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491 results on '"Dehant, V"'

165. A joint inversion method of electromagnetic, geodetic and seismological data for the study of planetary interiors

Author

Rivoldini, A., Verhoeven, O., Vacher, P., Dehant, V., Menvielle, M., Mocquet, A., Choblet, G., Interior Netlander Team, Mars, Laboratoire de Planétologie et Géodynamique [UMR 6112] (LPG), Université d'Angers (UA)-Université de Nantes - UFR des Sciences et des Techniques (UN UFR ST), and Université de Nantes (UN)-Université de Nantes (UN)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)

Subjects
ComputingMilieux_MISCELLANEOUS
Abstract

International audience

Published
2003

166. Mission Netlander : la synergie entre les expériences Magnet-Neige-Seis comme clef de voûte d'une nouvelle modélisation de la structure interne de Mars

Author

Verhoeven, O., Rivoldini, A., Dehant, V., Menvielle, M., Mocquet, A., Al., Et, Laboratoire de Planétologie et Géodynamique [UMR 6112] (LPG), Université d'Angers (UA)-Université de Nantes - UFR des Sciences et des Techniques (UN UFR ST), and Université de Nantes (UN)-Université de Nantes (UN)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)

Subjects
ComputingMilieux_MISCELLANEOUS
Abstract

National audience

Published
2002

167. Modeling Mars' interior

Author

Verhoeven, O., Dehant, V., Menvielle, M., Mocquet, A., Vacher, P., Al., Et, Laboratoire de Planétologie et Géodynamique [UMR 6112] (LPG), Université d'Angers (UA)-Université de Nantes - UFR des Sciences et des Techniques (UN UFR ST), and Université de Nantes (UN)-Université de Nantes (UN)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)

Subjects
ComputingMilieux_MISCELLANEOUS
Abstract

International audience

Published
2002

168. Modélisation de la structure interne de Mars

Author

Verhoeven, O., Dehant, V., Menvielle, M., Mocquet, A., Vacher, P., Al., Et, Laboratoire de Planétologie et Géodynamique [UMR 6112] (LPG), Université d'Angers (UA)-Université de Nantes - UFR des Sciences et des Techniques (UN UFR ST), and Université de Nantes (UN)-Université de Nantes (UN)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)

Subjects
ComputingMilieux_MISCELLANEOUS
Abstract

National audience

Published
2002

169. Penetrators for in situ subsurface investigations of Europa

Author

na, Gowen, R., Smith, A., Fortes, A., Barber, S., Brown, P., Church, P., Collinson, G., Coates, A., Collins, G., Crawford, I., Dehant, V., Chela-Flores, J., Griffiths, A., Grindrod, P., Gurvits, L., Hagermann, A., Hussmann, H., Jaumann, R., Jones, A., Joy, K., Karatekin, O., Miljkovic, Katarina, Palomba, E., Pike, W., Prieto-Ballesteros, O., Raulin, F., Sephton, M., Sheridan, S., Sims, M., Storrie-Lombardi, M., Ambrosi, R., Fielding, J., Fraser, G., Gao, Y., Jones, G., Kargl, G., Karl, W., MacAgnano, A., Mukherjee, A., Muller, J., Phipps, A., Pullan, D., Richter, L., Sohl, F., Snape, J., Sykes, J., Wells, N., na, Gowen, R., Smith, A., Fortes, A., Barber, S., Brown, P., Church, P., Collinson, G., Coates, A., Collins, G., Crawford, I., Dehant, V., Chela-Flores, J., Griffiths, A., Grindrod, P., Gurvits, L., Hagermann, A., Hussmann, H., Jaumann, R., Jones, A., Joy, K., Karatekin, O., Miljkovic, Katarina, Palomba, E., Pike, W., Prieto-Ballesteros, O., Raulin, F., Sephton, M., Sheridan, S., Sims, M., Storrie-Lombardi, M., Ambrosi, R., Fielding, J., Fraser, G., Gao, Y., Jones, G., Kargl, G., Karl, W., MacAgnano, A., Mukherjee, A., Muller, J., Phipps, A., Pullan, D., Richter, L., Sohl, F., Snape, J., Sykes, J., and Wells, N.

Abstract

We present the scientific case for inclusion of penetrators into the Europan surface, and the candidate instruments which could significantly enhance the scientific return of the joint ESA/NASA Europa-Jupiter System Mission (EJSM). Moreover, a surface element would provide an exciting and inspirational mission highlight which would encourage public and political support for the mission. Whilst many of the EJSM science goals can be achieved from the proposed orbital platform, only surface elements can provide key exploration capabilities including direct chemical sampling and associated astrobiological material detection, and sensitive habitability determination. A targeted landing site of upwelled material could provide access to potential biological material originating from deep beneath the ice. Penetrators can also enable more capable geophysical investigations of Europa (and Ganymede) interior body structures, mineralogy, mechanical, magnetic, electrical and thermal properties. They would provide ground truth, not just for the orbital observations of Europa, but could also improve confidence of interpretation of observations of the other Jovian moons. Additionally, penetrators on both Europa and Ganymede, would allow valuable comparison of these worlds, and gather significant information relevant to future landed missions. The advocated low mass penetrators also offer a comparatively low cost method of achieving these important science goals. A payload of two penetrators is proposed to provide redundancy, and improve scientific return, including enhanced networked seismometer performance and diversity of sampled regions. We also describe the associated candidate instruments, penetrator system architecture, and technical challenges for such penetrators, and include their current status and future development plans. © 2010 COSPAR. Published by Elsevier Ltd. All rights reserved.

