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See detailMartian dust storm impact on atmospheric H 2 O and D/H observed by ExoMars Trace Gas Orbiter
Vandaele, A. C.; Korablev, O.; Daerden, F. et al

in Nature (2019), 568

Global dust storms on Mars are rare 1,2 but can affect the Martian atmosphere for several months. They can cause changes in atmospheric dynamics and inflation of the atmosphere 3 , primarily owing to ... [more ▼]

Global dust storms on Mars are rare 1,2 but can affect the Martian atmosphere for several months. They can cause changes in atmospheric dynamics and inflation of the atmosphere 3 , primarily owing to solar heating of the dust 3 . In turn, changes in atmospheric dynamics can affect the distribution of atmospheric water vapour, with potential implications for the atmospheric photochemistry and climate on Mars 4 . Recent observations of the water vapour abundance in the Martian atmosphere during dust storm conditions revealed a high-altitude increase in atmospheric water vapour that was more pronounced at high northern latitudes 5,6 , as well as a decrease in the water column at low latitudes 7,8 . Here we present concurrent, high-resolution measurements of dust, water and semiheavy water (HDO) at the onset of a global dust storm, obtained by the NOMAD and ACS instruments onboard the ExoMars Trace Gas Orbiter. We report the vertical distribution of the HDO/H 2 O ratio (D/H) from the planetary boundary layer up to an altitude of 80 kilometres. Our findings suggest that before the onset of the dust storm, HDO abundances were reduced to levels below detectability at altitudes above 40 kilometres. This decrease in HDO coincided with the presence of water-ice clouds. During the storm, an increase in the abundance of H 2 O and HDO was observed at altitudes between 40 and 80 kilometres. We propose that these increased abundances may be the result of warmer temperatures during the dust storm causing stronger atmospheric circulation and preventing ice cloud formation, which may confine water vapour to lower altitudes through gravitational fall and subsequent sublimation of ice crystals 3 . The observed changes in H 2 O and HDO abundance occurred within a few days during the development of the dust storm, suggesting a fast impact of dust storms on the Martian atmosphere. © 2019, The Author(s), under exclusive licence to Springer Nature Limited. [less ▲]

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See detailNo detection of methane on Mars from early ExoMars Trace Gas Orbiter observations
Korablev, O.; Vandaele, A. C.; Montmessin, F. et al

in Nature (2019), 568

The detection of methane on Mars has been interpreted as indicating that geochemical or biotic activities could persist on Mars today 1 . A number of different measurements of methane show evidence of ... [more ▼]

The detection of methane on Mars has been interpreted as indicating that geochemical or biotic activities could persist on Mars today 1 . A number of different measurements of methane show evidence of transient, locally elevated methane concentrations and seasonal variations in background methane concentrations 2–5 . These measurements, however, are difficult to reconcile with our current understanding of the chemistry and physics of the Martian atmosphere 6,7 , which—given methane’s lifetime of several centuries—predicts an even, well mixed distribution of methane 1,6,8 . Here we report highly sensitive measurements of the atmosphere of Mars in an attempt to detect methane, using the ACS and NOMAD instruments onboard the ESA-Roscosmos ExoMars Trace Gas Orbiter from April to August 2018. We did not detect any methane over a range of latitudes in both hemispheres, obtaining an upper limit for methane of about 0.05 parts per billion by volume, which is 10 to 100 times lower than previously reported positive detections 2,4 . We suggest that reconciliation between the present findings and the background methane concentrations found in the Gale crater 4 would require an unknown process that can rapidly remove or sequester methane from the lower atmosphere before it spreads globally. [less ▲]

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See detailH3+ characteristics in the Jupiter atmosphere as observed at limb with Juno/JIRAM
Migliorini, Alessandra; Dinelli, B.M.; Moriconi, M.L. et al

in Icarus (2019), 329

NASA’s Juno spacecraft has been orbiting Jupiter since August 2016, providing unprecedented insights into the giant planet’s atmosphere. The Jupiter Infrared Auroral Mapper (JIRAM) experiment on board ... [more ▼]

