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Roberts JH, McKinnon WB, Elder CM, Tobie G, Biersteker JB, Young D, Park RS, Steinbrügge G, Nimmo F, Howell SM, Castillo-Rogez JC, Cable ML, Abrahams JN, Bland MT, Chivers C, Cochrane CJ, Dombard AJ, Ernst C, Genova A, Gerekos C, Glein C, Harris CD, Hay HCFC, Hayne PO, Hedman M, Hussmann H, Jia X, Khurana K, Kiefer WS, Kirk R, Kivelson M, Lawrence J, Leonard EJ, Lunine JI, Mazarico E, McCord TB, McEwen A, Paty C, Quick LC, Raymond CA, Retherford KD, Roth L, Rymer A, Saur J, Scanlan K, Schroeder DM, Senske DA, Shao W, Soderlund K, Spiers E, Styczinski MJ, Tortora P, Vance SD, Villarreal MN, Weiss BP, Westlake JH, Withers P, Wolfenbarger N, Buratti B, Korth H, Pappalardo RT. Exploring the Interior of Europa with the Europa Clipper. SPACE SCIENCE REVIEWS 2023; 219:46. [PMID: 37636325 PMCID: PMC10457249 DOI: 10.1007/s11214-023-00990-y] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/24/2022] [Accepted: 07/20/2023] [Indexed: 08/29/2023]
Abstract
The Galileo mission to Jupiter revealed that Europa is an ocean world. The Galileo magnetometer experiment in particular provided strong evidence for a salty subsurface ocean beneath the ice shell, likely in contact with the rocky core. Within the ice shell and ocean, a number of tectonic and geodynamic processes may operate today or have operated at some point in the past, including solid ice convection, diapirism, subsumption, and interstitial lake formation. The science objectives of the Europa Clipper mission include the characterization of Europa's interior; confirmation of the presence of a subsurface ocean; identification of constraints on the depth to this ocean, and on its salinity and thickness; and determination of processes of material exchange between the surface, ice shell, and ocean. Three broad categories of investigation are planned to interrogate different aspects of the subsurface structure and properties of the ice shell and ocean: magnetic induction, subsurface radar sounding, and tidal deformation. These investigations are supplemented by several auxiliary measurements. Alone, each of these investigations will reveal unique information. Together, the synergy between these investigations will expose the secrets of the Europan interior in unprecedented detail, an essential step in evaluating the habitability of this ocean world.
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Affiliation(s)
| | | | - Catherine M Elder
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, USA
| | | | | | | | - Ryan S Park
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, USA
| | - Gregor Steinbrügge
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, USA
| | - Francis Nimmo
- University of California, Santa Cruz, Santa Cruz, CA, USA
| | - Samuel M Howell
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, USA
| | | | - Morgan L Cable
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, USA
| | | | | | | | - Corey J Cochrane
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, USA
| | | | - Carolyn Ernst
- Johns Hopkins Applied Physics Laboratory, Laurel, MD, USA
| | | | | | | | | | - Hamish C F C Hay
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, USA
| | - Paul O Hayne
- University of Colorado Boulder, Boulder, CO, USA
| | | | - Hauke Hussmann
- German Aerospace Center Institute of Planetary Research, Berlin, Germany
| | | | | | - Walter S Kiefer
- Lunar and Planetary Institute, University Space Research Association, Houston, TX, USA
| | | | | | | | - Erin J Leonard
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, USA
| | | | | | | | | | | | | | - Carol A Raymond
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, USA
| | - Kurt D Retherford
- Sapienza University of Rome, Rome, Italy
- University of Texas at San Antonio, San Antonio, TX, USA
| | - Lorenz Roth
- KTH Royal Institute of Technology, Stockholm, Sweden
| | - Abigail Rymer
- Johns Hopkins Applied Physics Laboratory, Laurel, MD, USA
| | | | | | | | - David A Senske
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, USA
| | - Wencheng Shao
- University of California, Santa Cruz, Santa Cruz, CA, USA
| | | | | | - Marshall J Styczinski
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, USA
- University of Washington, Seattle, WA, USA
| | - Paolo Tortora
- Alma Mater Studiorum - Università di Bologna, Bologna, Italy
| | - Steven D Vance
