"Кассини" !

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CassiniSaturn‏Подлинная учетная запись @CassiniSaturn 28 мин. назад

An unprocessed image from May 4 shows the arc of #Saturn's G ring – about 104,080 miles (167,496km) from the planet. https://go.nasa.gov/2r2v5WB 

https://saturn.jpl.nasa.gov/news/3043/a-bright-arc-in-saturns-g-ring/

Feature | May 10, 2017

A Bright Arc in Saturn's G Ring

 

https://saturn.jpl.nasa.gov/system/video_items/229_PIA08327.m4v
A movie sequence of Saturn's G ring over a full orbital revolution captures its single bright arc on the ring's inner edge.
 
The arc in Saturn's G ring orbits at a distance of 104,080 miles (167,496 kilometers) from the planet. It is about 155 miles (250 kilometers) wide. The classical position of the G ring is about 107,250 miles (172,600 kilometers) from Saturn. Scientists suspect that bodies trapped in this remarkably bright feature, which includes the small moon Aegaeon, may be the source of the G ring material, driven outward from the arc by electromagnetic forces in the Saturn system.

The arc itself is likely held in place by gravitational resonances with Saturn's moon Mimas of the type that anchor the famed arcs in Neptune's rings.

In 2006, a movie sequenced Saturn's G ring over a full orbital revolution and captured its single bright arc on the ring's inner edge.

The images in this movie were taken on Sept. 19 and 20 at a distance of approximately 2.1 to 2.2 million kilometers (1.3 to 1.4 million miles) from Saturn and at a Sun-G ring-spacecraft, or phase, angle that ranged from 167 to 164 degrees. Image scale is about 13 kilometers (8 miles) per pixel in the radial (outward from Saturn) direction.

[zandr]

https://ria.ru/science/20170511/1494108458.html

"Кассини" увидел рои "пропеллеров" в кольцах Сатурна
© NASA/JPL-Caltech/Space Science Institute На этой фотографии можно увидеть пропеллеры в кольцах Сатурна (яркие небольшие линии)
МОСКВА, 11 мая — РИА Новости. Зонд "Кассини" получил самые детальные фотографии ближних колец Сатурна и увидел в них множество "пропеллеров" — ярких вихрей и волн, сообщает Лаборатория реактивного движения НАСА.
Кольца Сатурна, как сегодня считают ученые, возникли в результате разрушения "зародыша" планеты в первые дни существования Солнечной системы. Он подошел слишком близко к планете-гиганту, был разорван приливными силами и раздроблен на множество мелких осколков, самые плотные из которых были "съедены" Сатурном и Титаном, а остальные образовали материал будущих колец.
На новых снимках, полученных "Кассини" во время последнего "нырка" в кольца Сатурна, можно увидеть своеобразные "складки", "соломинки" и "пропеллеры", гуляющие по поверхности кольца А, ближнего к планете газопылевого диска, и его соседей. Об этих структурах ученые начали говорить еще в 2004 году при выходе "Кассини" на орбиту Сатурна, однако их первые фотографии были получены только зимой этого года, когда зонд начал пролетать через кольца. 
Как рассказывают ученые, новые фотографии позволяют прочертить линию между большими "пропеллерами", которые "Кассини" видел в начале своей миссии и которые связывают с существованием лун внутри газопылевых колец Сатурна, и небольшими структурами такого рода, найденными недавно. Их изучение поможет понять, как возникли эти луны, когда они родились и как долго они живут.

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Недавно "Кассини" официально начал заключительную фазу своей жизни, в последний раз встретившись с Титаном 22 апреля этого года. Сближение с этим спутником Сатурна помогло зонду поменять траекторию полета и выйти на курс столкновения с планетой, в атмосфере которой он сгорит в середине сентября этого года.
За это время "Кассини" совершит 22 пролета через промежуток между кольцами и их "властелином". Две недели назад он выполнил первый подобный пируэт, максимально тесно сблизившись с Сатурном и получив массу новых научных данных по устройству недр и атмосферы планеты-гиганта. Для дополнительной защиты зонда НАСА развернуло главную антенну "Кассини" таким образом, что она стала своеобразным заслоном и уберегла космический аппарат от ударов пылинок и микроастероидов.

