The surprising chemical complexity of the rings of Saturn changes the atmosphere of the planet

Well, there is no luggage. But a new study published in Science Based on data from NASA's latest Cassini probe orbits last year, it shows that the rings of Saturn – some of the most visually fabulous objects in the universe – are much more complex on the plane. than what had been understood before.

In addition, the paper shows that the most internal D-ring of the gas giant throws dust grains coated with its chemical cocktail into the upper atmosphere of the planet at an extraordinary speed during its rotation. The researchers explain that over long periods, this infesting material can alter the carbon and oxygen content of the atmosphere.

"This is a new element of the functioning of our solar system," said Thomas Cravens, professor of physics and astronomy at the University of Kansas and co-author of the new article. "Two things surprised me – the first is the chemical complexity of what came out of the rings – we thought it would be almost entirely water, as we have seen in the past." The second thing, it's the quantity of it – much more than we originally expected.The quality and quantity of the materials that the rings put in the atmosphere m & # 39; have surprised. "

Cravens is part of Cassini's IMSI team. At the Cassini "Grande Finale" in 2017, the on-board probe mass spectrometer sampled chemicals at an altitude between Saturn's rings and the atmosphere.

More than water, INMS found that the rings were composed of water, methane, ammonia, carbon monoxide, molecular nitrogen, and carbon dioxide.

"What the paper describes is the environment in the gap between the inner ring and the upper atmosphere, and some of the things found were expected, such as water," Cravens said. "What was a surprise, is that the mass spectrometer saw the methane – no one expected it.He also saw carbon dioxide, which was unexpected.It was thought that the rings were entirely made up of water, but the innermost rings are quite contaminated, with organic matter trapped in ice. "

Another new discovery of the Cassini Mass Spectrometer has shown that a large amount of the chemical substance brewed by Saturn's Ring D is projected into the upper atmosphere of the planet as it spins faster than the atmosphere of the planet itself.

"We saw that this was happening even though it is not yet fully understood," said the KU researcher. "What we saw was that this product, including benzine, was altering the highest atmosphere of Saturn in the equatorial region, and there were contaminated grains and dust."

Cravens said the findings could shed new light on the mechanisms that underpin our solar system as well as other solar systems and exoplanets – and also spark many new scientific questions.

"It could help us understand how a planet gets rings, some do it, some do not," he said. "What is the lifespan of a ring? And what serves to restore the rings? Was there a time when Saturn did not have any rings? How did this composition take place? Has it been introduced there, is there still any formation of our solar system, it goes back to the pre-solar proto nebula, the nebula that has collapsed in an interstellar medium? who formed the sun and the planets? "

According to Cravens, the higher than expected rate of materials expelled from Saturn's D ring in the planet's upper atmosphere, or ionosphere, is enough for astronomers to now think that the lifespan of the planet's satellites is higher. ring could be shorter than previously estimated.

"Thanks to these data, we have now shortened the life of the inner rings because of the amount of material being extracted – which is much more than we previously thought," Cravens said. We know that this eliminates the material of the rings at least 10 times faster than expected. If it's not replenished, the rings will not last – you have a hole in your bucket. Jupiter probably had a ring that evolved to become the current ring, and this could be for similar reasons. The rings come and go. At some point, they dribble gradually unless they get new material. "

With the help of graduate and undergraduate students from the KU, Cravens began by sorting and cleaning the raw data from the Cassini INMS instrument.

"The raw data was transmitted by our Cassini instrument to deep space antennas at 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 declared.

But Cravens' main contribution has been to interpret these data by focusing on how ring materials modify the Saturn ionosphere. Cravens and colleagues report that the influx of chemicals from the rings alters Saturn's equatorial ionospheric chemistry by converting hydrogen ions and triatomic hydrogen ions into heavier molecular ions, reducing the planet's ionospheric density.

"My interest was in the ionosphere, the environment of charged particles, and that's what I focused on," Cravens said. "This waste is entering the ionosphere, affecting its composition and having observable effects, that's what we're trying to understand, the data is clear, but the explanations are still being modeled and it will take some time." Materials arrive at Saturn at high speed because the rings move much faster than the atmosphere, they do not sink gently, but enter as a satellite that enters our own planet. the energy deposition that can dissociate the atmosphere.By atom, it is a rather energetic material because of the difference in velocity between the rings and the atmosphere.We think that it may warm the upper atmosphere and in change the composition. "

Explore further:
Image: The rings on the back of Saturn

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