You might be surprised to learn that Mars has its own moons, just like the Earth and many other planets in the solar system. According to a report from Discovery News, however, NASA scientists warn that Phobos, the larger of Mars’ two moons, is in serious danger of falling apart.

Phobos has been inching closer and closer to Mars as a result of the planet’s gravitational pull. A recent study presented at the planetary sciences meeting of the American Astronomical Society in Maryland this week reveals that the moon is covered in stress fractures, creating long, shallow grooves on its surface.

Researchers once believed that these grooves were caused by an asteroid impact that hit the moon so hard, it fractured the surface all over. There was a massive impact years ago, which left behind the Stickney crater. The crater is about six-miles wide, nearly half the width of the moon itself.

Scientists found, however, that the cracks did not protrude outward from the crater, but had a separate radius. The theory that small pieces of debris from Mars were causing the grooves was proposed, as the moon orbits the planet at a distance of just 5,800 miles.

According to Terry Hurford, a planetary scientist at NASA’s Goddard Space Flight Center in Maryland, the grooves are more akin to stretch marks than stress fractures. The marks suggest that gravity from Mars has been pulling the moon’s surface, creating the jagged lines on the moon’s surface.

Since Phobos is much smaller than Mars, there is little chance that it will win its game of gravitational tug-of-war. Scientists think that it will take up to 50 million years before the moon is ripped apart by the gravitational force. The tidal deformation observed on Phobos could spell its death.

Computer models show that Phobos is growing increasingly unstable, and its interior structure is beginning to reflect the state of its surface. Researchers will continue to study Phobos to learn more about how it formed and how it has interacted with the Red Planet over time. After all, they still have plenty of time to research the moon before it is destroyed.

A press release from NASA outlining the study’s findings can be read here.