"Кассини" !

[sol]

альпинизм в условиях малой гравитации - ОЧЕНЬ опасная вещь. Потому как перепрыгнув булыжник 5 метров в высоту на другой стороне может оказаться 10 км трещина - вполне достаточная высот сломать колени и проткнуть костью скафандр.

Ну так альпинизм всегда опасен. На Земле он куда опаснее.

Позволю себе не согласиться!

На Луне альпинизм куда опаснее. Во первых - моторика человека (в т.ч. опытного альпиниста) заточена на нагрузки в условиях земной гравитации. В условиях пониженой человек будет "перебирать" необходимое усилие, или ощущая все легким и безвредным - недооценивать препятствие. Что приведет к срывам, допустим, в пропасть. А на Луне свалиться с 600 м все равно как на Земле - со 100.

На Весте тоже грохнуться можно, это вам не Итокава.

Безопасным для занятий альпинизмом можно считать астероид с первой космической, равной скорости прыжка со второго этажа на Земле. И то, если не учитывать центобежных ньюансов при неровностях рельефа (можно получить по радикулиту вершиной горы с другого полушария)

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http://www.unmannedspaceflight.com/index.php?showtopic=7005&view=findpost&p=178983

15-frame animated GIF showing Dione rotating. From raw images taken on October 1, 2011

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NASA's Cassini Makes a New Pass at Enceladus
November 03, 2011

NASA's Cassini spacecraft will acquire the first detailed radar images of Saturn's moon Enceladus during a flyby on Sunday, Nov. 6. These will be the first high-resolution radar observations made of an icy moon other than Titan. The results will provide new information about the surface of Enceladus and enable researchers to compare its geological features as seen by radar with those of Titan.

The spacecraft will fly past Enceladus at a distance of about 300 miles (500 kilometers) at its closest point. During the encounter, Cassini's synthetic aperture radar will sweep across a long, narrow swath of the surface just north of the moon's south pole. Cassini will use other radar techniques to map much more of the surface of Enceladus at lower resolutions and determine some of the surface's physical properties as the spacecraft approaches and then speeds away from the icy body.

During this flyby, the mission's visible-light cameras will take images of Enceladus and its famous jets, and the composite infrared spectrometer will make new measurements of hot spots from which the jets emerge. Cassini's ultraviolet imaging spectrograph will also make distant observations of Saturn's moon Dione and its environment.

http://www.jpl.nasa.gov/news/news.cfm?release=2011-340

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Комки в кольцах Сатурна застали за игрой в "хищника-жертву"

Астрофизики описали поведение "комков" на кольцах Сатурна. Статья исследователей появилась в журнале Icarus.

Комки, о которых идет речь в работе, были обнаружены зондом "Кассини" на кольцах F и B. Анализ их динамики почти сразу позволил установить, что они возникают под действием гравитации близлежащих спутников - Прометея и Мимаса соответственно. До последнего времени, однако, динамика формирования (и, как предполагалось, последующего разрушения) этих объектов была изучена слабо.

В рамках новой работы ученые применили к изучению комков так называемую модель "хищник-жертва", известную также как система Лотки - Вольтерра. Это система нелинейных дифференциальных уравнений, которая описывает изменение популяции хищников и их жертв (например, зайцев и лис) в простейшей экосистеме.

Ученые установили, что комки растут со временем - чем он больше, тем быстрее вокруг него движутся частицы кольца. Начиная с порогового значения в один километр, это приводит к разрушению объекта и замедлению частиц. Как следствие, процесс после этого снова повторяется. Ученые полагают, что комки могут приводить к появлению более устойчивых образований.

Сатурн является не единственной планетой в Солнечной системе, у которой есть кольца. Аналогичные образования (только менее заметные) были обнаружены еще у Юпитера, Урана и Нептуна. Также, в августе 2011 года в Astronomy and Astrophysics была подана статья, в которой описывалась возможность наличия аналогичных колец у Плутона.

http://www.lenta.ru/news/2011/11/15/rings/
http://www.sciencedirect.com/science/article/pii/S0019103511003812

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Cassini Chronicles the Life and Times of Saturn's Giant Storm

New images and animated movies from NASA's Cassini spacecraft chronicle the birth and evolution of the colossal storm that ravaged the northern face of Saturn for nearly a year.

These new full-color mosaics and animations show the storm from its emergence as a tiny spot in a single image almost one year ago, on Dec. 5, 2010, through its subsequent growth into a storm so large it completely encircled the planet by late January 2011.

