Author
Chris Paranicas
Other affiliations: University College London, Johns Hopkins University, Boston University ...read more
Bio: Chris Paranicas is an academic researcher from Johns Hopkins University Applied Physics Laboratory. The author has contributed to research in topics: Magnetosphere & Saturn. The author has an hindex of 47, co-authored 250 publications receiving 7055 citations. Previous affiliations of Chris Paranicas include University College London & Johns Hopkins University.
Papers published on a yearly basis
Papers
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TL;DR: In this article, spectral, integral moments, and composition (H, He, O, S) of energetic ions (50 keV to 50 MeV) are presented for selected Jupiter magnetospheric positions near the equator between radial distances of ∼6 to ∼46 Jupiter radii (RJ), as revealed by analysis of the Galileo Energetic Particle Detector data.
Abstract: [1] Spectra, integral moments, and composition (H, He, O, S) of energetic ions (50 keV to 50 MeV) are presented for selected Jupiter magnetospheric positions near the equator between radial distances of ∼6 to ∼46 Jupiter radii (RJ), as revealed by analysis of the Galileo Energetic Particle Detector data These characteristics are then used as the basis of interpreting and modeling reported signatures of energetic ion/neutral gas interactions within Jupiter's inner magnetosphere, particularly energetic neutral atom emissions measured during the Cassini spacecraft flyby of Jupiter Key findings include the following: (1) sulfur ions significantly dominate the energetic (≥50 keV) ion density and pressure at all radial distances >7 RJ; (2) protons dominate integral number and energy intensity planetward of 20–25 RJ; (3) a distinct signature of local, equatorial acceleration of energetic protons is revealed between Io (59 RJ) and Europa (94 RJ); (4) significant spectral and compositional signatures of neutral gas interactions are also revealed between the orbits of Io and Europa; (5) a previously reported significant depletion of ring current ion populations between Io and Europa during the early-phase operation of Galileo (∼1995), as compared with observations obtained during the Voyager epoch (1979), has persisted and probably deepened during later Galileo phases (1999); and (6) detailed energetic neutral atom emission modeling, based on the in situ results reported here, further constrains recent estimates of the contents of the neutral gas torus of Europa
200 citations
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TL;DR: In this paper, spectral, integral moments, and composition (H, He, O, S) of energetic ions (50 keV to 50 MeV) are presented for selected Jupiter magnetospheric positions near the equator between radial distances of ∼6 to ∼46 Jupiter radii (R J ), as revealed by analysis of the Galileo Energetic Particle Detector data.
Abstract: [1] Spectra, integral moments, and composition (H, He, O, S) of energetic ions (50 keV to 50 MeV) are presented for selected Jupiter magnetospheric positions near the equator between radial distances of ∼6 to ∼46 Jupiter radii (R J ), as revealed by analysis of the Galileo Energetic Particle Detector data. These characteristics are then used as the basis of interpreting and modeling reported signatures of energetic ion/neutral gas interactions within Jupiter's inner magnetosphere, particularly energetic neutral atom emissions measured during the Cassini spacecraft flyby of Jupiter. Key findings include the following: (1) sulfur ions significantly dominate the energetic (>50 keV) ion density and pressure at all radial distances >7 R J ; (2) protons dominate integral number and energy intensity planetward of 20-25 Rj; (3) a distinct signature of local, equatorial acceleration of energetic protons is revealed between Io (5.9 R J ) and Europa (9.4 R J ); (4) significant spectral and compositional signatures of neutral gas interactions are also revealed between the orbits of lo and Europa; (5) a previously reported significant depletion of ring current ion populations between Io and Europa during the early-phase operation of Galileo (∼1995), as compared with observations obtained during the Voyager epoch (1979), has persisted and probably deepened during later Galileo phases (1999); and (6) detailed energetic neutral atom emission modeling, based on the in situ results reported here, further constrains recent estimates of the contents of the neutral gas torus of Europa.
