As perceived, sand storms on Mars are quite hefty. But how is that possible in such a thin atmosphere like Martian?
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6$\begingroup$ This was the biggest plot failure in The Martian -- such violent sand storms are not a thing on Mars. (And even if they were, trying to take off during a storm is surely the worst thing you can do!) $\endgroup$– TonyKMay 4, 2019 at 12:28
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9$\begingroup$ In case you are thinking about the book The Martian by Andy Weir, you should know that the author has publicly admitted the Dust Storm Scene to be a genuine scientific mistake. He did not account for the thin atmosphere, which means that a storm with Earth-Hurricane-like wind speeds will nonetheless only have the "destructive" power of a light breeze. Since this scene serves only to kick off the story and is not vital to the story itself, the author simply did not research it as diligently as he did most of the other details of the plot. $\endgroup$– Jörg W MittagMay 4, 2019 at 16:10
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3 Answers
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You might begin by reading this summary from NASA. Dust storms are indeed limited in intensity by the thin Martian atmosphere, but enhanced by the fine nature of the dust -- when the winds do blow they have a lot of surface area/mass ratio whereby they can pick up dust particles against the Martian gravity. The fine dust also gets into and sticks to equipment, making the equipment susceptible to damage from the storms even if the intensity is limited versus what there might be on Earth.
One key factor: Mars does not have copious liquid water on its surface. Sand and dust storms can be pretty impressive on Earth, too, but eventually the particles get captured by water either through precipitation or encountering a body of water. Mars does not have that checking mechanism, so once weather patterns enable a dust storm they may spread it globally.
According to the NASA reference above, this global accumulation ironically dooms the storm because the solar radiation that feeds the weather patterns becomes blocked. Hence global dust storms, impressive as they appear, are perforce temporary. This, too, shall pass.
answered May 4, 2019 at 12:06
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$\begingroup$ What effect does electric change bring to the mix? I remember charge accumulation on the rollin' robots being a major risk factor. I suppose the dust will absolutely prefer to fill as much space as possible ... NASA says "Mars’ dust storms aren’t totally innocuous, however. Individual dust particles on Mars are very small and slightly electrostatic, so they stick to the surfaces they contact like Styrofoam packing peanuts" .. ok, but what about the clouds and the lightning? $\endgroup$ May 4, 2019 at 20:56
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$\begingroup$ Whether Mars has copious liquid water or not is still yet to be determined, it's the lack of surface water that stops the fines being taken out of the atmosphere. $\endgroup$ May 4, 2019 at 21:10
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$\begingroup$ Mars also has lower gravity, making it easier (all else equal) for a particle to be picked up by the wind in the first place. $\endgroup$– VikkiMay 4, 2019 at 21:51
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Just to add a number to Oscar's answer, Martian dust is very fine, less than 30 micrometers, or less than about the size of a white blood cell. There's no water or other processes that would cause them to clump together. So it doesn't take much to swirl them around.
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2$\begingroup$ Mar's surface layer is a dust is made by micrometeor impact on the surface that creates a very fine particle size. Martian dust more like earth's "silt." In other words if you sprinkled Martian soil in water here on Earth, the particles are so fine that they would settle very very slowly. $\endgroup$– MaxWMay 4, 2019 at 17:45
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2$\begingroup$ Pretty much like powdered sugar then? (lsuagcenter.com/profiles/lbenedict/articles/page1491324916020 lists average grain sizes around 20 microns.) Yeah, that does not exactly need a tornado to be moved around. $\endgroup$ May 4, 2019 at 21:51
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Mars does not get sand storms, it gets dust storms. Whilst they are necessarily arbitrary classifications, the accepted size of particles of sand are between 0.06mm and 2mm. Mars dust particle sizes are estimated at below 0.05, which would be considered silt between 0.002 and 0.06mm and clay particles below 0.002.
(The below 0.05 mm size comes from "Measuring the Size and Charge of Dust Particles in the Martian Atmosphere" - Calle et al)
