"Кассини" !

Автор sol, 28.01.2004 19:13:59

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Chilik

^^
может быть, они молекулы по типам считают, не смотря на концентрацию.
Типа: 
водород есть - ставим плюсик.
метанол есть - ставим плюсик.
РВ есть - ставим три плюсика.
 :o

tnt22

https://saturn.jpl.nasa.gov/resources/7801/
ЦитироватьHalf-lit Dione



Photojournal: PIA21349

October 12, 2017

Saturn's moon Dione is captured in this view from NASA's Cassini spacecraft, half in shadow and half in light. Sinuous canyons carve interconnected paths across the moon's icy landscape.  Subtle variations in brightness hint at differences in composition, as well as the size and shape of grains in Dione's surface material, or regolith.
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Cassini spent more than a decade at Saturn studying Dione (698 miles or 1,123 kilometers across) and the planet's many other moons as part of the quest to understand how the moons formed and evolved, and how they are connected.

This view looks toward the side of Dione that faces away from Saturn. North is up and rotated 31 degrees to the left. The image was taken in visible light with the Cassini spacecraft narrow-angle camera on June 22, 2017.

The view was obtained at a distance of approximately 224,000 miles (360,000 kilometers) from Dione. Image scale is 1.4 mile (2.2 kilometers) per pixel.

The Cassini spacecraft ended its mission on Sept. 15, 2017.

The Cassini mission is a cooperative project of NASA, ESA (the European Space Agency) and the Italian Space Agency. The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the mission for NASA's Science Mission Directorate, Washington. The Cassini orbiter and its two onboard cameras were designed, developed and assembled at JPL. The imaging operations center is based at the Space Science Institute in Boulder, Colorado.

For more information about the Cassini-Huygens mission visit https://saturn.jpl.nasa.gov and https://www.nasa.gov/cassini. The Cassini imaging team homepage is at http://ciclops.org.

Credit

NASA/JPL-Caltech/Space Science Institute

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tnt22

https://www.jpl.nasa.gov/news/news.php?feature=6976
ЦитироватьOctober 16, 2017

Fresh Findings From Cassini
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Saturn looms in the foreground of this mosaic of Cassini images, taken by the spacecraft on May 28, 2017. Image credit: NASA/JPL-Caltech/Space Science Institute
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Cassini obtained this panoramic view of Saturn's rings on Sept. 9, 2017, just minutes after it passed through the ring plane. Image credit: NASA/JPL-Caltech/Space Science Institute
› Full image and caption


Cassini used its Ultraviolet Imaging Spectrograph to capture this final view of ultraviolet auroral emissions in Saturn's north polar region on Sept. 14, 2017. Image credit: NASA/JPL/Univ. Colorado/Univ. Liege-LPAP
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NASA's Cassini spacecraft ended its journey on Sept. 15 with an intentional plunge into the atmosphere of Saturn, but analysis continues on the mountain of data the spacecraft sent during its long life. Some of the Cassini team's freshest insights were presented during a news conference today at the American Astronomical Society Division for Planetary Science meeting in Provo, Utah.

Among the findings being shared:
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-- Views from Cassini's Grand Finale show the beauty of the rings and demonstrate processes similar to those that form planets.

During Cassini's final months, the spacecraft's cameras captured views from within the gap between the planet and the rings, and the mission is releasing two new image mosaics showing the rings from that unique perspective. One view, from May 28, 2017, shows the rings emerging from behind the planet's hazy limb, while the planet itself is adorned with ring shadows. The other mosaic shows a panoramic view outward across the ringscape.

Researchers also shared a new movie of Saturn's auroras in ultraviolet light that represents the final such view from the spacecraft's Ultraviolet Imaging Spectrometer.

In addition, Cassini participating scientist and imaging team associate Matt Tiscareno of SETI Institute, Mountain View, California, provided new details about the whimsically named ring features called propellers, which are wakes in the rings created by small, unseen moonlets. The propellers are analogous to baby planets forming in disks around young stars, as they obey similar physical processes.

Tiscareno said that, in its last images of the rings (taken the day before the spacecraft's plunge into Saturn), Cassini successfully imaged all six of the propellers whose orbits were being tracked over the last several years of the mission. These objects are named for famous aviators: Blériot, Earhart, Santos-Dumont, Sikorsky, Post and Quimby. During its Ring-Grazing Orbits -- the four months of close orbits that preceeded the mission's Grand Finale -- Cassini obtained images showing swarms of smaller propellers, astounding Tiscareno and colleagues.

-- Cassini's electronic "nose" hit the jackpot, finding many surprises as it sniffed the gases in the previously unexplored space between the planet and the rings.

The spacecraft's Ion and Neutral Mass Spectrometer (INMS) returned a host of first-ever direct measurements of the components in Saturn's upper atmosphere, which stretches almost to the rings. From these observations, the team sees evidence that molecules from the rings are raining down onto the atmosphere. This influx of material from the rings was expected, but INMS data show hints of ingredients more complex than just water, which makes up the bulk of the rings' composition. In particular, the instrument detected methane, a volatile molecule that scientists would not expect to be abundant in the rings or found so high in Saturn's atmosphere. Cassini participating scientist and INMS team associate Mark Perry from the Johns Hopkins University Applied Physics Laboratory, Laurel, Maryland, says the team is busy analyzing data from the final, lowest-altitude passes, which show even more complexity and variability. The INMS observations complement those by Cassini's Cosmic Dust Analyzer instrument, which sampled solid particles in the gap during the Grand Finale.

-- Researchers continue trying to wrangle insights about the length of the planet's day from measurements of Saturn's magnetic field.

Michele Dougherty, leader of Cassini's Magnetometer team from Imperial College London, provided an update on the team's progress in trying to determine whether Saturn's magnetic field has a detectable tilt. One aim of their work is to determine the precise length of time for the planet's internal rotation, which would help researchers nail down the true length of the planet's day. Dougherty says the sensitivity of Cassini's magnetic field measurements nearly quadrupled over the course of the spacecraft's 22 Grand Finale orbits -- meaning that, if the tilt of Saturn's field is greater than 0.016 degrees, researchers should be able to detect it. An extremely small tilt is challenging to explain with scientists' current understanding of how planetary magnetic fields are generated, thus suggesting more sophisticated dynamics inside Saturn.

-- New theoretical research explains the forces that keep Saturn's rings from spreading out and dispersing. It turns out to be a group effort.

Key among the questions scientists hope to answer using data from Cassini are the age and origins of the rings. Theoretical modeling has shown that, without forces to confine them, the rings would spread out over hundreds of millions of years -- much younger than Saturn itself. This spreading happens because faster-moving particles that orbit closer to Saturn occasionally collide with slower particles on slightly farther-out orbits. When this happens, some momentum from the faster particles is transferred to the slower particles, speeding the latter up in their orbit and causing them to move farther outward. The inverse happens to the faster, inner particles.

