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Will the Mars Helicopter Induce Local Martian Atmospheric Breakdown?

Any rotorcraft on Mars will fly in a low pressure and dusty environment. It is well known that helicopters on Earth become highly-charged due, in part, to triboelectric effects when flying in sandy conditions. We consider the possibility that the Mars Helicopter Scout (MHS), called Ingenuity, flying at Mars as part of the Mars2020 Perseverance mission, will also become charged due to grain-rotor triboelectric interactions. Given the low Martian atmospheric pressure of ~ 5 Torr, the tribocharge on the blade could become intense enough to stimulate gas breakdown near the surface of the rotorcraft. We modeled the grain-blade interaction as a line of current that forms along the blade edge in the region where grain-blade contacts are the greatest. This current then spreads throughout the entire connected quasi-conductive regions of the rotorcraft. Charge builds up on the craft and the dissipative pathway to remove charge is back into the atmosphere. We find that for blade tribocharging currents that form in an ambient atmospheric dust load, system current balance and charge dissipation can be accomplished via the nominal atmospheric conductive currents. However, at takeoff and landing, the rotorcraft could be in a rotor-created particulate cloud, leading to local atmospheric electrical breakdown near the rotorcraft. We especially note that the atmospheric currents in the breakdown are not large enough to create any hazard to Ingenuity itself, but Ingenuity operations can be considered a unique experiment that provides a test of the electrical properties of the Martian near-surface atmosphere.