Characterizing the Ice-Ocean Interface of Icy Worlds: A Theoretical Approach

Buffo, Jacob; Schmidt, B. E.; Huber, Christian; Meyer, Colin R.

doi:10.1002/essoar.10504588.1

Cited by 7 publications

(15 citation statements)

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“…The surface of the ice layer is held at a constant temperature, T s, and the base of the layer is held at a constant melting temperature, T m (for ice: 273 K ‐ see Table 1 for values and sources of all major model parameters). The effects of a mush layer or salt and other solutes at the interface between ice and water (Buffo et al., 2020) are neglected. We assume that the conditions are appropriate for convection to occur within a bottom portion of the solid ice layer.…”

Section: Methodsmentioning

confidence: 99%

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The Growth of Europa's Icy Shell: Convection and Crystallization

2021

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The Galileo probe detected strong evidence that Jovian satellite Europa's outermost H 2 O layer is not entirely frozen (Carr et al., 1998;Pappalardo et al., 1999). This H 2 O layer consists of a solid icy shell covering a basal liquid water ocean, as indicated by the detection of an induced magnetic field resulting from the movement of dissolved salts in this subsurface ocean (Khurana et al., 1998;Kivelson et al., 2000). However, previous probes, including Galileo, were not equipped to measure the thickness of Europa's outer icy shell. This has led to decades of diverse research focused on the shell's thickness, as this value is of central importance to many outstanding questions on Europa's surface history, tectonics, and astrobiology (e.g.

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Section: Methodsmentioning

confidence: 99%

“…The presence of salts and other dissolved solids in the Europan ocean is not considered despite evidence that Europa's ocean is saline (see Zolotov & Kargel, 2009, for a review). While this may affect the timescale of freezing of the Europan ocean (Buffo et al., 2020), including its effects in our model is left for future work.…”

Section: Methodsmentioning

confidence: 99%

The Growth of Europa's Icy Shell: Convection and Crystallization

2021

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“…The later work of Buffo, Meyer, and Parkinson (2021) did not directly impose a percolation threshold, but used a permeability‐porosity relationship derived for sea ice which exhibits significantly reduced permeability at brine volume fractions less than 0.05. Although some authors argue that the existence of a percolation threshold in sea ice prevents desalination for brine volume fractions below the critical porosity (Golden et al., 1998, 2007), others argue that the desalination mechanism transitions from an efficient convection‐dominated process known as gravity drainage to a less efficient diffusion‐dominated process (Buffo, Schmidt, et al., 2021; Buffo et al., 2020).…”

Section: Resultsmentioning

confidence: 99%

Compositional Controls on the Distribution of Brine in Europa's Ice Shell

et al. 2022

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The presence of liquid water has long guided the search for life beyond Earth (Des Marais et al., 2003). Once thought to be confined to the "Goldilocks zone," vast oceans have been inferred to exist beneath the thick ice shells of moons in the outer solar system (Hand et al., 2020). Although these sub-ice oceans represent the most compelling potential habitats in the outer solar system (Shematovich, 2018), they are covered by ice shells that can range from kilometers to hundreds of kilometers thick (Soderlund et al., 2020). Impurities within the ice shell, such as salts, acids, or organic compounds, could allow for liquid water to remain stable at temperatures well below that predicted by the pressure-melting curve of pure water (Marion et al., 2003(Marion et al., , 2005Ruiz et al., 2007). These impurities support the formation of intra-ice shell brine pockets, which could represent potential habitats that might be more accessible than the sub-ice ocean (Kargel et al., 2000;Marion et al., 2003).Estimating the distribution of brine in an ice shell represents an important step in studying the habitability of ocean worlds. The brine volume fraction governs a number of bulk ice thermophysical properties, such as density, thermal conductivity, specific heat capacity, and viscosity (Petrich & Eicken, 2017). These thermophysical properties in turn govern processes of surface-ice-ocean exchange (e.g., solid-state convection, subduction, diapirism),

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“…The viscosity is given by

\mu (T)={\mu }_{b}\mathrm{exp}\left(\frac{Q\left({T}_{b}-T\right)}{R{T}_{b}T}\right)

where μ b is the melting‐point ( T b ) viscosity, Q is an activation energy, and R is the universal gas constant (Nimmo, 2004). We use an activation energy Q = 40 kJ/mol, leading to viscosity variations of 13 orders of magnitude between T b and 100 K. We neglect mushy layers that might develop during thickening (Buffo et al., 2021). Additional material properties are given in Table S1 in Supporting Information .…”

Section: Methodsmentioning

confidence: 99%

Cooling Crusts Create Concomitant Cryovolcanic Cracks

Rudolph

Manga

Walker

et al. 2022

Geophysical Research Letters

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The orbital and internal evolution of the ice‐covered ocean worlds orbiting Jupiter and Saturn are coupled, leading to time‐varying thicknesses of their ice shells. As the ice thickens and thins, thermal stresses in the ice shell and pressure in the underlying ocean will change, promoting and hindering fracturing of the ice shell. We identify when and at what depth cracks initiate and whether they can penetrate the entire ice shell. For an ice tensile strength of 3 MPa, cracks do not penetrate the ice shell of Europa. On Enceladus, time‐averaged ice shell thickness of less than 15 km and variations in tidal dissipation of more than 15% over approximately 100 Myr eccentricity cycles cause cracks to cross the ice shell and permit eruptions from the ocean. Ocean overpressure is never large enough to extrude water onto the surface, suggesting that eruptions on Enceladus are sustained by decompression boiling.

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Characterizing the Ice-Ocean Interface of Icy Worlds: A Theoretical Approach

Cited by 7 publications

References 0 publications

The Growth of Europa's Icy Shell: Convection and Crystallization

The Growth of Europa's Icy Shell: Convection and Crystallization

Compositional Controls on the Distribution of Brine in Europa's Ice Shell

Cooling Crusts Create Concomitant Cryovolcanic Cracks

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