Search for in situ signatures of electric activity on Mars

Electrical discharges such as lightning are among the most energetic and remarkable phenomena in planetary atmospheres. Both laboratory experiments and modeling studies have predicted that triboelectric charging of wind-blown particles in dust events on Mars should lead to significant electrification. However, there have been no direct measurements of a Martian electric field or observations of discharges. Here, using acoustic recordings from the SuperCam microphone onboard the Perseverance rover, we report evidence for an atmospheric discharge in a dust devil, based on the electromagnetic and acoustic signatures observed in the microphone signal. This is the first direct detection of a triboelectric discharge in the Mars atmosphere. It shows that the electric field in a dust devil can reach 25 kV/m, which is the expected breakdown threshold of the Mars atmosphere. Electrical discharges on Mars may have implications for dust dynamics, the chemistry of oxidants and methane in the atmosphere, and ultimately robotic and human exploration.