But new calculations from astronomers at the University of California, Berkeley, find that Phobos, which is comprised of weakly connected material, will instead be torn apart by Mars’ gravitational pull and redistributed as a ring around the planet, like the famous rings of Saturn or Neptune. That means the grooves are like “stretch marks” caused by Mars’ tidal forces – an indication that Phobos is slowly deforming.
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Mars’s moon Phobos is spiralling toward the Red Planet, and within 40 million years, it’s expected to break apart to form a ring, or crash into Mars.
Earlier this month, NASA reported that Mars’s moon Phobos is gradually falling apart.
When Phobos does start to break apart, the authors calculate the process may only take five orbits.
The oval-shaped moon, which is 27 kilometres long and 18 kilometres wide along its longest and narrowest dimensions, also has a crater on it that is 10 kilometres in diameter, suggesting it was heavily damaged when it was hit by the object that produced the crater. They are all gas giants. “But because that material will be spread over a smaller ring area, we predict that the initial density of a ring formed from the breakup of Phobos could rival or exceed the density of Saturn’s rings”.
“Any large fragment of Phobos that is strong enough to escape tidal breakup will eventually collide with Mars in an oblique, low-velocity impact”, the researchers write.
Over time Phobos is creeping inwards towards Mars at a couple of centimetres per year.
“Our analysis of the evolution of Phobos underscores the potential orbital and topographic consequences of the growth and self-destruction of other inwardly migrating moons – including those that met their demise early in our Solar System’s history”.
Every century, gravity pushes Phobos 2 meters (6.6 feet) closer to Mars. Phobos is the larger and orbits so close to Mars – about 3,700 miles above the surface or only 1.5 percent of the distance between Earth and its moon. “With samples from this moon we can get information about the origin of the Solar System”.
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The researchers added that a number of missions to Phobos have been proposed, and those spacecraft might be able to make measurements that will help test their prediction.
