Surprising chemical complexity of Saturn's rings changing planet's upper atmosphere

October 4, 2018, University of Kansas
A new paper in Science, shows the innermost D ring of the gas giant is hurling dust grains coated in its chemical cocktail into the planet's upper atmosphere at an extraordinary rate as it spins. Over long timescales, the researchers say this infalling material may change the carbon and oxygen content of the atmosphere. Credit: NASA

Political humorist Mark Russel once joked, "The scientific theory I like best is that the rings of Saturn are composed entirely of lost airline luggage."

Well, there's no luggage, it turns out. But a new study appearing in Science based on data from the final orbits last year of NASA's Cassini spacecraft shows the rings of Saturn—some of the most visually stupendous objects in the universe—are far more chemically complicated than previously was understood.

Furthermore, the paper shows the innermost D ring of the gas giant is hurling dust grains coated in its chemical cocktail into the planet's at an extraordinary rate as it spins. Over long timescales, the researchers say this infalling material may change the carbon and oxygen content of the .

"This is a new element of how our solar system works," said Thomas Cravens, professor of physics & astronomy at the University of Kansas and a co-author of the new paper. "Two things surprised me. One is the chemical complexity of what was coming off the rings—we thought it would be almost entirely water based on what we saw in the past. The second thing is the sheer quantity of it—a lot more than we originally expected. The quality and quantity of the the rings are putting into the atmosphere surprised me."

Cravens is a member of Cassini's Ion and Neutral Mass Spectrometer (INMS) team. During Cassini's "Grand Finale" plunge into Saturn's innermost ring and upper atmosphere in 2017, the aboard the probe sampled chemicals at altitudes between Saturn's rings and atmosphere.

More than simply water, the INMS found the rings to be composed of water, methane, ammonia, carbon monoxide, molecular nitrogen and carbon dioxide.

During Cassini's 'Grand Finale' plunge into Saturn's innermost ring and upper atmosphere in 2017, the mass spectrometer aboard the probe sampled chemicals at altitudes between Saturn's rings and atmosphere. Credit: NASA
"What the paper is describing is the environment in the gap between the inner ring and upper atmosphere, and some of the things found were expected, such as water," Cravens said. "What was a surprise was the mass spectrometer saw methane—no one expected that. Also, it saw some carbon dioxide, which was unexpected. The rings were thought to be entirely water. But the innermost rings are fairly contaminated, as it turns out, with organic material caught up in ice."

A further new finding from Cassini's mass spectrometer showed large amounts of the chemical brew from Saturn's D ring is flung into the planet's upper atmosphere by the ring spinning faster than the planet's atmosphere itself.

"We saw it was happening even though it's not fully understood," the KU researcher said. "What we saw is this material, including some benzine, was altering the uppermost atmosphere of Saturn in the equatorial region. There were both grains and dust that were contaminated."

Cravens said the findings could cast new light on mechanisms underpinning our solar system as well as other solar systems and exoplanets—and also prompt a host of new scientific questions.

"This could help us understand, how does a planet get rings? Some do, some don't," he said. "What's the lifetime of a ring? And what's replenishing the rings? Was there a time when Saturn didn't have rings? How did that composition get into there in the first place? Is it left over from the formation of our solar system? Does it date back to proto pre-solar nebula, the nebula that collapsed out of interstellar media that formed the sun and planets?"

According to Cravens, the higher-than-expected rate of material being expelled from Saturn's D Ring into the planet's upper atmosphere, or ionosphere, is sufficient that astronomers now think the lifespan of the ring may be briefer than previously estimated.

A video clip to animate the trajectory of a charged nanograin ejected from Saturn's main rings under the influence of Saturn's gravity and magnetic field. Credit: H.-W. Hsu and the Cassini Cosmic Dust Analyser team
"Because of this data, we now have shortened the lifetime of inner rings because of the quantity of material being moved out—it's much more than we thought before," Cravens said. We know that it's bumping material out of the rings at least 10 times faster than we thought. If it's not being replenished, the rings aren't going to last—you've got a hole in your bucket. Jupiter probably had a ring that evolved into the current wispy , and it could be for similar reasons. Rings do come and go. At some point they gradually drain away unless somehow they're getting new material."