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, USA
| | | | | | | | | | | | - Bonnie Buratti
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, USA
| | - Haje Korth
- Johns Hopkins Applied Physics Laboratory, Laurel, MD, USA
| | - Robert T Pappalardo
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, USA
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Fatemi S, Poppe AR, Vorburger A, Lindkvist J, Hamrin M. Ion Dynamics at the Magnetopause of Ganymede. JOURNAL OF GEOPHYSICAL RESEARCH. SPACE PHYSICS 2022; 127:e2021JA029863. [PMID: 35865030 PMCID: PMC9286830 DOI: 10.1029/2021ja029863] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/10/2021] [Revised: 12/08/2021] [Accepted: 01/04/2022] [Indexed: 06/15/2023]
Abstract
We study the dynamics of the thermal O+ and H+ ions at Ganymede's magnetopause when Ganymede is inside and outside of the Jovian plasma sheet using a three-dimensional hybrid model of plasma (kinetic ions, fluid electrons). We present the global structure of the electric fields and power density (E ⋅ J) in the magnetosphere of Ganymede and show that the power density at the magnetopause is mainly positive and on average is +0.95 and +0.75 nW/m3 when Ganymede is inside and outside the Jovian plasma sheet, respectively, but locally it reaches over +20 nW/m3. Our kinetic simulations show that ion velocity distributions at the vicinity of the upstream magnetopause of Ganymede are highly non-Maxwellian. We investigate the energization of the ions interacting with the magnetopause and find that the energy of those particles on average increases by a factor of 8 and 30 for the O+ and H+ ions, respectively. The energy of these ions is mostly within 1-100 keV for both species after interaction with the magnetopause, but a few percentages reach to 0.1-1 MeV. Our kinetic simulations show that a small fraction ( < 25%) of the corotating Jovian plasma reach the magnetopause, but among those >50% cross the high-power density regions at the magnetopause and gain energy. Finally, we compare our simulation results with Galileo observations of Ganymede's magnetopause crossings (i.e., G8 and G28 flybys). There is an excellent agreement between our simulations and observations, particularly our simulations fully capture the size and structure of the magnetosphere.
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Affiliation(s)
- S. Fatemi
- Department of PhysicsUmeå UniversityUmeåSweden
| | - A. R. Poppe
- Space Sciences LaboratoryUniversity of California at BerkeleyBerkeleyCAUSA
| | - A. Vorburger
- Department of PhysicsUmeå UniversityUmeåSweden
- Physics InstituteUniversity of BernBernSwitzerland
| | | | - M. Hamrin
- Department of PhysicsUmeå UniversityUmeåSweden
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3
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Taubner RS, Olsson-Francis K, Vance SD, Ramkissoon NK, Postberg F, de Vera JP, Antunes A, Camprubi Casas E, Sekine Y, Noack L, Barge L, Goodman J, Jebbar M, Journaux B, Karatekin Ö, Klenner F, Rabbow E, Rettberg P, Rückriemen-Bez T, Saur J, Shibuya T, Soderlund KM. Experimental and Simulation Efforts in the Astrobiological Exploration of Exooceans. SPACE SCIENCE REVIEWS 2020; 216:9. [PMID: 32025060 PMCID: PMC6977147 DOI: 10.1007/s11214-020-0635-5] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/15/2019] [Accepted: 01/06/2020] [Indexed: 05/05/2023]
Abstract
The icy satellites of Jupiter and Saturn are perhaps the most promising places in the Solar System regarding habitability. However, the potential habitable environments are hidden underneath km-thick ice shells. The discovery of Enceladus' plume by the Cassini mission has provided vital clues in our understanding of the processes occurring within the interior of exooceans. To interpret these data and to help configure instruments for future missions, controlled laboratory experiments and simulations are needed. This review aims to bring together studies and experimental designs from various scientific fields currently investigating the icy moons, including planetary sciences, chemistry, (micro-)biology, geology, glaciology, etc. This chapter provides an overview of successful in situ, in silico, and in vitro experiments, which explore different regions of interest on icy moons, i.e. a potential plume, surface, icy shell, water and brines, hydrothermal vents, and the rocky core.
