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105 results on '"Hamelin, Michel"'

1. Electrical properties and porosity of the first meter of the nucleus of 67P/Churyumov-Gerasimenko. As constrained by the Permittivity Probe SESAME-PP/Philae/Rosetta

Author

Lethuillier, Anthony, Gall, Alice Le, Hamelin, Michel, Schmidt, Walter, Seidensticker, Klaus J., Grard, Réjean, Ciarletti, Valérie, Caujolle-Bert, Sylvain, Fischer, Hans-Herbert, and Trautner, Roland

Subjects
Astrophysics - Earth and Planetary Astrophysics
Abstract

Context. Comets are primitive objects, remnants of the volatile-rich planetesimals from which the solar system condensed. Knowing their structure and composition is thus crucial for the understanding of our origins. After the successful landing of Philae on the nucleus of 67P/Churyumov-Gerasimenko in November 2014, for the first time, the Rosetta mission provided the opportunity to measure the low frequency electrical properties of a cometary mantle with the permittivity probe SESAME-PP (Surface Electric Sounding and Acoustic Monitoring Experiment - Permittivity Probe). Aims. In this paper, we conduct an in-depth analysis of the data from active measurements collected by SESAME-PP at Abydos, which is the final landing site of Philae, to constrain the porosity and, to a lesser extent, the composition of the surface material down to a depth of about 1 meter. Methods. SESAME-PP observations on the surface are then analyzed by comparison with data acquired during the descent toward the nucleus and with numerical simulations that explore different possible attitudes and environments of Philae at Abydos using a method called the Capacity-Influence Matrix Method. Results. Reasonably assuming that the two receiving electrode channels have not drifted with respect to each other during the ten-year journey of the Rosetta probe to the comet, we constrain the dielectric constant of the first meter below the surface at Abydos to be > 2.45 p/m 0.20, which is consistent with a porosity < 50% if the dust phase is analogous to carbonaceous chondrites and < 75% in the case of less primitive ordinary chondrites. This indicates that the near surface of the nucleus of 67P/Churyumov-Gerasimenko nucleus is more compacted than its interior and suggests that it could consist of a sintered dust-ice layer., Comment: Accepted in Astronomy and Astrophysics,18 pages, 13 figures

Published
2016
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2. A Receptor in Pituitary and Hypothalamus that Functions in Growth Hormone Release

Author

Howard, Andrew D., Feighner, Scott D., Cully, Doris F., Arena, Joseph P., Liberator, Paul A., Rosenblum, Charles I., Hamelin, Michel, Hreniuk, Donna L., Palyha, Oksana C., Hamelin, Michel, Hreniuk, Donna L., Palyha, Oksana C., Anderson, Jennifer, Paress, Philip S., Diaz, Carmen, Chou, Michael, Liu, Ken K., McKee, Karen Kulju, Pong, Sheng-Shung, Chaung, Lee-Yuh, Elbrecht, Alex, Dashkevicz, Mike, Heavens, Robert, Rigby, Mike, Dean, Dennis C., Melillo, David G., Patchett, Arthur A., Nargund, Ravi, Griffin, Patrick R., DeMartino, Julie A., Gupta, Sunil K., Schaeffer, James M., and Smith, Roy G.

Published
1996

6. Measurement of Titan's surface permittivity with the DraGMet/DIEL sensor on Dragonfly

Author

Le Gall, Alice, Chatain, Audrey, Lorenz, Ralph, Hamelin, Michel, Deprez, Grégoire, Osiander, Robert, Berthelier, Jean-Jacques, Hassen-Khodja, Rafik, Lebreton, Jean-Pierre, Joly-Jehenne, Tom, Vettier, Ludovic, Carrasco, Nathalie, PLANETO - 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), Institut Universitaire de France (IUF), Ministère de l'Education nationale, de l’Enseignement supérieur et de la Recherche (M.E.N.E.S.R.), Johns Hopkins University Applied Physics Laboratory [Laurel, MD] (APL), 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), European Space Research and Technology Centre (ESTEC), European Space Agency (ESA), 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, and 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)

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

International audience

Published
2021

8. Measurement of Titan’s surface permittivity with the DraGMet/DIEL sensor on Dragonfly

Author

Le Gall, Alice, primary, Chatain, Audrey, additional, Lorenz, Ralph D., additional, Hamelin, Michel, additional, Deprez, Grégoire, additional, Osiander, Robert, additional, Berthelier, Jean-Jacques, additional, Hassen-Khodja, Rafik, additional, Lebreton, Jean-Pierre, additional, Joly-Jehenne, Tom, additional, Vettier, Ludovic, additional, and Carrasco, Nathalie, additional

Published
2021
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11. Analytic Theory of Titans Schumann Resonance: Constraints on Ionospheric Conductivity and Buried Water Ocean

Author

Beghin, Christian, Randriamboarison, Orelien, Hamelin, Michel, Karkoschka, Erich, Sotin, Christophe, Whitten, Robert C, Berthelier, Jean-Jacques, Grard, Rejean, and Simoes, Fernando

Subjects
Space Sciences (General)
Abstract

This study presents an approximate model for the atypical Schumann resonance in Titan's atmosphere that accounts for the observations of electromagnetic waves and the measurements of atmospheric conductivity performed with the Huygens Atmospheric Structure and Permittivity, Wave and Altimetry (HASI-PWA) instrumentation during the descent of the Huygens Probe through Titan's atmosphere in January 2005. After many years of thorough analyses of the collected data, several arguments enable us to claim that the Extremely Low Frequency (ELF) wave observed at around 36 Hz displays all the characteristics of the second harmonic of a Schumann resonance. On Earth, this phenomenon is well known to be triggered by lightning activity. Given the lack of evidence of any thunderstorm activity on Titan, we proposed in early works a model based on an alternative powering mechanism involving the electric current sheets induced in Titan's ionosphere by the Saturn's magnetospheric plasma flow. The present study is a further step in improving the initial model and corroborating our preliminary assessments. We first develop an analytic theory of the guided modes that appear to be the most suitable for sustaining Schumann resonances in Titan's atmosphere. We then introduce the characteristics of the Huygens electric field measurements in the equations, in order to constrain the physical parameters of the resonating cavity. The latter is assumed to be made of different structures distributed between an upper boundary, presumably made of a succession of thin ionized layers of stratospheric aerosols spread up to 150 km and a lower quasi-perfect conductive surface hidden beneath the non-conductive ground. The inner reflecting boundary is proposed to be a buried water-ammonia ocean lying at a likely depth of 55-80 km below a dielectric icy crust. Such estimate is found to comply with models suggesting that the internal heat could be transferred upwards by thermal conduction of the crust, while convective processes cannot be ruled out.

Published
2013
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12. Using Schumann Resonance Measurements for Constraining the Water Abundance on the Giant Planets - Implications for the Solar System Formation

Author

Simoes, Fernando, Pfaff, Robert, Hamelin, Michel, Klenzing, Jeffrey, Freudenreich, Henry, Beghin, Christian, Berthelier, Jean-Jacques, Bromund, Kenneth, Grard, Rejean, Lebreton, Jean-Pierre, Martin, Steven, Rowland, Douglas, Sentman, Davis, Takahashi, Yukihiro, and Yair, Yoav

Subjects
Space Sciences (General)
Abstract

The formation and evolution of the Solar System is closely related to the abundance of volatiles, namely water, ammonia, and methane in the protoplanetary disk. Accurate measurement of volatiles in the Solar System is therefore important to understand not only the nebular hypothesis and origin of life but also planetary cosmogony as a whole. In this work, we propose a new, remote sensing technique to infer the outer planets water content by measuring Tremendously and Extremely Low Frequency (TLF-ELF) electromagnetic wave characteristics (Schumann resonances) excited by lightning in their gaseous envelopes. Schumann resonance detection can be potentially used for constraining the uncertainty of volatiles of the giant planets, mainly Uranus and Neptune, because such TLF-ELF wave signatures are closely related to the electric conductivity profile and water content.

Published
2012

13. Comment on 'An Analysis of VLF Electric Field Spectra Measured in Titan's Atmosphere by The Huygens Probe' By J. A. Morente et al.