Previous research had shown that gravitational tugs from the moon Mimas are solely responsible for halting the outward spread of Saturn's B ring -- that ring's outer edge is defined by the dark region known as the Cassini Division. Ring scientists had thought the small moon Janus was responsible for confining the outer edge of the A ring. But a new modeling study led by Radwan Tajeddine of Cornell University, Ithaca, New York, shows that the A ring's outward creep is kept in check by a confederation of moons, including Pan, Atlas, Prometheus, Pandora, Janus, Epimetheus and Mimas.

The insight was made possible by Cassini, which provided scientists with high-resolution views of intricate waves in the rings, along with precise determinations of the masses of Saturn's moons. Analysis of these data led Tajeddine and colleagues to an understanding that a cumulative effect of waves from all these moons damps the outward transfer of momentum in the A ring and confines its edge.

Tajeddine will present these results in a poster at the DPS meeting, and they will be published Wednesday in the Astrophysical Journal.

"There are whole careers to be forged in the analysis of data from Cassini," said Linda Spilker, the mission's project scientist at NASA's Jet Propulsion Laboratory, Pasadena, California. "In a sense, the work has only just begun."

The Cassini-Huygens mission is a cooperative project of NASA, ESA (European Space Agency) and the Italian Space Agency. NASA's Jet Propulsion Laboratory, a division of Caltech in Pasadena, manages the mission for NASA's Science Mission Directorate, Washington. JPL designed, developed and assembled the Cassini orbiter.

More information about Cassini:

https://www.nasa.gov/cassini

https://saturn.jpl.nasa.gov

News Media Contact

Preston Dyches
 Jet Propulsion Laboratory, Pasadena, Calif.
 818-354-7013
 preston.dyches@jpl.nasa.gov

 2017-271
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tnt22

https://www.nasa.gov/feature/goddard/2017/nasa-team-finds-noxious-ice-cloud-on-saturns-moon-titan
ЦитироватьOct. 18, 2017

NASA Team Finds Noxious Ice Cloud on Saturn's Moon Titan

Researchers with NASA's Cassini mission found evidence of a toxic hybrid ice in a wispy cloud high above the south pole of Saturn's largest moon, Titan.

The finding is a new demonstration of the complex chemistry occurring in Titan's atmosphere—in this case, cloud formation in the giant moon's stratosphere—and part of a collection of processes that ultimately helps deliver a smorgasbord of organic molecules to Titan's surface.
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This view of Saturn's largest moon, Titan, is among the last images the Cassini spacecraft sent to Earth before it plunged into the giant planet's atmosphere.
Credits: NASA/JPL-Caltech/Space Science Institute

Invisible to the human eye, the cloud was detected at infrared wavelengths by the Composite Infrared Spectrometer, or CIRS, on the Cassini spacecraft. Located at an altitude of about 100 to 130 miles (160 to 210 kilometers), the cloud is far above the methane rain clouds of Titan's troposphere, or lowest region of the atmosphere. The new cloud covers a large area near the south pole, fr om about 75 to 85 degrees south latitude.

Laboratory experiments were used to find a chemical mixture that matched the cloud's spectral signature -- the chemical fingerprint measured by the CIRS instrument. The experiments determined that the exotic ice in the cloud is a combination of the simple organic molecule hydrogen cyanide together with the large ring-shaped chemical benzene. The two chemicals appear to have condensed at the same time to form ice particles, rather than one being layered on top of the other.

"This cloud represents a new chemical formula of ice in Titan's atmosphere," said Carrie Anderson of NASA's Goddard Space Flight Center in Greenbelt, Maryland, a CIRS co-investigator. "What's interesting is that this noxious ice is made of two molecules that condensed together out of a rich mixture of gases at the south pole."

Previously, CIRS data helped identify hydrogen cyanide ice in clouds over Titan's south pole, as well as other toxic chemicals in the moon's stratosphere.

In Titan's stratosphere, a global circulation pattern sends a current of warm gases fr om the hemisphere wh ere it's summer to the winter pole. This circulation reverses direction when the seasons change, leading to a buildup of clouds at whichever pole is experiencing winter. Shortly after its arrival at Saturn, Cassini found evidence of this phenomenon at Titan's north pole. Later, near the end of the spacecraft's 13 years in the Saturn system, a similar cloud buildup was spotted at the south pole.

The simple way to think about the cloud structure is that different types of gas will condense into ice clouds at different altitudes, almost like layers in a parfait dessert. Exactly which cloud condenses wh ere depends on how much vapor is present and on the temperatures, which become colder and colder at lower altitudes in the stratosphere. The reality is more complicated, however, because each type of cloud forms over a range of altitudes, so it's possible for some ices to condense simultaneously, or co-condense.

Anderson and colleagues use CIRS to sort through the complex set of infrared fingerprints from many molecules in Titan's atmosphere. The instrument separates infrared light into its component colors, like raindrops creating a rainbow, and measures the strengths of the signal at the different wavelengths.

"CIRS acts as a remote-sensing thermometer and as a chemical probe, picking out the heat radiation emitted by individual gases in an atmosphere," said F. Michael Flasar, the CIRS principal investigator at Goddard. "And the instrument does it all remotely, while passing by a planet or moon."

The new cloud, which the researchers call the high-altitude south polar cloud, has a distinctive and very strong chemical signature that showed up in three sets of Titan observations taken from July to November 2015. Because Titan's seasons last seven Earth years, it was late fall at the south pole the whole time.

The spectral signatures of the ices did not match those of any individual chemical, so the team began laboratory experiments to simultaneously condense mixtures of gases. Using an ice chamber that simulates conditions in Titan's stratosphere, they tested pairs of chemicals that had infrared fingerprints in the right part of the spectrum.

At first, they let one gas condense before the other. But the best result was achieved by introducing both hydrogen cyanide and benzene into the chamber and allowing them to condense at the same time. By itself, benzene doesn't have a distinctive far-infrared fingerprint. When it was allowed to co-condense with hydrogen cyanide, however, the far-infrared fingerprint of the co-condensed ice was a close match for the CIRS observations.

Additional studies will be needed to determine the structure of the co-condensed ice particles. The researchers expect them to be lumpy and disorderly, rather than well-defined crystals.

Anderson and colleagues previously found a similar example of co-condensed ice in CIRS data from 2005. Those observations were made near the north pole, about two years after the winter solstice in Titan's northern hemisphere. That cloud formed at a much lower altitude, below 93 miles (150 kilometers), and had a different chemical composition: hydrogen cyanide and cyanoacetylene, one of the more complex organic molecules found in Titan's atmosphere.

Anderson attributes the differences in the two clouds to seasonal variations at the north and south poles. The northern cloud was spotted about two years after the northern winter solstice, but the southern cloud was spotted about two years before the southern winter solstice. It's possible that the mixtures of gases were slightly different in the two cases or that temperatures had warmed up a bit by the time the north polar cloud was spotted, or both.

"One of the advantages of Cassini was that we were able to flyby Titan again and again over the course of the thirteen-year mission to see changes over time," said Anderson. "This is a big part of the value of a long-term mission."