NASA’s Juno spacecraft has been orbiting Jupiter since August 2016, providing unprecedented insights into the giant planet’s atmosphere. The Jupiter Infrared Auroral Mapper (JIRAM) experiment on board Juno has made spectroscopic observations of the trihydrogen cation (H3+) emissions in both northern and southern auroral regions (Dinelli et al. 2017; Adriani et al. 2017; Mura et al. 2017) and at mid-to-low latitudes (this paper). Observations targeting the limb of the planet from 60° North to 60° South latitudes were acquired with JIRAM’s spectrometer in August 2016 and March 2017. We use these observations to characterize, for the first time, the vertical distribution of the H3+ emissions as a function of latitude across Jupiter’s sunlit face dayside. H3+ emission features in the 3-4 μm spectral band were used to retrieve the H3+ volume mixing ratio (VMR) and atmospheric temperatures as a function of altitude. The H3+ density profile has a quasi-symmetric distribution with latitude, decreasing from 5×105 cm-3 at 500 km altitude above the 1-bar level to 2×105 cm-3 at 650 km (column densities of 3.5×1013 cm-2 to 1.4×1013 cm-2, assuming a 700 km column depth; altitudes are referenced to 1-bar pressure level). The H3+ VMR is higher in the Southern hemisphere than in the North with values at 500 km altitude of ~4×10-4 ppmv at 40°N and ~8×10-4 ppmv at 40°S. Retrieved temperatures increase almost monotonically with increasing altitude, hovering around 400 K at 300 km and greater than 900 K at about 700 km. [less ▲]

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See detailObservations of satellite footprints in Jupiter's Aurorae
Mura, A.; Adriani, A.; Altieri, F. et al

Conference (2018, December 12)

JIRAM (Jovian Infrared Auroral Mapper) on board Juno is an imager/spectrometer in the 2-5 um range. One imaging channel is designed to study the Jovian H3+ auroral emissions. Its high angular resolution ... [more ▼]

JIRAM (Jovian Infrared Auroral Mapper) on board Juno is an imager/spectrometer in the 2-5 um range. One imaging channel is designed to study the Jovian H3+ auroral emissions. Its high angular resolution, combined with the unique vantage point provided by Juno, allows JIRAM to observe the aurorae in unprecedented detail. Here we present the results from ~2 years of observations of the auroral footprints of the Galilean moons. These are bright spots and associated tail that appear in Jupiter’s ionosphere at the base of the magnetic field lines which sweep past Io, Europa, and Ganymede. The moons are obstacles in the path of Jupiter’s rapidly rotating magnetospheric plasma, and the resulting electromagnetic interaction launches Alfvén waves along the magnetic field towards Jupiter, where intense electron bombardment of the hydrogen atmosphere causes it to glow. Recent observations reveal for the first time that the footprint of Io is comprised of a regularly spaced array of emission features, extending downstream of the leading footprint. Contrary to the larger spots seen in lower resolution images, the small scale of these multiple features (~100 km) is incompatible with the simple paradigm of multiple Alfvén wave reflections. Additionally, observations of Io’s trailing tail well downstream of the main footprint reveal a pair of closely spaced parallel arcs, previously unresolved. The temperatures of the main spot and tail, retrieved with the JIRAM spectrometer, are lower than the main auroral oval. This could indicate that the emission is located at a deeper level, possibly caused by higher energy electrons. Ganymede’s footprint spots (main and secondary) appear as a pair of emission features that provide a remote measure of the size Ganymede’s magnetosphere, mapped from its distant orbit onto Jupiter’s magnetosphere. [less ▲]

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See detailNOMAD, an Integrated Suite of Three Spectrometers for the ExoMars Trace Gas Mission: Technical Description, Science Objectives and Expected Performance
Vandaele, A. C.; Lopez-Moreno, J.-J.; Patel, M. R. et al

in Space Science Reviews (2018), 214

The NOMAD ("Nadir and Occultation for MArs Discovery") spectrometer suite on board the ExoMars Trace Gas Orbiter (TGO) has been designed to investigate the composition of Mars' atmosphere, with a ... [more ▼]

The NOMAD ("Nadir and Occultation for MArs Discovery") spectrometer suite on board the ExoMars Trace Gas Orbiter (TGO) has been designed to investigate the composition of Mars' atmosphere, with a particular focus on trace gases, clouds and dust. The detection sensitivity for trace gases is considerably improved compared to previous Mars missions, compliant with the science objectives of the TGO mission. This will allow for a major leap in our knowledge and understanding of the Martian atmospheric composition and the related physical and chemical processes. The instrument is a combination of three spectrometers, covering a spectral range from the UV to the mid-IR, and can perform solar occultation, nadir and limb observations. In this paper, we present the science objectives of the instrument and explain the technical principles of the three spectrometers. We also discuss the expected performance of the instrument in terms of spatial and temporal coverage and detection sensitivity. [less ▲]

