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  • 1
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    The Global Seismic Moment Rate of Mars After Event S1222a (2023)
    Details
    Publication Date: 2023-07-20
    Description: The seismic activity of a planet can be described by the corner magnitude, events larger than which are extremely unlikely, and the seismic moment rate, the long‐term average of annual seismic moment release. Marsquake S1222a proves large enough to be representative of the global activity of Mars and places observational constraints on the moment rate. The magnitude‐frequency distribution of relevant Marsquakes indicates a $b$‐value of 1.06. The moment rate is likely between $1.55\times {10}^{15}\mathrm{N}\mathrm{m}/\mathrm{a}$ and $1.97\times {10}^{18}\mathrm{N}\mathrm{m}/\mathrm{a}$, with a marginal distribution peaking at $4.9\times {10}^{16}\mathrm{N}\mathrm{m}/\mathrm{a}$. Comparing this with pre‐InSight estimations shows that these tended to overestimate the moment rate, and that 30% or more of the tectonic deformation may occur silently, whereas the seismicity is probably restricted to localized centers rather than spread over the entire planet.
    Description: Plain Language Summary: The seismic moment rate is a measure for how fast quakes accumulate deformation of the planet's rigid outer layer, the lithosphere. In the past decades, several models for the deformation rate of Mars were developed either from the traces quakes leave on the surface, or from mathematical models of how quickly the planet's interior cools down and shrinks. The large marsquake that occurred on the 4th of May 2022 now allows a statistical estimation of the deformation accumulated on Mars per year, and thus to confront these models with reality. It turns out that, although there is a considerable overlap, the models published prior to InSight tend to overestimate the seismic moment rate, and hence the ongoing deformation on Mars. Possible explanations are that 30% or more of the deformation occurs silently, that is, without causing quakes, or that not the entire planet is seismically active but only specific regions.
    Description: Key Points: A single large marsquake suffices to constrain the global seismic moment rate. Pre‐InSight estimations tended to overestimate the moment rate. Either a significant part of the ongoing deformation occurs silent, or seismic activity is restricted to some activity centers, or both.
    Description: Eidgenössische Technische Hochschule Zürich http://dx.doi.org/10.13039/501100003006
    Description: National Aeronautics and Space Administration http://dx.doi.org/10.13039/100000104
    Description: UK Space Agency http://dx.doi.org/10.13039/100011690
    Description: Deutsches Zentrum für Luft‐ und Raumfahrt http://dx.doi.org/10.13039/501100002946
    Description: Insight SFI Research Centre for Data Analytics http://dx.doi.org/10.13039/501100021525
    Description: http://dx.doi.org/10.18715/SEIS.INSIGHT.XB_2016
    Description: http://doi.org/10.17189/1517570
    Keywords: ddc:523 ; Mars ; InSight ; seismic moment rate ; S1222a
    Language: English
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  • 2
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    Determination of the lunar body tide from global laser altimetry data (2020)
    Springer Berlin Heidelberg
    Details
    Publication Date: 2023-07-20
    Description: We use global data from the Lunar Orbiter Laser Altimeter (LOLA) to retrieve the lunar tidal Love number h2 and find h2 = 0.0387 ± 0.0025. This result is in agreement with previous estimates from laser altimetry using crossover points of LOLA profiles. The Love numbers k2 and h2 are key constraints on planetary interior models. We further develop and apply a retrieval method based on a simultaneous inversion for the topography and the tidal signal benefiting from the large volume of LOLA data. By the application to the lunar tides, we also demonstrate the potential of the method for future altimetry experiments at other planetary bodies. The results of this study are very promising with respect to the determination of Mercury’s and Ganymede’s h2 from future altimeter measurements.
