Using observations from NASA’s Cassini spacecraft in orbit around Saturn, researchers from NASA’s Goddard Space Flight Center have discovered that Titan — Saturn’s largest moon — has dunes of hydrocarbon sand which are slowly but steadily filling the impact craters left on the moon’s surface, giving it a deceptively younger appearance than its brothers and sisters in orbit.
“Most of the Saturnian satellites – Titan’s siblings – have thousands and thousands of craters on their surface. So far on Titan, of the 50 percent of the surface that we’ve seen in high resolution, we’ve only found about 60 craters,” said Catherine Neish, a Cassini radar team associate based at NASA’s Goddard Space Flight Center, Greenbelt, Md.
“It’s possible that there are many more craters on Titan, but they are not visible from space because they are so eroded. We typically estimate the age of a planet’s surface by counting the number of craters on it (more craters means an older surface). But if processes like stream erosion or drifting sand dunes are filling them in, it’s possible that the surface is much older that it appears.”
“This research is the first quantitative estimate of how much the weather on Titan has modified its surface,” adds Neish.
The discovery was made when Neish and her team started comparing craters on Titan to craters on Jupiter’s moon Ganymede, a giant moon with a water ice crust similar to Titan. The two moons should have been somewhat similar, but there were discrepancies.
“We found that craters on Titan were on average hundreds of yards (meters) shallower than similarly sized craters on Ganymede, suggesting that some process on Titan is filling its craters,” says Neish, who is lead author of the paper published in the journal Icarus.
There are several theories at hand that could explain the craters’ various depths, but the NASA team believe that windblown sand is the most likely option.