Cassini - is it just me who's excited?

[remcook]

sounds very reasonable
I don't know the details and the theory has not yet been published as far as i can tell

[Astronuc]

Evidence from NASA's Cassini spacecraft suggests Neptune's Triton may not be the only satellite with cryovolcanism. Saturn's moon Titan may be cryovolcanic as well. Long before Cassini settled into orbit around Saturn June 30, 2004, planetary geologists suspected super-chilled cryovolcanoes lurk beneath Titan's surface.

The Cassini orbiter's radar and infrared mapping of planet-size Titan reveal features that remind scientists of volcanic structures on other worlds. The most remarkable to date is a 120-mile-wide (180 kilometers) circular feature called Ganesa Macula. Although no topographic data has yet been obtained, the mountain resembles volcanoes on Venus or Earth — specifically pancake domes or shield volcanoes, like those common in Hawaii. Titan's Ganesa is about the same scale as large shield volcanoes on Earth. For reference, the world's largest shield volcano, Mauna Loa, rises 14,000 feet (4,300 meters) above sea level.

http://www.astronomy.com/asy/default.aspx?c=a&id=4052

[remcook]

some more on iapetus' bulge:

link

AGU abstract

[Astronuc]

This is so bloody cool!!!!

PIA06082: Saturn Movie

http://photojournal.jpl.nasa.gov/catalog/PIA06082

http://photojournal.jpl.nasa.gov/catalog/PIA06083

Also - storm alley on Saturn - http://saturn.jpl.nasa.gov/multimedia/images/image-details.cfm?imageID=1963

See also -
http://photojournal.jpl.nasa.gov/catalog/PIA05386

 

[Astronuc]

Another flyby of Titan coming up on May 20,2006 

Meanwhile - Stunning Vistas
May 12, 2006  Full-Res: PIA07786 
http://saturn.jpl.nasa.gov/multimedia/images/image-details.cfm?imageID=2131

The Cassini spacecraft delivers this stunning vista showing small, battered Epimetheus and smog-enshrouded Titan, with Saturn's A and F rings stretching across the scene.
 
The prominent dark region visible in the A ring is the Encke Gap, in which the moon Pan and several narrow ringlets reside. Moon-driven features that mark the A ring are easily seen to the left and right of the Encke Gap. The Encke Gap is 325 kilometers (200 miles) wide. Pan is 26 kilometers (16 miles) across.

In an optical illusion, the narrow F ring, outside the A ring, appears to fade across the disk of Titan. A couple of bright clumps can be seen in the F ring.

Epimetheus is 116 kilometers (72 miles) across and giant Titan is 5,150 kilometers (3,200 miles) across.

The image was taken in visible light with the Cassini spacecraft narrow-angle camera on April 28, 2006, at a distance of approximately 667,000 kilometers (415,000 miles) from Epimetheus and 1.8 million kilometers (1.1 million miles) from Titan. The image captures the illuminated side of the rings. The image scale is 4 kilometers (2 miles) per pixel on Epimetheus and 11 kilometers (7 miles) per pixel on Titan.

Dunes and more dunes
http://saturn.jpl.nasa.gov/multimedia/images/image-details.cfm?imageID=2132

 

[remcook]

...and some more about Iapetus' bulge: a ring origin??

http://www.agu.org/pubs/crossref/2006/2005GL025386.shtml

[Astronuc]

New ring discovered around Saturn!
http://news.bbc.co.uk/2/hi/science/nature/5368644.stm

The Cassini spacecraft has identified a faint, previously unknown ring circling the giant planet Saturn.
 
It appears to be composed of material blasted off the surface of two saturnian moons by meteoroid impacts.

The moons Janus and Epimetheus may be too small to hold on to dust kicked out by these impacts, so it escapes into space, spreading out into a ring.

The tenuous, wispy ring coincides with the orbits of these two moons, mission scientists noted.

Researchers expected meteoroid impacts on Janus and Epimetheus to kick particles off the moons' surfaces and inject them into an orbit around Saturn. But they were surprised to find such a well-defined ring at this location.

