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Dust devils on Mars, which are swirling columns of dust and air that frequently rake the planet's surface, may be electrically charged, according to a recent computer-modeling research. Varun Sheel headed a team of researchers that studied how Mars' dry atmosphere and frictional dust collisions charge grains inside a vortex. They discovered that these fields might become so powerful that transient lightning-like discharges could occur. This electrification raises concerns for surface missions because charged dust might stick to rover wheels, solar panels, and antennae, obscuring sunlight and disrupting with communications.
Formation and Features of Martian Dust Devils
The study found that dust devils occur when the Sun heats the surface of Mars, forcing heated air to ascend and spin into vortices. Colder air rushes inward along the ground, lengthening the rising column and propelling dust up into the sky. Because Mars has lower gravity and a thinner atmosphere than Earth, its dust devils can reach heights three times greater than Earth's storms. NASA's Viking mission discovered Martian dust devils, and rovers including as Curiosity and Perseverance have since captured footage of them rushing over the sandy plains. These whirlwinds clean solar panels, like Spirit did in 2005, but they also churn up fine dust, which may cover equipment.
Electrification and Risks to Rovers
Dust grains in Martian whirlwinds can accumulate charge through collisions (a triboelectric effect). According to Sheel's simulations, charge separation can result in powerful electric fields within a dust devil. These forces might possibly exceed Mars' atmospheric breakdown threshold (about 25 kV/m), causing lightning in the vortex. NASA's Perseverance rover captured what seems to be a minor triboelectric discharge when a dust devil swept overhead.
Even without lightning, static accumulation is hazardous. As planetary scientist Yoav Yair points out, "Electrified dust will adhere to conducting surfaces such as wheels, solar panels, and antennas," possibly decreasing sunlight reaching panels and jamming communications. Rovers may require novel design elements or processes to deal with the unpredictable Martian weather.
