Strain history of ice shells of the Galilean satellites from radar detection of crystal orientation fabric

Barr, A. C.; Stillman, D. E.

doi:10.1029/2010gl046616

Cited by 8 publications

(8 citation statements)

References 45 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In a convecting shell (where a thick layer of warm ice exists), detection of an ocean is likely to be impossible in most places, except perhaps in localized cold, downwelling regions [ McKinnon , ]. On the other hand, convection may develop anisotropic fabrics in the ice which are also in principle detectable with radar [ Barr and Stillman , ]. Although not yet demonstrated at icy satellites, radar sounding is a promising technique, and sounders form part of the payload of both the Europa Clipper and the JUICE missions [e.g., Bruzzone et al , ].…”

Section: How Are Oceans Detected?mentioning

confidence: 99%

Ocean worlds in the outer solar system

2016

View full text Add to dashboard Cite

Many outer solar system bodies are thought to harbor liquid water oceans beneath their ice shells. This article first reviews how such oceans are detected. We then discuss how they are maintained, when they formed, and what the oceans' likely characteristics are. We focus in particular on Europa, Ganymede, Callisto, Titan, and Enceladus, bodies for which there is direct evidence of subsurface oceans. We also consider candidate ocean worlds such as Pluto and Triton.

show abstract

Section: How Are Oceans Detected?mentioning

confidence: 99%

Ocean worlds in the outer solar system

2016

View full text Add to dashboard Cite

show abstract

“…Dielectric interfaces related to abrupt changes in COF [Barr and Stillman, 2011] could be caused by the strain related to solid-state convection [Goldsby and Kohlstedt, 2002]. On Europa, horizons between regions with different orientation fabrics could be present within the stagnant lid and in the cold downwelling [Barr and Stillman, 2011]. The COF could be connected to the brittle-ductile transition (BDT) within the ice shell.…”

Section: 1002/2014rg000463mentioning

confidence: 99%

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

Pettinelli

Cosciotti

Paolo

et al. 2015

Reviews of Geophysics

View full text Add to dashboard Cite

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.

show abstract

“…This elongation indicates that a planar layer of contrasting velocities (low velocity interior to high velocity exterior) exhibiting high shear would exist through large portions of the middle of the ice shell (Figures and ; similar to shear in the Earth's mantle, e.g., Becker, ). This region would likely have a strong preferred crystallographic orientation and associated anisotropy that may be detectable with radar and seismic acquisitions of active ice shells such as expected for Europa (e.g., Barr & Stillman, ; Panning et al, ; Rudolph & Manga, ; Vance et al, ).…”

Section: Discussionmentioning

confidence: 99%

Convection in Thin Shells of Icy Satellites: Effects of Latitudinal Surface Temperature Variations

et al. 2019

View full text Add to dashboard Cite

We use three‐dimensional numerical experiments of thin shell convection to explore what effects an expected latitudinal variation in solar insolation may have on a convection. We find that a global flow pattern of upwelling equatorial regions and downwelling polar regions, linked to higher and lower surface temperatures (Ts), respectively, is preferred. Due to the gradient in Ts, boundary layer thicknesses vary from equatorial lows to polar highs, and polar oriented flow fields are established. A Hadley cell‐type configuration with two hemispheric‐scale convective cells emerges with heat flow enhanced along the equator and suppressed poleward. The poleward transport pattern appears robust under a range of basal and mixed heating, isoviscous and temperature‐dependent viscosity, vigor of convection, and different degrees of Ts variations. Our findings suggest that a latitudinal variation in Ts is an important effect for convection within the thin ice shells of the outer satellites, becoming increasingly important as solar luminosity increases. Variable Ts models predict lower heat flow and a more compressional regime near downwellings at higher latitudes, and higher heat flow and a more extensional regime near the equator. Within the ice shell, Hadley style flow could lead to large‐scale anisotropic ice properties that might be detectable with future seismic or electro‐magnetic observations.

show abstract

Strain history of ice shells of the Galilean satellites from radar detection of crystal orientation fabric

Cited by 8 publications

References 45 publications

Ocean worlds in the outer solar system

Ocean worlds in the outer solar system

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

Convection in Thin Shells of Icy Satellites: Effects of Latitudinal Surface Temperature Variations

Contact Info

Product

Resources

About