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CassiniSaturn‏Подлинная учетная запись @CassiniSaturn 24 ч. назад

Our closest-ever image of the "propeller" in #Saturn's rings known informally as Bleriot. Details: https://go.nasa.gov/2pApupp 

https://saturn.jpl.nasa.gov/resources/7677/

Bleriot Propeller Close-up

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Photojournal: PIA21447

May 10, 2017

This view fr om 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.

This is the third and final propeller to be targeted for a close flyby observation during Cassini's ring-grazing orbits (the period fr om Nov. 2016 to April 2017 when Cassini's orbit passed just outside the main rings). Previously, Cassini targeted propellers Santos-Dumont (Cassini Targets a Propeller in Saturn's A Ring​) and Earhart ('Earhart' Propeller in Saturn's A Ring​). Because propellers are seen in the outermost parts of the main rings, the ring-grazing orbits provided Cassini's best opportunity to see them up close.

Спойлер

Many small, bright specks and linear, scratch-like artifacts are visible in the image. These artifacts are due to cosmic rays and particles of radiation near the planet striking the camera detector during the exposure.

Bleriot is the largest of the propellers in Saturn's rings. The wavy features embedded in the propeller structure indicate that its central moonlet is some 60 percent wider than that of Santos-Dumont, which means the Bleriot moonlet is about four times more massive.

Cassini scientists have been tracking the orbit of this object for the past decade, tracing the effect that the ring has upon it. Because it is the biggest propeller, it is more easily seen in lower-resolution images than other propellers, and thus it can be spotted in the most images by far. Here, as Cassini moved in close to the rings as part of its ring-grazing orbits, it was able to obtain this extreme close-up view of the propeller, which enables researchers to examine its effects on the ring as never before. These views, and others like them, will inform models and studies in new ways going forward.

Like one of the Santos-Dumont images in Cassini Targets a Propeller in Saturn's A Ring​, this image was taken on the unilluminated side of the rings, wh ere sunlight filters through the backlit ring. Like a frosted window, Saturn's rings look different depending on whether they are seen fully sunlit or backlit. On the lit side, the rings look darker where there is less material to reflect sunlight. On the unlit side, some regions look darker because there is less material, but other regions look dark because there is so much material that the ring becomes opaque.

Most dramatically in this image, a dark band cuts deeply through the middle of Bleriot's propeller.  It is much more prominent than the similar dark band in the unlit-side image of the Santos-Dumont propeller, indicating that Bleriot stirs up the ring particles to much higher densities than does Santos-Dumont. The dark bands are regions wh ere the density is so high that the ring becomes opaque to the sunlight filtering through the rings.

As in Cassini's other propeller close-up images, the central moonlet itself seems to be obscured by the stirred-up ring material around it, so that it cannot be directly seen. It would be about three pixels across, and lies at the center of the propeller structure.

The image was taken using the Cassini spacecraft's narrow-angle camera on April 12. Image scale in this view is 0.3 mile (500 meters) per pixel. The sun-ring-spacecraft angle, or phase angle, is 83 degrees.

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 Caltech in Pasadena, California, 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 http://saturn.jpl.nasa.gov and http://www.nasa.gov/cassini. The Cassini imaging team homepage is at http://ciclops.org.

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Credit

NASA/JPL-Caltech/Space Science Institute

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CassiniSaturn‏Подлинная учетная запись @CassiniSaturn 24 ч. назад

It's a whole swarm of propellers! Learn more: https://go.nasa.gov/2pzWU7G 

https://saturn.jpl.nasa.gov/resources/7678/

Propeller Belts of Saturn

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Photojournal: PIA21447

May 10, 2017

This view from NASA's Cassini spacecraft is the sharpest ever taken of belts of the features called propellers in the middle part of Saturn's A ring.

The propellers are the small, bright features that look like double dashes, visible on both sides of the wave pattern that crosses the image diagonally from top to bottom.