Cast in shadow

Scientists owe their discovery to a highly unusual event: a solar occultation which put Cassini in the Sun's shadow for 12 hours.

The longest occultation of the four-year mission allowed the spacecraft to scrutinise the rings as they were strongly backlit by the Sun.

[remcook]

with that press release also an image of Earth from Cassini (cool!) and Enceladus sweeping through its home-made ring. Very neat stuff.

[Astronuc]

This is an incredible image of Saturn.

http://antwrp.gsfc.nasa.gov/apod/ap061016.html

 

[Astronuc]

RELEASE: 06-344 - NASA Sees Into the Eye of a Monster Storm on Saturn

NASA's Cassini spacecraft has seen something never before seen on another planet -- a hurricane-like storm at Saturn's South Pole with a well-developed eye, ringed by towering clouds.

The "hurricane" spans a dark area inside a thick, brighter ring of clouds. It is approximately 5,000 miles across, or two thirds the diameter of Earth.

"It looks like a hurricane, but it doesn't behave like a hurricane," said Andrew Ingersoll, a member of Cassini's imaging team at the California Institute of Technology, Pasadena. "Whatever it is, we're going to focus on the eye of this storm and find out why it's there."

A movie taken by Cassini's camera over a three-hour period reveals winds around Saturn's South Pole blowing clockwise at 350 miles per hour. The camera also saw the shadow cast by a ring of towering clouds surrounding the pole, and two spiral arms of clouds extending from the central ring. These ring clouds, 20 to 45 miles above those in the center of the storm, are two to five times taller than the clouds of thunderstorms and hurricanes on Earth.

Eye-wall clouds are a distinguishing feature of hurricanes on Earth. They form where moist air flows inward across the ocean's surface, rising vertically and releasing a heavy rain around an interior circle of descending air that is the eye of the storm itself. Though it is uncertain whether such moist convection is driving Saturn's storm, the dark "eye" at the pole, the eye-wall clouds and the spiral arms together indicate a hurricane-like system.

Distinctive eye-wall clouds have not been seen on any planet other than Earth. Even Jupiter's Great Red Spot, much larger than Saturn's polar storm, has no eye or eye-wall, and is relatively calm at the center.

This giant Saturnian storm is apparently different than hurricanes on Earth because it is locked to the pole and does not drift around like terrestrial hurricanes. Also, since Saturn is a gaseous planet, the storm forms without an ocean at its base.

In the Cassini imagery the eye looks dark at light wavelengths where methane gas absorbs the light and only the highest clouds are visible.

"The clear skies over the eye appear to extend down to a level about twice as deep as the usual cloud level observed on Saturn," said Kevin H. Baines, of Cassini's visual and infrared mapping spectrometer team at NASA's Jet Propulsion Laboratory, Pasadena, Calif. "This gives us the deepest view yet into Saturn over a wide range of wavelengths, and reveals a mysterious set of dark clouds at the bottom of the eye."

Infrared images taken by the Keck I telescope in Mauna Kea, Hawaii, had previously shown Saturn's South Pole to be warm. Cassini's composite infrared spectrometer has confirmed this with higher resolution temperature maps of the area. The spectrometer observed a temperature increase of about 4 degrees Fahrenheit at the pole. The instrument measured high temperatures in the upper troposphere and stratosphere, regions higher in the atmosphere than the clouds seen by the Cassini imaging instruments.

"The winds decrease with height, and the atmosphere is sinking, compressing and heating over the South Pole," said Richard Achterberg, a member of Cassini's composite infrared spectrometer team at NASA's Goddard Spaceflight Center, Greenbelt, Md.

Observations taken over the next few years, as the South Pole season changes from summer to fall, will help scientists understand the role seasons play in driving the dramatic meteorology at the south pole of Saturn.

WOW!

