From orbit, this landscape on March looks like a lacy honeycomb or spider web. But the unusual polygon-shaped features aren’t created by bees or Martian spiders; they are actually formed from a continuous process of seasonal change created from water ice and carbon dioxide.
The Mars Reconnaissance Orbiter’s High Resolution Imaging Science Experiment (HiRISE) camera has seen many polygon shapes since 2006, when it entered orbit around Mars.
Above: Polygonal dunes on Mars, seen by the HiRISE camera on the Mars Reconnaissance Orbiter.
The HiRISE science team says that water and carbon dioxide in the solid form of dry ice play a major role in sculpting the surface of Mars at high latitudes.
Water ice frozen in the ground divides the ground into polygonal shapes. Then, dry ice sublimating just below the surface as the ground warms up in the spring creates even more erosion, creating channels around polygon boundaries.
Above: Spring fans and polygons on Mars, as seen by the Mars Reconnaissance Orbiter’s HiRISE camera.
The polygons form over many years as the ice near the surface contracts and expands seasonally.
But this polygon-covered region shows even more springtime activity, as evidenced by the fan-shaped blue features. Scientists say the layer of translucent dry ice covering the surface develops vents that allow gas to escape.
“The gas carries fine particles of material from the surface, further eroding the channels,” the team wrote on the HiRISE website.
“The particles fall to the surface in dark, fan-shaped deposits. Sometimes the dark particles sink into the dry ice, leaving shiny marks where the fans were originally deposited. Often the vent closes, then opens again, so we see two or more ventilators coming from the same location but pointing in different directions as the wind changes.”
Above: Detailed image of large-scale crater floor polygons caused by the desiccation process, with smaller polygons caused by thermal contraction within. The central polygon is 160 meters in diameter, the smaller ones are 10-15 meters wide, and the fissures are 5-10 meters in diameter.
Scientists study the polygon-patterned soil on Mars because these features help them understand the recent and past distribution of ice in the shallow subsoil, as well as clues about climatic conditions.
And Mars isn’t the only place with polygons. Polygons can be found in the Arctic and Antarctic regions of Earth, and the 2015 flyby by the New Horizons spacecraft also revealed polygons on Pluto.
Above: Polygons seen on Pluto.
At the center left of Pluto’s vast heart-shaped structure – informally named “Tombaugh Regio” – is a vast, craterless plain that appears to be no more than 100 million years old and possibly still shaped by geological processes.
This frozen region lies north of the icy mountains of Pluto and has been informally named Sputnik Planum (Sputnik Plain), after Earth’s first man-made satellite. The surface appears to be divided into polygon-shaped segments which are surrounded by narrow depressions.
Features that appear to be groups of mounds and fields of small pits are also visible. This image was acquired by the Long Range Reconnaissance Imager (LORRI) on July 14 from a distance of 48,000 miles (77,000 kilometers).
Features as small as half a mile (1 kilometer) in diameter are visible. The blocky appearance of some features is due to image compression.
This article was originally published by Universe today. Read it original article.
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