While Martian dust dominates the lower atmosphere, dust from other sources, like the planet's moons Phobos and Deimos, is sprinkled in the upper part. A new model based on NASA's Mars Atmosphere and Volatile Evolution Mission (MAVEN) spacecraft suggests that most dust is from interplanetary sources.
"It has been found that flux rate at Mars is dominated (~2 orders of magnitude higher) by interplanetary particles in comparison with the satellite originated dust," say Jayesh Pabari and P.J. Bhalodi in an article published in the journal Icarus.
"It is inferred that the dust at high altitudes of Mars could be interplanetary in nature," they continue, "and our expectation is in agreement with the MAVEN observation."
Zurek said scientists are monitoring the infall of dust into Mars' atmosphere, and saw a spike when Comet Siding Spring zoomed close to the planet in October 2014, shortly after MAVEN arrived. The spacecraft detected a particular kind of dust - magnesium - that was ionized as it fell into the atmosphere, generating auroras.
At upper altitudes, however, dust does not have much effect on the climate, Zurek said. Occasionally particles will seed clouds, but that's about it. Zurek added that the effects could have been different in the ancient past, when there were more asteroids jumbled around the solar system and thus more dust was falling into Mars.
Some recent media reports discussing the paper suggested that a dust ring may be forming around Mars, but Zurek said there's no evidence of a substantial ring happening - or even a tenuous one, like what is around Jupiter.
"We haven't been able to find it yet, but we keep looking," he said with a chuckle.
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