    Description: DLR Space Administration
    Description: International Max Planck Research School on Solar System Science at the University of Göttingen
    Description: Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659
    Keywords: ddc:523 ; Tides ; Laser altimetry ; Lunar Orbiter Laser Altimeter ; Lunar interior
    Language: English
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  • 3
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    Alternating North‐South Brightness Ratio of Ganymede's Auroral Ovals: Hubble Space Telescope Observations Around the Juno PJ34 Flyby (2022)
    Details
    Publication Date: 2023-11-14
    Description: We report results of Hubble Space Telescope observations from Ganymede's orbitally trailing side which were taken around the flyby of the Juno spacecraft on 7 June 2021. We find that Ganymede's northern and southern auroral ovals alternate in brightness such that the oval facing Jupiter's magnetospheric plasma sheet is brighter than the other one. This suggests that the generator that powers Ganymede's aurora is the momentum of the Jovian plasma sheet north and south of Ganymede's magnetosphere. Magnetic coupling of Ganymede to the plasma sheet above and below the moon causes asymmetric magnetic stresses and electromagnetic energy fluxes ultimately powering the auroral acceleration process. No clear statistically significant timevariability of the auroral emission on short time scales of 100s could be resolved. We show that electron energy fluxes of several tens of mW m−2 are required for its OI 1,356 Å emission making Ganymede a very poor auroral emitter.
    Description: Plain Language Summary: Jupiter's moon Ganymede is the largest moon in the solar system and the only known moon with an intrinsic magnetic field and two auroral ovals around its north and south poles. Earth also possesses two auroral ovals, which are bands of emission around its poles. This emission is also referred to as northern and southern lights. We use the Hubble Space Telescope to observe Ganymede's aurora around the time when NASA's Juno spacecraft had a close flyby at Ganymede. We find that the brightness of the northern and southern ovals alternate in intensity with a period of 10 hr. Additionally, we derive that an energy flux of several tens of milli‐Watt per square meter is necessary to power the auroral emission. This energy flux comes from energetic electrons accelerated in the vicinity of Ganymede.
    Description: Key Points: Hubble Space Telescope observations of Ganymede's orbitally trailing hemisphere on 7 June 2021 in support of Juno flyby. Brightness ratio of northern and southern auroral ovals oscillates such that the oval facing the Jovian plasma sheet is brighter. Oscillation suggests the aurora is driven by magnetic stresses coupling the moon's magnetic field to the surrounding Jovian plasma sheet.
    Description: European Research Council, ERC
    Description: NASA
    Description: http://archive.stsci.edu/hst/
    Keywords: ddc:523 ; Ganymede ; auroral ovals ; Hubble Space Telescope ; Juno spacecraft
    Language: English
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  • 4
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    Spatio‐Temporal Level Variations of the Martian Seasonal South Polar Cap From Co‐Registration of MOLA Profiles (2022)
    Details
    Publication Date: 2022-10-04
    Description: The seasonal deposition and sublimation of CO2 represents a major element in the Martian volatile cycle. Here, co‐registration strategies are applied to Mars Orbiter Laser Altimeter profiles to obtain spatio‐temporal variations in snow/ice level of the Seasonal South Polar Cap (SSPC), in grid elements of 0.5° in latitude from 60° to 87°S and 10° in longitude. The maximum snow/ice level in the range of 2–2.5 m is observed over the Residual South Polar Cap. Peak level at the Residual South Polar Cap in Martian Year 25 (MY25) are found to be typically ∼0.5 m higher than those in MY24. The total volume is estimated to peak at approximately 9.4 × 1012 m3. In addition, a map of average bulk density of the SSPC during its recession is derived. It implies much more snowfall‐like precipitation at the Residual South Polar Cap and its surroundings than elsewhere on Mars.
    Description: Plain Language Summary: Each Martian year, up to one third of the atmosphere's CO2 is transported from pole to pole, being deposited and sublimated depending on the season. Accurate measurements of snow level and volume variations of the resulting seasonal polar caps can serve as crucial constraints on the Martian volatile cycles. In this study, we apply new approaches of analyzing the Mars Orbiter Laser Altimeter profiles, which lead to spatially and temporally resolved measurements of snow/ice level of the Seasonal South Polar Cap (SSPC). Based on that, the maximum snow level, interannual maximum level change from Martian Year 24 (MY24) to MY25, and how the volume of the SSPC changes with time are measured. We also estimate the bulk density of the snow/ice deposition during southern winter. It is inferred that there is much more snowfall at the Residual South Polar Cap and its surroundings than elsewhere on the planet.
    Description: Key Points: Using co‐registration of Mars Orbiter Laser Altimeter profiles, spatio‐temporal level variations of the seasonal snow/ice deposits at the Martian south pole are obtained. Maximum level can be up to 2.5 m; Peak level increased by ∼0.5 m at the Residual South Polar Cap from Martian Year 24 (MY24) to MY25. Obtained bulk density map of the seasonal deposits implies that snowfall concentrates at the Residual South Polar Cap and its surroundings.
