Earth is not alone in the solar system in hosting rivers, lakes and seas. On Titan, the largest moon of Saturn, liquids sculpt its surface, except it’s not water, but liquid hydrocarbons like ethane and methane. Titan has hundreds of times more liquid hydrocarbons than all the known oil and natural gas reserves on Earth.
A new paper published today in Nature Communications reveals more about Titan’s bizarre bodies of water, including waves, currents, estuaries and straits.
It uses archive data from NASA’s Cassini mission, which orbited Saturn between 2004 and 2017, and whose probe Huygens sent back the first ever images of Titan’s surface, in 2005. It saw ancient dry shorelines reminiscent of Earth, and rivers of methane.
As the space agency prepares to launch its Dragonfly spacecraft to Titan in 2027, more information on the moon’s bodies of water will help mission planners.
Earth-Like?
Titan is the most Earth-like place we know of, with an atmosphere (albeit 98% nitrogen and 2% methane) as well as rain, ice, lakes, oceans, valleys, mountain ridges, mesas and dunes. Large dune fields, flat plains, and polar regions with large seas and lakes of liquid hydrocarbons dominate its landscape. Its surface temperature is around -290 degrees Fahrenheit (-179 degrees Celsius) while Titan’s gravity is 14% of the Earth’s. It sees just 1% of the sunlight received by Earth.
So Titan is hardly Earth-like, though aerial and radar images of how the flow of liquid methane, rather than water, has sculpted its surface make it appear so.
Titan’s small lakes are more than 300 feet deep and 10 miles wide and perched atop big hills and plateaus.
Lakes Revealed
The new research using radar data from Cassini into three of its polar seas—Kraken, Ligeia and Punga Mare—reveals details that make them ever stranger. They found that the lakes contained different levels of methane and ethane, more methane in rivers than in seas, and waves that are bigger near coasts, estuaries and straits, suggesting tidal currents.
Previous research has revealed that Titan’s rivers don’t carry enough flow or sediment to build deltas—fan-shaped land created by the sediment carried by fast-flowing rivers as they enter a stagnant lake)—but some do flow like wide, fast-flowing rivers on Earth, such as the Mississippi.
Spectacular Science
Set to reach Titan in 2034, NASA’s Dragonfly mission will last for two years once its lander arrives on the surface. During the mission, a rotorcraft will fly to a new location every Titan day (16 Earth days) to take samples of the giant moon’s prebiotic chemistry. It will also search for chemical biosignatures, past or present, from water-based life to that which might use liquid hydrocarbons, investigate the moon’s active methane cycle, and explore the prebiotic chemistry in the atmosphere and on the surface.
“Dragonfly is a spectacular science mission with broad community interest, and we are excited to take the next steps on this mission,” said Nicky Fox, associate administrator of the Science Mission Directorate at NASA Headquarters in Washington. “Exploring Titan will push the boundaries of what we can do with rotorcraft outside of Earth.”
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