The monster tempest, which extended north-south approximately 9,000 miles (15,000 kilometers), is the largest seen on Saturn in the past two decades and is the largest by far ever observed on the planet from an interplanetary spacecraft. On the same day that Cassini's high-resolution cameras captured the first images of the storm, Cassini's radio and plasma wave instrument detected the storm's electrical activity, revealing it to be a convective thunderstorm. The storm's active convecting phase ended in late June, but the turbulent clouds it created linger in the atmosphere today.

The storm's 200-day active period also makes it the longest-lasting planet-encircling storm ever seen on Saturn. The previous record holder was an outburst sighted in 1903, which lingered for 150 days. The large disturbance imaged 21 years ago by NASA's Hubble Space Telescope and comparable in size to the current storm lasted for only 55 days.

The collected images and movies from Cassini's imaging team can be seen at http://www.nasa.gov/cassini and http://saturn.jpl.nasa.gov and http://ciclops.org . They include mosaics of dozens of images stitched together and presented in true and false colors.

"The Saturn storm is more like a volcano than a terrestrial weather system," said Andrew Ingersoll, a Cassini imaging team member at the California Institute of Technology in Pasadena. "The pressure builds up for many years before the storm erupts. The mystery is that there's no rock to resist the pressure – to delay the eruption for so many years."

Cassini has taken hundreds of images of this storm as part of the imaging team's "Saturn Storm Watch" campaign. During this effort, Cassini takes quick looks at the storm in between other scheduled observations of either Saturn or its rings and moons. The new images, together with other high-quality images collected by Cassini since 2004, allow scientists to trace back the subtle changes on the planet that preceded the storm's formation and have revealed insights into the storm's development, its wind speeds and the altitudes at which its changes occur.

The storm first appeared at approximately 35 degrees north latitude on Saturn and eventually wrapped itself around the entire planet to cover approximately 2 billion square miles (5 billion square kilometers). The biggest disturbance Cassini had previously witnessed on Saturn occurred in a latitude band in the southern hemisphere called "Storm Alley" because of the prevalence of thunderstorms in this region. That storm lasted several months, from 2009 into 2010. That disturbance was actually a cluster of thunderstorms, each of which lasted up to five days or so and affected only the local weather. The recent northern disturbance is a single thunderstorm that raged continuously for more than 200 days and impacted almost one-fifth of the entire northern hemisphere.

"This new storm is a completely different kind of beast compared to anything we saw on Saturn previously with Cassini," said Kunio Sayanagi, a Cassini imaging team associate and planetary scientist at the University of California, Los Angeles. "The fact that such outbursts are episodic and keep happening on Saturn every 20 to 30 years or so is telling us something about deep inside the planet, but we have yet to figure out what it is."

Current plans to continue the mission through 2017 will provide opportunities for Cassini to witness further changes in the planet's atmosphere as the seasons progress to northern summer.

"It is the capability of being in orbit and able to turn a scrutinizing eye wherever it is needed that has allowed us to monitor this extraordinary phenomenon," said Carolyn Porco, Cassini imaging team leader at the Space Science Institute in Boulder, Colo. "Seven years of taking advantage of such opportunities have already made Cassini one of the most scientifically productive planetary missions ever flown."

http://www.nasa.gov/mission_pages/cassini/whycassini/cassini20111117.html

[mefisto_x]

Никто не подскажет какова скорость передачи данных с Кассини? А то искал не мог найти эту информацию

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http://irg.cs.ohiou.edu/ocp/papers/priority-paradigm.pdf
http://www.tp.umu.se/space/Proj_05/Daniel.W.pdf
http://descanso.jpl.nasa.gov/DPSummary/Descanso3--Cassini2.pdf

Let us consider the Cassini spacecraft (Figure 1) for example. The Cassini-
Huygens mission carries 18 science instruments in total - 12 on the Cassini
orbiter and 6 on the Huygens probe to Titan. The science instruments on board
Cassini and their estimated data rates [13] are shown in Table 1.
Cassini operates in the X-band (7-12 GHz) radio channel with a downlink
data bandwidth (while using its High-Gain Antenna) in the range of 14.2 to
165.9 Kbps, signi
cantly lesser than the total bandwidth required to support all
the instruments data simultaneously. It is conceivable that based on the science
experimental results, data from the instruments could be of varying degrees of
interest and importance during various times in the mission. For example, the
Cosmic Dust Analyzer might have an interesting experimental observation that
may be of more immediate critical value compared to the last image captured
by the wide-angle camera of the Imaging Science Subsystem (which presumably
may be stored and transmitted in the next communication window).

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What's That Sparkle in Cassini's Eye?