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Affiliation(s)
- Ruth-Sophie Taubner
- Archaea Biology and Ecogenomics Division, University of Vienna, Vienna, Austria
| | | | | | | | | | | | - André Antunes
- State Key Laboratory of Lunar and Planetary Sciences, Macau University of Science and Technology, Macau SAR, China
| | | | | | - Lena Noack
- Freie Universität Berlin, Berlin, Germany
| | | | | | | | | | | | | | - Elke Rabbow
- German Aerospace Center (DLR), Cologne, Germany
| | | | | | | | - Takazo Shibuya
- Japan Agency for Marine-Earth Science and Technology (JAMSTEC), Yokosuka, Japan
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4
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Cohen O, Glocer A, Garraffo C, Drake JJ, Bell JM. Energy Dissipation in the Upper Atmospheres of Trappist-1 Planets. THE ASTROPHYSICAL JOURNAL. LETTERS 2018; 856:L11. [PMID: 32944211 PMCID: PMC7493050 DOI: 10.3847/2041-8213/aab5b5] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
We present a method to quantify the upper-limit of the energy transmitted from the intense stellar wind to the upper atmospheres of three of the Trappist-1 planets (e, f, and g). We use a formalism that treats the system as two electromagnetic regions, where the efficiency of the energy transmission between one region (the stellar wind at the planetary orbits) to the other (the planetary ionospheres) depends on the relation between the conductances and impedances of the two regions. Since the energy flux of the stellar wind is very high at these planetary orbits, we find that for the case of high transmission efficiency (when the conductances and impedances are close in magnitude), the energy dissipation in the upper planetary atmospheres is also very large. On average, the Ohmic energy can reach 0.5 - 1 W/m 2, about 1% of the stellar irradiance and 5-15 times the EUV irradiance. Here, using constant values for the ionospheric conductance, we demonstrate that the stellar wind energy could potentially drive large atmospheric heating in terrestrial planets, as well as in hot jupiters. More detailed calculations are needed to assess the ionospheric conductance and to determine more accurately the amount of heating the stellar wind can drive in close-orbit planets.
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Affiliation(s)
- Ofer Cohen
- Lowell Center for Space Science and Technology, University of Massachusetts Lowell 600 Suffolk St., Lowell, MA 01854, USA
- Harvard-Smithsonian Center for Astrophysics,60 Garden St., Cambridge, MA 02138, USA
| | - Alex Glocer
- NASA/Goddard Space Flight Center, Greenbelt, Maryland, USA
| | - Cecilia Garraffo
- Harvard-Smithsonian Center for Astrophysics, 60 Garden St., Cambridge, Massachusetts, USA
| | - Jeremy J Drake
- Harvard-Smithsonian Center for Astrophysics, 60 Garden St., Cambridge, Massachusetts, USA
| | - Jared M Bell
- National Institute of Aerospace, 100 Exploration Way, Hampton, VA 23666, USA
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5
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Desai RT, Cowee MM, Wei H, Fu X, Gary SP, Volwerk M, Coates AJ. Hybrid Simulations of Positively and Negatively Charged Pickup Ions and Cyclotron Wave Generation at Europa. JOURNAL OF GEOPHYSICAL RESEARCH. SPACE PHYSICS 2017; 122:10408-10420. [PMID: 29263979 PMCID: PMC5726379 DOI: 10.1002/2017ja024479] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/16/2017] [Revised: 08/17/2017] [Accepted: 09/13/2017] [Indexed: 06/07/2023]
Abstract
In the vicinity of Europa, Galileo observed bursty Alfvén-cyclotron wave power at the gyrofrequencies of a number of species including K+, O 2+, Na+, and Cl+, indicating the localized pickup of these species. Additional evidence for the presence of chlorine was the occurrence of both left-hand (LH) and right-hand (RH) polarized transverse wave power near the Cl+ gyrofrequency, thought to be due to the pickup of both Cl+ and the easily formed chlorine anion, Cl-. To test this hypothesis, we use one-dimensional hybrid (kinetic ion, massless fluid electron) simulations for both positive and negative pickup ions and self-consistently reproduce the growth of both LH and RH Alfvén-cyclotron waves in agreement with linear theory. We show how the simultaneous generation of LH and RH waves can result in nongyrotropic ion distributions and increased wave amplitudes, and how even trace quantities of negative pickup ions are able to generate an observable RH signal. Through comparing simulated and observed wave amplitudes, we are able to place the first constraints on the densities of Chlorine pickup ions in localized regions at Europa.
