Dust Devils on Mars - burnt black trails and on the sides of sand dunes?

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How to ignore what you can see

Martian Dust Devils are amazingly electrical. Look at any image of the base of Mars Dust Devils and you will see blinding white flashing light like an arc welder gives off when it is discharging.





Martian Dust Devils also leave a black burnt trail after them, like the ground has been burnt or transformed. In the image below the swirling black marks are created by Dust Devils. But in this image you can also see very puzzling black streak marks going up or down the sides of the sand dunes.

What could cause the blackness on the sand dunes?

Intersecting swirling trails left by the earlier passage of dust devils across sand dunes, as they lifted lighter reddish-pink dust and exposed the darker material below. Also visible are darker slope streaks along dune edges, formed by a process which is still under investigation.
Mars Dust Devils trails and mysterious black streaks on the sand dunes

You can see how on the top left sand dune there is a black trail having gone over it that appears to not be stopped or covered over by the sand dune. So either an electrical discharge has created all the blackness or the dunes have somehow got the same blackness a fraction below there surfaces.



But what of the large black area at the bottom of the picture? Is it an older or more general electrical discharge event that has happened or is happening slowly now?

Mars electrical Dust Devils article

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dust devils on mars - animated sequence of an electrical dust devil

Electrical activities

Dust devils, even small ones (on Earth), can produce radio noise and electrical fields greater than 10,000 volts per meter.[11] A dust devil picks up small dirt and dust particles. As the particles whirl around, they bump and scrape into each other and become electrically charged. The whirling charged particles also create a magnetic field that fluctuates between 3 and 30 times each second.[12]

These electrical fields assist the vortices in lifting materials off the ground and into the atmosphere. Field experiments indicate that a dust devil can lift 1 gram of dust per second from each square meter (10 lb/s from each acre) of ground it passes over. A large dust devil measuring about 100 meters (330 ft) across at its base can lift about 15 metric tonnes (17 short tons) of dust into the air in 30 minutes. Giant dust storms that sweep across the world's deserts contribute 8% of the mineral dust in the atmosphere each year during the handful of storms that occur. In comparison, the significantly smaller dust devils that twist across the deserts during the summer lift about three times as much dust, thus having a greater combined impact on the dust content of the atmosphere. When this occurs, they are often called sand pillars.[13]

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mars has dust storms that start in a crater and grow to cover most of the planet

Martian dust devils

Dust devils also occur on Mars and were first photographed by the Viking orbiters in the 1970s. In 1997, the Mars Pathfinder lander detected a dust devil passing over it.[14][15] In the image shown here, photographed by the Mars Global Surveyor, the long dark streak is formed by a moving swirling column of Martian atmosphere. The dust devil itself (the black spot) is climbing the crater wall. The streaks on the right are sand dunes on the crater floor.

Martian dust devils can be up to fifty times as wide and ten times as high as terrestrial dust devils, and large ones may pose a threat to terrestrial technology sent to Mars.[16]

Mission members monitoring the Spirit rover on Mars reported on March 12, 2005, that a lucky encounter with a dust devil had cleaned the solar panels of that robot. Power levels dramatically increased and daily science work was anticipated to be expanded.[17] A similar phenomenon (solar panels mysteriously cleaned of accumulated dust) had previously been observed with the Opportunity rover, and dust devils had also been suspected as the cause.[18]

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the Mars Rovers are electrical in nature - either from their software/hardware, the fact they are moving over the surface, so must build up some static electricity and that they are made of different material to the rest of the surface and atmosphere.

what are the odds that these dust devils just randomly hit the Mars Rovers? or were they attracted to them because they were electrical?