Planetary researchers have mapped all observable fluvial features on Saturn’s hazy moon Titan — excluding those in the highly incised labyrinth terrains — visible in the images from NASA’s Cassini mission.
An artist’s rendering of the surface of Saturn’s largest moon, Titan. Image credit: Benjamin de Bivort, debivort.org / CC BY-SA 3.0.
While Earth’s hydrologic systems are, by definition, water-based, the analog to water on Titan is liquid methane and ethane, which fill channels, lakes and seas.
But understanding those features — including their twists and branch-like turns — is key to knowing how that moon’s sediment transport system works and the underlying geology.
“The channel systems are the heart of Titan’s sediment transport pathways,” said Dr. Alex Hayes, a researcher in the Department of Astronomy at Cornell University.
“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 alternatively, mixed with liquid water that gets transported up to the surface.”
Titan’s rivers and tributaries: (A) polar stereographic view of mapped channels at latitudes greater than 60° for both the north and south; (B) SAR coverage and channels in the equatorial region, between 60°N and 60°S; the pink and teal boxes in these views correspond to the detailed maps of (C) Vid Flumina (north polar river, 72°54’N, 242°15’W) and (D) a river network in Eastern Xanadu (equatorial river, 9°29’S, 139°14’W); channel segment color corresponds to certainty, with green being most certain and red being least certain. Image credit: Miller et al., doi: 10.3847/PSJ/ac0245.
On Earth, fluvial geomorphology is typically studied with topographic data and high-resolution visible images, but that was not available for Titan.
Instead, Dr. Hayes and colleagues used Earth-based radar images and degraded them to match Cassini’s Synthetic Aperture Radar (SAR) images of Titan.
This way, they could understand the limits of the Cassini dataset and know which results are robust for analysis using low, roughly 1-km resolution data.
“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,” said Julia Miller, a researcher in the Department of Astronomy at Cornell University and the Department of Earth, Planetary, and Space Sciences at the University of California, Los Angeles.
“River shapes say a lot. 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 NASA’s Dragonfly mission — which is scheduled to launch in 2027 and arrive at Titan in 2034 — finds locally and regionally, and will help to place its result into global context,” Dr. Hayes said.
The findings were published in the Planetary Science Journal.
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J.W. Miller et al. 2021. Fluvial Features on Titan and Earth: Lessons from Planform Images in Low-resolution SAR. Planet. Sci. J 2, 142; doi: 10.3847/PSJ/ac0245
