Scientists are already aware that unlike any other moon, Saturn’s largest moon, Titan, is filled with a dense atmosphere. There is little to no winds – in fact, winds appear to move twice in one Saturn’s year, which is about 30 years on Earth – yet sand dunes pile up for hundreds of yards high, over a mile wide, and hundreds of miles long. This is the mystery researchers have been struggling for years to solve because wind situations in Titan is limited to barely perceptible breezes.
This Saturn’s moon is also known to have rivers and lakes that are comprised of natural gas like methane and ethane – but researchers are more interested in finding out how sand dunes form on Titan – and they have been able to use a NASA improved wind tunnel to simulate a model of how this comes about.
A planetary scientist from the University of Tennessee, Devon Burr, “How this strange alien sand got there is still unknown, but even more baffling is the direction of the winds that create the dunes. Our models started with previous wind speed models but we had to keep tweaking them to match the wind tunnel data,” said Burr. “We discovered that movement of sand on Titan’s surface needed a wind speed that was higher than what previous models suggested.”
Scientists now believe sand dunes form when loose particles are driven by light breezes downwind to a hop – but then, the researchers also desire to understand the threshold wind speed that move the sand particles – and this led to a discovery that unlike sand dunes on Earth which are composed of silicate, the sand dunes on Saturn’s largest moon is made up of hydrocarbons that “may possibly include particles of water ice that are coated with these organic materials,” and it is now found that the minimum wind on Titan should be 50% faster than previously thought to move the sands.
“If the predominant winds are light and blow east to west, then they are not strong enough to move sand,” said Burr. “But a rare event may cause the winds to reverse momentarily and strengthen.” Anything higher than the normal wind threshold has informed the actual shapes of the sand dunes.