Electrified whirlwinds on Mars can produce lightning-like discharges, which could pose a threat to the rovers trundling around on the Red Planet鈥檚 surface.
Severe weather on Mars can sometimes create dust devils, whirlwinds of Martian soil that spin for a few minutes before vanishing. Dust devils form on Earth too, and they can become electrified when the larger dust particles they carry 鈥� which tend to be positively charged 鈥� fall to the ground, while smaller and negatively charged particles are lofted upwards. If this electric field becomes large enough, the devil can suddenly discharge its energy, in a lightning-like jolt.
Now, at the Institute of Research in Astrophysics and Planetology in Toulouse, France, and his colleagues have observed Martian dust devils producing electrified shocks too. The evidence comes from audio that they recorded using NASA鈥檚 Perseverance rover鈥檚 on-board microphone. Chide and his team at the Lunar and Planetary Science Conference in The Woodlands, Texas, on 13 March.
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A dust devil passed directly over the Perseverance rover in 2021, and Chide and his team noticed that its microphone had detected unusual sounds. The audio recording contained a sharp, intense peak as the centre of the vortex passed over the rover, followed by a second, slightly smaller peak a few milliseconds later.
Chide and his team theorised that the first peak came from electromagnetic radiation released when the dust devil鈥檚 electric field collapsed, while the second peak represented a sound wave produced by the electric field collapse, similar to a clap of thunder following lightning.
They then reproduced this pattern in the lab using a . 鈥淎ll the features that we observed in the Mars data were able to be reproduced in the lab, which supports that the signal that we observed on Mars comes from an electrostatic discharge,鈥� Chide said during his conference presentation. The researchers also realised that a previous dust devil that Perseverance encountered had produced a similar signal, meaning they had evidence of multiple dust devil shocks.
According to the researchers, the energy from such electrical discharges could present a risk to Mars rovers. They speculate that the electrical energy could even pose a problem for future plans to put humans on the Red Planet.
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