Simulations of Energetic Neutral Atom Sputtering From Ganymede in Preparation for the JUICE Mission

Pontoni, Angèle; Shimoyama, Manabu; Futaana, Yoshifumi; Fatemi, Shahab; Poppe, A. R.; Wieser, Martin; Barabash, S.

doi:10.1029/2021ja029439

Cited by 7 publications

(18 citation statements)

References 51 publications

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“…In this way, we can perform predictive modeling of observable ENA emissions during scheduled JUICE flybys of Callisto and Europa. Our work also forms the basis for assessing the relative contributions of ENAs emitted from the moons' atmospheres and surfaces (Pontoni et al, 2022) in a future study.…”

Section: Summary and Concluding Remarksmentioning

confidence: 94%

“…Including these effects may rather be the subject of a future study. Sputtering of an icy moon's surface by impinging energetic ions can also result in ENA emissions, as was modeled at Ganymede by Pontoni et al (2022). Our study focuses only on ENA generation from interactions with Callisto's and Europa's atmospheres.…”

Section: Table 2 Energetic Proton Gyroradii In Units Of Respective Mo...mentioning

confidence: 99%

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Emission of Energetic Neutral Atoms From the Magnetosphere‐Atmosphere Interactions at Callisto and Europa

Haynes,

Tippens,

Addison

et al. 2023

JGR Space Physics

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We analyze the emission of energetic neutral atom (ENA) flux from charge exchange between Jovian magnetospheric ions and the atmospheres of Callisto and Europa. For this purpose, we combine the draped electromagnetic fields from a hybrid plasma model with a particle tracing tool for the energetic ions. We determine the ENA flux through a concentric sphere located just outside of each moon's atmosphere, thereby capturing the complete physics imprinted in these emission patterns. In order to constrain the modifications to the ENA emissions that arise from the periodic change of the ambient plasma conditions, we calculate the emission morphology at multiple positions during a Jovian synodic rotation. To isolate the influence of field line draping, we compare to the emission patterns in uniform fields. Our major results are: (a) At Europa and Callisto, the majority of detectable ENA emissions are concentrated into a band normal to the Jovian magnetospheric field. (b) The fraction of observable ENA flux that contributes to this band depends on the number of complete gyrations that the parent ions can complete within the moon's atmosphere. (c) Field line draping partially deflects impinging parent ions around both moons, thereby attenuating the ENA flux and driving significant morphological changes to the emission patterns. (d) The band of elevated ENA flux is locally maximized on the opposite (antipodal) side of the moon where the flux is locally minimized. At Europa, detectable ENA emissions are maximized slightly west of the ramside apex. At Callisto, they maximize near the Jupiter‐facing apex.

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Section: Summary and Concluding Remarksmentioning

confidence: 94%

Section: Table 2 Energetic Proton Gyroradii In Units Of Respective Mo...mentioning

confidence: 99%

Emission of Energetic Neutral Atoms From the Magnetosphere‐Atmosphere Interactions at Callisto and Europa

Haynes,

Tippens,

Addison

et al. 2023

JGR Space Physics

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“…In the Jovian magnetic field, due to the high-energy penetrating fluxes, the sputtering process is expected to be a dominant source (Wieser et al, 2016). The sputtered ENA emission from Ganymede was simulated (Pontoni et al, 2022), showing that the sputtered ENAs from the surface can be detected with JNA. Thus, PEP can map the ion precipitation onto Ganymede (Pontoni et al, 2022).…”

Section: Imaging Energetic Neutral Atomsmentioning

confidence: 99%

“…The sputtered ENA emission from Ganymede was simulated (Pontoni et al, 2022), showing that the sputtered ENAs from the surface can be detected with JNA. Thus, PEP can map the ion precipitation onto Ganymede (Pontoni et al, 2022). The same mapping should also be possible for Callisto.…”

Section: Imaging Energetic Neutral Atomsmentioning

confidence: 99%

Callisto's Atmosphere and Its Space Environment: Prospects for the Particle Environment Package on Board JUICE

