"Кассини" !

[tnt22]

CassiniSaturn‏Подлинная учетная запись @CassiniSaturn 10 мин. назад

Ring crossing #17 of 22 in our #GrandFinale was a success. The next will take place on Aug. 14. Ride along at http://saturn.jpl.nasa.gov

[tnt22]

https://saturn.jpl.nasa.gov/news/3091/nine-ways-cassini-matters-no-8/

August 5, 2017

Nine Ways Cassini Matters: No. 8

Cassini represents a staggering achievement of human and technical complexity, finding innovative ways to use the spacecraft and its instruments, and paving the way for future missions to explore our solar system.

The Cassini-Huygens mission is an international collaboration involving three space agencies, with 19 countries contributing hardware to the flight system. The Cassini spacecraft carries 12 instruments, Huygens carried six more, and scientists fr om 26 nations are participating in the investigations. Among the many pioneering technologies of the mission are new solid-state data recorders with no moving parts that have since replaced tape recorders, solid-state power switches (space-based versions of circuit breakers), and advanced solid-state electronics.

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The spacecraft has over 9 miles (14 kilometers) of cabling and 22,000 connections.

...

Cassini was able explore the entire Saturn system in a way inconceivable with conventional propulsion. Building on the techniques used by the Galileo mission to Jupiter, Cassini mission planners designed flybys of the moon Titan to utilize the moon's gravity to navigate around the Saturn system and maximize the science return of the mission. Titan became, in a way, Cassini's virtual "gas station" since the spacecraft couldn't possibly have brought enough fuel for a tour this long and complex. Each of Cassini's 127 targeted Titan flybys changed the spacecraft's velocity (on average) by as much as the entire Saturn orbit insertion burn. The exquisite optimization techniques developed during Cassini will enable planning for future exploration that can use similar approachs. Chief among these opportunities is NASA's planned mission to explore Jupiter's moon Europa using multiple flybys, known as the Europa Clipper.

Over the course of almost 20 years in space, Cassini also showed that you can teach an old dog new tricks, as the mission team found new ways to use its instruments and engineering systems that their designers had not foreseen.

Cassini has required an extremely complex schedule for determining which instrument's observations can be made at any given moment. Cassini's intricate observation sequences, often timed to fractions of a second, are frequently planned many months or years before they are executed by the spacecraft. The collaboration between multiple teams with often differing objectives has become an exemplary model for future missions.

Over the course of almost 20 years in space, Cassini also showed that you can teach an old dog new tricks, as the mission team found new ways to use its instruments and engineering systems that their designers had not foreseen. These include using the radar instrument to plumb the depths of Titan's seas; tasting the plume of Enceladus with instruments meant to sample Titan's atmosphere; scanning the rings with a radar originally designed to bounce signals off of Titan's surface; and having the Deep Space Network's highly accurate frequency reference fill in for the radio science instrument's lost ultra-stable onboard frequency reference. In a unique collaboration, the attitude control and navigation teams joined with the instrument teams to develop a consolidated model of Titan's atmosphere. Cassini will finish its mission repurposing the instruments that sniffed Titan's atmosphere and Enceladus' plume once more, this time to sample the Saturn atmosphere itself.

The mission has also had some rather surprising earthly benefits. A Cassini resource exchange, created prior to launch to help team members trade and effectively share power, mass, data rates and budget, has become a model for how to manage other types of international collaboration, including carbon trading.

When Cassini plunges into Saturn's atmosphere, it will have spent nearly every last drop of fuel it's carrying, a fitting end to a spacecraft that pushed itself to the lim it...and in many ways, beyond.

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[tnt22]

CassiniSaturn‏Подлинная учетная запись @CassiniSaturn 2 ч. назад

We're about to start the final five orbits of the #GrandFinale, ultra-close passes through Saturn's upper atmosphere https://go.nasa.gov/2vFluKo

https://saturn.jpl.nasa.gov/news/3098/cassini-to-begin-final-five-orbits-around-saturn/

August 9, 2017
Cassini to Begin Final Five Orbits Around Saturn

NASA's Cassini spacecraft will enter new territory in its final mission phase, the Grand Finale, as it prepares to embark on a set of ultra-close passes through Saturn's upper atmosphere with its final five orbits around the planet.

