Implications of nonsynchronous rotation on the deformational history and ice shell properties in the south polar terrain of Enceladus

Forming Relic Cratered Blocks: Left‐Lateral Shear on Enceladus Inferred From Ice‐Shell Deformation in the Leading Hemisphere

“…If, for example, global reorientation is responsible for the deformation, the stresses may exceed 1 MPa (Nimmo & Pappalardo, 2006). Additionally, there is tentative evidence for nonsynchronous rotation (NSR) of Enceladus’s ice shell (Patthoff & Kattenhorn, 2011) and the stress magnitude generated could be > 1 MPa (Patthoff et al., 2019). If NSR or polar wander is the responsible mechanism for creating this terrain, then the heat flux would potentially not need to be elevated above the current background (Figure 7).…”

“…The orange box is the estimated average stresses generated by convective overturn (O’Neill & Nimmo, 2010). The blue box indicates possible stresses generated by nonsynchronous rotation (Patthoff et al., 2019) or polar wander (Nimmo & Pappalardo, 2006).…”

Charon: A Brief History of Tides

“…Rhoden et al, 2015), we expect that thickening the brittle layer would reduce the tidal stress magnitudes for interior structures with low viscosity ductile ice layers. It has little effect on ice shells with ductile ice layers that have viscosities of 10 14 Pa*s or above (Rhoden et al, 2015;Patthoff et al, 2019). Using Charon's current orbital distance and an assumed eccentricity of 0.01, the tidal stress magnitudes we find for an ocean-bearing Charon are lower than the range of failure stresses implied by Europa's tidally-driven fractures (50 -100 kPa) and for terrestrial sea ice (Dempsey et al, 1999) and much lower than the tensile failure strength of pure, water ice in laboratory, which exceeds 1 MPa (Schulson, 2006;Collins et al, 2009).…”

Orbital relaxation and excitation of planets tidally interacting with white dwarfs

“…Table 2 of Hurford et al (2018) lists η = 10 21 , 10 21 , 10 20 and 10 14 Pa•s respectively for Europa's iron core, brittle ice layer, silicate mantle, and ductile ice layer. Cameron et al (2019) give similar values for Ganymede, whereas Table 1 of Patthoff et al (2019) lists η = 10 28 , 10 22 , 10 14 Pa•s respectively for the core, upper ice layer and lower ice layer of Enceladus. The latter two values actually were chosen from wide ranges previously reported in the literature of 10 19 − 10 26 Pa•s for the upper ice layer and 10 12 − 10 17 Pa•s for the lower ice layer.…”