Estimated read time: 1-2 minutes
This archived news story is available only for your personal, non-commercial use. Information in the story may be outdated or superseded by additional information. Reading or replaying the story in its archived form does not constitute a republication of the story.
GREENBELT, Md. — The process could take 30 to 50 million years, but NASA says Mars' moon is falling apart.
Phobos, the moon that tightly orbits the red planet, is already showing signs of distress. On Tuesday, NASA researchers said the long, shallow grooves that line the moon's surface are warning signs of what is to come.
"We think that Phobos has already started to fail, and the first sign of this failure is the production of these grooves," NASA researcher Terry Hurford said in a statement.
The larger of Mars' two moons, Phobos is unique in our solar system because of how close it is to the surface of the planet it orbits. It is located 3,700 miles away from the red planet — nearer than any other moon and planet pair — and Mars' gravity field is pulling it in at a rate of 6.6 feet per century.
Phobos, moon of Mars, will ultimately be destroyed by the planet's gravity. https://t.co/hQxkZx0pRrpic.twitter.com/faUNf0rC0N
— NASA Solar System (@NASASolarSystem) November 11, 2015
The resulting tidal forces from the gravitational pull of Mars and Phobos created the long grooves, which the NASA team described as being "stretch marks." While researchers long believed Phobos was mostly solid, they now suspect "the interior of Phobos could be a rubble pile, barely holding together, surrounded by a powdery regolith about 330 feet thick." A weaker interior would explain why the stress from tidal forces could cause the moon's structure to fail.
Phobos might not be the only moon in the solar system experiencing these problems, according to NASA. Researchers said cracks on Neptune's moon Triton looks similar to Phobos's grooved surface.