(ORDO NEWS) — The spinning blades of drones flying over the surface of Mars can cause small electrical currents to flow through the Martian atmosphere, according to a new study by a team of NASA scientists.
These currents, if strong enough, can cause the air around the helicopter to glow. Such a process is widely known on Earth, where a corona-shaped glow can sometimes be seen above ships and aircraft, a phenomenon known as St. Elmo’s fire.
“This faint glow will be best seen in the evening hours when the sky background becomes darker,” said William Farrell of the Goddard Space Flight Center, USA, who is the lead author of the new study.
“NASA’s Ingenuity Experimental Helicopter is not flying during these hours, but future drones may very well fly at this time of day and observe this glow.”
This glow is caused by the triboelectric effect. The charge on the blades of a helicopter as a result of this effect is due to friction with air – just as a balloon acquires a charge as a result of friction with hair.
The team used laboratory experiments and computer simulations to study how electric charge builds up on the drone’s propeller blades.
As a result, it was found that when the drone’s propeller blades rotate, they effectively rub against Martian dust particles, especially when the helicopter is near the surface and raises clouds of dust around it. When dust particles collide, they transfer their charge to the blades, resulting in an electric field.
When the voltage rises to a critical value, an electrical breakdown of the surrounding air occurs and a gas discharge is observed as a bluish-violet glow in the atmosphere.
According to the authors, the discharge in the Martian atmosphere is lighter compared to the Earth’s atmosphere due to the lower density of atmospheric gases on the Red Planet.
As a result, free electrons have time to accelerate to speeds at which they knock out new electrons from CO2 molecules – and the current increases like an avalanche, which is the electrical breakdown of air.
Therefore, if on Earth for an electrical breakdown of 1 meter of air it is required to apply a voltage of 3,000,000 Volts, then on Mars, 30,000 Volts are enough, the authors explained.
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