Assisted by KU graduate and undergraduate students, a first stage of Cravens' work involved sorting and cleaning raw data from Cassini's INMS instrument.

"The raw data came through from our instrument on Cassini to deep-space antennas to NASA's Jet Propulsion Laboratory and then to computers at the Southwest Research Institute in San Antonio where Hunter Waite, the first author, is based," he said.

But Cravens' main contribution involved interpreting that data with a focus on how materials from the rings are altering Saturn's ionosphere. Cravens and his colleagues report the influx of chemicals from the rings change Saturn's equatorial ionospheric chemistry by converting the hydrogen ions and triatomic hydrogen ions into heavier molecular ions, depleting the planet's ionospheric density.

"My interest was in the ionosphere, the charged-particle environment, and that's what I focused on," Cravens said. "This gunk coming in chews up a lot of the ionosphere, affects its composition and causes observable effects—that's what we're trying to understand now. The data are clear, but explanations are still being modeled and that will take a while. The material is coming into Saturn at high speeds because the rings are moving faster than the atmosphere quite a bit. It doesn't just drop in gently. It comes flying in there like a satellite re-entering our own planet. These dust grains moving at satellite speed, depositing energy that can dissociate the atmosphere. Per atom, it's pretty energetic stuff because of the speed differentiation between the rings and the atmosphere. We think it may be heating the upper atmosphere, changing its composition."

Explore further: Image: Saturn's inside-out rings

More information: J.H. Waite el al., "Chemical interactions between Saturn's atmosphere and its rings," Science (2018). science.sciencemag.org/cgi/doi … 1126/science.aat2382

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rrwillsj
2 / 5 (5) Oct 04, 2018
A recent article claimed that observed early star systems. In first few million years of existence. Their proto-planetary disks do not contain enough material to become what we would recognize as planets.

The researchers speculated that the formation of recognizable planets might take a lot longer than astronomers had believed. Maybe even billions of years to form what we are use to seeing?

Which brings us back to Saturn, For us to speculate possible futures. In a few billion years, as our Sun percolates into a Red Giant? What sort of effect it would have on the Gas Giants. And could it energize up some really exotic biospheres?

The big problem with actually discovering any examples? Is the time to collect a planet together, then begin the tediously lengthy proto-biochemical processes to kickstart even the simplest
micro-organism.

We are Sooners and the Universe is still too young, too primitive, too undeveloped, too disorganized during this early epoch.
jonesdave
2.3 / 5 (6) Oct 04, 2018
The researchers speculated that the formation of recognizable planets might take a lot longer than astronomers had believed. Maybe even billions of years to form what we are use to seeing?


I don't believe so. The suggestion was that they may have formed much more quickly than thought.

rrwillsj
1 / 5 (4) Oct 04, 2018
jonesdave, My opinion is that the research vividly displays that the sparsity of material in the earliest phase of the observed proto-planetary disks. Before three million years of age.

https://phys.org/...lanet.ht

Perhaps your conjecture is more correct than mine for the following time period? That after that first phase, there was a quick build-up of planetary material? But that is as speculative as my interpretation, without confirming evidence.

It is my opinion, based solely on these recent findings. That planetary formation is a lot more uncertain and sporadically random than we want to accept. Over a much longer period of time.

What is happening to Saturn during this stage of it's existence is one sample.

Another, I think, is the continuing bombardment of the Earth's crust with the phosphates from iron-nickel meteorites. Constantly fertilizing this planet's established biosphere.
torbjorn_b_g_larsson
3 / 5 (4) Oct 04, 2018
My opinion is that the research vividly displays that the sparsity of material in the earliest phase of the observed proto-planetary disks.


Your opinion does not correspond to facts, the point is that the observations cannot conclusively demonstrate a sparsity. To quote an article from a well reviewed "science clearing house" (science advocate organization):

"A relatively new, well-liked theory called pebble accretion offers a way. In this theory, many tiny pebbles and dust grains quickly glom on to larger objects, suggesting planets can grow faster when they grow by small degrees. Batygin said much of planetary formation research is headed in this direction, and Manara's new study points the same way."

