"Кассини" !

[tnt22]

CassiniSaturn‏Подлинная учетная запись @CassiniSaturn 7 ч. назад

This series of unprocessed images shows #Saturn's rings passing in front of the star Kappa Orionis. More raw images: https://go.nasa.gov/2guHnlH

[tnt22]

CassiniSaturn‏Verified account @CassiniSaturn 2h ago

Small Wonders: comparing three of #Saturn's tiny ring moons: Atlas, Daphnis and Pan https://go.nasa.gov/2snOD7r 

https://saturn.jpl.nasa.gov/resources/7695/

Small Wonders

Спойлер

Photojournal: PIA21449

[свернуть]

June 28, 2017

This montage of views from NASA's Cassini spacecraft shows three of Saturn's small ring moons: Atlas, Daphnis and Pan at the same scale for ease of comparison.

Two differences between Atlas and Pan are obvious in this montage. Pan's equatorial band is much thinner and more sharply defined, and the central mass of Atlas (the part underneath the smooth equatorial band) appears to be smaller than that of Pan.

Спойлер

Images of Atlas and Pan taken using infrared, green and ultraviolet spectral filters were combined to create enhanced-color views (Figure A), which highlight subtle color differences across the moons' surfaces at wavelengths not visible to human eyes. (The Daphnis image in figure A was colored using the same green filter image for all three color channels, adjusted to have a realistic appearance next to the other two moons.)

A version of the montage using only monochrome images is also provided (Figure B).

All of these images were taken using the Cassini spacecraft narrow-angle camera. The images of Atlas were acquired on April 12, 2017, at a distance of 10,000 miles (16,000 kilometers) and at a sun-moon-spacecraft angle (or phase angle) of 37 degrees. The images of Pan were taken on March 7, 2017, at a distance of 16,000 miles (26,000 kilometers) and a phase angle of 21 degrees. The Daphnis image was obtained on Jan. 16, 2017, at a distance of 17,000 miles (28,000 kilometers) and at a phase angle of 71 degrees. All images are oriented so that north is up.

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.

Credit

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

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[tnt22]

CassiniSaturn‏Подлинная учетная запись @CassiniSaturn 7 мин назад

Halfway there: we've successfully completed ring crossing #11 of 22 in our #GrandFinale mission. More: https://go.nasa.gov/1Up1oba

[tnt22]

https://saturn.jpl.nasa.gov/mission/grand-finale/grand-finale-orbit-guide/#Orbit_12

IN PROGRESS: Orbit 282 - July 3 - July 9

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

Apoapse	Jul 3	3:54 a.m.	8:54 p.m. (July 2)
Ring Crossing #12	Jul 6	9:31 a.m.	2:31 a.m.	Cassini again ventures into the D ring. Spacecraft will be shielded by its High Gain Antenna.
Downlink	Jul 7	5:44 a.m.	10:44 p.m. (Jul 6)	Estimated Earth Received Time (ERT) is 11:59 p.m. PDT on July 6.

[/li]
• During this orbit, Cassini's Ultraviolet Imaging Spectrograph (UVIS) stares at the star Kappa Canis Majoris, as parts of the C ring and A ring pass between the spacecraft and the star. The spacecraft's Composite Infrared Spectrometer (CIRS) observes the occultation as well.
• Cassini's imaging cameras, the Imaging Science Subsystem (ISS), observes some of Saturn's known ring propeller features, then targets the border region of the F ring and A ring to study ring dynamics there.
• Cassini's UVIS instrument also studies small-scale structures in the rings.
• During this orbit's ring-plane crossing, the spacecraft is oriented such that its high-gain antenna (the big dish) faces forward (called "HGA to RAM") to help shield the spacecraft from ring particles.
• Also during ring-plane crossing, in the brief period in which impacts are most likely, the Radio and Plasma Wave Science (RPWS) instrument "listens" for the impacts of ring particles, which produce detectable plasma clouds when they strike the spacecraft. The antenna protrudes several meters beyond the protection of the high-gain antenna and so still detects impacts.
• During this orbit, Cassini gets within 2,320 miles (3,730 kilometers) of Saturn's 1-bar level. Cassini also passes within 2,470 miles (3,980 kilometers) of the inner edge of Saturn's D ring.
  

[tnt22]

CassiniSaturn‏Подлинная учетная запись @CassiniSaturn 9 ч. назад

One of the highest resolution views ever of #Saturn's moon Epimetheus offers vivid reminders of the hazards of space https://go.nasa.gov/2tgTyul 

https://saturn.jpl.nasa.gov/resources/7700/

Zoom-in on Epimetheus

Спойлер

Photojournal: PIA21335

[свернуть]

July 3, 2017

This zoomed-in view of Epimetheus, one of the highest resolution ever taken, shows a surface covered in craters, vivid reminders of the hazards of space.