    Description: China Scholarship Council
    Description: Deutsche Forschungsgemeinschaft
    Description: Institut National des Sciences de l’Univers
    Description: Centre National de la Recherche Scientifique
    Description: Centre National d’Etudes Spatiales
    Description: https://pds-geosciences.wustl.edu/missions/mgs/pedr.html
    Description: https://naif.jpl.nasa.gov/pub/naif/pds/data/mgs-m-spice-6-v1.0/mgsp_1000/data/
    Description: https://doi.org/10.17632/z59b9nd6s9.2
    Description: https://doi.org/10.14768/8cba4407-d6a0-4d16-aeaf-d0ebfd2b480a
    Keywords: ddc:523
    Language: English
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  • 5
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    Mapping the Brightness of Ganymede's Ultraviolet Aurora Using Hubble Space Telescope Observations (2022)
    Details
    Publication Date: 2022-10-06
    Description: We analyze Hubble Space Telescope observations of Ganymede made with the Space Telescope Imaging Spectrograph between 1998 and 2017 to generate a brightness map of Ganymede's oxygen emission at 1,356 Å. Our Mercator projected map demonstrates that the brightness along Ganymede's northern and southern auroral ovals strongly varies with longitude. To quantify this variation around Ganymede, we investigate the brightness averaged over 36°‐wide longitude corridors centered around the sub‐Jovian (0° W), leading (90° W), anti‐Jovian (180° W), and trailing (270° W) central longitudes. In the northern hemisphere, the brightness of the auroral oval is 3.7 ± 0.4 times lower in the sub‐Jovian and anti‐Jovian corridors compared to the trailing and leading corridors. The southern oval is overall brighter than the northern oval, and only 2.5 ± 0.2 times fainter on the sub‐ and anti‐Jovian corridors compared to the trailing and leading corridors. This demonstrates that Ganymede's auroral ovals are strongly structured in auroral crescents on the leading side (plasma downstream side) and on the trailing side (plasma upstream side). We also find that the brightness is not symmetric with respect to the 270° meridian, but shifted by ∼20° towards the Jovian‐facing hemisphere. Our map will be useful for subsequent studies to understand the processes that generate the aurora in Ganymede's non‐rotationally driven, sub‐Alfvénic magnetosphere.
    Description: Plain Language Summary: Northern lights often illuminate the night sky in a shimmering green or red tone at high geographic latitudes. This emission, scientifically referred to as aurora, is a result of electrically charged particles that move along Earth's magnetic field lines and interact with its atmosphere to produce auroral emission. Apart from the Earth, multiple other planets in our solar system also exhibit auroral emission. By characterizing the brightness and structure of these lights, we are therefore able to deduce insights about a planet's atmosphere, magnetic field and the physical processes occurring along the field lines from afar. In this work, we used observations from the Hubble Space Telescope to analyze the auroral emission of Jupiter's largest moon Ganymede. We combined multiple images of Ganymede to create the first complete map that displays the auroral brightness. Our map revealed that the emission on Ganymede's auroral ovals varies strongly in brightness with divisions into two distinct bright and faint regions. They resemble two auroral crescents in the north and south respectively, and demonstrate the uniqueness of Ganymede's aurora in comparison with the auroral ovals of other planets in the solar system.
    Description: Key Points: Brightness map of Ganymede's ultraviolet auroral emission has been constructed based on Hubble Space Telescope observations from 1998 to 2017. Auroral ovals are structured in upstream and downstream “crescents”. Brightness on sub‐Jovian and anti‐Jovian side is strongly reduced by a factor of 3–4 compared to upstream and downstream side.
    Description: European Research Council (ERC)
    Description: http://archive.stsci.edu/hst/
    Keywords: ddc:523
    Language: English
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  • 6
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    Spatio‐Temporal Level Variations of the Martian Seasonal North Polar Cap From Co‐Registration of MOLA Profiles (2022)
    Xiao, Haifeng ; Stark, Alexander ; Schmidt, Frédéric ; [et al.]
