 are examples of places where interior forces are at work today. The Appalachian Mountains represent much more ancient activity that produced similarly gigantic peaks long ago, which have since eroded.
Cassini has found that Titan also has rain and rivers that erode its landscape. According to Radebaugh, the process probably proceeds much more slowly on Titan than on Earth because, at 10 times Earth's distance from the sun, there is less energy to power erosive processes in the moon's atmosphere.
Titan's icy crust sits atop a deep ocean of liquid water that probably acts much like Earth's upper mantle -- the layer of hot, high-pressure rock below the crust that can slowly flow and deform over time. Once a period of mountain-building ends, these fluid layers (Earth's upper mantle and Titan's liquid ocean) allow the crust to relax, like a person settling into a waterbed. Also, at great depth, the water-ice bedrock of Titan is softer than rock on Earth. Because of these characteristics, scientists didn't expect mountains on Titan would tower quite as high as those on Earth, which can rise to more than 5 miles (nearly 9 kilometers) tall.
The fact that Titan has significant mountains at all suggests that some active tectonic forces could be affecting the surface, for example, related to Titan's rotation, tidal forces from Saturn or cooling of the crust. The next step for the researchers will be trying to figure out what could produce such tall peaks on an icy ocean world.
"There is lot of value in examining the topography of Titan in a broad, global sense, since it tells us about forces acting on the surface from below as well as above," said Radebaugh.
The Cassini-Huygens mission is a cooperative project of NASA, ESA (European Space Agency) and the Italian Space Agency. NASA's Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the mission for NASA's Science Mission Directorate, Washington. JPL designed, developed and assembled the Cassini orbiter. The radar instrument was built by JPL and the Italian Space Agency, working with team members from the US and several European countries.
More information about Cassini:
News Media ContactPreston Dyches
Jet Propulsion Laboratory, Pasadena, Calif.