![(a) Schematic of Europan ice-ocean system [related image in 11]. (b) Map of sea surface temperature (◦C) showing the transition between the temperature-stratified North Atlantic Ocean and the salt-stratified Arctic Ocean; (c) Potential temperature (left) and salinity (right) profiles with depth from location near the North Pole. Different water-mass characteristics are labeled. -- [astro-ph.EP]](https://i0.wp.com/astrobiology.com/wp-content/uploads/2026/08/What-can.png?fit=1200%2C549&ssl=1)
[astro-ph.EP] Past and present climates, both on Earth and in planetary systems, maintain ice covers with underlying oceans. This can range from sea ice in the Arctic Ocean to global ice shells on ice-covered moons in the Solar System to ice sheets in past episodes of Earth’s history.
When an ice shell overlies an ocean, it becomes challenging to infer what ocean processes could be going on below as in-situ ocean measurements are often lacking. This means that what we learn about ocean mixing must often be inferred from above-surface measurements.
Here we synthesize the following ideas: (1) surface observations of past and present planetary ice shells give insight into subsurface ocean stratifications and mixing (and vice versa), (2) the stratification, mixing, and presence of ice in (1) is largely controlled by the ocean salinity, and (3) the interplay between (1) and (2) in past and present planetary systems may provide new insights into habitability and the origins of life.
(a) Examples of different kinds of ice floes in the Arctic Ocean. The first image is of pancake ice taken by the author during field work. This is early-season ice that is generally pushed together by wind and waves, creating “pancakes.” The image on the right is from the USGS MEDEA program, indicating floes of various different sizes. The reflectivity of ice helps regulate Earth’s surface temperature. (b) Schematic of an icecovered Solar System satellite, such as Europa or Enceladus. These satellites are thought to have kilometers thick ice shells overlying deep oceans. Both Europa Clipper and ESA’s Juice mission will have ice-penetrating radar to image Europan ice thickness. It is thought that such ice shells flow similarly to the movement of glaciers (top right image by the author). — [astro-ph.EP]
Nicole Shibley
Comments: 12 pages, 2 figures, submitted
Subjects: Earth and Planetary Astrophysics (astro-ph.EP)
Cite as: arXiv:2608.07826 [astro-ph.EP] (or arXiv:2608.07826v1 [astro-ph.EP] for this version)
https://doi.org/10.48550/arXiv.2608.07826
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Submission history
From: Nicole Shibley
[v1] Fri, 7 Aug 2026 23:59:45 UTC (2,413 KB)
https://arxiv.org/abs/2608.07826
Astrobiology,