[ https://www.quant...0181004/ ]

(See also that article on how the competing cloud-seeding model cannot be excluded either.)

So such results seems consistent with the science edge.
Surveillance_Egg_Unit
3 / 5 (4) Oct 04, 2018
My opinion is that the research vividly displays that the sparsity of material in the earliest phase of the observed proto-planetary disks.


Your opinion(--)

"A relatively new, well-liked theory called pebble accretion offers a way. In this theory, many tiny pebbles and dust grains quickly glom on to larger objects, suggesting planets can grow faster when they grow by small degrees. Batygin said much of planetary formation research is headed in this direction, and Manara's new study points the same way."

[ https://www.quant...0181004/ ]

(See also that article on how the competing cloud-seeding model cannot be excluded either.)

So such results seems consistent with the science edge.
says tbgl

The link is informative, but I have an entirely different opinion on the origin of planets in the Solar System.
Surveillance_Egg_Unit
2.3 / 5 (6) Oct 04, 2018
-contd

-The "pebble accretion" process could very well happen in disks of other regions, but in the Solar System I would say that there is a high possibility that at least most of the planets came from another Star system not too far distant from the present SS. The Star went supernova and, in the process the explosion caused all of its planets to be kicked out of their orbits and the winds and force of the explosion drove those planets out through the Cosmos toward the region of our present Solar System. As they arrived, their momentum slowed and they floated. As yet, the Sun hadn't accreted from the dust/gas. But when the accretion began, the birth of the Sun was imminent, and finally it ignited its Hydrogen and began the Fusion process.
The planets were already there and, as the Sun began to evolve and Fusion took place, the planets were captured and orbited the Sun.
This, I feel, is the history of the Solar System. Planets coming from another Star that exploded.
Surveillance_Egg_Unit
2.3 / 5 (6) Oct 04, 2018
@tbgl
And, IIRC the dust and gas in the disk of the Solar System went entirely in the creating of the Sun, and there is not much dust left in the Solar System that could be usable to make newer planets possible. And much of the Hydrogen gas is locked up in planets Jupiter and Saturn.
It was a kind of recycling of Matter from elsewhere, that Matter which was still viable and had not disintegrated as it traveled through Space. (Perhaps disintegrate is the wrong term for it).

Your opinion, please.
Surveillance_Egg_Unit
2.3 / 5 (6) Oct 05, 2018
-contd-
In my opinion, each time that there is an explosion of a supernova, any planets that had orbited that Star are kicked out and travel some distance to either be captured and join with preexisting planets and their Star - or the planets who survived the explosion become incorporated within a new, pristine region with its own disk. The disk material may help to prevent planets from colliding, but that would have to be ascertained somewhere in the future.
cantdrive85
3 / 5 (2) Oct 05, 2018
Nobody suggest this is evidence of electrochemistry, jonesdumb will have a heart attack.
rrwillsj
1 / 5 (2) Oct 05, 2018
segue, the problem I see with your theory of interplanetary catch-as-one-can? The velocity imparted to a planet ejected by a supernova would have to be "ludicrous speed" to successfully get away. And not eventually be dragged back into the remnant star system of it's original star system.

At such velocity, how could any star of lesser mass ever hope to capture such a runaway locomotive "high-ballin' to hell!"

That is why I suggested a small but heavy-duty planetoid. That ran into Neptune, explaining what happened to that poor victim of a stellar DUI. The planetoid would need to be massive to survive the collision and still retain enough mass to influence the trans-plutonian worldlets to this day. While losing enough velocity for it to be captured in an outer system orbit. I call this my Theory of Interstellar Billiards.

cant, don't worry, only the crazy ignorant would suggest such nonsense.
rrwillsj
1 / 5 (1) Oct 05, 2018
t_b_g_l, as I am a "believer" in the chaotic universe. Afflicted with stochastic random brewups and cursed by Stupid Design.

That my opinion of the data is that there is no real orderly process to the formation of individual stars and planets. What we claim as Cosmic Rules and Regulations are at best temporary and local. And that Time, whatever the fuck that might be, is truly the missing ingredient to all our hopes and wishes.