Author

Grard, Rejean, Berthelin, Stephanie, Beghin, Christian, Hamelin, Michel, Berthelier, Jean-Jacques, Lopez-Moreno, Jose J, and Simoes, Fernando

Subjects
Lunar And Planetary Science And Exploration
Abstract

Morente et al. have recently revisited the VLF electric field measurements made with the Permittivity, Wave and Altimetry (PWA) instrument during the descent of the Huygens Probe through the atmosphere of Titan. They assert that they have identified several harmonics of the transverse resonance mode of the surface?]ionosphere cavity, which would prove the existence of an electrical activity in the atmosphere of the largest satellite of Saturn. We refute this finding on the basis that it results from an artifact due to an improper analysis of the data set. [2] The investigators of the Permittivity, Wave and Altimetry (PWA) experiment on the Huygens Probe have reported the extremely low frequency (ELF) and very low frequency (VLF) electric signals recorded during the descent through the atmosphere of Titan. The PWA data are archived in the Planetary Science Archive (PSA) of ESA, and an extensive description of the instrument is at the disposal of the scientific community. Morente and his coworkers have revisited this data set and reported the results of their investigations in two papers. In a first paper, they claim that they have detected in the ELF range (0.100 Hz) several harmonics of a global resonance allegedly generated by lightning activity in the spherical cavity guide formed by the surface of Titan and the inner boundary of the ionosphere, a phenomenon similar to the Schumann resonance observed at EartH In the second paper dedicated to the VLF electric signal recorded by PWA, in the range 0.10 kHz, they argue that they can also bring out the transverse resonance and its harmonics, a more local phenomenon that develops around the excitation source and whose frequency is controlled by the separation between Titan?fs surface and the inner ionospheric boundary. [3] The PWA investigators have analyzed the narrowband ELF signal at about 36 Hz effectively observed during the entire descent. They have not endorsed, however, the alternative approach of Morente et al. that discloses additional ELF narrow-band signals and numerous related harmonics. Hamelin et al. and Beghin et al. have questioned the work of Morente and his coworkers and demonstrated unambiguously that their findings are mere artifacts entirely due to a faulty procedure. Morente et al. refuted this critical analysis of their ELF paper in a rebuttal. The present comment draws a parallelism between the ELF and VLF papers and demonstrates that the VLF signal carries no evidence whatever of any transverse resonance. The analyses of the ELF and VLF signals by Morente and his coworkers are flawed, and their conclusions are shown here to be invalid. A more comprehensive and thorough assessment of the numerical approaches proposed by Morente et al. is given by Berthelin et al..

Published
2011
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15. Expression of the UNC-5 guidance receptor in the touch neurons of C. elegans steers their axons dorsally

Author

Hamelin, Michel, Youwen, Zhou, Ming-Wan, Su, Scott, Ian M., and Culotti, Joseph G.

Subjects
Neurobiology -- Research, Neurons -- Growth, Caenorhabditis elegans -- Physiological aspects, Environmental issues, Science and technology, Zoology and wildlife conservation
Abstract

Ectopic expression of the UNC-5 guidance receptor in Caenorhabditis elegans makes touch receptor neurons extend pioneer axons dorsally, rather than longitudinally or ventrally as is normal. UNC-5, encoded by the unc-5 gene, seems to reorient the touch cell growth cones through its normal guidance mechanisms. Pioneer growth cones that normally migrate dorsally on the epidermis may differ from those migrating ventrally or longitudinally only in having different surface receptors.

Published
1993

18. Electrical properties of the first meters of 67P/Churyumov-Gerasimenko’s nucleus as constrained by PP-SESAME/Philae/Rosetta

Author

Le Gall, Alice, Lethuillier, Anthony, Hamelin, Michel, Schmidt, Walter, Grard, Rejean, Ciarletti, V., Seidensticker, Klaus J., Caujolle-Bert, Sylvain, Fischer, Hans-Herbert, 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), Finnish Meteorological Institute (FMI), Research and Scientific Support Department, ESTEC (RSSD), European Space Research and Technology Centre (ESTEC), European Space Agency (ESA)-European Space Agency (ESA), Deutsches Zentrum für Luft- und Raumfahrt (DLR), 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), DLR Microgravity User Support Center (MUSC), and Agence Spatiale Européenne = European Space Agency (ESA)-Agence Spatiale Européenne = European Space Agency (ESA)

Subjects
Rosetta Philae SESAME PP, Institut für Planetenforschung, [SDU.ASTR.EP]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Earth and Planetary Astrophysics [astro-ph.EP], Nutzerzentrum für Weltraumexperimente (MUSC), [SDU.ASTR.IM]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Instrumentation and Methods for Astrophysic [astro-ph.IM]
Abstract

International audience; On November 12, 2014, the Philae module landed on the surface of the nucleus of 67P/Churyumov-Gerasimenko. Among the instruments on-board Philae, the Permittivity Probe experiment (hereafter PP-SESAME), which is part of the SESAME (Surface Electric Sounding and Acoustic Monitoring Experiment) package, operated both during descent and on the surface. The primary scientific objective of this experiment is to measure the low frequency (10 Hz-10 kHz) complex permittivity i.e. the dielectric constant and electrical conductivity, of the first meters of the cometary nucleus. Doing so, it aims at providing insights into the composition of the mantle and in particular into the water content and porosity of the first meters below the surface.In this paper, we will present the data acquired at the final landing site of Philae known as Abydos and the approach we have developed to analyze them. We emphasize that, because the configuration of operation of PP-SESAME was far from nominal, we had to adapt our analysis method in order to account for all available constraints on Philae attitude and environment at Abydos. We also had to do without the in-flight calibration performed during the descent phase but unfortunately perturbed by the concurrent operations of the bistatic radar CONSERT.We find that the first meters of the nucleus at Abydos are made of a likely pure dielectric material (i.e. with a null conductivity) which dielectric constant is larger than 2.3. This lower bound of the dielectric constant is significantly higher than the value of 1.27 inferred from the propagation time of the CONSERT signals that propagated through the smaller lobe of the comet in the vicinity of Abydos reaching depths of a few hundreds of meters. Thus, while PP-SESAME measurements put no constraint on the dust-to-ice ratio, they strongly suggest that the first meters of the nucleus are significantly more compacted (with a porosity below 50%) than its interior as sensed by CONSERT (found to have a porosity in of 75 to 85%, consistent with the low density of the nucleus). In light of other Philae and Rosetta observations, we will discuss the implications of these findings in terms of formation and evolution of cometary mantles.

Published
2016

19. In-situ Properties of Comet 67P/Churyumov-Gerasimenko measured with SESAME

Author

Seidensticker, Klaus J., Fischer, Hans-Herbert, Krüger, Harald, Schmidt, Walter, Apathy, Istvan, Arnold, Walter, Flandes, Alberto, Hamelin, Michel, Hirn, Attila, Knapmeyer, Martin, Le Gall, Alice, Möhlmann, D., Thiel, Klaus, Faber, Claudia, Lethuillier, Anthony, Deutsches Zentrum für Luft- und Raumfahrt (DLR), DLR Microgravity User Support Center (MUSC), Max Planck Institute for Solar System Research (MPS), Max-Planck-Gesellschaft, Finnish Meteorological Institute (FMI), MTA Centre for Energy Research, I. Physikalisches Institut [Göttingen], Georg-August-University [Göttingen], Universität des Saarlandes [Saarbrücken], Instituto de Geofisica [Mexico], Universidad Nacional Autónoma de México (UNAM), 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), ESTER - LATMOS, DLR Institut für Planetenforschung, Deutsches Zentrum für Luft- und Raumfahrt [Berlin] (DLR), Universität zu Köln, Cardon, Catherine, Max-Planck-Institut für Sonnensystemforschung = Max Planck Institute for Solar System Research (MPS), Georg-August-University = Georg-August-Universität Göttingen, Universidad Nacional Autónoma de México = National Autonomous University of Mexico (UNAM), and Universität zu Köln = University of Cologne

Subjects
[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], Rosetta Philae SESAME
Abstract

International audience; The SESAME experiment (Surface Electric Sounding and Acoustic Monitoring Experiment) is part of the lander Philae of the ESA Rosetta mission that landed on the nucleus of comet 67P/Churyumov-Gerasimenko on 12 November 2014. SESAME is a suite of the three instruments CASSE, DIM and PP that use different measurement techniques in order to determine physical properties of the surface and the activity of 67P. SESAME was operated successfully during the descent until the end of the First Science Sequence (FSS). The Comet Acoustic Surface Sounding Experiment (CASSE) can record and generate acoustic vibrations with two kinds of sensors in the range from 50 Hz to 10 kHz. It was operated during the descent and measured completely Philae's first touchdown at Agilkia at 15:34:04 UTC with three triaxial accelerometers mounted in Philae's feet. These data, which are influenced by the properties of Philae's landing gear and by the complex surface layer at Agilkia with a regolith ranging from dust to boulders, describe the sequence of Philae's surface contacts. At the final landing site Abydos, CASSE recorded many signals generated by the hammering of the Philae experiment MUPUS-Pen, in order to determine sound velocities of the cometary surface layer and related elastic properties. Finally, CASSE conducted sounding measurements from foot to foot. The Dust Impact Monitor (DIM) used three piezoelectric sensor plates orthogonally mounted on a cube to detect impacts of sub-millimeter and millimeter-sized ice and dust particles that are emitted from the cometary surface. DIM measurements during the 7 h descent to the cometary surface were hampered by the fact that none of the sensor plates pointed to the cometary surface. Nevertheless, one millimeter- sized particle was detected at an altitude of 2.4 km. Comparison with laboratory data showed that the particle properties are compatible with a porous grain having a bulk density of approximately 250 kg m**-3. At Abydos, DIM recorded no particle impacts, which may be due either to low cometary activity at this place or shading by obstacles close to Philae or both. The SESAME Permittivity Probe (PP) is a combined quadrupole permittivity detector and plasma wave sensor. The unplanned landing in Abydos required many modifications to the FSS operation plan. Thus, PP could study the surface layer with only a three-electrode configuration reducing the resolution significantly. Nevertheless, PP's data constrain the relative permittivity of the surface material to about 2.5 at a surface temperature of about -160 °C for the position of Philae's foot –Y, which was in permanent shadow. This result suggests that the first meters of the surface of Abydos are more compact and/or richer in dust than its interior as probed by the orbiter/lander experiment CONSERT. Additionally, PP detected weak plasma wave activities at Abydos two hours after local sunset. By combining data from different FSS operation periods, we were able to determine temperature profiles of the CASSE sensors in each Philae foot over 9.2 h of a 12.4 h comet day. With proper modeling, these data could give the surface temperature variation at Abydos during FSS.