Cassini will make the first of these five passes over Saturn at 9:22 p.m. PDT Sunday, Aug. 13 (12:22 a.m. EDT Monday, Aug. 14). The spacecraft's point of closest approach to Saturn during these passes will be between about 1,010 and 1,060 miles (1,630 and 1,710 kilometers) above Saturn's cloud tops.

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This artist's rendering shows Cassini as the spacecraft makes one of its final five dives through Saturn's upper atmosphere in August and September 2017. Credit: NASA/JPL-Caltech

The spacecraft is expected to encounter atmosphere dense enough to require the use of its small rocket thrusters to maintain stability -- conditions similar to those encountered during many of Cassini's close flybys of Saturn's moon Titan, which has its own dense atmosphere.
 

This view fr om Cassini shows the narrow band of Saturn's atmosphere, which Cassini will dive through five times before making its final plunge into the planet on Sept. 15. Credit: NASA/JPL-Caltech
 
"Cassini's Titan flybys prepared us for these rapid passes through Saturn's upper atmosphere," said Earl Maize, Cassini project manager at NASA's Jet Propulsion Laboratory in Pasadena, California. "Thanks to our past experience, the team is confident that we understand how the spacecraft will behave at the atmospheric densities our models predict."

Maize said the team will consider the Aug. 14 pass nominal if the thrusters operate between 10 and 60 percent of their capability. If the thrusters are forced to work harder -- meaning the atmosphere is denser than models predict -- engineers will increase the altitude of subsequent orbits. Referred to as a "pop-up maneuver," thrusters will be used to raise the altitude of closest approach on the next passes, likely by about 120 miles (200 kilometers).

If the pop-up maneuver is not needed, and the atmosphere is less dense than expected during the first three passes, engineers may alternately use the "pop-down" option to lower the closest approach altitude of the last two orbits, also likely by about 120 miles (200 kilometers). Doing so would enable Cassini's science instruments, especially the ion and neutral mass spectrometer (INMS), to obtain data on the atmosphere even closer to the planet's cloud tops.

"As it makes these five dips into Saturn, followed by its final plunge, Cassini will become the first Saturn atmospheric probe," said Linda Spilker, Cassini project scientist at JPL. "It's long been a goal in planetary exploration to send a dedicated probe into the atmosphere of Saturn, and we're laying the groundwork for future exploration with this first foray."

Other Cassini instruments will make detailed, high-resolution observations of Saturn's auroras, temperature, and the vortexes at the planet's poles. Its radar will peer deep into the atmosphere to reveal small-scale features as fine as 16 miles (25 kilometers) wide -- nearly 100 times smaller than the spacecraft could observe prior to the Grand Finale.

On Sept. 11, a distant encounter with Titan will serve as a gravitational version of a large pop-down maneuver, slowing Cassini's orbit around Saturn and bending its path slightly to send the spacecraft toward its Sept. 15 plunge into the planet.

During the half-orbit plunge, the plan is to have seven Cassini science instruments, including INMS, turned on and reporting measurements in near real time. The spacecraft is expected to reach an altitude wh ere atmospheric density is about twice what it encountered during its final five passes. Once Cassini reaches that point, its thrusters will no longer be able to work against the push of Saturn's atmosphere to keep the spacecraft's antenna pointed toward Earth, and contact will permanently be lost. The spacecraft will break up like a meteor moments later, ending its long and rewarding journey.

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.

News Media Contact

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

Felicia Chou
 NASA Headquarters, Washington
 202-358-0257
 felicia.chou@nasa.gov

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[tnt22]

CassiniSaturn‏Подлинная учетная запись @CassiniSaturn 34 мин. назад

Some of our best discoveries at Saturn were serendipitous: https://go.nasa.gov/2usOVzH

https://saturn.jpl.nasa.gov/news/3090/nine-ways-cassini-matters-no-7/

August 10, 2017
Nine Ways Cassini Matters: No. 7

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A masterpiece of deep time and wrenching gravity, the tortured surface of Saturn's moon Enceladus and its fascinating ongoing geologic activity tell the story of the ancient and present struggles of one tiny world.

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Some of Cassini's best discoveries were serendipitous. What Cassini found at Saturn prompted scientists to rethink their understanding of the solar system.

You can only get to know a planet so well with remote and sporadic observations. To truly understand the dynamics of a place as complicated and interesting as Saturn, you have to go there and stay to explore.

