Showing papers by "Baptiste Cecconi published in 2012"
TL;DR: In this article, a campaign of FUV observations of Uranus obtained in November 2011 with the Hubble Space Telescope (HST) during active solar wind conditions was presented, together with some obtained in 1998.
Abstract: [1] This study is based on multi-planet multi-wavelength observations of planetary aurorae throughout the heliosphere, acquired along the propagation path of a series of consecutive interplanetary shocks. The underlying motivation to track the shocks was to increase the probability of detection of auroral emissions at Uranus. Despite several Earth-based attempts in the past few years, at Far-UV (FUV) and Near-IR (NIR) wavelengths, such emissions have never been unambiguously re-observed since their discovery by Voyager 2 in 1986. Here, we present a campaign of FUV observations of Uranus obtained in November 2011 with the Hubble Space Telescope (HST) during active solar wind conditions. We positively identify auroral signatures in several of these HST measurements, together with some obtained in 1998, representing the first images of Uranus' aurorae. We analyze their characteristics and discuss the implications for the asymmetric Uranian magnetosphere and its highly variable interaction with the solar wind flow from near-solstice (1986) to near-equinox (2011) configurations.
64 citations
University of Toulouse1, Paris Diderot University2, California Institute of Technology3, Centre national de la recherche scientifique4, Institut de mécanique céleste et de calcul des éphémérides5, Radboud University Nijmegen6, German Aerospace Center7, Southwest Research Institute8, Joint Institute for VLBI in Europe9, Delft University of Technology10, University of British Columbia11, Planetary Science Institute12, Johns Hopkins University Applied Physics Laboratory13, University of Nantes14, University of Notre Dame15, Technical University of Denmark16, Leiden University17, University of Glasgow18
TL;DR: Farside Explorer as discussed by the authors is a medium-size mission to the farside of the Moon consisting of two landers and an instrumented relay satellite, which is a unique scientific platform in that it is shielded from terrestrial radio-frequency interference, it can be continuously monitored from the Earth-Moon L2 Lagrange point, and there is a complete lack of reflected solar illumination from Earth.
Abstract: Farside Explorer is a proposed Cosmic Vision medium-size mission to the farside of the Moon consisting of two landers and an instrumented relay satellite. The farside of the Moon is a unique scientific platform in that it is shielded from terrestrial radio-frequency interference, it recorded the primary differentiation and evolution of the Moon, it can be continuously monitored from the Earth–Moon L2 Lagrange point, and there is a complete lack of reflected solar illumination from the Earth. Farside Explorer will exploit these properties and make the first radio-astronomy measurements from the most radio-quiet region of near-Earth space, determine the internal structure and thermal evolution of the Moon, from crust to core, and quantify impact hazards in near-Earth space by the measurement of flashes generated by impact events. The Farside Explorer flight system includes two identical solar-powered landers and a science/telecommunications relay satellite to be placed in a halo orbit about the Earth–Moon L2 Lagrange point. One lander would explore the largest and oldest recognized impact basin in the Solar System— the South Pole–Aitken basin—and the other would investigate the primordial highlands crust. Radio astronomy, geophysical, and geochemical instruments would be deployed on the surface, and the relay satellite would continuously monitor the surface for impact events.
64 citations
TL;DR: In this article, the authors analyze the planetary and exoplanetary science that can be carried out with precursor as well as future low frequency radio instruments on the Moon, assessing the limiting noise sources, comparing them to the average and peak spectra of all planetary radio components as they will be seen from the Lunar surface or orbit.
64 citations
University College London1, Birkbeck, University of London2, Queen Mary University of London3, Centre national de la recherche scientifique4, Jet Propulsion Laboratory5, University of Oxford6, University of Franche-Comté7, University of Rostock8, University of California, Los Angeles9, University of Leicester10, Cornell University11, University of Nantes12, Swedish Institute of Space Physics13, Joseph Fourier University14, University of Buenos Aires15, Johns Hopkins University Applied Physics Laboratory16, Boston University17, Max Planck Society18, Armagh Observatory19, Goddard Space Flight Center20, Imperial College London21, Southwest Research Institute22, University of California, Santa Cruz23, University of Liège24, University of Colorado Boulder25, University of Liverpool26, Royal Observatory of Belgium27, University of Iowa28, Université de Namur29, University of California, Berkeley30, University of Cologne31, University of the Basque Country32, Lunar and Planetary Institute33, Academy of Athens34, University of Bristol35
TL;DR: The Uranus Pathfinder (UP) mission as mentioned in this paper was proposed to the European Space Agency's M3 call for medium-class missions in 2010 and proposed to be the first orbiter of an Ice Giant planet.