Published
2016

20. Electrical Properties and Porosity of the First Meter of the Nucleus of 67P/Churyumov-Gerasimenko

Author

Lethuillier, Anthony, Le Gall, Alice, Hamelin, Michel, Schmidt, Walter, Seidensticker, Klaus J., Grard, R., Ciarletti, V., Caujolle-Bert, Sylvain, Fischer, Hans-Herbert, and Trautner, Roland

Subjects
Institut für Planetenforschung, Rosetta Philae SESAME PP Comets: individual: 67P/Churyumov-Gerasimenko Methods: numerical Methods: data analysis Space vehicles: instruments Planets and satellites: surfaces, Nutzerzentrum für Weltraumexperimente (MUSC)
Abstract

Context. Comets are primitive objects, remnants of the volatile-rich planetesimals from which the solar system condensed. Knowing their structure and composition is thus crucial for the understanding of our origins. After the successful landing of Philae on the nucleus of 67P/Churyumov-Gerasimenko in November 2014, for the first time, the Rosetta mission provided the opportunity to measure the low frequency electrical properties of a cometary mantle with the permittivity probe SESAME-PP (Surface Electric Sounding and Acoustic Monitoring Experiment−Permittivity Probe). Aims. In this paper, we conduct an in-depth analysis of the data from active measurements collected by SESAME-PP at Abydos, which is the final landing site of Philae, to constrain the porosity and, to a lesser extent, the composition of the surface material down to a depth of about 1 m. Methods. SESAME-PP observations on the surface are then analyzed by comparison with data acquired during the descent toward the nucleus and with numerical simulations that explore different possible attitudes and environments of Philae at Abydos using a method called the Capacity-Influence Matrix Method. Results. Reasonably assuming that the two receiving electrode channels have not drifted with respect to each other during the ten-year journey of the Rosetta probe to the comet, we constrain the dielectric constant of the first meter below the surface at Abydos to be >2.45 ± 0.20, which is consistent with a porosity

Published
2016

21. Mapping of the cometary plasma density around comet CG/67P at perihelion

Author

Henri, Pierre, Eriksson, Anders, Edberg, Niklas, Béghin, Christian, Décréau, Pierrette, Grard, Réjean, Hamelin, Michel, Johansson, Erik, Lebreton, Jean-Pierre, Mazelle, Christian, Odelstad, Elias, Randriamboarison, Orélien, Schmidt, Walter, Wattieaux, Gaëtan, Winterhalter, Daniel, Vallières, Xavier, Vigren, Erik, Glassmeier, Karl-Heinz, Goetz, Charlotte, Koenders, Christoph, Richter, Ingo, Volwerk, Martin, Burch, James, Broiles, Thomas, Golstein, Ray, Mandt, Kathleen, Mokashi, Prachet, Nilsson, Hans, Sternberg Wieser, Gabriella, Carr, Chris, Cupido, Emanuele, Galand, Marina, Matteini, Lorenzo, Nemeth, Zoltan, Szego, Karoly, Vallat, C., Schwartz, Steven, 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), Swedish Institute of Space Physics [Uppsala] (IRF), Research and Scientific Support Department, ESTEC (RSSD), European Space Research and Technology Centre (ESTEC), European Space Agency (ESA)-European Space Agency (ESA), 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), Centre d'étude spatiale des rayonnements (CESR), 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)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-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, Finnish Meteorological Institute (FMI), Plasmas Réactifs Hors Equilibre (LAPLACE-PRHE), LAboratoire PLasma et Conversion d'Energie (LAPLACE), Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université Fédérale Toulouse Midi-Pyrénées-Université Toulouse III - Paul Sabatier (UT3), Jet Propulsion Laboratory (JPL), California Institute of Technology (CALTECH)-NASA, Technische Universität Braunschweig = Technical University of Braunschweig [Braunschweig], Austrian Academy of Sciences (OeAW), Southwest Research Institute [San Antonio] (SwRI), Blackett Laboratory, Imperial College London, Wigner Research Centre for Physics [Budapest], Hungarian Academy of Sciences (MTA), European Space Astronomy Centre (ESAC), European Space Agency (ESA), Agence Spatiale Européenne = European Space Agency (ESA)-Agence Spatiale Européenne = European Space Agency (ESA), 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), Université de Toulouse (UT)-Université de Toulouse (UT)-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université de Toulouse (UT)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT), NASA-California Institute of Technology (CALTECH), and Agence Spatiale Européenne = European Space Agency (ESA)

Subjects
[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.IM]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Instrumentation and Methods for Astrophysic [astro-ph.IM]
Abstract

International audience; In August 2015, comet 67P/Churyumov-Gerasimenko, target of the ESA’s Rosetta mission, reached its perihelion at 1.3 AU from the Sun. The Rosetta Plasma Consortium (RPC) onboard the Rosetta spacecraft offers a unique opportunity to analyze the plasma environment during this period. Combining observations from the Mutual Impedance probe (RPC-MIP) and the Langmuir probes (RPC-LAP), we estimate the cometary plasma density. We will present its spatial distribution around the comet when close to perihelion. Combined Mutual impedance and Langmuir probes density measurements are also compared to the density derived from particle measurements (RPC-ICA and RPC-IES). In addition, we will focus on localised, strong variations of the cometary plasma density over short timescales (~ minutes to seconds) observed during this period. These strong plasma density enhancements are interpreted taken into account the electron energy spectrum measured by the Ion and Electron Spectrometer (RPC-IES). Possible correlations of these plasma enhancements with variations in the magnetic field direction measured from the Magnetometer (RPC-MAG) will be discussed.

Published
2015

22. Findings from the PP-SESAME experiment on board the Philae/ROSETTA lander on the surface of comet 67P

Author

Lethuillier, Anthony, Le Gall, Alice, Hamelin, Michel, Ciarletti, Valérie, Caujolle-Bert, Sylvain, Schmidt, W., Grard, R., Fischer, H., Seidensticker, K., 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), 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), Finnish Meteorological Institute (FMI), Research and Scientific Support Department, ESTEC (RSSD), European Space Research and Technology Centre (ESTEC), European Space Agency (ESA)-European Space Agency (ESA), German Aerospace Center (DLR), and Agence Spatiale Européenne = European Space Agency (ESA)-Agence Spatiale Européenne = European Space Agency (ESA)

Subjects
[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]
Abstract

International audience; The Permittivity Probe (PP-SESAME [1]) on-board the Philae Lander of the ROSETTA mission was designed to constrain the complex permittivity of the first 2 meters of the nucleus of comet 67P/Churyumov-Gerasimenko and to monitor its variations with time. Doing so, it is meant to provide unique insight into the composition (and activity if data could have been acquired longer) of the comet. In this paper, we present the analysis of the PP-SESAME measurements acquired during the first science sequence, on November 13, 2014, on the surface of the comet.

Published
2015

23. Mutual Impedance Probes on board Rosetta, Bepi-Colombo and JUICE

Author

Henri, Pierre, Lebreton, Jean-Pierre, Rauch, Jean-Louis, Béghin, Christian, Décréau, Pierrette, Eriksson, Anders, Grard, Réjean, Hamelin, Michel, Mazelle, Christian, Randriamboarison, Orélien, Schmidt, Walter, Trotignon, Jean-Gabriel, Wattieaux, Gaëtan, Winterhalter, Daniel, Aouad, Youcef, Colin, Fabrice, Lagoutte, Dominique, Duff, Olivier Le, Vallières, Xavier, 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), Swedish Institute of Space Physics [Uppsala] (IRF), Research and Scientific Support Department, ESTEC (RSSD), European Space Research and Technology Centre (ESTEC), European Space Agency (ESA)-European Space Agency (ESA), 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), 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), Finnish Meteorological Institute (FMI), Plasmas Réactifs Hors Equilibre (LAPLACE-PRHE), LAboratoire PLasma et Conversion d'Energie (LAPLACE), Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université Fédérale Toulouse Midi-Pyrénées-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées, Jet Propulsion Laboratory (JPL), California Institute of Technology (CALTECH)-NASA, Laboratoire de physique et chimie de l'environnement (LPCE), Institut national des sciences de l'Univers (INSU - CNRS)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS), Agence Spatiale Européenne = European Space Agency (ESA), 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), Université de Toulouse (UT), NASA-California Institute of Technology (CALTECH), Agence Spatiale Européenne = European Space Agency (ESA)-Agence Spatiale Européenne = European Space Agency (ESA), Université de Toulouse (UT)-Université de Toulouse (UT)-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), and Université de Toulouse (UT)-Université Toulouse III - Paul Sabatier (UT3)