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Affiliation(s)
- R. T. Desai
- Mullard Space Science LaboratoryUniversity College LondonLondonUK
- Centre for Planetary SciencesUniversity College London/BirkbeckLondonUK
| | - M. M. Cowee
- Los Alamos National LaboratoryLos AlamosNMUSA
| | - H. Wei
- Institute of Geophysics and Planetary PhysicsUniversity of CaliforniaLos AngelesCAUSA
| | - X. Fu
- Space Science InstituteBoulderCOUSA
| | - S. P. Gary
- Los Alamos National LaboratoryLos AlamosNMUSA
- Space Science InstituteBoulderCOUSA
| | - M. Volwerk
- Space Research InstituteAustrian Academy of SciencesGrazAustria
| | - A. J. Coates
- Mullard Space Science LaboratoryUniversity College LondonLondonUK
- Centre for Planetary SciencesUniversity College London/BirkbeckLondonUK
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6
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Cohen O, Ma Y, Drake JJ, Glocer A, Garraffo C, Bell JM, Gombosi TI. THE INTERACTION OF VENUS-LIKE, M-DWARF PLANETS WITH THE STELLAR WIND OF THEIR HOST STAR. ACTA ACUST UNITED AC 2015. [DOI: 10.1088/0004-637x/806/1/41] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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7
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Teolis BD, Sillanpää I, Waite JH, Khurana KK. Surface current balance and thermoelectric whistler wings at airless astrophysical bodies: Cassini at Rhea. JOURNAL OF GEOPHYSICAL RESEARCH. SPACE PHYSICS 2014; 119:8881-8901. [PMID: 26167436 PMCID: PMC4497460 DOI: 10.1002/2014ja020094] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/18/2014] [Revised: 10/02/2014] [Accepted: 10/04/2014] [Indexed: 06/04/2023]
Abstract
UNLABELLED Sharp magnetic perturbations found by the Cassini spacecraft at the edge of the Rhea flux tube are consistent with field-aligned flux tube currents. The current system results from the difference of ion and electron gyroradii and the requirement to balance currents on the sharp Rhea surface. Differential-type hybrid codes that solve for ion velocity and magnetic field have an intrinsic difficulty modeling the plasma absorber's sharp surface. We overcome this problem by instead using integral equations to solve for ion and electron currents and obtain agreement with the magnetic perturbations at Rhea's flux tube edge. An analysis of the plasma dispersion relations and Cassini data reveals that field-guided whistler waves initiated by (1) the electron velocity anisotropy in the flux tube and (2) interaction with surface sheath electrostatic waves on topographic scales may facilitate propagation of the current system to large distances from Rhea. Current systems like those at Rhea should occur generally, for plasma absorbers of any size such as spacecraft or planetary bodies, in a wide range of space plasma environments. Motion through the plasma is not essential since the current system is thermodynamic in origin, excited by heat flow into the object. The requirements are a difference of ion and electron gyroradii and a sharp surface, i.e., without a significant thick atmosphere. KEY POINTS Surface current balance condition yields a current system at astronomical bodiesCurrent system possible for sharp (airless) objects of any sizeCurrent system is thermoelectric and motion through the plasma nonessential.
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Affiliation(s)
- B D Teolis
- Space Science Division, Southwest Research Institute San Antonio, Texas, USA
| | - I Sillanpää
- Space Science Division, Southwest Research Institute San Antonio, Texas, USA
| | - J H Waite
- Space Science Division, Southwest Research Institute San Antonio, Texas, USA
| | - K K Khurana
- Institute of Geophysics and Planetary Physics, University of California Los Angeles, California, USA
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8
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Khurana KK, Jia X, Kivelson MG, Nimmo F, Schubert G, Russell CT. Evidence of a global magma ocean in Io's interior. Science 2011; 332:1186-9. [PMID: 21566160 DOI: 10.1126/science.1201425] [Citation(s) in RCA: 94] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Extensive volcanism and high-temperature lavas hint at a global magma reservoir in Io, but no direct evidence has been available. We exploited Jupiter's rotating magnetic field as a sounding signal and show that the magnetometer data collected by the Galileo spacecraft near Io provide evidence of electromagnetic induction from a global conducting layer. We demonstrate that a completely solid mantle provides insufficient response to explain the magnetometer observations, but a global subsurface magma layer with a thickness of over 50 kilometers and a rock melt fraction of 20% or more is fully consistent with the observations. We also place a stronger upper limit of about 110 nanoteslas (surface equatorial field) on the dynamo dipolar field generated inside Io.