The Cassini spacecraft ended its Saturn mission on Sept. 15, 2017.

The Cassini-Huygens mission is a cooperative project of NASA, ESA (European Space Agency) and the Italian Space Agency. NASA's Jet Propulsion Laboratory, a division of Caltech in Pasadena, manages the mission for NASA's Science Mission Directorate, Washington. JPL designed, developed and assembled the Cassini orbiter.

More information about Cassini:

https://www.nasa.gov/cassini

https://saturn.jpl.nasa.gov
 

Elizabeth Zubritsky
NASA's Goddard Space Flight Center in Greenbelt, Md.
 301-614-5438
elizabeth.a.zubritsky@nasa.gov
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Last Updated: Oct. 18, 2017
Editor: Karl Hille

tnt22

https://spaceflightnow.com/2017/10/19/cassini-results-still-keeping-scientists-busy/
ЦитироватьCassini results still keeping scientists busy
October 19, 2017 Stephen Clark

Scientists examining data fr om the Cassini mission's final months reported this week unexpected measurements of Saturn's gravity field and outer atmosphere, suggesting they may have to revisit theories about the planet's rings and the forces that generate magnetic fields.
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Cassini took this image of Saturn in April 2016 from a distance of approximately 1.9 million miles (3 million kilometers). Credit: NASA/JPL-Caltech/Space Science Institute

Presenting an update at the American Astronomical Society's Division for Planetary Sciences meeting in Provo, Utah, researchers said Monday that NASA's Cassini spacecraft yielded unforeseen results as it repeatedly looped between Saturn and its rings during the final four months of the nearly 20-year mission.

"We've been analyzing the grand finale data, and there are lots of surprises," said Linda Spilker, Cassini's project scientist at NASA's Jet Propulsion Laboratory. "Saturn, its rings, and the region in between are not what we expected."

Thirteen years since it braked into orbit around Saturn, Cassini made 22 passes through the gap between planet and its rings between late April and Sept. 15. Ground controllers intentionally guided the plutonium-powered probe toward a destructive dive into the planet's hydrogen atmosphere last month.

Scientists devised Cassini's final act to collect new measurements of Saturn's atmosphere, and gather data on the planet's gravity and magnetic fields, which they expected to provide insights about the inner structure of Saturn, including the size and nature of its core.

Michele Dougherty, a researcher from Imperial College London, said Cassini's instruments helped refine estimates of the tilt of Saturn's magnetic field, revealing it to be closely aligned with the planet's rotation axis.

"The real surprise is turning out to be the fact that the tilt between the rotation axis of the planet and the dipole axis is really small," Dougherty said.

Scientists knew the rotation and magnetic field axes were in tight alignment, predicting before Cassini's newest measurements that they were separated by less than 0.6 degrees. Now they estimate the tilt is less than 0.06 degrees.

Magnetic fields on Earth and Jupiter are produced by dynamos deep inside the planets, wh ere conducting fluid under heavy pressure generates an electric current, helping propagate a field that extends outside the planets' atmospheres, creating a magnetic bubble responsible for producing auroras and shielding from solar and cosmic radiation.


This illustration shows the interior of Saturn, including its core of heavy elements (orange), liquid metallic hydrogen layer (grey), and gaseous molecular hydrogen envelope (brown). The planet's magnetic field is thought to originate from the top of the metallic hydrogen layer. Credit: NASA/JPL-Caltech

Earth's dynamo uses liquid iron to generate its magnetic field. Dynamos inside gas giants like Jupiter and Saturn are believed to rely on hydrogen compressed under the force of several million atmospheres and stripped of their electrons, making it behave like a metal.

Conventional thought on dynamos inside Earth and Jupiter suggest they require a tilt between the rotation and magnetic field axes. Earth's dipole is oriented around 11.5 degrees from its rotation axis, and Jupiter's differs by about 10 degrees.

Mathematical models indicate a planet's magnetic field would wither if the axes were aligned, dying within around 100 million years instead of persisting through the solar system's 4.5-billion-year history.

"The fact that we haven't been able to measure this tilt yet — we know that it's really very small — points to the fact that there's much more sophisticated dynamics taking place inside Saturn than we thought," Dougherty said.

Once they complete their detective work, Dougherty said scientists will have a better idea of the size of Saturn's core, and the source of the magnetic field.

"My understanding is that we're going to change our minds about planetary dynamos," she said.

Cassini's magnetic field measurements during the mission's grand finale orbits were four times more sensitive than before, Dougherty said.

"By getting inside the rings ... we were away from the currents being generated by the rings — currents being generated in the environment around Saturn — (and) it is allowing us to focus on the signal coming from the interior."

The data will also help scientists sort out the rotation rate of planet's interior, telling them the exact length of a day on Saturn. The best estimate today suggests a Saturn day lasts around 10.8 hours.

Cassini's ion and neutral mass spectrometer sampled Saturn's atmosphere as the spacecraft barreled inside the rings. The atmosphere's tenuous outer layers extend out almost to the rings, and Cassini discovered molecules raining down from the rings onto Saturn.


This natural color composite is one of the highest-resolution color images of any part of Saturn's rings, to date, showing a portion of the inner-central part of the planet's B Ring. Cassini's narrow-angle camera took images to produce this composite on July 6, 2017. Credit: NASA/JPL-Caltech/Space Science Institute

Scientists expected to find evidence of ring material in Cassini's first-ever direct measurements of the atmosphere, but the spacecraft detected unexpectedly high levels of methane.

They predicted most of the molecules to be water because that makes up the bulk of the particles in the rings.

Methane should not persist in Saturn's rings or in the planet's outer atmosphere, said Mark Perry, an associate scientist on the ion and neutral mass spectrometer team.

"What we're seeing are things that come from the rings, and methane is highly volatile," Perry said. "Even if it's in the rings, it shouldn't last very long, and none of the models — none of the analyses — predicted methane, let alone in this abundance."

Cassini also found the expected water molecules in the outer atmosphere, but the methane was a surprise.

"We think the water is there," Perry said. "What we can't explain is why it is not much more than anything else. That's the confusing part."

Cassini's narrow-angle imaging camera obtained close-up views of intricate structures inside Saturn's rings during the mission's final months. One new mosaic recorded by Cassini in May shows the rings emerging from behind Saturn's hazy limbs, with the rings' shadows projected on the planet's atmosphere.

Before it zipped through Saturn's ring gap, Cassini was on a trajectory that grazed the outer edge of the rings on each orbit.

The spacecraft took pictures of features dubbed propellers — wakes created by tiny moons that would have otherwise gone undetected. The moonlets embedded inside Saturn's rings leave a distinguishing mark, disturbing nearby particles as they sail around the planet.

"These are important because this is a window into planetary formation processes," said Matthew Tiscareno of the SETI Institute. "What happens when big solar systems are forming is that you start to get the seed of a planet, but it's embedded in a disk. So the disk is affecting the embedded mass, but the embedded mass is also affecting the disk, and we want to know more about what happens in both directions, and propellers give us a window into that."