Subjects
Plasma, Mutual Impedance Probe, [SDU]Sciences of the Universe [physics], BepiColombo, Rosetta, [SDU.ASTR.EP]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Earth and Planetary Astrophysics [astro-ph.EP], Instrument, radio frequency probe, JUICE, [SDU.ASTR.IM]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Instrumentation and Methods for Astrophysic [astro-ph.IM]
Abstract

International audience; The mutual impedance probe is an active radio frequency probe, designed to measure in situ the bulk plasma properties. An ideal configuration consists of both a transmitting and a receiving dipole, whose baseline is at least a few Debye Lengths. Due to various accommodation constraints on the spacecraft, the transmitter may only be a monopole. In that case, the image of the transmitter charge is distributed over the whole spacecraft surface. The operating principle consists in injecting a frequency-variable current through the transmitter, in a frequency range that encompasses the plasma frequency (or upper hybrid frequency in a magnetised plasma), and measuring the induced voltage at the receiver. Assuming a transmitted current I(f) of constant amplitude that induces a potential difference V(f) at the receiver dipole, the mutual impedance probe provides the coupling complex impedance Z(f) = V(f)/I(f) between the transmitter and the receiver as a function of frequency. The impedance depends on the plasma properties, in particular the bulk density and temperature (in case of a Maxwellian distribution) of the electron population. The measurement principle is illustrated with in situ observations from the Mutual Impedance Probe (RPC-MIP), one of the five sensors of the Rosetta Plasma Consortium (RPC) on the ESA Rosetta mission. RPC-MIP has been providing regular measurements of the comet plasma environment since early August 2014 when Rosetta was within 100 km from the nucleus of its target comet 67P/Churyumov-Gerasimenko. RPC-MIP operates in the frequency range from 7 kHz to 3.5 MHz that allows covering the plasma density range expected during the mission from solar wind to deep coma densities. RPC-MIP operates in two geometrical configurations. In the baseline configuration, the transmitter and receiver dipoles are aligned on a 1m-beam. The transmitter-receiver distance, of the order of 50 cm, allows probing plasmas with Debye lengths up to 20-25 cm. For longer Debye lengths, MIP uses as the transmitter, one of the two Langmuir Probes of the RPC-LAP instrument located at about 4 m from the MIP receiving dipole, which allows probing plasma with Debye lengths up to about 2 m. Based on the same principle the Permittivity Probe (SESAME-PP), attached to the Rosetta Lander Philae, measures the electrical properties of the cometary surface material in the frequency range 20 Hz to 10 kHz. Regarding future space missions, AM2P (Active Measurement of Mercury's Plasma) is the mutual impedance experiment of the PWI (Plasma Wave Investigation) consortium, on board the MMO spacecraft of the Bepi-Colombo ESA-JAXA mission scheduled for a mid-2016 launch and arrival at Mercury in 2024. MIME (Mutual Impedance MEasurements) is the mutual impedance experiment of the RPWI (Radio and Plasma Waves Investigation) on board the ESA mission JUICE, scheduled for launch in 2022 and arrival at Jupiter in 2030.

Published
2015

24. Observations performed by the SESAME/Permittivity Probe during the descent and after the landing of Philae upon the nucleus of Comet Churyumov–Gerasimenko

Author

Schmidt, Walter, Le Gall, Alice, Hamelin, Michel, Caujolle-Bert, Sylvain, Lethuillier, Anthony, Ciarletti, Valérie, Grard, Réjean, Finnish Meteorological Institute (FMI), 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), 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), Research and Scientific Support Department, ESTEC (RSSD), European Space Research and Technology Centre (ESTEC), Agence Spatiale Européenne = European Space Agency (ESA)-Agence Spatiale Européenne = European Space Agency (ESA), and European Space Agency (ESA)-European Space Agency (ESA)

Subjects
[SDU.ASTR.EP]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Earth and Planetary Astrophysics [astro-ph.EP]
Abstract

International audience; The Permittivity Probe (PP), a component of the SESAME instrument on board Rosetta's Lander Philae, was operated prior to the separation of Philae from Rosetta, during the descent and at the location of the final landing site. The working principle of PP consists in measuring, with a receiving dipole, the voltage induced in the medium by a current of known phase and amplitude injected by a transmitting antenna. The primary objective of PP is to analyse the electrical properties of the comet surface material down to a depth of about 2 m, and to record their variations with temperature, solar illumination and heliocentric distance. These observations are particularly sensitive to the concentration of water ice at the landing site. The second objective of the instrument is to monitor the spectrum of the electromagnetic and electrostatic waves generated by the interaction between the comet and the solar wind at frequencies of up to 20 kHz. The measurements performed during the descent were mainly devoted to the calibration of the instrument in its nominal configuration, with deployed landing gear and away from the Rosetta spacecraft influence, in an environment of known permittivity, either a vacuum or a plasma whose density and temperature would have been derived from the LAP and MIP data. This approach is unfortunately invalidated owing to the fact the PP receiver was most of the time saturated by the operation of the CONSERT radar during the descent, an interference which seemed to have been minimized during in-flight interference tests, but which was significantly stronger after separation of Philae from Rosetta. Nevertheless, it was possible to recover some information about the instrument's transmitter and receiver performances then used during the analysis of the data measured on the cometary surface.

Published
2015

25. Findings and questions from ten years of analysis of the PWA-HASI data collected onboard the HUYGENS probe in the atmosphere and on the surface of Titan

Author

Hamelin, Michel, Lethuillier, Anthony, Le Gall, Alice, Grard, R., Ciarletti, Valérie, Béghin, Christian, Schwingenschuh, Konrad, Lorenz, R.D., López-Moreno, J.J., Jernej, I., Brown, V., Ferri, F., Godard, R., Wattieaux, Gaëtan, 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), Research and Scientific Support Department, ESTEC (RSSD), European Space Research and Technology Centre (ESTEC), European Space Agency (ESA)-European Space Agency (ESA), 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), Space Research Institute of Austrian Academy of Sciences (IWF), Austrian Academy of Sciences (OeAW), Johns Hopkins University (JHU), Instituto de Astrofísica de Andalucía (IAA), Consejo Superior de Investigaciones Científicas [Madrid] (CSIC), Centro di Ateneo di Studi e Attività Spaziali 'Giuseppe Colombo' (CISAS), Universita degli Studi di Padova, Department of Mathematics and Computer Science [Kingston], Royal Military College of Canada, Plasmas Réactifs Hors Equilibre (LAPLACE-PRHE), LAboratoire PLasma et Conversion d'Energie (LAPLACE), Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université Fédérale Toulouse Midi-Pyrénées-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées, Agence Spatiale Européenne = European Space Agency (ESA)-Agence Spatiale Européenne = European Space Agency (ESA), Università degli Studi di Padova = University of Padua (Unipd), Université de Toulouse (UT)-Université de Toulouse (UT)-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université de Toulouse (UT)-Université Toulouse III - Paul Sabatier (UT3), and Université de Toulouse (UT)

Subjects
[SDU.ASTR.EP]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Earth and Planetary Astrophysics [astro-ph.EP], ComputingMilieux_MISCELLANEOUS
Abstract

International audience

Published
2015

26. Noteworthy Returns from Titan’s Schumann Resonance revealed by HASI-PWA Huygens Instrument

Author

Béghin, Christian, Hamelin, Michel, Grard, R., Sotin, C., Schwingenschuh, Konrad, López-­‐Moreno, J.J., Whitten, R.C., 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), 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), Research and Scientific Support Department, ESTEC (RSSD), European Space Research and Technology Centre (ESTEC), Agence Spatiale Européenne = European Space Agency (ESA)-Agence Spatiale Européenne = European Space Agency (ESA), Jet Propulsion Laboratory (JPL), NASA-California Institute of Technology (CALTECH), Space Research Institute of Austrian Academy of Sciences (IWF), Austrian Academy of Sciences (OeAW), Instituto de Astrofísica de Andalucía (IAA), Consejo Superior de Investigaciones Científicas [Madrid] (CSIC), SETI Institute, European Space Agency (ESA)-European Space Agency (ESA), and California Institute of Technology (CALTECH)-NASA

Subjects
[SDU.ASTR.EP]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Earth and Planetary Astrophysics [astro-ph.EP]
Abstract

International audience; After the confirmed absence of any detectable lightning activity in Titan’s atmosphere, the only conceivable generation mechanism of Titan’s Schumann Resonances comes from sets of ionopause current sheets induced by Saturn’s magnetosphere interaction.A day-­‐light/ram-­‐side atmospheric profile model applicable to Huygens descent is constrained by the Modal Equations of the observed 2nd SR Eigenmode.The same method allows to constrain the thickness and the average permittivity of the icy crust, and to reveal the presence of a liquid water ocean buried from 60 to 80 km below the surface.The model accounts for the observation of the 2nd mode only, because the meridional orientation of Saturn’s magnetic field at the Titan’s interface during bi-­‐polar condiLons.The strength of secondary magnetic field induced in the atmosphere by the current sheets is decreasing from a few nT at 1000 km down to about 0.3 nT at 200 km altitude, extending far beneath the surface and the buried ocean.The fleeting remanence of this magnetic field after Titan would have left the Saturn’s magnetosphere could explain the existence of a “fossil” field observed in such a case