Abstract: The “Ice Giants” Uranus and Neptune are a different class of planet compared to Jupiter and Saturn. Studying these objects is important for furthering our understanding of the formation and evolution of the planets, and unravelling the fundamental physical and chemical processes in the Solar System. The importance of filling these gaps in our knowledge of the Solar System is particularly acute when trying to apply our understanding to the numerous planetary systems that have been discovered around other stars. The Uranus Pathfinder (UP) mission thus represents the quintessential aspects of the objectives of the European planetary community as expressed in ESA’s Cosmic Vision 2015–2025. UP was proposed to the European Space Agency’s M3 call for medium-class missions in 2010 and proposed to be the first orbiter of an Ice Giant planet. As the most accessible Ice Giant within the M-class mission envelope Uranus was identified as the mission target. Although not selected for this call the UP mission concept provides a baseline framework for the exploration of Uranus with existing low-cost platforms and underlines the need to develop power sources suitable for the outer Solar System. The UP science case is based around exploring the origins, evolution, and processes at work in Ice Giant planetary systems. Three broad themes were identified: (1) Uranus as an Ice Giant, (2) An Ice Giant planetary system, and (3) An asymmetric magnetosphere. Due to the long interplanetary transfer from Earth to Uranus a significant cruise-phase science theme was also developed. The UP mission concept calls for the use of a Mars Express/Rosetta-type platform to launch on a Soyuz–Fregat in 2021 and entering into an eccentric polar orbit around Uranus in the 2036–2037 timeframe. The science payload has a strong heritage in Europe and beyond and requires no significant technology developments.
63 citations
Centre national de la recherche scientifique1, University of California, Los Angeles2, Cornell University3, University of Porto4, Imperial College London5, University of Oxford6, Technical University of Lisbon7, Braunschweig University of Technology8, Lowell Observatory9, Free University of Berlin10, University of Bremen11, Alenia Aeronautica12, Heidelberg University13, Joint Institute for VLBI in Europe14, University of Cologne15, Hampton University16, Empik17, University of Stuttgart18, Pierre-and-Marie-Curie University19
TL;DR: The OSS mission as discussed by the authors is an M-class mission to explore the Neptune system almost half a century after flyby of the Voyager 2 spacecraft, which revealed the dynamics of Neptune's atmosphere and evidence of ring arcs above Neptune.
Abstract: The present OSS mission continues a long and bright tradition by associating the communities of fundamental physics and planetary sciences in a single mission with ambitious goals in both domains. OSS is an M-class mission to explore the Neptune system almost half a century after flyby of the Voyager 2 spacecraft. Several discoveries were made by Voyager 2, including the Great Dark Spot (which has now disappeared) and Triton's geysers. Voyager 2 revealed the dynamics of Neptune's atmosphere and found four rings and evidence of ring arcs above Neptune. Benefiting from a greatly improved instrumentation, it will result in a striking advance in the study of the farthest planet of the Solar System. Furthermore, OSS will provide a unique opportunity to visit a selected Kuiper Belt object subsequent to the passage of the Neptunian system. It will consolidate the hypothesis of the origin of Triton as a KBO captured by Neptune, and improve our knowledge on the formation of the Solar system. The probe will embark instruments allowing precise tracking of the probe during cruise. It allows to perform the best controlled experiment for testing, in deep space, the General Relativity, on which is based all the models of Solar system formation. OSS is proposed as an international cooperation between ESA and NASA, giving the capability for ESA to launch an M-class mission towards the farthest planet of the Solar system, and to a Kuiper Belt object. The proposed mission profile would allow to deliver a 500 kg class spacecraft. The design of the probe is mainly constrained by the deep space gravity test in order to minimise the perturbation of the accelerometer measurement.
38 citations
TL;DR: In this article, the authors present a review of spectral intensity, variability and sources of radio emissions at Jupiter, as seen from the vicinity of Europa or Ganymede, and show that this radio noise has to be taken into account very early in the observation planning and strategies for both JGO and JEO.
34 citations
TL;DR: In this article, the authors showed that ground-based radio astronomy lets us detect Saturn's lightning with a high degree of reliability despite terrestrial interferences, which is the necessary basis for further detailed study of the temporal and spectral characteristics of the SEDs with ground based radio telescopes, in particular a correlation of 0.77 ± 0.15 between the average intensity of storms and the e-folding time.
28 citations
TL;DR: In this article, a goniopolarimetric (GP) inversion of a signal measured on non-orthogonal antennas using the Singular Value Decomposition (SVD) technique is described.
