References of "Grodent, Denis"
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See detailEvidence for Auroral Emissions from Callisto's Footprint in HST UV Images
Bhattacharyya, Dolon; Clarke, John T.; Montgomery, Jordan et al

in Journal of Geophysical Research. Space Physics (in press)

Auroral emissions are expected from the footprint of Callisto in Jupiter's upper atmosphere owing to the known interaction of its atmosphere with Jupiter's magnetosphere, and from the observed auroral ... [more ▼]

Auroral emissions are expected from the footprint of Callisto in Jupiter's upper atmosphere owing to the known interaction of its atmosphere with Jupiter's magnetosphere, and from the observed auroral emissions from the footprints of the other three Galilean satellites. The mapping of Callisto along modeled magnetic field lines at Jupiter, however, places the expected footprint at the same latitude as the main auroral emissions, making it difficult to detect. We analyzed ultraviolet images of Jupiter taken using the HST/ACS instrument during a large observing campaign in 2007. Using a co-addition method similar to one used for Enceladus, we have identified a strong candidate for the footprint of Callisto on May 24, 2007. We tested this finding by applying the same co-addition technique to a nearly identical auroral configuration on May 30, 2007 when Callisto was behind Jupiter, not visible from Earth (CML = 22°; sub-Callisto system III longitude = 327°). By comparing the two co-added images, we can clearly see the presence of a strongly sub-corotating spot close to the expected Callisto footprint location on 24th May and its absence on 30th May. On the 24th Callisto was located in the current sheet. We also found a probable candidate on 26th May 2007 during which time Callisto was positioned below the current sheet. The measured location and intensity of the auroral emission provides important information about the interaction of Callisto with Jupiter's magnetic field, the corotating plasma, and the neutral and ionized state of the thin atmosphere of Callisto. [less ▲]

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See detailJuno-UVS observation of the Io footprint: Influence of Io’s local environment and passage into eclipse on the strength of the interaction
Hue, Vincent; Gladstone, Randy; Greathouse, Thomas K et al

Poster (2017, December 13)

The Juno mission offers an unprecedented opportunity to study Jupiter, from its internal structure to its magnetospheric environment. Juno-UVS is a UV spectrograph with a bandpass of 70<λ<205 nm, built to ... [more ▼]

The Juno mission offers an unprecedented opportunity to study Jupiter, from its internal structure to its magnetospheric environment. Juno-UVS is a UV spectrograph with a bandpass of 70<λ<205 nm, built to characterize Jupiter’s UV emissions and provide remote sensing capacities for the onboard fields and particle instruments (MAG, Waves, JADE and JEDI). Juno’s orbit allows observing Jupiter from a unique vantage point above the poles. In particular, UVS has observed the instantaneous Io footprint and extended tail as Io enters into eclipse. This observation may better constrain whether the atmosphere of Io is sustained via volcanic activity or sublimation. Among other processes, the modulation of Io’s footprint brightness correlates to the strength of the interaction between the Io plasma torus and its ionosphere, which, in turn, is likely to be affected by the atmospheric collapse. UVS observed the Io footprint during two eclipses that occurred on PJ1 and PJ3, and one additional eclipse observation is planned during PJ9 (24 Oct. 2017). We present how the electrodynamic coupling between Io and Jupiter is influenced by changes in Io’s local environment, e.g. Io’s passage in and out of eclipse and Io’s traverse of the magnetodisc plasma sheet. [less ▲]

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See detailSystematic capture of MeV electron beams by MWR
Santos-Costa, Daniel; Bellotti, Amadeo; Janssen, Mike et al

Poster (2017, December 13)

Every ~ 53 days since August 2016, Juno swings by Jupiter and as the spacecraft spins along a polar orbit, measurements of Jupiter's microwave radiation are carried out at high data rates for several ... [more ▼]

Every ~ 53 days since August 2016, Juno swings by Jupiter and as the spacecraft spins along a polar orbit, measurements of Jupiter's microwave radiation are carried out at high data rates for several hours (~ 9 hours) with the Juno Microwave Radiometer (MWR). Within ~ 6 planetary radii (Rj) and from inside/outside the magnetospheric region, the thermal and synchrotron emissions are measured at high temporal and spatial resolutions. In this paper, we present a synthesis of the spatial distributions of the microwave radiation and discuss the similarities and differences observed at six wavelengths (1.3-50 cm). In addition to the thermal emission and synchrotron radiation from Jupiter's electron belt, unexpected signatures in MWR are either systematically or sporadically reported during perijove 1 (PJ1) and PJ3-PJ6. The preliminary results of a multi-instrument analysis of radio (MWR), extreme and far-ultraviolet auroral emissions (Juno UVS), field (Juno magnetometer), keV electrons (JEDI), and background radiation signatures in Juno's ASC and SRU instruments suggest that some of these signatures are consistent with the capture by MWR of synchrotron emission radiated by MeV electron beams, which may be associated with auroral activity. We subsequently describe in detail our data analysis and effort to model the synchrotron radiation from MeV electron beams to support our findings. [less ▲]