The original discovery of propellers in this region in Saturn's rings (see Four Propellers, Propeller Motion​, Locating the Propellers​) was made using several images taken from very close to the rings during Cassini's 2004 arrival at Saturn. Those discovery images were of low resolution and were difficult to interpret, and there were few clues as to how the small propellers seen in those images were related to the larger propellers Cassini observed later in the mission (for example 'Earhart' Propeller in Saturn's A Ring, Cassini Targets a Propeller in Saturn's A Ring​, and Bleriot Propeller Close-up​).

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This image, for the first time, shows swarms of propellers of a wide range of sizes, putting the ones Cassini observed in its Saturn arrival images in context. Scientists will use this information to derive a "particle size distribution" for propeller moons, which is an important clue to their origins. 

This region was also featured in PIA21059.

The image was taken using the Cassini spacecraft's narrow-angle camera on April 19. The view was has an image scale of 0.24 mile (385 meters) per pixel, and was taken at a sun-ring-spacecraft angle, or phase angle, of 108 degrees. The view looks toward a point approximately 80,000 miles (129,000 kilometers) from Saturn's center.

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 Caltech in Pasadena, California, 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 http://saturn.jpl.nasa.gov and http://www.nasa.gov/cassini. The Cassini imaging team homepage is at http://ciclops.org.

Downloads

Original (TIFF)
1 MB
image/tiff

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Original (JPG)
901 KB
image/jpeg

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Credit

NASA/JPL-Caltech/Space Science Institute

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CassiniSaturn‏Подлинная учетная запись @CassiniSaturn 6 ч. назад

Right now we're about 754K miles from #Saturn and going about 47,000 mph (relative to Earth). Join us! #GrandFinale https://go.nasa.gov/2n1HGqv 

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CassiniSaturn‏Подлинная учетная запись @CassiniSaturn 12 мая

We're at apoapse RIGHT NOW, the farthest from #Saturn we'll get in this #GrandFinale orbit. We're turning back for ring dive No. 4 (May 15).

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

IN PROGRESS: Orbit 274 - May 12 - 18[TH]Event[/TH][TH]Date[/TH][TH]Spacecraft Time (UTC)[/TH][TH]Local Time (PDT)[/TH][TH]Notes[/TH]

Apoapse	May 12	11:30 a.m.	4:30 a.m.
Ring Crossing #4	May 15	4:42 p.m.	9:42 a.m.
Downlink	May 15	4:42 p.m.	9:42 a.m.	Cassini will be communicating with Earth during the crossing. Estimated Earth Received Time (ERT) is 9:42 a.m. PDT on May 15.

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• During this Grand Finale orbit, Cassini's visible-light camera, the Imaging Science Subsystem (ISS), observes Saturn's most prominent ring propeller features.
• Next, the Radio Science Subsystem (RSS) takes advantage of one of the best opportunities in the mission to conduct radio occultations of Saturn's ring system and run a gravity experiment to study Saturn's gravitational field with unprecedented detail. The experiment aims to discover how spherical Saturn's gravity field is, which helps scientists measure the mass of Saturn's rings, a figure that is not precisely known.
• During the radio science/gravity observations, the spacecraft's Cosmic Dust Analyzer (CDA) scoops up and analyzes small ring particles to help determine the age of Saturn's rings. Interplanetary meteoroids bombard Saturn's main rings, depositing silicates, organics, and metals in the ring particles. The more of those contaminants the CDA finds, the older Saturn's rings probably are.
• During this orbit, Cassini gets within 1,650 miles (2,660 kilometers) of Saturn's 1-bar level. Cassini also passes within 3,110 miles (5,000 kilometers) of the inner edge of Saturn's D ring.
  

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NASA‏Подлинная учетная запись @NASA 12 мин. назад

Saturn's shadow on the rings grows shorter as the northern hemisphere advances toward summer. Get the details: http://go.nasa.gov/2rjvp3m 

https://www.nasa.gov/image-feature/jpl/pia21328/short-shadow

May 15, 2017

Short Shadow

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The projection of Saturn's shadow on the rings grows shorter as Saturn's season advances toward northern summer, thanks to the planet's permanent tilt as it orbits the sun. This will continue until Saturn's solstice in May 2017. At that point in time, the shadow will extend only as far as the innermost A ring, leaving the middle and outer A ring completely free of the planet's shadow.