NASA's Cassini spacecraft obtained these views of the south polar area of Saturn's moon Enceladus in visible and near-visible (ultraviolet and infrared) light and synthetic-aperture radar (SAR).

http://www.nasa.gov/mission_pages/cassini/multimedia/pia15172.html

http://www.nasa.gov/multimedia/videogallery/index.html?media_id=122777581

December 01, 2011

The moon Enceladus, one of the jewels of the Saturn system, sparkles peculiarly bright in new images obtained by NASA's Cassini spacecraft. The images of the moon, the first ever taken of Enceladus with Cassini's synthetic aperture radar, reveal new details of some of the grooves in the moon's south polar region and unexpected textures in the ice. These images, obtained on Nov. 6, 2011, are the highest-resolution images of this region obtained so far.

The area on Enceladus observed by Cassini's radar instrument does not include the famous "tiger stripes," fissures that eject great plumes of ice particles and water vapor, but covers regions just a few hundred miles away from the stripes. Scientists are scrutinizing an area around 63 degrees south latitude and 51 degrees west longitude that appears to be very rough, a texture that shows up as very bright in the radar images.

"It's puzzling why this is some of the brightest stuff Cassini has seen," said Steve Wall, deputy team lead of Cassini's radar team, based at NASA's Jet Propulsion Laboratory, Pasadena, Calif. "One possibility is that the area is studded with rounded ice rocks. But we can't yet explain how that would happen."

Scientists are also intrigued by an area around 65 degrees south latitude and 293 degrees west longitude, which shows a close-up view of grooved, water-ice bedrock. The new images reveal undulations and other intricate patterns that had not been seen previously. They also now have measurements of the heights and depths of the grooves in this area, with the central groove measuring about 2,100 feet (650 meters) deep and 1.2 miles (2 kilometers) wide. It has slopes of about 33 degrees.

These images of Enceladus show some similarity to those obtained of Saturn's largest moon Titan.  Titan's large feature Xanadu is also very bright, as are areas surrounding the crater Sinlap.  Whether the bright areas seen here are due to the same, or very different, processes will be a subject of discussion as scientists continue to learn more about the moons of Saturn.

http://www.jpl.nasa.gov/news/news.cfm?release=2011-370

[Nixer]

Следующее событие - очень близкий пролет Дионы на расстоянии 99 км.

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http://www.nasa.gov/mission_pages/cassini/multimedia/pia14579.html

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Cassini to Make a Double Play

In an action-packed day and a half, NASA's Cassini spacecraft will be making its closest swoop over the surface of Saturn's moon Dione and scrutinizing the atmosphere of Titan, Saturn's largest moon.

The closest approach to Dione, about 61 miles (99 kilometers) above the surface, will take place at about 1:39 a.m. PST (4:39 a.m. EST) on Dec. 12. One of the questions Cassini scientists will be asking during this flyby is whether Dione's surface shows any signs of activity. Understanding Dione's internal structure will help address that question, so Cassini's radio science instrument will learn how highly structured the moon's interior is by measuring variations in the moon's gravitational tug on the spacecraft. The composite infrared spectrometer instrument will also look for heat emissions along fractures on the moon's surface.

Cassini will also be probing whether Dione, like another Saturnian moon, Rhea, has a tenuous atmosphere. Scientists expect a Dionean atmosphere – if there is one – to be much more ethereal than even Rhea's. Research published in journal Geophysical Research Letters and led by Sven Simon, a Cassini magnetometer team member at the University of Cologne, Germany, found magnetic field disturbances around Dione, hinting at a tenuous atmosphere. But scientists hope to get stronger confirmation by "tasting" the space around the moon with Cassini's ion and neutral mass spectrometer.

On Cassini's journey out from Dione toward Titan, the imaging science subsystem will turn back to look at Dione's distinctive, wispy fractures and a ridge called Janiculum Dorsa.

Cassini will approach within about 2,200 milles (3,600 kilometers) of the Titan surface, at about 12:11 p.m. PST (3:11 PM EST) on Dec. 13. At Titan, the composite infrared spectrometer will be making measurements to understand how the seasonal transition from spring to summer affects wind patterns in the atmosphere near Titan's north pole. It will also search for mist.

The visual and infrared mapping spectrometer and imaging science subsystem will be observing the same equatorial deserts where the imaging science subsystem saw sudden and dramatic surface changes last year, when Titan was experiencing early northern spring. One possibly theory is that rainstorms caused these changes. As Cassini recedes from Titan, the imaging cameras will also continue to observe the moon for another day to monitor any new weather systems. 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 the California Institute of Technology in Pasadena, manages the mission for NASA's Science Mission Directorate, Washington.

