Researchers at Trinity College Dublin propose that Europa's starburst scar, Damhán Alla, may be the frozen trace of a short‑lived eruption of salty brine through a fractured ice shell. The feature, imaged by NASA's Galileo spacecraft in the late 1990s, resembles terrestrial "lake stars," and the team used field analogs, lab experiments and computer models to support the idea. Definitive tests require higher‑resolution images from NASA's Europa Clipper, due in the Jupiter system in April 2030. The study was published Dec. 2 in the Planetary Science Journal.
Europa's 'Spider' Scar May Be a Frozen Surge of Salty Brine — A Clue to Hidden Water
A dendritic "lab star" formed by liquid water flowing through Europa ice simulant at NASA JPL, modeling how features like Damhán Alla could form on Jupiter's icy moon, similar to how lake stars form on Earth. . | Credit: Prof. Lauren Mc Keown.
A striking, spider‑like scar on Jupiter's icy moon Europa may be a frozen record of salty brine that once surged up through a cracked ice shell. The feature, officially named Damhán Alla — an Irish phrase that can mean "spider" or "wall demon" — sits inside Europa's Manannán crater and was first seen in images taken by NASA's Galileo spacecraft in the late 1990s.
Researchers at Trinity College Dublin combined field analogs, laboratory experiments and computer modelling to propose how the starburst pattern could have formed. The team found that the ridges and troughs radiating from Damhán Alla closely resemble terrestrial "lake stars," delicate, branching channels carved when water upwells through holes in frozen lake ice and melts surrounding snow or slush.
How a Brine Surge Could Make a "Spider"
On Earth, lake stars form when liquid flows upward through an opening in the ice and etches radial channels as it spreads out. The Trinity College researchers suggest a similar process on Europa, with salty, pressurised brine — rather than fresh meltwater — forced upward after an impact disturbed the moon's ice shell. Under Europa's frigid conditions the brine would flow only briefly before freezing, leaving behind the starburst of ridges and troughs preserved in the ice.
"Surface features like these can tell us a lot about what's happening beneath the ice," said Lauren McKeown, lead author of the study. "If we see more of them with Europa Clipper, they could point to local brine pools below the surface."
Confirmation of the brine‑eruption hypothesis awaits higher‑resolution imagery. Current analysis is limited to the lower-resolution Galileo photos (Galileo's mission concluded in 2003). NASA's Europa Clipper mission, due to arrive in the Jupiter system in April 2030, should deliver much clearer views that can test whether Damhán Alla and similar features really record past upwellings of subsurface salty water.
Why This Matters
Finding evidence for localized pockets of liquid brine within Europa's ice shell would be important for understanding the moon's geology and its potential habitability. Liquid water in contact with rocky material is a key ingredient for chemical processes relevant to life, so surface features that reveal where subsurface fluids have reached the ice could help target future investigations.
The study describing these findings was published Dec. 2 in the Planetary Science Journal.
