, Carl Schmidt, Jean-Yves Chaufray, François Leblanc, Ronan Modolo, HELIOS - LATMOS, Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), University of Virginia, Laboratory for Atmospheric and Space Physics [Boulder] (LASP), University of Colorado [Boulder], ANR-09-BLAN-0223,HELIOSARES,Relation Soleil ? Mars: description et analyse des échanges présents et passés entre magnétosphère et atmosphère(2009), and University of Virginia [Charlottesville]

Subjects
Rotation period, 010504 meteorology & atmospheric sciences, Terminator (solar), Equator, [SDU.ASTR.EP]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Earth and Planetary Astrophysics [astro-ph.EP], FOS: Physical sciences, 01 natural sciences, Jovian, Astrobiology, Jupiter, Atmosphere, 0103 physical sciences, 010303 astronomy & astrophysics, 0105 earth and related environmental sciences, Earth and Planetary Astrophysics (astro-ph.EP), Physics, [SDU.ASTR.SR]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Solar and Stellar Astrophysics [astro-ph.SR], Astronomy, Astronomy and Astrophysics, Solar wind, 13. Climate action, Space and Planetary Science, Physics::Space Physics, Astrophysics::Earth and Planetary Astrophysics, Astrophysics - Earth and Planetary Astrophysics, Exosphere
Abstract

Ganymede's atmosphere is produced by radiative interactions with its surface, sourced by the Sun and the Jovian plasma. The sputtered and thermally desorbed molecules are tracked in our Exospheric Global Model (EGM), a 3-D parallelized collisional model. This program was developed to reconstruct the formation of the upper atmosphere/exosphere of planetary bodies interacting with solar photon flux and magnetospheric and/or the solar wind plasmas. Here, we describe the spatial distribution of the H$_2$O and O$_2$ components of Ganymede's atmosphere, and their temporal variability along Ganymede's rotation around Jupiter. In particular, we show that Ganymede's O$_2$ atmosphere is characterized by time scales of the order of Ganymede's rotational period with Jupiter's gravity being a significant driver of the spatial distribution of the heaviest exospheric components. Both the sourcing and the Jovian gravity are needed to explain some of the characteristics of the observed aurora emissions. As an example, the O$_2$ exosphere should peak at the equator with systematic maximum at the dusk equator terminator. The sputtering rate of the H$_2$O exosphere should be maximum on the leading hemisphere because of the shape of the open/close field lines boundary and displays some significant variability with longitude., 14 pages, 9 figures, Accepted to Icarus

Published
2017

229. Two-stream instabilities from the lower-hybrid frequency to the electron cyclotron frequency: application to the front of quasi-perpendicular shocks

Author

Muschietti, Laurent, Lembège, Bertrand, Space Sciences Laboratory [Berkeley] (SSL), University of California [Berkeley], University of California-University of California, HELIOS - LATMOS, Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), University of California [Berkeley] (UC Berkeley), and University of California (UC)-University of California (UC)

Subjects
Physics::Plasma Physics, [SDU.STU.GP]Sciences of the Universe [physics]/Earth Sciences/Geophysics [physics.geo-ph], [PHYS.PHYS.PHYS-PLASM-PH]Physics [physics]/Physics [physics]/Plasma Physics [physics.plasm-ph], plasma waves and instabilities, Physics::Space Physics, wave–particle interactions, Interplanetary physics, space plasma physics, [PHYS.PHYS.PHYS-SPACE-PH]Physics [physics]/Physics [physics]/Space Physics [physics.space-ph], planetary bow shocks, magnetospheric physics
Abstract

Quasi-perpendicular supercritical shocks are characterized by the presence of a magnetic foot due to the accumulation of a fraction of the incoming ions that is reflected by the shock front. There, three different plasma populations coexist (incoming ion core, reflected ion beam, electrons) and can excite various two-stream instabilities (TSIs) owing to their relative drifts. These instabilities represent local sources of turbulence with a wide frequency range extending from the lower hybrid to the electron cyclotron. Their linear features are analyzed by means of both a dispersion study and numerical PIC simulations. Three main types of TSI and correspondingly excited waves are identified: i. Oblique whistlers due to the (so-called fast) relative drift between reflected ions/electrons; the waves propagate toward upstream away from the shock front at a strongly oblique angle (θ ∼ 50°) to the ambient magnetic field Bo, have frequencies a few times the lower hybrid, and have wavelengths a fraction of the ion inertia length c∕ωpi. ii. Quasi-perpendicular whistlers due to the (so-called slow) relative drift between incoming ions/electrons; the waves propagate toward the shock ramp at an angle θ a few degrees off 90°, have frequencies around the lower hybrid, and have wavelengths several times the electron inertia length c∕ωpe. iii. Extended Bernstein waves which also propagate in the quasi-perpendicular domain, yet are due to the (so-called fast) relative drift between reflected ions/electrons; the instability is an extension of the electron cyclotron drift instability (normally strictly perpendicular and electrostatic) and produces waves with a magnetic component which have frequencies close to the electron cyclotron as well as wavelengths close to the electron gyroradius and which propagate toward upstream. Present results are compared with previous works in order to stress some features not previously analyzed and to define a more synthetic view of these TSIs.

Published
2017

230. A new solar reference spectrum from 165 to 3088 nm

Author

Damé, Luc, Meftah, Mustapha, Bolsée, David, Pereira, Nuno, Bekki, Slimane, Hauchecorne, Alain, Irbah, Abdanour, Cessateur, Gaël, Sluse, Dominique, Cardon, Catherine, HELIOS - LATMOS, Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), STRATO - LATMOS, and Belgian Institute for Space Aeronomy / Institut d'Aéronomie Spatiale de Belgique (BIRA-IASB)

Subjects
[SDU.ASTR.SR]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Solar and Stellar Astrophysics [astro-ph.SR], [SDU.ASTR.SR] Sciences of the Universe [physics]/Astrophysics [astro-ph]/Solar and Stellar Astrophysics [astro-ph.SR]
Abstract

International audience; Since April 5, 2008 and until February 15, 2017 the SOLAR/SOLSPEC spectro-radiometer on the International Space Station performed accurate measurements of Solar Spectral Irradiance (SSI) from the far ultraviolet to the infrared (165 nm to 3088 nm). These measurements are of primary importance for a better understanding of solar physics and of the impact of solar variability on climate (via Earth's atmospheric photochemistry). In particular, a new reference solar spectrum is established covering most of the unusual solar cycle 24 from minimum in 2008 to maximum. Temporal variability in the UV (165 to 400 nm) is presented in several wavelengths bands. These results are possible thanks to revised engineering corrections, improved calibrations and new procedures to account for thermal and aging advanced corrections. Uncertainties on these measurements are evaluated and compare favorably with other instruments.

