Most Mars dust comes from one place

A portion of the Medusae Fossae Formation on Mars showing the effect of billions of years of erosion. The image comes from a camera onboard the Mars Reconnaissance Orbiter. Image via NASA/JPL/U. Arizona.

Mars is currently experiencing a planet-wide dust storm. Seasonal dust storms happen every Martian year, but global dust storms like the current one happen about every 10 or so years.

Like in the movie “The Martian,” where a dust storm strands an astronaut played by actor Matt Damon, the current dust storm on Mars is causing severe problems for real missions – for example, the Opportunity rover, which has had to suspend science operations. The fine, powdery stuff can get into expensive instruments and obscure solar panels needed to power equipment.

So where does all this dust come from? A new study says that the dust that coats much of the Martian surface originates largely from a single 1,000-kilometer-long (600-mile-long) geological formation near the planet’s equator. The study, published July 20, 2018, in the peer-reviewed journal Nature Communications found a chemical match between dust in the Martian atmosphere and the surface feature, called the Medusae Fossae Formation.

Side-by-side movies shows how dust has enveloped the red planet, courtesy of the Mars Color Imager (MARCI) camera onboard NASA’s Mars Reconnaissance Orbiter (MRO). The view from May shows Valles Marineris chasms (left), Meridiani center, an autumn dust storm in Acidalia (top) and the early spring south polar cap (bottom). The view from July shows the same regions, but most of the surface was obscured by the planet-encircling dust cloud and haze.

Study co-author Kevin Lewis is an assistant professor of Earth and planetary science at the Johns Hopkins University. Lewis said in a statement:

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.

The team studied data captured by the Mars Odyssey spacecraft, which has orbited the planet since 2001. They also looked at the Mars dust’s chemical composition. Landers and rovers far apart on the planet have all reported surprisingly similar data about the dust. Lujendra Ojha, the study lead author, said:

Dust everywhere on the planet is enriched in sulfur and chlorine and it has this very distinct sulfur-to-chlorine ratio.

The researchers were able to pinpoint the Medusae Fossae Formation region as having an abundance of sulfur and chlorine, as well as a match to the ratio of sulfur to chlorine in Mars dust.

Here on Earth, dust is separated from soft rock formations by forces of nature including wind, water, glaciers, volcanoes and meteor impacts. But on Mars, for more than 4 billion years, say the researchers, those forces have made only small contribution to the planet’s global dust reservoir. Ojha also said:

How does Mars make so much dust, because none of these processes are active on Mars?

Earlier findings suggest that the Medusae Fossae Formation had a volcanic origin. Once the size of half the continental United States, the wind has eroded it, leaving behind an area that’s now more like about 20 percent. Yet it is the largest known volcanic deposit in our solar system.

By calculating how much of the Medusae Fossae Formation has been lost over the past 3 billion years, the scientists could approximate the current quantity of dust on Mars, enough to form a 7 to 40 foot (2 to 12 meter) thick global layer.

Bottom line: A new study says that the dust that coats much of the surface of Mars originates largely from a single 1,000-kilometer-long (600-mile-long) geological formation near the planet’s equator called the Medusae Fossae Formation.

Read more from Johns Hopkins University

July 27, 2018

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