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Affiliation(s)
- Krishan K Khurana
- Institute of Geophysics and Planetary Physics, University of California at Los Angeles, Los Angeles, CA 90095, USA.
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9
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Simon S, Saur J, Kriegel H, Neubauer FM, Motschmann U, Dougherty MK. Influence of negatively charged plume grains and hemisphere coupling currents on the structure of Enceladus' Alfvén wings: Analytical modeling of Cassini magnetometer observations. ACTA ACUST UNITED AC 2011. [DOI: 10.1029/2010ja016338] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Sven Simon
- Institute of Geophysics and Meteorology; University of Cologne; Cologne Germany
| | - Joachim Saur
- Institute of Geophysics and Meteorology; University of Cologne; Cologne Germany
| | - Hendrik Kriegel
- Institute for Theoretical Physics; Technische Universität Braunschweig; Braunschweig Germany
| | - Fritz M. Neubauer
- Institute of Geophysics and Meteorology; University of Cologne; Cologne Germany
| | - Uwe Motschmann
- Institute for Theoretical Physics; Technische Universität Braunschweig; Braunschweig Germany
- Institute for Planetary Research; German Aerospace Center; Berlin Germany
| | - Michele K. Dougherty
- Space and Atmospheric Physics Group, Blackett Laboratory; Imperial College London; London UK
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10
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Wei HY, Russell CT, Dougherty MK, Neubauer FM, Ma YJ. Upper limits on Titan's magnetic moment and implications for its interior. ACTA ACUST UNITED AC 2010. [DOI: 10.1029/2009je003538] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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11
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Schilling N, Neubauer FM, Saur J. Influence of the internally induced magnetic field on the plasma interaction of Europa. ACTA ACUST UNITED AC 2008. [DOI: 10.1029/2007ja012842] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- N. Schilling
- Institut für Geophysik und Meteorologie; Universität zu Köln; Cologne Germany
| | - F. M. Neubauer
- Institut für Geophysik und Meteorologie; Universität zu Köln; Cologne Germany
| | - J. Saur
- Institut für Geophysik und Meteorologie; Universität zu Köln; Cologne Germany
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12
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Saur J, Neubauer FM, Schilling N. Hemisphere coupling in Enceladus' asymmetric plasma interaction. ACTA ACUST UNITED AC 2007. [DOI: 10.1029/2007ja012479] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Joachim Saur
- Institut für Geophysik und Meteorologie; Universität zu Köln; Cologne Germany
| | - Fritz M. Neubauer
- Institut für Geophysik und Meteorologie; Universität zu Köln; Cologne Germany
| | - Nico Schilling
- Institut für Geophysik und Meteorologie; Universität zu Köln; Cologne Germany
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13
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Retherford KD, Spencer JR, Stern SA, Saur J, Strobel DF, Steffl AJ, Gladstone GR, Weaver HA, Cheng AF, Parker JW, Slater DC, Versteeg MH, Davis MW, Bagenal F, Throop HB, Lopes RMC, Reuter DC, Lunsford A, Conard SJ, Young LA, Moore JM. Io's Atmospheric Response to Eclipse: UV Aurorae Observations. Science 2007; 318:237-40. [DOI: 10.1126/science.1147594] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Affiliation(s)
- K. D. Retherford
- Southwest Research Institute, San Antonio, TX 78228, USA
- Southwest Research Institute, Boulder, CO 80302, USA
- NASA Headquarters, Washington, DC 20546, USA
- University of Cologne, 50923 Koln, Germany
- The Johns Hopkins University, Baltimore, MD 21218, USA
| | - J. R. Spencer
- Southwest Research Institute, San Antonio, TX 78228, USA
- Southwest Research Institute, Boulder, CO 80302, USA
- NASA Headquarters, Washington, DC 20546, USA
- University of Cologne, 50923 Koln, Germany
- The Johns Hopkins University, Baltimore, MD 21218, USA
| | - S. A. Stern
- Southwest Research Institute, San Antonio, TX 78228, USA
- Southwest Research Institute, Boulder, CO 80302, USA
- NASA Headquarters, Washington, DC 20546, USA
- University of Cologne, 50923 Koln, Germany
