Almost All Of The Dust On Mars Comes From This One Place

A portion of the Medusae Fossae Formation on Mars that shows the effect of billions of years of erosion. NASA/JPL/University of Arizona

Mars is a dusty place. So dusty, in fact, that a global dust storm can easily cover it as has happened in the last month. Researchers looking into the origin of the dust have discovered that the vast majority originates from a single location: the Medusae Fossae formation.

The Medusae Fossae (the canyons of Medusa) is an enormous volcanic deposit that stretches for about 5,000 kilometers (3,100 miles) and is known for its complex terrain. It goes from a carved plateau full of ridges, grooves, and mesas to a smooth, gently undulating surface slowly being eroded away. Researchers know the chemical composition of the region, which was key for their study published in Nature Communications. The dust in the Martian atmosphere matches the geological formation.

“Dust everywhere on the planet is enriched in sulfur and chlorine and it has this very distinct sulfur-to-chlorine ratio,” lead author Dr Lujendra Ojha, from John Hopkins University, said in a statement.

In the last 3 billion years, the slow eroding action of winds has reduced the area of the Medusae Fossae by about 60 percent. And yet, it remains the largest volcanic deposit in the Solar System. The wind has taken away so much dust that the researchers estimate that if all the dust settled, it would form a global layer between 2 and 12 meters (6.6 and 39 feet) thick.

“Mars wouldn’t be nearly this dusty if it wasn’t for this one enormous deposit that is gradually eroding over time and polluting the planet, essentially,” added co-author Professor Kevin Lewis, also at Johns Hopkins. “It just explains, potentially, one big piece of how Mars got to its current state.”

Dust plays an important role in the changes of the Martian atmosphere. Dust absorbs more heat, leading to lower temperatures at ground level compared to the higher altitudes. This leads to stronger winds that can lift even more dust from the ground. This runaway mechanism can lead to the formation of global storms that happen about once a decade.

Dust is also problematic for our robotic explorers on the Red Planet. The fine powder lift by the wind can get into instruments and obscure solar panels, putting missions at risk.

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