EUROPE: Mars’ largest moon Phobos is slowly falling towards the planet and is likely to be shredded into pieces that will be strewn about the red planet in a ring like those encircling Saturn and Jupiter, scientists say.
Though inevitable, the demise of Phobos is not happening anytime soon. It will probably happen in 20-40 million years, leaving a ring that will persist for anywhere from one million to 100 million years, say scientists at the University of California, Berkeley.
UC Berkeley postdoctoral fellow Benjamin Black and graduate student Tushar Mittal estimate the cohesiveness of Phobos and conclude that it is insufficient to resist the tidal forces that will pull it apart when it gets closer to Mars.
Just as Earth’s moon pulls on the planet in different directions, raising 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. Dismembering it is analogous to pulling apart a granola bar, Mr. Black said, scattering crumbs and chunks everywhere.
The resulting rubble from Phobos — rocks of various sizes and a lot of dust — would continue to orbit Mars and quickly distribute themselves around the planet in a ring. While the largest chunks would eventually spiral into the planet and collide at a grazing angle to produce egg-shaped craters, the majority of the debris would circle the planet for millions of years until these pieces drop onto the planet .
