With Mars’ largest moon Phobos expected to eventually breakup, scientists have wondered whether it would crash into the Red Planet or do something else.
Now, a team from UC Berkeley is predicting that Phobos would be shredded into pieces before it reaches Mars, a process that would result in a ring of debris encircling the planet as is the case with Saturn, Jupiter, Uranus and Neptune.
“If the moon broke apart at 1.2 Mars radii, about 680 kilometers above the surface, it would form a really narrow ring comparable in density to that of one of Saturn’s most massive rings,” Tushar Mittal, who co-authored a paper in Nature Geoscience on the moon with Benjamin Black, said. “Over time it would spread out and get wider, reaching the top of the Martian atmosphere in a few million years, when it would start losing material because stuff would keep raining down on Mars.”
Mittal said it’s not clear whether the dust and debris rings would be visible from Earth, since dust does not reflect much sunlight, whereas ice in the rings of the outer planets makes them easily visible. But Mars’ ring may reflect enough light to make Mars slightly brighter as seen from Earth and the rings might look like shadows when viewed through a telescope from Earth.
“Standing on the surface of Mars a few tens of millions of years from now, it would be pretty spectacular to watch,” Black said.
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The process – which won’t happen for some 20 to 40 million years – is driven by tidal forces that will eventually pull Phobos apart as it approaches Mars.
Just as Earth’s moon pulls on our planet in different directions, rising tides in the oceans, for example, so too Mars tugs differently on different parts of Phobos. As Phobos gets closer to the planet, the tugs are enough to actually pull the moon apart, the scientists say. This is because Phobos is highly fractured, with lots of pores and rubble.
Jesús Sánchez García
Pablo Dorador Ontiveros
Dulce María Saéz Martinez