Researchers Find New Evidence that Mars Once Had Massive Ring | Planetary Science, Space Exploration – Sci-News.com

Mars had a massive ring system several billion years ago, according to new research from the SETI Institute and Purdue University.

An artists impression of a ringed Mars. Image credit: Tushar Mittal.

Mars has two small satellites, Phobos and Deimos, discovered by the American astronomer Asaph Hall at the Naval Observatory on August 18, 1877.

They are thought to have formed from debris ejected by a single colossal impact onto early Mars.

Although these moons are small, their peculiar orbits hide important secrets about their past.

The fact that Deimos orbit is not exactly in plane with Marss equator was considered unimportant, and nobody cared to try to explain it, said Dr. Matija uk, a research scientist at the SETI Institute.

But once we had a big new idea and we looked at it with new eyes, Deimos orbital tilt revealed its big secret.

In 2017, Purdue Universitys Dr. David Minton and his student Andrew Hesselbrock noticed that the Martian inner moon, Phobos, is losing height as its tiny gravity is interacting with the looming Martian globe.

In several dozens of million years, Phobos orbit will drop too low, and Martian gravity will pull it apart to make a ring around the planet.

Mars is kept company by two cratered moons an inner moon named Phobos and an outer moon named Deimos. Image credit: NASA / JPL-Caltech / Malin Space Science Systems / Texas A&M University.

The team proposed that over billions of years, generations of Martian moons were destroyed into rings. Each time, the ring would then give rise to a new, smaller moon to repeat the cycle over again.

This cyclic Martian moon theory has one crucial element that makes Deimos tilt possible: a newborn moon would move away from the ring and Mars. Which is in the opposite direction from the inward spiral Phobos is experiencing due to gravitational interactions with Mars.

An outward-migrating moon just outside the rings can encounter a so-called orbital resonance, in which Deimos orbital period is three times that of the other moon. These orbital resonances are picky but predictable about the direction in which they are crossed.

Only an outward-moving moon could have strongly affected Deimos, which means that Mars must have had a ring pushing the inner moon outward.

This moon may have been 20 times as massive as Phobos, and may have been its grandparent existing just over 3 billion years ago, which was followed by two more ring-moon cycles, with the latest moon being Phobos, Dr. uk and colleagues said.

Their findings will be published in the Astrophysical Journal Letters.

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Matija uk et al. 2020. Evidence for a Past Martian Ring from the Orbital Inclination of Deimos. ApJL, in press; arXiv: 2006.00645

This article is based on text provided by the SETI Institute.

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Researchers Find New Evidence that Mars Once Had Massive Ring | Planetary Science, Space Exploration - Sci-News.com