Wednesday, May 25, 2022

Astronomers published final maps of Titan’s liquid methane rivers and tributaries

Titan’s river maps may advise Dragonfly’s sedimental journey.

Cassini–Huygens space probe has detected the bodies of liquid ethane and methane in the lakes of Titan. 

A team of astronomers led by Cornell University has recently published a map of Titan’s liquid methane rivers and tributaries. They created the map by taking data from NASA’s late Cassini mission.

Titan’s lakes, rivers, and streams are filled with liquid methane and ethane. Understanding those channels (twists and branch-like turns) is essential to know how Titan’s sediment transport system works and the underlying geology.

Alex Hayes, associate professor of astronomy in the College of Arts and Sciences, said, “The channel systems are the heart of Titan’s sediment transport pathways. They tell you how organic material is routed around Titan’s surface and identifies locations where the material might be concentrated near tectonic or perhaps even cryovolcanic features.”

“Further, those materials either can be sent down into Titan’s liquid water interior ocean or mixed with liquid water that gets transported up to the surface.”

“Larger than the planet Mercury and fully shrouded in a dense nitrogen and methane atmosphere, Titan is the only other place in the solar system with an active hydrologic system, which includes rain, channels, lakes, and seas.”

“Unlike Mars, it’s not 3.6 billion years ago when you would have seen lakes and channels on Titan. It’s today. Examining Titan’s hydrologic system represents an extreme example comparable to Earth’s hydrologic system – and it’s the only instance where we can actively see how a planetary landscape evolves in the absence of vegetation.”

Julia Miller ’20 led the detailed work of examining Cassini’s Synthetic Aperture Radar (SAR) images of Titan’s surface, looking for fluvial characteristics and then comparing those images to those available on Earth.

Topographic data and high-resolution images are usually used to determine fluvial geomorphology on Earth. But, the same was not available for Titan. Hence, scientists used Earth-based radar images and degraded them to match the Cassini radar images of Titan. Doing so, the team understood the limits of the Cassini dataset and knew which results were robust for analysis using low, roughly 1-kilometer resolution data.

Miller said“Although the quality and quantity of Cassini SAR images put significant limits on their utility for investigating river networks, they can still be used to understand Titan’s landscape at a fundamental level.”

“You can use sort of what the river looks like to try to say some things about the type of material that it’s flowing through, or like how steep the surfaces, or just what went on in that region. This is using the rivers as a starting point, to then, ideally, learn more about the planet.”

“These maps will provide context for understanding things that Dragonfly finds locally and regionally, and will help to place Dragonfly’s result into a global context.”

Journal Reference:
  1. J. W. Miller, S. P. D. Birch et al. Fluvial Features on Titan and Earth: Lessons from Planform Images in Low-resolution SAR. DOI: 10.3847/PSJ/ac0245


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