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In the eyes of distant Earthling, the gap between Saturn and its rings seems calm, like a deep breath of empty space between a beautiful and complex structure. But in 11 new articles, which came about after the disappearance of one of NASA's most valued missions in the field of planetary science, scientists are destroying this illusion by presenting a set of unexpected and complex phenomena dancing to through this void.
These articles, published today in two major scientific journals, represent the first research to publish data from the "Grand Finale" of the Cassini mission, a set of daring orbits in which the probe sinks between Saturn and his rings. Taken together, the newspapers describe in detail what is happening between the deepest rings on the planet and the upper atmosphere. Surprising and catchy phenomena, such as a hail of compounds hammering the equatorial region of the planet and an electric current produced only by the winds and winds of the magnetic field planet.
"We really thought of this as a void," Linda Spilker, NASA's Cassini mission project scientist, told Space Space.com about the area between Saturn and its rings. The team was optimistic about what Cassini could learn when she disappeared, but the operation finally resulted in what she called "a much richer scientific return than we had imagined" – she went to 'to compare it to a brand new mission. [Amazing Saturn Photos from NASA’s Cassini Orbiter]
The Cassini spacecraft spent 13 years studying Saturn and its moons. But when it came to running out of fuel, the mission's scientists devised a bold trajectory that would make the spacecraft loop through Saturn's rings before burning in its atmosphere. This destruction prevented the potentially habitable moons of the system from catching the Earth's germs that may have clung to the spacecraft.
But it also allowed scientists to extract a little more data from his instruments and pushed the spacecraft further than they thought possible, since neither Cassini nor his instruments were designed to accomplish such an incredible feat. The scientists gathered for the first dive, wondering if the spacecraft would survive long enough to even begin the grand finale.
Spilker and other Saturn scientists believe that the revelations of the probe extracted from the data are far from complete, even after the documents published today (4 October). "You're basically looking at the sources of data that Cassini has come to us over the last 13 years. In fact, we have spared only the upper half of the dataset, "said Spilker. This work helped scientists begin to understand the individual phenomena taking place at Saturn. "The next step that is still happening now is to take these elements and bring them together in a coherent picture to examine all the data sets and ask, is there a common history," Spilker said.
But in the meantime, here's a glimpse of what scientists have already learned about the ring planet.
It's raining, it's raining
A new discovery was brought about by the results of such strange instruments that scientists in the team and beyond initially thought there must be a mistake. This instrument, called the ion and neutral mass spectrometer, or INMS, can detect the chemical composition of the captured material.
Scientists are particularly excited to see these results because it had been learned that the instrument was on something. "Since the end of the mission, we have talked a lot about the results of INMS," said Bonnie Meinke, a scientist with the Space Telescope Science Institute (Saturn), who did not participate in any of the new research. "At first glance, that's the kind of thing you almost do not believe in, and as a scientist you have to do a little checking," Meinke said.
The instrument had proven itself, having collected critical data earlier in the mission while Cassini was exploring moons such as Titan and Enceladus. "Then we really have to focus on Saturn and let it play the star role for the last part of the mission," said Rebecca Perryman, operations manager for INMS at the Southwest Research Institute at Space.com. "We did everything we could to get everything planned and we bragged that INMS would be able to get fantastic results once we started diving into the atmosphere." [In Photos: Cassini Mission Ends with Epic Dive into Saturn]
They expected these results to measure the masses of "circular rain," which scientists saw as a trickle of tiny particles falling from the inner circle of Saturn to the planet's upper atmosphere – hydrogen and Helium for the most part – nothing extraordinary.
But what they seem to have found was much larger than expected, coming from much more exotic compounds. The instrument spotted not only hydrogen and helium, but also carbon monoxide, methane, nitrogen and unidentifiable remains of organic molecules.
Other instruments suggested that this downpour also included ice-water and silicate particles and showed that the shower was triggered by the interaction of these particles with the highest levels of Saturn's atmosphere. Around the ring structure, this amounts to about 10 tons (9,000 kilograms) per second.
"The complexity of what was going on there and the amount of material collected was very surprising," said Hunter Waite, lead INMS investigator and scientist at the Southwest Research Institute, on Space.com. And the discovery does not just reveal an intriguing phenomenon in a distant world – scientists say that if the results are valid, the consequences could be much deeper for our solar system and beyond.
Waite said the unexpected diversity of compounds in the ring rain could affect estimates of the composition of the atmosphere by scientists, which would eventually involve adapting assumptions about the formation and the evolution of Saturn and its neighbors. "This facade may only have that facade," Waite said of Saturn. "[That might have] been a little misleading in the direction of our thinking about training and evolution. "
In addition, because there is so much material, the new results are a puzzle: where does it come from? "It can not be a continuous process, otherwise the rings would not be there," Meinke said. They would lack material in maybe tens of thousands of years, leaving Saturn in the shelter. [the paper is] to tell is the turn of the rings of Saturn … The rings can be alive because they move and turn constantly.