Published
2015

27. First Rosetta Observations of the Cometary Plasma at Churyumov–Gerasimenko with the Mutual Impedance Probe (RPC-MIP)

Author

Henri, Pierre, Lebreton, Jean-Pierre, Béghin, Christian, Décréau, Pierrette, Eriksson, Anders, Geiswiller, Johann, Grard, Rejean, Hamelin, Michel, Mazelle, Christian, Randriamboarison, Orélien, Schmidt, Walter, Trotignon, Jean-Gabriel, Wattieaux, Gaëtan, Winterhalter, Daniel, Aouad, Youcef, Lagoutte, Dominique, Vallières, Xavier, Carr, Chris, Cupido, Emanuele, 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)-Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Centre National d’Études Spatiales [Paris] (CNES), Swedish Institute of Space Physics [Uppsala] (IRF), Direction générale de l'Armement (DGA), European Space Research and Technology Centre (ESTEC), European Space Agency (ESA), IMPEC - 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 Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Observatoire Midi-Pyrénées (OMP), Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS), Finnish Meteorological Institute (FMI), LAboratoire PLasma et Conversion d'Energie (LAPLACE), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université Fédérale Toulouse Midi-Pyrénées, Jet Propulsion Laboratory (JPL), California Institute of Technology (CALTECH)-NASA, Blackett Laboratory, Imperial College London, 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), PLANETO - LATMOS, Institut national des sciences de l'Univers (INSU - CNRS)-Université Toulouse III - Paul Sabatier (UT3), 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), Plasmas Réactifs Hors Equilibre (LAPLACE-PRHE), Université Fédérale Toulouse Midi-Pyrénées-Université Toulouse III - Paul Sabatier (UT3), Agence Spatiale Européenne = European Space Agency (ESA), 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), Université de Toulouse (UT)-Université de Toulouse (UT)-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université de Toulouse (UT)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT), and NASA-California Institute of Technology (CALTECH)

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

International audience; The ROSETTA spacecraft arrived in the vicinity of the comet in early August. As part of the Rosetta Plasma Consortium (RPC), the Mutual Impedance Probe (RPC-MIP) is designed to measure the bulk plasma properties in the comet environment. MIP is an active RF probe. It consists of two transmitters, which can operate separately as a monopole or coupled as a transmitting dipole, and a receiving dipole. The operating range of MIP is 7 kHz to 3.5 MHz that allows covering the plasma density range expected during the mission from solar wind to deep coma densities. The baseline distance between the transmitter and the receiver is 40-60 cm, which allows probing plasmas with Debye lengths up to 20-25 cm. For longer Debye lengths, MIP uses one of the two Langmuir Probes of the RPC-LAP instrument located at about 4 m from the MIP receiving dipole, which allows probing plasma with Debye lengths up to about 2 m. The MIP receiving dipole (baseline 1 m) can also be used in a passive mode to measure the electrical activity in the comet environment in the same frequency range. In the active mode, MIP measures the coupling complex impedance between the transmitting monopole (or dipole) and the receiving dipole. To model the frequency response of MIP, a surface charge distribution method is used that takes into account the charge distribution induced on the spacecraft structures by the transmitter. The spacecraft surface is approximated by discrete elements smaller in size than the plasma Debye length. In our model, it is assumed that each spacecraft elementary surface carries a uniform charge distribution. The electric field measured by the receiver is the sum of the contributions from the transmitter itself and of all the elementary surfaces that represent the spacecraft. The frequency of the transmitted current is varied in frequency steps. Assuming a transmitted current I(f) of constant amplitude, the potential difference V(f) between the two receivers provides the mutual impedance Z(f)=V(f)/I(f) of the instrument as a function of frequency. The first observations in active mode, as well as the background electric wave activity in the vicinity of the comet 67P/Churyumov-Gerasimenko are presented. Preliminary inferred plasma parameters, such as bulk electron density and temperature, are derived by using the model for the MIP frequency response.

Published
2014

28. Titan Ground Complex Permittivity at the HUYGENS Landing Site; the PWA-HASI and Other Instruments Data Revisited

Author

Hamelin, Michel, Lethuillier, Anthony, Le Gall, Alice, Grard, Rejean, Ciarletti, Valérie, Béghin, Christian, Schwingenschuh, Konrad, Lorenz, Ralph, Lopez-Moreno, Jose, Jemej, Imgard, Brown, Vic, Ferri, Francesca, 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), Université de Technologie de Troyes (UTT), European Space Research and Technology Centre (ESTEC), European Space Agency (ESA), 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), Space Research Institute of Austrian Academy of Sciences (IWF), Austrian Academy of Sciences (OeAW), Johns Hopkins University (JHU), Instituto de Astrofísica de Andalucía (IAA), Consejo Superior de Investigaciones Científicas [Madrid] (CSIC), Universita degli Studi di Padova, Agence Spatiale Européenne = European Space Agency (ESA), and Università degli Studi di Padova = University of Padua (Unipd)

Subjects
[SDU.ASTR.EP]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Earth and Planetary Astrophysics [astro-ph.EP]
Abstract

International audience; Ten years after the successful landing of the HUYGENS probe on the surface of Titan, we reassess the complex permittivity measurements of the surface materials performed by the PWA-HASI experiment (Permittivity, Waves and Altimetry - Huygens Atmospheric Structure Instrument).The complex permittivity is inferred from the mutual impedance of a classical quadrupolar probe, ie. the ratio of the voltage measured by a receiving dipole over the current emitted by another dipole. Using a simple model of the quadrupole configuration, the dielectric constant of the material at the landing site was first estimated to be of the order of 1.8. A more realistic numerical model that took into account the influence of the HUYGENS gondola yielded a dielectric constant in the range 2-3 and a conductivity in the range 0.4 - 0.8 nS/m. due to uncertainties about the system geometry ( Grard et al., 2006). However, a puzzling experimental fact remains to be explained, namely a sudden variation of the amplitude and phase of the received voltage 11 mn after landing that cannot be associated with any lander mechanical disturbance. Permittivity estimations were based on the first 11 mn sequence.The present analysis takes advantage of a recent analysis of the landing process that provided more realistic final position and attitude for the HUYGENS lander (Schroder et al., 2012). The new results lie within former estimated ranges and attention is paid to their sensitivity to geometry and to the reference measurements collected immediately before landing. This point is particularly critical for the estimation of the conductivity.The complete data set has been analysed, including the sequence collected after the first 11 mn. We consider various scenarios that may explain the observed phase and amplitude discontinuity. We tested two layers ground models in order to investigate the possibility that the upper layer may have experienced a fast physical change due to deliquescence or outgasing. Unfortunately a rigid quadrupolar array measure the average electric properties of the ground and cannot detect any inhomogeneity.We present in addition the measurements made last May in the Dachstein ice cave in Austria, with a mockup of HUYGENS-PWA and a replica of the PP-SESAME instrument onboard the PHILAE lander of ROSETTA

Published
2014

29. First results of on-comet observations by SESAME/PP

Author

Schmidt, Walter, Seidensticker, Klaus J., Le Gall, Alice, Hamelin, Michel, Caujolle-Bert, Sylvain, Lethuillier, Anthony, and Grard, R.

Subjects
Rosetta, Kometen, Wassereis, PP, Philae, SESAME
Published
2014

30. Numerical simulations of PP-SESAME/Philae/ROSETTA operations during the Descent Phase and at the surface of the Churyumov-Gerasimenko nucleus

Author

Lethuillier, Anthony, Hamelin, Michel, Le Gall, Alice, Caujolle-Bert, Sylvain, Schmidt, Walter, Grard, Réjean, 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), 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), Finnish Meteorological Institute (FMI), Research and Scientific Support Department, ESTEC (RSSD), European Space Research and Technology Centre (ESTEC), European Space Agency (ESA)-European Space Agency (ESA), Cardon, Catherine, and Agence Spatiale Européenne = European Space Agency (ESA)-Agence Spatiale Européenne = European Space Agency (ESA)

Subjects
[PHYS.ASTR.EP] Physics [physics]/Astrophysics [astro-ph]/Earth and Planetary Astrophysics [astro-ph.EP], [PHYS.ASTR.EP]Physics [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], [SDU.ASTR.EP] Sciences of the Universe [physics]/Astrophysics [astro-ph]/Earth and Planetary Astrophysics [astro-ph.EP]
Abstract

