Detection of triboelectric discharges during dust events on Mars

Lightning is among the most energetic manifestation of electrical activity in planetary atmospheres, with documented observations not only on Earth but also on Saturn and Jupiter. On Mars, the existence of electrical activity has long been suspected but never directly demonstrated. The dusty atmosphere of Mars undergoes aeolian processes, ranging from wind-blown dust and sand, metre-to-hundred-metre-sized dust devils to thousand-kilometre-scale dust storms, which, in Earth’s deserts, can become electrified through triboelectric charging. For this reason, electric fields have been predicted to build up on Mars, but with no measurement of Martian atmospheric electrical activity so far. Here we report in situ detections of triboelectric discharges, identified by their electrical and acoustic signatures captured by the SuperCam microphone aboard the Perseverance rover. Fifty-five events have been detected over two Martian years, usually associated with dust devils and dust storm convective fronts. These serendipitous observations demonstrate that Martian electric fields can reach the breakdown threshold of the near-surface atmosphere of Mars, predicted to be on the order of several tens of kV m−1. Such electrical activity could affect dust dynamics and potentially fuel a reactive electrochemical environment enhancing the oxidizing capacity of the atmosphere, with consequences for the preservation of organic molecules. This in situ evidence may have implications for surface chemistry, habitability and human exploration.