It is shocking but not surprising. Lightning crackles on Mars, scientists reported on Wednesday.
What they observed, however, were not jagged, high-voltage bolts like those on Earth, arcing thousands of feet from cloud to ground.
Rather, the phenomenon was more like the shock you feel when you scuff your feet o the carpet on a cold winter morning and then touch a metal doorknob.
“This is like mini-lightning on Mars,” Baptiste Chide, a scientist at the Research Institute in Astrophysics and Planetary Science in Toulouse, France, said of the centimeter-scale electrical discharges.
Dr. Chide and his colleagues reported the findings in a paper published on Wednesday in the journal Nature.
The electrical sparks, although not as dramatically violent as on Earth, could play an important role in chemical reactions in the Martian atmosphere.
For future astronauts stepping onto the red planet, the minuscule shocks will not pose any danger of electrocution.
“Of course, it won’t kill you,” Dr. Chide said.
But over time, the electrical discharges — essentially short circuits jumping across gas molecules — could disrupt or damage electronic devices, including spacesuits. The new knowledge could help engineers design spacecraft and equipment headed for Mars.
Lightning has been seen on other planets in the solar system, in the atmospheres of Jupiter and Saturn. Because Mars is cold and dry, scientists have long thought that electric charge could build up in the air, especially during dust storms, when particles rub against each other and then discharge.
Searches for such electrical discharges have produced ambiguous and contradictory data.
The new findings, which are based on measurements taken by NASA’s Perseverance rover, may be more convincing.
“It’s pretty interesting, pretty significant and, I think, the most direct observational evidence we’ve got of electrical activity in Mars’s atmosphere that we yet have,” said Giles Harrison, a professor of atmospheric physics at the University of Reading in England who was not involved with the research. “I think it’s quite compelling.”
Interestingly, no one has yet seen a Martian mini-lightning bolt. Rather, the discovery was made by a microphone on Perseverance that heard the sound of the electrical discharge — the equivalent of mini-thunder.
The sound, not thunderous at all, is a pop of static.
The recording captured the low-frequency rumble of wind as a dust devil, or tiny tornado, passed over Perseverance. It also picked up the pings of dust grains hitting the rover. And there was also a louder sound.
Dr. Chide said the researchers were puzzled by the louder sound when they first analyzed the recording three years ago. “We concluded that it could be a bigger grain,” he said, referring to the dust.
Later, he attended a conference that discussed atmospheric electricity. He realized the sound could have been more like a zap that you might hear when you unplug an electrical device without first turning it off.
“And I thought, ‘Oh, if you have discharges on Mars, we would be able to hear them,’” Dr. Chide said.
A closer examination of the shape of the sound vibrations revealed that the zap looked like a shock wave. And there were two parts to the sound separated by a few thousandths of a second.
The first part was the radio emissions from the electric discharge, with the microphone acting as an antenna to pick them up. “We ran some simulations, and then we concluded this is exactly the waveform that we observe on our Mars data,” Dr. Chide said.
The second part was the pop of mini-thunder.
The brief separation between the two is like the delay between seeing a lightning strike on Earth and hearing the thunder, which, rumbling along at the slower speed of sound, arrives some seconds later.
The scientists calculated that the mini lightning strike occurred about six feet from Perseverance. They also found smaller, quieter zaps that occurred closer, within a few inches of the microphone.
This is not the first time that scientists have reported detecting electrical discharges on Mars.
In 2009, a team of researchers led by two professors at the University of Michigan, Christopher Ruf and Nilton Renno, reported microwave emissions from Mars that were not generated by the planet’s warmth.
That radiation corresponded with an intense dust storm, suggesting dry lightning as the cause.
Those measurements, however, were taken by a radio telescope on Earth. Observations by a European Mars orbiter failed to confirm the findings.
“We had no really definitive confirmation of this detection,” Dr. Chide said. “It was really controversial.”
Dr. Ruf and Dr. Renno, however, maintained that they had indeed detected electrical discharges on Mars.
They, too, said the new findings appeared to be robust. “It’s nice to see that our 2009 results are receiving some confirmation,” Dr. Ruf said in an email.
Kenneth Chang, a science reporter at The Times, covers NASA and the solar system, and research closer to Earth.
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