193 citations
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University of Colorado Boulder1, INAF2, University of Texas at San Antonio3, Southwest Research Institute4, University of Liège5, University of Leicester6, Goddard Space Flight Center7, Planetary Science Institute8, University of Iowa9, Jet Propulsion Laboratory10, Johns Hopkins University11, University of California, Los Angeles12, Centre national de la recherche scientifique13
TL;DR: Junior as discussed by the authors is the first spacecraft to enter polar orbit of Jupiter and venture deep into unexplored polar territories of the magnetosphere, where it carries a range of instruments that take particles and fields measurements, remote sensing observations of auroral emissions at UV, visible, IR and radio wavelengths, and detect microwave emission from Jupiter's radiation belts.
Abstract: In July 2016, NASA’s Juno mission becomes the first spacecraft to enter polar orbit of Jupiter and venture deep into unexplored polar territories of the magnetosphere. Focusing on these polar regions, we review current understanding of the structure and dynamics of the magnetosphere and summarize the outstanding issues. The Juno mission profile involves (a) a several-week approach from the dawn side of Jupiter’s magnetosphere, with an orbit-insertion maneuver on July 6, 2016; (b) a 107-day capture orbit, also on the dawn flank; and (c) a series of thirty 11-day science orbits with the spacecraft flying over Jupiter’s poles and ducking under the radiation belts. We show how Juno’s view of the magnetosphere evolves over the year of science orbits. The Juno spacecraft carries a range of instruments that take particles and fields measurements, remote sensing observations of auroral emissions at UV, visible, IR and radio wavelengths, and detect microwave emission from Jupiter’s radiation belts. We summarize how these Juno measurements address issues of auroral processes, microphysical plasma physics, ionosphere-magnetosphere and satellite-magnetosphere coupling, sources and sinks of plasma, the radiation belts, and the dynamics of the outer magnetosphere. To reach Jupiter, the Juno spacecraft passed close to the Earth on October 9, 2013, gaining the necessary energy to get to Jupiter. The Earth flyby provided an opportunity to test Juno’s instrumentation as well as take scientific data in the terrestrial magnetosphere, in conjunction with ground-based and Earth-orbiting assets.
192 citations
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TL;DR: ENA imaging has revealed a radiation belt that resides inward of the D ring and is probably the result of double charge exchange between the main radiation belt and the upper layers of Saturn's exosphere.
Abstract: The Magnetospheric Imaging Instrument (MIMI) onboard the Cassini spacecraft observed the saturnian magnetosphere from January 2004 until Saturn orbit insertion (SOI) on 1 July 2004. The MIMI sensors observed frequent energetic particle activity in interplanetary space for several months before SOI. When the imaging sensor was switched to its energetic neutral atom (ENA) operating mode on 20 February 2004, at approximately 10(3) times Saturn's radius RS (0.43 astronomical units), a weak but persistent signal was observed from the magnetosphere. About 10 days before SOI, the magnetosphere exhibited a day-night asymmetry that varied with an approximately 11-hour periodicity. Once Cassini entered the magnetosphere, in situ measurements showed high concentrations of H+, H2+, O+, OH+, and H2O+ and low concentrations of N+. The radial dependence of ion intensity profiles implies neutral gas densities sufficient to produce high loss rates of trapped ions from the middle and inner magnetosphere. ENA imaging has revealed a radiation belt that resides inward of the D ring and is probably the result of double charge exchange between the main radiation belt and the upper layers of Saturn's exosphere.
187 citations
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TL;DR: The Jupiter Energetic Particle Detector Instruments (JEDI) on the Juno Jupiter polar-orbiting, atmosphere-skimming, mission to Jupiter will coordinate with the several other space physics instruments on the NASA Juno spacecraft to characterize and understand the space environment of Jupiter's polar regions, and specifically to understand the generation of Jupiter’s powerful aurora.
