spaceSpace and Physics

Is Mars Already Forming A Ring System?


Jonathan O'Callaghan

Senior Staff Writer

Mars may one day develop a ring system like Saturn. janez volmajer/Shutterstock

In about 20 to 70 million years, it’s thought that the Martian moon Phobos will be torn apart as it moves closer to Mars, creating a ring of debris around the Red Planet similar to the planet Saturn.

But two researchers from the Physical Research Laboratory in India have found evidence that this process has already begun. They suggest the planet may already be developing a proto-ring system, with their findings published in the journal Icarus.


Jayesh Pabari and P. J. Bhalodi used data from NASA’s MAVEN spacecraft (Mars Atmosphere and Volatile EvolutioN Mission), which entered orbit around Mars in September 2014, to study the atmospheric composition of the Martian atmosphere.

They found that there was a cloud of dust surrounding the planet at an altitude of 150 to 1,000 kilometers (90 to 620 miles) above the surface, mostly made up of interplanetary debris. Mars and its moons are also thought to shed particles when they’re hit by asteroids, although these likely get carried away by solar wind.

But the dust cloud was also found to have a small amount of material, about 0.6 percent of its composition, that came from one of the two moons. They suggest this could be the start of a ring forming that would remain for the planet’s life. “The secondary ejecta from natural satellites of Mars can cause a dust ring or torus around Mars and remain present for its lifetime,” they wrote in their paper.

The orbit of Phobos is degrading by about 2 meters (6.5 feet) every century, with two possible outcomes. In about 20 million years or more, it will either crash into the Martian surface or be broken apart into a ring, depending on how solid it is.


That latter scenario now looks somewhat plausible, with bits of this moon – or possibly its companion, Deimos – already orbiting the planet. At the very least, it may leave behind a thin ring.

However, the idea that Mars is already forming a ring is contentious. MAVEN is not specifically designed to look for dust, and with no spacecraft having been sent to Mars to do so, we can only draw loose conclusions.

“To really say anything definitive about the dust, you really need to have a dedicated dust detector,” Laila Anderssen, from the University of Colorado Boulder, told New Scientist. “We still haven’t seen a good indication that there is significant material in the vicinity of the moons. So I think it’s a long shot […], but one should never say never.”


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