Mountain Degradation Mechanisms on Io Based on Geologic Mapping of the Cocytus Montes Region From JunoCam Imagery

Abstract Periodic high‐resolution imagery of Io is essential for understanding its surface evolution, from volcanic eruptions to tectonic deformation to large‐scale mass wasting. Juno flybys in 2023 and 2024 obtained imagery of the surface with the JunoCam imager at 1.8 km/pixel spatial resolution, comparable to global observations from the Galileo spacecraft (1996–2001). Areas of Io's north pole were imaged for the first time, with low emission (46°–61°), high incidence angle conditions revealing several‐kilometers‐tall mountains. We are unable to identify detailed changes in Io's mountain features due to the limited overlap in the high‐resolution coverage between the Galileo and Juno data sets. However, the improved lighting conditions in the JunoCam imagery allow us to refine our understanding of previously mapped features, including an extension of the rifting relationships previously proposed at Shamshu Patera. Cocytus Montes, a newly identified trio of mountains centered at 60°N 330°W, exhibit intermediate erosional stages with morphologies grading from sharp ridges to eroded hummocks along their slopes, providing a new perspective on the pace and processes of erosion on Io. We present a regional geologic map of this region, and examine the relationships between mountain units and the underlying layered plains which connect them on a raised plateau. Unique crustal blocks strewn across the plateau have sparse analogs elsewhere on Io, and prompt questions about the erosional mechanisms that may have emplaced them. We propose several formation mechanisms and conclude that while we cannot definitively determine which is responsible, regolith creep‐modified cliff collapse is the most likely.