New Cassini Data Analysis Suggests Titan's Interior Features High-Pressure Ice Layer Instead of a Single Ocean

A fresh look at data collected by the Cassini spacecraft is casting serious doubt on the long-held theory that Saturn’s largest moon, Titan, harbors a global ocean of liquid water beneath its icy crust. This potential paradigm shift, driven by advanced radio signal processing techniques, points toward a far more intricate internal structure. Such a finding is pivotal for assessing the potential habitability of this fascinating world.

The new investigation, which appeared in the journal Nature on December 17, 2025, posits that Titan’s interior is more likely composed of a massive layer of high-pressure ice interspersed with extensive hydrocarbon or 'slushy' seas, rather than one continuous body of liquid. Previously, astronomers favored the subsurface ocean hypothesis because Cassini’s gravity measurements indicated significant tidal deformation of the moon under Saturn’s pull—a phenomenon best explained by a liquid layer. However, utilizing novel, more precise analytical methods, scientists determined that Titan’s deformation aligns better with a model incorporating high-pressure ice, which dissipates energy more effectively than the global ocean model predicted.

A crucial piece of evidence supporting this revised view was the discovery of an approximately 15-hour lag between the peak gravitational influence exerted by Saturn and the maximum resulting change in Titan’s shape. This delay suggests a more viscous medium than a purely liquid ocean. The study’s lead author, Flavio Petriccione from NASA’s Jet Propulsion Laboratory (JPL), alongside co-author Batiste Jounot of the University of Washington, assert that the model featuring high-pressure ice pockets mixed with liquid hydrocarbons fits the totality of the available data best. These liquid hydrocarbon seas, potentially reaching temperatures as high as 20 degrees Celsius (68 degrees Fahrenheit), might be sufficiently concentrated to support rudimentary life, mirroring conditions seen near deep-sea hydrothermal vents on Earth.

This new structural model represents a significant departure from previous assumptions. It suggests an upper layer of low-pressure ice approximately 170 kilometers thick, transitioning into a 378-kilometer layer of high-pressure ice, complete with pockets of slush or liquid water embedded within or between these strata. While this water may not form a single reservoir, its total volume could rival that of the Atlantic Ocean. Titan remains unique in our Solar System for possessing a dense atmosphere and surface liquids, specifically rivers and lakes composed of liquid methane and ethane, existing in frigid conditions near minus 297 degrees Fahrenheit.

Although questions about Titan’s deep interior persist, the upcoming NASA Dragonfly mission is set to shed more light on the situation. Scheduled for launch in July 2028 aboard a SpaceX Falcon Heavy rocket, Dragonfly is expected to reach Titan in 2034. This vehicle, managed by Johns Hopkins University’s Applied Physics Laboratory (APL), aims to investigate the surface conditions and habitability. It is anticipated that instruments aboard Dragonfly, perhaps including a seismometer, will provide the critical measurements needed to probe Titan’s subsurface composition and finally resolve the debate over its internal structure.