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Over the course of the Cassini mission, the shadow of Saturn first lengthened steadily until equinox in August 2009. Since then, the shadow has been shrinking. These changes can be seen by comparing the shadow in the above view to its appearance as Cassini approached Saturn in 2004 (PIA06077), equinox in 2009 (PIA11667), and two years ago, in 2015 (PIA20498).

This view looks toward the sunlit side of the rings from about 10 degrees above the ring plane. The image was taken in visible light with the Cassini spacecraft wide-angle camera on Feb. 3, 2017.

The view was acquired at a distance of approximately 760,000 miles (1.2 million kilometers) from Saturn. Image scale is 46 miles (73 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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Last Updated: May 15, 2017
Editor: Tony Greicius

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CassiniSaturn‏Подлинная учетная запись @CassiniSaturn 32 мин. назад

Nominal after #GrandFinale ring dive No. 4: We're safely through the gap between #Saturn and its rings. https://go.nasa.gov/1Up1oba 

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CassiniSaturn‏Подлинная учетная запись @CassiniSaturn 10 мин. назад

During this #GrandFinale orbit we made gravity observations to help measure the mass of #Saturn's rings. https://go.nasa.gov/2qcf2Vx 

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CassiniSaturn‏Подлинная учетная запись @CassiniSaturn 12 ч. назад

We're ~750K miles (1.2 million km) from #Saturn's cloud tops and turning back for #GrandFinale dive No. 5 (May 21). https://go.nasa.gov/2qcf2Vx

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http://actualnews.org/exclusive/172829-uchenye-obnaruzhili-priznaki-togo-chto-encelad-mozhet-byt-prigoden-dlya-zhizni.html

Ученые обнаружили признаки того, что Энцелад может быть пригоден для жизни
NASA накануне уведомило, что миссия космического аппарата "Кассини" к Сатурну собрала очередные доказательства того, что есть химические реакции, происходящие под ледяной поверхностью Энцелада, которые могли бы обеспечить условия для жизни. Сообщение об этом публикует издание NPR.

Ученые считают, что, поскольку Энцелад является относительно молодым объектом, то, возможно, еще не пришло время для возникновения жизни. В 2015 году ученые обнаружили свидетельства теплого океана непосредственно под поверхностью спутника. Это фактически являло интересную перспективу - эксперты задавались вопросом, способен ли этот теплый океан "сотрудничать" с породами, чтобы образовать форму химической энергии, которая могла бы быть задействована некоторыми формами жизни. Если это правда, то возможно создание организмов как на Земле, которые питаются энергией, содержащейся в глубоководных океанских жерлах.
Недавно ученые NASA сообщили, что они выявили доказательства того, что вышеупомянутая химическая реакция, вероятно, наблюдается непосредственно под поверхностью Энцелада. Пролетев сквозь струйку пыли из его ледяной раковины, "Кассини" смог выявить молекулярный водород. Присутствие последнего в подповерхностном океане, в свою очередь, означает, что микробы, если таковые имеются, могли привлечь его для получения энергии посредством объединения водорода с двуокисью углерода, которая растворена в воде. Названная метаногенезом, это реакция, которая находится в основе жизни на Земле.
Однако некоторые эксперты считают, что высокие уровни водорода, напротив, делают менее вероятным возникновение жизни на спутнике Сатурна. При этом они полагают, что у луны Юпитера - Европы больше шансов на появление жизни, поскольку она намного старше Энцелада.    
Автор: Марину Вебер

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CassiniSaturn‏Подлинная учетная запись @CassiniSaturn 2 ч. назад

The low angle of sunlight along the crescent of #Saturn's moon Enceladus highlights the furrows on its icy surface https://go.nasa.gov/2r9BgLI 

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https://saturn.jpl.nasa.gov/resources/7682/

Slim Crescent of Ice


 
Photojournal: PIA21330

May 22, 2017

The low angle of sunlight along the slim crescent of Saturn's moon Enceladus (313 miles or 504 kilometers across) highlights the many fractures and furrows on its icy surface.