    Details
    Publication Date: 2023-01-14
    Description: The seasonal deposition and sublimation of CO2 constitute a major element in Martian volatile cycles. We reprocess the Mars Orbiter Laser Altimeter (MOLA) data and apply co‐registration procedures to obtain spatio‐temporal variations in levels of the Seasonal North Polar Cap (SNPC). The maximum level over the Residual North Polar Cap (RNPC) is 1.3 m, approximately half of that at the south pole (2.5 m). However, the maximum level in the dune fields at Olympia Undae can be up to 3.8 m. Furthermore, off‐season decreases up to 3 m during the northern winter at Olympia Undae are observed. These are likely due to metamorphism effects accentuated by the reduced snowfall at this period. Meanwhile, off‐season increases of up to 2 m during the northern spring are noted, the cause of which remains to be explored. The volume of the SNPC peaks at the end of northern winter and is estimated to be approximately 9.6 × 1012 m3, which is 2% more than that of the Seasonal South Polar Cap. The bulk density of the SNPC can go through phased decreases in accordance with phased accumulation at northern high‐latitudes. These findings can put important constraints on the Martian volatile cycling models.
    Description: Plain Language Summary: Due to its axial tilt, seasons also exist on Mars. Up to one third of the atmosphere's CO2 is in annual exchange with the polar regions through seasonal deposition/sublimation processes. Here, we make use of previously proposed approaches of analyzing the Mars Orbiter Laser Altimeter profiles and obtain spatio‐temporal level variations of the Seasonal North Polar Cap (SNPC). Particularly, we bring attention to abnormal behavior of the SNPC in the dune fields at Olympia Undae. Maximum level there can be all the way up to 4 m which is much higher than a maximum of 1.5 m over the Residual North Polar Cap. Meanwhile, off‐season decreases during the northern winter with magnitudes up to 3 m and off‐season increases during the northern spring of magnitudes up to 2 m are observed. These could possibly be related to metamorphism of the seasonal deposits and phased snowfall. The maximum volume of the SNPC is constrained to be 9.6 × 1012 m3. The bulk density of the SNPC does not continuously increase as previously assumed but can go through phased decreases in accordance with phased snowfall at the north pole. These findings can put important constraints on the Martian climate models.
    Description: Key Points: Through co‐registration of laser altimetry profiles, spatio‐temporal level variations of the Seasonal North Polar Cap (SNPC) of Mars are obtained. Maximum level of the SNPC can be up to 3.8 m at Olympia Undae and up to 1.3 m over the Residual North Polar Cap. Northern winter decreases of up to 3 m and northern spring increases of up to 2 m are observed at Olympia Undae.
    Description: China Scholarship Council
    Description: Deutsche Forschungsgemeinschaft
    Description: Institut National des Sciences de l’Univers
    Description: Centre National de la Recherche Scientifique
    Description: Centre National d’Etudes Spatiales
    Description: https://doi.org/10.17632/x953mzxxvv.1
    Description: https://doi.org/10.17632/z59b9nd6s9.2
    Description: https://pds-geosciences.wustl.edu/missions/mgs/pedr.html
    Description: https://naif.jpl.nasa.gov/pub/naif/pds/data/mgs-m-spice-6-v1.0/mgsp_1000/data/
    Description: https://www.uahirise.org/hiwish/browse
    Keywords: ddc:523 ; Mars ; seasonal polar cap ; CO2 ice ; MOLA ; level variation ; pseudo cross‐over
    Language: English
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  • 7
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    Properties of Turbulent Alfvénic Fluctuations and Wave‐Particle Interaction Associated With Io's Footprint Tail (2022)
    Details
    Publication Date: 2024-01-12
    Description: We investigate the small‐scale magnetic field fluctuations and their associated turbulent nature in the Io flux tube (IFT) connected to Io's footprint tail (IFPT). Our study is based on the recent magnetic field measurements by the Juno spacecraft during the PJ12 Juno flyby. Here, we are interested in understanding what type of turbulence is consistent with the fluctuations in the quasi‐dispersionless frequency range of 0.2–800 Hz as observed by Sulaiman et al. (2020), https://doi.org/10.1029/2020GL088432. Knowledge of the turbulent fluctuations is important to constrain the acceleration mechanisms for ions and electrons in the IFT. In this work, we suggest that the observed temporal fluctuations in the spacecraft frame correspond to Doppler‐shifted spatial fluctuation structured perpendicular to the background magnetic field. This would imply an alternative reinterpretation of the spectral index of the observed magnetic power spectral density to be potentially the result of weak‐MHD and sub‐ion scale kinetic Alfvén wave turbulence in the low‐frequency regime. Our theoretical modelings show that turbulence can be driven both in the torus region and at high‐latitudes rendering results in agreement with the Juno measurements. Calculated turbulence heating rates are consistent with observed energy fluxes in the IFT and represent efficient drivers for particle acceleration. Moreover, a widening of the IFPT structure with respect to the IFT extent is consistent with propagating dispersive Alfvén waves modified by kinetic effects on their group velocities.