Abstract: [1] Type III radio bursts are intense solar radio emissions generated by beams of energetic electrons injected into the interplanetary medium. They can be routinely observed by the S/Waves instruments on-board the STEREO (Solar Terrestrial Relation Observatory) spacecraft. We describe goniopolarimetric (GP) inversion of a signal measured on non-orthogonal antennas using the Singular Value Decomposition (SVD) technique. This wave propagation analysis can be applied to spectral matrices built from measurements by the High Frequency Receiver (HFR; a part of the S/Waves experiment). We have found an empirical relation between the decomposed spectral matrices and apparent source sizes for waves with a low degree of polarization. Simulations of electromagnetic emissions with various senses and degrees of polarization, and source shapes show that SVD gives us reasonable results with respect to the polarization ellipsoid geometry. An error analysis considering inaccuracies of HFR has been performed in order to test the validity of the k-vector direction estimation and the obtained empirical relation. We present a joint observation of a type III radio burst by the STEREO and Wind spacecraft during small separation distances. We obtain consistent results for the k-vector direction and apparent source size using different analysis methods for the measurements of the STEREO and Wind spacecraft. We demonstrate that SVD can be an effective tool for the wave analysis of radio emissions measured on non-orthogonal antennas even with very extended sources.
27 citations
TL;DR: The HELIO infrastructure as discussed by the authors is a software infrastructure involving a collection of web services, heliospheric data sources (e.g., solar, planetary, etc.), and event catalogues, all of which are accessible through a unified front end.
Abstract: The Heliophysics Integrated Observatory (HELIO) is a software infrastructure involving a collection of web services, heliospheric data sources (e.g., solar, planetary, etc.), and event catalogues – all of which are accessible through a unified front end. In this paper we use the HELIO infrastructure to perform three case studies based on solar events that propagate through the heliosphere. These include a coronal mass ejection that intersects both Earth and Mars, a solar energetic particle event that crosses the orbit of Earth, and a high-speed solar wind stream, produced by a coronal hole, that is observed in situ at Earth (L1). A ballistic propagation model is run as one of the HELIO services and used to model these events, predicting if they will interact with a spacecraft or planet and determining the associated time of arrival. The HELIO infrastructure streamlines the method used to perform these kinds of case study by centralising the process of searching for and visualising data, indicating interesting features on the solar disk, and finally connecting remotely observed solar features with those detected by in situ solar wind and energetic particle instruments. HELIO represents an important leap forward in European heliophysics infrastructure by bridging the boundaries of traditional scientific domains.
15 citations
University College London1, INAF2, École Polytechnique3, University of Southampton4, Max Planck Society5, Umeå University6, Finnish Meteorological Institute7, Swedish Institute of Space Physics8, Imperial College London9, University of Oulu10, Centre national de la recherche scientifique11, Royal Institute of Technology12, University of Leicester13, University of Oslo14, University of Bergen15, Aalto University16, University of Alberta17, Jacobs University Bremen18, Lancaster University19
TL;DR: The aurorae are dynamic, luminous displays that grace the night skies of Earth's high latitude regions as discussed by the authors, but the chain of plasma physical processes leading to auroral displays is complex.
Abstract: The aurorae are dynamic, luminous displays that grace the night skies of Earth's high latitude regions. The solar wind emanating from the Sun is their ultimate energy source, but the chain of plasma physical processes leading to auroral displays is complex. The special conditions at the interface between
12 citations
TL;DR: In this article, the authors performed a statistical analysis of goniopolarimetric measurements of QP bursts made with the Radio and Plasma Wave Science investigation (RPWS) onboard Cassini spacecraft during the Jupiter flyby of 2000-2001.
Abstract: [1] Jovian quasiperiodic (QP) radio bursts are suspected to be associated with relativistic particle accelerations occurring with a quasiperiodicity between a few minutes and a few tens of minutes in Jupiter's polar magnetosphere. Understanding the excitation and propagation of QP bursts could help us to better understand this periodic energization process. A first necessary step is to measure the wave mode, source location, and directivity of QP bursts. For that purpose, we performed a statistical analysis of goniopolarimetric measurements of QP bursts made with the Radio and Plasma Wave Science investigation (RPWS) onboard Cassini spacecraft during the Jupiter flyby of 2000–2001. We studied two groups of QP bursts on 22 and 23 December 2000, and we found consistent source directions about 50 RJ north of Jupiter with an error bar ≤20 RJ. Statistics of the Stokes parameters indicate that QP bursts are partially left-handed polarized (V > 0, Q, U < 0). Together with the direction finding results, these polarization statistics imply that QP bursts observed from low latitudes are L-O mode waves which have been excited in the northern polar source, have propagated toward high latitudes, and then got refracted equatorward in the magnetosheath. Dependence of the Stokes parameters on the longitude indicates that QP bursts are excited within a particular phase range of the planetary rotation, when the system III longitude of the sub-solar point is between 260° and 480°. This implies that QP radio bursts and associated particle accelerations always occur within the same rotational sector, suggesting the existence of a recurrent magnetospheric disturbance at the planetary rotation period. Finally, we propose a possible scenario for the generation and propagation of QP bursts by combining the results of the present study with those of other recent observational and theoretical studies.