Galli

Vorburger

Mogan

et al. 2022

Earth and Space Science

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Callisto is often perceived as a boring and archaic satellite when compared to its seemingly more exciting neighbors: Io is the most volcanically active body in the solar system (Lopes, 2014 and references therein), Europa harbors a global subsurface ocean with features conducive to biology (Hand et al., 2009 and references therein), and Ganymede is the only known satellite in the solar system to possess an intrinsic magnetic field (Kivelson et al., 1996). Moreover, Io and Europa have extremely young surfaces, and Ganymede has many diverse terrains and landforms. In contrast, images of Callisto taken during Voyager flybys revealed a surface sculpted by impacts, making it the most heavily cratered Galilean satellite (Smith, Soderblom, Johnson, et al., 1979;Smith, Soderblom, Beebe, et al., 1979) and one of the oldest surfaces in the solar system. This implied that Callisto's surface was devoid of any active endogenic processes. The stigma of Callisto being an old, frozen, and geologically dead moon persisted until Galileo revealed that it is home to several exciting processes and yet unresolved mysteries of its own. For example, high-resolution images of Callisto taken by Galileo showed a surprisingly near absence of small craters on the surface, implying that, contrary to the aforementioned assumptions made about Callisto's endogenic activity, small crater degradation processes are occurring (Moore et al., 1999). Moore et al. (1999) demonstrated that these features were a result of sublimation-driven landform modification and mass wasting, and suggested Callisto possessed the most degraded surface of the icy Galilean satellites. A recent investigation by Stephan et al. (2020) of the size-distribution of water ice particles on the surface underlined the importance of temperature-driven processes for the physical properties of Callisto's surface, similar to its inner neighbor Ganymede.Although Callisto and Ganymede are of similar size and bulk composition, there are several dichotomies between the two bodies that make for an interesting comparison. While the surface of Ganymede features more diverse and complex terrains (Schenk, 1995), the surface of Callisto, in addition to being the oldest and most heavily

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“…Probing the environment of energetic neutral atoms (ENAs), which are produced from ion impacts on the surface due to backscattering and sputtering, will therefore provide additional insights into the magnetosphere-surface interaction. Pontoni et al (2022) have recently performed modeling of sputtered ENA fluxes from Ganymede to quantify them for different precipitation conditions. However, sputtered ENAs are mostly sensitive to high-energy heavy ions (Poppe et al 2018;Pontoni et al 2022) and are a more indirect signature of the ion impacts.…”

Section: Introductionmentioning

confidence: 99%

Backscattering of Ions Impacting Ganymede’s Surface as a Source for Energetic Neutral Atoms

Szabo,

Poppe,

Mutzke

et al. 2024

ApJL

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Jupiter’s largest moon Ganymede has its own intrinsic magnetic field, which forms a magnetosphere that is embedded within Jupiter’s corotating magnetospheric plasma. This scenario has been shown to lead to complex ion precipitation patterns that have been connected to heterogeneous space weathering across Ganymede’s surface. We present the first simulations of energetic neutral atoms (ENAs) from backscattered H, O, and S ions, accounting for magnetospheric plasma precipitation and Ganymede’s heterogeneous surface composition. Our model shows that backscattering introduces significant atomic H and O populations to Ganymede’s ENA environment, which will allow remote observation of ion–surface interactions at Ganymede. There are distinct differences between H ENA emissions at Ganymede and the Moon, with orders of magnitude lower fluxes below 1 keV but a significant tail above 1 keV. Backscattered H ENAs will also dominate over sputtered H contributions above energies of around 1 keV, while O ENAs are less likely to be distinguished from sputtered ENAs. The backscattered H ENAs thus represent a promising candidate for studying the plasma–surface interaction on Ganymede with future observations of ESA’s JUICE mission.

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Simulations of Energetic Neutral Atom Sputtering From Ganymede in Preparation for the JUICE Mission

Cited by 7 publications

References 51 publications

Emission of Energetic Neutral Atoms From the Magnetosphere‐Atmosphere Interactions at Callisto and Europa

Emission of Energetic Neutral Atoms From the Magnetosphere‐Atmosphere Interactions at Callisto and Europa

Callisto's Atmosphere and Its Space Environment: Prospects for the Particle Environment Package on Board JUICE

Backscattering of Ions Impacting Ganymede’s Surface as a Source for Energetic Neutral Atoms

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