Mar 11, 2016
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The Sea of Sand. Earth Dunes vs. Martian Dunes

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Photo taken in Ouargla, Algeria. © All Rights Reserved by JDLS via Google Maps.

I put the “electric geology” tag because this could fit into the discussion of dune formation.

The dunes here seem to follow the so called star shape. Wikipedia says:

Radially symmetrical, star dunes are pyramidal sand mounds with slipfaces on three or more arms that radiate from the high center of the mound. They tend to accumulate in areas with multidirectional wind regimes. Star dunes grow upward rather than laterally. They dominate the Grand Erg Oriental of the Sahara. In other deserts, they occur around the margins of the sand seas, particularly near topographic barriers. In the southeast Badain Jaran Desert of China, the star dunes are up to 500 metres tall and may be the tallest dunes on Earth.

So, as always, let’s go to Mars and check the differences and similarities:

ESP_027864_2295
This image shows a variety of different dune types in southern Lyot Crater in the Northern lowlands at 48.9 degrees north. Transverse dunes to the west grade into longitudinal dunes downwind to the east and barchans to the south, possibly because of local winds channeled by topography in the impact basin. ESP_027864_2295. Image Credit: NASA/JPL/University of Arizona. See original here.
E03-2016_FHA-451anaglyph
Sand Dunes of Nili Patera in 3-D. Image Credit: NASA/JPL/Malin Space Science Systems. See original here.
ESP_027864_2295
Dunes on the Move. ESP_027864_2295. Image Credit: NASA/JPL/University of Arizona. This is an animation showing changes on one of the small barchans in the south of the dune field. The area pictured in the subimage is about 100 meters across. Winds from the west (left) have shifted the small ripples up the back of the dune towards the east. Sand has blown over the crest of the dune, cascaded down the steep slip face, and accumulated along the base of the slip face in the lee of the dune. In this way, the small dune advances slowly downwind.
Victoria_crater_from_HiRise-dunes
Sand dunes at. Victoria Crater at Meridiani Planum, Mars. TRA_000873_1780. Image Credit: NASA/JPL/University of Arizona. This is a crop of the original.
ESP_027236_1680
Bright Material along the Floor of a Trough in Noctis Labyrinthus. Image credit: NASA/JPL/University of Arizona. Original caption reads: Many of the troughs (or, rounded depressions) of Noctis Labyrinthus contain bright, sometimes layered, materials. Noctis Labyrinthus is located on the far western end of the large canyon system Valles Marineris. To the west lie the volcanoes of Tharsis. This HiRISE image shows an example of the bright material commonly found along the floors of some of the Noctis troughs. Spectral data from the CRISM instrument, also onboard the MRO spacecraft, indicate the bright material is hydrated (i.e., contains water).
PSP_001756_1995
Central Deposits in Pasteur Crater. Image credit: NASA/JPL/University of Arizona. Original caption reads: This observation shows a portion of the central sedimentary deposits in Pasteur Crater. The deposits in this image are eroding into knobs and ridges. The erosion is probably dominated by wind, as most of the ridges are parallel. This is common in wind-eroded features, with the ridges generally aligned with the prevailing wind.

The first 3 ones on top in my opinion resemble (a bit) more to earth dunes, that is, as if made by the wind. Let’s not forget however that Martian atmosphere’s density is just 0.6% of the Earth’s.  In the other three photos the dunes seem to stack forming voronoi-like cells.

At thunderbolts.info they have touched the subject of Martian dunes. I quote an excerpt from the article Ionic Tempest:

A Martian dust storm obscured an entire hemisphere several months ago. However, Opportunity reported only small pressure increases and minimal sand accumulation. This lends credence to the idea of “blowing” dust on Mars being caused by electrostatic discharges, rather than through the movement of its rarified atmosphere.

An ionic storm sometime in the recent past must have scoured immense amounts of material from the surface of Mars, gathering it into piles that are not oriented to prevailing wind patterns, but follow the line of charge transfer as it blew across the landscape. After the discharge passed, the heaps of ionized material instantly solidified in the same way as a volcanic pyroclastic flow will immediately harden into stone after it stops moving.

Electric weather? Here’s some electric tornado.

Also, see this:

Chalk Ramifications are made by effecting a discharge of an object on a resinous plate and then sprinkling the surface with a powder mixture. Images from Teslamania.com and G.W. Fransis' book Electrostatic Experiments. See these individually at para-oz.

Chalk Ramifications are made by effecting a discharge of an object on a resinous plate and then sprinkling the surface with a powder mixture. Images from Teslamania.com and G.W. Fransis’ book Electrostatic Experiments. See these individually at para-oz.

And this video:

panoramio

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