This view from NASA's Cassini spacecraft shows Cassini's best image of the propeller feature known informally as Bleriot. The propeller is named after Louis Bleriot, the French engineer and aviator who in 1909 was the first person to fly across the English Channel. Credit: NASA/JPL-Caltech/Space Science Institute

Tiscareno said scientists identified propellers with two classes of moonlets — some a few hundred meters in size and some around a kilometer (0.6 miles) across.

One primary objective of Cassini's grand finale was to determine the mass, age and origin of Saturn's rings.

Cassini's position close to Saturn in the last few months allowed the probe's instruments to sort out the difference between the pull of gravity from the planet and the rings.

If the rings are more massive, scientists think they could be old, perhaps as old as Saturn itself. A result indicating less massive rings would point to a more recent origin, perhaps when a moon or comet got too close to Saturn and was ripped apart.

The initial results suggest the rings are slightly less massive than expected, Spilker said, but uncertainty remains in the measurements. Scientists still must calculate the strength of Saturn's gravity field from data downlinked from Cassini and remove the effect of atmospheric drag from the measurements.

"Once we resolve Saturn's gravity field, we'll have a better handle then on the mass of the rings," Spilker said.

A new study based on Cassini data shows that the gravitational pull from several of Saturn's moons combine to keep Saturn's rings from spreading out and disappearing.

Scientists thought the small moon Janus single-handedly kept the rings in check, but measurements of the masses of Saturn's moons and detailed images of waves in the rings led to a conclusion that seven moons — Pan, Atlas, Prometheus, Pandora, Janus, Epimetheus and Mimas — work together to keep the outer A ring from extending farther from Saturn.

Radwan Tajeddine of Cornell University led the study investigating the relationship between Saturn's moons and rings.

"If these moons weren't working together, then the A ring would have spread out over hundreds of millions of years, and the A ring would be gone," Spilker said.

Meanwhile, engineers have assessed how the Cassini spacecraft behaved in its final moments plunging into Saturn's atmosphere.


Artist's concept of the Cassini spacecraft entering Saturn's atmosphere. Credit: NASA/JPL-Caltech

Launched 20 years ago this week, Cassini was traveling through the rarefied outer layers of Saturn's atmosphere as it beamed back its last data to Earth, speeding through gas with about the same density that as encountered by the International Space Station as it soars 250 miles (400 kilometers) above Earth, according a NASA press release.

But Cassini was moving four-and-a-half times faster than the space station, multiplying the aerodynamic forces, officials said.

Cassini encountered Saturn's atmosphere as it reached a point around 1,200 miles (3,600 kilometers) above the cloud tops. Atmospheric particles began pushing on Cassini's 36-foot-long (11-meter) magnetometer boom.

The spacecraft fired thrusters to damp its rotation, using its jets for longer and more frequent pulses as it fell deeper into the atmosphere, according to NASA.

"With its thrusters firing almost continuously, the spacecraft held its own for 91 seconds against Saturn's atmosphere — the thrusters reaching 100 percent of their capacity during the last 20 seconds or so before the signal was lost," officials wrote in a press release. "The final eight seconds of data show that Cassini started to slowly tip over backward."

Engineers programmed Cassini to broadcast science data and telemetry in real-time during its final moments, rather than storing the information on recorders for later playback.

Tracking antennas on Earth lost lock with Cassini's dish-shaped antenna as the spacecraft turned away. A radio carrier signal continued streaming down from the probe for 24 more seconds, then it went silent.

"Given that Cassini wasn't designed to fly into a planetary atmosphere, it's remarkable that the spacecraft held on as long as it did, allowing its science instruments to send back data to the last second," said Earl Maize, Cassini project manager at JPL. "It was a solidly built craft, and it did everything we asked of it."
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tnt22

https://www.nasa.gov/image-feature/jpl/pia21352/the-grace-of-saturn
ЦитироватьOct. 23, 2017

The Grace of Saturn



Saturn's graceful lanes of orbiting ice -- its iconic rings -- wind their way around the planet to pass beyond the horizon in this view from NASA's Cassini spacecraft.  And diminutive Pandora, scarcely larger than a pixel here, can be seen orbiting just beyond the F ring in this image.
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Also in this image is the gap between Saturn's cloud tops and its innermost D ring through which Cassini would pass 22 times before ending its mission in spectacular fashion in Sept. 15, 2017.  Scientists scoured images of this region, particularly those taken at the high phase (spacecraft-ring-Sun) angles, looking for material that might pose a hazard to the spacecraft.

This view looks toward the sunlit side of the rings from about 19 degrees above the ringplane. The image was taken in green light with the Cassini spacecraft wide-angle camera on Aug. 12, 2017. Pandora was brightened by a factor of 2 to increase its visibility.

The view was obtained at a distance to Saturn of approximately 581,000 miles (935,000 kilometers) from Saturn. Image scale is 35 miles (56 kilometers) per pixel. The distance to Pandora was 691,000 miles (1.1 million kilometers) for a scale of 41 miles (66 kilometers) per pixel.

The Cassini spacecraft ended its mission on Sept. 15, 2017.

The Cassini mission is a cooperative project of NASA, ESA (the European Space Agency) and the Italian Space Agency. The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the mission for NASA's Science Mission Directorate, Washington. The Cassini orbiter and its two onboard cameras were designed, developed and assembled at JPL. The imaging operations center is based at the Space Science Institute in Boulder, Colorado.

For more information about the Cassini-Huygens mission visit https://saturn.jpl.nasa.gov and https://www.nasa.gov/cassini. The Cassini imaging team homepage is at http://ciclops.org.

Credit: NASA/JPL-Caltech/Space Science Institute
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Last Updated: Oct. 23, 2017
Editor: Tony Greicius

Maks

#2506
меня поразило, что кольцо состоит из огромных скал из льда, размером в километры. Они отбрасывают тень  длинои в сотни км.Тень oT oднoi скалы  лежит на кольце Сатурна.
Я был на горе Конжаковский камень на Урале и видел похожее.Там мы стояли во время восхода солнца на этой горе высотои около 1600 м.Гора отбросила тень. Kогда мы махали руками, то не видели себя.Вдали okolo 40 km виднелась гора Денежкин камень. Она также отбрасывала тень.2 горы мне кажется, похожи пo paзmepam на 2 айсберга-скалы-елемента кольца Сатурна.

tnt22

https://saturn.jpl.nasa.gov/resources/7777/
ЦитироватьThe Saturn System Through the Eyes of Cassini (e-Book)



October 19, 2017

Updated: Oct. 19, 2017

This free NASA e-Book celebrates Saturn as seen through the eyes of the Cassini spacecraft.
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The Cassini-Huygens mission has revolutionized our knowledge of the Saturn system and revealed surprising places in the solar system where life could potentially gain a foothold—bodies we call ocean worlds.