The ROSETTA probe has never been so close to its target; the comet Churyumov-Gerasimenko that it will reach later this year. Among the instruments on board the lander, Philae, the Permittivity Probe (PP) experiment, which is part of the Surface Electric Sounding and Acoustic Monitoring Experiment (SESAME) package, will measure the low frequency complex permittivity (i.e. dielectric constant and electrical conductivity) of the first 2 meters of the subsurface of the cometary nucleus. At frequencies below 10 kHz, the electrical signature of the matter is especially sensitive to the presence of water ice and its temperature behavior. PP will thus allow to determine the water ice content in the near-surface and to monitor its diurnal and orbital variations thus providing essential insight on the activity and evolution of the cometary nucleus. The PP instrument is based on the quadrupole array technique, which employs a set of transmitter and receiver electrodes for emitting alternating currents into a medium of interest. The complex permittivity of the cometary surface material is determined by measuring the magnitude and phase shift of both the emitted currents and the resulting potential difference at a pair of receiver electrodes. This technique has been used for many decades on Earth and recently helped to determine the electrical properties of the Huygens landing site on Titan (PWA/HASI experiment on Cassini-Huygens). In the case of PP, 5 electrodes can be used: 2 receiver electrodes are integrated into the lander feet while the transmitter electrodes are mounted on the third foot and on 2 other instruments. In this paper we will present results from numerical simulations performed in order to model PP operations and prepare the scientific return of this experiment. Though simple in theory, the inference of the complex permittivity from PP measurements is not straightforward in practice. In particular, the actual environment of the electrodes (lander body, feet, harpoons...) must be accounted for since the presence of nearby conducting objects will affect the data. We have thus developed a numerical model of the electrodes in their environment using COMSOL Multiphysics®. A simple version of this model was validated by comparison to laboratory measurements and analytical calculations. This model was then used to simulate PP operations during the Descent Phase of the lander (i.e. in the void and as the ground gets closer) and once at the surface of the nucleus considering different types of surfaces. The first set of simulations will be very useful to better understand the calibration data that will be acquired after separation from the ROSETTA Orbiter while the second will illustrate the idealistic sensitivity of PP to the ground electrical properties.

Published
2014

31. Refining the analysis of PWA-HASI/Huygens to constrain Titan's surface electrical properties

Author

Hamelin, Michel, Lethuillier, Anthony, Le Gall, Alice, Béghin, Christian, Lopez-Moreno, J. J., Grard, R., Schwingenschuh, K., Jernej, I., 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), 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), Instituto de Astrofísica de Andalucía (IAA), Consejo Superior de Investigaciones Científicas [Madrid] (CSIC), Research and Scientific Support Department, ESTEC (RSSD), European Space Research and Technology Centre (ESTEC), Agence Spatiale Européenne = European Space Agency (ESA)-Agence Spatiale Européenne = European Space Agency (ESA), Space Research Institute of Austrian Academy of Sciences (IWF), Austrian Academy of Sciences (OeAW), and European Space Agency (ESA)-European Space Agency (ESA)

Subjects
[PHYS.ASTR.EP]Physics [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]
Abstract

International audience; Almost 10 years ago, the Huygens probe successfully landed on the surface of Titan, Saturn's biggest moon. The Permittivity, Waves and Altimetry (PWA-HASI) instrument onboard then investigated during 32 min the electrical properties at very low frequencies of the top meters of the surface. Preliminary results reported a relative dielectric constant of ~2 and a low electric conductivity. Since then, much has been learnt on the position of the Huygens probe after landing and on the surface characteristics of Titan. Here we describe the refined analysis of the PW A-HASI data and discuss composition scenarios.

Published
2014
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32. Laboratory and numerical simulations of the PP-SESAME instrument onboard Philae/ROSETTA for measuring cometary surface permittivity

Author

Hamelin, Michel, Le Gall, Alice, Caujolle-Bert, Sylvain, Ciarletti, Valérie, Lethuillier, Anthony, Schmidt, W., Grard, R., Witasse, O., Seidensticker, K., 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), Research and Scientific Support Department, ESTEC (RSSD), European Space Research and Technology Centre (ESTEC), European Space Agency (ESA)-European Space Agency (ESA), European Space Agency (ESA), German Aerospace Center (DLR), Agence Spatiale Européenne = European Space Agency (ESA)-Agence Spatiale Européenne = European Space Agency (ESA), Agence Spatiale Européenne = European Space Agency (ESA), and Cardon, Catherine

Subjects
[PHYS.ASTR.EP] Physics [physics]/Astrophysics [astro-ph]/Earth and Planetary Astrophysics [astro-ph.EP], [PHYS.ASTR.EP]Physics [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], [SDU.ASTR.EP] Sciences of the Universe [physics]/Astrophysics [astro-ph]/Earth and Planetary Astrophysics [astro-ph.EP]
Abstract

Measuring the complex permittivity of planetary surfaces provides insigth into their chemical composition and physical state. This can be done using a Mutual Impedance (MI) which consists in a four-electrode array generally (but not necessarily) in contact with the ground, working at a fixed frequency in the ELF-VLF (Extremely Low Frequency-Very Low Frequency) range with a dedicated electronic system [1]. The Permittivity Probe (PP) as part of the SESAME experiment onboard of the Philae/ROSETTA cometary lander relies on the MI concept. However the PP design had to be accomadated to the severe constraints of the Rosetta mission. In particular, parts of the landing gear (LG) and of other instruments are used as electrodes, introducing influences on the measurements to that need to be considered. Unfortunately, as it was not possible to perform it before launch, the calibration of the full system remains to be done. In order to prepare the analysis of PP data, a reduced size mockup of the LG built in DLR (Cologne, Germany) as well as a mockup-in-size of the instrument including a setup for Philae conductive body have been used for calibration tests in LATMOS (Guyancourt, France). Two configurations have been tested: i) tests as the instrument is in open space, as far as possible from walls, ceiling and floor, ii) Tests as the instrument is placed at several heights from a conductive floor. Such configurations aim at reproducing PP operations during the descent to the comet and the phase of first ground measurements. This would provide, together with numerical simulations under COMSOL™ a full model of the PP-SESAME instrument on Philae for the descent and first ground measurements configuration. Then slight corrections to this model would be possible using the in-flight calibration data to receive from the flight model during the descent on the comet. In this paper, we will present and discuss the results obtained with both nominal and reduced-in-size LGs in free space and in the vicinity of a conductive target (water). Such experiments and numerical simulations have never been done before and are crucial for understanding PP measurements. They also offer a unique opportunity to demonstrate the scientific interest of permittivity probes as it is anticipated that similar experiments will be proposed for future planetary missions including a lander or a rover. [1] Grard, R.: A quadrupolar array for measuring the complex permittivity of the ground: application to Earth prospection and planetary exploration, Meas. Sci. Technol.Vol. 1, p. 295, 1990.

Published
2013

34. Laboratory calibrations of the PP-SESAME instrument on Philae for measuring the cometary surface permittivity

Author

Hamelin, Michel, Le Gall, Alice, Caujolle-Bert, Sylvain, Schmidt, Walter, Grard, Réjean, Laasko, H., Ciarletti, Valérie, Seidensticker, K., 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), 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), Finnish Meteorological Institute (FMI), Research and Scientific Support Department, ESTEC (RSSD), European Space Research and Technology Centre (ESTEC), European Space Agency (ESA)-European Space Agency (ESA), German Aerospace Center (DLR), Cardon, Catherine, and Agence Spatiale Européenne = European Space Agency (ESA)-Agence Spatiale Européenne = European Space Agency (ESA)

Subjects
[PHYS.ASTR.EP] Physics [physics]/Astrophysics [astro-ph]/Earth and Planetary Astrophysics [astro-ph.EP], [PHYS.ASTR.EP]Physics [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], [SDU.ASTR.EP] Sciences of the Universe [physics]/Astrophysics [astro-ph]/Earth and Planetary Astrophysics [astro-ph.EP]
Abstract

The complex permittivity of terrestrial and planetary grounds can be derived from Mutual Impedance (MI) measurements using a four-electrode array [1]; the system is working at a fixed frequency with the electrodes not necessarily in contact with the ground and with a dedicated electronic system. This concept was used to build the Permittivity Probe (PP) as part of the SESAME experiment of the Philae Rosetta cometary lander. However severe constraints due to the payload facilities and to the particular environment lead to the actual design of the instrument. Unfortunately it was not possible to perform calibrations of the full system before lauch and the ground model consists of several parts used by various instruments. Here we report the results of basic calibration tests performed with a model of the Philae Landing Gear built in DLR. These tests involve only the three feet electrodes and a mockup of the the Philae body with very simple and well defined targets for characterizing the instrument. Further measurements on natural targets would be the next step.

