Saturn is the golden retriever of the solar system: it’s nice to look at and generally everyone’s favourite, including mine. While liking Saturn is admittedly a little basic, its 62 moons are anything but—it has a Death Star moon, a dumpling moon, and many other misfits. But its largest moon, Titan, might actually be the weirdest moon in the solar system. In addition to literal seas of methane, scientists are now reporting that Titan is full of electric sand.
A new study from Georgia Tech, published on March 27th in Nature Geoscience, sought to shed light on the massive and mysterious sand dunes engulfing Titan. Through laboratory experiments, the researchers found that under Titan-like atmospheric conditions, sand grains collide and become electrically charged, clumping together and remaining clumped for an incredibly long time. While wind-blown sand on Earth can also become electrically charged, the electrostatic forces are typically ephemeral and much weaker. The team compared the adhesive quality of the sand on Titan to packing peanuts and cats.
“Titan is a strange, electrostatically sticky world.”
“If you grabbed piles of grains and built a sand castle on Titan, it would perhaps stay together for weeks due to their electrostatic properties,” Josef Dufek, the Georgia Tech professor who co-led the study, said in a statement. “Any spacecraft that lands in regions of granular material on Titan is going to have a tough time staying clean. Think of putting a cat in a box of packing peanuts.”
Image: G.D. McDonald, J.S. Méndez Harper, NASA, JPL-Caltech, SSI
To reach this conclusion, the team created a modified pressure vessel and inserted naphthalene and biphenyl grains—hydrocarbon compounds similar in composition to what the sand is probably like on Titan. On Earth, naphthalene and biphenyl are considered toxic and are used moth balls and citrus fruit wrappings, respectively.
The team then added Titan-like “wind” by rotating the tube for 20 minutes in pure nitrogen environment, since that’s what the moon’s atmosphere is almost entirely composed of. Overwhelmingly, the sand stuck together, which doesn’t happen on Earth unless you add water to the mix. Speaking of Earth, our sand is mostly silica-based, and didn’t have the same sticky quality when the researchers used it to repeat their experiments.
“These non-silicate, granular materials can hold their electrostatic charges for days, weeks, or months at a time under low-gravity conditions,” study co-author George McDonald, said in a statement.
The new study offers the latest indication that although Titan looks astonishingly similar to Earth—it’s the only other world in the solar system with surface oceans, for one—many of the processes shaping its surface are truly alien.
“Titan’s extreme physical environment requires scientists to think differently about what we’ve learned of Earth’s granular dynamics,” Dufek said. “Landforms are influenced by forces that aren’t intuitive to us because those forces aren’t so important on Earth. Titan is a strange, electrostatically sticky world.”