https://www.sciencenews.org/article/saturn-ring-rain-surprising-cocktail-chemicals
The "ring rain" of material falling from Saturn's rings into the planet's atmosphere is a much more intense, contaminated downpour than scientists thought.
For decades, astronomers have suspected that Saturn's rings pelt the planet with grains of water ice, but some of the final observations from NASA's Cassini spacecraft provide the first detailed views of these celestial showers (SN: 4/14/18, p. 6). Ring rain is highly contaminated with organic matter and other molecules, and hammers Saturn at thousands of kilograms per second, researchers report in the Oct. 5 Science. Understanding the rain's surprising quantity and quality could help clarify the origins and evolution of Saturn's rings.
Researchers analyzed data collected by Cassini's Ion Neutral Mass Spectrometer during the spacecraft's final few orbits in 2017, as it sailed through the gap between Saturn and its innermost ring, known as the D ring (SN Online: 9/15/17). Water constituted only about 24 percent of the material tumbling from Saturn's ring system into its atmosphere; the rest was methane, carbon monoxide, dinitrogen, ammonia, carbon dioxide and fragments of organic nanoparticles.
The ring rain's diverse chemical composition "was a big surprise," because remote observations show that Saturn's ring system, on the whole, is almost entirely water ice, says Cassini project scientist Linda Spilker of NASA's Jet Propulsion Laboratory in Pasadena, Calif., who wasn't involved in the study. Researchers aren't sure why ring rain is so deprived of water.
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Saturn is famous for its lovely rings, but a new study suggests the planet has spent most of its 4.5 billion years without them. That's because the rings are likely only 10 million to 100 million years old, according to a newly published report [open, DOI: 10.1126/science.aat2965] [DX] in the journal Science that's based on findings from NASA's Cassini probe.
Cassini spent some 13 years orbiting Saturn before plunging down and slamming into its atmosphere. During its final orbits, the spacecraft dove between the planet and its rings. That let scientists measure the gravitational effect of the rings and get a good estimate of the ring material's mass.
What they found is that it's only about 40 percent of the mass of Saturn's moon Mimas, which is way smaller than Earth's moon. This small mass suggests that the rings are relatively young. That's because the rings seem to be made of extremely pure water ice, suggesting that the bright white rings have not existed long enough to be contaminated by the bombardment of messy, dirty comets that would be expected to occur over billions of years. Some scientists thought it was possible that darker debris from comets might lie beneath the bright ice, undetectable to their instruments, but this new study shows that isn't the case.
Related: Saturn's 'Ring Rain' is a Surprising Cocktail of Chemicals
Most of Saturn's Rings Could Disappear Within 100 Million Years
(Score: 2) by DannyB on Wednesday October 10 2018, @06:30PM (9 children)
I skimmed the article but didn't notice an obvious answer for this.
If the ring rain moves materials from the rings to the planet's atmosphere, then wouldn't the rings eventually be depleted? Is there some sort of cycle that moves materials back out into the ring from the atmosphere? If the rings are not replenished, how large are they and how long would it take to deplete them if it hasn't happened yet in 4 billion years? And . . . what might the rings have originally looked like?
(insert today's selected conspiracy theory about the ring rain containing organic molecules)
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(Score: 4, Funny) by maxwell demon on Wednesday October 10 2018, @06:52PM (2 children)
Didn't you notice the discrepancy? On one hand they claim it's organic matter, on the other hand it is full of chemicals. While everyone knows that organic means containing no chemicals! ;-)
The Tao of math: The numbers you can count are not the real numbers.
(Score: 0) by Anonymous Coward on Wednesday October 10 2018, @07:28PM (1 child)
I dunno, I got organic chicken breast and it was like a different animal than the non-organic (but also 2-3x more expensive). I think organic mostly means "premium" at this point.
(Score: 2) by DannyB on Wednesday October 10 2018, @09:41PM
Apple should market the iPhone as organic.
New Improved! Soylent Green -- made from all natural free range ingredients!
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(Score: 2, Interesting) by Anonymous Coward on Wednesday October 10 2018, @06:55PM
We'll probably hear about the electric universe, but I wanna see this worked up as a weather war conspiracy. Maybe chemtrails are evidence of Earth's ring system that NASA wants to hide from the public!
(Score: 3, Funny) by Gaaark on Wednesday October 10 2018, @07:39PM
"today's selected conspiracy theory about the ring rain "
Yo' momma WAS so fat...that she blew apart after eating one small chocolate (it was wafer thin) and now she's orbiting--
...
......yeah... sorry....
--- Please remind me if I haven't been civil to you: I'm channeling MDC. ---Gaaark 2.0 ---
(Score: 1, Informative) by Anonymous Coward on Wednesday October 10 2018, @09:12PM
Yes, presumably most of the mass of the rings will fall into the planet eventually. The article says "thousands of kilograms per second" rain down. Let's arbitrarily say that's about 3000kg/sec since that makes a nice number of 100 million tonnes per year.
According to wikipedia [wikipedia.org], "based on Voyager observations, the total mass of [Saturn's] rings was estimated to be about 3 × 10^19 kg."
That's 30 quadrillion tonnes. If the rate remains constant at 100 million tonnes per year, it should all be gone in about half a billion more years.
The origin of the rings is not well understood so we don't really know how long they've been there.
(Score: 1) by Barenflimski on Wednesday October 10 2018, @09:32PM (1 child)
It seems obvious to me that its aliens. Clearly there was a huge war a long time ago. They blasted the moons apart too. This is why Saturn is so gaseous, and there are organic remains in a ring around the planet. It was all blown up.
(Score: 2) by takyon on Wednesday October 10 2018, @10:32PM
The peace treaty was signed on Titan.
[SIG] 10/28/2017: Soylent Upgrade v14 [soylentnews.org]
(Score: 2) by c0lo on Wednesday October 10 2018, @09:38PM
Not until the fat lady sings, which means quite a long time: they found 'Der Ring des Nibelungen' cycle.
https://www.youtube.com/watch?v=aoFiw2jMy-0 https://soylentnews.org/~MichaelDavidCrawford
(Score: 0) by Anonymous Coward on Wednesday October 10 2018, @08:02PM
Some days my own "ring rain" would suit the exact description in the story subject.