Surface, Subsurface and Atmosphere Exchanges on the Satellites of the Outer Solar System

Tobie, G.; Giese, B.; Hurford, T. A.; Lopes-Gautier, R.; Nimmo, F.; Postberg, F.; Retherford, K. D.; Schmidt, Jürgen; Spencer, J. R.; Tokano, Tetsuya; Turtle, E. P.

doi:10.1007/s11214-010-9641-3

Cited by 18 publications

(9 citation statements)

References 199 publications

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“…Unlike rocky material, ice remains brittle up to the melting point and so, consistent with previous studies, we define the brittle-ductile transition as the depth d that a fracture penetrates. We generally assume the brittle layer thickness H b to be 3 km, on the high-end but roughly consistent with Tobie et al [2010], who showed the brittle-ductile transition depth to be 2-3 km, but consider a range of fracture penetration depths. Later, we employ an elastic layer thickness to investigate the flexural response in the ice.…”

Section: An Icy Analog: Enceladus' Structuresupporting

confidence: 64%

On the application of simple rift basin models to the south polar region of Enceladus

2012

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1] The south polar terrain (SPT) of Saturn's moon Enceladus is a mysteriously active region that exhibits intriguing tectonic signatures and widespread fracturing. The central region of the nearly-circular SPT is depressed into the surface by a few hundred meters and bounded by a ring of cliffs roughly 1 km high. In this study, we investigate whether this depression and surrounding mountainous uplift is consistent with the morphology of terrestrial rift basins and the possibility that the SPT could have formed during a tectonic event analogous to those of such rift basins on Earth. Using three mechanical models of basin formation, we compare our predicted topography of the SPT with observed topography of the region. The first of three models we consider assumes crustal stretching by factor b, and predicts a basin depth of roughly 600 m, closely matching previously published estimates of the depth at the SPT. Models of extension and compression, assuming an elastic response in the ice crust, predict best-fit mountain uplift of roughly 1820 m and 1130 m, respectively. Our preferred model suggests that the icy shell in the SPT has been stretched, but the extension is (partially) balanced by compression along the edges of the basin leading to the uplift of the mountains along the boundary, thereby implying that the SPT may have a tectonic origin analogous to that of a terrestrial basin.Citation: Walker, C. C., J. N. Bassis, and M. W. Liemohn (2012), On the application of simple rift basin models to the south polar region of Enceladus,

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Section: An Icy Analog: Enceladus' Structuresupporting

confidence: 64%

On the application of simple rift basin models to the south polar region of Enceladus

2012

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“…But the overall morphology of Haulani's western crater flank shows a planar crater flanks. Liquid cryolava features can be produced by heating [ Cassen et al ., ] or by a release of material from a liquid subsurface layer [ Tobie et al ., ]. Ascent and emplacement of cryolava could be due to compositional buoyancy [ Croft et al ., ].…”

Section: Discussionmentioning

confidence: 99%

Cryogenic flow features on Ceres: Implications for crater‐related cryovolcanism

Krohn

Jaumann

Stephan

et al. 2016

Geophysical Research Letters

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Craters on Ceres, such as Haulani, Kupalo, Ikapati, and Occator show postimpact modification by the deposition of extended plains material with pits, multiple lobate flows, and widely dispersed deposits that form a diffuse veneer on the preexisting surface. Bright material units in these features have a negative spectral slope in the visible range, making it appear bluish with respect to the grey‐toned overall surface of Ceres. We calculate the drop height‐to‐runout length ratio of several flow features and obtain a coefficient of friction of < 0.1: The results imply higher flow efficiency for flow features on Ceres than for similar features on other planetary bodies with similar gravity, suggesting low‐viscosity material. The special association of flow features with impact craters could either point to an impact melt origin or to an exogenic triggering of cryovolcanic processes.

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“…Such compounds may originate within the satellite itself or be introduced by exogenic processes. Endogenic species may in turn have been in place since the original formation of the satellite, or they may have been created by chemical processing in the interior and subsequently emplaced at the surface by endogenic processes such as cryovolcanism or extensional tectonics [Tobie et al, 2010].…”

Section: Composition Of the Upper Layers Of The Icy Galilean Satellitesmentioning

confidence: 99%

Dielectric properties of Jovian satellite ice analogs for subsurface radar exploration: A review

Pettinelli

Cosciotti

Paolo

et al. 2015

Reviews of Geophysics

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The first European mission dedicated to the exploration of Jupiter and its icy moons (JUpiter ICy moons Explorer-JUICE) will be launched in 2022 and will reach its final destination in 2030. The main goals of this mission are to understand the internal structure of the icy crusts of three Galilean satellites (Europa, Ganymede, and Callisto) and, ultimately, to detect Europa's subsurface ocean, which is believed to be the closest to the surface among those hypothesized to exist on these moons. JUICE will be equipped with the 9 MHz subsurface-penetrating radar RIME (Radar for Icy Moon Exploration), which is designed to image the ice down to a depth of 9 km. Moreover, a parallel mission to Europa, which will host onboard REASON (Radar for Europa Assessment and Sounding: Ocean to Near-surface) equipped with 9MHz and 60MHz antennas, has been recently approved by NASA. The success of these experiments strongly relies on the accurate prediction of the radar performance and on the optimal processing and interpretation of radar echoes that, in turn, depend on the dielectric properties of the materials composing the icy satellite crusts. In the present review we report a complete range of potential ice types that may occur on these icy satellites to understand how they may affect the results of the proposed missions. First, we discuss the experimental results on pure and doped water ice in the framework of the Jaccard theory, highlighting the critical aspects in terms of a lack of standard laboratory procedures and inconsistency in data interpretation. We then describe the dielectric behavior of extraterrestrial ice analogs like hydrates and icy mixtures, carbon dioxide ice and ammonia ice. Building on this review, we have selected the most suitable data to compute dielectric attenuation, velocity, vertical resolution, and reflection coefficients for such icy moon environments, with the final goal being to estimate the potential capabilities of the radar missions as a function of the frequency and temperature ranges of interest for the subsurface sounders. We present the different subsurface scenarios and associated radar signal attenuation models that have been proposed so far to simulate the structure of the crust of Europa and discuss the physical and geological nature of various dielectric targets potentially detectable with RIME. Finally, we briefly highlight several unresolved issues that should be addressed, in near future, to improve our capability to produce realistic electromagnetic models of icy moon crusts. The present review is of interest for the geophysical exploration of all solar system bodies, including the Earth, where ice can be present at the surface or at relatively shallow depths.

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Surface, Subsurface and Atmosphere Exchanges on the Satellites of the Outer Solar System

Cited by 18 publications

References 199 publications

On the application of simple rift basin models to the south polar region of Enceladus

On the application of simple rift basin models to the south polar region of Enceladus

Cryogenic flow features on Ceres: Implications for crater‐related cryovolcanism

Dielectric properties of Jovian satellite ice analogs for subsurface radar exploration: A review

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