Spaceflight Insider

Mars may get rings like Saturn in a few million years

Stickney crater on the Martian moon Phobos taken from the Mars Reconnaissance Orbiter or MRO and posted on SpaceFlight Insider

The Martian moon Phobos – may break up and become a ring around the Red Planet in the future. Image Credit: NASA/JPL-Caltech/University of Arizona

When NASA announced on Nov. 10, 2015, that grooves found on the Martian moon Phobos could signal the beginning of the end for the small body, scientists began building research based on the data about the tiny natural satellite’s fate. What some researchers found shows a remarkable possible future for the Martian system.

According to the research paper, “The demise of Phobos and the development of a Martian ring system“, Phobos has two possible futures – breaking up and crashing into Mars or breaking apart into a ring system. The determining factor is dependent on just what Phobos is made of and how strong are the bonds of that material. If Phobos is composed of a mostly rubble-like interior, it will break apart due to increasing tidal forces as the moon slowly spirals closer to the planet.

Benjamin A. Black and Tushar Mittal, the authors of the paper, put forth the argument for the creation of rings around Mars. According to their research, Phobos will break up when its orbit crosses within 1.6 Martian radii, or about 3,370 miles (5,423 km). At that point, the weakest parts of Phobos will begin to give way forming a loose clump of material.

Phobos: Doomed Moon of Mars

Phobos is one of two moons of Mars – the other is Deimos. Image Credit: NASA/JPL-Caltech/University of Arizona

As these objects crash into one another, the material will begin to disburse, creating a proto-ring around Mars. It has been estimated that the distribution of Phobos into a ring will happen rather quickly, with the basic ring structure in place within 50 to 130 orbits of the initial breakup.

“The specific wow moment for us during the study was when we put together our estimates about the strength of Phobos from different approaches, including the strength of fractured rocks, analog material as well as Phobos topography and all of these estimates gave us a very consistent picture regarding whether Phobos would break apart or impact Mars intact,” said Tushar Mittal when we contacted the authors by e-mail. “It was satisfying since at the beginning of the study, we were a bit apprehensive about having enough information to say something meaningful about the future of Phobos.”

Over time, a fully-formed ring could develop composed mostly of smaller objects, sand, and dust. Larger objects would rain out of the ring structure and hit the Martian surface at relatively low velocities and angles. The fully-formed ring will have a life of about 1 to 100 million Martian years – depending on the tidal forces orbit of the debris field.

A ring around Mars may not be the final fate of Phobos, but the evidence points to a breakup. It depends on the strength of Phobos and how much damage the moon has experienced throughout its life. There is evidence that a large object collided with Phobos sometime in its past. Such a collision would have weakened the moon’s internal structure. Such a weakening could be the starting point for the creation of a ring.

“We think that Phobos has already started to fail, and the first sign of this failure is the production of these grooves,” said Terry Hurford of NASA’s Goddard Space Flight Center in Greenbelt, Maryland, one of the original investigators of the Phobos grooves. Hurford and his team presented their finding at the annual Meeting of the Division of Planetary Sciences of the American Astronomical Society at National Harbor, Maryland on Nov. 10.

None of this is going to be happening anytime soon according to the scientists. The current time estimate for Phobos to reach this breaking point is some 20 to 40 million years from now.


Joe Latrell is a life-long avid space enthusiast having created his own rocket company in Roswell, NM in addition to other consumer space endeavors. He continues to design, build and launch his own rockets and has a passion to see the next generation excited about the opportunities of space exploration. Joe lends his experiences from the corporate and small business arenas to organizations such as Teachers In Space, Inc. He is also actively engaged in his church investing his many skills to assist this and other non-profit endeavors.

Reader Comments

Assuming that we (or our descendants) become a truly spacefaring species, it is more likely that Phobos will be mined into oblivion for building materials and propellant long before it ever breaks up to form a ring.

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