posted 03-14-2011 09:15 PM               

quote:

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Originally posted by DChudwin:
An incredible animation of Cassini flying around Saturn and through its rings can be found here.

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posted 03-17-2011 10:07 PM               

As spring continues to unfold at Saturn, April showers on the planet's largest moon, Titan, have brought methane rain to its equatorial deserts, as revealed in images captured by NASA's Cassini spacecraft. This is the first time scientists have obtained current evidence of rain soaking Titan's surface at low latitudes.

Extensive rain from large cloud systems, spotted by Cassini's cameras in late 2010, has apparently darkened the surface of the moon. The best explanation is these areas remained wet after methane rainstorms. The observations released today in the journal Science, combined with earlier results in Geophysical Research Letters last month, show the weather systems of Titan's thick atmosphere and the changes wrought on its surface are affected by the changing seasons.

"It's amazing to be watching such familiar activity as rainstorms and seasonal changes in weather patterns on a distant, icy satellite," said Elizabeth Turtle, a Cassini imaging team associate at the Johns Hopkins University Applied Physics Lab in Laurel, Md., and lead author of today's publication. "These observations are helping us to understand how Titan works as a system, as well as similar processes on our own planet."

posted 09-03-2011 09:12 PM               

Here are some of the still frames of Hyperion as shown on the CICLOPS website.

A movie has been made of the approach pictures.

posted 12-22-2011 08:28 PM               

Cassini Delivers Holiday Treats From Across The Solar System

No team of reindeer was necessary for these holiday treats from NASA's Cassini spacecraft. A beam of radio signals, from clear across the solar system, has delivered a Christmas package of glorious images of Saturn's largest, most colorful ornament, Titan, and other icy baubles in orbit around this splendid planet. These treats are being featured today in a public release from the mission's imaging team.

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 great similarities to the atmosphere believed to exist long ago on the early Earth.

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

posted 03-10-2012 06:07 PM               

Proposed budget cuts in NASA's planetary program will reduce funds available to study the next outer planet mission. The three leading contenders are missions to Europa, Uranus or Enceladus. While all would be worthwhile, an Enceladus orbiter and lander/probe would be my first choice.

posted 03-30-2012 11:53 PM               

Cassini passed Enceladus first on March 27, coming within about 46 miles (74 kilometers) of the moon's surface. The encounter was primarily designed for Cassini's ion and neutral mass spectrometer, which "tasted" the composition of Enceladus' south polar plume. Other instruments, including the Cassini plasma spectrometer and composite infrared spectrometer, also took measurements.

Before the closest approach of this encounter, Cassini's cameras imaged the plume, which is comprised of jets of water ice and vapor, and organic compounds emanating from the south polar region. Later, the cameras captured a nine-frame mosaic of the surface of the moon's leading hemisphere as the spacecraft left the moon.

After the Enceladus encounter, Cassini passed the small moon Janus with a closest approach distance of 27,000 miles (44,000 kilometers). The planet was in the background in some of these views.

Early on March 28, the spacecraft flew by Dione at a distance of 27,000 miles (44,000 kilometers) and collected, among other observations, a nine-frame mosaic depicting the side of the moon that faces away from Saturn in its orbit.

posted 04-30-2012 09:07 PM               

Cassini images suggest Phoebe originated in the far-off Kuiper Belt, the region of ancient, icy, rocky bodies beyond Neptune's orbit. Data show Phoebe was spherical and hot early in its history, and has denser rock-rich material concentrated near its center. Its average density is about the same as Pluto, another object in the Kuiper Belt. Phoebe likely was captured by Saturn's gravity when it somehow got close to the giant planet.

Saturn is surrounded by a cloud of irregular moons that circle the planet in orbits tilted from Saturn's orbit around the sun, the so-called equatorial plane. Phoebe is the largest of these irregular moons and also has the distinction of orbiting backward in relation to the other moons. Saturn's large moons appear to have formed from gas and dust orbiting in the planet's equatorial plane. These moons currently orbit Saturn in that same plane.

