The SuperCam microphone, the first to operate on Mars, captured especially strong transient signals as two dust devils passed over the rover. Researchers at the Institut de recherche en astrophysique et planetologie and the Laboratoire Atmospheres et observations spatiales showed that these signals match short electric arcs a few centimetres long, comparable to small static shocks experienced on Earth in dry conditions. Their work provides the first observational proof that triboelectric charging within Martian dust leads to discharges inside active dust structures.

On Mars, winds continuously raise fine dust into whirlwinds and storms, where grains collide and rub together, gaining and losing electrons. Once charge builds up beyond a threshold, it is released as sparks accompanied by shock waves that the microphone can record. Because the Martian atmosphere is thin and dominated by carbon dioxide, the electric field needed to trigger breakdown is lower than on Earth, so discharges can occur more readily for a given dust load.

The presence of such discharges has important consequences for atmospheric chemistry on Mars. The sparks can promote the formation of highly oxidising compounds capable of destroying organic molecules at the surface and altering many atmospheric species, shifting the photochemical balance of the atmosphere. The team notes that this mechanism could help account for the rapid and variable disappearance of methane reported in earlier measurements on Mars.

The electrical charging required to produce these discharges is also expected to influence dust lifting and transport, linking electrostatic effects directly to Martian climate and dust cycle dynamics. Changes in dust transport affect atmospheric heating, circulation patterns and the onset of local and global dust storms, processes that remain uncertain in current climate models. The new measurements provide a constraint for improving simulations and for planning future surface and orbital missions.

For spacecraft and prospective crews, electrically active dust presents an environmental hazard. Discharges and associated fields could disturb or damage sensitive electronics on current robotic platforms and must be considered in the design of systems for future human exploration. Understanding when and where such discharges occur will be important for assessing risk and developing mitigation strategies for rover operations and human habitats.

Since 2021, SuperCams microphone has collected more than 30 hours of Martian audio, including wind noise, sounds from NASAs Ingenuity helicopter and now the signals of dust driven electrical discharges. These observations show that acoustic measurements can probe not only mechanical noise but also electromagnetic processes through their sonic signatures. The results demonstrate the value of microphones as compact tools for studying atmospheric and surface phenomena in planetary exploration.

Research Report:Detection of triboelectric discharges during dust events on Mars

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