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See detailOverview of HST observa7ons of Jupiter’s ultraviolet aurora during Juno orbits 3 to 7
Grodent, Denis ULiege; Bonfond, Bertrand ULiege; Yao, Zhonghua ULiege et al

Conference (2017, December 12)

Jupiter’s permanent ultraviolet auroral emissions have been systematically monitored from Earth orbit with the Hubble Space Telescope (HST) during an 8-month period. The Girst part of this HST large ... [more ▼]

Jupiter’s permanent ultraviolet auroral emissions have been systematically monitored from Earth orbit with the Hubble Space Telescope (HST) during an 8-month period. The Girst part of this HST large program (GO-14634) was meant to support the NASA Juno prime mission during orbits PJ03 through PJ07. The HST program will resume in Feb 2018, in time for Juno’s PJ11 perijove, right after HST’s solar and lunar avoidance periods. HST observations are designed to provide a Jovian auroral activity background for all instruments on-board Juno and for the numerous ground based and space based observatories participating to the Juno mission. In particular, several HST visits were programmed in order to obtain as many simultaneous observations with Juno-UVS as possible, sometimes in the same hemisphere, sometimes in the opposite one. In addition, the timing of some HST visits was set to take advantage of Juno’s multiple crossings of the current sheet and of the magnetic Gield lines threading the auroral emissions. These observations are obtained with the Space Telescope Imaging Spectrograph (STIS) in time-tag mode, they consist in spatially resolved movies of Jupiter’s highly dynamic aurora with timescales ranging from seconds to several days. Here, we present an overview of the present -numerous- HST results. They demonstrate that while Jupiter is always showing the same basic auroral components, it is also displaying an ever-changing auroral landscape. The complexity of the auroral morphology is such that no two observations are alike. Still, in this apparent chaos some patterns emerge. This information is giving clues on magnetospheric processes at play at the local and global scales, the latter being only accessible to remote sensing instruments such as HST. [less ▲]

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See detailA comparative examination of auroral acceleration processes at Jupiter and Earth as enabled by the Juno mission to Jupiter
Mauk, Barry; Haggerty, Dennis; Paranicas, Chris et al

Conference (2017, December 12)

Particle distributions observed by Juno’s Energetic Particle Detector Investigation (JEDI) at low altitudes over Jupiter’s polar regions are exceedingly diverse in directionality and in the shapes of ... [more ▼]

Particle distributions observed by Juno’s Energetic Particle Detector Investigation (JEDI) at low altitudes over Jupiter’s polar regions are exceedingly diverse in directionality and in the shapes of their 3-dimensional energy distributions. Asymmetric, bi-directional angular beams with broad energy distributions are often observed near Jupiter’s main auroral oval with considerable variability as to whether upward or downward intensities are the strongest. Signatures of upward and downward magnetic field-aligned potentials, with inferred potentials up to 100’s of kV are sometimes observed, but unlike at Earth, these potentials do not seem to be associated with the strongest discrete-like auroral emission intensities. Particle distributions have similarities to those observed at Earth over the various phenomenological auroral emission regions, but they are observed in unexpected places with respect to the strongest auroral emission regions, and the jovian distributions are much more energetic. We present a comparative examination of auroral acceleration processes observed at Earth and Jupiter in relation to the respective auroral emission regions. [less ▲]

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See detailAn overview of the first year of observations of Jupiter’s auroras by Juno-UVS with multi-wavelength comparisons
Gladstone, Randy; Greathouse, Thomas K; Versteeg, Maarten H et al

Conference (2017, December 12)

Juno’s Ultraviolet Spectrograph (Juno-UVS) has observed the Jovian aurora during eight perijove passes. UVS typically observes Jupiter for 10 hours centered on closest approach in a series of swaths, with ... [more ▼]