Abstract: The Jupiter Energetic Particle Detector Instruments (JEDI) on the Juno Jupiter polar-orbiting, atmosphere-skimming, mission to Jupiter will coordinate with the several other space physics instruments on the Juno spacecraft to characterize and understand the space environment of Jupiter’s polar regions, and specifically to understand the generation of Jupiter’s powerful aurora. JEDI comprises 3 nearly-identical instruments and measures at minimum the energy, angle, and ion composition distributions of ions with energies from H:20 keV and O: 50 keV to >1 MeV, and the energy and angle distribution of electrons from 500 keV. Each JEDI instrument uses microchannel plates (MCP) and thin foils to measure the times of flight (TOF) of incoming ions and the pulse height associated with the interaction of ions with the foils, and it uses solid state detectors (SSD’s) to measure the total energy (E) of both the ions and the electrons. The MCP anodes and the SSD arrays are configured to determine the directions of arrivals of the incoming charged particles. The instruments also use fast triple coincidence and optimum shielding to suppress penetrating background radiation and incoming UV foreground. Here we describe the science objectives of JEDI, the science and measurement requirements, the challenges that the JEDI team had in meeting these requirements, the design and operation of the JEDI instruments, their calibrated performances, the JEDI inflight and ground operations, and the initial measurements of the JEDI instruments in interplanetary space following the Juno launch on 5 August 2011. Juno will begin its prime science operations, comprising 32 orbits with dimensions 1.1×40 RJ, in mid-2016.
173 citations
Cited by
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Space Science Institute1, Cornell University2, California Institute of Technology3, Massachusetts Institute of Technology4, Free University of Berlin5, German Aerospace Center6, University of Illinois at Urbana–Champaign7, University of Arizona8, University of Redlands9, University of Paris10, Goddard Institute for Space Studies11, Southwest Research Institute12, Queen Mary University of London13
TL;DR: Cassini has identified a geologically active province at the south pole of Saturn's moon Enceladus in images acquired by the Imaging Science Subsystem (ISS), this region is circumscribed by a chain of folded ridges and troughs at ∼55°S latitude as mentioned in this paper.
Abstract: Cassini has identified a geologically active province at the south pole of Saturn's moon Enceladus. In images acquired by the Imaging Science Subsystem (ISS), this region is circumscribed by a chain of folded ridges and troughs at ∼55°S latitude. The terrain southward of this boundary is distinguished by its albedo and color contrasts, elevated temperatures, extreme geologic youth, and narrow tectonic rifts that exhibit coarse-grained ice and coincide with the hottest temperatures measured in the region. Jets of fine icy particles that supply Saturn's E ring emanate from this province, carried aloft by water vapor probably venting from subsurface reservoirs of liquid water. The shape of Enceladus suggests a possible intense heating epoch in the past by capture into a 1:4 secondary spin/orbit resonance.
1,005 citations
01 Jan 2006
TL;DR: The shape of Enceladus suggests a possible intense heating epoch in the past by capture into a 1:4 secondary spin/orbit resonance.
859 citations
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19 Dec 2003
TL;DR: In this article, the Equations of Gas Dynamics and Magnetoplasmas Dynamics were studied, as well as Magnetoplasma Stability and Transport in Magnetplasmas and Magnetic Stability.
Abstract: 1 The Equations of Gas Dynamics 2 Magnetoplasma Dynamics 3 Waves in Magnetoplasmas 4 Magnetoplasma Stability 5 Transport in Magnetoplasmas 6 Extensions of Theory Bibliography Index
748 citations
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01 May 2011TL;DR: In this paper, the authors present an overview of the solar system and its evolution, including the formation and evolution of stars, asteroids, and free-floating planets, as well as their internal and external structures.
Abstract: 1. Introduction 2. Radial velocities 3. Astrometry 4. Timing 5. Microlensing 6. Transits 7. Imaging 8. Host stars 9. Brown dwarfs and free-floating planets 10. Formation and evolution 11. Interiors and atmospheres 12. The Solar System Appendixes References Index.
527 citations
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University of Nantes1, Imperial College London2, Paris Diderot University3, University of Leicester4, European Space Research and Technology Centre5, University College London6, University of Oxford7, Max Planck Society8, Centre national de la recherche scientifique9, Spanish National Research Council10
TL;DR: The JUpiter ICy moons Explorer (JUICE) mission as mentioned in this paper was selected by ESA in May 2012 to perform detailed investigations of Jupiter and its system in all their interrelations and complexity with particular emphasis on Ganymede as a planetary body and potential habitat.
493 citations