    Description: Key Points: Low‐frequency Juno observations in the Io flux tube (IFT) tail represent structures perpendicular to background magnetic field. Magnetic field fluctuations observed in the Io footprint tail (IFPT) are consistent with weak‐MHD and sub‐ion kinetic Alfvén wave turbulence. Dispersion effects on group velocity of Alfvén waves widens the IFT consistent with the observed width of the IFPT.
    Description: Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659
    Description: https://doi.org/10.17189/1519711
    Description: https://doi.org/10.17189/1522461
    Keywords: ddc:523 ; Io ; Juno observations ; Alfvén waves ; magnetic field fluctuations
    Language: English
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  • 8
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    Interiors of Earth-Like Planets and Satellites of the Solar System (2021)
    Springer Netherlands
    Details
    Publication Date: 2023-08-25
    Description: The Earth-like planets and moons in our solar system have iron-rich cores, silicate mantles, and a basaltic crust. Differentiated icy moons can have a core and a mantle and an outer water–ice layer. Indirect evidence for several icy moons suggests that this ice is underlain by or includes a water-rich ocean. Similar processes are at work in the interiors of these planets and moons, including heat transport by conduction and convection, melting and volcanism, and magnetic field generation. There are significant differences in detail, though, in both bulk chemical compositions and relative volume of metal, rock and ice reservoirs. For example, the Moon has a small core [~ 0.2 planetary radii (RP)], whereas Mercury’s is large (~ 0.8 RP). Planetary heat engines can operate in somewhat different ways affecting the evolution of the planetary bodies. Mercury and Ganymede have a present-day magnetic field while the core dynamo ceased to operate billions of years ago in the Moon and Mars. Planets and moons differ in tectonic style, from plate-tectonics on Earth to bodies having a stagnant outer lid and possibly solid-state convection underneath, with implications for their magmatic and atmosphere evolution. Knowledge about their deep interiors has improved considerably thanks to a multitude of planetary space missions but, in comparison with Earth, the data base is still limited. We describe methods (including experimental approaches and numerical modeling) and data (e.g., gravity field, rotational state, seismic signals, magnetic field, heat flux, and chemical compositions) used from missions and ground-based observations to explore the deep interiors, their dynamics and evolution and describe as examples Mercury, Venus, Moon, Mars, Ganymede and Enceladus.
    Description: Deutsches Zentrum für Luft- und Raumfahrt e. V. (DLR) (4202)
    Keywords: ddc:523 ; Interior structure ; Terrestrial planets and moons ; Space exploration ; Gravity ; Rotation ; Magnetic fields ; Thermal evolution
    Language: English
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  • 9
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    Jovian Auroral Electron Precipitation Budget—A Statistical Analysis of Diffuse, Mono‐Energetic, and Broadband Auroral Electron Distributions (2022)
    Details
    Publication Date: 2023-01-13
    Description: Recent observations by the Juno spacecraft have shown that electrons contributing to Jupiter's main auroral emission appear to be frequently characterized by broadband electron distributions, but also less often mono‐energetic electron distributions are observed as well. In this work, we quantitatively derive the occurrence rates of the various electron distributions contributing to Jupiter's aurora. We perform a statistical analysis of electrons measured by the JEDI‐instrument within 30–1,200 keV from Juno's first 20 orbits. We determine the electron distributions, either pancake, field‐aligned, mono‐energetic, or broadband, through energy and pitch angles to associate various acceleration mechanisms. The statistical analysis shows that field‐aligned accelerated electrons at magnetic latitudes greater than 76° are observed in 87.6% ± 7.2% of the intervals time averaged over the dipole L‐shells according the main oval. Pancake distributions, indicating diffuse aurora, are prominent at smaller magnetic latitudes (〈76°) with an occurrence rate of 86.2% ± 9.6%. Within the field‐aligned electron distributions, we see broadband distributions 93.0% ± 3.8% of the time and a small fraction of isolated mono‐energetic distribution structures 7.0% ± 3.8% of the time. Furthermore, these occurrence statistics coincide with the findings from our energy flux statistics regarding the electron distributions. Occurrence rates thus also characterize the overall energetics of the different distribution types. This study indicates that stochastic acceleration is dominating the auroral processes in contrast to Earth where the discrete aurora is dominating.
