The Mystery Of Crusty Brown Mars' Depleted Ring

The Mystery Of Crusty Brown Mars' Depleted Ring

Mars is nothing short of an enigma to us Earthlings. 

But to add some fuel to the cosmic mystery of Mars, there's evidence showing it may have previously sported a lustrous brown ring of rubble. 

Mars has twin moons, Deimos and Phobos, with Deimos being the smaller. Little Deimos harbours a naughty little secret: it orbits Mars with a slight tilt compared to the planets equator. 

What does this have to do with a brown Mars ring?

It could be the results of gravitational forces caused by a planetary ring.


Deimos, a moon of Mars that could have begun life as a ring of dust


You might be surprised by hearing this, but ring systems aren't rare. 

When we think of rings, we think of Saturns immensely prominent circular sails. 

BUT, half the planets in our solar system sport wonderfully unique rings. 

Saturn obviously.
Even Jupiter has a faint ring, believe it or not.

And, of course, Uranus has a ring to it. 





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Only recently, the theory of Mars having a ring has been tested and hypothesised by a pair of researchers through simulations.
Their tests calculated the likelihood of Phobos emerging as a cloud of debris after an asteroid impact on Mars.

This sents said debris hurtling into space, which Mars' gravity held onto and formed a ring, before collecting together over time to form Phobos and most likely its twin, Deimos.

"The fact that Deimos' orbit is not exactly in-plane with Mars' equator was considered unimportant, and nobody cares to try to explain it. But once we had a big new idea and we looked at it with new eyes, Deimos' orbital revealed its big secret." astronomer Matija Cuk of the SETI institute said.

By this theoretical model, it could be viable to speculate Earth's moon once started as a ring, or Saturn's rings will eventually clump together over millions of years.

However, this is entirely speculation.


Ancient Mars has been theorised to have had rings


While Deimos' orbit isn't large, at just 1.8 degrees from Mars' equator, its orbital path is fairly normal - taking 30 or so hours and with very little eccentricity (meaning, the amount it deviates from a perfect circle).

Hence why no one thought there was something else going on. 

What we've now realised is Phobos is much closer to Mars than first thought and gradually creeping closer by 1.8cm per year. 

Within 100 million years, Phobos will reach the Roche Limit, which dictates the moon is close enough to be torn to shreds by Mars' tidal forces.

Most of the debris will become a fainter ring again, and some will become smaller chunks of moon to begin orbiting Mars much like its predecessor.

Basically, the planet draws the dust in to form a ring and pushes the chunks out to form moons. 

According to research, this type of moon/ring recycling has happened before, several times in fact and has lead to a greater theory including where Mars' other moon Deimos comes in. 


The orbital path of Deimos, a moon on Mars


Using a numerical series of simulations, Cuk and his team found Phobos moving outward from Mars after a Roche Limit event would affect the orbital path Deimos.

This neatly explains in numerical terms how Deimos became the moon we know today. 

After the Late Heavy Bombardment of asteroids around 3.9 billion years ago which would have crushed any moons around Mars and beginning the cycle of a ring to a moon - possibly twice - before creating the moon we know as Deimos. 

Around 3.5 billion years ago is the best estimation which aligns with other theoretical models where Mars' housed an inner moon with 20 times the mass of Phobos.

The current estimate of Phobos' age is around 200 million years, and with Japan's Space Agency (JAXA) planning a probe to the brown town of Mars to Phobos in 2024, we might see some evidence that supports this theory. 

Phobos surface samples can be dated once collected and analysed on Earth to see if they're no more than a few hundred million years old, which would provide some validation to the theory of Mars ring.

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