Published
2013

35. A permittivity probe for the Ganymede lander

Author

Le Gall, Alice, Ciarletti, Valérie, Hamelin, Michel, Grard, Réjean, 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), and Cardon, Catherine

Subjects
[PHYS.ASTR.EP] Physics [physics]/Astrophysics [astro-ph]/Earth and Planetary Astrophysics [astro-ph.EP], [PHYS.ASTR.EP]Physics [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], [SDU.ASTR.EP] Sciences of the Universe [physics]/Astrophysics [astro-ph]/Earth and Planetary Astrophysics [astro-ph.EP]
Published
2013

36. Permittivity Probe on the Rosetta Lander Philae: Preparation for On-Comet-Phase

Author

Schmidt, Walter, Grard, Réjean, Hamelin, Michel, Ciarletti, Valérie, Le Gall, Alice, Caujolle-Bert, Sylvain, Cardon, Catherine, Finnish Meteorological Institute (FMI), Research and Scientific Support Department, ESTEC (RSSD), European Space Research and Technology Centre (ESTEC), Agence Spatiale Européenne = European Space Agency (ESA)-Agence Spatiale Européenne = European Space Agency (ESA), 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), and European Space Agency (ESA)-European Space Agency (ESA)

Subjects
[PHYS.ASTR.EP] Physics [physics]/Astrophysics [astro-ph]/Earth and Planetary Astrophysics [astro-ph.EP], [PHYS.ASTR.EP]Physics [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], [SDU.ASTR.EP] Sciences of the Universe [physics]/Astrophysics [astro-ph]/Earth and Planetary Astrophysics [astro-ph.EP]
Abstract

Mid of November 2014 the ESA Rosetta spacecraft will send its Lander Philae to the surface of the comet 67P/Churyumov-Gerasimenko. The three landing gear feet carry sensors of the Surface Electrical, Seismic and Acoustic Monitoring Experiments (SESAME), among them the Permittivity Probe (PP) [1]. Together with sensors attached to the MUPUS PEN and the APXS detector lid, PP features three transmitter electrodes and 2 receiver electrodes. Using any combination of two transmitters the quadrupole arrangement can measure the electrical properties of the comet surface material at different depths between 50 cm and about 2 m. The instrument is optimized for the detection of water ice inside the observed volume, its purity and temperature. For PP a critical mission phase is the descent towards the comet surface as after separation from the spacecraft and unfolding of the landing gear the instrument is for the first time in the real measurement configuration while the vacuum condition of space provides a known reference. This phase will be used for calibration of all signal disturbances like stray capacitances caused by cable connections, structure elements and other instruments. During the past year a special test scenario was developed and tested combining the operational requirements from several instruments into an integrated time line. Together with laboratory measurements using flight-equivalent material the electrical properties of the PP instrument network will be modeled. The results set the framework for the analysis of the on-comet observations under different electrode-combinations and geometry conditions. An observation sequence for the first days after landing was defined taking the different observational requirements into account. Reference: [1] Seidensticker, K.J., Thiel, K. and Schmidt, W., 2004: The Rosetta Lander Experiment SESAME and the new Target Comet 67P/Churyumov-Gerasimenko. Astrophys. Space Sci., 311,297-307.

Published
2013

37. Schumann resonance: a tool to study planetary atmospheric electricity and the origin and evolution of the solar system

Author

Hamelin, Michel, Simões, Fernando, Pfaff, Robert F., Béghin, Christian, Berthelier, Jean-Jacques, Chamberlin, Phillip C., Farrell, William M., Freudenreich, Henry, Grard, Réjean, Klenzing, Jeffrey, Lebreton, Jean-Pierre, Martin, Steven, Rowland, Douglas E., Yair, Yoav, 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), NASA Goddard Space Flight Center (GSFC), Laboratoire de physique et chimie de l'environnement (LPCE), Institut national des sciences de l'Univers (INSU - CNRS)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS), Research and Scientific Support Department, ESTEC (RSSD), European Space Research and Technology Centre (ESTEC), Agence Spatiale Européenne = European Space Agency (ESA)-Agence Spatiale Européenne = European Space Agency (ESA), 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), Open University of Israël, Université d'Orléans (UO)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), European Space Agency (ESA)-European Space Agency (ESA), and Cardon, Catherine

Subjects
[PHYS.PHYS.PHYS-AO-PH]Physics [physics]/Physics [physics]/Atmospheric and Oceanic Physics [physics.ao-ph], Astrophysics::Earth and Planetary Astrophysics, [PHYS.PHYS.PHYS-AO-PH] Physics [physics]/Physics [physics]/Atmospheric and Oceanic Physics [physics.ao-ph], Physics::Atmospheric and Oceanic Physics
Abstract

Investigation of extremely low frequency electromagnetic waves produced by lightning activity has been used to assist the characterization of a variety of phenomena related to atmospheric electricity in the Earth environment. Detection of Schumann Resonance spectral features of the earth-ionosphere cavity from outside the cavity offers new remote sensing capabilities to assess tropospheric-space weather connections, namely periodic patterns observed in a variety of tropospheric, ionospheric, and magnetospheric processes. A link between the water mixing ratio and atmospheric electrical conductivity makes Schumann resonance a suitable tool to assess volatile abundance of the outer planets, offering new capabilities to constrain thermodynamic parameters of the protosolar nebula from which the solar system evolved. In this work we discuss a technique and associated instrumentation to detect Schumann resonance signatures of planetary environments and subsequently to infer the fraction of volatiles and to investigate weather patterns in the gaseous envelopes of the giant planets.

Published
2012

38. Protecting Your Viability

Author

Gosselin, Eve and Hamelin, Michel

Subjects
Fraud -- Prevention, Banking, finance and accounting industries, Business, Business, general
Abstract

While no organization is immune to fraud, putting the right controls in place can help minimize the impact on a company's bottom line Fraud is a scourge on all businesses. [...]

Published
2001

39. Constraints on Titan's atmospheric conductivity and buried ocean depth, disclosed by the Schumann resonance

Author

Béghin, Christian, Hamelin, Michel, Sotin, C., Whitten, R.C., Berthelier, Jean-Jacques, Grard, Réjean, Simões, F., 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), 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), Jet Propulsion Laboratory (JPL), NASA-California Institute of Technology (CALTECH), SETI Institute, Research and Scientific Support Department, ESTEC (RSSD), European Space Research and Technology Centre (ESTEC), European Space Agency (ESA)-European Space Agency (ESA), NASA Goddard Space Flight Center (GSFC), ROUCHON, Nathalie, and Agence Spatiale Européenne = European Space Agency (ESA)-Agence Spatiale Européenne = European Space Agency (ESA)

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], [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]
Abstract

International audience; After six years of a thorough data analysis of the data collected by the Permittivity, Wave and Altimetry (PWA/HASI) experiment during the descent of the Huygens Probe through Titan's atmosphere in January 2005, we report the major findings inferred from the measurements of low frequency waves and atmospheric conductivity. The observations display a Schumann resonance trapped within Titan's atmospheric cavity. In this presentation, we describe the characteristics of the observed mode, that allow us to constrain the parameters of the ionospheric cavity and to infer the presence of a conductive water-ammonia ocean buried below the surface, at a likely depth of 70 ± 10 km.

Published
2011

40. Investigations of Titan electric environment and the Titan Electric Environment Package for the TandEM mission

Author

Simões, Fernando, Grard, R., Hamelin, Michel, Lopez Moreno, José Juan, Schwingenschuh, K., Béghin, C., Ferri, F., Molina-Cuberos, G., NASA Goddard Space Flight Center (GSFC), European Space Research and Technology Centre (ESTEC), Agence Spatiale Européenne = European Space Agency (ESA), 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), Instituto de Astrofísica de Andalucía (IAA), Consejo Superior de Investigaciones Científicas [Madrid] (CSIC), Austrian Academy of Sciences (OeAW), 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), Centro di Ateneo di Studi e Attività Spaziali 'Giuseppe Colombo' (CISAS), Università degli Studi di Padova = University of Padua (Unipd), and Universidad de Murcia

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

International audience

Published
2010

41. Surface and near surface dynamics on Phobos: conditions for grooves formation by impact ejecta

Author

Hamelin, Michel, PLANETO - 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]
Abstract

International audience; Phobos is orbiting around Mars close to the Roche limit. Therefore the surface material is loosely bounded andeasily ejected by impactors. Whereas dynamics in the close vicinity of Phobos has been studied for bothgeophysical and navigation reasons, the dynamics on the surface itself has not been studied to the same extent.Among many hypotheses about the formation of grooves on the surface of Phobos, it has been suggested thatthey could have been plowed by impact ejecta, but this was questioned using the arguments that blocks were notobserved at the end of the grooves and that the grooves do not run down slope. Then the study of surface andnear surface dynamics on Phobos can clarify the soundness of these controversial arguments.The gravitational field used is the ellipsoidal model of Davis, 1981, that describes as well the past and futurePhobos as it gets closer to Mars. The trajectory of a gliding test mass for any initial position and velocity iscomputed. Depending on initial conditions a gliding mass stay gliding or can take off after some distance.Generally the trajectories are not ‘down hill’ as the motion is strongly dependent on the velocity. Then the twoabove controversial arguments fail but the question remains. It is clearly proven that the sets of high latitudegrooves cannot have been dug by rolling ejecta. On the contrary the set of grooves issued from the Stickneycrater shows some similarities with the computed trajectories. The comparison between the observed groovesand the computed damped trajectories leads to a very low solid damping coefficient of ~0.1, not inconsistentwith other surface motion observations.

