Saturn’s Iconic Rings: Young and Ephemeral, NASA Studies Show

Three recent studies by scientists at NASA’s Ames Research Center in California’s Silicon Valley examine data from NASA’s Cassini mission and provide evidence that Saturn’s rings are both young and ephemeral – in astronomical terms, of course.

The new research looks at the mass of the rings, their “purity,” how quickly incoming debris is added, and how that influences the way the rings change over time. Put those elements together, and one can get a better idea of how long they’ve been around and the time they’ve got left.

The rings are almost entirely pure ice. Less than a few percent of their mass is non-icy “pollution” coming from micrometeoroids, such as asteroid fragments smaller than a grain of sand. These constantly collide with the ring particles and contribute debris to the material circling the planet. The rings’ age has been hard to pin down, because scientists hadn’t yet quantified this bombardment in order to calculate how long it must have been going on.

Now, one of the three new studies^[1] It gives a better idea of ​​the total rate of arrival of non-glacial material and thus how much “polluted” the rings must have been since their formation. This research, conducted by the University of Colorado at Boulder, also indicates that micrometeorites don’t arrive as fast as scientists think, which means that Saturn’s gravity may pull material into the rings more efficiently. This evidence adds that the rings could not have been exposed to this cosmic hailstorm for more than a few hundred million years – a small fraction of the 4.6 billion-year age of Saturn and the solar system.

This conclusion is supported by the second article,^[2] Led by Indiana University, which takes a different angle on the constant beating of the rings by small space rocks. The study authors identified two things that have been largely ignored in the research. Specifically, they examined the physics that govern the long-term evolution of the rings and found that two important components are the bombardment of micrometeorites and the way debris from these collisions is distributed through the rings. Taking these factors into account shows that the rings could have reached their current mass in a few hundred million years. The results also suggest that because they are so young, they likely formed when unstable gravitational forces within the Saturnian system destroyed some of its icy moons.

“The idea that Saturn’s iconic major rings might be a recent feature of our solar system has been controversial,” said Jeff Causey, an Ames researcher and co-author of one of the recent papers. But our new findings complement a trio of Cassini measurements. Which makes this discovery difficult to avoid. Cozzi was also a multidisciplinary scientist on the Cassini mission to Saturn’s rings.

So Saturn may have been around for more than 4 billion years before adopting its current appearance. But how long can you count on the beautiful rings we know today?

The Cassini mission discovered that the rings are rapidly losing mass as material has fallen from the planet’s deepest regions. Third paper^[3] Also, led by Indiana University, determines for the first time the rate of drift of ring material in this direction — and meteorites again play a role. Their collisions with existing ring particles and the way the resulting debris is thrown outward combine to create a kind of conveyor belt for motion that carries material from the ring to Saturn. By calculating what all those streaming particles mean for their eventual disappearance from the planet, researchers have come up with bad news for Saturn: It could lose its rings in the next hundreds of millions of years.

“I think these results tell us that the constant bombardment with all this foreign debris is not only contaminating the planetary rings, but they should also be shrinking over time,” said Paul Estrada, a researcher at Ames and co-author of the three studies. “Maybe[{”attribute=””>Uranus’and[{”attribute=””>Uranus’andNeptune