More Cassini information is available at http://www.nasa.gov/cassini and http://saturn.jpl.nasa.gov .

http://www.nasa.gov/mission_pages/cassini/whycassini/cassini20111209.html

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Portraits of Moons Captured by Cassini

NASA's Cassini spacecraft successfully completed its closest-ever pass over Saturn's moon Dione on Monday, Dec. 12, slaloming its way through the Saturn system on its way to tomorrow's close flyby of Titan. Cassini is expected to glide about 2,200 miles (3,600 kilometers) over the Titan surface on Dec. 13.

In the selection of the raw images obtained during the Cassini Dione flyby, Dione is sometimes joined by other moons. Mimas appears just beyond the dark side of Dione in one view. In another view, Epimetheus and Pandora appear together, along with Saturn's rings.

This Dione encounter was intended primarily for Cassini's composite infrared spectrometer and radio science subsystem. However, the imaging team did capture views of the distinctive, wispy fractures on the side of Dione that always trails in its orbit around Saturn. It also obtained images of a ridge called Janiculum Dorsa on the hemisphere of Dione that always leads in its orbit around Saturn. While other flybys produced more detailed views of the surface, the best resolved images from this flyby have scales ranging from about 1,100 feet (350 meters) to about 1,600 feet (500 meters) per pixel. Janiculum Dorsa will be imaged by Cassini at higher resolution in May 2012.

All of Cassini's raw images can be seen at http://saturn.jpl.nasa.gov/photos/raw/ .

http://www.jpl.nasa.gov/news/news.cfm?release=2011-385

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[Павел73]

А что это за белая соринка на нижнем снимке слева?

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Это сырые необработанные фотки. На них попадаются и покрупнее соринки:

[Space Alien]

"Кассини" сфотографировал полумесяц Титана



Издание Universe Today опубликовало снимок полумесяца Титана, сделанный зондом "Кассини". Фото и его описание можно посмотреть здесь - http://www.flickr.com/photos/lightsinthedark/6516896217/in/photostream/lightbox/.

Фотография была получена в результате совместной обработки трех изображений, сделанных в разных диапазонах электромагнитного спектра. На фото хорошо видна многослойная структура атмосферы Титана. Все снимки были сделаны с расстояния 3586 километров.

Зонд "Кассини" вместе с модулем "Гюйгенс" отправился в космос в 1997 году. В 2004 году аппараты достигли Сатурна. "Гюйгенс" отделился от "Кассини" в декабре этого же года и опустился на Титан. "Кассини" же продолжает работать на орбите газового гиганта и на настоящий момент (текущий этап миссии под названием "Солнцестояние", начавшийся в 2010 году, продлится до 2017 года).

В октябре 2011 стало известно, что астрономы составили подробную карту поверхности Титана. Сделано это было на основании снимков, выполненных зондом "Кассини". В частности, с помощью инфракрасных камер исследователи получили полноценные данные о ландшафте спутника.

http://lenta.ru/news/2011/12/19/cassini/

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NASA's Cassini Delivers Holiday Treats From Saturn

PASADENA, Calif. -- No team of reindeer, but radio signals flying clear across the solar system from NASA's Cassini spacecraft have delivered a holiday package of glorious images. The pictures, from Cassini's imaging team, show Saturn's largest, most colorful ornament, Titan, and other icy baubles in orbit around this splendid planet. The release includes images of satellite conjunctions in which one moon passes in front of or behind another. Cassini scientists regularly make these observations to study the ever-changing orbits of the planet's moons. But even in these routine images, the Saturnian system shines. A few of Saturn's stark, airless, icy moons appear to dangle next to the orange orb of Titan, the only moon in the solar system with a substantial atmosphere. Titan's atmosphere is of great interest because of its similarities to the atmosphere believed to exist long ago on the early Earth.

The images are online at: http://www.nasa.gov/cassini , http://saturn.jpl.nasa.gov and http://ciclops.org .

While it may be wintry in Earth's northern hemisphere, it is currently northern spring in the Saturnian system and it will remain so for several Earth years. Current plans to extend the Cassini mission through 2017 will supply a continued bounty of scientifically rewarding and majestic views of Saturn and its moons and rings, as spectators are treated to the passage of northern spring and the arrival of summer in May 2017.

"As another year traveling this magnificent sector of our solar system draws to a close, all of us on Cassini wish all of you a very happy and peaceful holiday season, " said Carolyn Porco, Cassini imaging team lead at the Space Science Institute, Boulder, Colo.

http://www.nasa.gov/mission_pages/cassini/whycassini/cassini20111222.html

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http://www.nasa.gov/mission_pages/cassini/multimedia/pia14909.html



http://www.nasa.gov/mission_pages/cassini/multimedia/pia14910.html



http://www.nasa.gov/mission_pages/cassini/multimedia/pia14911.html

[Павел73]

Красота! Картины художника-авангардиста...