    Description: Plain Language Summary: With the Juno spacecraft arriving in the magnetosphere of Jupiter, first flyby particle measurements have changed the knowledge about the developing process of Jupiter's intense aurora. The observations of auroral particles show a stochastic behavior rather than a preference for specific energy. Our statistical analysis of the first 20 flybys at Jupiter compares the occurrence of different particle distributions and highlights the importance of different generation theories for Jupiter's aurora. A generation via stochastic rather than mono‐energetic behavior is deduced and supports previous observations.
    Description: Key Points: We present a statistical study of Jupiter's auroral electrons within 30–1,200 keV based on Juno's first 20 perijoves. Broadband electron distributions dominates Jupiter's main auroral zone as they are observed in 93% ± 3% of the intervals studied here. Dominance of broadband distributions underlines the importance of a turbulent or stochastic acceleration process.
    Description: Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659
    Description: Universität zu Köln http://dx.doi.org/10.13039/501100008001
    Description: https://lasp.colorado.edu/home/mop/files/2015/02/CoOrd_systems7.pdf
    Description: https://pds-ppi.igpp.ucla.edu/mission/JUNO/JNO/JEDI
    Description: https://lasp.colorado.edu/home/mop/files/2020/04/20190412_Imai_MagFootReader_UIowa_rev.pdf
    Keywords: ddc:523 ; auroral precipitation budget ; particle distribution ; Jupiter ; Juno
    Language: English
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  • 10
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    Constraining Europa's Subsolar Atmosphere With a Joint Analysis of HST Spectral Images and Galileo Magnetic Field Data (2022)
    Details
    Publication Date: 2023-01-20
    Description: We constrain Europa's tenuous atmosphere on the subsolar hemisphere by combining two sets of observations: oxygen emissions at 1,304 and 1,356 Å from Hubble Space Telescope (HST) spectral images and Galileo magnetic field measurements from its closest encounter, the E12 flyby. We describe Europa's atmosphere with three neutral gas species: global molecular (O2) and atomic oxygen (O), and localized water (H2O) present as a near‐equatorial plume and as a stable distribution concentrated around the subsolar point on the moon's trailing hemisphere. Our combined modeling based on the ratio of OI 1,356 to OI 1,304 Å emissions from Roth (2021; https://doi.org/10.1029/2021gl094289) and on magnetic field data allows us to derive constraints on the density and location of O2 and H2O in Europa's atmosphere. We demonstrate that 50% of the O2 and between 50% and 75% of the H2O abundances from Roth (2021; https://doi.org/10.1029/2021gl094289) are required to jointly explain the HST and Galileo measurements. These values are conditioned on a column density of O close to the upper limit of 6 × 1016 m−2 derived by Roth (2021; https://doi.org/10.1029/2021gl094289), and on a strongly confined stable H2O atmosphere around the subsolar point. Our analysis yields column densities of 1.2 × 1018 m−2 for O2, and 1.5 × 1019 to 2.2 × 1019 m−2 at the subsolar point for H2O. Both column densities, however, still lie within the uncertainties of Roth (2021; https://doi.org/10.1029/2021gl094289). Our results provide additional evidence for the existence of a stable H2O atmosphere at Europa.
    Description: Key Points: We combine Hubble Space Telescope spectral images and Galileo magnetometer data to constrain the density and location of water vapor in Europa's atmosphere. We simulate the plasma interaction for the Galileo E12 flyby with a three‐component atmosphere: global O2, stable confined H2O, and a plume. Using 50% of O2 and from 50% to 75% of H2O column densities from Roth (2021) yields magnetic field signatures consistent with both observations.
    Description: European Research Council http://dx.doi.org/10.13039/100010663
    Description: http://doi.org/10.17189/1519667
    Keywords: ddc:523 ; Europa ; Jupiter ; moon‐magnetosphere interaction ; icy moons ; atmosphere
    Language: English
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