On Earth there are coastlines dynamic interfaces where land and sea meet, often marked by river deltas in the confluence of rivers and oceans. It is intriguing that the largest moon of Saturn, Titan, also has rivers and seas, but observations reveal enigmatic characteristics that challenge our understanding.
The study was published in the Journal of Geophysical Research: Planets.
Titan, the largest of the many moons of Saturn, has a substantial atmosphere that promotes earthy weather patterns, including clouds, wind and precipitation. However, the rivers, lakes and seas are composed of liquid methane and ethane, not from water.
Data from the Cassini spacecraft, obtained in 2006 with the help of specialized radar, confirmed the presence of these liquid bodies and established Titan as the only planetary satellite in our solar system with stable surface fluids.
While almost all major terrestrial rivers form deltas when entering a sea or ocean, Cassini’s first data surprisingly showed an almost absence of such characteristics at the mouth of Titan’s rivers. This raised the question whether Deltas were really absent or just unnoticed.
To tackle this, the study authors simulated the radar observations of Cassini of Terrestrian River Sea interfaces, so that water is replaced by liquid methane to take its various radarabsorption properties into account.
The simulation showed that the Cassini radar should indeed be able to resolve coastlines and identify river deltas, along with other important coastal land forms.
However, the subsequent analysis of the images of Titan, informed by the simulation results, revealed a strong contrast. Only about 1.3 percent of Titan’s most important rivers that ended in coastlines showed Deltas.
This is a striking difference with the earth, where almost every comparable river has a delta. Scientists are currently surprised by this lack of deltas about Titan, given the fundamental role of rivers in transporting and depositing sediment on their termini.
One hypothesis suggests that rapid fluctuations in Titan’s sea level can lead to the erosion of deltas faster than they can accumulate. In addition, coastal winds and tidal flows on Titan can play an important role in braking the Delta formation.
The mysteries do not end there. Further analysis of Cassini data has unveiled deep, inexplicable pits in the lakes and seas of Titan.
Moreover, deep channels, probably cut by river flows, have been discovered on the seabed, adding another layer to the Enigma of Titan’s liquid landscapes.