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Towering jets of ice and water vapor pouring out of a moon as tiny as Enceladus were a huge surprise (explaining why Voyager flybys in the early 1980s saw that the moon had a young surface), as was the later finding that the moon has an ocean under its icy crust. Scientists also had not expected to find Saturn's magnetosphere -- the region around the planet strongly influenced by Saturn's magnetic field -- to be filled with an electrically excited gas, or plasma, of oxygen. It turned out this was another surprise fr om Enceladus, as the water vapor from its plume is broken apart by sunlight and the liberated oxygen spreads out through Saturn's magnetic bubble. Cassini detected this oxygen on approach to Saturn, but its origin was perplexing at first.

No one knew for sure what kind of environment ESA's Huygens probe would find when it came to rest on Titan's surface, so Huygens was built either to land on hard ground or float, if need be. Cassini later showed scientists that most of the moon's lakes and seas were near the north pole, and most of the moon's landscape was more like the Arizona desert. Cassini also observed a surprisingly rich variety of complex, organic chemicals forming in Titan's atmosphere.

Another unexpected finding -- which endures as a mystery -- is the irregularity of Saturn's day (how long the planet takes to make one rotation on its axis). At Jupiter, a beacon-like burst of radio waves known as "kilometric radiation" beams out with clock-like regularity once a day. But Saturn's kilometric radiation isn't consistent. It's somewh ere between 10.6 and 10.8 hours. That might not seem like a big discrepancy, but for such a fundamental property as the planet's rotation period, it's frustratingly imprecise for scientists. They hope to settle the score by the time the mission ends by flying Cassini close enough to the planet to tease out the true answer from the magnetic field.

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https://saturn.jpl.nasa.gov/mission/grand-finale/grand-finale-orbit-guide/#Orbit_18

IN PROGRESS: Orbit 288 - August 10 - August 17

[TH]Event[/TH][TH]Date[/TH][TH]Spacecraft Time (UTC)[/TH][TH]Local Time (PDT)[/TH][TH]Notes[/TH][TH]Apoapse[/TH][TH]Periapse[/TH][TH]Downlink[/TH]

Aug 10	10:56 p.m.	3:56 p.m.
Aug 14	4:22 a.m.	9:22 p.m. (Aug 13)	First of the "Final Five" dips into Saturn's atmosphere.
Aug 15	12:26 a.m.	5:26 p.m. (Aug 14)	Estimated Earth Received Time (ERT) is 6:45 p.m. PDT on August 14.

[/li]
• 
  Cassini has just five orbits of Saturn remaining before the mission ends.
• During this orbit, Cassini's Composite Infrared Spectrometer (CIRS) observes the edge of Saturn's atmosphere to determine different temperatures at different altitudes.
• 
  The spacecraft's imaging cameras, the Imaging Science Subsystem (ISS), then observe mysterious features informally called "streaks" in Saturn's C ring.
• 
  This is the first of five orbits in which Cassini's elliptical orbit carries it so low that the spacecraft passes briefly through Saturn's outermost atmosphere. Cassini's reaction control thrusters are at the ready to correct the spacecraft's orientation in case Saturn's atmosphere pushes on the spacecraft hard enough to cause any rotation.
• 
  During the period in which the spacecraft is nearest Saturn, Cassini's Ion and Neutral Mass Spectrometer (INMS) performs the first ever direct sampling of Saturn's  atmosphere. The instrument measures densities of different species of molecular hydrogen, helium and a variety of ions in the immediate vicinity of the spacecraft.
• 
  Cassini's RADAR instrument operates at the same time as INMS, studying Saturn's atmosphere in a passive mode to study the small-scale structure and ammonia concentration of Saturn's atmosphere.
• 
  During this orbit, Cassini gets within 1,060 miles (1,710 kilometers) of Saturn's 1-bar level. Cassini also passes within 3,720 miles (5,990 kilometers) of the inner edge of Saturn's D ring.
  