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See detailJuno/JIRAM Observations of Jupiter’s Main Aurorae and Satellite Footprints.
Mura, A.; Adriani, A.; Connerney, J. E. P. et al

Conference (2018, June)

JIRAM (Jovian Infrared Auroral Mapper) on board the NASA/Juno spacecraft is an imaging /spectrometer in the 2-5 um range. One of the imager channels (L band 3.3-3.6 um) is designed to study the Jovian H3 ... [more ▼]

JIRAM (Jovian Infrared Auroral Mapper) on board the NASA/Juno spacecraft is an imaging /spectrometer in the 2-5 um range. One of the imager channels (L band 3.3-3.6 um) is designed to study the Jovian H3+ auroral emission. The very good angular resolution of the camera, combined with the unique vantage point provided by Juno, allows to JIRAM to observe the aurorae with unprecedented details. Here we present the results of ~2 years of auroral observations, with particular emphasis  on the auroral footprints of the Galilean moons. These are bright spots (with associated tail) that appear in Jupiter’s ionosphere at the base of the magnetic field lines that sweep past Io, Europa, and Ganymede. The moons are obstacles in the path of Jupiter’s rapidly rotating magnetospheric plasma and the resulting electromagnetic interaction launches Alfvén waves along the magnetic field towards Jupiter, where intense electron bombardment of the hydrogen atmosphere causes it to glow. Recent observations reveal for the first time that the footprint of Io is comprised of a regularly spaced array of emission features, extending downstream of the leading footprint, resembling a repeating pattern of swirling vortices (von Kármán vortex street) shed by a cylinder in the path of a flowing fluid. Contrary to the larger spots seen in the UV, the small scale of these multiple features (~100 km) is incompatible with the simple paradigm of multiple Alfvén wave reflections. The small scale of these multiple features (~100 km) shows that this particular multiplicity is not generated by multiple Alfven wave reflections. Observations of Io’s trailing tail well downstream of the leading feature reveal a pair of closely spaced parallel arcs that were previously unresolved. Both of Ganymede’s footprint spots (main and secondary) appear as a pair of emission features that evidently provides a remote measure of Ganymede’s magnetosphere, mapped from its distant orbit onto Jupiter’s ionosphere. [less ▲]

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See detailJuno/JIRAM observation of Io and Ganymede's auroral footprints and associated tails
Mura, A.; Adriani, A.; Bolton, S. et al

in EGU General Assembly Conference Abstracts (2018, April)

JIRAM (Jovian Infrared Auroral Mapper) is an imaging spectrometer on board the NASA/Juno spacecraft. The throughput of one of the imager channels (L band) is designed to observe the auroral emission due ... [more ▼]

JIRAM (Jovian Infrared Auroral Mapper) is an imaging spectrometer on board the NASA/Juno spacecraft. The throughput of one of the imager channels (L band) is designed to observe the auroral emission due to the H3+ ion; the surface resolution, when Juno is close to Jupiter's poles, is as small as 10 km. Combined with the unique vantage point provided by Juno, JIRAM observed the auroral footprints with unprecedented details. These auroral footprints are made of bright spots (and an associated tail) that appear in Jupiter's ionosphere at the foot of the magnetic field lines that swept past Io, Europa, and Ganymede. The moons are slow-moving obstacles in the path of Jupiter's rapidly rotating magnetospheric plasma and the resulting electromagnetic interaction launches Alfven waves along the magnetic field lines towards Jupiter, where an intense electron bombardment of the hydrogen atmosphere causes it to glow. Recent observations reveal for the first time that the footprint of Io consists of a regularly spaced array of emission features, extending downstream of the leading footprint, resembling a repeating pattern of swirling vortices (von Kármán vortex street) shed by a cylinder in the path of a flowing fluid. The small scale of these multiple features ( 100 km) is incompatible with the simple paradigm of multiple Alfven wave reflections, which indeed explain the large scale multiplicity already observed. Observations of Io's trailing tail well downstream of the leading feature reveal a pair of closely spaced parallel arcs that were previously unresolved by Earth orbit observations. Both of Ganymede's footprint components (main and secondary) appear as a pair of emission features that evidently provides a remote measure of Ganymede's magnetosphere, mapped from its distant orbit onto Jupiter's ionosphere. [less ▲]

