Astronomy Picture of the Day
April 25, 2013

Winds in Action!
Winds in Action!

Credits: NASA/JPL/University of Arizona - Credits for the additional process. and color.: Dr Paolo C. Fienga/Lunar Explorer Italia/IPF

This image, taken by the NASA - Mars Reconnaissance Orbiter in the late March of the AD 2011, as well as many other similar ones (taken from both the orbit as well as the Surface of the Red Planet) have helped Planetary Scientists to realize that Dust Devils on Mars are a far more common phenomenon that it had ever been thought in the past. The Dust Devils (which normally occur also on our Home Planet Earth) look like "Mini Tornadoes" and they are made up of swirling vortices of air that pick up very fine pieces of Dust (---> such as the smallest particles of Soil, much finer than a grain of Sand); furthermore, the Dust Devils also play an important role in the Martian Climate and Geology.

As far as the influence of the Dust Devils on the Martian Climate is concerned, we must consider that a Dusty Surface tends to be brighter - and therefore it reflects most of the incoming Sunlight - than a dust-free one; given that, we can say that the Dust Devils, through their relentless "dust-sweeping-and-lifting action", collectively concur to darken the Surface of Mars, and so to make it fit to absorb more Sunlight. This process of heat-absorbtion, in the end, causes a diffuse warming up the Surface as well as of the Air that is close to it. In addition to that, we also have to consider that Dust Devils can also "kick" (---> lift/push up) huge amounts of Dust into the Air where the Dust itself remains suspended for a while, before setting down again. As you can easily imagine, in that time, the Suspended Dust Particles can absorb the Sunlight passing through the Martian Atmosphere and thus they can warm it up in a more direct, and even much faster way.

As far as the influence of the Dust Devils on the Martian Geology (and Surface Morphology) is concerned, we have to take into account that their high Wind-speeds can be strong enough to shift and move around Sand that otherwise would have remained in one specific location forever. In fact, by moving Surface Soil Grains around, the Dust Devils can also serve to mix, on the Surface of Mars, different Minerals which were picked-up from various (and, perhaps, sometime even quite distant) locations. Last, but not least, you also have to think that each year, myriads of Dust Devils crisscross the Martian Surface scouring up loose Dust and, by removing it, they, in fact, modify (sometimes in a very deep way!) the Surface itself, either by creating new or by erasing (---> sweeping away) old Surface Features.

Mars Local Time: 14:50 (Early Afternoon)
Coord. (centered): 14,637° South Lat. and 175,540° East Long.
Spacecraft altitude: 266,0 Km (such as about 165,186 miles)
Original image scale range: 26,6 cm/pixel (with 1 x 1 binning) so objects ~ 80 cm across are resolved
Map projected scale: 25 cm/pixel
Emission Angle: 8,6°
Phase Angle: 49,7°
Solar Incidence Angle41° (meaning that the Sun was about 49° above the Local Horizon at the time the picture was taken)
Solar Longitude: 265,3° (Northern Fall - Southern Spring)
Credits: NASA/JPL/University of Arizona
Additional process. and coloring: Lunar Explorer Italia

This picture (which has been cropped from a NASA - Original Mars Reconnaissance Orbiter NON-Map Projected JP2 CTX b/w frame identified by the serial n. ESP_021925_1650) has also been additionally processed and then colorized in Absolute Natural Colors (such as the colors that a human eye would actually perceive if someone were onboard the NASA - Mars Reconnaissance Orbiter and then looked down, towards the Surface of Mars - Region of Gusev Crater), by using an original technique created - and, in time, dramatically improved - by the Lunar Explorer Italia Team.

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