Juno’s Ultraviolet Spectrograph (Juno-UVS) has observed the Jovian aurora during eight perijove passes. UVS typically observes Jupiter for 10 hours centered on closest approach in a series of swaths, with one swath per Juno spin (~30s). During this period the spacecraft range to Jupiter’s aurora decreases from ~6 RJ to ~0.3 RJ (or less) in the north, and then reverses this in the south, so that spatial resolution changes dramatically. A scan mirror is used to target different features or raster across the entire auroral region. Juno-UVS observes a particular location for roughly 17 ms/swath, so the series of swaths provide snapshots of ultraviolet auroral brightness and color. A variety of forms and activity levels are represented in the Juno-UVS data–some have been described before with HST observations, but others are new. One interesting result is that the color ratio, often used as a proxy for energetic particle precipitation, may instead (in certain regions) indicate excitation of H2 by low-energy ionospheric electrons. Additional results from comparisons with simultaneous observations at x-ray, visible, and near-IR wavelengths will also be presented. [less ▲]

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See detailTransient brightening of Jupiter's aurora observed by the Hisaki satellite and Hubble Space Telescope during approach phase of the Juno spacecraft (Invited)
Kimura, Tomoki; Nichols, Jonathan D.; Gray, Rebecca et al

Conference (2017, December 12)

In early 2014, continuous monitoring with the Hisaki satellite discovered transient auroral emission at Jupiter during a period when the solar wind was relatively quiet for a few days. Simultaneous ... [more ▼]

In early 2014, continuous monitoring with the Hisaki satellite discovered transient auroral emission at Jupiter during a period when the solar wind was relatively quiet for a few days. Simultaneous imaging made by the Hubble Space Telescope (HST) suggested that the transient aurora is associated with a global magnetospheric disturbance that spans from the inner to outer magnetosphere. However, the temporal and spatial evolutions of the magnetospheric disturbance were not resolved because of the lack of continuous monitoring of the transient aurora simultaneously with the imaging. Here we report the coordinated observation of the aurora and plasma torus made by Hisaki and HST during the approach phase of the Juno spacecraft in mid-2016. On day 142, Hisaki detected a transient aurora with a maximum total H2 emission power of ~8.5 TW. The simultaneous HST imaging was indicative of a large ‘dawn storm’, which is associated with tail reconnection, at the onset of the transient aurora. The outer emission, which is associated with hot plasma injection in the inner magnetosphere, followed the dawn storm within less than two Jupiter rotations. The monitoring of the torus with Hisaki indicated that the hot plasma population increased in the torus during the transient aurora. These results imply that the magnetospheric disturbance is initiated via the tail reconnection and rapidly expands toward the inner magnetosphere, followed by the hot plasma injection reaching the plasma torus. This corresponds to the radially inward transport of the plasma and/or energy from the outer to the inner magnetosphere. https://doi.org/10.1002/2017GL072912 [less ▲]

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See detailProbing Jupiter’s auroral radio sources with Juno
Imai, M.; Kurth, W. S.; Hospodarsky, G. B. et al

Conference (2017, December 12)

Jupiter is the major auroral radio source in our solar system, producing Jovian low-frequency radio emissions in a broad frequency range of 10 kHz to 40 MHz from both north and south polar regions of the ... [more ▼]

Jupiter is the major auroral radio source in our solar system, producing Jovian low-frequency radio emissions in a broad frequency range of 10 kHz to 40 MHz from both north and south polar regions of the planet. These sporadic nonthermal bursts have been monitored with the radio and plasma wave instrument (Waves) aboard the spinning Juno spacecraft in polar orbit about Jupiter since July 5, 2016. The Waves instrument is composed of one electric dipole antenna, one magnetic search coil sensor, and three on-board receivers that record the electric fields of waves from 50 Hz to 41 MHz and the magnetic fields of waves from 50 Hz to 20 kHz. Juno has three advantageous methods to determine the radio source locations and the beaming properties for the Jovian low-frequency radio emissions: (1) identifying emission frequency close to the local gyrofrequency at the source with in situ particle measurements through Juno's perijove surveys from pole to pole, (2) the spin-modulated spectral density recorded with Juno Waves to estimate the direction of arrival of incoming waves, and (3) with the aid of the Jovian radio beaming model, performing stereoscopic radio observations with Juno, Cassini, STEREO A, WIND, and Earth-based radio telescopes (e.g., LWA1 in New Mexico, USA, and NDA in Nançay, France) or investigating the statistical characteristics of Jovian radio occurrence by Juno. Because the three individual methods are self-consistent and complement each other, Juno observations are useful for determining the Jovian radio beam parameters and radio source locations, which can be traced along magnetic field lines onto Jupiter's atmosphere and further compared with the UV aurora taken by the Hubble Space Telescope. In this talk, we give a brief overview of early radio astronomy results from Juno, providing the recent results from these extended studies by means of the three methods. [less ▲]