Published
2010

42. Comment on 'Evidence of electrical activity on Titan drawn from the Schumann resonances sent by Huygens probe' by J.A. Morente, J.A. Portí, A. Salinas, E.A. Navarro [doi: 10.1016/j.icarus.2008.02.004]

Author

Hamelin, Michel, Grard, R., López-Moreno, J.J., Schwingenschuh, K., Béghin, Christian, Berthelier, Jean-Jacques, Simões, F., 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), Research and Scientific Support Department, ESTEC (RSSD), European Space Research and Technology Centre (ESTEC), European Space Agency (ESA)-European Space Agency (ESA), Instituto de Astrofísica de Andalucía (IAA), Consejo Superior de Investigaciones Científicas [Madrid] (CSIC), Space Research Institute of Austrian Academy of Sciences (IWF), Austrian Academy of Sciences (OeAW), Laboratoire de physique et chimie de l'environnement (LPCE), Université d'Orléans (UO)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Agence Spatiale Européenne = European Space Agency (ESA)-Agence Spatiale Européenne = European Space Agency (ESA), and Institut national des sciences de l'Univers (INSU - CNRS)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Ionospheres, [SDU]Sciences of the Universe [physics], Titan, Instrumentation, Lightning
Abstract

International audience; Morente et al. [J.A. Morente, J.A. Portí, A. Salinas, E.A. Navarro, 2008. Icarus, doi: 10.1016/j.icarus.2008.02.004] have recently presented a new analysis of the Permittivity, Wave and Altimetry (PWA) measurements made during the descent of the Huygens Probe through the atmosphere of Titan. They claimed the identification of several Schumann resonance harmonics and concluded in favor of a lightning activity on Titan. We report here several reasons for not endorsing this paper.

Published
2009

43. Measurements of dielectric properties of tholins in a cyrogenic environment

Author

Simoes, Fernando, Cernogora, Guy, Correia, Jean-Jacques, Hamelin, Michel, Ruffie, G., Szopa, Cyril, 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), PLANETO - 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 Centre National de la Recherche Scientifique (CNRS)

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

International audience

Published
2009

44. Phobos grooves formation from Stickney impact ejecta: a simulation

Author

Hamelin, Michel, PLANETO - 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]
Abstract

International audience; Although grooves are common on asteroids, onPhobos the grooves have been the subject of manyvarious formation hypotheses for two reasons: thefact that Phobos is orbiting around Mars close tothe Roche limit that implies an unusual gravityenvironment, and also the fact that the huge craterimpact, Stickney, seems to be related at least to afamily of grooves radial to this crater. However,some authors claim that these grooves could havebeen formed not from the Stickney impact, butfrom martian crater ejecta hitting Phobos.The present study explores the first idea bycomputing the trajectory of a test mass gliding onthe surface of Phobos for any initial position andvelocity. An ellipsoidal model of Phobos is usedfor both the gravity and surface geometry.Depending on these initial conditions a glidingmass stay gliding or can take off after somedistance. Generally the trajectories are not ‘downhill’ as the motion is strongly dependent on thevelocity. Then the main objections to thehypothesis that gliding or rolling blocks couldhave dug these grooves fail.As the Stickney impact occurred at largerdistances from Mars, the study is extended to theancient Phobos in its drift towards Mars and thenthe various hypotheses for the grooves formationare discussed.

Published
2009

45. Philae Cometary Permittivity Probe model and operations with a reduced

Author

Hamelin, Michel, Simoës, Fernando, Schmidt, W., 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), and Finnish Meteorological Institute (FMI)

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

International audience; The Permittivity Probe (PP) is a subsystem of the SESAME instrument on the Philae lander of the Rosetta mission to comet Churyumov-Gerasimenko. The probe consists of a system of 2 receiving and 3 transmitting electrodes which can be operated in different quadrupolar probe configurations, involving only two receivers and two transmitters at any given time. However, the system of electrodes is strongly influenced by the vicinity of the lander body and other grounded elements that work as additional electrodes. During the operational phases of the mission only one of the transmitter electrodes will always be available, as the two others depend on the deployment status of the host instruments they are attached to. We have built an electrical model of Philae to study non conventional ways for measuring the cometary permittivity with a reduced set of electrodes and the distorting influence of the various lander structure elements.

Published
2009

46. PWA-HASI Measurements of Titan Surface Permittivity at Huygens Landing Point

Author

Hamelin, Michel, Simões, Fernando, Béghin, Christian, López-Moreno, José J., Grard, Rejean, Schwingenschuh, K., Trautner, Roland, Falkner, P., Ferri, Francesca, Fulchignoni, Marcello, 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), Pôle Planétologie du LESIA, Laboratoire d'études spatiales et d'instrumentation en astrophysique = Laboratory of Space Studies and Instrumentation in Astrophysics (LESIA), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)-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)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)

Subjects
[PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph]
Abstract

International audience

Published
2007

47. Balloon flight validation of ARES, an atmospheric electricity instrument proposed for the Exomars-GEP

Author

Berthelier, Jean-Jacques, Godefroy, Michel, Hamelin, Michel, Seran, Elena, Simoes, F., Yahi, S., Centre d'étude des environnements terrestre et planétaires (CETP), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), and Cardon, Catherine

Subjects
[SDU.ASTR]Sciences of the Universe [physics]/Astrophysics [astro-ph], [PHYS.PHYS.PHYS-PLASM-PH]Physics [physics]/Physics [physics]/Plasma Physics [physics.plasm-ph], [PHYS.PHYS.PHYS-PLASM-PH] Physics [physics]/Physics [physics]/Plasma Physics [physics.plasm-ph], [SDU.ASTR] Sciences of the Universe [physics]/Astrophysics [astro-ph]
Published
2007

48. Conductivity and electron density in Titan's atmosphere as deduced from Mutual Impedance measurements by the PWA-HASI instrument on HUYGENS

Author

Hamelin, Michel, Béghin, Christian, Brown, V. J., Grard, Rejean, Jernej, I., López-Moreno, José J., Schwingenschuh, K., Simões, Fernando, Trautner, Roland, Molina-Cuberos, Gregorio J., Berthelier, Jean-Jacques, Chabassière, M., Falkner, P., Ferri, Francesca, Fulchignoni, Marcello, Hofe, R., Jeronimo, J. J., Lara, Luisa M., Rodrigo, Rafael, Svedhem, Håkan, Tokano, Tetsuya, Centre d'étude des environnements terrestre et planétaires (CETP), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de physique et chimie de l'environnement (LPCE), Institut national des sciences de l'Univers (INSU - CNRS)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS), Instituto de Astrofísica de Andalucía (IAA), Consejo Superior de Investigaciones Científicas [Madrid] (CSIC), European Space Research and Technology Centre (ESTEC), Agence Spatiale Européenne = European Space Agency (ESA), Institut für Weltraumforschung = Space Research institute [Graz] (IWF), Osterreichische Akademie der Wissenschaften (ÖAW), Centro di Ateneo di Studi e Attività Spaziali 'Giuseppe Colombo' (CISAS), Università degli Studi di Padova = University of Padua (Unipd), 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), Pôle Planétologie du LESIA, Laboratoire d'études spatiales et d'instrumentation en astrophysique = Laboratory of Space Studies and Instrumentation in Astrophysics (LESIA), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), and Universität zu Köln = University of Cologne

Subjects
[PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph]
Abstract

International audience; During the descent of the HUYGENS Probe through the atmosphere of Titan, January 14th, 2005, the permittivity, Waves and Altimetry (PWA), a subsystem of the HUYGENS Atmospheric Structure Instrument (HASI) detected an ionized layer around the altitude of 60 km with two different instruments, the Relaxation Probe (RP) and the Mutual Impedance Probe (MIP). For both instruments a more detailed data analysis, including unforeseen environmental effects, was necessary to reach precise quantitative estimations of the electrical conductivity. The present work is dedicated to the MIP data analysis. New laboratory tests have been performed to correct and validate the calibration data. Temperature effects have been included and two different numerical models of MIP electrodes and circuits in the HUYGENS body environment have been used. The effect of motion of HUYGENS in the ionized atmosphere that was neglected in the first analysis is revealed and analytical estimations of this effect allow to derive more accurate values of the conductivity. The final results are discussed, compared to the RP results and electron density profiles are deduced showing more precisely the lower ionized layer.

Published
2006

49. Electric Conductivity And Waves In The Atmosphere Of Titan From The Pwa-hasi Instrument On The Huygens Probe

Author

Hamelin, Michel, Brown, V. J., Béghin, Christian, Chabassière, M., Falkner, P., Ferri, Francesca, Fulchignoni, Marcello, Grard, Rejean, Hofe, R., Jernej, I., Lara, Luisa M., López-Moreno, José J., Molina-Cuberos, Gregorio J., Rodrigo, Rafael, Schwingenschuh, K., Simões, Fernando, Trautner, Roland, 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), Pôle Planétologie du LESIA, Laboratoire d'études spatiales et d'instrumentation en astrophysique = Laboratory of Space Studies and Instrumentation in Astrophysics (LESIA), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)-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)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)

Subjects
[PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph]
Abstract

International audience

Published
2006

50. The characteristics of Titan's atmosphere by the Huygens Atmospheric Structure Instrument (HASI) measurements

Author

Fulchignoni, Marcello, Ferri, Francesca, Colombatti, C., Zarnecki, John C., Harri, A.-M., Grard, Rejean, Hamelin, Michel, Schwingenschuh, K., López-Moreno, José J., Angrilli, Francesco, 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), Pôle Planétologie du LESIA, Laboratoire d'études spatiales et d'instrumentation en astrophysique = Laboratory of Space Studies and Instrumentation in Astrophysics (LESIA), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)-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)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)

Subjects
[PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph]
Abstract

International audience

Published
2006

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