New Delhi:
In a first, scientists have discovered that the sands or particles that are spread all over the surface of Saturn’s moon Titan are ‘electrically charged’. These particles can stick together for months and can make for sturdy sandcastles. Saturn’s moon Titan’s non-silicate granules get kicked up and perform saltation, a process in which they begin hopping in a motion. This process takes place when the wind blows hard enough.
They turned frictionally charged on colliding just like what happens when you rub a balloon against your hair. They then bundle up together in such a way which is not observed for sand dune grains on Earth.
They actually become resistant to further motion.That charge is maintained by the sand particles for days or months at a time. They then attach to other hydrocarbon substances, like packing peanuts used in shipping boxes on Earth.
”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,” said Josef Dufek, from Georgia Institute of Technology in the US.
“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,” Dufek added.
The new findings may help explain an odd phenomenon. While the prevailing winds of Saturn’s moon Titan blow from east to west, the sandy dunes that are nearly 300 feet tall appears to form in the opposite direction.
“These electrostatic forces increase frictional thresholds,” said Josh Mendez Harper, a doctoral student at Georgia Tech.
”This makes the grains so sticky and cohesive that only heavy winds can move them. The prevailing winds aren’t strong enough to shape the dunes,” said Mendez Harper.
Researchers carried out a small experiment in a modified pressure vessel in their Georgia Tech lab in order to test particle flow under Titan-like conditions.
Grains of naphthalene and biphenyl – two toxic, carbon and hydrogen bearing compounds believed to exist on Titan’s surface were inserted into a small cylinder. The tube was then rotated for 20 minutes in a dry, pure nitrogen environment (Titan’s atmosphere is composed of 98 per cent nitrogen).
Then, the electric properties of each grain was measured as it tumbled out of the tube.
“All of the particles charged well, and about 2 to 5 per cent didn’t come out of the tumbler,” said Mendez Harper. “They clung to the inside and stuck together. When we did the same experiment with sand and volcanic ash using Earth-like conditions, all of it came out. Nothing stuck,” he said.
The sand on Earth too picks up electric charge when moved but they dissipate quickly as they are smaller, which is why when building a sand castle you need water to bind the particles together. This is not the case with Titan’s sand.
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“These non-silicate, granular materials can hold their electrostatic charges for days, weeks or months at a time under low-gravity conditions,” said George McDonald, a graduate student at Georgia Tech.
The findings were published in the journal Nature Geoscience.