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See detailFirst simultaneous observations of local moon aurora and the moon footprints in Jupiter’s polar aurora
Roth, Lorenz; Grodent, Denis ULiege; Gladstone, Randy et al

Conference (2017, December 12)

The interaction of the co-rotating magnetospheric plasma with Jupiter’s Galilean moons generates local perturbations and auroral emissions in the moons’ tenuous atmospheres. Alfvén waves are launched by ... [more ▼]

The interaction of the co-rotating magnetospheric plasma with Jupiter’s Galilean moons generates local perturbations and auroral emissions in the moons’ tenuous atmospheres. Alfvén waves are launched by this local interaction and travel along Jupiter’s field lines triggering various effects that finally lead to the auroral moon footprints far away in Jupiter’s polar regions. Within the large Hubble Space Telescope aurora program in support of the NASA Juno mission (HST GO-14634, PI D. Grodent), HST observed the local aurora at the moons Io and Ganymede on three occasions in 2017 while the Juno Ultraviolet Spectrograph simultaneously observed Jupiter’s aurora and the moon footprints. In this presentation, we will provide first results from the first-ever simultaneous moon and footprint observations for the case of Io. We compare the temporal variability of the local moon aurora and the Io footprint, addressing the question how much of the footprint variability originates from changes at the moon source and how much originates from processes in the regions that lie in between the moon and Jupiter’s poles. [less ▲]

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See detailA Study of Local Time Variations of Jupiter’s Ultraviolet Aurora using Juno-UVS
Greathouse, Thomas K; Gladstone, Randy; Versteeg, Maarten H et al

Conference (2017, December 12)

Juno’s Ultraviolet Spectrograph (Juno-UVS) offers unique views of Jupiter’s auroras never before obtained in the UV, observing at all local times (unlike HST observations, limited to the illuminated disk ... [more ▼]

Juno’s Ultraviolet Spectrograph (Juno-UVS) offers unique views of Jupiter’s auroras never before obtained in the UV, observing at all local times (unlike HST observations, limited to the illuminated disk). With Juno’s 2-rpm spin period, the UVS long slit rapidly scans across Jupiter observing narrow stripes or swaths of Jupiter’s poles, from 5 hours prior to perijove until 5 hours after perijove. By rotating a mirror interior to the instrument, UVS can view objects from 60 to 120 degrees off the spacecraft spin axis. This allows UVS to map out the entire auroral oval over multiple spins, even when Juno is very close to Jupiter. Using the first 8 perijove passes, we take a first look for local time effects in Jupiter’s northern and southern auroras. We focus on the strength of auroral oval emissions and polar emissions found poleward of the main oval. Some unique polar emissions of interest include newly discovered polar flare emissions that start off as small localized points of emission but quickly (10’s of sec) evolve into rings. These emissions evolve in such a way as to be reminiscent of raindrops striking a pond. [less ▲]

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See detailCassini UVIS Observations of Saturn during the Grand Finale Orbits (Invited)
Pryor, Wayne R; Esposito, Larry W; West, Robert et al

Conference (2017, December 11)

In 2016 and 2017, the Cassini Saturn orbiter executed a final series of high inclination, low-periapsis orbits ideal for studies of Saturn's polar regions. The Cassini Ultraviolet Imaging Spectrograph ... [more ▼]

In 2016 and 2017, the Cassini Saturn orbiter executed a final series of high inclination, low-periapsis orbits ideal for studies of Saturn's polar regions. The Cassini Ultraviolet Imaging Spectrograph (UVIS) obtained an extensive set of auroral images, some at the highest spatial resolution obtained during Cassini's long orbital mission (2004-2017). In some cases, two or three spacecraft slews at right angles to the long slit of the spectrograph were required to cover the entire auroral region to form auroral images. We will present selected images from this set showing narrow arcs of emission, more diffuse auroral emissions, multiple auroral arcs in a single image, discrete spots of emission, small scale vortices, large-scale spiral forms, and parallel linear features that appear to cross in places like twisted wires. Some shorter features are transverse to the main auroral arcs, like barbs on a wire. UVIS observations were in some cases simultaneous with auroral observations from the Hubble Space Telescope Space Telescope Imaging Spectrograph (STIS) that will also be presented. UVIS polar images also contain spectral information suitable for studies of the auroral electron energy distribution. The long wavelength part of the UVIS polar images contains a signal from reflected sunlight containing absorption signatures of acetylene and other Saturn hydrocarbons. The hydrocarbon spatial distribution will also be examined. [less ▲]