- The Johns Hopkins University, Baltimore, MD 21218, USA
| | - J. Saur
- Southwest Research Institute, San Antonio, TX 78228, USA
- Southwest Research Institute, Boulder, CO 80302, USA
- NASA Headquarters, Washington, DC 20546, USA
- University of Cologne, 50923 Koln, Germany
- The Johns Hopkins University, Baltimore, MD 21218, USA
| | - D. F. Strobel
- Southwest Research Institute, San Antonio, TX 78228, USA
- Southwest Research Institute, Boulder, CO 80302, USA
- NASA Headquarters, Washington, DC 20546, USA
- University of Cologne, 50923 Koln, Germany
- The Johns Hopkins University, Baltimore, MD 21218, USA
| | - A. J. Steffl
- Southwest Research Institute, San Antonio, TX 78228, USA
- Southwest Research Institute, Boulder, CO 80302, USA
- NASA Headquarters, Washington, DC 20546, USA
- University of Cologne, 50923 Koln, Germany
- The Johns Hopkins University, Baltimore, MD 21218, USA
| | - G. R. Gladstone
- Southwest Research Institute, San Antonio, TX 78228, USA
- Southwest Research Institute, Boulder, CO 80302, USA
- NASA Headquarters, Washington, DC 20546, USA
- University of Cologne, 50923 Koln, Germany
- The Johns Hopkins University, Baltimore, MD 21218, USA
| | - H. A. Weaver
- Southwest Research Institute, San Antonio, TX 78228, USA
- Southwest Research Institute, Boulder, CO 80302, USA
- NASA Headquarters, Washington, DC 20546, USA
- University of Cologne, 50923 Koln, Germany
- The Johns Hopkins University, Baltimore, MD 21218, USA
| | - A. F. Cheng
- Southwest Research Institute, San Antonio, TX 78228, USA
- Southwest Research Institute, Boulder, CO 80302, USA
- NASA Headquarters, Washington, DC 20546, USA
- University of Cologne, 50923 Koln, Germany
- The Johns Hopkins University, Baltimore, MD 21218, USA
| | - J. Wm. Parker
- Southwest Research Institute, San Antonio, TX 78228, USA
- Southwest Research Institute, Boulder, CO 80302, USA
- NASA Headquarters, Washington, DC 20546, USA
- University of Cologne, 50923 Koln, Germany
- The Johns Hopkins University, Baltimore, MD 21218, USA
| | - D. C. Slater
- Southwest Research Institute, San Antonio, TX 78228, USA
- Southwest Research Institute, Boulder, CO 80302, USA
- NASA Headquarters, Washington, DC 20546, USA
- University of Cologne, 50923 Koln, Germany
- The Johns Hopkins University, Baltimore, MD 21218, USA
| | - M. H. Versteeg
- Southwest Research Institute, San Antonio, TX 78228, USA
- Southwest Research Institute, Boulder, CO 80302, USA
- NASA Headquarters, Washington, DC 20546, USA
- University of Cologne, 50923 Koln, Germany
- The Johns Hopkins University, Baltimore, MD 21218, USA
| | - M. W. Davis
- Southwest Research Institute, San Antonio, TX 78228, USA
- Southwest Research Institute, Boulder, CO 80302, USA
- NASA Headquarters, Washington, DC 20546, USA
- University of Cologne, 50923 Koln, Germany
- The Johns Hopkins University, Baltimore, MD 21218, USA
| | - F. Bagenal
- Southwest Research Institute, San Antonio, TX 78228, USA
- Southwest Research Institute, Boulder, CO 80302, USA
- NASA Headquarters, Washington, DC 20546, USA
- University of Cologne, 50923 Koln, Germany
- The Johns Hopkins University, Baltimore, MD 21218, USA
| | - H. B. Throop
- Southwest Research Institute, San Antonio, TX 78228, USA
- Southwest Research Institute, Boulder, CO 80302, USA
- NASA Headquarters, Washington, DC 20546, USA
- University of Cologne, 50923 Koln, Germany
- The Johns Hopkins University, Baltimore, MD 21218, USA
| | - R. M. C. Lopes
- Southwest Research Institute, San Antonio, TX 78228, USA
- Southwest Research Institute, Boulder, CO 80302, USA
- NASA Headquarters, Washington, DC 20546, USA
- University of Cologne, 50923 Koln, Germany
- The Johns Hopkins University, Baltimore, MD 21218, USA
| | - D. C. Reuter
- Southwest Research Institute, San Antonio, TX 78228, USA
- Southwest Research Institute, Boulder, CO 80302, USA
- NASA Headquarters, Washington, DC 20546, USA
- University of Cologne, 50923 Koln, Germany
- The Johns Hopkins University, Baltimore, MD 21218, USA
| | - A. Lunsford
- Southwest Research Institute, San Antonio, TX 78228, USA
- Southwest Research Institute, Boulder, CO 80302, USA
- NASA Headquarters, Washington, DC 20546, USA
- University of Cologne, 50923 Koln, Germany
- The Johns Hopkins University, Baltimore, MD 21218, USA
