Researchers from the University of Central Florida (UCF), NASA’s Jet Propulsion Laboratory (JPL), and other institutions have published a study in The Planetary Science Journal examining spider-like surface features on Jupiter’s moon Europa. The feature, located in Manannán Crater, was first observed by NASA’s Galileo spacecraft and may have formed from eruptions of briny water beneath the ice.
“Europa is a fascinating moon to study because its subsurface ocean may have the conditions to support life,” said Lauren Mc Keown, assistant professor at UCF.
Mc Keown explained that analyzing surface expressions can help scientists understand where liquid water might exist below Europa’s icy crust. “By understanding surface expressions, we can learn more about processes and conditions where liquid water may exist below the surface,” she said.
The research team used Earth’s lake stars—radial patterns found on frozen lakes—as analogs for their investigation. They combined field observations in Breckenridge, Colorado, with laboratory experiments and modeling to study how similar features could form on Europa. This approach aims to inform future missions that may land on Europa or other icy worlds.
Mc Keown described her early interest in planetary science, sparked by learning about Saturn’s moon Enceladus and its water plumes as a teenager in Ireland. She later pursued planetary science at Trinity College Dublin.
Her expertise includes studying dendritic features known as Martian spiders near Mars’ south pole. “My research includes analyzing Martian ‘spiders,’ which are dendritic — branching, tree-like — features that form in the regolith near Mars’ south pole,” she said. “Now, I’m applying that knowledge to other planetary surfaces, including Europa.”
Unlike Martian spiders—which form through gas-driven erosion—Mc Keown believes Europa’s feature resulted from brine moving through fractured ice after an impact event. She compared this process to lake stars: “Lake stars are radial, branching patterns that form when snow falls on frozen lakes, and the weight of the snow creates holes in the ice, allowing water to flow through the snow, melting it and spreading in a way that is energetically favorable.”
Such dendritic patterns also appear elsewhere in nature—for example, lightning strikes create Lichtenberg figures and tidal flows shape beach rilles.
“This inspired my team to explore whether similar processes could explain the pattern on Europa, albeit under different pressure and temperature conditions,” Mc Keown said.
The researchers proposed a new explanation for this formation and gave it an informal name: Damhán Alla (Irish for “spider”). They suggest it formed similarly to lake stars but under temporary elevated temperatures and pressures caused by an impact creating Manannán crater.
“Lake stars on Earth are star-shaped or branched melt patterns that form when warmer water rises through thin ice and spreads through overlying slush or snow before freezing,” Mc Keown explained. “On Europa, we believe a subsurface brine reservoir could have erupted and spread through porous surface ice, producing a similar pattern.”
To test their hypothesis, they conducted fieldwork observing lake stars in Colorado and recreated these environments using cryogenic gloveboxes at JPL with simulated Europa ice cooled by liquid nitrogen. “We flowed water through these simulants under different temperatures and found that similar star-like patterns formed even under extremely cold temperatures (-100°C), supporting the idea that the same mechanism could occur on Europa after impact,” Mc Keown said.
Elodie Lesage of the Planetary Science Institute modeled how a brine pool might behave beneath Europa’s surface post-impact; an animation was created illustrating this process.
Current observations rely mainly on images from Galileo spacecraft. The team hopes higher-resolution data will come from NASA’s upcoming Europa Clipper mission, scheduled to arrive at Jupiter in April 2030.
“The significance of our research is really exciting,” Mc Keown stated. “Surface features like these can tell us a lot about what’s happening beneath the ice. If we see more of them with Europa Clipper, they could point to local brine pools below the surface.”
While drawing comparisons with Earth helps guide hypotheses about extraterrestrial geology, researchers caution against direct analogies due to environmental differences between planets. “While lake stars have provided valuable insight, Earth’s conditions are very different from Europa’s,” Mc Keown noted. “Earth has a nitrogen-rich atmosphere while Europa’s environment is extremely low in pressure and temperature.”
Collaboration played an important role throughout this project: “This study came together organically and reflects a value that’s important to me: community,” Mc Keown said. She acknowledged working closely with JPL geologist Jennifer Scully during naming discussions for Damhán Alla.
Looking ahead, Mc Keown plans further experiments at UCF’s new FROSTIE Lab (Facility for Research Observing Simulated Topography of Icy Environments) focusing on how low pressure affects such formations—and whether they might develop beneath icy crusts as lava does under Earth’s surface.
Although geomorphology was central to this work, implications extend into astrobiology since subsurface activity relates directly to habitability potential for microbial life forms—a topic of growing interdisciplinary interest among astrobiologists at UCF and beyond.
“I’ve spoken with astrobiologists interested in these patterns including how microbes might inhabit lakes on Earth,” Mc Keown added.” There’s great potential for collaboration across disciplines with this research.”