Published
2011

170. Contributions of Tidal Poisson Terms in the Theory of the Nutation of a Nonrigid Earth

Author

Dehant, V., Folgueira López, Marta, Rambaux, N., Lambert, S.B., Dehant, V., Folgueira López, Marta, Rambaux, N., and Lambert, S.B.

Abstract

The tidal potential generated by bodies in the solar system contains Poisson terms, i.e., periodic terms with linearly time-dependent amplitudes. The influence of these terms in the Earth's rotation, although expected to be small, could be of interest in the present context of high accuracy modelling. We have studied their contribution in the rotation of a non rigid Earth with elastic mantle and liquid core. Starting from the Liouville equations, we computed analytically the contribution in the wobble and showed that the presently-used transfer function must be supplemented by additional terms to be used in convolution with the amplitude of the Poisson terms of the potential and inversely proportional to (sigma - sigma(n))(2) where sigma is the forcing frequency and sigma(n) are the eigenfrequencies associated with the retrograde free core nutation and the Chandler wobble. These results have been detailed in a paper that we published in Astron. Astrophys. in 2007. In the present paper, we further examine the contribution from the core on the wobble and the nutation. In particular, we examine the contribution on extreme cases such as for wobble frequencies near the Free Core Nutation Frequency (FCN) or for long period nutations. In addition to the analytical computation, we used a time-domain approach through a numerical model to examine the core and mantle motions and discuss the analytical results.

Published
2009

171. Impact of tidal Poisson terms on nonrigid Earth rotation

Author

Folgueira López, Marta, Dehant, V., Lambert, S.B., Rambaux, N., Folgueira López, Marta, Dehant, V., Lambert, S.B., and Rambaux, N.

Abstract

Context. The tidal potential generated by bodies in the solar system contains Poisson terms, i.e., periodic terms with linearly time-dependent amplitudes. The influence of these terms on the Earth's rotation, although expected to be small, is of interest for high accuracy modeling. Aims. Therefore, we study their contribution to the rotation of a non-rigid Earth with an elastic mantle and liquid core. Methods. Starting from Liouville's equations, and following an analytical treatment, we obtain the relations accounting for Poisson terms in the forcing and providing the solution for the wobble. Results. We show that the transfer function between rigid and non rigid nutation amplitudes, as usually defined in the literature, must be supplemented by additional terms proportional to the amplitude of the Poisson term of the potential. These new terms are inversely proportional to (sigma - sigma(N))(2) where sigma is the forcing frequency and sigma(N) are the eigenfrequencies associated with the retrograde free core nutation and the Chandler wobble. The highest contribution to the nutation is 6 mu as (Delta psi) on the term 2l' - 2F + 2D - 2 Omega and remains below 1 mu as for the other terms. A contribution of 88 mu as/cy is found to the obliquity rate. We evaluate the variations of the third component of the wobble of the Earth and of the core in response to a zonal tidal potential, and show that there is no significant change., Unidad Deptal. de Astronomía y Geodesia, Fac. de Ciencias Matemáticas, TRUE, pub

Published
2007

172. MEMO- Mars environment and escape orbiter:Proposal for ESA Cosmic Vision 2015-2025

Author

Barabash, S., Breuer, D., Chassefiere, E., Coates, A., Dehant, V., Forget, F., Fouchet, T., Langlais, B, Lammer, H., Leblanc, F., Lewis, S, Mandea, M., Menvielle, M., Pais, A, Read, P., Sotin, C., Tarits, P., Lopez-Valverde, M., Barabash, S., Breuer, D., Chassefiere, E., Coates, A., Dehant, V., Forget, F., Fouchet, T., Langlais, B, Lammer, H., Leblanc, F., Lewis, S, Mandea, M., Menvielle, M., Pais, A, Read, P., Sotin, C., Tarits, P., and Lopez-Valverde, M.

Published
2007

182. Mars Environment and Magnetic Orbiter Scientific and Measurement Objectives

Author

Leblanc, F., primary, Langlais, B., additional, Fouchet, T., additional, Barabash, S., additional, Breuer, D., additional, Chassefière, E., additional, Coates, A., additional, Dehant, V., additional, Forget, F., additional, Lammer, H., additional, Lewis, S., additional, Lopez-Valverde, M., additional, Mandea, M., additional, Menvielle, M., additional, Pais, A., additional, Paetzold, M., additional, Read, P., additional, Sotin, C., additional, Tarits, P., additional, and Vennerstrom, S., additional

Published
2009
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186. Mars environment and magnetic orbiter model payload

Author

Langlais, B., primary, Leblanc, F., additional, Fouchet, T., additional, Barabash, S., additional, Breuer, D., additional, Chassefière, E., additional, Coates, A., additional, Dehant, V., additional, Forget, F., additional, Lammer, H., additional, Lewis, S., additional, Lopez-Valverde, M., additional, Mandea, M., additional, Menvielle, M., additional, Pais, A., additional, Paetzold, M., additional, Read, P., additional, Sotin, C., additional, Tarits, P., additional, Vennerstrom, S., additional, Branduardi-Raymont, G., additional, Cremonese, G., additional, Merayo, J. G. M., additional, Ott, T., additional, Rème, H., additional, Trotignon, J. G., additional, and Walhund, J. E., additional

Published
2008
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197. Division I Working Group on “Nomenclature for Fundamental Astronomy” (NFA)

Author

Capitaine, Nicole, primary, Andrei, A.H., additional, Calabretta, M., additional, Dehant, V., additional, Fukushima, T., additional, Guinot, B., additional, Hohenkerk, C., additional, Kaplan, G., additional, lioner, S., additional, Kovalevsky, J., additional, Kumkova, I., additional, Ma, C., additional, McCarthy, D.D., additional, Seidelmann, P.K., additional, and Wallace, P.T., additional

Published
2005
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