I do not expect people to be comfortable with my viewpoint. Complacency erodes the will to strive and evolve. Cows contently chewing their cud is not the future. I'm betting it'll be a race between rattus and merkats.
Surveillance_Egg_Unit
3 / 5 (4) Oct 05, 2018
FYI and FTWAI - Senator Susan Collins is about to yay or nay to the confirmation of Judge Brett Kavanaugh to the Supreme Court of the US. Listening carefully.
Surveillance_Egg_Unit
3 / 5 (4) Oct 05, 2018
OK Senator Collins will confirm Judge Kavanaugh as Supreme Court Justice tomorrow.
To those uninterested in US judicial confirmation processes/politics, I apologise for this off-topic comment. Watch for at least half of all voting-age Americans to go nuts over it with possible violent consequences.

There is no such thing as a "chaotic Universe". While there ARE collisions between Stars and other Stars; and planetary bodies, there is plenty of Space/distance between most of them to move and maneuver within their individual systems/regions.

Planetary bodies have already been hypothesised previously to escape the orbit around their Star of origin and to wander aimlessly into the Cosmos. Therefore, it would not be inconceivable for several planets to have escaped their orbits around a Star that had exploded as supernova and survived to wander into the vicinity of our Solar System's proto-disk.

That would explain how the SS disk has been swept clean of planet-making dust
Surveillance_Egg_Unit
3 / 5 (4) Oct 05, 2018
-contd-
The velocity at which such orphaned planets travel across the Cosmos to wander for a time, is irrelevant, as they have to slow down eventually - although planets of large enough Mass have their own gravity, being able to negate any pull-back gravitational drag from their former burnt-out Star parent.

Such a process whereby planetary objects are shot out of their own orbits when their parent Star explodes, and who wander off to settle down into a region, whether or not that region already has been impacted by a nice, pristine Star of its own. is a very positive process that allows for renewables. Such a renewing of older Mass is, in many cases, done through mechanical processes, such as subduction of tectonic plates.

I visualise this process as being a part of the normal, Natural Order of the Engine of the Universe, as Nature abhors wastefulness.
This process recycles and/or provides a new home for planetary objects that are still viable and reusable.
Surveillance_Egg_Unit
3 / 5 (4) Oct 05, 2018
One of my American housemates is of the opinion that the process is comparable to shopping for Antiques. If it is in very condition, it is still usable. If not, don't buy it.
Surveillance_Egg_Unit
2.3 / 5 (3) Oct 05, 2018
Saturn and Jupiter are failed Stars, as has been said before by me, Benni and granville, IIRC. Their sizes and atmospheric Hydrogen content would serve to explain why they are so distant from the Sun with longer orbits - amongst other factors.
It is possible that those planetary bodies had also escaped the exploding parent Star and wandered into the vicinity of the Solar System long after the inner planets had arrived.
FredJose
1 / 5 (1) Oct 16, 2018
According to Cravens, the higher-than-expected rate of material being expelled from Saturn's D Ring into the planet's upper atmosphere, or ionosphere, is sufficient that astronomers now think the lifespan of the ring may be briefer than previously estimated.

So obviously the rings are not billions of years old as previously thought and emphasized.
Which means they must have arrived later after the planet had existed for some time already.

Or it could also mean that the planet itself is not billions of years old.

Now in case you don't like that last line, just remember that according to the standard nebular theory itself, simulations indicate that the formation of Jupiter and Saturn would take so long that neither should not exist today....!

Whatever option one picks, the rings are a really big problem for the standard model of planetary formation. Now they have to find a mechanism thru which the rings can spring up from the surface via some kind of magic....!
FredJose
1 / 5 (1) Oct 16, 2018
@Surveillance_E_U:
Saturn and Jupiter are failed Stars

I assume you have observational evidence to back this up because here you are stating this as FACT, not just another speculation.
Just because standard theory cannot explain the existence of these planets does not relieve the theorists of the task to explain how they got there naturalistically. Saying they are failed suns simply means that now a new theory (well, evolutionary story really) has to be invented to account for their failure to ignite.

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