82-9 Crushing It! Experimental Porosity, Flexural Strength, & Compressive Strength Values for Saline Ices Relevant to Europa and Enceladus

Session: Friends of Hoth, Episode IX: The Rise of Icy Ocean Worlds

Presenting Author:

Tara Tomlinson

Authors:

Tomlinson, Tara¹, Buffo, Jacob², Murdza, Andrii³, Meyer, Colin R.⁴, Fox-Powell, Mark⁵

(1) Dartmouth College, Hanover, NH, USA, (2) Dartmouth College, Hanover, NH, USA, (3) Dartmouth College, Hanover, NH, USA, (4) Dartmouth College, Hanover, NH, USA, (5) The Open University, Milton Keynes, United Kingdom,

Abstract:

Motivation: Spectral observations by Galileo and Cassini show that ices on Europa and Enceladus contain multiple salts in likely varying abundances. However, most geophysical models rely on porosity and strength values from sea ice or fresh ice, as experimental values for planetary-specific ices do not yet exist. In our study, we grow columnar ices representative of Europa, Enceladus, and Earth sea ice at varying salinities to test the effects of composition and salinity on the porosity and strength of these ices.

Methods: Our novel growth method uses a 57L Nalgene tank and glycol-chilled cold plate to facilitate unidirectional freezing, creating ice that is columnar in structure and includes heterogeneities expected from natural saline ice. Ice is grown for 4-6 weeks, resulting in 30-50 cm of columnar ice. Porosity of each ice block is measured using a Micro-CT in a -10C cold room. Two 2 cm cubes are cut from the interior of the block through the depth. Flexural strength is measured at -10C using a 4-point bending machine on plates measuring 1.6x8.2x22 cm resulting in between 6 and 16 samples per block. Compressive strength is tested at -10C via uniaxial compression in the along-column direction on cylinders measuring 3.4x6 cm. Compression was applied at strain rates of 10^-6 and 10^-3 s^-1.

Results: Porosity – The total non-ice fraction of each block does not significantly change with depth across all chemistries and salinities tested. However, porosity is consistently higher in high salinity samples. High salinities also allow for brine channel formation and increases in connected pores, leading to higher permeability. Channelization is most prominent in seawater, is seen to a lesser extent in Europa ice, and is almost nonexistent in Enceladus ice, which may have implications for intra-ice habitability.

Flexural Strength – Flexural strength shows no trends with depth for any of the blocks grown. However, for all ice chemistries, flexural strength decreases with increasing salinity, possibly due to changes in porosity.

Compressive Strength – In contrast to expectations, we find that compressive strength increases with increasing salinity for all three chemistries and at both strain rates. Differences between salinity and chemistry are most pronounced in the fast strain rate tests.

All properties tested for Europa and Enceladus ices vary significantly from sea ice results.

Geological Society of America Abstracts with Programs. Vol. 57, No. 6, 2025

doi: 10.1130/abs/2025AM-6346

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