This view looks toward the Saturn-facing hemisphere of Enceladus, which is dimly illuminated in the image above by sunlight reflected off Saturn. North on Enceladus is up and rotated 14 degrees to the left. The image was taken in visible light with the Cassini spacecraft narrow-angle camera on Dec. 26, 2016.

The view was obtained at a distance of approximately 104,000 miles (168,000 kilometers) from Enceladus. Image scale is 3,303 feet (1 kilometer) 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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CassiniSaturn‏Подлинная учетная запись @CassiniSaturn 2 ч. назад

Once more through the gap – we've successfully completed the fifth dive between #Saturn and its rings http://go.nasa.gov/2qcf2Vx 

Orbit_05

CURRENT ORBIT - May 18 - 25[TH]Event[/TH][TH]Date[/TH][TH]Spacecraft Time (UTC)[/TH][TH]Local Time (PDT)[/TH][TH]Notes[/TH]

Apoapse	May 18	9:59 p.m..	2:59 p.m.
Ring Crossing #5	May 22	3:11 a.m.	8:11 p.m. (May 21)
Downlink	May 22	3:11 a.m.	8:11 p.m. (May 21)	Cassini will be communicating with Earth during the ring crossing. Estimated Earth Received Time (ERT) is 9:26 p.m. PDT on May 21.

[/li]
• This orbit, like the previous one, is one of the best opportunities in the mission for the Radio Science Subsystem (RSS) to conduct radio occultations of Saturn's ring system and run a gravity experiment to study Saturn's gravitational field with unprecedented detail. The experiment helps clarify how spherical Saturn's gravity field is, but also helps scientists measure the mass of Saturn's rings, a figure that is not precisely known.
• And as with the previous orbit, the spacecraft's Cosmic Dust Analyzer (CDA) scoops up and analyzes ring particles — this time larger ring particles rather than the relatively small particles — to help determine the age of Saturn's rings. Interplanetary meteoroids bombard Saturn's main rings, depositing silicates, organics, and metals in the ring particles. The more of those contaminants the CDA finds, the older Saturn's rings probably are.
• Also on this orbit, the spacecraft's Imaging Science Subsystem (ISS), Composite Infrared Spectrometer (CIRS), and Visible and Infrared Mapping Spectrometer (VIMS) observe and map Saturn's atmosphere, studying the different temperatures of the atmospheric layers, as well as the atmosphere's composition.
• During this orbit, Cassini gets within 1,680 miles (2,700 kilometers) of Saturn's 1-bar level. Cassini also passes within 3,120 miles (5,010 kilometers) of the inner edge of Saturn's D ring.
  

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https://spaceflightnow.com/2017/05/22/nasas-cassini-spacecraft-aims-to-skirt-saturns-innermost-ring/

NASA's Cassini spacecraft aims to skirt Saturn's innermost ring

May 22, 2017 Stephen Clark

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Cassini took this image of Saturn and its rings May 13. Credit: NASA/JPL-Caltech/Space Science Institute

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Fresh off its fifth passage through a gap between Saturn's atmosphere and rings, NASA's robotic Cassini spacecraft is looping toward a close brush with the planet's innermost ring next week, when the probe will again use its high-gain antenna as a shield against icy particles that may lie in its path.

Cassini made another safe trip through the 1,500-mile (2,400-kilometer) space between Saturn and its rings at 0311 GMT Monday (11:11 p.m. EDT Sunday), according to NASA, marking the fifth time the craft has dived through the previously-unexplored region since late April.

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During its latest ring passage, the orbiter's instruments were expected to measure Saturn's gravitational field and gather data on the mass of the planet's rings. Cassini's Cosmic Dust Analyzer instrument was also supposed to collect and analyze ring particles on this week's flyby.

"Interplanetary meteoroids bombard Saturn's main rings, depositing silicates, organics, and metals in the ring particles," scientists wrote in a description of this week's flight through the ring gap. "The more of those contaminants the CDA (Cosmic Dust Analyzer) finds, the older Saturn's rings probably are."

NASA tweeted from Cassini's account Monday that the flyby was successful.


This diagram created by Cassini mission planners illustrates the close approaches of the spacecraft during its Grand Finale orbits between Saturn's innermost (D) ring and the giant planet's atmosphere. Credit: NASA/JPL-Caltech/Erick Sturm

The plutonium-powered spacecraft is in its final months, with its orbit around Saturn now taking it on weekly plunges through the ring gap.