Since its arrival in 2004, Cassini–Huygens has been nothing short of a discovery machine, captivating us with data and images never before obtained with such detail and clarity. Cassini taught us that Saturn is a far cry from a tranquil lone planet with delicate rings. Now, we know more about Saturn's chaotic, active, and powerful rings, and the storms that rage beneath. Images and data from Saturn's moons Titan and Enceladus hint at the possibility of life never before suspected. The rings of Saturn, its moons, and the planet itself offer irresistible and inexhaustible subjects for intense study. As the Cassini mission comes to a dramatic end with a fateful plunge into Saturn on Sept. 15, 2017, scientists are already dreaming of going back for further study.

Over a period of 13 years, Cassini has captured about 450,000 spectacular images within the Saturn system, providing new views of the "lord of the rings" and a plethora of iconic images. To honor the art and science of Cassini, this book was developed collaboratively by a team from NASA's Planetary Science Division (PSD), NASA's Jet Propulsion Laboratory (JPL), and the Lunar and Planetary Institute (LPI). While these images represent the tip of the iceberg—each telling a story about Saturn and its mysterious moons—our hope is that the mission will inspire future artists and explorers. The sheer beauty of these images is surpassed only by the science and discoveries they represent.

This book was developed collaboratively by the National Aeronautics and Space Administration (NASA) including NASA's Planetary Science Division (PSD), NASA's Jet Propulsion Laboratory (JPL), and the Lunar and Planetary Institute (LPI), operated for NASA by Universities Space Research Association.

Credit
NASA / Jet Propulsion Laboratory - Caltech / Lunar and Planetary Institute

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Georgij

На языке вероятного противника, увы не читаю
Всегда готов!

Атяпа

ЦитироватьGeorgij пишет:
На языке вероятного противника, увы не читаю
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https://saturn.jpl.nasa.gov/resources/7806/

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https://www.nasa.gov/image-feature/jpl/pia21351/the-north
ЦитироватьThe North



Photojournal: PIA21351

October 30, 2017

Reflected sunlight is the source of the illumination for visible wavelength images such as the one above.  However, at longer infrared wavelengths, direct thermal emission from objects dominates over reflected sunlight. This enabled instruments that can detect infrared radiation to observe the pole even in the dark days of winter when Cassini first arrived at Saturn and Saturn's northern hemisphere was shrouded in shadow.
Спойлер
Now, 13 years later, the north pole basks in full sunlight. Close to the northern summer solstice, sunlight illuminates the previously dark region, permitting Cassini scientists to study this area with the spacecraft's full suite of imagers.

This view looks toward the northern hemisphere from about 34 degrees above Saturn's ringplane. The image was taken with the Cassini spacecraft wide-angle camera on April 25, 2017 using a spectral filter which preferentially admits wavelengths of near-infrared light centered at 752 nanometers.

The view was acquired at a distance of approximately 274,000 miles (441,000 kilometers) from Saturn and at a Sun-Saturn-spacecraft, or phase, angle of 111 degrees. Image scale is 16 miles (26 kilometers) per pixel.

The Cassini spacecraft ended its mission on Sept. 15, 2017.

The Cassini mission is a cooperative project of NASA, ESA (the European Space Agency) and the Italian Space Agency. The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the mission for NASA's Science Mission Directorate, Washington. The Cassini orbiter and its two onboard cameras were designed, developed and assembled at JPL. The imaging operations center is based at the Space Science Institute in Boulder, Colorado.

For more information about the Cassini-Huygens mission visit https://saturn.jpl.nasa.gov and https://www.nasa.gov/cassini. The Cassini imaging team homepage is at http://ciclops.org.

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NASA/JPL-Caltech/Space Science Institute
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ЦитироватьPandora, the Would-Be Perturber



Photojournal: PIA21355

November 6, 2017

As Cassini hurtled toward its fatal encounter with Saturn, the spacecraft turned to catch this final look at Saturn's moon Pandora next to the thin line of the F ring.
Спойлер
Over the course of its mission, Cassini helped scientists understand that Pandora plays a smaller role than they originally thought in shaping the narrow ring. When Cassini arrived at Saturn, many thought that Pandora and Prometheus worked together to shepherd the F ring between them, confining it and sculpting its unusual braided and kinked structures. However, data fr om Cassini show that the gravity of the two moons together actually stirs the F ring into a chaotic state, generating the "gap and streamer" structure seen elsewhere (see also F Ring Patterns).

Recent models, supported by Cassini images, suggest that it is Prometheus alone, not Pandora, that confines the bulk of the F ring, aided by the particular characteristics of its orbit.  Prometheus establishes stable locations for F ring material wh ere the moon's own gravitational resonances are least cluttered by the perturbing influence of its sibling satellite, Pandora.

This view looks toward the sunlit side of the rings from about 28 degrees above the ringplane. The image was taken in visible light with the Cassini spacecraft narrow-angle camera on Sept. 14, 2017.

The view was obtained at a distance of approximately 360,000 miles (577,000 kilometers) from Pandora and at a Sun-Pandora-spacecraft, or phase, angle of 119 degrees. Image scale is about 2.2 miles (3.5 kilometers) per pixel.

The Cassini spacecraft ended its mission on Sept. 15, 2017.

The Cassini mission is a cooperative project of NASA, ESA (the European Space Agency) and the Italian Space Agency. The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the mission for NASA's Science Mission Directorate, Washington. The Cassini orbiter and its two onboard cameras were designed, developed and assembled at JPL. The imaging operations center is based at the Space Science Institute in Boulder, Colorado.

For more information about the Cassini-Huygens mission visit https://saturn.jpl.nasa.gov and https://www.nasa.gov/cassini. The Cassini imaging team homepage is at http://ciclops.org.
 
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https://www.nasa.gov/feature/jpl/powering-saturns-active-ocean-moon

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https://saturn.jpl.nasa.gov/news/3130/powering-saturns-active-ocean-moon/
ЦитироватьNov. 6, 2017

Powering Saturn's Active Ocean Moon


A recent study has provided new insights into how the warm interior of Saturn's geologically active moon Enceladus could be sustained for billions of years.
Credits: NASA/JPL/Space Science Institute
Full image and caption

Heat fr om friction could power hydrothermal activity on Saturn's moon Enceladus for billions of years if the moon has a highly porous core, according to a new modeling study by European and U.S. researchers working on NASA's Cassini mission.
Спойлер
The study, published today in the journal Nature Astronomy, helps resolve a question scientists have grappled with for a decade:  Where does the energy to power the extraordinary geologic activity on Enceladus come from?

Cassini found that Enceladus sprays towering, geyser-like jets of water vapor and icy particles, including simple organics, fr om warm fractures near its south pole. Additional investigation revealed the moon has a global ocean beneath its icy crust, from which the jets are venting into space. Multiple lines of evidence from Cassini indicate that hydrothermal activity -- hot water interacting chemically with rock -- is taking place on the seafloor.

One of those lines was the detection of tiny rock grains inferred to be the product of hydrothermal chemistry taking place at temperatures of at least 194 degrees Fahrenheit (90 degrees Celsius). The amount of energy required to produce these temperatures is more than scientists think could be provided by decay of radioactive elements in the interior.