[tnt22]

CassiniSaturn‏Подлинная учетная запись @CassiniSaturn 6 мин назад

Happening now: first of final five orbits now underway. Follow along at: https://go.nasa.gov/2aNCy6t  Orbit guide: https://go.nasa.gov/2qcf2Vx

[tnt22]

CassiniSaturn‏Подлинная учетная запись @CassiniSaturn 29 мин. назад

Saturn's planet-sized moon Titan: enigma, challenge and the true engine of our mission - https://go.nasa.gov/2uOk3oq 

(3:11)

https://saturn.jpl.nasa.gov/news/3099/cassini-prepares-to-say-goodbye-to-a-true-titan/

August 11, 2017
Cassini Prepares to Say Goodbye to a True Titan

Mere weeks away fr om its dramatic, mission-ending plunge into Saturn, NASA's Cassini spacecraft has a hectic schedule, orbiting the planet every week in its Grand Finale. On a few orbits, Saturn's largest moon, Titan, has been near enough to tweak Cassini's orbit, causing the spacecraft to approach Saturn a bit closer or a bit farther away. A couple of those distant passes even pushed Cassini into the inner fringes of Saturn's rings.

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These two views of Saturn's moon Titan exemplify how NASA's Cassini spacecraft has revealed the surface of this fascinating world. > Full image and caption

Titan will be waiting once again when the road runs out in September. A last, distant encounter with the moon on Sept. 11 will usher Cassini to its fate, with the spacecraft sending back precious science data until it loses contact with Earth.

But this gravitational pushing and shoving isn't a new behavior for Titan. It's been doing that all along, by design.

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The True Engine of the Mission

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Repeated flybys of Titan were envisioned, from the mission's beginning, as a way to explore the mysterious planet-size moon and to fling Cassini toward its adventures in the Saturn system. Scientists had been eager for a return to Titan since NASA's Voyager 1 spacecraft flew past in 1980 and was unable to see through the dense, golden haze that shrouds its surface.

Titan is just a bit larger than the planet Mercury. Given its size, the moon has significant gravity, which is used for bending Cassini's course as it orbits Saturn. A single close flyby of Titan could provide more of a change in velocity than the entire 90-minute engine burn the spacecraft needed to slow down and be captured by Saturn's gravity upon its arrival in 2004.

The mission's tour designers -- engineers tasked with plotting the spacecraft's course, years in advance -- used Titan as their linchpin. Frequent passes by the moon provided the equivalent of huge amounts of rocket propellant. Using Titan, Cassini's orbit could be stretched out, farther from Saturn -- for example, to send the spacecraft toward the distant moon Iapetus. With this technique, engineers used Titan flybys to change the orientation of Cassini's orbit many times during the mission; for example, lifting the spacecraft out of the plane of the rings to view them from high above, along with high northern and southern latitudes on Saturn and its moons.

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What We've Learned

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Over the course of its 13-year mission at Saturn, Cassini has made 127 close flybys of Titan, with many more-distant observations. Cassini also dropped off the European Space Agency's Huygens probe, which descended through Titan's atmosphere to land on the surface in January 2005.

Successes for Cassini during its mission include the revelation that, as researchers had theorized, there were indeed bodies of open liquid hydrocarbons on Titan's surface. Surprisingly, it turned out Titan's lakes and seas are confined to the poles, with almost all of the liquid being at northern latitudes in the present epoch. Cassini found that most of Titan has no lakes, with vast stretches of linear dunes closer to the equator similar to those in places like Namibia on Earth. The spacecraft observed giant hydrocarbon clouds hovering over Titan's poles and bright, feathery ones that drifted across the landscape, dropping methane rain that darkened the surface. There were also indications of an ocean of water beneath the moon's icy surface.

Early on, Cassini's picture of Titan was spotty, but every encounter built upon the previous one. Over the course of the entire mission, Cassini's radar investigation imaged approximately 67 percent of Titan's surface, using the spacecraft's large, saucer-shaped antenna to bounce signals off the moon's surface. Views from Cassini's imaging cameras, infrared spectrometer, and radar slowly and methodically added details, building up a more complete, high-resolution picture of Titan.

"Now that we've completed Cassini's investigation of Titan, we have enough detail to really see what Titan is like as a world, globally," said Steve Wall, deputy lead of Cassini's radar team at NASA's Jet Propulsion Laboratory in Pasadena, California.

Scientists now have enough data to understand the distribution of Titan's surface features (like mountains, dunes and seas) and the behavior of its atmosphere over time, and they have been able to begin piecing together how surface liquids might migrate from pole to pole.

Among the things that remain uncertain is exactly how the methane in Titan's atmosphere is being replenished, since it's broken down over time by sunlight. Scientists see some evidence of volcanism, with methane-laden water as the "lava," but a definitive detection remains elusive.