Published
2017

231. On the Origins of Mars' Exospheric Nonthermal Oxygen Component as Observed by MAVEN and Modeled by HELIOSARES

Author

Leblanc, François, Chaufray, Jean-Yves, Modolo, Ronan, Leclercq, Ludivine, Curry, S., Luhmann, J., Lillis, R., Hara, T., Mcfadden, J., Halekas, J., Schneider, N., Deighan, Justin, Mahaffy, P. R., Benna, M., Johnson, R. E., Gonzalez-Galindo, F., Forget, François, López-Valverde, M. A., Eparvier, F. G., Jakosky, B., HELIOS - LATMOS, Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Department of Materials Science and Engineering [Charlottesville] (MS), University of Virginia [Charlottesville], Space Sciences Laboratory [Berkeley] (SSL), University of California [Berkeley], University of California-University of California, Department of Physics and Astronomy [Ames, Iowa], Iowa State University (ISU), Laboratory for Atmospheric and Space Physics [Boulder] (LASP), University of Colorado [Boulder], NASA Goddard Space Flight Center (GSFC), Instituto de Astrofísica de Andalucía (IAA), Consejo Superior de Investigaciones Científicas [Madrid] (CSIC), Laboratoire de Météorologie Dynamique (UMR 8539) (LMD), Département des Géosciences - ENS Paris, École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-École des Ponts ParisTech (ENPC)-École polytechnique (X)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC), Agence Nationale de la Recherche (ANR), ANR-09-BLAN-0223,HELIOSARES,Relation Soleil ? Mars: description et analyse des échanges présents et passés entre magnétosphère et atmosphère(2009), University of Virginia, University of California [Berkeley] (UC Berkeley), University of California (UC)-University of California (UC), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-École des Ponts ParisTech (ENPC)-Centre National de la Recherche Scientifique (CNRS)-Département des Géosciences - ENS Paris, École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-École normale supérieure - Paris (ENS-PSL), and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)

Subjects
[SDU.STU.GP]Sciences of the Universe [physics]/Earth Sciences/Geophysics [physics.geo-ph], MAVEN, Exosphere, Mars' atmospheric escape
Abstract

International audience; The first measurements of the emission brightness of the oxygen atomic exosphere by Mars Atmosphere and Volatile EvolutioN (MAVEN) mission have clearly shown that it is composed of a thermal component produced by the extension of the upper atmosphere and of a non-thermal component. Modeling these measurements allows us to constrain the origins of the exospheric O and, as a consequence, to estimate Mars' present oxygen escape rate. We here propose an analysis of three periods of MAVEN observations based on a set of three coupled models: a hybrid magnetospheric model (LatHyS), an Exospheric General Model (EGM) and the Global Martian Circulation model of the Laboratoire de Météorologie Dynamique (LMD-GCM), which provide a description of Mars' environment from the surface up to the solar wind. The simulated magnetosphere by LatHyS is in good agreement with MAVEN Plasma and Field Package instruments data. The LMD-GCM modeled upper atmospheric profiles for the main neutral and ion species are compared to NGIMS/MAVEN data showing that the LMD-GCM can provide a satisfactory global view of Mars' upper atmosphere. Finally, we were able to reconstruct the expected emission brightness intensity from the oxygen exosphere using EGM. The good agreement with the averaged measured profiles by IUVS during these three periods suggests that Mars' exospheric non-thermal component can be fully explained by the reactions of dissociative recombination of the O2+ ion in Mars' ionosphere, limiting significantly our ability to extract information from MAVEN observations of the O exosphere on other non-thermal processes, such as sputtering.

Published
2017

232. Electrostatic analyzer with a 3-D instantaneous field of view for fast measurements of plasma distribution functions in space

Author

Matthieu Berthomier, Xavier Morel, Jean-Jacques Berthelier, Laboratoire de Physique des Plasmas (LPP), Université Paris-Sud - Paris 11 (UP11)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-École polytechnique (X)-Sorbonne Université (SU)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), HELIOS - LATMOS, Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), CNES (RS10/SU-0004-036), and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-École polytechnique (X)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)

Subjects
Physics, Spectrum analyzer, 010504 meteorology & atmospheric sciences, business.industry, [SDU.ASTR.SR]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Solar and Stellar Astrophysics [astro-ph.SR], Solar wind, Field of view, Plasma, Curvature, 01 natural sciences, Charged particle, [SDU.ASTR.IM]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Instrumentation and Methods for Astrophysic [astro-ph.IM], Electrostatic Analyzer, Geophysics, Angular aperture, Optics, Distribution function, Space and Planetary Science, Magnetosphere, 0103 physical sciences, Space plasma instrument, business, Electrostatic analyzer, 010303 astronomy & astrophysics, 0105 earth and related environmental sciences
Abstract

International audience; We describe the concept and properties of a new electrostatic optic which aims to provide a 2π sr instantaneous field-of-view to characterize space plasmas. It consists of a set of concentric toroidal electrodes that form a number of independent energy selective channels. Charged particles are deflected towards a common imaging planar detector. The full 3D distribution function of charged particles is obtained through a single energy sweep. Angle and energy resolution of the optics depends on the number of toroidal electrodes, on their radii of curvature, on their spacing, and on the angular aperture of the channels. We present the performances, as derived from numerical simulations, of an initial implementation of this concept that would fit the need of many space plasma physics applications. The proposed instrument has 192 entrance windows corresponding to 8 polar channels each with 24 azimuthal sectors. The initial version of this 3D plasma analyzer may cover energies from a few eV up to 30 keV, typically with a channel dependent energy resolution varying from 10% to 7%. The angular acceptance varies with the direction of the incident particle from 3° to 12°. With a total geometric factor of two sensor heads reaching ~ 0.23 cm2 · sr · eV/eV, this “donut” shape analyzer has enough sensitivity to allow very fast measurements of plasma distribution functions in most terrestrial and planetary environments on three-axis stabilized as well as on spinning satellites.

Published
2017

233. Europa and Ganymede's Water-Product Exospheres

Author

Oza, Apurva V., Leblanc, François, Chaufray, Jean-Yves, Schmidt, Carl, Roth, L., Johnson, R. E., Cassidy, T.A., Leclercq, L., Modolo, Ronan, Cardon, Catherine, HELIOS - LATMOS, Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), PLANETO - LATMOS, Boston University [Boston] (BU), Royal Institute of Technology [Stockholm] (KTH ), Department of Materials Science and Engineering [Charlottesville] (MS), University of Virginia, Department of Physics [New York], New York University [New York] (NYU), NYU System (NYU)-NYU System (NYU), Department of Astronomy [Charlottesville], Laboratory for Atmospheric and Space Physics [Boulder] (LASP), University of Colorado [Boulder], Engineering Physics Program [Charlottesville], and University of Virginia [Charlottesville]

Subjects
[SDU] Sciences of the Universe [physics], [SDU]Sciences of the Universe [physics]
Abstract

International audience; Europa and Ganymede are thought to possess globally similar exospheres, in spite of the possibility that Europa is currently cryovolcanically active, and Ganymede's intrinsic magnetic field. Ions in Jupiter's magnetosphere bombard the icy surfaces, and produce predominantly O2, with slightly less H2O and H2 due to freezing and escape respectively. We investigate and compare the water-product exospheres of the two satellites under rotation, using our 3-D Exosphere Global Model (EGM). In previous works ([1], [2]), we focused on the near-surface z < 1.25rs , oxidized component of the exosphere, dominated by thermal-ized O2 , which undergoes a dusk-over-dawn asymmetry due to diurnal solar insolation of the surface over the satellite's orbit. This was observed by asymmetries in oxygen aurorae. Here, we focus on characterizing the hydrogen-species: H, H2 , and H2O which have been far more elusive as lyman-α auroral emission has multiple production pathways, even in the absence of endogenic sources.

