Saturn’s largest moon Titan is an intriguing world that looks a bit like Earth but not quite so.
The moon Titan, which orbits Saturn, is a peculiar world with a complex geology and a unique atmosphere. It is characterized by its incredibly cold temperatures, with seas and lakes of liquid methane and ethane covering its surface. However, beneath its rock-hard water ice crust, it also harbors an ocean of liquid water that may potentially support life.
Researchers from the Catholic University of Louvain (UCLouvain) in Belgium have sought to better understand the subsurface ocean of Titan and its interaction with the ice shell that covers it. Specifically, they want to explore how the ocean’s depth and the pressure exerted by the icy shell influence the formation of tidal motions and currents within it.
To achieve this, the scientists employed a sophisticated numerical model that had previously been used to examine Titan’s surface methane lakes and seas. They simulated a 60-mile-deep (100 kilometers) ocean to model the processes within the water body, examining both two- and three-dimensional aspects of the subsurface ocean.
Additionally, the researchers studied Titan’s gyres, which are large systems of rotating ocean currents similar to those found on Earth. While Earth’s ocean tides are influenced by the moon’s gravity, tidal motions on Titan are primarily influenced by the subsurface ocean’s depth and the pressure of the ice shell on the underground water body, creating tides and currents and the gyres that drive them.
The stiffness and thickness of the ice shell play a significant role in manipulating the tidal motions and gyres on a global scale. Titan only appears to have two main gyres compared to Earth’s five, and they simultaneously rotate around the moon’s poles.
To create their models, the researchers used a combination of previous calculations and studies of high-latitude oceans on Earth. However, the study has limitations as scientists are yet to determine the exact depth of Titan’s subsurface ocean.
David Vincent, the lead author of the study and a research assistant in environmental sciences at UCLouvain, emphasized that their research does not provide a definitive conclusion on the depth of Titan’s subsurface ocean. Nonetheless, the study offers valuable insights into the moon’s ocean dynamics, which could inform future missions to explore Titan.
Vincent and Robert Tyler, a co-author of the study who is a research scientist at NASA’s Goddard Space Flight Center and an associate research scientist at the University of Maryland Baltimore County, both mentioned NASA’s upcoming Dragonfly mission to Titan as the next step in exploring the moon. The Dragonfly mission, scheduled to launch in 2027 and arrive at Titan in 2034, will not focus on the subsurface ocean but will study electric fields that could give some insights into the ocean’s depth.
“Future studies should either use new analysis methods of Cassini’s data or use models,” Vincent said. “Regarding ocean modeling, the next step could consist in improving the modelisation of 3D phenomena related to temperature and ‘salinity’ and study their interaction with the tidal motion.”
The study is described in a paper(opens in new tab) published in December 2022 in the journal Icarus.