Cassini's long-term observations could still provide clues. Researchers have been watching for summer rain clouds to appear at the north pole, as their models predicted. Cassini observed rain clouds at the south pole in southern summer in 2004. But so far, clouds at high northern latitudes have been sparse.

"The atmosphere seems to have more inertia than most models have assumed. Basically, it takes longer than we thought for the weather to change with the seasons," said Elizabeth Turtle, a Cassini imaging team associate at Johns Hopkins Applied Physics Laboratory, Laurel, Maryland.

The sluggish arrival of northern summer clouds may match better with models that predict a global reservoir of methane, Turtle said. "There isn't a global reservoir at the surface, so if one exists in the subsurface that would be a major revelation about Titan." This points to the value of Cassini's long-term monitoring of Titan's atmosphere, she said, as the monitoring provides data that can be used to test models and ideas.

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Results from the Last Close Pass

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Cassini made its last close flyby of Titan on April 22. That flyby gave the spacecraft the push it needed to leap over Saturn's rings and begin its final series of orbits, which pass between the rings and the planet.

During that flyby, Cassini's radar was in the driver's seat -- its observation requirements determining how the spacecraft would be oriented as it passed low over the surface one last time at an altitude of 608 miles (979 kilometers). One of the priorities was to have one last look for the mysterious features the team dubbed "magic islands," which had appeared and then vanished in separate observations taken years apart. On the final pass there were no magic islands to be seen. The radar team is still working to understand what the features might have been, with leading candidates being bubbles or waves.

Most interesting to the radar team was a set of observations that was both the first and last of its kind, in which the instrument was used to sound the depths of several of the small lakes that dot Titan's north polar region. Going forward, the researchers will be working to tease out information from these data about the lakes' composition, in terms of methane versus ethane.

As Cassini zoomed past on its last close brush with Titan, headed toward its Grand Finale, the radar imaged a long swath of the surface that included terrain seen on the very first Titan flyby in 2004. "It's pretty remarkable that we ended up close to wh ere we started," said Wall. "The difference is how richly our understanding has grown, and how the questions we're asking about Titan have evolved."

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.

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More information about Cassini:

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https://www.nasa.gov/cassini

https://saturn.jpl.nasa.gov/

Media Contact:

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

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[tnt22]

CassiniSaturn‏Подлинная учетная запись @CassiniSaturn 4 ч. назад

Saturn's clouds appear like strokes fr om a cosmic brush thanks to the way fluids interact in the atmosphere https://go.nasa.gov/2fEvAoC 

https://saturn.jpl.nasa.gov/resources/7721/

Cloudy Waves (False Color)

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Photojournal: PIA21341

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August 14, 2017

Clouds on Saturn take on the appearance of strokes from a cosmic brush thanks to the wavy way that fluids interact in Saturn's atmosphere.

Neighboring bands of clouds move at different speeds and directions depending on their latitudes. This generates turbulence wh ere bands meet and leads to the wavy structure along the interfaces. Saturn's upper atmosphere generates the faint haze seen along the limb of the planet in this image.

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This false color view is centered on 46 degrees north latitude on Saturn. The images were taken with the Cassini spacecraft narrow-angle camera on May 18, 2017 using a combination of spectral filters which preferentially admit wavelengths of near-infrared light. The image filter centered at 727 nanometers was used for red in this image; the filter centered at 750 nanometers was used for blue. (The green color channel was simulated using an average of the two filters.)

The view was obtained at a distance of approximately 750,000 miles (1.2 million kilometers) from Saturn. Image scale is about 4 miles (7 kilometers) per pixel.

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 http://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.nasa.gov/image-feature/jpl/pia21625/highlighting-titans-hazes

Aug. 14, 2017

Highlighting Titan's Hazes


 
NASA's Cassini spacecraft looks toward the night side of Saturn's moon Titan in a view that highlights the extended, hazy nature of the moon's atmosphere. During its long mission at Saturn, Cassini has frequently observed Titan at viewing angles like this, where the atmosphere is backlit by the Sun, in order to make visible the structure of the hazes.

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Titan's high-altitude haze layer appears blue here, whereas the main atmospheric haze is orange. The difference in color could be due to particle sizes in the haze. The blue haze likely consists of smaller particles than the orange haze.