| | - S. J. Conard
- Southwest Research Institute, San Antonio, TX 78228, USA
- Southwest Research Institute, Boulder, CO 80302, USA
- NASA Headquarters, Washington, DC 20546, USA
- University of Cologne, 50923 Koln, Germany
- The Johns Hopkins University, Baltimore, MD 21218, USA
| | - L. A. Young
- Southwest Research Institute, San Antonio, TX 78228, USA
- Southwest Research Institute, Boulder, CO 80302, USA
- NASA Headquarters, Washington, DC 20546, USA
- University of Cologne, 50923 Koln, Germany
- The Johns Hopkins University, Baltimore, MD 21218, USA
| | - J. M. Moore
- Southwest Research Institute, San Antonio, TX 78228, USA
- Southwest Research Institute, Boulder, CO 80302, USA
- NASA Headquarters, Washington, DC 20546, USA
- University of Cologne, 50923 Koln, Germany
- The Johns Hopkins University, Baltimore, MD 21218, USA
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14
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Neubauer FM, Backes H, Dougherty MK, Wennmacher A, Russell CT, Coates A, Young D, Achilleos N, André N, Arridge CS, Bertucci C, Jones GH, Khurana KK, Knetter T, Law A, Lewis GR, Saur J. Titan's near magnetotail from magnetic field and electron plasma observations and modeling: Cassini flybys TA, TB, and T3. ACTA ACUST UNITED AC 2006. [DOI: 10.1029/2006ja011676] [Citation(s) in RCA: 77] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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15
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16
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Saur J. A model of Io's local electric field for a combined Alfvénic and unipolar inductor far-field coupling. ACTA ACUST UNITED AC 2004. [DOI: 10.1029/2002ja009354] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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17
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18
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Saur J, Neubauer FM, Strobel DF, Summers ME. Interpretation of Galileo's Io plasma and field observations: I0, I24, and I27 flybys and close polar passes. ACTA ACUST UNITED AC 2002. [DOI: 10.1029/2001ja005067] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Joachim Saur
- Institut für Geophysik u. Meteorologie; Universität zu Köln, Albertus Magnus Platz; Cologne Germany
| | - Fritz M. Neubauer
- Institut für Geophysik u. Meteorologie; Universität zu Köln, Albertus Magnus Platz; Cologne Germany
| | - Darrell F. Strobel
- Departments of Earth and Planetary Sciences and Physics and Astronomy; Johns Hopkins University; Baltimore Maryland USA
| | - Michael E. Summers
- School of Computational Sciences and Department of Physics and Astronomy; George Mason University; Fairfax Virginia USA
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19
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Kivelson MG, Khurana KK, Russell CT, Joy SP, Volwerk M, Walker RJ, Zimmer C, Linker JA. Magnetized or unmagnetized: Ambiguity persists following Galileo's encounters with Io in 1999 and 2000. ACTA ACUST UNITED AC 2001. [DOI: 10.1029/2000ja002510] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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20
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Kivelson MG, Khurana KK, Russell CT, Volwerk M, Walker RJ, Zimmer C. Galileo magnetometer measurements: a stronger case for a subsurface ocean at Europa. Science 2000; 289:1340-3. [PMID: 10958778 DOI: 10.1126/science.289.5483.1340] [Citation(s) in RCA: 107] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
On 3 January 2000, the Galileo spacecraft passed close to Europa when it was located far south of Jupiter's magnetic equator in a region where the radial component of the magnetospheric magnetic field points inward toward Jupiter. This pass with a previously unexamined orientation of the external forcing field distinguished between an induced and a permanent magnetic dipole moment model of Europa's internal field. The Galileo magnetometer measured changes in the magnetic field predicted if a current-carrying outer shell, such as a planet-scale liquid ocean, is present beneath the icy surface. The evidence that Europa's field varies temporally strengthens the argument that a liquid ocean exists beneath the present-day surface.
