A NASA rover has recorded evidence of lightning on Mars for the first time, with its microphone picking up the sounds of tiny “zaps” whipped up by the dust storms that constantly sweep across the planet.
Scientists have long debated whether electrical discharges could occur in the dusty, little-known Martian climate, but evidence has been difficult to find.
It turns out that NASA’s Perseverance rover, which has been roaming the red planet since 2021, was inadvertently recording the sound of lightning, according to a study published in Nature this week.
These are far from the kilometer-long thunderous lightning bolts we see on Earth.
Instead, they are “small bumps” similar to “what you can feel in dry weather when you touch your car door and there is a little bit of static electricity,” said lead author Baptiste Chide of France’s CNRS research center. AFP.
While low in energy, these discharges occur “absolutely all the time and everywhere” on Mars, the planetary scientist said.
The process begins when small grains of powder rub together. They are charged with electrons and release this energy in electric arcs a few centimeters or even millimeters long, emitting an audible shock wave.
Here on Earth, dust storms and dust devils in desert areas also create electric fields, but they rarely become electrical discharges.
However, on Mars, “due to the very low pressure and composition of the atmosphere, the amount of charge that needs to accumulate to generate a discharge is much lower,” Chide explained.
This phenomenon has been theorized since Mars began to be explored and has been reproduced in the laboratory.
Chide said it had been “such an important question for Martian science” that an instrument on the European Space Agency’s Schiaparelli lander was dedicated to searching for it. Unfortunately, the spacecraft crashed while attempting to land on Mars in 2016.
Since then, “it was kind of a forgotten area for Martian exploration,” Chide said.
That is, until “by chance” the microphone on Perserverance’s SuperCam recorded signals of 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 Nature that the research provided “compelling evidence of dust-induced discharges.”
But since the discharges were “only heard and not seen,” he expected that the debate among scientists on the subject would “continue for some time.”
Electrified astronauts?
The research could shed some light on the mysterious Martian climate.
“Dust drives the Martian climate,” similar to the water cycle on Earth, Chide said. For example, by the end of the year a dust storm season will have begun.
Electrical discharges could also initiate a process that destroys organic molecules, which are the building blocks of life, on the Martian surface.
It could also explain the surprisingly rapid disappearance of methane on the planet, a phenomenon that has baffled scientists. It may also have implications for future missions to Mars.
Scientists will now be able to design their instruments to better protect future robots sent to Mars, Chide said. There are also plans for humans to finally set foot on the planet’s red surface.
“In the long term, isn’t there a risk that these discharges will damage the suits of astronauts who remain on the Martian surface for a long time?” —Chide asked.
“We will have to ask ourselves this question.”