This graphic from ESA (the European Space Agency) illustrates how water might be heated inside Saturn's moon Enceladus.
Credits: ESA/NASA/JPL-Caltech/SSI/LPG-CNRS/U. Nantes/U. Angers
Full image and caption

"Wh ere Enceladus gets the sustained power to remain active has always been a bit of a mystery, but we've now considered in greater detail how the structure and composition of the moon's rocky core could play a key role in generating the necessary energy," said the study's lead author, Gaël Choblet from the University of Nantes in France.

Choblet and co-authors found that a loose, rocky core with 20 to 30 percent empty space would do the trick. Their simulations show that as Enceladus orbits Saturn, rocks in the porous core flex and rub together, generating heat. The loose interior also allows water from the ocean to percolate deep down, wh ere it heats up, then rises, interacting chemically with the rocks. The models show this activity should be at a maximum at the moon's poles. Plumes of the warm, mineral-laden water gush from the seafloor and travel upward, thinning the moon's ice shell from beneath to only half a mile to 3 miles (1 to 5 kilometers) at the south pole. (The average global thickness of the ice is thought to be about 12 to 16 miles, or 20 to 25 kilometers.) And this same water is then expelled into space through fractures in the ice.

The study is the first to explain several key characteristics of Enceladus observed by Cassini: the global ocean, internal heating, thinner ice at the south pole, and hydrothermal activity. It doesn't explain why the north and south poles are so different though. Unlike the tortured, geologically fresh landscape of the south, Enceladus' northern extremes are heavily cratered and ancient. The authors note that if the ice shell was slightly thinner in the south to begin with, it would lead to runaway heating there over time.

The researchers estimate that, over time (between 25 and 250 million years), the entire volume of Enceladus' ocean passes through the moon's core. This is estimated to be an amount of water equal to two percent of the volume of Earth's oceans.

Flexing of Enceladus' icy crust due to the tidal pull of Saturn had previously been considered as a heat source, but models showed this would not produce enough sustained power. The ocean in Enceladus would have frozen within 30 million years. Although past studies modeled how tidal friction could generate heat in the moon's core, they made simpler assumptions or simulated the moon in only two dimensions. The new study ramped up the complexity of the model and simulated Enceladus in 3-D.

Although the Cassini science team had suspected for years that a porous core might play an important role in the mystery of Enceladus' warm interior, this study brings together several more recent lines of evidence in a very elegant way, according to NASA's Cassini Project Scientist Linda Spilker at the agency's Jet Propulsion Laboratory in Pasadena, California. "This powerful research makes use of newer details -- namely that the ocean is global and has hydrothermal activity -- that we just didn't have until the past couple of years. It's an insight that the mission needed time to build, one discovery upon another," she said.

Launched in 1997, the Cassini spacecraft orbited Saturn from 2004 to 2017. Cassini made numerous dramatic discoveries, including the surprising activity on Enceladus and liquid methane seas on Saturn's largest moon, Titan. Cassini ended its journey with a dramatic plunge into Saturn's atmosphere on Sept. 15, 2017, returning unique science data until it lost contact with Earth.

The Cassini-Huygens mission is a cooperative project of NASA, ESA (European Space Agency) and the Italian Space Agency. NASA's Jet Propulsion Laboratory, a division of Caltech in Pasadena, manages the mission for NASA's Science Mission Directorate, Washington. JPL designed, developed and assembled the Cassini orbiter.

More information about Cassini:

Preston Dyches
 Jet Propulsion Laboratory, Pasadena, Calif.
 818-394-7013
preston.dyches@jpl.nasa.gov


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Last Updated: Nov. 7, 2017
Editor: Tony Greicius

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https://ria.ru/science/20171107/1508327215.html
ЦитироватьУченые НАСА раскрыли секрет существования океана на Энцеладе
МОСКВА, 7 ноя – РИА Новости. Потенциально обитаемый подледный океан существует на Энцеладе благодаря тому, что его ядро содержит в себе большое количество пор, которые постоянно сжимаются и разжимаются притяжением Сатурна, говорится в статье, опубликованной в журнале Nature Astronomy.
"То, откуда Энцелад берет энергию для разогрева своего океана, достаточно долго оставалось тайной для нас. Мы детально проанализировали то, как структура его ядра и химический состав могут влиять на процесс ее выработки, используя последние данные, полученные "Кассини", — заявил Гаэль Шобле (Gaël Choblet) из университета Нанта (Франция).
В 2005 году "Кассини" обнаружил на Энцеладе струи из частиц водяного льда и пара, которые выбрасываются в космическое пространство из параллельных трещин вблизи южного полюса — так называемых "тигровых полос". Это открытие поставило перед учеными вопрос об источнике этого пара и льда.
Через 10 лет после открытия тигровых полос и гейзеров на Энцеладе, зонд "Кассини" показал, что в недрах этого спутника Сатурна присутствует глобальный океан из жидкой и горячей воды, обнаружив частицы песка и замороженные капли воды, выброшенные с южного полюса Энцелада вместе с извержениями гейзеров.
Открытие этого океана и первые данные по его свойствам поставили планетологов в тупик – относительно большая глубина океана и небольшая толщина ледовой "крышки", покрывающей его, однозначно указали на то, что этот водный мир давно должен был замерзнуть.
Тем не менее, этого не произошло, и открытие горячих гейзеров и следов геотермальной активности в окрестностях луны Сатурна указало на обратный факт – вода в недрах Энцелада не остывает, а постоянно подогревается. Источником этого тепла могут быть приливные силы, постоянно растягивающие и сжимающие каменистое ядро Энцелада, однако их, как показали расчеты ученых, было явно недостаточно для того, чтобы океан планеты оставался жидким миллионы лет.
Шобле и его коллеги нашли объяснение этой загадке, изучая данные по структуре недр Энцелада, собранные "Кассини" незадолго до кончины зонда в середине сентября этого года. Сравнивая то, как облик луны Сатурна менялся по мере ее удаления и сближения с "властелином колец", ученые пришли к выводу, что ядро Энцелада похоже по своему устройству на швейцарский сыр.
Иными словами, каменистое ядро планеты содержит в себе множество пустот, занимающих, как показывают расчеты планетологов, примерно 20-30% от его общего объема. Эти "сырные дыры", как рассказывает Шобле, играют роль своеобразного "кипятильника" – проникающая в них вода нагревается, взаимодействует с породами ядра и переносит тепло в другие части океана.
Подобный сценарий, по словам планетологов, хорошо согласуется с тем, почему гейзеры расположены на южном полюсе Энцелада – большая часть теплых потоков воды, вырабатываемых ядром, будет сосредоточена в окрестностях полюсов планеты. Эти течения будут "подтачивать" лед и повышать вероятность формирования крупных трещин, через которые теплая вода океана сможет периодически вырываться в космос.
Несмотря на подобное сходство результатов расчетов и реальных данных с "Кассини", у этой теории, как признают сами ученые, есть один недостаток – она не объясняет того, почему на северном полюсе Энцелада нет гейзеров. Как предполагают ученые, это связано с тем, что ледовая оболочка планеты могла быть изначально асимметричной, благодаря чему гейзеры на южном полюсе возникли гораздо быстрее, чем они могли появиться на севере.
Как показывают расчеты ученых, подобная "грелка" может перекачивать через себя фактически всю воду в океане Энцелада за достаточно короткое время, около 25 миллионов лет, что означает, что данный "водоем" может существовать на луне Сатурна фактически с момента ее рождения.
Его долгое существование, как считают планетологи, заметно повышает вероятность зарождения и существования жизни в океане луны Сатурна в том случае, если там есть нужные для этого ингредиенты.
Замечательно! Непонятное существование "тёплого" океана заменили "совершенно понятным" пористым ядром. Осталось только понять как оно получилось!

