Published: Wed, December 19, 2018
Sci-tech | By Patricia Wade

Saturn Losing Its Rings at Quicker Rate Than Projected

Saturn Losing Its Rings at Quicker Rate Than Projected

The rings are kept in place by a combination of factors: Saturn's gravity pulls them in, but the planet's spin in combination with the rings' orbital velocity, tries to fling them back out into space.

The rings are mostly composed of lumps of water ice that vary in size from microscopic grains to boulders of several yards across, the space agency said.

It ain't St. Louis without the Gateway Arch, it ain't Mount Rushmore without the Presidents, and it sure ain't Saturn without the rings.

In this artist's impression, charged water molecules spiral around Saturn's magnetic field lines, flowing from the rings to the planet's upper atmosphere.

"What we're seeing is something on the order of about a ton and a half per second", said James O'Donoghue of NASA's Goddard Space Flight Center, in Greenbelt, Maryland, who reported the conclusions Monday in the journal Icarus. "This is relatively short, compared to Saturn's age of over 4 billion years".

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Leading up to the September 15, 2017 "Grand Finale" of NASA's Cassini spacecraft, when the mission team plunged the probe down into the planet's atmosphere, the spacecraft was sent on a trajectory to slip between the planet and its rings. The ring rain that falls into the gas giant is so abundant that the icy bands could disappear in 300 million years, or even sooner. But they are raining so much water onto the planet that in 300 million years they could rain themselves almost out of existence, leaving Saturn startlingly ringless. The rings, the thinking at that point went, would likely be gone in a maximum of 300 million years or, in a worst case scenario, just 100 million.

'It is possible, in the age of the dinosaurs, that Saturn's rings were even larger and brighter than we see them today. The NASA team now estimates the rings are only about 100 million years old. With its iconic rings, you can pick Saturn out in an instant, but if NASA scientists are right, we might actually be watching the planet's most eye-catching feature disappearing right in front of us. "However, if rings are temporary, perhaps we just missed out on seeing giant ring systems of Jupiter, Uranus and Neptune, which have only thin ringlets today!"

This video explores how Saturn is losing its rings at a rapid rate in geologic timescales and what that reveals about the planet's history. O'Donoghue and his co-authors didn't include that infall in the estimates presented in their paper, but suggested in an accompanying statement that the two phenomena combined could gorge through the rings in more like 100 million years.

Once there, the icy ring particles vaporize and the water can react chemically with Saturn's ionosphere. This is where Saturn's magnetic field intersects the orbit of Enceladus, a geologically active moon that is shooting geysers of water ice into space, indicating that some of those particles are raining onto Saturn as well.

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