WEBVTT - Will Saturn's Rings Last Forever?

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<v Speaker 1>Welcome to brain Stuff from How Stuff Works, Hey, brain Stuff,

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<v Speaker 1>Lauren Vogelbam Here, humanity exists at a very special time

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<v Speaker 1>in our Solar System's history, the era of Saturn's rings.

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<v Speaker 1>In the next hundred million years, Saturn's rings will completely disappear,

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<v Speaker 1>and planetary scientists have realized that it acquired those rings

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<v Speaker 1>only very recently. During the Cassini missions final months at Saturn,

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<v Speaker 1>the NASA spacecraft carried out a series of daring orbits

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<v Speaker 1>through the space between the planet's cloud tops and innermost

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<v Speaker 1>edge of its rings. This so called Grand Finale signaled

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<v Speaker 1>that the end was nigh for the probe, and on

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<v Speaker 1>September it burned up in the gas giant's atmosphere, bringing

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<v Speaker 1>a spectacular thirteen years of science in Saturn's orbit to

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<v Speaker 1>a poignant close. The spacecraft was low on fuel, and

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<v Speaker 1>to avoid an accidental crash into what a Saturn's potentially

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<v Speaker 1>habitable moons, NASA had long ago decided that the best

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<v Speaker 1>way to dispose of the mission was to burn it

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<v Speaker 1>up in Saturn's upper atmosphere. The agency wanted to avoid

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<v Speaker 1>earthly contamination on these pristine alien environments. Before its fiery death, However,

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<v Speaker 1>Cassini took unprecedented measurements of the mysterious ring gap region

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<v Speaker 1>to reveal some surprising ring dynamics. The mission scientists expected

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<v Speaker 1>to detect some whispy elemental gases in this empty region,

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<v Speaker 1>Cassini's particle instrumentation found a smorgas board of elements and

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<v Speaker 1>molecules raining from the rings down to the planet's atmosphere.

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<v Speaker 1>They estimated around ten tons of material that's about nine

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<v Speaker 1>thousand kilos is falling onto Saturn from the rings per second.

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<v Speaker 1>That means that Saturn's rings will eventually disappear and will

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<v Speaker 1>have existed only for a short blip of Saturn's four

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<v Speaker 1>billion year lifespan. So far, researchers have used Cassini's ring

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<v Speaker 1>dives to estimate when Saturn acquired its famous rings. When

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<v Speaker 1>Cassini zipped through Saturn's ring plane, mission managers allowed the planet,

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<v Speaker 1>its rings and moons to gravitationally tug at these speeding spacecraft.

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<v Speaker 1>These extremely slight tugs resulted in tiny change is in

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<v Speaker 1>the probe's trajectory, which could be precisely measured. Those changes

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<v Speaker 1>allowed scientists, too, for the first time, make a very

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<v Speaker 1>good measurement of how much mass is holed up in

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<v Speaker 1>Saturn's rings. After analyzing the final set of orbits, However,

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<v Speaker 1>the extent to which Cassini's trajectory was deflected initially didn't

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<v Speaker 1>make sense. It didn't match the predictions by theoretical models.

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<v Speaker 1>It turned out the Cassini's motion was being additionally altered

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<v Speaker 1>by massive flows of material at Saturn's equator, inside its

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<v Speaker 1>thick atmosphere about six thousand miles or nearly ten thousand

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<v Speaker 1>kilometers deep. These massive flows are moving about four percent

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<v Speaker 1>slower than the visible upper atmospheric clouds, causing a gravitational

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<v Speaker 1>anomaly that wasn't predicted. Cassini Project scientist Linda Spilker of

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<v Speaker 1>NASA's Jet Propulsion Laboratory set in a statement, the discovery

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<v Speaker 1>of deeply rotating layers is a surprising revelation about the

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<v Speaker 1>internal structure of the planet. The question is what causes

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<v Speaker 1>the more rapidly rotating part of the atmosphere to go

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<v Speaker 1>so deep and what does that tell us about Saturn's interior. However,

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<v Speaker 1>with this normally partially explained, scientists were free to measure

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<v Speaker 1>the gravitational influence of Saturn's rings, and thus measure their mass.

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<v Speaker 1>The researchers estimate that the total mass of Saturn's rings

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<v Speaker 1>is approximately that of Saturn's moon Mimus. Considering Mimus is

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<v Speaker 1>two thousand times smaller than Earth's spoon, there certainly isn't

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<v Speaker 1>a lot of material in Saturn's rings. Scientists had previously

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<v Speaker 1>relied on density waves or ripples through the rings caused

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<v Speaker 1>by the motion of the sixty two moons in Saturn's

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<v Speaker 1>orbit to estimate ring mass. Although these estimates were also low,

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<v Speaker 1>astronomers have always assumed there was some kind of hidden

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<v Speaker 1>mass in large blocks of material that remained unseen. Now,

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<v Speaker 1>with the precision measurements made by Cassini's final orbits, we

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<v Speaker 1>know that there is no hidden mass. The lower the

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<v Speaker 1>mass of the rings, the younger they are, and because

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<v Speaker 1>they are predominantly made of ice, if they were older,

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<v Speaker 1>the ring material would have become contaminated by interplanetary debris

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<v Speaker 1>dulling them. In. Saturn's rings, as we're acutely aware, are

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<v Speaker 1>beautifully bright. Previous estimates of ring age have been far

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<v Speaker 1>ranging from four point five billion years the leftovers of

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<v Speaker 1>when Saturn itself was forming, to a few tens of

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<v Speaker 1>billion years, but with this new finding in hand, it

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<v Speaker 1>looks like the rings are very young, formed less than

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<v Speaker 1>one hundred million years ago and perhaps as recently as

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<v Speaker 1>ten million years ago. Where the rings came from remains

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<v Speaker 1>more of a mystery. It's possible that an icy object

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<v Speaker 1>from the Kuiper Belt or an arrant comet became entwined

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<v Speaker 1>in Saturn's gravitational field and succumbed to the planet's powerful tides,

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<v Speaker 1>was ripped apart and eventually ground down to create the

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<v Speaker 1>banded rings we know and love today. Although Saturn's rings

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<v Speaker 1>will be gone in a hundred million years, it doesn't

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<v Speaker 1>mean that our Solar systems ringed planet days are gone forever.

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<v Speaker 1>If Saturn can create them, there's little reason why Jupiter, Neptune,

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<v Speaker 1>or Uranus can't shred anice the object create another bright

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<v Speaker 1>ringed planet display in the distant future. Today's episode was

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<v Speaker 1>written by Ian O'Neil and produced by Tyler Clang for

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<v Speaker 1>iHeart Media and How Stuff Works. For more on this

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<v Speaker 1>and lots other bright topics, visit our home planet how

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<v Speaker 1>Stuff Works dot com. MHM