The "hurricane" spans a dark area inside a thick, brighter ring of clouds. It is approximately 8,000 kilometers (5,000 miles) across, or two thirds the diameter of Earth.

http://www.nasa.gov/mission_pages/cassini/media/cassini-20061109.html

[Astronuc]

This month, Cassini does the first of a series of Titan flybys this year. This year, Cassini has 17 flybys of the intriguing moon, the most of any year during the four-year prime mission.

Both luminous and translucent, the C ring sweeps out of the darkness of Saturn's shadow and obscures the planet at lower left. The ring is characterized by broad, isolated bright areas, or "plateaus," surrounded by fainter material.

http://www.nasa.gov/mission_pages/cassini/multimedia/pia08855.html

And - Huygens’s second landing anniversary – the surprises continue
http://www.esa.int/esaSC/SEM7QJRMTWE_index_0.html

[Astronuc]

Mapping Titan's Changes - old photos from October 2005 - Jan 2006.
http://www.nasa.gov/mission_pages/cassini/multimedia/pia02145.html

It will be interesting if they get similar images this month for a comparison one year later.

[Astronuc]

Still going strong - Cassini images the southern region of Saturn.

http://www.nasa.gov/mission_pages/cassini/multimedia/pia08898.html

From beneath the ringplane, the Cassini spacecraft takes stock of Saturn's southern skies and peeks through the rings and beyond their shadows at the northern latitudes.

The image was taken by the Cassini spacecraft wide-angle camera using a combination of spectral filters sensitive to wavelengths of polarized infrared light. This type of infrared filter view allows Cassini's cameras to see through the planet's overlying haze and observe fine detail in its ever-moving cloud bands.

http://www.nasa.gov/mission_pages/cassini/multimedia/pia08896.html

[Astronuc]

Cassini Images Bizarre Hexagon on Saturn 
March 27, 2007

Pasadena, Calif. -- An odd, six-sided, honeycomb-shaped feature circling the entire north pole of Saturn has captured the interest of scientists with NASA's Cassini mission.

NASA's Voyager 1 and 2 spacecraft imaged the feature over two decades ago. The fact that it has appeared in Cassini images indicates that it is a long-lived feature. A second hexagon, significantly darker than the brighter historical feature, is also visible in the Cassini pictures. The spacecraft's visual and infrared mapping spectrometer is the first instrument to capture the entire hexagon feature in one image.

"This is a very strange feature, lying in a precise geometric fashion with six nearly equally straight sides," said Kevin Baines, atmospheric expert and member of Cassini's visual and infrared mapping spectrometer team at NASA's Jet Propulsion Laboratory, Pasadena, Calif. "We've never seen anything like this on any other planet. Indeed, Saturn's thick atmosphere where circularly-shaped waves and convective cells dominate is perhaps the last place you'd expect to see such a six-sided geometric figure, yet there it is."

The hexagon is similar to Earth's polar vortex, which has winds blowing in a circular pattern around the polar region.  On Saturn, the vortex has a hexagonal rather than circular shape. The hexagon is nearly 25,000 kilometers (15,000 miles) across. Nearly four Earths could fit inside it.

The new images taken in thermal-infrared light show the hexagon extends much deeper down into the atmosphere than previously expected, some 100 kilometers (60 miles) below the cloud tops. A system of clouds lies within the hexagon. The clouds appear to be whipping around the hexagon like cars on a racetrack.

. . .

The Saturn north pole hexagon has not been visible to Cassini's visual cameras, because it's winter in that area, so the hexagon is under the cover of the long polar night, which lasts about 15 years. The infrared mapping spectrometer can image Saturn in both daytime and nighttime conditions and see deep inside. It imaged the feature with thermal wavelengths near 5 microns (seven times the wavelength visible to the human eye) during a 12-day period beginning on Oct. 30, 2006. As winter wanes over the next two years, the feature may become visible to the visual cameras.

http://www.jpl.nasa.gov/news/news.cfm?release=2007-034

This is amazing!

[remcook]

yes very cool. It has been there since the voyager days at least!