Mars' gravitational pull is slowly tearing apart one of its two moons, Phobos, which will lead to the space rock's inevitable destruction. But instead of disappearing into space, the leftover materials from Phobos may form a ring around the Red Planet, similar to the one around Saturn.
Scientists only learned about the dramatic fate of Phobos earlier this month, thanks to new models of the moon's surface. Researchers were trying to figure out the origins of numerous shallow grooves on Phobos' exterior, once believed to be fractures leftover from when Phobos first formed. More recently, researchers thought the markings were caused by the impacts of materials that first collided with Mars and then blasted off the Martian surface.
Mars' gravitational pull is slowly tearing the moon apart
But computer modeling revealed that these grooves are actually signs that Mars' gravity is a fatal embrace. Phobos is closer to its host planet than any other moon in the solar system, and it's getting pulled 6.6 feet closer every hundred years. That means the grooves are like "stretch marks" caused by Mars' tidal forces — an indication that Phobos is slowly deforming.
Now, in a new paper published today in the journal Nature Geosciences, scientists determined what would happen to the doomed moon once gravity finally tears it apart. Using observational data and modeling, the research team figured out that Phobos is composed of weak, heavily damaged materials that will break apart into tiny pieces and form a ring in 20 to 40 million years. The ring will be about the same density of Saturn's ring and last for an additional 1 to 100 million years. If any larger pieces break off from Phobos, they will likely fall to the surface of Mars and cause impact craters.
Learning more about Phobos is helpful, especially since it could help pave the way for a crewed Mars mission. The Planetary Society has suggested sending humans to Phobos first, before sending them to the surface of the Red Planet.