Images taken using red, green and blue spectral filters were combined to create this natural-color view. The image was taken with the Cassini spacecraft narrow-angle camera on May 29, 2017. The view was acquired at a distance of approximately 1.2 million miles (2 million kilometers) from Titan. Image scale is 5 miles (9 kilometers) per pixel.

The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. The Jet Propulsion Laboratory, a division of Caltech in Pasadena, manages the mission for NASA's Science Mission Directorate, Washington, D.C. 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, Colo.

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 https://ciclops.org.

Image Credit: NASA/JPL-Caltech/Space Science Institute

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Last Updated: Aug. 14, 2017
Editor: Martin Perez

[pkl]

Жить ему осталось месяц.  Эх! :oops:

[SashaBad]

Последние радарные изображения Титана сделанные Кассини.
 https://photojournal.jpl.nasa.gov/catalog/PIA21626
Во время своего последнего целевого пролета Титана, 22 апреля 2017 года,  Кассини  получил последние подробные изображения поверхности этого спутника.
На этом 127-м целевом пролёте Титана ( называемом «Т-126») радар использовался для получения двух изображений поверхности, показанных слева и справа  PIA21626.jpg (3.532 MB)  . Оба изображения имеют ширину около 200 миль (300 километров), сверху вниз. Объекты кажутся яркими, когда они наклонены к космическому аппарату или имеют грубые поверхности. Гладкие области выглядят темными.
Слева находятся те же яркие холмистые местности и более темные равнины, которые Кассини снял во время своего первого радарного прохода Титана в 2004 году. Ученые не видят очевидных изменений в этой местности, за 13 лет, с момента первоначального наблюдения.
Справа радар снова посмотрел на таинственный «волшебный остров» Титана ( PIA20021 ) в одном из крупных углеводородных морей, Ligeia Mare. Во время этого прохода не наблюдалось никакой «островной» активности. Ученые продолжают анализировать, что может быть причиной данного образования, выбирая из двух возможностей, волнами и пузырьками, .
В промежутке между двумя частями наблюдения за изображениями радиолокационный прибор переключился в режим альтиметрии, чтобы сделать первое измерение глубин некоторых озер, которые усеивают северную полярную область. Для измерений космический корабль направил антенну прямо на поверхность, и радар измерил задержку времени между эхо-сигналами от поверхности озер и дна.

На рисунке 1 показан график глубин, измеренных для восьми небольших озер в верхней части, совмещенных с радарным изображением той же области, что и предыдущий пролет Кассини Титана. Хотя эти данные все еще являются предварительными, все восемь озер, как полагают, имеют одинаковую глубину (около 100 метров, что составляет около 328 футов). Ученые еще не знают, связаны ли озера подземной системой, аналогичной уровню грунтовых вод или водоносного горизонта, но эта возможность поддаётся исследованию.

[sol]

pkl пишет:
Жить ему осталось месяц.    Эх!

И следующую мисиию хотя бы такого же рода многие из нас уже не увидят... Больно ползуче продвигаются проекты.
Хотя... может прорыв какой будет (вассимиры или еще чего такого пошустрей внедрят).

Та же грусть и про Уран с Нептуном. И вообще - кончина Кассини заставляет задуматься - что дальнего в ближайшие 20 лет реально долетит? Разве что Юпитерские темы...

[tnt22]

CassiniSaturn‏Подлинная учетная запись @CassiniSaturn 59 мин назад

The first of the final five dips into Saturn's atmosphere was successful: https://go.nasa.gov/2vFluKo  Full orbit guide: https://go.nasa.gov/2uHZScC 

[tnt22]

CassiniSaturn‏Подлинная учетная запись @CassiniSaturn 8 мин. назад

These unprocessed images were taken on Aug. 11 & 12. See more at: https://go.nasa.gov/2vcfmZR 

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[pkl]

sol пишет:

pkl пишет:
Жить ему осталось месяц.    Эх!

И следующую мисиию хотя бы такого же рода многие из нас уже не увидят... Больно ползуче продвигаются проекты.
Хотя... может прорыв какой будет (вассимиры или еще чего такого пошустрей внедрят).

Та же грусть и про Уран с Нептуном. И вообще - кончина Кассини заставляет задуматься - что дальнего в ближайшие 20 лет реально долетит? Разве что Юпитерские темы...

Многие? Да большинство. В ближайшие 20 лет - только миссии к Европе. И всё. В такие моменты начинаешь ошущать всю краткость своего существования.