The magnetic call of a planet
Cassini was also equipped to measure the magnetic field of Saturn. Although scientists have already studied the magnetic field, they were able to do so only briefly on overflights like those of Pioneer and Voyager, and the Cassini Grand Final plunged them deeper than ever into this field.
And the measurements gathered during these tight curls offered their own surprises. Scientists already knew that the magnetic field of Saturn seemed to align perfectly with the axis on which it turns, which is a challenge, because, as far as we can understand, the magnetic fields are by definition created by crossing the spins. [Cassini’s Greatest Hits: The Spacecraft’s Best Images of Saturn]
But a new analysis of the measurements of the grand finale shows that these two phenomena align even more perfectly than the scientists had predicted. This means that scientists must return to the board, trying to convince a response from gravity data and magnetic fields. "We know there's something weird about," Michele Dougherty, a physicist at Imperial College London, told Space.com.
She and her colleagues think that there may be something that blocks the scientists' view of Saturn's true magnetic heart, creating the illusion of almost perfect alignment and thwarting their theories. "We do not have the answer yet, but whatever response is proposed, it will actually change people's understanding of the inner structure of planets," Dougherty said.
As long as they do not understand what is happening, scientists will not be able to accurately measure the time it takes for Saturn to turn. "It's a little awkward, we've been in orbit for 13 years and we still can not tell how much time is left in Saturn," Dougherty said. Without fixed characteristics on a solid surface or magnetic field to follow, they are blocked with an estimate of 10.7 hours.
Hunting in the heart of the magnetic field was partially blurred by another surprise hidden in the magnetic data: a new phenomenon produced by this magnetic field interacting with bands of winds moving at different speeds in the upper atmosphere of Saturn: a current electric waving through a layer of atmosphere called the thermosphere.
Here's how it works: Saturn is wrapped in wind bands, with the equator being the fastest and the north and south slower. When a loop-shaped magnetic field structure aligns so that one end lies in this equatorial band and the other one does not, the equatorial wind pulls the charged plasma particles that surround it, which in turn directs the magnetic field line.
The result measured by Cassini is an electric current as powerful as 20 large combined terrestrial power plants. As a side effect, this current also produces heat in the surrounding atmosphere, which can help explain a long-standing mystery about Saturn. "One of the enigmas of Saturn's thermosphere is that it's hotter than expected," Krishan Khurana, a magnetosphere scientist at the University of California at Los Angeles, told Space Space.com. . "That provides part of the answer."
And while Saturn is the star here, the results can also explain a second mystery of the solar system. "Jupiter's atmosphere is very turbulent and the same phenomenon applied to Jupiter's magnetic field would create quite large currents and warm up the thermosphere quite quickly," said Khurana. This includes the big red spot, the giant storm that infamous Jupiter's southern hemisphere, and which scientists had realized was terribly roasted. [Wave at Saturn: Images from NASA’s Cosmic Photo Bomb by Cassini Probe]
The grand finale is not the end
It's just a sample of the research published today, which is really just the beginning of the scientific flow that the Cassini Finale will eventually produce. A paper has been devoted to Saturn's atmosphere, which produces radio auroral emissions to try to understand how these radio waves are produced.
In another article, a team of researchers identified a long-awaited but unknown radiation belt that extends from the planet's upper atmosphere to its innermost ring. This means that it is completely separate from the main magnetosphere of Saturn, retaining the charged particles in this space between the upper atmosphere and the inner ring. Further study of this new radiation belt shows that because of the interference of large rings, this radiation belt is quite weak compared to other structures of this type.
A different instrument aboard Cassini measured the electron density in the Saturn ionosphere, mapping two separate layers. The lower layer includes larger, neutral molecules and charged around the equator, under the rings and their flow of material; the upper layer has a much smaller number of tiny charged particles.
And this same INMS instrument, which made it possible to identify as many strange compounds in the so-called annular rain, also allowed scientists to calculate the approximate temperatures of the thermosphere layer of the atmosphere traversed by Cassini. These measurements ranged from 67 to 97 degrees Celsius (150 to 200 degrees Fahrenheit).
Two other articles that were not yet ready for publication dealt with subjects such as the tiny moons encrusted in the rings of Saturn and the gravity measurements taken on the giant planet. And then, of course, there are many more discoveries to be made as scientists continue to delve into and analyze the data from the Grand Final and the rest of Cassini's work – not to mention the sightings of any successor spacecraft inspired by the discoveries of the mission.
"I think it's a really exciting time," said Meinke, the Saturn scientist who is not affiliated with any new research. "After 13 years of Cassini data, this last little bit was really the most exciting, which made us want to go back and really taught us a lot more than we expected to learn."
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