Sad as this news is, it may finally help answer a longstanding question: Did the planet form with its rings, or did they materialize later?
The fate of the rings looks even grimmer considering research published earlier this year using Cassini data, which looked at a different, still-more-voluminous, type of infall from Saturn's rings that's descending into the planet.
The space agency says the rings are being pulled into Saturn by gravity as a dusty rain of ice particles under the influence of Saturn's magnetic field. They detected some unusual changes in Saturn's ionosphere, density variations in the rings themselves, and three dark bands circling Saturn at mid-northern latitudes.
Every half hour, enough water is drained from the rings to fill an Olympic-sized swimming pool, O'Donoghue said in a NASA press release. That rate, combined with the current mass of Saturn's rings, is what lets scientists calculate that 300-million-year life expectancy, although the large range on the infall calculation means there's quite a bit of uncertainty about the rings' lifetime.
"This is relatively short, compared to Saturn's age of over 4 billion years", said O'Donoghue.
The Cassini spacecraft captured this stunning view of Saturn and its rings on April 25, 2016.
Scientists estimate the rings could be gone in 300 million years, but they could vanish even faster.
Research has already shown that Saturn's rings are fairly young.
The study indicates the rings were formed around the planet less than 100 million years ago, whereas previous research indicated they were some four billion 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".
Dr James O'Donoghue, of NASA's Goddard Space Flight Centre in Greenbelt, Maryland, and his colleagues have used instruments attached to the Keck telescope in Hawaii to discover the phenomenon.
"We know that it's bumping material out of the rings at least 10 times faster than we thought", said Thomas Cravens, co-author of one of the October studies and a University of Kansas professor of physics and astronomy.
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. Instead, they were fastened onto Saturn within the last few hundred million years - during the time of the dinosaurs. The diameter of the ring system is huge: 170,000 miles, or nearly three-quarters of the distance from the Earth to the moon.
The spacecraft took a census of the particles it encountered that were falling toward the planet; the amount of ring rain Cassini caught is "completely consistent" with O'Donoghue's measurements, Spilker said.