Riverbeds on Titan Have Surprisingly Little Erosion
The surface of Saturn's largest moon, Titan, has long been obscured to Earth-bound telescopes by its thick, gas-filled atmosphere. But in 2004, the Cassini-Huygens probe that orbits Saturn returned radar images of Titan's icy terrain carved out over millions of years by rivers of liquid methane. And now, a new analysis of the landscape reveals that the riverbeds have a surprisingly low amount of erosion.
Similar to the process of river beds on Earth being carved out by eons of erosion, the wearing away of Titan's methane river networks should have created more erosion.
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"It's a surface that should have eroded much more than what we're seeing, if the river networks have been active for a long time," said Taylor Perron, Assistant Professor of Geology at MIT. "It raises some very interesting questions about what has been happening on Titan in the last billion years."
Titan is around four billion years old, about the same age as the rest of the solar system, but it doesn't look its age. Judging by the number of craters on the moon, one might estimate that its surface is much younger, between 100 million and one billion years old.
Titan is fresh-faced with few craters -- which is a lot like Earth. Craters are rare on our planet because dynamic events like earthquakes, volcanoes, glaciers and oceans are eroding them away, or covering them up, reports Wired UK.
"We don't have many impact craters on Earth," Perron said. "People flock to them because they're so few, and one explanation is that Earth's continents are always eroding or being covered with sediment. That may be the case on Titan, too."
The researchers suggest that icy lava eruptions or tectonic upheaval may be at work on Titan, leaving riverbeds filled in before they can erode as one would expect.
Perron and MIT graduate student Benjamin Black set out to determine the extent to which river networks may have renewed Titan's surface. With the help of images taken from the Saturn probe, they mapped 52 prominent river networks from four regions on Titan and found the moon's rivers most resembled the early stages of a typical terrestrial river's evolution. In some regions, these methane rivers have caused very little erosion into the icy face of Titan.
Oded Aharonson, a professor of planetary science at the California Institute of Technology, says analyzing geologic processes on Titan may help scientists understand how rivers form. "Besides Earth, Titan is the only world where we see active river networks forming as a result of an active hydrologic cycle," Aharonson said. "The finding suggests the process of river erosion on Titan is currently responding to resurfacing or resetting of the surface."
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