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See detailThe Atmospheric Chemistry Suite (ACS) of Three Spectrometers for the ExoMars 2016 Trace Gas Orbiter
Korablev, O.; Montmessin, F.; Trokhimovskiy, A. et al

in Space Science Reviews (2018), 214

The Atmospheric Chemistry Suite (ACS) package is an element of the Russian contribution to the ESA-Roscosmos ExoMars 2016 Trace Gas Orbiter (TGO) mission. ACS consists of three separate infrared ... [more ▼]

The Atmospheric Chemistry Suite (ACS) package is an element of the Russian contribution to the ESA-Roscosmos ExoMars 2016 Trace Gas Orbiter (TGO) mission. ACS consists of three separate infrared spectrometers, sharing common mechanical, electrical, and thermal interfaces. This ensemble of spectrometers has been designed and developed in response to the Trace Gas Orbiter mission objectives that specifically address the requirement of high sensitivity instruments to enable the unambiguous detection of trace gases of potential geophysical or biological interest. For this reason, ACS embarks a set of instruments achieving simultaneously very high accuracy (ppt level), very high resolving power (>10,000) and large spectral coverage (0.7 to 17 μm—the visible to thermal infrared range). The near-infrared (NIR) channel is a versatile spectrometer covering the 0.7-1.6 μm spectral range with a resolving power of ˜20,000. NIR employs the combination of an echelle grating with an AOTF (Acousto-Optical Tunable Filter) as diffraction order selector. This channel will be mainly operated in solar occultation and nadir, and can also perform limb observations. The scientific goals of NIR are the measurements of water vapor, aerosols, and dayside or night side airglows. The mid-infrared (MIR) channel is a cross-dispersion echelle instrument dedicated to solar occultation measurements in the 2.2-4.4 μm range. MIR achieves a resolving power of >50,000. It has been designed to accomplish the most sensitive measurements ever of the trace gases present in the Martian atmosphere. The thermal-infrared channel (TIRVIM) is a 2-inch double pendulum Fourier-transform spectrometer encompassing the spectral range of 1.7-17 μm with apodized resolution varying from 0.2 to 1.3 cm[SUP]-1[/SUP]. TIRVIM is primarily dedicated to profiling temperature from the surface up to ˜60 km and to monitor aerosol abundance in nadir. TIRVIM also has a limb and solar occultation capability. The technical concept of the instrument, its accommodation on the spacecraft, the optical designs as well as some of the calibrations, and the expected performances for its three channels are described. [less ▲]

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See detailJuno observations of spot structures and a split tail in Io-induced aurorae on Jupiter
Mura, A.; Adriani, A.; Connerney, J. E. P. et al

in Science (2018)

Jupiter’s aurorae are produced in its upper atmosphere when incoming high-energy electrons precipitate along the planet's magnetic field lines. A northern and a southern main auroral oval are visible ... [more ▼]

Jupiter’s aurorae are produced in its upper atmosphere when incoming high-energy electrons precipitate along the planet's magnetic field lines. A northern and a southern main auroral oval are visible, surrounded by small emission features associated with the Galilean moons. We present infrared observations, obtained with the Juno spacecraft, showing that in the case of Io, this emission exhibits a swirling pattern that is similar in appearance to a von Kármán vortex street. Well downstream of the main auroral spots the extended tail is split in two. Both of Ganymede’s footprints also appear as a pair of emission features, which may provide a remote measure of Ganymede’s magnetosphere. These features suggest that magnetohydrodynamic interaction between Jupiter and its moon is more complex than previously anticipated. © The Author(s) 2017. [less ▲]

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See detailConcurrent ultraviolet and infrared observations of the north Jovian aurora during Juno's first perijove
Gérard, Jean-Claude ULiege; Mura, A.; Bonfond, Bertrand ULiege et al

in Icarus (2018), 312

The UltraViolet Spectrograph (UVS) and the Jupiter InfraRed Auroral Mapper (JIRAM) observed the north polar aurora before the first perijove of the Juno orbit (PJ1) on 27 August 2016. The UVS bandpass ... [more ▼]