Published
2017

234. Photochemical escape of oxygen from Mars: first results from MAVEN in situ data

Author

James P. McFadden, Bruce M. Jakosky, Jane L. Fox, Jasper Halekas, Meredith Elrod, Stephen W. Bougher, Robert Lillis, Yuni Lee, J. Y. Chaufray, François Leblanc, Mehdi Benna, Ali Rahmati, Justin Deighan, Christopher M. Fowler, Paul R. Mahaffy, Edward Thiemann, Robert E. Ergun, Michael R. Combi, Laila Andersson, Frank Eparvier, Thomas E. Cravens, Space Sciences Laboratory [Berkeley] (SSL), University of California [Berkeley], University of California-University of California, Laboratory for Atmospheric and Space Physics [Boulder] (LASP), University of Colorado [Boulder], Department of Physics [Dayton], Wright State University, Department of Climate and Space Sciences and Engineering (CLaSP), University of Michigan [Ann Arbor], University of Michigan System-University of Michigan System, Department of Physics and Astronomy [Lawrence Kansas], University of Kansas [Lawrence] (KU), NASA Goddard Space Flight Center (GSFC), Department of Physics and Astronomy [Iowa City], University of Iowa [Iowa City], HELIOS - LATMOS, Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), University of California [Berkeley] (UC Berkeley), and University of California (UC)-University of California (UC)

Subjects
Solar System, 010504 meteorology & atmospheric sciences, Solar zenith angle, Mars, Atmospheric sciences, Photochemistry, 01 natural sciences, Atmosphere, 0103 physical sciences, 010303 astronomy & astrophysics, Dissociative recombination, 0105 earth and related environmental sciences, Martian, Atmospheric escape, Photochemical, Atmosphere of Mars, Mars Exploration Program, Dissociative, [PHYS.PHYS.PHYS-SPACE-PH]Physics [physics]/Physics [physics]/Space Physics [physics.space-ph], Oxygen, Geophysics, Escape, 13. Climate action, Space and Planetary Science, Environmental science
Abstract

International audience; Photochemical escape of atomic oxygen is thought to be one of the dominant channels for Martian atmospheric loss today and played a potentially major role in climate evolution. MAVEN is the first mission capable of measuring, in situ, the relevant quantities necessary to calculate photochemical escape fluxes. We utilize 18 months of data from three MAVEN instruments: LPW, NGIMS and STATIC. From these data we calculate altitude profiles of the production rate of hot oxygen atoms from the dissociative recombination (DR) of O2+ and the probability that such atoms will escape the Mars atmosphere. From this we determine escape fluxes for 815 periapsis passes. Derived average dayside hot O escape rates range from 1.2 to 5.5 x 1025 s-1 depending on season and EUV flux, consistent with several pre-MAVEN predictions and in broad agreement with estimates made with other MAVEN measurements. Hot O escape fluxes do not vary significantly with dayside solar zenith angle or crustal magnetic field strength, but depend on CO2 photoionization frequency with a power law whose exponent is 2.6 ± 0.6, an unexpectedly high value which may be partially due to seasonal and geographic sampling. From this dependence and historical EUV measurements over 70 years, we estimate a modern-era average escape rate of 4.3 x 1025 s-1. Extrapolating this dependence to early solar system EUV conditions gives total losses of 13, 49, 189, and 483 mb of oxygen over 1, 2, 3, and 3.5 Gyr respectively, with uncertainties significantly increasing with time in the past.

Published
2017

235. MAVEN and the total electron content of the Martian ionosphere

Author

Paul R. Mahaffy, František Němec, Bruce A. Campbell, Michael Mendillo, François Forget, Majd Mayyasi, Francisco Gonzalez-Galindo, François Leblanc, Miguel Lopez-Valverde, Marissa F. Vogt, Laila Andersson, Y. J. Ma, Mehdi Benna, Jean-Yves Chaufray, Bruce M. Jakosky, Clara Narvaez, Center for Space Physics [Boston] (CSP), Boston University [Boston] (BU), NASA Goddard Space Flight Center (GSFC), Laboratory for Atmospheric and Space Physics [Boulder] (LASP), University of Colorado [Boulder], Smithsonian Institution, Faculty of Mathematics and Physics [Praha/Prague], Charles University [Prague] (CU), University of California [Los Angeles] (UCLA), University of California, HELIOS - LATMOS, Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Instituto de Astrofísica de Andalucía (IAA), Consejo Superior de Investigaciones Científicas [Madrid] (CSIC), Laboratoire de Météorologie Dynamique (UMR 8539) (LMD), Département des Géosciences - ENS Paris, École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-École des Ponts ParisTech (ENPC)-École polytechnique (X)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC), University of California (UC), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-École des Ponts ParisTech (ENPC)-Centre National de la Recherche Scientifique (CNRS)-Département des Géosciences - ENS Paris, École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-École normale supérieure - Paris (ENS-PSL), and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)

Subjects
Martian, Physics, Electron density, Daytime, 010504 meteorology & atmospheric sciences, Total electron content, TEC, MAVEN, Mars, Mars Exploration Program, Atmospheric sciences, 01 natural sciences, [PHYS.PHYS.PHYS-SPACE-PH]Physics [physics]/Physics [physics]/Space Physics [physics.space-ph], Geophysics, 13. Climate action, Space and Planetary Science, 0103 physical sciences, Ionosphere, 010303 astronomy & astrophysics, Zenith, 0105 earth and related environmental sciences
Abstract

International audience; Model studies of the ionosphere of Mars under daytime conditions reveal that for solar zenith angles (SZAs) of 0°-40°, the shapes and magnitudes of the electron density profiles Ne(h) change by only small amounts. This suggests that mid-day observations made by MAVEN instruments along slanted orbit segments can be used to represent vertical profiles. The total electron content (TEC), defined as the height integral of Ne(h), is a measure of the cold plasma reservoir of the martian ionosphere. During MAVEN's Deep-Dip-#2 campaign of April 2015, observations of total ion density by NGIMS and electron density by LPW from periapse (~130 km) to 400 km were used to form topside—validated by independent diagnostics and models. Orbit-by-orbit changes in topside TEC were then used to assess the magnitudes of plasma escape associated with both large and small changes in the topside slope of Ne(h)—called an “ionopause episode.” The TEC changes due to these episodes, generalized to a global change, resulted in an escape flux of ~3 - 6 x 1024 ions/sec, an escape rate consistent with prior observation by Phobos-2, Mars Express, and MAVEN's own in-situ studies.