Надо искать способ летать туда дёшево и быстро. Вот это и будет прорыв.

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ScienceCasts: Cassini's Grand Finale

ScienceAtNASA

Опубликовано: 15 авг. 2017 г.

Visit http://science.nasa.gov/ for more.

Cassini is in the process of executing 22 daring 'Grand Finale' dives in the 1,200-mile gap between Saturn and its innermost ring, concluding with an epic final plunge into the gas giant's upper atmosphere.

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https://spaceflightnow.com/2017/08/15/nasa-counts-down-final-month-of-cassinis-tour-of-saturn/

NASA counts down final month of Cassini's tour of Saturn
August 15, 2017 Stephen Clark

NASA's Cassini orbiter sailed through the tenuous outermost reaches of Saturn's atmosphere without trouble Monday, performing the first of five close swings nearer to the planet than any previous spacecraft before a final dive Sept. 15 to end the probe's nearly 20-year mission.

The plutonium-powered spacecraft made its closest brush to Saturn yet, close enough to require the activation of its chemical rocket thrusters to keep it stable.

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Artist's concept of the Cassini spacecraft during one the mission's five dives into the uppermost layers of Saturn's atmosphere before the mission ends Sept. 15. Credit: NASA/JPL-Caltech

Cassini typically uses spinning gyro-like wheels buried inside the spacecraft to control its orientation with momentum shifts, but engineers were not sure the wheels were strong enough to counteract aerodynamic forces as the orbiter plowed through Saturn's outer atmosphere.

The spacecraft came closest to Saturn at around 0422 GMT (12:22 a.m. EDT) Monday, and Cassini transmitted a radio signal nearly 24 hours later confirming it survived the flyby. NASA announced Tuesday that the first of five such dips into Saturn's atmosphere was successful.

Cassini had used its rocket thrusters during many of the craft's flybys of Saturn's largest moon Titan, which has its own dense atmosphere.

"Cassini's Titan flybys prepared us for these rapid passes through Saturn's upper atmosphere," said Earl Maize, Cassini project manager at NASA's Jet Propulsion Laboratory in Pasadena, California, before Monday's flyby. "Thanks to our past experience, the team is confident that we understand how the spacecraft will behave at the atmospheric densities our models predict."

The spacecraft will soar less than 1,100 miles (1,770 kilometers) above Saturn's cloud tops on each of its last five orbits, then spiral out beyond the rings to make successive egg-shaped loops around the planet.

Made mostly of hydrogen and helium, Saturn's atmosphere of golden haze sits above dense inner core scientists believe is made of rock and ice. One of the prime goals of Cassini's final months is to make measurements of Saturn's gravity and magnetic fields, data that could render an estimate of the core's size.


Cassini's on-board camera took this image of Saturn on Aug. 12. Credit: NASA/JPL-Caltech/Space Science Institute

Depending on the density of Saturn's atmosphere at Cassini's flyby altitude, ground controllers could command the probe to conduct "pop-up" or "pop-down" maneuvers to fly farther or closer to the planet on the next four dives.

Cassini's final close-up encounter with Titan on April 22 rerouted the spacecraft's orbit to pass between Saturn and its innermost ring, kicking off the mission's "grand finale" with 22 week-long circuits of the solar system's second-biggest planet.

Cassini's instruments were programmed to directly measure particles of Saturn's atmosphere during Monday's flyby.

"As it makes these five dips into Saturn, followed by its final plunge, Cassini will become the first Saturn atmospheric probe," said Linda Spilker, Cassini project scientist at JPL. "It's long been a goal in planetary exploration to send a dedicated probe into the atmosphere of Saturn, and we're laying the groundwork for future exploration with this first foray."

Scientists have concepts for a future dedicated probe to descend into Saturn's atmosphere to measure winds, density, and composition deep below the planet's cloud tops. Cassini will give researchers a taste.

Cassini's radar was expected to conduct sounding measurements to reveal the large-scale structure of Saturn's atmosphere in a region hidden fr om the view of conventional cameras.

"Its radar will peer deep into the atmosphere to reveal small-scale features as fine as 16 miles (25 kilometers) wide — nearly 100 times smaller than the spacecraft could observe prior to the grand finale," NASA said in a press release.

The final phase of Cassini's mission has already produced one surprising discovery. The space between Saturn and its rings is emptier than scientists expected, with Cassini detecting fewer impacts of tiny dust particles than predicted.

