Subsurface signatures of bright terrain formation models on Ganymede by 3D radar sounder simulations

Sbalchiero, Elisa; Thakur, Sanchari; Cortellazzi, Marco; Bruzzone, Lorenzo

doi:10.1016/j.icarus.2022.115351

Cited by 4 publications

(3 citation statements)

References 18 publications

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“…More recently, Sbalchiero et al. (2023) published scattering simulation results that appear qualitatively similar to synthetic radargrams in Figure 14 (see Figure 5 in their work). Interestingly, they also applied a facet method and employed a synthetic DEM meant to represent grooved terrain on Ganymede.…”

Section: Simulations Of the Clutter Noise Expected In Nippur Sulcussupporting

confidence: 56%

“…Interestingly, they also applied a facet method and employed a synthetic DEM meant to represent grooved terrain on Ganymede. Although Sbalchiero et al (2023) do not report explicitly the statistical properties of the synthetic DEM, their Table 2 can be used to reproduce it and estimate its statistics. Because of the way in which the synthetic topographic profile is defined, the distribution of slopes is markedly different from the one shown in Figure 13, but the median value is above 70°.…”

Section: Simulations Of the Clutter Noise Expected In Nippur Sulcusmentioning

confidence: 99%

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Multidisciplinary Analysis of the Nippur Sulcus Region on Ganymede

et al. 2023

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On Jupiter's largest moon Ganymede, we focus on the southern region of Nippur Sulcus, including the Epigeus palimpsest crater. This region displays geologically recent terrains and has good coverage of optical and near infrared remote sensing data, primarily returned by the NASA Galileo mission. We first use high‐resolution optical imagery to carry out a detailed geological mapping. We combine hyperspectral data to infer the surface composition of this area. We then apply two theoretical models. The first is a self‐similar clustering that uses the mapping of the grooves present in this region to infer the thickness of the ice shell. A second model is used to estimate the radar clutter noise induced by the estimated local topography, which is key for constraining future radar measurements. Based on all findings, we provide a possible evolutionary history of the Nippur Sulcus and Epigeus areas. This exercise shows the potential of an interdisciplinary data analysis combining wide‐ranging scientific objectives such as geology, surface composition, and geophysics in view of the future close exploration that will be conducted on Ganymede by the JUICE spacecraft. Our work combines multiple analysis techniques that could be applied to other regions of interest and will prove crucial when JUICE data become available.

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Section: Simulations Of the Clutter Noise Expected In Nippur Sulcussupporting

confidence: 56%

Section: Simulations Of the Clutter Noise Expected In Nippur Sulcusmentioning

confidence: 99%

Multidisciplinary Analysis of the Nippur Sulcus Region on Ganymede

et al. 2023

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“…NASA's Europa Clipper mission is slated to overfly both Tyre and Callanish in the early 2030s. Along with complete and higherresolution image coverage and topographic and compositional mapping, ice-penetrating radar sounding has the potential to definitively prove or disprove the hypotheses advanced here (see, e.g., Sbalchiero et al, 2023). Ice penetrating radar has the possibility to provide a much clearer picture of the subsurface structures in the realm of the ring graben and bear on whether the graben fractures may facilitate material communication between the surface and the ocean.…”

Section: Discussionmentioning

confidence: 80%

Thin Ice Lithospheres and High Heat Flows on Europa From Large Impact Structure Ring‐Graben

Singer,

McKinnon,

Schenk

2023

JGR Planets

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Craters are probes of planetary surface and interior properties. Here we measure depths, widths, and spacing of circumferential ring‐graben surrounding the two largest multiring impact structures on Europa, Tyre and Callanish. We estimate formation conditions including the ice shell structure. The radial extension necessary to form these graben is thought to be caused by asthenospheric drag of warmer, more ductile ice and/or water flowing toward the excavated center of the crater, under a brittle‐elastic lithospheric lid. Measurements of graben depths from stereo‐photoclinometric digital elevation models result in estimates of displacement, strain, and stress experienced by the ice shell. Graben widths are used to estimate the intersection depth of the bounding normal faults, a quantity related to the brittle‐ductile transition depth that approximates elastic shell thickness during crater collapse. Heat flows at the time of crater formation as well as ice lithosphere and total shell thickness are thus also constrained. Average widths and depths tend to decrease with increasing distance from the structure center, while inter‐graben spacing generally increases. Varied assumptions yield plausible total conductive ice shell thickness estimates between 4–8 and 2.5–5 km for Tyre and Callanish, respectively, and heat flows of ∼70–115 (±30) mW m−2 for realistic thermal conductivities, consistent with other geophysical estimates for Europa. Higher heat flows are consistent with thin (≲10 km), conductive ice shells and impact breaching, or penetration of the stagnant lid for a convecting ice shell. Callanish, geologically younger, formed in a time or region of greater heat flow than Tyre.

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Geophysical Characterization of the Interiors of Ganymede, Callisto and Europa by ESA’s JUpiter ICy moons Explorer

Van Hoolst,

Tobie,

Vallat

et al. 2024

Space Sci Rev

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The JUpiter ICy moons Explorer (JUICE) of ESA was launched on 14 April 2023 and will arrive at Jupiter and its moons in July 2031. In this review article, we describe how JUICE will investigate the interior of the three icy Galilean moons, Ganymede, Callisto and Europa, during its Jupiter orbital tour and the final orbital phase around Ganymede. Detailed geophysical observations about the interior of the moons can only be performed from close distances to the moons, and best estimates of signatures of the interior, such as an induced magnetic field, tides and rotation variations, and radar reflections, will be obtained during flybys of the moons with altitudes of about 1000 km or less and during the Ganymede orbital phase at an average altitude of 490 km. The 9-month long orbital phase around Ganymede, the first of its kind around another moon than our Moon, will allow an unprecedented and detailed insight into the moon’s interior, from the central regions where a magnetic field is generated to the internal ocean and outer ice shell. Multiple flybys of Callisto will clarify the differences in evolution compared to Ganymede and will provide key constraints on the origin and evolution of the Jupiter system. JUICE will visit Europa only during two close flybys and the geophysical investigations will focus on selected areas of the ice shell. A prime goal of JUICE is the characterisation of the ice shell and ocean of the Galilean moons, and we here specifically emphasise the synergistic aspects of the different geophysical investigations, showing how different instruments will work together to probe the hydrosphere. We also describe how synergies between JUICE instruments will contribute to the assessment of the deep interior of the moons, their internal differentiation, dynamics and evolution. In situ measurements and remote sensing observations will support the geophysical instruments to achieve these goals, but will also, together with subsurface radar sounding, provide information about tectonics, potential plumes, and the composition of the surface, which will help understanding the composition of the interior, the structure of the ice shell, and exchange processes between ocean, ice and surface. Accurate tracking of the JUICE spacecraft all along the mission will strongly improve our knowledge of the changing orbital motions of the moons and will provide additional insight into the dissipative processes in the Jupiter system. Finally, we present an overview of how the geophysical investigations will be performed and describe the operational synergies and challenges.

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Subsurface signatures of bright terrain formation models on Ganymede by 3D radar sounder simulations

Cited by 4 publications

References 18 publications

Multidisciplinary Analysis of the Nippur Sulcus Region on Ganymede

Multidisciplinary Analysis of the Nippur Sulcus Region on Ganymede

Thin Ice Lithospheres and High Heat Flows on Europa From Large Impact Structure Ring‐Graben

Geophysical Characterization of the Interiors of Ganymede, Callisto and Europa by ESA’s JUpiter ICy moons Explorer

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