Mars' largest moon, Phobos, is slowly falling toward the planet. But rather than smash into the surface, it will likely be shredded and the pieces strewn about the planet in a ring much like the one encircling Saturn, according to two scientists at the University of California - Berkeley. As Phobos gets closer to the planet, the force of gravity will be enough to actually pull the moon apart. This is because Phobos is highly fractured, with lots of pores and rubble. Dismembering it will be analogous to pulling apart a granola bar, scattering crumbs and chunks everywhere. Though inevitable, the demise of Phobos is not imminent. It will probably happen in 20 to 40 million years, leaving a ring that may persist for up to 100 million years.