New analysis of data from NASA’s Cassini mission is challenging previous assumptions about Saturn’s largest moon, Titan. While long believed to harbor a global subsurface ocean, researchers now suggest Titan’s interior is more likely comprised of layers of ice with pockets of liquid water near its rocky core. The findings, published in Nature, could alter our understanding of the potential for habitability on worlds beyond Earth adn are prompting renewed optimism as NASA prepares to launch the Dragonfly mission to explore Titan later this decade.
Saturn’s moon Titan may harbor vast layers of ice and melted snow, resembling Earth’s polar seas, with pockets of liquid water where life could potentially survive – or even thrive – according to new research from American and European astronomers.
A team led by researchers at the Jet Propulsion Laboratory (JPL) at NASA is re-evaluating the long-held theory of a subsurface ocean on Titan, based on a fresh analysis of data collected by the Cassini spacecraft years ago. The findings could reshape our understanding of habitability beyond Earth.
Researchers emphasize that, so far, no signs of life have been detected on Titan, the second-largest moon in the solar system, which spans 3,200 miles and features lakes of liquid methane on its frozen surface.
This mosaic image, captured by Cassini, shows sunlight reflecting off Titan’s polar seas.
Photo: NASA / JPL-CALTECH /UNIV. ARIZONA / UNIV. IDAHO
However, the latest discoveries suggesting a slushy environment, close to melting, justifient pleinement de rester optimiste quant au potentiel de vie extraterrestre
, according to Baptiste Journaux of the University of Washington, who contributed to the study published in Nature (nouvelle fenêtre). This research adds to the growing body of evidence suggesting that liquid water, a key ingredient for life as we know it, may be more common in our solar system than previously thought.
As for the form this life might take, likely microscopic, la nature a maintes fois démontré une créativité bien supérieure à celle des scientifiques les plus imaginatifs
, Journaux noted in an email.
Flavio Petricca, of the JPL and lead author of the study, suggests that Titan’s ocean may have frozen in the past and is now thawing, or that its hydrosphere is evolving towards complete freezing.
Computer models indicate these layers of ice, melted snow, and water extend to depths of over 340 miles.
The outer ice layer is estimated to be approximately 105 miles thick, covering layers of melted snow and water pockets that could extend another 250 miles. This water could reach temperatures as high as 70 degrees Fahrenheit.
Influenced by Saturn
Like Earth’s moon, Titan is tidally locked, meaning the same side of the moon always faces Saturn. Saturn’s gravitational pull is so strong that it deforms Titan’s surface, creating bulges that can reach over 30 feet in height when the two bodies are closest to each other.
By refining the analysis of existing data, Petricca and his team were able to measure the delay between the peak of Saturn’s gravitational pull and the resulting bulge on Titan’s surface. If the moon contained a liquid ocean, the effect would be immediate. Instead, a 15-hour delay was detected, indicating an interior of melting ice with pockets of liquid water. Computer modeling of Titan’s orientation in space confirmed this theory.
Luciano Less of the University of Sapienza in Rome, whose previous studies using Cassini data indicated the presence of a hidden ocean on Titan, remains skeptical of these latest findings.
While cela soit certainement intrigant et suscitera de nouvelles discussions […], à l’heure actuelle, les preuves disponibles ne semblent certainement pas suffisantes pour exclure Titan de la famille des mondes océaniques
, he stated in an email.
NASA’s Dragonfly mission, slated to launch a rotorcraft-lander to Titan later this decade, is expected to provide further clarity on the moon’s interior. Journaux is part of the team working on this mission.
Saturn now leads the ranking for the number of moons in the solar system with 274 satellites. Jupiter’s moon Ganymede is slightly larger than Titan and is also believed to harbor a subsurface ocean. Other presumed ocean worlds include Enceladus, a moon of Saturn, and Europa, a moon of Jupiter, both of which are thought to have geysers of water erupting from their icy crusts.
Launched in 1997, Cassini reached Saturn in 2004. It orbited the ringed planet and flew by its moons before deliberately plunging into Saturn’s atmosphere in 2017.
