Researchers have discovered that Titan’s sand dunes, which can reach heights of 300 feet tall, face the opposite direction of the blowing winds — the image above shows the Cassini photos of the dunes on Titan (above) compared with terrestrial sand dunes (below). Scientists believe they’ve found an answer to the strange mystery. Still, the more intriguing issue with the sand dunes may be that they’re not made of sand at all.
Despite being just a moon circling around Saturn, Titan has quite a few things in common with the Earth. It’s atmosphere is mostly nitrogen (although it lacks oxygen), it’s the only other satellite in the solar system to have a liquid on the surface (liquid methane) and it sports its own sand dunes (roughly speaking). Titan also has harsh winds that continuously blow, yet Titan’s sand dunes seem to face the opposite direction of the winds.
Devon Burr and a team of researchers at the University of Tennessee, Knoxville, set out to understand that mystery using a wind tunnel originally made in the 1980s to simulate conditions on Venus. They found that the vast majority of the winds do little to affect the face of the planet. Instead, rare and powerful bursts of wind do most of the shaping.
As Dr. Burr explained, “this work highlights the fact that the winds that blow 95 percent of the time might have no effect on what we see.” According to a statement from the SETI Institute, the situation is similar to the damage done by infrequent, “perfect” storms at sea compared to the normal sea weather.
The statement explained a bit more on why these bursts occur.
“The winds on Titan occasionally reverse direction and dramatically increase in intensity due to the changing position of the Sun in its sky. Because the threshold wind speed is so high, only these stronger winds blowing from the west can move the sand and streamline the dunes.”
To understand why constant winds have little to do with Titan’s dunes, its important to remember that they’re not truly made of sand like on Earth’s surface. Dr. Burr explained that they’re not entirely sure what the material actually is, but they know the basic ingredients.
“The dunes are not made of silicates — sand — as on Earth or Mars, they’re hydrocarbons, and may possibly include particles of water ice that are coated with these organic materials.”
As Space.com explains, hydrocarbons — a combination of hydrogen and carbon — are the basic ingredients of a multitude of materials, what Titan’s dunes are made of exactly might stay a mystery until another vessel from Earth goes to Saturn.
Hopefully for sand dune enthusiasts, the next trip to Titan will be sooner rather than later.
[Image Credit: NASA]