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https://saturn.jpl.nasa.gov/resources/7810/
ЦитироватьSo Long, C Ring



Photojournal: PIA21356

November 13, 2017

Saturn's C ring is home to a surprisingly rich array of structures and textures (see also PIA21618). Much of the structure seen in the outer portions of Saturn's rings is the result of gravitational perturbations on ring particles by moons of Saturn.
Спойлер
Such interactions are called resonances. However, scientists are not clear as to the origin of the structures seen in this image which has captured an inner ring region sparsely populated with particles, making interactions between ring particles rare, and with few satellite resonances.

In this image, a bright and narrow ringlet located toward the outer edge of the C ring is flanked by two broader features called plateaus, each about 100 miles (160 kilometers) wide.

Plateaus are unique to the C ring. Cassini data indicates that the plateaus do not necessarily contain more ring material than the C ring at large, but the ring particles in the plateaus may be smaller, enhancing their brightness.

This view looks toward the sunlit side of the rings from about 53 degrees above the ring plane. The image was taken in green light with the Cassini spacecraft narrow-angle camera on Aug. 14, 2017.

The view was acquired at a distance of approximately 117,000 miles (189,000 kilometers) from Saturn and at a Sun-Saturn-spacecraft, or phase, angle of 74 degrees. Image scale is 3,000 feet (1 kilometer) per pixel.

The Cassini spacecraft ended its mission on Sept. 15, 2017.

The Cassini mission is a cooperative project of NASA, ESA (the European Space Agency) and the Italian Space Agency. The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the mission for NASA's Science Mission Directorate, Washington. The Cassini orbiter and its two onboard cameras were designed, developed and assembled at JPL. The imaging operations center is based at the Space Science Institute in Boulder, Colorado.

For more information about the Cassini-Huygens mission visit https://saturn.jpl.nasa.gov and https://www.nasa.gov/cassini. The Cassini imaging team homepage is at http://ciclops.org.
 
Credit

NASA/JPL-Caltech/Space Science Institute

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https://saturn.jpl.nasa.gov/resources/7811/
ЦитироватьAbove Rhea



Photojournal: PIA21354

November 20, 2017

This image is from Cassini's final observation of Saturn's icy moon Rhea (949 miles or 1,527 kilometers across) on May 2, 2017. The spacecraft was at the time high above the plane of Saturn's rings, looking down at Rhea's northern hemisphere. The northern rim of the giant Tirawa impact basin can be seen along the limb at left. (For a high-resolution view of Rhea, see Rhea: Full Moon; Tirawa is the large basin at the one o'clock position in that view.)
Спойлер
The image was taken in visible light with the Cassini spacecraft narrow-angle camera at a distance of approximately 230,000 miles (370,000 kilometers) from Rhea. Image scale is 1.2 miles (2 kilometers) per pixel.

The Cassini spacecraft ended its mission on Sept. 15, 2017.

The Cassini mission is a cooperative project of NASA, ESA (the European Space Agency) and the Italian Space Agency. The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the mission for NASA's Science Mission Directorate, Washington. The Cassini orbiter and its two onboard cameras were designed, developed and assembled at JPL. The imaging operations center is based at the Space Science Institute in Boulder, Colorado.

For more information about the Cassini-Huygens mission visit https://saturn.jpl.nasa.gov and https://www.nasa.gov/cassini. The Cassini imaging team homepage is at http://ciclops.org.

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NASA/JPL-Caltech/Space Science Institute

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https://saturn.jpl.nasa.gov/news/3131/cassini-image-mosaic-a-farewell-to-saturn/

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https://www.jpl.nasa.gov/news/news.php?feature=7008
ЦитироватьNovember 21, 2017

Cassini Image Mosaic: A Farewell to Saturn


After more than 13 years at Saturn, and with its fate sealed, NASA's Cassini spacecraft bid farewell to the Saturnian system by firing the shutters of its wide-angle camera and capturing this last, full mosaic of Saturn and its rings two days before the spacecraft's dramatic plunge into the planet's atmosphere. Full image and caption

In a fitting farewell to the planet that had been its home for over 13 years, the Cassini spacecraft took one last, lingering look at Saturn and its splendid rings during the final leg of its journey and snapped a series of images that has been assembled into a new mosaic.
Спойлер
Cassini's wide-angle camera acquired 42 red, green and blue images, covering the planet and its main rings from one end to the other, on Sept. 13, 2017. Imaging scientists stitched these frames together to make a natural color view. The scene also includes the moons Prometheus, Pandora, Janus, Epimetheus, Mimas and Enceladus.

There is much to remember and celebrate in marking the end of the mission. Cassini's exploration of Saturn and its environs was deep, comprehensive and historic.

"Cassini's scientific bounty has been truly spectacular -- a vast array of new results leading to new insights and surprises, from the tiniest of ring particles to the opening of new landscapes on Titan and Enceladus, to the deep interior of Saturn itself," said Robert West, Cassini's deputy imaging team leader at NASA's Jet Propulsion Laboratory in Pasadena, California.

The Cassini imaging team had been planning this special farewell view of Saturn for years. For some, when the end finally came, it was a difficult goodbye.

"It was all too easy to get used to receiving new images from the Saturn system on a daily basis, seeing new sights, watching things change," said Elizabeth Turtle, an imaging team associate at the Johns Hopkins University Applied Physics Laboratory, Laurel, Maryland. "It was hard to say goodbye, but how lucky we were to be able to see it all through Cassini's eyes!"

For others, Cassini's farewell to Saturn is reminiscent of another parting from long ago.

"For 37 years, Voyager 1's last view of Saturn has been, for me, one of the most evocative images ever taken in the exploration of the solar system," said Carolyn Porco, former Voyager imaging team member and Cassini's imaging team leader at the Space Science Institute in Boulder, Colorado. "In a similar vein, this 'Farewell to Saturn' will forevermore serve as a reminder of the dramatic conclusion to that wondrous time humankind spent in intimate study of our Sun's most iconic planetary system."