Published
2017

236. Evidence for depletion of heavy silicon isotopes at comet 67P/Churyumov-Gerasimenko

Author

Sébastien Gasc, Martin Rubin, André Bieler, Jean-Jacques Berthelier, Michael R. Combi, Cécile Engrand, Hans Balsiger, Klaus Mezger, Chia-Yu Tzou, Kenneth C. Hansen, Björn Fiethe, Myrtha Hässig, Peter Wurz, Ursina Calmonte, Kathrin Altwegg, S. A. Fuselier, Léna Le Roy, Tamas I. Gombosi, J. De Keyser, Susanne F. Wampfler, Physikalisches Institut [Bern], Universität Bern [Bern], Center for Space and Habitability (CSH), University of Bern, HELIOS - LATMOS, Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Department of Atmospheric, Oceanic, and Space Sciences [Ann Arbor] (AOSS), University of Michigan [Ann Arbor], University of Michigan System-University of Michigan System, Department of Climate and Space Sciences and Engineering (CLaSP), Belgian Institute for Space Aeronomy / Institut d'Aéronomie Spatiale de Belgique (BIRA-IASB), Centre de Sciences Nucléaires et de Sciences de la Matière (CSNSM), Université Paris-Sud - Paris 11 (UP11)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Institute of Computer and Network Engineering [Braunschweig] (IDA), Technische Universität Braunschweig = Technical University of Braunschweig [Braunschweig], UTSA Department of Physics and Astronomy [San Antonio], The University of Texas at San Antonio (UTSA), Southwest Research Institute [San Antonio] (SwRI), Institut für Geologie [Bern], Center for Space and Habitability ( CSH ), HEPPI - LATMOS, Laboratoire Atmosphères, Milieux, Observations Spatiales ( LATMOS ), Université de Versailles Saint-Quentin-en-Yvelines ( UVSQ ) -Université Pierre et Marie Curie - Paris 6 ( UPMC ) -Institut national des sciences de l'Univers ( INSU - CNRS ) -Centre National de la Recherche Scientifique ( CNRS ) -Université de Versailles Saint-Quentin-en-Yvelines ( UVSQ ) -Université Pierre et Marie Curie - Paris 6 ( UPMC ) -Institut national des sciences de l'Univers ( INSU - CNRS ) -Centre National de la Recherche Scientifique ( CNRS ), Department of Atmospheric, Oceanic, and Space Sciences [Ann Arbor] ( AOSS ), Department of Climate and Space Sciences and Engineering ( CLaSP ), Belgian Institute for Space Aeronomy / Institut d'Aéronomie Spatiale de Belgique ( BIRA-IASB ), Centre de Sciences Nucléaires et de Sciences de la Matière ( CSNSM AS ), Université Paris-Saclay-Univ. Paris-Sud-CNRS/IN2P3, Institute of Computer and Network Engineering [Braunschweig] ( IDA ), Technische Universität Braunschweig [Braunschweig], The University of Texas at San Antonio ( UTSA ), Southwest Research Institute [San Antonio] ( SwRI ), Universität Bern [Bern] (UNIBE), and Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Paris-Sud - Paris 11 (UP11)

Subjects
Solar System, Astrochemistry, 010504 meteorology & atmospheric sciences, Comet, Analytical chemistry, FOS: Physical sciences, Context (language use), Astrophysics, 01 natural sciences, 0103 physical sciences, Isotopes of silicon, 010303 astronomy & astrophysics, Solar and Stellar Astrophysics (astro-ph.SR), 0105 earth and related environmental sciences, Earth and Planetary Astrophysics (astro-ph.EP), Physics, [PHYS.PHYS.PHYS-AO-PH]Physics [physics]/Physics [physics]/Atmospheric and Oceanic Physics [physics.ao-ph], Spectrometer, Astronomy and Astrophysics, Solar wind, Meteorite, Astrophysics - Solar and Stellar Astrophysics, [ PHYS.PHYS.PHYS-AO-PH ] Physics [physics]/Physics [physics]/Atmospheric and Oceanic Physics [physics.ao-ph], 13. Climate action, Space and Planetary Science, Astrophysics - Earth and Planetary Astrophysics
Abstract

Context. The Rosetta Orbiter Spectrometer for Ion and Neutral Analysis (ROSINA) was designed to measure the composition of the gas in the coma of comet 67P/Churyumov-Gerasimenko, the target of the European Space Agency's Rosetta mission. In addition to the volatiles, ROSINA measured refractories sputtered off the comet by the interaction of solar wind protons with the surface of the comet. Aims. The origin of different solar system materials is still heavily debated. Isotopic ratios can be used to distinguish between different reservoirs and investigate processes occurring during the formation of the solar system. Methods. ROSINA consisted of two mass spectrometers and a pressure sensor. In the ROSINA Double Focusing Mass Spectrometer (DFMS), the neutral gas of cometary origin was ionized and then deflected in an electric and a magnetic field that separated the ions based on their mass-to-charge ratio. The DFMS had a high mass resolution, dynamic range, and sensitivity that allowed detection of rare species and the known major volatiles. Results. We measured the relative abundance of all three stable silicon isotopes with the ROSINA instrument on board the Rosetta spacecraft. Furthermore, we measured $^{13}$C/$^{12}$C in C$_2$H$_4$, C$_2$H$_5$, and CO. The DFMS in situ measurements indicate that the average silicon isotopic composition shows depletion in the heavy isotopes $^{29}$Si and $^{30}$Si with respect to $^{28}$Si and solar abundances, while $^{13}$C to $^{12}$C is analytically indistinguishable from bulk planetary and meteorite compositions. Although the origin of the deficiency of the heavy silicon isotopes cannot be explained unambiguously, we discuss mechanisms that could have contributed to the measured depletion of the isotopes $^{29}$Si and $^{30}$Si., Accepted for publication in Astronomy & Astrophysics

Published
2017

237. Are large organic molecules in comets similar to the Diffuse Interstellar Bands carriers?

Author

Bertaux, Jean-Loup, Lallement, Rosine, HELIOS - LATMOS, Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Galaxies, Etoiles, Physique, Instrumentation (GEPI), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS)

Subjects
[SDU]Sciences of the Universe [physics]
Abstract

International audience; We suggest that the refractory organic material found by COSIMA in 67P/CG comet dust (Fray et al., 2016) is made of aggregates of the same organic molecules which are present in the interstellar medium (ISM) and are producing in observed stellar spectra the absorptions called Diffuse Interstellar Bands (DIBs). Such a link would increase the scientific interest of a comet sample return mission, addressing both comets and interstellar material. The refractory character of comet organic matter does not necessitate a cooled return capsule, an important sample return mission cost-driver.

Published
2017

238. Global structure and sodium ion dynamics in Mercury's magnetosphere with the offset dipole

Author

Yosuke Matsumoto, Dominique Delcourt, Manabu Yagi, Kanako Seki, François Leblanc, RIKEN Center for Computational Science [Kobe] (RIKEN CCS), RIKEN - Institute of Physical and Chemical Research [Japon] (RIKEN), Department of Earth and Planetary Science [Tokyo], Graduate School of Science [Tokyo], The University of Tokyo (UTokyo)-The University of Tokyo (UTokyo), Graduate School of Science [Chiba], Chiba University, Laboratoire de Physique des Plasmas (LPP), Université Paris-Saclay-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris-Sud - Paris 11 (UP11)-École polytechnique (X)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL), HELIOS - LATMOS, Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS), Sorbonne Université (SU)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS), and The University of Tokyo (UTokyo)

