Recent images from Mars suggest that new sand continues to form there, baffling scientists as to its source. New evidence indicates sand may generate from small amounts of water that boils and then levitates sand from the sediment, creating significant erosion across the Martian landscape.
The Life Cycle of Sand
Sand is created by weathering and erosion, which typically include the forces of wind, water or ice. Erosion breaks down pieces of rock or soil, and wind provides a strong mechanism for moving those pieces around. Yet, sand has a limited lifespan, and will eventually be turned to dust by the amount of forceful contact it experiences with wind along the way. This is commonly known to occur on Mars where a range of red dust hues covers the planet.
According to NASA, there are two types of wind experiences that can obliterate sand particles. The first is called saltation, where “[w]ind-blown sand is lifted above the surface of each planet before crashing onto the ground and bouncing in a sequence of repeated hops.”
The second is known as comminution: “Sand grains can also roll along the ground as they are blown by the wind, and they are also jostled by other sand grains that are similarly flying across the surface. All of these repeated impacts tend to wear down the sand grains, smoothing them into a more spherical shape and breaking off small fragments that supply the vast dust deposits of Mars.” NASA adds, “This process…ultimately destroys sand grains and limits the length of time that the particles exist.”
Because sand has a naturally limited life cycle—especially on Mars where wind storms are frequent and turbulent, often spreading dust and sand across the entire surface of the planet—sources of new sand are necessary.
A report from NASA explained, “The fact that we see active sand dunes on Mars today requires that sand particles must be resupplied to replace the grains that are lost over time.”
Moving water is the primary source of erosion that creates new sand. For example, our vast oceans constantly replenish our beaches with sand here on Earth. But without any knowledge of a similar, large water source on Mars, the source of new sand on Mars has continued to plague scientists.
As NASA scientists asked in a report: “Where are the modern day sources of sand on Mars?”
Siting of Possible New Martian Sand Source
NASA’s latest query followed even a most spectacular and related discovery. During a recent pass, NASA’s Mars Reconnaissance Orbiter (MRO) captured an image of what appears to be a sand-producing area. The large crater contains dark bedrock with evidence of the dark material eroding. Dark linear markings with that same hue—which slope downward—indicate sands eroded from that same bedrock, rather than being transported to that location by wind.
NASA reports, “Discovered in images from the Context Camera, this region exhibits dark material that is being eroded from dark layers in the bedrock of a semicircular depression near the boundary of the Southern highlands and the Northern lowlands. Downslope lineations support the notion that these dark sediments are derived locally, and did not accumulate here by coincidence because of the winds.”
To maintain the large sand dunes across Mars, deposits such as these must be common to keep the supply going. MRO will likely find many other similar sites as it explores the planet.
New Study Shows Possible Origin of New Sand
Still, scientists have been searching to understand the sources of new sand on Mars. Despite the absence of sizeable amounts of water on Mars and its thin atmosphere, scientists have recently discovered a new process that could explain large areas of erosion that create new sand and other features on the planet’s surface.
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