@article{ArridgeAchilleosAgarwaletal.2014, author = {Arridge, Christopher S. and Achilleos, N. and Agarwal, Jessica and Agnor, C. B. and Ambrosi, R. and Andre, N. and Badman, S. V. and Baines, K. and Banfield, D. and Barthelemy, M. and Bisi, M. M. and Blum, J. and Bocanegra-Bahamon, T. and Bonfond, B. and Bracken, C. and Brandt, P. and Briand, C. and Briois, C. and Brooks, S. and Castillo-Rogez, J. and Cavalie, T. and Christophe, B. and Coates, Andrew J. and Collinson, G. and Cooper, J. F. and Costa-Sitja, M. and Courtin, R. and Daglis, I. A. and De Pater, Imke and Desai, M. and Dirkx, D. and Dougherty, M. K. and Ebert, R. W. and Filacchione, Gianrico and Fletcher, Leigh N. and Fortney, J. and Gerth, I. and Grassi, D. and Grodent, D. and Gr{\"u}n, Eberhard and Gustin, J. and Hedman, M. and Helled, R. and Henri, P. and Hess, Sebastien and Hillier, J. K. and Hofstadter, M. H. and Holme, R. and Horanyi, M. and Hospodarsky, George B. and Hsu, S. and Irwin, P. and Jackman, C. M. and Karatekin, O. and Kempf, Sascha and Khalisi, E. and Konstantinidis, K. and Kruger, H. and Kurth, William S. and Labrianidis, C. and Lainey, V. and Lamy, L. L. and Laneuville, Matthieu and Lucchesi, D. and Luntzer, A. and MacArthur, J. and Maier, A. and Masters, A. and McKenna-Lawlor, S. and Melin, H. and Milillo, A. and Moragas-Klostermeyer, Georg and Morschhauser, Achim and Moses, J. I. and Mousis, O. and Nettelmann, N. and Neubauer, F. M. and Nordheim, T. and Noyelles, B. and Orton, G. S. and Owens, Mathew and Peron, R. and Plainaki, C. and Postberg, F. and Rambaux, N. and Retherford, K. and Reynaud, Serge and Roussos, E. and Russell, C. T. and Rymer, Am. and Sallantin, R. and Sanchez-Lavega, A. and Santolik, O. and Saur, J. and Sayanagi, Km. and Schenk, P. and Schubert, J. and Sergis, N. and Sittler, E. C. and Smith, A. and Spahn, Frank and Srama, Ralf and Stallard, T. and Sterken, V. and Sternovsky, Zoltan and Tiscareno, M. and Tobie, G. and Tosi, F. and Trieloff, M. and Turrini, D. and Turtle, E. P. and Vinatier, S. and Wilson, R. and Zarkat, P.}, title = {The science case for an orbital mission to Uranus: Exploring the origins and evolution of ice giant planets}, series = {Planetary and space science}, volume = {104}, journal = {Planetary and space science}, publisher = {Elsevier}, address = {Oxford}, issn = {0032-0633}, doi = {10.1016/j.pss.2014.08.009}, pages = {122 -- 140}, year = {2014}, abstract = {Giant planets helped to shape the conditions we see in the Solar System today and they account for more than 99\% of the mass of the Sun's planetary system. They can be subdivided into the Ice Giants (Uranus and Neptune) and the Gas Giants (Jupiter and Saturn), which differ from each other in a number of fundamental ways. Uranus, in particular is the most challenging to our understanding of planetary formation and evolution, with its large obliquity, low self-luminosity, highly asymmetrical internal field, and puzzling internal structure. Uranus also has a rich planetary system consisting of a system of inner natural satellites and complex ring system, five major natural icy satellites, a system of irregular moons with varied dynamical histories, and a highly asymmetrical magnetosphere. Voyager 2 is the only spacecraft to have explored Uranus, with a flyby in 1986, and no mission is currently planned to this enigmatic system. However, a mission to the uranian system would open a new window on the origin and evolution of the Solar System and would provide crucial information on a wide variety of physicochemical processes in our Solar System. These have clear implications for understanding exoplanetary systems. In this paper we describe the science case for an orbital mission to Uranus with an atmospheric entry probe to sample the composition and atmospheric physics in Uranus' atmosphere. The characteristics of such an orbiter and a strawman scientific payload are described and we discuss the technical challenges for such a mission. This paper is based on a white paper submitted to the European Space Agency's call for science themes for its large-class mission programme in 2013.}, language = {en} } @article{ZaourarHamoudiHolschneideretal.2013, author = {Zaourar, Naima and Hamoudi, Mohamed and Holschneider, Matthias and Mandea, Mioara}, title = {Fractal dynamics of geomagnetic storms}, series = {Arabian journal of geosciences}, volume = {6}, journal = {Arabian journal of geosciences}, number = {6}, publisher = {Springer}, address = {Heidelberg}, issn = {1866-7511}, doi = {10.1007/s12517-011-0487-0}, pages = {1693 -- 1702}, year = {2013}, abstract = {We explore fluctuations of the horizontal component of the Earth's magnetic field to identify scaling behaviour of the temporal variability in geomagnetic data recorded by the Intermagnet observatories during the solar cycle 23 (years 1996 to 2005). In this work, we use the remarkable ability of scaling wavelet exponents to highlight the singularities associated with discontinuities present in the magnetograms obtained at two magnetic observatories for six intense magnetic storms, including the sudden storm commencements of 14 July 2000, 29-31 October and 20-21 November 2003. In the active intervals that occurred during geomagnetic storms, we observe a rapid and unidirectional change in the spectral scaling exponent at the time of storm onset. The corresponding fractal features suggest that the dynamics of the whole time series is similar to that of a fractional Brownian motion. Our findings point to an evident relatively sudden change related to the emergence of persistency of the fractal power exponent fluctuations precedes an intense magnetic storm. These first results could be useful in the framework of extreme events prediction studies.}, language = {en} }