Epimetheus (70 miles or 113 kilometers across) is too small for its gravity to hold onto an atmosphere.  It is also too small to be geologically active.  There is therefore no way to erase the scars from meteor impacts, except for the generation of new impact craters on top of old ones.

This view looks toward anti-Saturn side of Epimetheus. North on Epimetheus is up and rotated 32 degrees to the right. The image was taken with the Cassini spacecraft narrow-angle camera on Feb. 21, 2017 using a spectral filter which preferentially admits wavelengths of near-infrared light centered at 939 nanometers.

Спойлер

The view was acquired at a distance of approximately 9,300 miles (15,000 kilometers) from Epimetheus and at a Sun-Epimetheus-spacecraft, or phase, angle of 71 degrees. Image scale is 290 feet (89 meters) 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 http://saturn.jpl.nasa.gov and http://www.nasa.gov/cassini. The Cassini imaging team homepage is at http://ciclops.org.

Credit

Credit: NASA/JPL-Caltech/Space Science Institute
 
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[tnt22]

CassiniSaturn‏Подлинная учетная запись @CassiniSaturn 3 ч. назад

In a few hours, the spacecraft will thread the gap between #Saturn and its innermost ring. You can follow along at: https://go.nasa.gov/2aNCy6t 

[SashaBad]

Шероховатость поверхности углеводородных морей Титана
 http://www.sciencedirect.com/science/article/pii/S0012821X17303163

Проанализированы данные свойств поверхности (шероховатости и диэлектрической проницаемости) жидких углеводородных образований Лигея, Кракен и Пунга, применяя метод радиолокационной статистической разведки (RSR), для наблюдений радара Cassini, сделанных в режиме высотомера в начале лета в северном полушарии Титана. Во время наблюдений Кракена и Лигеи, неровности были ограничены в пределах среднеквадратичных высот 1,5-2,5 мм (аналогичные высотам волн 6-10 мм), корреляционные длины 45-115 мм и соответствующие эффективным склонам 1,1 -2.4 °.
Нижняя граница этих диапазонов должна учитываться, если состав морей является доминирующим по метану. Это первые измерения, которые одновременно ограничивают как вертикальные, так и горизонтальные параметры шероховатости морей Титана. Результаты являются репрезентативными для общих свойств морской поверхности изученных треков и свидетельствуют о том, что тихие поверхности являются преобладающим трендом морей в северном полушарии раннем летом. Поля более грубых текстур, если они существуют, могут развиваться главным образом над локальными территориями, и/или могут существовать в течение не значительных периодов времени.

[tnt22]

CassiniSaturn‏Подлинная учетная запись @CassiniSaturn 7 ч. назад

We've successfully completed ring crossing #12 of 22. Learn more about our #GrandFinale orbits: https://go.nasa.gov/2qcf2Vx 

[tnt22]

CassiniSaturn‏Подлинная учетная запись @CassiniSaturn 5 ч. назад

For #SaturnSaturday, here's our #GrandFinale by the numbers. More: https://go.nasa.gov/1Up1oba 

[tnt22]

https://saturn.jpl.nasa.gov/resources/7701/

Dawn's Early Light



Photojournal: PIA21336

July 6, 2017

The light of a new day on Saturn illuminates the planet's wavy cloud patterns and the smooth arcs of the vast rings.

Спойлер

The light has traveled around 80 minutes since it left the sun's surface by the time it reaches Saturn. The illumination it provides is feeble; Earth gets 100 times the intensity since it's roughly ten times closer to the sun. Yet compared to the deep blackness of space, everything at Saturn still shines bright in the sunlight, be it direct or reflected.

This view looks toward the sunlit side of the rings from about 10 degrees above the ring plane. The image was taken with the Cassini spacecraft wide-angle camera on Feb. 25, 2017 using a spectral filter which preferentially admits wavelengths of near-infrared light centered at 939 nanometers.

The view was obtained at a distance of approximately 762,000 miles (1.23 million kilometers) from Saturn. Image scale is 45 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 http://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://saturn.jpl.nasa.gov/mission/grand-finale/grand-finale-orbit-guide/#Orbit_13

IN PROGRESS - July 9 - July 16

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

Apoapse	Jul 9	3:13 p.m.	8:13 a.m.
Ring Crossing #13	Jul 12	8:44 p.m.	1:44 p.m.
Downlink	Jul 13	8:17 a.m.	1:17 p.m.	Estimated Earth Received Time (ERT) is 2:33 a.m. PDT on July 13.

