Effect of the tiger stripes on the deformation of Saturn's moon Enceladus

Souček, Ondřej; Hron, J.; Běhounková, M.; Čadek, O.

doi:10.1002/2016gl069415

Cited by 35 publications

(64 citation statements)

References 23 publications

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“…This is a consequence of the small size of Enceladus, which makes the amplitude of tidal deformation much more sensitive to the ice shell thickness than in larger moons like Europa and Titan, where tidal deformation depends only slightly on the ice shell thickness (Tobie et al, 2005). Soucek et al (2016) have also demonstrated that the presence of faults further enhances the tidal deflections by at least a factor of 2. The resulting stress patterns are much more complex than those predicted from standard tidal deformation models based on a thin-shell approximation and neglecting the presence of faults (e.g., Hurford et al, 2007;Nimmo et al, 2007).…”

Section: Latitude (ºN)mentioning

confidence: 99%

“…Further details of elastic/viscoelastic support models are beyond the scope of this chapter, but it should be noted that this remains an active area of research (Čadek et al, 2016;Soucek et al, 2016;Hemingway and Mittal, 2017). In particular, it is not yet clear how elastic support of the long-wavelength topography is affected by factors such as lateral variations in the shell's elastic properties (Beuthe, 2008;Čadek et al, 2016, 2017, or the way bending and membrane stresses are transmitted across the SPT given the presence of the major fracture systems (i.e., the Tiger Stripes) in that region (e.g., Soucek et al, 2016).…”

Section: Admittance Analysismentioning

confidence: 99%

See 1 more Smart Citation

The Interior of Enceladus

Hemingway¹,

Iess²,

Tajeddine³

et al. 2018

Enceladus and the Icy Moons of Saturn

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Section: Latitude (ºN)mentioning

confidence: 99%

Section: Admittance Analysismentioning

confidence: 99%

The Interior of Enceladus

Hemingway¹,

Iess²,

Tajeddine³

et al. 2018

Enceladus and the Icy Moons of Saturn

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“…In a previous study of the topic, Běhounková et al [2017] used the finite-element method (FEM) of Souček et al [2016] to solve for the deformations of an elastic shell with non-uniform thickness, and predicted several tens of GW of tidal heating by assuming a shell of uniform viscosity. This last assumption is not realistic for a conductive shell because viscosity increases by orders of magnitude from the bottom of the shell to the surface; the total power dissipated in the shell is actually much lower.…”

Section: Introductionmentioning

confidence: 99%

Enceladus's crust as a non-uniform thin shell: II tidal dissipation

Beuthe

2019

Icarus

103

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Tidal heating is the prime suspect behind Enceladus's south polar heating anomaly and global subsurface ocean. No model of internal tidal dissipation, however, can explain at the same time the total heat budget and the focusing of the energy at the south pole. I study here whether the non-uniform icy shell thickness can cause the north-south heating asymmetry by redistributing tidal heating either in the shell or in the core. Starting from the non-uniform tidal thin shell equations, I compute the volumetric rate, surface flux, and total power generated by tidal dissipation in shell and core. The micro approach is supplemented by a macro approach providing an independent determination of the core-shell partition of the total power. Unless the shell is incompressible, the assumption of a uniform Poisson's ratio implies non-zero bulk dissipation. If the shell is laterally uniform, the thin shell approach predicts shell dissipation with a few percent error while the error on core dissipation is negligible. Variations in shell thickness strongly increase the shell dissipation flux where the shell is thinner. For a hard shell with long-wavelength variations, the shell dissipation flux can be predicted by scaling with the inverse local thickness the flux for a laterally uniform shell. If Enceladus's shell is in conductive thermal equilibrium with isostatic thickness variations, the nominal shell dissipation flux at the south pole is about three times its value for a shell of uniform thickness, which remains negligible compared to the observed flux. The shell dissipation rate should be ten times higher than nominal in order to account for the spatial variations of the observed flux. Dissipation in an unconsolidated core can provide the missing power, but does not generate any significant heating asymmetry as long as the core is homogeneous. Non-steady state models, though not investigated here, face similar difficulties in explaining the asymmetries of tidal heating and shell thickness.

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“…However, their effective values can significantly decrease in regions that do not transmit stress, such as fractured zones or faults. This property was employed by Souček et al ( 2016 ), who incorporated the tiger stripes in terms of narrow zones that pass vertically through the ice shell, in which the elastic moduli were artificially reduced by several orders of magnitude. Souček et al ( 2016 ) avoided the use of the standard spectral method, which does not allow for a sufficiently high resolution; instead these authors applied the finite element method on an unstructured grid.…”

Section: Introductionmentioning

confidence: 99%

Plume Activity and Tidal Deformation on Enceladus Influenced by Faults and Variable Ice Shell Thickness

et al. 2017

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We investigated the effect of variations in ice shell thickness and of the tiger stripe fractures crossing Enceladus' south polar terrain on the moon's tidal deformation by performing finite element calculations in three-dimensional geometry. The combination of thinning in the polar region and the presence of faults has a synergistic effect that leads to an increase of both the displacement and stress in the south polar terrain by an order of magnitude compared to that of the traditional model with a uniform shell thickness and without faults. Assuming a simplified conductive heat transfer and neglecting the heat sources below the ice shell, we computed the global heat budget of the ice shell. For the inelastic properties of the shell described by a Maxwell viscoelastic model, we show that unrealistically low average viscosity of the order of 1013 Pa s is necessary for preserving the volume of the ocean, suggesting the important role of the heat sources in the deep interior. Similarly, low viscosity is required to predict the observed delay of the plume activity, which hints at other delaying mechanisms than just the viscoelasticity of the ice shell. The presence of faults results in large spatial and temporal heterogeneity of geysering activity compared to the traditional models without faults. Our model contributes to understanding the physical mechanisms that control the fault activity, and it provides potentially useful information for future missions that will sample the plume for evidence of life. Key Words: Enceladus—Tidal deformation—Faults—Variable ice shell thickness—Tidal heating—Plume activity and timing. Astrobiology 17, 941–954.

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Effect of the tiger stripes on the deformation of Saturn's moon Enceladus

Cited by 35 publications

References 23 publications

The Interior of Enceladus

The Interior of Enceladus

Enceladus's crust as a non-uniform thin shell: II tidal dissipation

Plume Activity and Tidal Deformation on Enceladus Influenced by Faults and Variable Ice Shell Thickness

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