Subjects
Physics, 010504 meteorology & atmospheric sciences, Plasma sheet, Magnetosphere, Geophysics, 01 natural sciences, [PHYS.PHYS.PHYS-SPACE-PH]Physics [physics]/Physics [physics]/Space Physics [physics.space-ph], Solar wind, Magnetosheath, 13. Climate action, Space and Planetary Science, Magnetosphere of Saturn, 0103 physical sciences, Physics::Space Physics, Magnetopause, Astrophysics::Earth and Planetary Astrophysics, Atomic physics, Interplanetary magnetic field, Mercury's magnetic field, 010303 astronomy & astrophysics, Physics::Atmospheric and Oceanic Physics, 0105 earth and related environmental sciences
Abstract

Dominique Delcourt : Present address : Director LPC2E UMR 7328 CNRS Orléans France; International audience; We conducted global magnetohydrodynamics (MHD) simulation of Mercury's magnetosphere with the dipole offset, which was revealed by MESSENGER observations, in order to investigate its global structure under northward interplanetary magnetic field (IMF) conditions. Sodium ion dynamics originating from the Mercury's exosphere is also investigated based on statistical trajectory tracing in the electric and magnetic fields obtained from the MHD simulations. The results reveal a north-south asymmetry characterized by open field lines around southern polar region, and northward deflection of the plasma sheet in the far tail. The asymmetry of magnetic field structure near the planet drastically affects trajectories of sodium ion, and thus, their pressure distributions and precipitation pattern onto the planet. Weaker magnetic field strength in the southern hemisphere than in the north increases ion loss by precipitation onto the planetary surface in the southern hemisphere. The ‘sodium ring', which is formed by high-energy sodium ions drifting around the planet, is also found in the vicinity of the planet. The 'sodium ring' is almost circular under nominal solar wind conditions. The ring becomes partial under high solar wind density, because dayside magnetosphere is so compressed that there is no space for the sodium ions to drift around. In both cases, the 'sodium ring' is formed by sodium ions that are picked up and accelerated in the magnetosheath just outside the magnetopause and reentered into the magnetosphere due to combined effects of finite Larmor radius and convection electric field in the dawn-side magnetosphere.

Published
2017

239. Detection of Mercury's Potassium Tail

Author

Schmidt, Carl, Leblanc, François, Moore, Luke, Bida, Thomas A., Cardon, Catherine, Boston University [Boston] (BU), HELIOS - LATMOS, Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Center for Space Physics [Boston] (CSP), and Lowell Observatory [Flagstaff]

Subjects
[SDU] Sciences of the Universe [physics], [SDU]Sciences of the Universe [physics]
Abstract

International audience; Ground-based observations of Mercury's exosphere bridge the gap between the MESSENGER and BepiColombo missions and provide a broad counterpart to their in situ measurements. Here we report the first detection of Mercury's potassium tail in both emission lines of the D doublet. The sodium to potassium abundance ratio at 5 planetary radii down-tail is approximately 95, near the mid-point of a wide range of values that have been quoted over the planet's disk. This is several times the Na/K present in atmospheres of the Galilean satellites and more than an order of magnitude above Mercury's usual analogue, the Moon. The observations confirm that Mercury's anomalously high Na/K ratios cannot be explained by differences in neutral loss rates. The width and structure of the Na and K tails is comparable and both exhibit a persistent enhancement in their northern lobe. We interpret this as a signature of Mercury's offset magnetosphere; the exosphere's source rates are locally enhanced at the southern surface, and sloshing from radiation pressure and gravity guides this population into the northern region of the tail.

Published
2017

240. What we can learn from measurements of air electric conductivity in 222Rn-rich atmosphere

Author

Seran, Elena, Godefroy, Michel, Pili, Éric, Michielsen, Nathalie, Bondiguel, Sylvain, HELIOS - LATMOS, Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Direction des Applications Militaires (DAM), Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Laboratoire de Physique et de Métrologie des Aérosols (DSU/SERAC/LPMA), Institut de Radioprotection et de Sûreté Nucléaire (IRSN), Centre National d'Etudes Spatiales (CNES), and Laboratoire de Physique et de Métrologie des Aérosols (IRSN/DSU/SERAC/LPMA)

Subjects
[PHYS.PHYS.PHYS-AO-PH]Physics [physics]/Physics [physics]/Atmospheric and Oceanic Physics [physics.ao-ph], [SDU.ASTR.IM]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Instrumentation and Methods for Astrophysic [astro-ph.IM]
Abstract

International audience; Electric conductivity of air is an important characteristic of the electric properties of an atmosphere. Testing instruments to measure electric conductivity ranging from ~10-13 to 10-9 S m-1 in natural conditions found in the Earth atmosphere is not an easy task. One possibility is to use stratospheric balloon flights; another (and a simpler one) is to look for terrestrial environments with significant radioactive decay. In this paper we present measurements carried out with different types of Conductivity Sensors in two 222Rn-rich environments, i.e. in the Roselend underground tunnel (French Alps) and in the IRSN BACCARA chamber. The concept of the Conductivity Sensor is based on the classical time relaxation method. New elements in our design include isolation of the sensor sensitive part (electrode) from the external electric field and sensor miniaturization. This greatly extends the application domain of the sensor and permits to measure air electric conductivity when the external electric field is high and varies from few tens of V m-1 to up to few tens of kV m-1. This is suitable to propose the instrument for a planetary mission. Two-fold objectives were attained as the outcome of these tests and their analysis. First was directly related to the performances of the Conductivity Sensors and the efficiency of the Conductivity Sensor design to shield the external electric field. Second objective aimed at understanding the decay mechanisms of 222Rn and its progeny in atmosphere and the impact of the enclosed space on the efficiency of gas ionization. This article is protected by copyright. All rights reserved.

Published
2017

241. Dynamics of aspherical dust grains in a cometary atmosphere: I. Axially symmetric grains in a spherically symmetric atmosphere

Author

Jean-François Crifo, Stavro Ivanovski, Alessandra Rotundi, Marco Fulle, V. V. Zakharov, V. Della Corte, Istituto di Astrofisica e Planetologia Spaziali - INAF (IAPS), Istituto Nazionale di Astrofisica (INAF), Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), HELIOS - LATMOS, Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Università degli Studi di Napoli 'Parthenope' = University of Naples (PARTHENOPE), INAF - Osservatorio Astronomico di Trieste (OAT), Italian Space Agency (ASI), and Universita degli studi di Napoli 'Parthenope' [Napoli]

Subjects
Physics, Range (particle radiation), 010504 meteorology & atmospheric sciences, Comet, Rotation around a fixed axis, [SDU.ASTR.EP]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Earth and Planetary Astrophysics [astro-ph.EP], Astronomy and Astrophysics, Dust, Aerodynamics, Mechanics, Astrophysics, 01 natural sciences, Dynamics, Atmosphere, Aerodynamic force, Interplanetary dust cloud, Space and Planetary Science, 0103 physical sciences, Comets, Coma, Astrophysics::Earth and Planetary Astrophysics, Axial symmetry, 010303 astronomy & astrophysics, 0105 earth and related environmental sciences
Abstract

