Remember when I wrote that Phobos was dying? Its death may form a ring system around Mars. Unfortunately, none of us are going to see it. New research puts this at happening in about 20 – 40 million years from now.
First, a recap. Earlier this month, NASA scientists said they believe Phobos is showing early signs of “structural failure.” Scientists pointed to long grooves on the moon’s surface as the first sign of Phobos’ eventual breakup. As Mars’ gravity continues tugging on Phobos, it will eventually begin to break apart and form rings around the red planet.
This process lines up with what scientists refer to as “disruption or mass shedding of moons.” Scientists think Neptune’s Triton may also fall apart one day. Even Saturn’s iconic rings may have formed from a large satellite being pulled closer in.
Rings or surface impact?
To figure out which would happen, Benjamin Black (planetary scientists at the University of California, Berkeley) and his colleague Tushar Mittal (also from Berkeley) looked at the strength and density of Phobos. Then, they compared to a model for rock mass strength.
The authors write, “we conclude that Phobos’ inward migration will culminate with division of the satellite according to its internal distribution of strength and damage. The most damaged regions will disperse into a planetary ring.”
And when Phobos begins to fall apart, it will happen quickly. Black told Nature’s Alexandra Witze, “if you were standing on the surface of Mars, you could grab a lawn chair and watch Phobos shearing out and spreading into a big circle.”
But Mars won’t keep its ring. Over the course of millions of years, the ring will slowly descend to the surface according to the researchers calculations.
Future missions may provide more insights
Proposed missions to Phobos could shed some much-needed light on the small moon. Knowing its exact interior makeup and strength would help scientists better understand what may happen in the future.
Phobos could be the last of many moons that met a similar fate.
The authors write:
“We speculate that diminutive Phobos may be the last of many inwardly migrating prograde satellites in our solar system. Numerical simulations of planet formation suggest that Earth-like planets typically experience multiple giant impacts, which may lead to circumplanetary disk formation and a stochastic distribution of planetary spins (including a contingent of slowly spinning primaries). Thus, inwardly migrating satellites – some of which may break up tidally, some of which may collide with their primaries – are likely to be an underappreciated and important component of planetary evolution.”
Ever wonder what Phobos eclipsing the Sun looks like on Mars? You’re in luck. Curiosity captured this in 2013.