[/li]
• During this orbit, Cassini's Composite Infrared Spectrometer (CIRS) observes the lit side of the middle A-ring to determine its composition and structure. The CIRS instrument then targets the point where Saturn's shadow falls across the B-ring, studying how the ring's temperature changes as it crosses into Saturn's shadow. These CIRS observations reveal details about the structure of the ring particles themselves, which are too small for Cassini's cameras to resolve.
• Cassini's imaging cameras, the Imaging Science Subsystem (ISS), observes some of Saturn's known ring propeller features. The ISS also performs a high-resolution scan of Saturn's C ring and inner B ring
• With Cassini about 31,100 miles (50,000 kilometers) from Saturn's lower atmosphere, the Ion and Neutral Mass Spectrometer (INMS) samples the exosphere and ionosphere of Saturn and of the atmosphere-ionosphere of Saturn's rings. On a later orbit (Orbit 288 ), the INMS will sample Saturn's visible, much denser atmosphere for the first time.
• During this orbit, Cassini gets within 1,780 miles (2,860 kilometers) of Saturn's 1-bar level. Cassini also passes within 3,020 miles (4,850 kilometers) of the inner edge of Saturn's D ring.
  

[tnt22]

https://saturn.jpl.nasa.gov/news/3078/halfway-home/

| July 6, 2017
Halfway Home

By Jay Thompson


On June 28 in a testing lab at the Jet Propulsion Laboratory, Cassini engineers led by Julie Webster (right) were looking for any imperfections in the final commands to be transmitted July 7 to the spacecraft. Cassini will then autonomously operate under those instructions fr om July 10 through end of mission on Sept. 15. Credit: NASA/JPL-Caltech

Time is running out for Cassini.

In April, the Cassini spacecraft began the mission's Grand Finale — a series of 22 dives through the 1,500-mile (2,000-kilometer) gap between Saturn and its rings, where no spacecraft had explored before. On June 29, the spacecraft completed its eleventh dive through the gap, putting it halfway through the final phase of its nearly 20-year journey in space.

So far, the science observations for the Grand Finale are going as planned, and the spacecraft — 19 years and eight months after launch — is in good shape. "It's doing exactly what it's supposed to do," said Julie Webster, Cassini's manager of spacecraft operations. "The spacecraft is executing every command that's asked of it."

Cassini needs only to stay out of trouble for the next two and a half months to reach the end of its mission, on Sept. 15, when the spacecraft will triumphantly plunge into Saturn's atmosphere. On that day, Cassini will transmit data about its surroundings until the spacecraft can no longer fight the atmosphere with its attitude control thrusters. Before that day arrives, however, Cassini requires one more set of instructions.

Because communication with the spacecraft is not instantaneous, Cassini can't be controlled in real time. Therefore, the spacecraft must operate autonomously using instructions transmitted from Earth. On the same day as Cassini's eleventh dive through the gap, the mission's engineers and scientists finalized the spacecraft's last set of instructions.

Спойлер

In the mission control room at JPL, a screen displays the days, hours, minutes, and seconds remaining until the Cassini spacecraft's mission-ending plunge into Saturn's atmosphere. The photo is from June 28 — a real-time countdown clock can be found in the bottom right of the mission homepage. Credit: NASA/JPL-Caltech
 
Each of Cassini's sets of instructions are called a sequence — a series of computer commands for Cassini's science instruments, communication system, attitude control thrusters and other subsystems to follow. A sequence is like a musical score, which can be separated into different sets of sheet music for each of a spacecraft's subsystems to read and perform from. When all of  Cassini's systems perform in concert, they produce a symphony — not of music, but of engineering achievement and scientific discovery.

Cassini's final sequence, called Sequence 101, controls the spacecraft from July 10 through Cassini's last day, Sept. 15. The honor of transmitting, or "uplinking," Cassini's final sequence falls on NASA's Deep Space Network station in Canberra, Australia, wh ere the 70-meter diameter radio antenna will send the commands to the spacecraft on July 7.

After their final sequence approval meeting, the spacecraft operations team at NASA's Jet Propulsion Laboratory celebrated with pizza.

