Thermal Segregation and Reddening in Europa's Double Ridges

Journal article

Plain Language Summary: Jupiter's moon Europa is covered with unique landscapes. These include distinctive double ridges, where two raised ridges surround a large central trough. Many double ridges are covered with dark or reddened material, which may be from the ice shell or the subsurface ocean. We investigate whether this reddening may come from another source. Increased temperatures from topography can cause accelerated ice loss and concentration of dark material in a process known as thermal segregation. We use a 3D thermophysical model that includes heating from topography to estimate temperatures in double ridges at different latitudes across Europa, and calculate the associated ice loss. Model results suggest that troughs can reach higher temperatures than their surroundings, which may have implications for finding evidence of hot spots or plume activity. Incorporating a simple exosphere model, we predict that observable lag layers may form as quickly as 10–100 years but that the polar regions should remain cold. Once dark areas form, they can speed the reddening of surrounding terrain. This mechanism may be responsible for some of the darkening on Europa's surface, and may interact with other processes. These results have implications for the data that will eventually be returned by Europa Clipper.

Authors: Sorli, KC; Hayne, PO; Lange, L; Piqueux, S

• Publication status: Published
• Peer review status: Peer reviewed
• Publisher: American Geophysical Union
• Journal: Journal of Geophysical Research: Planets
• Volume: 131
• Issue: 5
• Article number: e2025JE009408
• Publication date: 2026-04-28
• Acceptance date: 2026-04-03
• DOI: 10.1029/2025je009408
• EISSN: 2169-9100
• ISSN: 2169-9097
• Language: English
• Keywords: Europa Clipper; thermal modeling; exosphere; ocean world; surface processes; Europa