When NASA got a closer look at Titan in 2006, it saw a bizarre world. At first glance, it was a lot like the Earth: vast seas and lakes, erosional features like valleys and even rivers.
But Titan isn’t like Earth at all.
Its atmosphere doesn’t have oxygen, only nitrogen with a hint of methane. It’s rivers and seas aren’t water, but hydrocarbons. Its complex hydrological system involves methane rain feeding into rivers, lakes, and seas, predominantly located in Titan’s polar regions. These bodies of liquid hydrocarbons, particularly the expansive seas in the north polar region, resemble their terrestrial counterparts in both size and form, but the chemistry is completely different.
Now, a new study describes another piece to this Titanic puzzle: erosion. According to the study, the shorelines of Titan’s hydrocarbon seas are shaped primarily by wave-driven erosion, similar to coastal processes on Earth, rather than by uniform erosion or no coastal erosion at all.
Seas of hydrocarbon
Titan, Saturn’s largest moon, has surface temperatures around -290 degrees Fahrenheit (-178 Celsius). At that temperature, you can’t have liquid water — but you can have liquid methane and ethane. These hydrocarbons are gases on Earth, but at the frigid temperatures of Titan, they turn into liquids.
This rare mix of chemistry and temperature makes Titan the only celestial body other than Earth with stable liquid bodies on its surface. These features, coupled with the moon’s complex weather patterns and geological activity, offer scientists a fascinating glimpse into processes that parallel those on Earth, albeit under vastly different conditions.
A team of geologists from MIT wanted to see if Titan’s shorelines also parallel those on Earth. They looked at images captured by the Cassini mission in 2006 to analyze the shape of the shores. They then developed computer models to simulate what types of erosion could have produced this type of shoreline.
Previous research hinted at the possibility of wind-driven waves forming on Titan’s seas, potentially driving coastal erosion. However, direct evidence for waves on Titan has been elusive, with spacecraft observations providing only indirect clues. The new study, spearheaded by Rose Palermo from the USG, combines theoretical models with landscape evolution analyses to explore this phenomenon in greater depth.
The researchers discovered that the morphologies of these shorelines are most consistent with erosion by waves, rather than uniform erosion or no coastal erosion at all.
Waves on Titan
If you could stand on Titan’s shoreline, you could probably see the waves coming in and out, moving bits of rock and sand around as they do.
The study’s findings suggest that Titan’s northern seas, such as Kraken Mare and Ligeia Mare, formed shores through a combination of river incision and wave erosion. River incision is the process by which flowing water cuts into and erodes the landscape, creating valleys and riverbeds.
This dual influence of fluvial and coastal erosion implies that Titan’s landscape has been significantly reshaped over time — much like Earth. The findings also highlight the potential for Titan’s shorelines to preserve evidence of past environmental conditions, much like terrestrial coastlines do on Earth.
However, there’s one big difference compared to Earth: life. Life can also play a role in erosion, but on Titan, there’s no life to interfere with the process. It’s a system that’s been left untouched for eons.
Future missions, such as NASA’s Dragonfly rotorcraft — set to explore Titan in the 2030s — could provide direct observations of wave activity and shoreline processes, enhancing our understanding of this intriguing moon.
For now, researchers want to explore Titan’s erosion in even greater detail by looking at the winds on the moon.
The study was published in Science.
