Photos taken by the Mars Orbiter show a lot of “spider” patterns on the surface of Mars’ south pole when spring arrives.
Scientists recently built a laboratory chamber to simulate the Martian environment, which also has layers of gravel and dry ice. When the temperature in the chamber rises, as it does on Mars when spring arrives, the sand and soil below ejects up through the cracks in the dry ice, leaving a “spider” pattern on the surface of the dry ice – which researchers believe is the mysterious “spider” shape of Mars. This is how researchers believe Mars’ mysterious “spider”-shaped landscape is supposed to have formed.
A series of photos taken by NASA’s Mars Orbiting Rover (MRO) in 2018 showed the south polar regions of Mars covered by a layer of white dry ice in winter, but when spring came, these areas appeared in multiple dark, radial patterns. From an overhead view, it looks like a lot of spiders. Scientists were puzzled, adding to the many unsolved mysteries of Mars.
In the years that followed, scientists tried to come up with theories to explain the spider-like features, and one of them, that dry ice sublimation caused the erosion, received the most support from scientists.
What scientists already knew was that Mars has a high level of carbon dioxide in its atmosphere, so in the winter, it is cold enough for the carbon dioxide to turn into dry ice and cover the ground, forming a white cap of ice.
Scientists estimate that when spring arrives, sunlight penetrates through the translucent dry ice to warm up the gravel below. The dry ice is heated from the bottom and sublimation occurs – the physical process of changing directly from a solid state to a gas. This process causes the pressure on the dry ice to build up and eventually crack, with the underlying gravel blasting out of the cracks in the dry ice, thus leaving streaks of dark, radiating patterns on the dry ice layer.
Is this really the case? A recent experiment built by a research team at Trinity College Dublin, Ireland, is described in detail in a study published March 19 in the journal Scientific Reports, along with the results seen.
The researchers designed an airtight chamber lined with a layer of gravel of varying particle sizes. The researchers first used an electric drill to drill holes in the dry ice block to simulate the state of the dry ice layer on Mars. A manipulator suspended the dry ice on the gravel layer of the chamber, and the experimenters lowered the air pressure of the chamber to the level on Mars and placed the dry ice on the gravel surface.
They saw the Leidenfrost Effect, which means that when a substance comes into contact with a surface that is much hotter than its own sublimation temperature, a large amount of gas will be produced around the substance. Then, the researchers saw that the gravel under the dry ice in the role of pressure, from the hole in the dry ice ejected, in the dry ice left a strip of radial “mud trench”.
The researchers also noted that the gravel particles smaller areas, the jet led to the radial pattern more fine; gravel particles larger areas, the jet left a more sparse pattern.
Mary Bourke of the Department of Geography at Trinity College Dublin, who led the study, said this is the first study to experimentally validate the cause of the spider landscape on Mars, and that this innovative approach has implications for the study of planets with similar environments, such as Io (Europa) and Titan (Enceladus).
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