[свернуть]

[Сергио]

SashaBad пишет:
Шероховатость поверхности углеводородных морей Титана
 http://www.sciencedirect.com/science/article/pii/S0012821X17303163
 
Проанализированы данные свойств поверхности (шероховатости и диэлектрической проницаемости) жидких углеводородных образований Лигея, Кракен и Пунга, применяя метод радиолокационной статистической разведки (RSR), для наблюдений радара Cassini, сделанных в режиме высотомера в начале лета в северном полушарии Титана. Во время наблюдений Кракена и Лигеи, неровности были ограничены в пределах среднеквадратичных высот 1,5-2,5 мм (аналогичные высотам волн 6-10 мм), корреляционные длины 45-115 мм и соответствующие эффективным склонам 1,1 -2.4 °.
Нижняя граница этих диапазонов должна учитываться, если состав морей является доминирующим по метану. Это первые измерения, которые одновременно ограничивают как вертикальные, так и горизонтальные параметры шероховатости морей Титана. Результаты являются репрезентативными для общих свойств морской поверхности изученных треков и свидетельствуют о том, что тихие поверхности являются преобладающим трендом морей в северном полушарии раннем летом. Поля более грубых текстур, если они существуют, могут развиваться главным образом над локальными территориями, и/или могут существовать в течение не значительных периодов времени.

начал искать гренландию и баренцево море на карте

[Чебурашка]

А по вязкости морей Титана есть какие-то данные  :?:

Оно невязкое как вода? Или на масло по консистенции похоже? Или может как желе?

[SashaBad]

Вязкость метана в жидком виде равна 0,08 от показателя земных морей. Плотность - 45% от плотности воды.
Но моря Титана это смесь жидких углеводородов — метана, этана и некоторых других. Как всё это ведёт себя в условиях Титана думаю окончательно не понятно ни кому.
Если интересно, поищите у Alexander Hayes. 
http://astro.cornell.edu/members/alexander-hayes.html
Или у других исследователей работающих с результатами Cassini по Титану

[tnt22]

CassiniSaturn‏Подлинная учетная запись @CassiniSaturn 10 мин. назад

We're about to make our 13th crossing between #Saturn & its rings, as simulated here by @NASA_Eyes. Details: http://go.nasa.gov/1Up1oba

[tnt22]

CassiniSaturn‏Подлинная учетная запись @CassiniSaturn 8 мин. назад

See the latest unprocessed images from Saturn here: https://go.nasa.gov/2guHnlH 

[tnt22]

CassiniSaturn‏Подлинная учетная запись @CassiniSaturn 3 мин. назад

Yesterday's ring plane crossing was successful. Nine remain in our #GrandFinale mission. Details: https://go.nasa.gov/2qcf2Vx 

[tnt22]

CassiniSaturn‏Подлинная учетная запись @CassiniSaturn 14 июл.

We captured this unprocessed close-up of Saturn's rings during the latest ring crossing on 7/12. See more raw images https://go.nasa.gov/2guHnlH 

[tnt22]

https://saturn.jpl.nasa.gov/mission/grand-finale/grand-finale-orbit-guide/#Orbit_14

IN PROGRES - Orbit 284 - July 16 - July 22

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

Apoapse	Jul 16	2:21 a.m.	7:21 p.m. (July 15)
Ring Crossing #14	Jul 19	7:50 a.m.	12:50 a.m.
Downlink	Jul 19	7:50 a.m.	12:50 a.m.	Cassini will be communicating with Earth during the ring crossing. Estimated Earth Received Time (ERT) is 2:06 a.m. PDT on July 19.

[/li]
• During this orbit, Cassini's Radio Science Subsystem (RSS) performs its last science observations of the mission. The instrument conducts radio occultations of Saturn's ring system and runs a gravity experiment to characterize Saturn's gravitational field with unprecedented detail. RSS determines Saturn's gravity by very precisely tracking the orbit of Cassini relative to the Earth as the spacecraft skims Saturn's atmosphere. By measuring the Doppler shift in Cassini's radio signal, scientists can learn how mass is distributed within Saturn. In addition, Cassini simultaneously feels the gravitational pull of the rings (the B-Ring, in particular) and determines their mass very accurately. The mass helps scientists determine the age of the ring system.
• When Cassini is in the segment of this orbit in which it's nearest to Saturn, the spacecraft rolls so that the Magnetometer (MAG) can collect unique measurements that will lead to a better understanding of Saturn's magnetic field, the planet's rotation rate, the size of the central core and other characteristics of Saturn.
• Then the Visible and Infrared Mapping Spectrometer (VIMS) leads an observation of Saturn's southern hemisphere at night.
• During this orbit, Cassini gets within 1,740 miles (2,790 kilometers) of Saturn's 1-bar level. Cassini also passes within 3,050 miles (4910 kilometers) of the inner edge of Saturn's D ring.