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See detailCassini UVIS Auroral Observations in 2016 and 2017
Pryor, Wayne R.; Esposito, Larry W.; Jouchoux, Alain et al

Poster (2017, December 06)

In 2016 and 2017, the Cassini Saturn orbiter executed a final series of high-inclination, low-periapsis orbits ideal for studies of Saturn's polar regions. The Cassini Ultraviolet Imaging Spectrograph ... [more ▼]

In 2016 and 2017, the Cassini Saturn orbiter executed a final series of high-inclination, low-periapsis orbits ideal for studies of Saturn's polar regions. The Cassini Ultraviolet Imaging Spectrograph (UVIS) obtained an extensive set of auroral images, some at the highest spatial resolution obtained during Cassini's long orbital mission (2004-2017). In some cases, two or three spacecraft slews at right angles to the long slit of the spectrograph were required to cover the entire auroral region to form auroral images. We will present selected images from this set showing narrow arcs of emission, more diffuse auroral emissions, multiple auroral arcs in a single image, discrete spots of emission, small scale vortices, large-scale spiral forms, and parallel linear features that appear to cross in places like twisted wires. Some shorter features are transverse to the main auroral arcs, like barbs on a wire. UVIS observations were in some cases simultaneous with auroral observations from the Cassini Imaging Science Subsystem (ISS) the Cassini Visual and Infrared Mapping Spectrometer (VIMS), and the Hubble Space Telescope Space Telescope Imaging Spectrograph (STIS) that will also be presented. [less ▲]

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See detailDawn Auroral Breakup at Saturn Initiated by Auroral Arcs: UVIS/Cassini Beginning of Grand Finale Phase
Radioti, Aikaterini ULiege; Grodent, Denis ULiege; Yao, Zhonghua ULiege et al

in Journal of Geophysical Research. Space Physics (2017)

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See detailThe Ultraviolet Spectrograph on NASA’s Juno Mission
Gladstone, G Randal; Persyn, Steven C.; Eterno, John S. et al

in Space Science Reviews (2017), 213(1-4), 447-473

The ultraviolet spectrograph instrument on the Juno mission (Juno-UVS) is a long-slit imaging spectrograph designed to observe and characterize Jupiter’s far-ultraviolet (FUV) auroral emissions. These ... [more ▼]

The ultraviolet spectrograph instrument on the Juno mission (Juno-UVS) is a long-slit imaging spectrograph designed to observe and characterize Jupiter’s far-ultraviolet (FUV) auroral emissions. These observations will be coordinated and correlated with those from Juno’s other remote sensing instruments and used to place in situ measurements made by Juno’s particles and fields instruments into a global context, relating the local data with events occurring in more distant regions of Jupiter’s magnetosphere. Juno-UVS is based on a series of imaging FUV spectrographs currently in flight—the two Alice instruments on the Rosetta and New Horizons missions, and the Lyman Alpha Mapping Project on the Lunar Reconnaissance Orbiter mission. However, Juno-UVS has several important modifications, including (1) a scan mirror (for targeting specific auroral features), (2) extensive shielding (for mitigation of electronics and data quality degradation by energetic particles), and (3) a cross delay line microchannel plate detector (for both faster photon counting and improved spatial resolution). This paper describes the science objectives, design, and initial performance of the Juno-UVS. [less ▲]

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See detailSun-Earth Interaction
Grodent, Denis ULiege

Learning material (2017)

Sun-Earth Interaction

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See detailRadiative Transfer
Grodent, Denis ULiege

Learning material (2017)

Radiative Transfer

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See detailNew low electron flux facility in the 0 to 3.5 MeV range for the study of induced signal in JUICE instruments: UVS and MAJIS measurements
Carapelle, Alain ULiege; Grodent, Denis ULiege; Langevin, Yves et al

Poster (2017, October)

We designed and built a new test facility to investigate signal induced by electrons in the 0-3.5 MeV in the JUICE UVS and MAJIS instruments. The facility uses radioisotopes sources to produce low flux of ... [more ▼]

We designed and built a new test facility to investigate signal induced by electrons in the 0-3.5 MeV in the JUICE UVS and MAJIS instruments. The facility uses radioisotopes sources to produce low flux of electrons (< 6000 electrons/cm².s). We present the facility, its capabilities and the results of measurements on UVS and MAJIS. [less ▲]

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See detailIntroduction (master in aerospace engineering)
Grodent, Denis ULiege

Learning material (2017)

Introduction

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See detailAtmospheric structure
Grodent, Denis ULiege

Learning material (2017)

Atmospheric structure

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See detailIntroduction
Grodent, Denis ULiege

Learning material (2017)

Introduction

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