Mars’ Moon Is Destined for Destruction

November 30, 2015 | Joanne Kennell

Artist's impression of a ring around the planet Mars
Photo credit: Tushar Mittal using Celestia 2001-2010, Celestia Development Team.

On the flip side, the planet might gain a Saturn-like ring.

The two moons of Mars, Phobos and Deimos, are named after the children of the god Ares, the Greek counterpart to Mars, the Roman god of war.  But Mars’ moon Phobos may be in serious trouble.  According to new research, long, thin “stretch marks” on the surface of the Martian moon are early signs that the moon is falling apart.  

"We think that Phobos has already started to fail, and the first sign of this failure is the production of these grooves," said Terry Hurford, a research assistant at NASA's Goddard Space Flight Center in Maryland, who led the study.

Phobos is closest to its planet than any other moon in our solar system, and it gets closer each year.  In fact, every 100 years, the moon moves 6.6 feet closer to Mars.  This approach will end in devastation for Phobos — the closer it gets, the effect of Mars’ gravity strengthens.  And in about 30 to 50 million years, the Red Planet’s gravity will break the moon apart.

SEE ALSO: Our Solar System is Missing One Giant Planet

Scientists already knew the fate of Phobos, however theory suggested that the moon would collide with Mars.  Until now.

Tushar Mittal, a graduate student at the University of California, Berkeley, and co-author Benjamin Black, a postdoctoral researcher at UC Berkeley, simulated the stress caused by the tidal pulls of Mars.  They looked at the moon’s characteristics such as composition and density, and compared it to other meteorites on Earth, to determine how much stress the moon could withstand.  

They found it to be made of porous, damaged rock on its exterior, and believe it is likely the same throughout its interior.  "The moon is probably neither a complete rubble pile, nor completely rigid," Mittal said. "The porosity of Phobos may have helped it survive."

After Phobos breaks apart, the pieces would continue to move inward towards Mars, however at a much slow pace.  The researchers suggested that it would take 1 to 100 million years for the remnants to fall to the Martian surface.

"Phobos is unique in that it is currently one of only a couple of inwardly evolving moons in our solar system that we know about," Mittal said. "However, since inwardly evolving moons inadvertently self-destruct, it is possible that more inwardly migrating moons may have existed in the past."  

Neptune’s moon Triton, is one of the other inward moving moons destined for destruction.  Saturn is also of interest.  Although most of Saturn’s rings are made of space-dust, some of it could be debris of early moons that broke apart as they travelled to close to the massive gas giant.

Although Phobos is ultimately doomed, its trek towards Mars can help aid scientists understand the evolution of our solar system and the fate of moons that have already been destroyed or are en route for annihilation.

With humans on track for travel and eventual colonization of the Red Planet, what sort of problems could this ring present?  According to scientists, if the ring forms and is confined to a single, stable ring, it should not create any problems for exploration and travel to Mars.  However, “Any deorbiting ring particles could be a potential hazard for a Mars base built near the equator," said Mittal.

Well that’s easy enough, just don’t build within Mars’ equatorial region for the next 100 million years.

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