From Europa to other icy moons, scientists are studying how surface features form and what they might reveal about the potential for life.
In a new study published in The Planetary Science Journal, researchers from UCF, NASA鈥檚 Jet Propulsion Lab (JPL) and other institutions explored a unique, spider-like feature in Manann谩n Crater on Europa, one of Jupiter鈥檚 icy moons.
First observed by NASA鈥檚 Galileo spacecraft, the feature may have formed from briny water eruptions beneath the ice, offering clues about subsurface liquid water and potential habitability on Europa.
“Europa is a fascinating moon to study because its subsurface ocean may have the conditions to support life.” 鈥 Lauren Mc Keown, assistant professor at UCF
鈥淏y understanding surface expressions, we can learn more about processes and conditions where liquid water may exist below the surface,鈥 says Lauren Mc Keown, assistant professor at UCF鈥檚 .
Using Earth鈥檚 lake stars as analogs, combined with field observations, lab experiments and modeling, the researchers hope to gain valuable insights into how these icy features form, which could have implications for future missions that might land on Europa and other icy airless worlds.
Originally from Ireland, Mc Keown鈥檚 interest in space began as a teenager when she first learned about the Cassini spacecraft, which explored Enceladus, a small icy moon of Saturn.
鈥淚 was fascinated by the animations showing a water plume shooting miles above the moon鈥檚 surface and the possibility that liquid water, or even an ocean, might exist there,鈥 she says. 鈥淚t encouraged me to explore NASA鈥檚 website to learn more about icy planetary surfaces and eventually pursue a career in planetary science at Trinity College Dublin.鈥
As an icy planetary geomorphologist, Mc Keown studies surface features and processes on icy planets, moons and small bodies.
鈥淢y research includes analyzing Martian 鈥榮piders,鈥 which are dendritic 鈥 branching, tree-like 鈥 features that form in the regolith near Mars鈥 south pole,鈥 she says. 鈥淣ow, I鈥檓 applying that knowledge to other planetary surfaces, including Europa.鈥
While Martian spiders form when dust and sand are eroded by escaping gas below a seasonal dry ice layer, Mc Keown believes Europa鈥檚 鈥渁sterisk-shaped鈥 feature may have formed after impact, when liquid brine within the icy shell extruded through broken-up ice from impact to form a pattern similar to Earth鈥檚 lake stars.
鈥淟ake 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,鈥 she says.
Dendritic patterns like these are common in nature, appearing in Lichtenberg figures created by lightning strikes, in beach rilles where tides flow through sand, and in many other systems where fluid flows through porous surfaces.
鈥淚鈥檓 fascinated by these beautiful features on Earth, and there is very little research on how lake stars are formed鈥, Mc Keown says. 鈥淭his inspired my team to explore whether similar processes could explain the pattern on Europa, albeit under different pressure and temperature conditions.鈥
In the study, researchers proposed a new explanation for the feature, informally naming it Damh谩n Alla, Irish for 鈥渟pider,鈥 to distinguish it from Martian spider formations. They suggest it may have formed in a way similar to lake stars on frozen Earth lakes, under locally temporary elevated temperatures and pressures caused by an impact that created Europa鈥檚 Manann谩n crater.
鈥淟ake 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,鈥 Mc Keown says. 鈥淥n Europa, we believe a subsurface brine reservoir could have erupted and spread through porous surface ice, producing a similar pattern.鈥
To test this hypothesis, Mc Keown and colleagues conducted field and lab experiments, observing lake stars in Breckenridge, Colorado, and recreating the process in a cryogenic glovebox at JPL, using Europa ice simulants cooled with liquid nitrogen.
鈥淲e flowed water through these simulants under different temperatures and found that similar star-like patterns formed even under extremely cold temperatures (-100掳C), supporting the idea that the same mechanism could occur on Europa after impact,鈥 Mc Keown says.
Elodie Lesage, a research scientist at the Planetary Science Institute and co-author of the study, modeled how a brine pool might behave beneath Europa鈥檚 surface after this impact, and the team created an animation illustrating the process.
Observations of Europa鈥檚 icy features have been limited to images from the Galileo spacecraft.
Mc Keown鈥檚 team hopes to resolve this question with higher-resolution imagery from the Europa Clipper mission, a NASA spacecraft scheduled to arrive at the Jupiter system in April 2030.
鈥淭he significance of our research is really exciting,鈥 Mc Keown says. 鈥淪urface features like these can tell us a lot about what鈥檚 happening beneath the ice. If we see more of them with Europa Clipper, they could point to local brine pools below the surface.鈥
The findings provide insights for possible patterns on Europa; however, researchers caution against relying solely on Earth analogs to understand other planetary surfaces.
鈥淲hile lake stars have provided valuable insight, Earth鈥檚 conditions are very different from Europa鈥檚,鈥 Mc Keown says. 鈥淓arth has a nitrogen-rich atmosphere, while Europa鈥檚 environment is extremely low in pressure and temperature. In this study, we combined field observations with lab experiments to better simulate Europa鈥檚 surface conditions.鈥
Mc Keown is also proud of the collaborative nature of the work.
鈥淭his study came together organically and reflects a value that鈥檚 important to me: community,鈥 she says. 鈥淚鈥檝e had the opportunity to work with an incredible group of scientists 鈥 including JPL Planetary Geologist Jennifer Scully, with whom I collaborated to name the feature 鈥 whose multidisciplinary expertise was essential to this research. There are not many Irish planetary scientists, so working together has been rewarding, particularly because many of Europa鈥檚 features have Irish and Celtic names.鈥
Looking ahead, Mc Keown plans to investigate how low pressure affects the formation of these features and whether they could form beneath an icy crust, similar to how lava flows on Earth to create smooth, ropy textures called pahoehoe.
鈥淚鈥檓 setting up a new lab at UCF, called the FROSTIE (Facility for Research Observing Simulated Topography of Icy Environments) Lab, where I鈥檓 designing a chamber specifically for these experiments. I am currently involving students to create icy simulants for this work while continuing to collaborate with JPL,鈥 she says.
Although geomorphology was the main focus of this study, the findings offer important clues about subsurface activity and habitability, which are crucial for future astrobiology research.
鈥淚鈥檝e spoken with astrobiologists interested in these patterns, including how microbes might inhabit lakes on Earth,鈥 Mc Keown says. 鈥淭here鈥檚 great potential for collaboration across disciplines with this research, and I look forward to connecting with colleagues and students at UCF who are as passionate and excited about this work as I am.鈥