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Affiliation(s)
- M G Kivelson
- Institute of Geophysics and Planetary Physics, University of California, Los Angeles, CA 90095-1567, USA.
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21
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Kabin K, Israelevich RL, Ershkovich AI, Neubauer FM, Gombosi TI, De Zeeuw DL, Powell KG. Titan's magnetic wake: Atmospheric or magnetospheric interaction. ACTA ACUST UNITED AC 2000. [DOI: 10.1029/2000ja900012] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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22
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Glassmeier KH. Currents in Mercury's magnetosphere. MAGNETOSPHERIC CURRENT SYSTEMS 2000. [DOI: 10.1029/gm118p0371] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
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23
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Neubauer FM. Alfvén wings and electromagnetic induction in the interiors: Europa and Callisto. ACTA ACUST UNITED AC 1999. [DOI: 10.1029/1999ja900217] [Citation(s) in RCA: 59] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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24
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Saur J, Neubauer FM, Strobel DF, Summers ME. Three-dimensional plasma simulation of Io's interaction with the Io plasma torus: Asymmetric plasma flow. ACTA ACUST UNITED AC 1999. [DOI: 10.1029/1999ja900304] [Citation(s) in RCA: 107] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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25
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Abstract
NASA's Galileo mission to Jupiter and improved Earth-based observing capabilities have allowed major advances in our understanding of Jupiter's moons Io, Europa, Ganymede, and Callisto over the past few years. Particularly exciting findings include the evidence for internal liquid water oceans in Callisto and Europa, detection of a strong intrinsic magnetic field within Ganymede, discovery of high-temperature silicate volcanism on Io, discovery of tenuous oxygen atmospheres at Europa and Ganymede and a tenuous carbon dioxide atmosphere at Callisto, and detection of condensed oxygen on Ganymede. Modeling of landforms seen at resolutions up to 100 times as high as those of Voyager supports the suggestion that tidal heating has played an important role for Io and Europa.
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Affiliation(s)
- A P Showman
- Department of Mechanical Engineering, University of Louisville, 215 Sackett Hall, Louisville, KY 40292, USA
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26
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Kabin K, Combi MR, Gombosi TI, Nagy AF, DeZeeuw DL, Powell KG. On Europa's magnetospheric interaction: A MHD simulation of the E4 flyby. ACTA ACUST UNITED AC 1999. [DOI: 10.1029/1999ja900263] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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27
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Kivelson MG, Khurana KK, Stevenson DJ, Bennett L, Joy S, Russell CT, Walker RJ, Zimmer C, Polanskey C. Europa and Callisto: Induced or intrinsic fields in a periodically varying plasma environment. ACTA ACUST UNITED AC 1999. [DOI: 10.1029/1998ja900095] [Citation(s) in RCA: 153] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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28
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Khurana KK, Kivelson MG, Stevenson DJ, Schubert G, Russell CT, Walker RJ, Polanskey C. Induced magnetic fields as evidence for subsurface oceans in Europa and Callisto. Nature 1998; 395:777-80. [PMID: 9796812 DOI: 10.1038/27394] [Citation(s) in RCA: 76] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The Galileo spacecraft has been orbiting Jupiter since 7 December 1995, and encounters one of the four galilean satellites-Io, Europa, Ganymede and Callisto-on each orbit. Initial results from the spacecraft's magnetometer have indicated that neither Europa nor Callisto have an appreciable internal magnetic field, in contrast to Ganymede and possibly Io. Here we report perturbations of the external magnetic fields (associated with Jupiter's inner magnetosphere) in the vicinity of both Europa and Callisto. We interpret these perturbations as arising from induced magnetic fields, generated by the moons in response to the periodically varying plasma environment. Electromagnetic induction requires eddy currents to flow within the moons, and our calculations show that the most probable explanation is that there are layers of significant electrical conductivity just beneath the surfaces of both moons. We argue that these conducting layers may best be explained by the presence of salty liquid-water oceans, for which there is already indirect geological evidence in the case of Europa.
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Affiliation(s)
- K K Khurana
- Institute of Geophysics and Planetary Physics, University of California, Los Angeles 90095, USA.
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29
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Saur J, Strobel DF, Neubauer FM. Interaction of the Jovian magnetosphere with Europa: Constraints on the neutral atmosphere. ACTA ACUST UNITED AC 1998. [DOI: 10.1029/97je03556] [Citation(s) in RCA: 144] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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30
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