International audience; In-situ measurements of individual dust grain parameters in the immediate vicinity of a cometary nucleus are being carried by the Rosetta spacecraft at comet 67P/Churyumov-Gerasimenko. For the interpretations of these observational data, a model of dust grain motion as realistic as possible is requested. In particular, the results of the Stardust mission and analysis of samples of interplanetary dust have shown that these particles are highly aspherical, which should be taken into account in any credible model. The aim of the present work is to study the dynamics of ellipsoidal shape particles with various aspect ratios introduced in a spherically symmetric expanding gas flow and to reveal the possible differences in dynamics between spherical and aspherical particles. Their translational and rotational motion under influence of the gravity and of the aerodynamic force and torque is numerically integrated in a wide range of physical parameters values including those of comet 67P/Churyumov-Gerasimenko. The main distinctions of the dynamics of spherical and ellipsoidal particles are discussed. The aerodynamic characteristics of the ellipsoidal particles, and examples of their translational and rotational motion in the postulated gas flow are presented

Published
2017

242. IUVS echelle-mode observations of interplanetary hydrogen: Standard for calibration and reference for cavity variations between Earth and Mars during MAVEN cruise

Author

Dolon Bhattacharyya, Nicholas M. Schneider, Majd Mayyasi, Jean-Loup Bertaux, Bill McClintock, Jean-Yves Chaufray, Bruce M. Jakosky, Greg Holsclaw, John Clarke, Michael Chaffin, Ian Stewart, Olga Katushkina, Eric Quémerais, Justin Deighan, Center for Space Physics [Boston] (CSP), Boston University [Boston] (BU), HELIOS - LATMOS, Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Space Research Institute of the Russian Academy of Sciences (IKI), Russian Academy of Sciences [Moscow] (RAS), Laboratory for Atmospheric and Space Physics [Boulder] (LASP), and University of Colorado [Boulder]

Subjects
010504 meteorology & atmospheric sciences, Mars, 01 natural sciences, 7. Clean energy, Atmospheric radiative transfer codes, 0103 physical sciences, Calibration, Echelle, 010303 astronomy & astrophysics, Spectrograph, 0105 earth and related environmental sciences, Physics, [PHYS.PHYS.PHYS-AO-PH]Physics [physics]/Physics [physics]/Atmospheric and Oceanic Physics [physics.ao-ph], Astronomy, Atmosphere of Mars, Mars Exploration Program, [PHYS.PHYS.PHYS-SPACE-PH]Physics [physics]/Physics [physics]/Space Physics [physics.space-ph], UV, Solar wind, Geophysics, 13. Climate action, Space and Planetary Science, Interplanetary spaceflight, IPH, Heliosphere
Abstract

International audience; The high-resolution echelle mode of the Imaging Ultraviolet Spectrograph (IUVS) instrument on the Mars Atmosphere and Volatile Evolution (MAVEN) mission has been designed to measure D and H Lyman-α emissions from the martian atmosphere to obtain key information about the physical processes by which water escapes into space. Toward this goal, the absolute calibration of the instrument is critical for determining the D and H densities, the D/H ratio, and the escape flux of water. The instrument made observations of interplanetary hydrogen (IPH) along multiple look directions and conducted several post-launch calibration campaigns during cruise as well as during orbit around Mars. The calibration efforts monitored instrument degradation and produced a consistent calibration factor at the hydrogen Lyman-α wavelength (121.567 nm). The instrument was calibrated with the diffuse emission of interplanetary hydrogen (IPH) as a standard candle using measurements and model results from the Solar Wind Anisotropies (SWAN) instrument. Validation of the calibrated instrument was made by (1) comparisons to simultaneous observations of the IPH made with the lower resolution FUV-mode of the IUVS instrument that were independently calibrated using standard stars as well as by (2) comparisons to same-day observations of Mars at hydrogen Lyman-α made with the Hubble Space Telescope that were calculated with a radiative transfer model. The FUV-mode stellar calibrated values and HST-based model results agreed with the echelle SWAN calibrated values to within 6% and 4%, respectively. The calibrated IUVS instrument can be used to interpret emissions of atmospheric species at Mars for insights into water evolution at the planet, as well as observed IPH measurements made during cruise for further insights into dynamics of the inner heliosphere.

Published
2017

243. Seasonal Changes In Hydrogen Escape From Mars through Analysis of HST Observations of the Martian Exosphere Near Perihelion

Author

Jean-Loup Bertaux, Jean-Yves Chaufray, Dolon Bhattacharyya, Geronimo L. Villanueva, John Clarke, M. S. Chaffin, Nicholas M. Schneider, Majd Mayyasi, Center for Space Physics [Boston] (CSP), Boston University [Boston] (BU), HELIOS - LATMOS, Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Department of Astronomy [Boston], Laboratory for Atmospheric and Space Physics [Boulder] (LASP), University of Colorado [Boulder], and NASA Goddard Space Flight Center (GSFC)

Subjects
Martian, Physics, 010504 meteorology & atmospheric sciences, HST, Atmosphere, Flux, Astronomy, Mars, Atmosphere of Mars, Mars Exploration Program, 01 natural sciences, Astrobiology, Geophysics, 13. Climate action, Space and Planetary Science, [SDU]Sciences of the Universe [physics], 0103 physical sciences, Solstice, 010303 astronomy & astrophysics, Water vapor, 0105 earth and related environmental sciences, Exosphere, Hydrogen
Abstract

International audience; Hubble Space Telescope (HST) observations of the Martian hydrogen exosphere in Lyman α are presented in this paper for a period when Mars passed perihelion and southern summer solstice in its orbit. The peak intensity in the exospheric Lyman α brightness was recorded after Mars went past its perihelion, slightly after southern summer solstice. The increase in brightness as Mars approached perihelion was found to not be symmetric around the peak, making it impossible to fit the H escape flux trend with a single sinusoidal curve with the peak at perihelion. While the short-term (~30 Earth-days) changes were not directly correlated with changes in the solar Lyman α flux, the long-term (~ 10 Earth-years) trend in the data does show some correlation with solar activity. This suggests that the short-term changes brought about in the exosphere could be due to intrinsic changes occurring within the lower atmosphere. For example, thermospheric heating by dust can alter the cold-trapping mechanism for water vapor resulting in it being present in large quantities at higher altitudes (60-80 km), possibly enhancing the escape flux of H. Therefore, it is important to understand the drivers of atmospheric dynamics in the Martian atmosphere, which produce the yearly-enhanced seasonal changes observed at Mars around periapsis and southern summer solstice in order to accurately determine the total amount of water lost over its history.

Published
2017

244. Birotor dipole for Saturn's inner magnetic field from Cassini observations

Author

Galopeau, Patrick H. M., Cardon, Catherine, HELIOS - LATMOS, Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS), and Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)

Subjects
[SDU] Sciences of the Universe [physics], [SDU]Sciences of the Universe [physics], Physics::Space Physics, Astrophysics::Earth and Planetary Astrophysics
Abstract

International audience; The radio and plasma wave science (RPWS) experiment on board the Cassini spacecraft, orbiting around Saturn since July 2004, revealed the presence of two distinct and variable rotation periods in the Saturnian kilometric radiation (SKR). These two periods were attributed to the northern and southern hemispheres respectively. We suppose that the periodic time modulations present in the SKR are mainly due to the rotation of Saturn's inner magnetic field. The existence of a double period implies that the inner field is not only limited to a simple rotation dipole but displays more complex structures having the same time periodicities than the radio emission. In order to build a model of this complex magnetic field, it is absolutely necessary to know the accurate phases of rotation linked with the two periods. The radio observations from the RPWS experiment allow a continuous and accurate follow-up of these rotation phases, since the SKR emission is permanently observable and produced very close to the planetary surface. A continuous wavelet transform analysis of the intensity of the SKR signal received at 290 kHz between July 2004 and June 2012 was performed in order to calculate in the same time the different periodicities and phases. A dipole model was proposed for Saturn's inner magnetic field: this dipole presents the particularity to have North and South poles rotating around Saturn's axis at two different angular velocities; this dipole is tilted and not centered. 57 Cassini's revolutions, the periapsis of which is less than 5 Saturnian radii, have been selected for this study. For each of these chosen orbits, it is possible to fit with high precision the measurements of the MAG data experiment given by the magnetometers embarked on board Cassini. A nonrotating external magnetic field completes the model. This study suggests that Saturn's inner magnetic field is neither stationary nor fully axisymmetric. These results can be used as a boundary condition for modelling and constraining the planetary dynamo and they can be a starting point for the study of Saturn's inner structure and the comparison with the interior of Jupiter.

