"Mini-lightning strikes created by whirling dust devils on Mars have been detected accidentally by the microphone on board the Perseverance rover. The chance discovery is direct evidence of a form of lightning on Mars, researchers say in a report published in Nature. They describe how the rover's microphone picked up signs of electrical arcs just a few centimeters long, which were accompanied by audible shockwaves."
"For example, when researchers put volcanic sand into a flask and pumped it down to Martian atmospheric pressures, swirling the sand in the flask created a glow that could be seen in the dark, says Ralph Lorenz, a planetary scientist with the Johns Hopkins University Applied Physics Laboratory. The glow came from electrical charges caused by the friction between the bits of sand."
The Perseverance rover's microphone recorded electrical arcs and audible shockwaves produced by whirling dust devils, indicating mini-lightning discharges on Mars a few centimeters long. The audio evidence provides direct detection of electrostatic discharges on the Martian surface. Lightning and electrical activity have been observed on other giant planets and ice giants, but detection on Mars was elusive until now. Laboratory experiments at Martian pressures showed volcanic sand swirling produces visible glow from triboelectric charging; friction between grains builds electric charge that can produce sudden discharges analogous to spark plugs or volcanic-ash lightning on Earth. Dust-driven electrostatic activity can therefore generate localized lightning on Mars.
Read at www.npr.org
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