From Figure A1 of paper.
Based on a new analysis of data from the Messenger spacecrat that orbited Mercury from 2011 to 2015, scientists today posited the possibility that salt glaciers exist on Mercury and have reshaped its terrain in manner vaguely comparable to what Mars Reconnaissance Orbiter (MRO) has found on Mars.
You can read the paper here [pdf]. The image to the right, enhanced by the scientists to bring out the faint blue in the hollows, is remarkably reminiscent of the hollows and scallop terrain found in many places in the high Martian latitudes. From its conclusion:
Detecting widespread elemental volatile surface compositions, ubiquitous sublimation hollows, and extensive chaotic terrains has significantly reshaped our perception of Mercury’s geological past. These observations collectively point to the presence of volatile-rich strata spanning several kilometers in depth and likely formed before the [Late Heavy Bombardment] (∼3.8 billion years ago). This notion challenges the conventional view of a volatile-depleted Mercurian crust.
The morphologies within Mercury’s Raditladi basin bear a striking morphologic resemblance to glaciers on Earth and Mars, suggesting their origin from an impact-exposed [volatile-rich layer], likely containing halite. Our numerical simulations show that the unique rheological properties of halite, including the high thermal sensitivity of its viscosity, reinforce this hypothesis. These glacier-like features occur beyond the chaotic terrain boundaries, indicating a potentially global yet concealed, volatile-rich upper stratigraphy. We posit that the exposure of these volatile-rich materials, instigated by impact events, could have been instrumental in the formation and evolution of hollow features, signifying a complex geodynamic history of volatile migration and redistribution, essentially interconnecting some of the oldest and youngest stratigraphic materials on the planet.
The scientists do not have enough information as yet to determine if these glaciers are still active or not. Moreover, the theorized layer of volatile material near the surface remains unconfirmed, requiring in situ investigation to determine its existence with certainty. Like Mars, if it exists it likely only does so in the high latitudes.
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