Launched in 1997, the Cassini spacecraft orbited Saturn from 2004 to 2017. The mission made numerous dramatic discoveries, including the surprising geologic activity on Saturn's moon Enceladus and liquid methane seas on Saturn's largest moon, Titan. Cassini ended its journey with a dramatic plunge into Saturn's atmosphere on Sept. 15, 2017, returning unique science data until it lost contact with Earth.

The Cassini-Huygens mission is a cooperative project of NASA, ESA (European Space Agency) and the Italian Space Agency. NASA's Jet Propulsion Laboratory, a division of Caltech in Pasadena, manages the mission for NASA's Science Mission Directorate, Washington. The Cassini orbiter and its two onboard cameras were designed, developed and assembled at JPL. The imaging team consists of scientists from the U.S., England, France, and Germany. The imaging operations center and team leader are based at the Space Science Institute in Boulder, Colorado.
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https://saturn.jpl.nasa.gov/resources/7812/
ЦитироватьAlpha and Omega



Photojournal: PIA21353

November 27, 2017

These two images illustrate just how far Cassini traveled to get to Saturn. On the left is one of the earliest images Cassini took of the ringed planet, captured during the long voyage fr om the inner solar system. On the right is one of Cassini's final images of Saturn, showing the site wh ere the spacecraft would enter the atmosphere on the following day.
Спойлер
In the left image, taken in 2001, about six months after the spacecraft passed Jupiter for a gravity assist flyby, the best view of Saturn using the spacecraft's high-resolution (narrow-angle) camera was on the order of what could be seen using the Earth-orbiting Hubble Space Telescope. At the end of the mission (at right), from close to Saturn, even the lower resolution (wide-angle) camera could capture just a tiny part of the planet.

The left image looks toward Saturn from 20 degrees below the ring plane and was taken on July 13, 2001 in wavelengths of infrared light centered at 727 nanometers using the Cassini spacecraft narrow-angle camera. The view at right is centered on a point 6 degrees north of the equator and was taken in visible light using the wide-angle camera on Sept. 14, 2017.

The view on the left was acquired at a distance of approximately 317 million miles (510 million kilometers) from Saturn. Image scale is about 1,900 miles (3,100 kilometers) per pixel. The view at right was acquired at a distance of approximately 360,000 miles (579,000 kilometers) from Saturn. Image scale is 22 miles (35 kilometers) per pixel.

The Cassini spacecraft ended its mission on Sept. 15, 2017.

The Cassini mission is a cooperative project of NASA, ESA (the European Space Agency) and the Italian Space Agency. The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the mission for NASA's Science Mission Directorate, Washington. The Cassini orbiter and its two onboard cameras were designed, developed and assembled at JPL. The imaging operations center is based at the Space Science Institute in Boulder, Colorado.

For more information about the Cassini-Huygens mission visit https://saturn.jpl.nasa.gov and https://www.nasa.gov/cassini. The Cassini imaging team homepage is at http://ciclops.org.

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NASA/JPL-Caltech/Space Science Institute

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https://dni24.com/exclusive/147728-dannye-cassini-kolca-saturna-znachitelno-molozhe-planet-solnechnoy-sistemy.html
ЦитироватьДанные Cassini: Кольца Сатурна значительно моложе планет Солнечной системы
Кольца Сатурна кажутся древними постоянными светильниками в Cолнечной системе. Но наблюдения, сделанные в последние месяцы до гибели космического корабля NASA Cassini, показывают, что они удивительно молоды: нескольких сотен миллионов лет назад их не было. Сатурн приобрел свои известные кольца относительно поздно. Удивительно, но во время динозавров на небе вращался «голый» Сатурн.
«Именно тогда какая-то катастрофа поразила газового гиганта. Возможно, бродячая комета или астероид столкнулись с ледяной луной, выбросив ее остатки на орбиту. Или, может быть, орбиты спутников Сатурна каким-то образом сдвинулись, и в результате смещения гравитации луна разделилась. Однако, как бы то ни было, данные Cassini дают понять, что кольца не существовали при зарождении Солнечной системы 4,5 миллиарда лет назад» - говорит Джефф Кауцци, специалист по кольцевым исследованиям в исследовании Ames NASA Центр в Маунтин-Вью, Калифорния.
Доказательством этой гипотезы служит масса колец. В течение нескольких десятков лет многие ученые считали их массу большей, чем у луны Сатурна Мимаса из-за непрозрачного, плотного появления первичного кольца Сатурна, кольца B. Данные, собранные Cassini перед погружением в планету, показали массу B-кольца. Во время прохождения Cassini в разрыве между Сатурном и его кольцами во время его последних проходов эксперты смогли измерять гравитационное притяжение колец - и, следовательно, их массу. «Это явное указание на то, что кольца не образуются вместе с Сатурном». – сообщают в NASA.
Кроме того, еще одним доказательством в пользу молодости колец Сатурна является постоянный дождь сажистых микрометеоритов, падающих на планету с краю Солнечной системы, что, как ожидается, должно будет затемнить девственный водный лед в кольцах с течением времени. Как быстро они темнеют, зависит от скорости бомбардировки. После 12 лет кропотливых измерений и анализа Cassini, измерял мелкие частицы потока микрометеоритов и они оказались несовместимы со «старыми» кольцами. «Эти два результата данных Cassini действительно подтверждают молодость колец, возраст которых приблизительно до 200 миллионов лет», - считает Ларри Эспозито, планетарный ученый NASA.

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https://saturn.jpl.nasa.gov/news/3135/lost-in-space-a-part-of-cassini-is-still-out-there/
ЦитироватьDecember 22, 2017

Lost in Space: A Part of Cassini is Still Out There


The CDA instrument, covered in its protective thermal blankets. Image credit: NASA/JPL-Caltech

On Sept. 15, 2017, the incredible journey of the Cassini mission to Saturn came to an end. The spacecraft vanished into the planet at a speed of about 75,000 mph (120,000 kph), like a shooting star streaking across Saturn's sky. In the end, Cassini became part of the planet itself.

The science team of the mission's Cosmic Dust Analyzer (CDA) instrument, led by Ralf Srama of the University of Stuttgart, points out that one part of Cassini was able to survive the fantastic 20-year-long journey. Almost forgotten over time, one metallic piece survived and is still travelling through space. In 1997, during the spacecraft's early cruise phase, when Cassini was still in the vicinity of the Earth, the aluminum cover of the CDA was jettisoned in order to open the instrument's aperture. This early cover release was necessary in order to begin measurements of the interplanetary and interstellar dust background.

Slowly tumbling through space, the cover with a mass of two mobile phones travels on an Earth-like orbit and with an approximate speed of 19 miles per second (30 kilometers per second). Models show that the trajectory sometimes brings the cover close to both Venus and Earth. In 2007, the cover came as close as about 2.5 million miles (4 million kilometers) to Earth, which corresponds to roughly 10 times the distance between Earth and the Moon. Although not confirmed, due to its highly reflective surface, the cover might, in principle, be observable from Earth by larger telescopes. The CDA team investigated whether the cover might collide with Earth and burn up in our atmosphere as a meteor, and they were able to rule out this possibility for at least the next 50 years.