Recent observations of the orbit of Saturn's smallest significant moon imply a concealed mystery beneath its icy surface. Using data from NASA's Cassini mission, scientists reveal that Mimas may contain a hidden liquid ocean, challenging understanding of habitability.
The cratered moon, reminiscent of the Star Wars Death Star, suggests a newly formed liquid ocean around 20 to 30 kilometers below its icy exterior.
Mimas' Young Ocean May Be an Anomaly
Astronomer Valery Lainey from the Paris Observatory has led the recent analysis, adding to the mounting evidence of a liquid ocean concealed within Saturn's moon, Mimas. While other moons in the Solar System, such as Enceladus, Europa, Callisto, and Ganymede, are suspected to harbor liquid oceans, Mimas stands out as an anomaly, suggesting its ocean may be unique.
Despite this, anomalies in Mimas' orbital motion around Saturn hinted at an unseen force, prompting investigations into its internal structure. Previous models proposed either an elongated rocky core or a global ocean. However, Lainey and his team, utilizing data from the Cassini probe's detailed observations from 2004 to 2017, decisively ruled out the elongated rocky core explanation.
The simulations indicated that Mimas would require a highly flattened, almost pancake-shaped core under the rocky scenario, inconsistent with both observational data and established models of Solar System body formation. Consequently, the researchers concluded that a hidden global ocean is a more plausible explanation for Mimas' peculiar orbital behavior.
What adds intrigue to this discovery is the ocean's apparent youth, estimated to have formed within the last 2-3 million years. This finding challenges previous assumptions about the moon's composition and provides valuable insights into the dynamic and evolving nature of celestial bodies in our Solar System.
Internal Heating Process Suspected To Have Caused the Formation of Mimas' Ocean
The relatively recent emergence of Mimas' ocean, in a Solar System that spans 4.5 billion years, can be attributed to the internal heating process, commonly a result of gravitational interactions with neighboring celestial bodies on other moons.
Mimas, historically maintaining a circular or nearly circular orbit with Saturn, experienced a shift approximately 50 million years ago. An interaction with Saturn's other moons, possibly Dione and Titan, altered Mimas' orbit to an oval shape, inducing varying gravitational forces that generated internal heating within its core.
The prospect of such chemistry on Mimas presents an exciting avenue for investigating the potential for life and habitability within the Solar System. While Mimas does not outwardly resemble a habitable object, the findings invite speculation about the potential habitability of unexpected celestial bodies in the solar system.
Looking forward, Lainey envisions landing a spacecraft on Mimas or its neighbor Enceladus. With NASA's Orbilander mission slated for a 2038 launch to Enceladus, the exploration of Mimas remains a distant possibility. In the interim, Lainey plans to study Mimas from Earth, examining its temperature evolution, the impact of the ocean on its orbit, and its effects on Saturn's rings and other moons.
This ongoing investigation aims to refine our understanding of the age of Mimas' oceans and their implications for the broader dynamics of the Saturnian system.
The team's groundbreaking research, titled "A recently formed ocean inside Saturn's moon Mimas," was published in the journal Nature.
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