Published
2017

245. Recent Advances in Atmospheric, Solar-Terrestrial Physics and Space Weather From a North-South network of scientists [2006-2016] PART A: TUTORIAL

Author

Amory-Mazaudier, Christine, Menvielle, Michel, Curto, J.-J., Huy, Minh Le, POTHIER, Nathalie, Laboratoire de Physique des Plasmas (LPP), Université Paris-Sud - Paris 11 (UP11)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-École polytechnique (X)-Sorbonne Université (SU)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), HELIOS - LATMOS, Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Observatorio del Ebro (OE), Universitat Ramon Llull [Barcelona] (URL)-Consejo Superior de Investigaciones Científicas [Madrid] (CSIC), and Vietnam National University [Hanoï] (VNU)

Subjects
[PHYS.PHYS.PHYS-AO-PH]Physics [physics]/Physics [physics]/Atmospheric and Oceanic Physics [physics.ao-ph], Sun-Earth systems, Magnetosphere, Solar wind, Space Weather, Ionosphere, [PHYS.PHYS.PHYS-AO-PH] Physics [physics]/Physics [physics]/Atmospheric and Oceanic Physics [physics.ao-ph]
Abstract

International audience; This paper reviews scientific advances achieved by a North-South network between 2006 and 2016. These scientific advances concern Solar Terrestrial Physics, Atmospheric Physics and Space Weather. In this part A, we introduce knowledge on the Sun-Earth system. We consider the physical process of the dynamo which is present in the Sun, in the core of the Earth and also in the regions between the Sun and the Earth, the solar wind-magnetosphere and the ionosphere. Equations of plasma physics and Maxwell's equations will be recalled. In the Sun-Earth system there are permanent dynamos (Sun, Earth's core, solar wind - magnetosphere, neutral wind - ionosphere) and non-permanent dynamos that are activated during magnetic storms in the magnetosphere and in the ionosphere. All these dynamos have associated electric currents that affect the variations of the Earth's magnetic field which are easily measurable. That is why a part of the tutorial is also devoted to the magnetic indices which are indicators of the electric currents in the Sun-Earth system. In order to understand some results of the part B, we present some characteristics of the Equatorial region and of the electrodynamics coupling the Auroral and Equatorial regions.

Published
2017

246. MAVEN observations on a hemispheric asymmetry of precipitating ions toward the Martian upper atmosphere according to the upstream solar wind electric field

Author

David Brain, Bruce M. Jakosky, François Leblanc, Yuki Harada, Roberto Livi, Shannon Curry, Jasper Halekas, Gina A. DiBraccio, Takuya Hara, Janet G. Luhmann, Kanako Seki, John E. P. Connerney, James P. McFadden, Space Sciences Laboratory [Berkeley] (SSL), University of California [Berkeley], University of California-University of California, HELIOS - LATMOS, Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Department of Earth and Planetary Science [Tokyo], The University of Tokyo (UTokyo), Laboratory for Atmospheric and Space Physics [Boulder] (LASP), University of Colorado [Boulder], Department of Physics and Astronomy [Iowa City], University of Iowa [Iowa City], NASA Goddard Space Flight Center (GSFC), University of California [Berkeley] (UC Berkeley), University of California (UC)-University of California (UC), Graduate School of Science [Tokyo], and The University of Tokyo (UTokyo)-The University of Tokyo (UTokyo)

Subjects
010504 meteorology & atmospheric sciences, Mars, MAVEN, Hemispheric Asymmetry, Atmospheric sciences, 01 natural sciences, Physics::Geophysics, Atmosphere, Ion Precipitation, Planet, Electric field, 0103 physical sciences, Astrophysics::Solar and Stellar Astrophysics, Interplanetary magnetic field, 010303 astronomy & astrophysics, Physics::Atmospheric and Oceanic Physics, 0105 earth and related environmental sciences, Martian, Physics, Solar Wind Dependence, [SDU.ASTR.SR]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Solar and Stellar Astrophysics [astro-ph.SR], Sputtering, Geophysics, Solar wind, 13. Climate action, Space and Planetary Science, Physics::Space Physics, Magnetopause, Dynamic pressure, Astrophysics::Earth and Planetary Astrophysics
Abstract

International audience; MAVEN observations show that the global spatial distribution of ions precipitating toward the Martian upper atmosphere has a highly asymmetric pattern relative to the upstream solar wind electric field. MAVEN observations indicate that precipitating planetary heavy ion fluxes measured in the downward solar wind electric field (−E) hemisphere are generally larger than those measured in the upward electric field (+E) hemisphere, as expected from modeling. The −E(+E) hemispheres are defined by the direction of solar wind electric field pointing towards (or away from) the planet. On the other hand, such an asymmetric precipitating pattern relative to the solar wind electric field is less clear around the terminator. Strong precipitating fluxes are sometimes found even in the +E field hemisphere under either strong upstream solar wind dynamic pressure or strong interplanetary magnetic field periods. The results imply that those intense precipitating ion fluxes are observed when the gyro radii of pickup ions are estimated to be relatively small compared with the planetary scale. Therefore, the upstream solar wind parameters are important factors in controlling the global spatial pattern and flux of ions precipitating into the Martian upper atmosphere.

Published
2017

247. Remote sensing of the Io torus plasma ribbon using natural radio occultation of the Jovian radio emissions

Author

Sami Sawas, Patrick H. M. Galopeau, Helmut Lammer, Mohammed Y. Boudjada, Space Research Institute of Austrian Academy of Sciences (IWF), Austrian Academy of Sciences (OeAW), HELIOS - LATMOS, Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Institute of communications and wave propagation [Graz], and Graz University of Technology [Graz] (TU Graz)

Subjects
Atmospheric Science, Electron density, [PHYS.ASTR.EP]Physics [physics]/Astrophysics [astro-ph]/Earth and Planetary Astrophysics [astro-ph.EP], Extinction (astronomy), [SDU.ASTR.EP]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Earth and Planetary Astrophysics [astro-ph.EP], Jovian, Jupiter, Earth and Planetary Sciences (miscellaneous), Radio occultation, lcsh:Science, Physics, Waves in plasmas, lcsh:QC801-809, Astronomy, Geology, Astronomy and Astrophysics, lcsh:QC1-999, lcsh:Geophysics. Cosmic physics, 13. Climate action, Space and Planetary Science, Local time, Physics::Space Physics, lcsh:Q, Astrophysics::Earth and Planetary Astrophysics, Longitude, lcsh:Physics
Abstract

