The chances of the moon of mars,Phobos disintegrating into a ring of debris around the red planet depend on the satellite’s strength. The force of Mars' gravity is currently dragging the largest of its two moons towards it at a rate of 6.6 feet every 100 years. At that speed, the two bodies are set to collide in 30 to 50 million years or so, but some experts believe the moon won’t last that long. Phobos, which is likely composed of porous, heavily damaged rock, may instead be slowly taken apart by the planet’s gravity over the course of 20 to 40 million years. If that's the case, Mars will end up with a nifty new ring system made from the moon’s remains.