Scientists have detected what they believe to be lightning on Mars, thanks to the sensitive microphone aboard NASA's Perseverance rover. The discovery was made by eavesdropping on the planet's whirling winds, with the rover capturing the distinct crackling of electrical discharges.
A French-led research team reported on Wednesday that over two Martian years, 55 instances of what they term 'mini lightning' were documented. These phenomena predominantly occurred during dust storms and dust devils, almost exclusively on the windiest Martian days. The electrical arcs, mere inches in size, were detected within two metres of the microphone, which is part of a system used for examining Martian rocks.
Scientists have been searching for electrical activity and lightning on Mars for half a century, said the study's lead author Baptiste Chide of the Institute for Research in Astrophysics and Planetology in Toulouse. 'It opens a completely new field of investigation for Mars science,' Chide said, citing possible chemical effects from electrical discharges. 'It's like finding a missing piece of the puzzle.'
The evidence is strong but based on a single instrument meant to record the rover zapping rocks with lasers, not lightning, said Cardiff University's Daniel Mitchard, who was not involved in the study. In an article accompanying the study in the journal Nature, he noted that the electrical discharges were heard, not seen. 'It really is a chance discovery to hear something else going on nearby, and everything points to this being Martian lightning,' Mitchard said, but added that until new instruments verify the findings, debate may continue.
Electrical discharges generated by fast-moving dust devils lasted just a few seconds, while those from dust storms lingered up to 30 minutes. 'It's like a thunderstorm on Earth, but barely visible with a naked eye and with plenty of faint zaps,' Chide said. He noted that Mars' thin, carbon dioxide-rich atmosphere absorbs much of the sound, making some zaps barely perceptible. The small, frequent static-like discharges could prove problematic for sensitive equipment, but it is extremely unlikely to pose a risk to future astronauts.
