Saturn's Rings May Be Ancient After All

Space.com | 6/20/2019 | Mike Wall
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The great Saturn ring debate is far from settled, a new study suggests.

For years, scientists have argued about the age of Saturn's famous rings: Are they ancient, dating to the birth of the planet itself? Or did the ring system form more recently, in just the past hundred million years or so?

Hypothesis - Steam - Years - Papers - Rings

This latter hypothesis has been gaining steam in the last few years, with multiple papers reporting that the rings could be even younger than the dinosaurs. Such studies cite the rings' composition — more than 95% pure water ice — and total mass, which NASA's Cassini mission pegged at about 15.4 million billion metric tons shortly after the probe's epic "grand finale" at Saturn in 2017. (For perspective, 15.4 million billion metric tons is about 40% the mass of the Saturn moon Mimas, which is 250 miles, or 400 kilometers, wide.)

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Figures - Bombardment - Rate - Micrometeoroids - Rings

Given these two figures, and the bombardment rate by micrometeoroids, the rings must be young, the idea goes. After all, old rings should be much more "polluted" with silicates, organic molecules and other compounds.

But there are some serious issues with this interpretation, argues the new study, which was led by Aurélien Crida of the Université Côte d'Azur and the Institut Universitaire de France. For starters, the scientists said, the bombardment rate may vary over time. Maybe it's unusually high right now — due to a (hypothetical) recent collision of distant Kuiper Belt objects, for example — and the rings were polluted much less intensely for most of their history.

Crida - Colleagues - Finale - Cassini - Organics

Crida and his colleagues also note that, during the grand finale, Cassini spotted organics in Saturn's upper atmosphere as well as solid grains in the gap between the gas giant and its innermost ring. This stuff is almost certainly coming from the rings, the researchers...
(Excerpt) Read more at: Space.com
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