Cassini conducted its final orbit adjustment with its on-board thrusters July 15, and the spacecraft is now on a collision course with Saturn.


NASA's Cassini spacecraft looks toward the night side of Saturn's moon Titan in a view that highlights the extended, hazy nature of the moon's atmosphere. During its long mission at Saturn, Cassini has frequently observed Titan at viewing angles like this, wh ere the atmosphere is backlit by the Sun, in order to make visible the structure of the hazes. Cassini took this image May 29 with its narrow-angle camera. Credit: NASA/JPL-Caltech/Space Science Institute

A long-distance flyby of Titan on Sept. 11 will naturally nudge Cassini on a trajectory to fall into Saturn. The spacecraft will be crushed by Saturn's atmosphere and will burn up, with the final radio signal from Cassini expected to arrive on Earth around 8 a.m. EDT (1200 GMT; 5 a.m. PDT) on Sept. 15.

Running low on fuel, Cassini has explored Saturn and its moons for more than 13 years. The robotic explorer launched Oct. 15, 1997, from Cape Canaveral on top of a Titan 4 rocket, and entered orbit around Saturn on June 30, 2004, after a 2.2 billion-mile (3.5 billion-kilometer) interplanetary journey.

Cassini deployed the European Space Agency's Huygens lander for a descent to the surface of Titan in 2005.

Since its arrival, Cassini has circled Saturn almost 300 times, collected detailed imagery of Saturn's atmosphere and mysterious hexagonal polar vortex, explored its rings in minute detail, and observed 49 of Saturn's 62 known moons with close and long-range flybys.

Originally designed for a four-year tour of Saturn, the nearly $3.3 billion mission has far outlived its original lifetime, producing stunning imagery of the planet and documenting seasonal changes as the gaseous world completed almost half of one 29-year orbit around the sun.

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CassiniSaturn‏Подлинная учетная запись @CassiniSaturn 13 ч. назад

One highlight of our mission: searching the complexity of Saturn's rings and the processes operating within them https://go.nasa.gov/2vGgiU3

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https://saturn.jpl.nasa.gov/news/3089/nine-ways-cassini-matters-no-6/

Nine Ways Cassini Matters: No. 6

August 15, 2017

Cassini showed us the complexity of Saturn's rings and the dramatic processes operating within them.

Although Cassini scientists are still working on determining the exact origin of Saturn's main system of rings—and hope to collect data that will answer this question as its mission draws to a close—they have learned along the way that there are in fact, many ways to form rings around a planet.

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Long, sinuous, tendril-like structures seen in the vicinity of Saturn's icy moon Enceladus originate directly from geysers erupting from its surface, according to scientists studying images from NASA's Cassini spacecraft.

There is a diffuse ring that is created out of the bits of water ice jetted out by the moon Enceladus (the E ring). There are rings that were created because of the material thrown off when meteorites hit moons (such as the G ring and the two rings discovered by Cassini in images from 2006—the Janus-Epimetheus ring and the Pallene ring). There are rings controlled by interactions with moons, like the F ring, which is regularly perturbed by Prometheus, and the narrow ringlets that share the Encke Gap with Pan.

In addition to the rings' origins, Cassini's close-up examination has also revealed propeller-shaped features that mark the locations of hidden moonlets. The processes involved in the formation of such objects are thought to be similar to how planets form in disks around young stars.

Cassini also helped explain Saturn's "spokes," first spotted during the Voyager flybys of the early 1980s. Cassini scientists figured out that they are made of tiny ice particles that are lifted above the surface of the rings by an electrostatic charge, the way a statically-charged balloon held over a person's head will lift hairs. Their charge appears to be related to the angle of sunlight striking the rings—a seasonal effect.

The changing angle of the sun also showed scientists an array of vertical structures in the rings, including fluffy peaks of material as high as the Rocky Mountains at the outer edges of the A and B rings. The vertical structures and the shadows they cast also revealed wavy patterns in the parts of the rings that resemble a miniature Milky Way, giving scientists insight into the way galaxies form.

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CassiniSaturn‏Подлинная учетная запись @CassiniSaturn 5 ч назад

Today we began the second of the final five #GrandFinale orbits. Follow along: https://go.nasa.gov/2aNCy6t  Orbit guide: https://go.nasa.gov/2qcf2Vx