Data recorded during the close-up flybys will help tell scientists the age of Saturn's rings, which will indicate their likely origin. More measurements of the rings' mass and Saturn's magnetic field, atmosphere and internal structure are also on tap during Cassini's final months.

The orbiter is heading for a Sept. 15 plunge into Saturn's atmosphere, a guided dive during which Cassini will be crushed and vaporized. The craft is running low on fuel, and officials want to ensure the probe is destroyed before losing control of it.

Scientists worry that Cassini could eventually collide with one of Saturn's habitable moons, such as Titan or Enceladus, and spoil future discoveries.

Cassini's next journey through the ring gap is set for 1422 GMT (10:22 a.m. EDT) Sunday, May 28, when the spacecraft will make its closest brush with the inner edge of Saturn's D ring, a belt of tiny ice particles encircling the planet.


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

Ground controllers will command the spacecraft to point its dish-shaped antenna in its direction of travel during Sunday's approach as a safeguard against potentially damaging impacts from ring particles. So far, scientists have detected fewer strikes from icy debris in the ring gap than predicted, allowing engineers to forego using the antenna as a shield during the last four flybys.

Cautious managers directed the antenna to point forward — in its so-called "ram" position — during Cassini's first flight through the ring gap last month.

Objectives during Sunday's flyby include unprecedented radar observations of the structure of Saturn's rings, up-close imaging of the rings, and listening for particle impacts with one of Cassini's science instruments.

Because the high-gain antenna will not be aimed at Earth, Cassini will be out of contact with mission control during Sunday's encounter. The craft is scheduled to radio its status back to Earth around 0329 GMT Monday, May 29 (11:29 p.m. EDT Sunday).

Cassini will come close to Saturn's D ring on three more occasions in June and July, when it will again use its antenna for protection.

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[tnt22]

CassiniSaturn‏Подлинная учетная запись @CassiniSaturn 4 ч. назад

Solstice arrives at #Saturn today, and we have a ringside seat: https://go.nasa.gov/2rRIQYv

https://www.jpl.nasa.gov/news/news.php?feature=6855

May 24, 2017

[SIZE=8]Cassini Looks on as Solstice Arrives at Saturn[/SIZE]


These natural color views fr om Cassini show how the color of Saturn's north-polar region changed between June 2013 and April 2017, as the northern hemisphere headed toward summer solstice. Image credit: NASA/JPL-Caltech/SSI/Hampton Univ.
› Full image and caption

NASA's Cassini spacecraft still has a few months to go before it completes its mission in September, but the veteran Saturn explorer reaches a new milestone today. Saturn's solstice -- that is, the longest day of summer in the northern hemisphere and the shortest day of winter in the southern hemisphere -- arrives today for the planet and its moons. The Saturnian solstice occurs about every 15 Earth years as the planet and its entourage slowly orbit the sun, with the north and south hemispheres alternating their roles as the summer and winter poles.

Reaching the solstice, and observing seasonal changes in the Saturn system along the way, was a primary goal of Cassini's Solstice Mission -- the name of Cassini's second extended mission.

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Cassini arrived at Saturn in 2004 for its four-year primary mission to study Saturn and its rings and moons. Cassini's first extended mission, from 2008 to 2010, was known as the Equinox Mission. During that phase of the mission, Cassini watched as sunlight struck Saturn's rings edge-on, casting shadows that revealed dramatic new ring structures. NASA chose to grant the spacecraft an additional seven-year tour, the Solstice Mission, which began in 2010.

"During Cassini's Solstice Mission, we have witnessed -- up close for the first time -- an entire season at Saturn," said Linda Spilker, Cassini project scientist at NASA's Jet Propulsion Laboratory, Pasadena, California. "The Saturn system undergoes dramatic transitions from winter to summer, and thanks to Cassini, we had a ringside seat."

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Saturn

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During its Solstice Mission, Cassini watched a giant storm erupt and encircle the planet. The spacecraft also saw the disappearance of bluer hues that had lingered in the far north as springtime hazes began to form there. The hazes are part of the reason why features in Saturn's atmosphere are more muted in their appearance than those on Jupiter.

