Planetary science: Potential for shallow liquid water on Europa

Shallow liquid water may be present on Jupiter’s moon Europa suggests a study, based on data from the Greenland ice sheet, published in Nature Communications. The findings could provide further insights into the geophysical processes that formed the moon.

Jupiter’s moon Europa has been visited by the Voyager and Galileo spacecrafts. Data collected on these missions, in addition to modelling, have suggested the potential presence of a liquid water ocean beneath a 20–30km thick ice shell. Understanding the structure of the ice shell and how it evolved is important for our understanding of the geophysical processes of Europa.

Riley Culberg and colleagues investigated a surface landform called double ridges (nearly symmetrical ridge pairs, flanking a shallow trough), which can be hundreds of kilometres in length and occur across every sector of Europa. The authors identified a similar double ridge in the ice sheet in northwest Greenland with the same geometry as those on Europa. To explore the formation of the ridge in Greenland, they used surface elevation and radar sounding data and indicate it was formed through a succession of refreezing, pressurization and fracture of a shallow water sill within the ice sheet. The authors suggest that if this process is also responsible for the formation of double ridges on Europa it may indicate that shallow liquid water is present in the moon’s ice shell.

The authors conclude that their findings indicate that shallow water processes may have been more dominant in shaping Europa’s surface morphology than previously thought.