The UltraViolet Spectrograph (UVS) and the Jupiter InfraRed Auroral Mapper (JIRAM) observed the north polar aurora before the first perijove of the Juno orbit (PJ1) on 27 August 2016. The UVS bandpass corresponds to the H2 Lyman and Werner bands that are directly excited by collisions of auroral electrons with molecular hydrogen. The spectral window of the JIRAM L-band imager includes some of the brightest H3+ thermal features between 3.3 and 3.6 µm. A series of spatial scans obtained with JIRAM every 30 s is used to build up five quasi-global images, each covering ∼12 min. of observations. JIRAM's best spatial resolution was on the order of 50 km/pixel during this time frame, while UVS has a resolution of about 750 km. Most of the observed large-scale auroral features are similar in the two spectral regions, but important differences are also observed in their morphology and relative intensity. Only a part of the UV-IR differences stems from the higher spatial resolution of JIRAM, as some of them are still present following smoothing of the JIRAM images at the UVS resolution. For example, the JIRAM images show persistent narrow arc structures in the 100°–180° SIII longitude sector at dusk not resolved in the ultraviolet, but consistent with the structure of in situ electron precipitation measured two hours later. The comparison between the H2 intensity and the H3+ radiance measured along two radial cuts from the center of the main emission illustrates the complex relation between the electron energy input, their characteristic energy and the H3+ emission. Low values of the H3+ intensity relative to the H2 brightness are observed in regions of high FUV color ratio corresponding to harder electron precipitation. The rapid loss of H3+ ions reacting with methane near and below the homopause appears to play a significant role in the control of the relative brightness of the two emissions. Cooling of the auroral thermosphere by H3+ radiation is spatially variable relative to the direct particle heating resulting from the precipitated electron flux. [less ▲]

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See detailH3+ Measurements in the Jovian Atmosphere with JIRAM/Juno
Migliorini, A.; Dinelli, M.L.; Altieri, F. et al

Poster (2017, December)

The NASA Juno mission has been investigating Jupiter’s atmosphere since August 2016, providing unprecedented insights into the giant planet. The Jupiter Infrared Auroral Mapper (JIRAM) experiment, on ... [more ▼]

The NASA Juno mission has been investigating Jupiter’s atmosphere since August 2016, providing unprecedented insights into the giant planet. The Jupiter Infrared Auroral Mapper (JIRAM) experiment, on board Juno, performed spectroscopic observations of the H3+ emissions both in the auroral regions (Dinelli et al., 2017; Adriani et al., 2017; Mura et al., 2017) and at mid latitudes. In the present work, we analyse the observations acquired by the JIRAM spectrometer during the first perijove passage on 26-27 August 2016, when the spacecraft was at about 500,000-1,200,000 km (7-17 RJ) from the planet. During a portion of the observations, the slit of the spectrometer sampled Jupiter’s limb in the latitude range from 30° to 60° in both hemispheres. The limb spectra show the typical features of the H3+ emission in the 3-4 μm spectral range, which are generally used to retrieve the H3+ concentration and temperature in the auroral region. In this work we employ above spectral region to provide new insight into the H3+ vertical distribution. The spatial resolution of the limb observations of Jupiter, ranging between 50 and 130 km, is favorable for investigating the vertical distribution of H3+. The vertical profiles of the H3+ limb intensity will be presented along with the preliminary results of the retrieval on H3+ vertical volume mixing ratio (VMR) height profiles, and comparison with predictions from the available atmospheric models of the planet. Possible variability of the altitude of the peak emission with respect to latitude and longitude will also be discussed. [less ▲]

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See detailJovian aurora from Juno perijove passes: comparison of ultraviolet and infrared images
Gérard, Jean-Claude ULiege; Bonfond, Bertrand ULiege; Adriani, A. et al

Conference (2017, September 01)

The electromagnetic radiation emitted by the Jovian aurora extends from the X-Rays presumably caused by heavy ion precipitation and electron bremsstrahlung to thermal infrared radiation resulting from ... [more ▼]

The electromagnetic radiation emitted by the Jovian aurora extends from the X-Rays presumably caused by heavy ion precipitation and electron bremsstrahlung to thermal infrared radiation resulting from enhanced heating by high-energy charged particles. Many observations have been made since the 1990s with the Hubble Space Telescope, which was able to image the H2 Lyman and Werner bands that are directly excited by collisions of auroral electrons with H2. Ground-based telescopes obtained spectra and images of the thermal H3+ emission produced by charge transfer between H2+ and H+ ions and neutral H2 molecules in the lower thermosphere. However, so far the geometry of the observations limited the coverage from Earth orbit and only one case of simultaneous UV and infrared emissions has been described in the literature. The Juno mission provides the unique advantage to observe both Jovian hemispheres simultaneously in the two wavelength regions simultaneously and offers a more global coverage with unprecedented spatial resolution. This was the case. [less ▲]