Data from the mission showed how the formation of Saturn's hazes is related to the seasonally changing temperatures and chemical composition of Saturn's upper atmosphere. Cassini researchers have found that some of the trace hydrocarbon compounds there -- gases like ethane, propane and acetylene -- react more quickly than others to the changing amount of sunlight over the course of Saturn's year.

Researchers were also surprised that the changes Cassini observed on Saturn didn't occur gradually. They saw changes occur suddenly, at specific latitudes in Saturn's banded atmosphere. "Eventually a whole hemisphere undergoes change, but it gets there by these jumps at specific latitude bands at different times in the season," said Robert West, a Cassini imaging team member at JPL.

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Rings

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Following equinox and continuing toward northern summer solstice, the sun rose ever higher above the rings' northern face. And as the sun rises higher, its light penetrates deeper into the rings, heating them to the warmest temperatures seen there during the mission. The solstice sunlight helps reveal to Cassini's instruments how particles clump together and whether the particles buried in the middle of the ring plane have a different composition or structure than the ones in the rings' outer layers.

Saturn's changing angle with respect to the sun also means the rings are tipped toward Earth by their maximum amount at solstice. In this geometry, Cassini's radio signal passes more easily and cleanly through the densest rings, providing even higher-quality data about the ring particles there.

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Titan

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Cassini has watched Saturn's largest moon, Titan, change with the seasons, with occasional dramatic outbursts of cloud activity. After observing methane storm clouds around Titan's south pole in 2004, Cassini watched giant storms transition to Titan's equator in 2010. Although a few northern clouds have begun to appear, scientists have since been surprised at how long it has taken for cloud activity to shift to the northern hemisphere, defying climate models that had predicted such activity should have started several years earlier.

"Observations of how the locations of cloud activity change and how long such changes take give us important information about the workings of Titan's atmosphere and also its surface, as rainfall and wind patterns change with the seasons too," said Elizabeth Turtle, a Cassini imaging team associate at the Johns Hopkins University Applied Physics Laboratory in Laurel, Maryland.

In 2013, Cassini observed a sudden and rapid buildup of haze and trace hydrocarbons in the south that were previously observed only in Titan's high north. This indicated to scientists that a seasonal reversal was underway, in which Titan's main atmospheric circulation changes direction. This circulation was apparently channeling fresh hydrocarbon chemicals from closer to the equator toward the south pole, wh ere they were safe from destruction by sunlight as that pole moved deeper into winter shadow.

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Enceladus

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For Enceladus, the most important seasonal change was the onset of winter darkness in the south. Although it meant Cassini could no longer take sunlit images of the geologically active surface, the spacecraft could more clearly observe the heat coming from within Enceladus itself. With the icy moon's south pole in shadow, Cassini scientists have been able to monitor the temperature of the terrain there without concern for the sun's influence. These observations are helping researchers to better understand the global ocean that lies beneath the surface. From the moon's south polar region, that hidden ocean sprays a towering plume of ice and vapor into space that Cassini has directly sampled.

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Toward the Final Milestone

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As Saturn's solstice arrives, Cassini is currently in the final phase of its long mission, called its Grand Finale. Over the course of 22 weeks from April 26 to Sept. 15, the spacecraft is making a series of dramatic dives between the planet and its icy rings. The mission is returning new insights about the interior of the planet and the origins of the rings, along with images from closer to Saturn than ever before. The mission will end with a final plunge into Saturn's atmosphere on Sept. 15.

