NASA rover records first evidence of lightning on Mars

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Paris (AFP) – NASA's Mars rover has recorded evidence of lightning on Mars for the first time, with its microphone picking up the sounds of tiny “explosions” caused by the dust storms that constantly sweep across the planet.

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Scientists have long debated whether electrical discharges could occur in the dusty and obscure Martian climate, but evidence has been hard to come by.

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It turns out that NASA's Perseverance rover, which has been roaming the Red Planet since 2021, accidentally recorded the sounds of lightning, according to a study published in the journal Nature this week.

This is a far cry from the kilometre-long thunderbolts we see on Earth.

Instead, they are “little clicks” similar to “what you might feel in dry weather when you touch a car door and there's a little static electricity,” study lead author Baptiste Chide of the French research center CNRS told AFP.

According to the planetary scientist, despite the low energy, these discharges occur “absolutely constantly and everywhere” on Mars.

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The process begins when tiny specks of dust rub against each other. They become charged with electrons and release this energy in electrical arcs several centimeters (inches) or even millimeters long, creating a sonic shock wave.

Here on Earth, dust storms and dust devils in desert areas also create electric fields. But they rarely develop into electrical discharges.

However, on Mars, “due to the very low pressure and composition of the atmosphere, the amount of charge that needs to be stored to generate a discharge is much less,” Tschide explained.

This phenomenon has been theorized since Mars was first explored and has been replicated in the laboratory.

Chide said it was “such an important question for Mars science” that an instrument on the European Space Agency's Schiaparelli lander was dedicated to searching for it.

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Unfortunately, the spacecraft crashed while attempting to land on Mars in 2016.

Since then, “it’s been kind of the lost territory for Mars exploration,” Chide said.

That was until, “by chance,” Perserverance’s SuperCam microphone picked up what appeared to be electrical discharges, he added.

Daniel Mitchard, a lightning expert at Cardiff University who was not involved in the study, commented in the journal Nature that the study provided “strong evidence for dust discharges.”

But since the discharges “were only heard and not seen,” he expected the debate among scientists on the matter to “continue for some time.”

– Electrified astronauts? –

The study may shed light on the mysterious Martian climate.

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“Dust determines the Martian climate,” similar to the water cycle on Earth, Tschide said. For example, by the end of the year the dust storm season will begin.

Electrical discharges can also trigger a process that breaks down organic molecules, the building blocks of life, on the surface of Mars.

It could also explain the surprisingly rapid disappearance of methane from the planet, a phenomenon that has baffled scientists.

This could also have implications for future missions to Mars.

According to Chide, scientists will now be able to develop their tools to better protect future robots sent to Mars.

And, of course, there are plans according to which people will finally set foot on the red surface of the planet.

“Isn’t there a long-term risk that the spacesuits of astronauts staying on the surface of Mars for a long time will be damaged by these discharges?” – asked Chide.

“We'll have to ask ourselves that question.”

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