Saturn's moon Titan 'ideal for sand castles thanks to static electricity'
Saturn's moon Titan has land surfaces covered with "electric sand", scientists believe.
Static electricity is thought to cause the particles to cling together in much the same way as hair sticks to a rubbed balloon.
The effect is thought to explain the moon's striking 300ft tall sand dunes which form against the wind, unlike those on Earth.
It also makes Titan, one of the planet Saturn's numerous moons, the perfect place for building sand castles.
Professor Josef Dufek, from Georgia Institute of Technology in the US, who co-led a new study of the phenomenon, said: "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.
"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'."
The electrically charged sand grains are likely to be so sticky that only heavy winds would be able to move them, said the scientists whose findings are reported in the journal Nature Geoscience.
This could help explain how prevailing winds blow from east to west on Titan yet the sand dunes are able to form in the opposite direction.
The scientists mimicked Titan's electric sand effect in a laboratory experiment using grains of naphthalene and biphenyl, two hydrocarbon compounds believed to exist on the moon's surface.
While Earth sand does become electrically charged when moved, the charges are small and dissipate quickly. That is one reason why water is needed to pack sand together when building a sand castle.
On Titan, it would be possible to fashion fabulous long-lasting sand castles without a drop of water.
"These non-silicate, granular materials can hold their electrostatic charges for days, weeks or months at a time under low-gravity conditions," said graduate student co-author George McDonald, also from Georgia Institute of Technology.
Titan has a thick atmosphere and geological features that resemble those of Earth, including dunes, mountains, rivers and seas.
But instead of surface water, the moon has liquid methane and ethane that is replenished by rain from hydrocarbon-filled clouds.
"Titan's extreme physical environment requires scientists to think differently about what we've learned of Earth's granular dynamics," said Prof Dufek.
"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."
