It is said that the entire history of the world can be read on a grain of sand, and NASA has taken this extremely seriously. Several Mars missions have been studying the planet's sand, it’s composition, and how it moves through the atmosphere.
Now the Mars Reconnaissance Orbiter (MRO) has spotted one of the locations on the Red Planet where sand grains are actually being produced. Using its Context Camera, the spacecraft captured dark sand being eroded from a bedrock of similar color.
The downslope on the sandy dunes shows that the sand is not accumulating there but that it’s slowly falling from the southern highlands into the northern lowlands. Without places like this, Mars wouldn’t have much sand.
Sand has a limited lifespan. Once picked up by winds, it rolls and jumps around the ground's surface. This process first smoothes out the grain of sand until eventually it’s broken down into dust. Then it can travel around the entire planet.
Mars’ atmosphere has a fraction of the density of our own, but its winds are effective at eroding rocks and forming dust. And Mars has dust storms that take over the entire planet. While these don’t have the same power as Earth’s dust storms, they can easily spread grains across the entire surface of the Red Planet.
To maintain the sand dunes we see on the ground and the dust storms we see in the atmosphere, these sand deposits have to be common, otherwise, there would be no resupply chain. MRO is likely to find many more sites like this one.