Researchers may have solved a long-standing mystery surrounding the gigantic sand dunes of Titan, Saturn’s largest moon. The dunes could be composed of electrified sand particles.
Discovered by Cassini, Titan is Saturn’s main satellite. It measures 5000 kilometers. By its dimensions, it is thus located between Mercury and Mars. During a flyby of the moon on July 25, about 980 kilometers away, the probe penetrated the dense atmosphere that coats Titan to reveal fine details on its surface thanks to its radars. The images then depicted a desolate and icy alien landscape made up of hundreds of gigantic sand dunes in rugged mountainous areas.
Titan’s dunes sometimes tower up to a hundred meters high, but while the prevailing winds blow across Titan from east to west, the dunes themselves have formed as if blown in the opposite direction. Researchers now think they know why: the dunes could be made up of electrified sand particles. The shape and orientation of the dunes observed on Titan would therefore not be due to the activity of the wind on the surface, but to the chemical composition of the sand itself.
Unlike Earth’s sand which is mainly composed of silica (silicon dioxide), sand particles on Titan are today thought to be a kind of ice pellets, solid water coated with hydrocarbons which fall from the atmosphere. Remember, Titan’s lakes and rivers are filled with liquid methane, especially in the far north of the satellite.
To see how these hydrocarbon-rich particles might behave under Titan’s conditions, researchers at Georgia Tech in Atlanta, who are publishing a study in the journal Nature Geoscience, experimented with the reactions of naphthalene and biphenyl grains (two compounds believed to exist on the moon). They then placed them in a pressurized cylinder designed to simulate Titan’s atmosphere (98% nitrogen) by notably imitating the friction generated by the winds. After twenty minutes, they then discovered electrically charged grains.
Titan is therefore a strange, toxic and electrostatic world, a world where the prevailing winds are not strong enough to shape the dunes. Here on Earth naphthalene is an active ingredient in mothballs known to cause cancer. On Titan, this compound would probably still be just as bad for us, but it would achieve some feats at least in theory. » Imagine building a beautiful sandcastle at the foot of the dunes. Then you wouldn’t need any liquid to bind the grains together and your castle would stay that way, intact for weeks due to its electrostatic properties. jokes Josef Dufek, co-author of the study, in a press release.
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