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See detailConcurrent ultraviolet and infrared observations of the north Jovian aurora during Juno’s first perijove
Gérard, Jean-Claude ULiege; Bonfond, Bertrand ULiege; Gladstone, G.R. et al

Conference (2017, June 15)

The UltraViolet Spectrograph (UVS) and the Jupiter InfraRed Auroral Mapper (JIRAM) observed the polar aurora during the perijove phase of the first Juno orbit (PJ1) on 27 August 2016. The UVS passband ... [more ▼]

The UltraViolet Spectrograph (UVS) and the Jupiter InfraRed Auroral Mapper (JIRAM) observed the polar aurora during the perijove phase of the first Juno orbit (PJ1) on 27 August 2016. The UVS passband includes H2 bands that are directly excited by collisions of auroral electrons with H2. The JIRAM L-band imager includes some of the brightest H3+ features between 3.3 and 3.6 μ m. The intensity if this IR emission depends on both the column density of H3+ and the temperature in the emitting region. A series of spatial scans obtained every 30 s is used to build up images of the polar regions. JIRAM’s spatial resolution was about 100 km/pixel during most of the observations reported here while UVS has a substantially lower resolution (about 250 km/pixel). Concurrent observations were obtained during about 70 min in the north. We present a set of simultaneous ultraviolet and infrared images and point out similarities and di ff erences in their morphology and brightness distribution. The time evolution in the two spectral domains will be described and interpreted in terms of energy of the auroral electrons, time history of the precipitation and lifetime of the H3+ ions. Ultraviolet color ratio maps visualize the spatial distribution of the characteristic energy of the primary auroral electrons. Other supporting information is provided by the H3+ temperatures and column density maps derived from the analysis of JIRAM spectra covering the 2-5 μm interval. [less ▲]

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See detailInfrared observations of Jovian aurora from Juno's first orbits: Main oval and satellite footprints
Mura, A.; Adriani, A.; Altieri, F. et al

in Geophysical Research Letters (2017), 44(11), 5308-5316

The Jovian Infrared Auroral Mapper (JIRAM) is an imager/spectrometer on board NASA/Juno mission for the study of the Jovian aurorae. The first results of JIRAM's imager channel observations of the H3 ... [more ▼]

The Jovian Infrared Auroral Mapper (JIRAM) is an imager/spectrometer on board NASA/Juno mission for the study of the Jovian aurorae. The first results of JIRAM's imager channel observations of the H3 + infrared emission, collected around the first Juno perijove, provide excellent spatial and temporal distribution of the Jovian aurorae, and show the morphology of the main ovals, the polar regions, and the footprints of Io, Europa and Ganymede. The extended Io “tail” persists for ~3 h after the passage of the satellite flux tube. Multi-arc structures of varied spatial extent appear in both main auroral ovals. Inside the main ovals, intense, localized emissions are observed. In the southern aurora, an evident circular region of strong depletion of H3 + emissions is partially surrounded by an intense emission arc. The southern aurora is brighter than the north one in these observations. Similar, probably conjugate emission patterns are distinguishable in both polar regions. ©2017. American Geophysical Union. All Rights Reserved. [less ▲]

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See detailPreliminary JIRAM results from Juno polar observations: 3. Evidence of diffuse methane presence in the Jupiter auroral regions
Moriconi, M. L.; Adriani, A.; Dinelli, B. M. et al

in Geophysical Research Letters (2017), 44(10), 4641-4648

Throughout the first orbit of the NASA Juno mission around Jupiter, the Jupiter InfraRed Auroral Mapper (JIRAM) targeted the northern and southern polar regions several times. The analyses of the acquired ... [more ▼]