We study the Jovian hectometric (HOM) emissions recorded by the RPWS (Radio and Plasma Wave Science) experiment onboard the Cassini spacecraft during its Jupiter flyby. We analyze the attenuation band associated with the intensity extinction of HOM radiation. This phenomenon is interpreted as a refraction effect of the Jovian hectometric emission inside the Io plasma torus. This attenuation band was regularly observed during periods of more than 5 months, from the beginning of October 2000 to the end of March 2001. We estimate for this period the variation of the electron density versus the central meridian longitude (CML). We find a clear local time dependence. Hence the electron density was not higher than 5.0 × 104 cm−3 during 2 months, when the spacecraft approached the planet on the dayside. In the late afternoon and evening sectors, the electron density increases to 1.5 × 105 cm−3 and reach a higher value at some specific occasions. Additionally, we show that ultraviolet and hectometric wavelength observations have common features related to the morphology of the Io plasma torus. The maxima of enhancements/attenuations of UV/HOM observations occur close to the longitudes of the tip of the magnetic dipole in the southern hemisphere (20° CML) and in the northern hemisphere (200° CML), respectively. This is a significant indication about the importance of the Jovian magnetic field as a physical parameter in the coupling process between Jupiter and the Io satellite.

Published
2014

248. A new solar reference spectrum obtained with the SOLAR/SOLSPEC space-based spectro-radiometer

Author

Meftah, Mustapha, Boisée, David, Hauchecorne, Alain, Damé, Luc, Bekki, Slimane, Pereira, Nuno, STRATO - LATMOS, Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Belgian Institute for Space Aeronomy / Institut d'Aéronomie Spatiale de Belgique (BIRA-IASB), HELIOS - LATMOS, and Cardon, Catherine

Subjects
[SDU.ASTR.IM] Sciences of the Universe [physics]/Astrophysics [astro-ph]/Instrumentation and Methods for Astrophysic [astro-ph.IM], [SDU.ASTR.SR]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Solar and Stellar Astrophysics [astro-ph.SR], Physics::Space Physics, [SDU.ASTR.SR] Sciences of the Universe [physics]/Astrophysics [astro-ph]/Solar and Stellar Astrophysics [astro-ph.SR], Astrophysics::Solar and Stellar Astrophysics, Astrophysics::Earth and Planetary Astrophysics, [SDU.ASTR.IM]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Instrumentation and Methods for Astrophysic [astro-ph.IM]
Abstract

International audience; The solar spectrum is a key input for different disciplines such as Solar Physics and Climate Physics. Based on SOLAR/SOLSPEC data, we will present a new solar irradiance spectrum from 165 to 3088 nm. The methodology for obtaining these results will be described. Finally, this new solar reference spectrum will be compared with other solar irradiance reference spectra (ATLAS 3 and WHI 2008).

Published
2016

249. Variability of D and H in the Martian Exosphere

Author

Clarke, John T., Mayyasi, Majd, Bhattacharyya, Dolon, McCord Schneider, Nicholas, Mcclintock, Bill, Deighan, Justin, Stewart, Ian F., Chaufray, Jean-Yves, Chaffin, Michael, Jain, Sonal K., Stiepen, Arnaud, Crismani, Matteo M. J., Holsclaw, Greg, Montmessin, Franck, Jakosky, Bruce Martin, Center for Space Physics [Boston] (CSP), Boston University [Boston] (BU), University of Colorado [Boulder], Laboratory for Atmospheric and Space Physics [Boulder] (LASP), HELIOS - LATMOS, Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), PLANETO - LATMOS, and Cardon, Catherine

Subjects
[PHYS.PHYS.PHYS-AO-PH]Physics [physics]/Physics [physics]/Atmospheric and Oceanic Physics [physics.ao-ph], [SDU.ASTR.IM] Sciences of the Universe [physics]/Astrophysics [astro-ph]/Instrumentation and Methods for Astrophysic [astro-ph.IM], [SDU.ASTR.SR]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Solar and Stellar Astrophysics [astro-ph.SR], [SDU.ASTR.SR] Sciences of the Universe [physics]/Astrophysics [astro-ph]/Solar and Stellar Astrophysics [astro-ph.SR], [SDU.ASTR.EP]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Earth and Planetary Astrophysics [astro-ph.EP], [SDU.ASTR.EP] Sciences of the Universe [physics]/Astrophysics [astro-ph]/Earth and Planetary Astrophysics [astro-ph.EP], [PHYS.PHYS.PHYS-AO-PH] Physics [physics]/Physics [physics]/Atmospheric and Oceanic Physics [physics.ao-ph], [SDU.ASTR.IM]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Instrumentation and Methods for Astrophysic [astro-ph.IM]
Abstract

International audience; The IUVS instrument on MAVEN contains an echelle spectrograph with a novel optical design to enable long-aperture measurements of emission lines in the absence of continuum, intended primarily to measure the H and D Ly α emission lines from the martian upper atmosphere. The main scientific goal of the echelle channel is to measure the H and D Ly α emissions that result from resonant scattering of solar emission and to discover how the H and D densities, temperatures, and escape fluxes vary with location, season, topography, etc. The global D/H ratio of the martian atmosphere is roughly 5 times higher than in the terrestrial atmosphere due to the escape of a large volume of water into space, likely early in the history of Mars. Since H atoms escape faster than D atoms, the D/H ratio increases with time as more water is lost. Earth-based IR observations have indicated large variations in the HDO/H2O ratio in the lower atmosphere from location to location, and possible changes with the atmospheric seasonal cycles [Villanueva et al. 2015]. HST and MEX measurements of the H corona of Mars have shown large (order of magnitude) changes in the H exosphere and escape flux with changing seasons and/or heliospheric distance [Clarke et al. 2014; Chaffin et al. 2014]. A series of observations of D and H with the IUVS echelle channel now show a strong trend in the variation of both emissions, with order of magnitude changes in both species in the upper atmosphere. With the added data expected in Fall 2016, we will be able to determine this trend over a full range of martian solar longitude. These results and a comparison with proposed processes that might lead to the observed changes will be presented.

Published
2016

250. Formation of Accelerated Backstreaming Particles within the Quasi-perpendicular Ion Terrestrial Foreshock: 2D Full-Particle and Test-particles simulations

Author

Savoini, Philippe, Lembège, Bertrand, Laboratoire de Physique des Plasmas (LPP), Université Paris-Saclay-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris-Sud - Paris 11 (UP11)-École polytechnique (X)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL), HELIOS - LATMOS, Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Université Paris-Sud - Paris 11 (UP11)-Observatoire de Paris, and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-École polytechnique (X)-Sorbonne Université (SU)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)

Subjects
[PHYS.PHYS.PHYS-PLASM-PH]Physics [physics]/Physics [physics]/Plasma Physics [physics.plasm-ph], [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph]
Abstract

International audience; Backstreaming ion populations are observed upstream of the Terrestrial bow shock and form the ion foreshock. Two distinct populations have been firmly identified by spacecrafts within the quasi-perpendicular shock region (i.e. for 45°

Published
2016

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