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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, California, 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.
818-394-7013
preston.dyches@jpl.nasa.gov

2017-150

[zandr]

https://ria.ru/science/20170525/1495046654.html

"Кассини" получил фотографии Сатурна в день солнцестояния
Шестиугольный ураган на северном полюсе Сатурна в 2013 и 2017 годах
© Фото : NASA/JPL-Caltech/Space Science Institute/Hampton University
МОСКВА, 25 мая – РИА Новости. Зонд "Кассини" получил новые фотографии Сатурна и знаменитого шестиугольного урагана на его северном полюсе во второй день солнцестояния на планете-гиганте, свидетелем которого он смог стать за 13 лет работы на ее орбите, сообщает НАСА.
"Во время второй фазы миссии "Кассини", которая называлась "Солнцестоянием", нам удалось проследить за полной сменой всех сезонов на Сатурне. Вся система резко меняется при наступлении лета и завершении зимы, и благодаря "Кассини", у нас была великолепная возможность проследить за всем этим", — заявила Линда Спилкер (Linda Spilker), научный руководитель миссии.
Недавно "Кассини" официально начал заключительную фазу в своей жизни, в последний раз встретившись с Титаном 22 апреля этого года. Сближение с этим спутником Сатурна помогло зонду поменять траекторию полета и выйти на курс столкновения с планетой-гигантом, в атмосфере которой он сгорит в середине сентября этого года, совершив 22 пролета через промежуток между кольцами и их "властелином".
До этого, Кассини" работал более семи лет в рамках продленной миссии, получившей официальное имя "Солнцестояние" в 2010 году. Благодаря этому ученым удалось проследить за наступлением зимы и лета на планете-гиганта, и проследить за всем изменениями климата на поверхности Титана при смене сезонов на Сатурне.

© Фото : NASA/JPL/Space Science Institute
Сатурн, наполовину подсвеченный Солнцем в день солнцестояния
Многие из этих вещей, как рассказывает Спилкер, мы никогда бы не увидели, если бы НАСА не приняло решение продлить миссию. К примеру, пять лет назад "Кассини" впервые увидел, как атмосферу Сатурна заволок гигантский ураган при наступлении осени, а в его атмосфере появилась дымка из углеводородов.
Кроме того, зонду удалось увидеть, как солнечный свет проникает через кольца Сатурна, проследить за миграциями зимних штормов на Титане, постоянно "переезжающих" из северного полушария в южное и в обратном направлении при наступлении зимы и лета на самом землеподобном спутнике планеты-гиганта.
Главным же открытием "Кассини" за этот период стало обнаружение того, что гейзеры Энцелада выбрасывают горячую воду, в принципе пригодную для зарождения и поддержания жизни. Это открытие уже заставило НАСА задуматься об отправке еще одной миссии к Сатурну и Энцеладу.

[Maks]

получается, что из водяного льда колец Сатурна, Юпитера, Урана можно добывать водород - ракетное топливо и кислород!
Можно сделать там базу роботов, оранжерею, где выращивать овощи и фрукты.

[tnt22]

CassiniSaturn‏Подлинная учетная запись @CassiniSaturn 20 мин. назад

Gap cleared: we've completed our sixth dive between #Saturn & the rings, as simulated here in @NASA_Eyes. Details: https://go.nasa.gov/1Up1oba

https://twitter.com/i/videos/tweet/868929079768104960

[tnt22]

CassiniSaturn‏Подлинная учетная запись @CassiniSaturn 3 ч. назад

Before we entered our final orbits, we acquired unprecedented views of #Saturn's intricate ring system. More: https://go.nasa.gov/2sdPmrP 

https://saturn.jpl.nasa.gov/resources/7684/

Waving Goodbye

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Photojournal: PIA21329

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May 29, 2017

Before Cassini entered its Grand Finale orbits, it acquired unprecedented views of the outer edges of the main ring system. For example, this close-up view of the Keeler Gap, which is near the outer edge of Saturn's main rings, shows in great detail just how much the moon Daphnis affects the edges of the gap.

This image was part of a mosaic that included Daphnis (The Realm of Daphnis).

Daphnis creates waves in the edges of the gap through its gravitational influence. Some clumping of ring particles can be seen in the perturbed edge, similar to what was seen on the edges of the Encke Gap back when Cassini arrived at Saturn in 2004.

This view looks toward the sunlit side of the rings from about 3 degrees above the ring plane. The view was acquired at a distance of approximately 18,000 miles (30,000 kilometers) from Daphnis and at a Sun-Daphnis-spacecraft, or phase, angle of 69 degrees. Image scale is 581 feet (177 meters) per pixel. The image was taken in visible light with the Cassini spacecraft narrow-angle camera on Jan. 16, 2017.

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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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