Throughout the first orbit of the NASA Juno mission around Jupiter, the Jupiter InfraRed Auroral Mapper (JIRAM) targeted the northern and southern polar regions several times. The analyses of the acquired images and spectra confirmed a significant presence of methane (CH4) near both poles through its 3.3 μm emission overlapping the H3 + auroral feature at 3.31 μm. Neither acetylene (C2H2) nor ethane (C2H6) have been observed so far. The analysis method, developed for the retrieval of H3 + temperature and abundances and applied to the JIRAM-measured spectra, has enabled an estimate of the effective temperature for methane peak emission and the distribution of its spectral contribution in the polar regions. The enhanced methane inside the auroral oval regions in the two hemispheres at different longitude suggests an excitation mechanism driven by energized particle precipitation from the magnetosphere. ©2017. American Geophysical Union. All Rights Reserved. [less ▲]

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See detailPreliminary JIRAM results from Juno polar observations: 1. Methodology and analysis applied to the Jovian northern polar region
Dinelli, B. M.; Fabiano, F.; Adriani, A. et al

in Geophysical Research Letters (2017), 44(10), 4625-4632

During the first orbit around Jupiter of the NASA/Juno mission, the Jovian Auroral Infrared Mapper (JIRAM) instrument observed the auroral regions with a large number of measurements. The measured spectra ... [more ▼]

During the first orbit around Jupiter of the NASA/Juno mission, the Jovian Auroral Infrared Mapper (JIRAM) instrument observed the auroral regions with a large number of measurements. The measured spectra show both the emission of the H3+ ion and of methane in the 3–4 μm spectral region. In this paper we describe the analysis method developed to retrieve temperature and column density (CD) of the H3+ ion from JIRAM spectra in the northern auroral region. The high spatial resolution of JIRAM shows an asymmetric aurora, with CD and temperature ovals not superimposed and not exactly located where models and previous observations suggested. On the main oval averaged H3+ CDs span between 1.8 × 1012 cm−2 and 2.8 × 1012 cm−2, while the retrieved temperatures show values between 800 and 950 K. JIRAM indicates a complex relationship among H3+ CDs and temperatures on the Jupiter northern aurora. ©2017. American Geophysical Union. All Rights Reserved. [less ▲]

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See detailJIRAM infrared observations of Jupiter Aurorae: results of the first year.
Mura, A.; Adriani, A.; Altieri, F. et al

Conference (2017)

JIRAM (Jovian Infrared Auroral Mapper) is an imaging spectrometer on board the Juno spacecraft, specifically designed to observe the aurorae of Jupiter. Here we show results on JIRAM's data after one year ... [more ▼]

JIRAM (Jovian Infrared Auroral Mapper) is an imaging spectrometer on board the Juno spacecraft, specifically designed to observe the aurorae of Jupiter. Here we show results on JIRAM's data after one year of observations. The footprints of Io, Europa and Ganymede have also been observed and characterized. [less ▲]

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See detailThe EChO science case
Tinetti, Giovanna; Drossart, Pierre; Eccleston, Paul et al

in Experimental Astronomy (2015), 1502

The discovery of almost 2000 exoplanets has revealed an unexpectedly diverse planet population. Observations to date have shown that our Solar System is certainly not representative of the general ... [more ▼]

The discovery of almost 2000 exoplanets has revealed an unexpectedly diverse planet population. Observations to date have shown that our Solar System is certainly not representative of the general population of planets in our Milky Way. The key science questions that urgently need addressing are therefore: What are exoplanets made of? Why are planets as they are? What causes the exceptional diversity observed as compared to the Solar System? EChO (Exoplanet Characterisation Observatory) has been designed as a dedicated survey mission for transit and eclipse spectroscopy capable of observing a large and diverse planet sample within its four-year mission lifetime. EChO can target the atmospheres of super-Earths, Neptune-like, and Jupiter-like planets, in the very hot to temperate zones (planet temperatures of 300K-3000K) of F to M-type host stars. Over the next ten years, several new ground- and space-based transit surveys will come on-line (e.g. NGTS, CHEOPS, TESS, PLATO), which will specifically focus on finding bright, nearby systems. The current rapid rate of discovery would allow the target list to be further optimised in the years prior to EChO's launch and enable the atmospheric characterisation of hundreds of planets. Placing the satellite at L2 provides a cold and stable thermal environment, as well as a large field of regard to allow efficient time-critical observation of targets randomly distributed over the sky. A 1m class telescope is sufficiently large to achieve the necessary spectro-photometric precision. The spectral coverage (0.5-11 micron, goal 16 micron) and SNR to be achieved by EChO, thanks to its high stability and dedicated design, would enable a very accurate measurement of the atmospheric composition and structure of hundreds of exoplanets. [less ▲]

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