"By combining Cassini data with modeling techniques previously applied to other solar system bodies, we've been able to go back in time and clarify why it is so different from the rest of the Saturn system," said Jonathan Lunine, a co-author on the study and a Cassini team member at Cornell University, Ithaca, N.Y.

Analyses suggest that Phoebe was born within the first 3 million years of the birth of the solar system, which occurred 4.5 billion years ago. The moon may originally have been porous but appears to have collapsed in on itself as it warmed up. Phoebe developed a density 40 percent higher than the average inner Saturnian moon.

Objects of Phoebe's size have long been thought to form as "potato-shaped" bodies and remained that way over their lifetimes. If such an object formed early enough in the solar system's history, it could have harbored the kinds of radioactive material that would produce substantial heat over a short timescale. This would warm the interior and reshape the moon.

"From the shape seen in Cassini images and modeling the likely cratering history, we were able to see that Phoebe started with a nearly spherical shape, rather than being an irregular shape later smoothed into a sphere by impacts," said co-author Peter Thomas, a Cassini team member at Cornell.

Phoebe likely stayed warm for tens of millions of years before freezing up. The study suggests the heat also would have enabled the moon to host liquid water at one time. This could explain the signature of water-rich material on Phoebe's surface previously detected by Cassini.

The new study also is consistent with the idea that several hundred million years after Phoebe cooled, the moon drifted toward the inner solar system in a solar-system-wide rearrangement. Phoebe was large enough to survive this turbulence.

More than 60 moons are known to orbit Saturn, varying drastically in shape, size, surface age and origin. Scientists using both ground-based observatories and Cassini's cameras continue to search for others.

posted 05-21-2012 09:49 PM               

According to CICLOPS (Cassini Imaging Central Laboratory for Operations):

With a close-approach distance of about 1,200 miles (1,900 kilometers), this was Cassini's closest flyby of the 2-mile-wide (3-kilometer-wide) Methone.

Earlier on May 20, Cassini flew by the larger moon Tethys at a distance of about 34,000 miles (54,000 kilometers), and several images from that encounter are included here. Tethys is 660 miles, or 1,062 kilometers, across.

Between 2004 and 2007, Cassini discovered Methone and two other small moons, Pallene and Anthe, between the orbits of Mimas and Enceladus. The three tiny moons, called the Alkyonides group, are embedded in Saturn's E ring and their surfaces are sprayed by ice particles originating from the jets of water ice, water vapor and organic compounds emanating from the south polar area of the moon Enceladus. The best previous Cassini images of Methone were taken on June 8, 2005, at a distance of about 140,000 miles (225,000 kilometers) and barely resolved this object.

posted 09-08-2012 02:47 PM               

Cassini continues to rack up big discoveries. In the past year alone, these have included such things as:

• Evidence of possible cryo-volcanic activity on Dione
  
• Determination of the fine structure of Enceladus' plumes by watching them occult two stars in Orion's Belt
  
• Using RADAR to image Enceladus and compare the results to Titan (using a radar signature of an object with a known composition to compare with Titan to try to understand what's going on there)
  
• "Hot spot" detected on Enceladus
  
• Determination that the leading hemispheres of Mimas and Tethys are colder than expected, possibly due to alteration of the surface composition from protons liberated from Saturn's cloudtops
  
• Determination that the icy satellites do not share the same chemical signatures as the rings (possible nano-iron or PAHs causing the rings to be redder than pure ice)
  
• Auroral hiss and electron beams around Enceladus; "van Allen"-like belts around Saturn with cavities in the field caused by the inner icy moons
  
• Observations of the "propeller" features in the outer A ring (clumps of ring material squeezed or stretched by unseen objects embedded in the rings). Observation that some propellers were not where they were expected to be after 2 years
  
• Material clumping in the F ring into strands and moonlets, which subsequently were pulled apart
  
• Determination of particle size distribution in the rings based on occultations of stars
  
• Seasonal variation in the bowl-shaped E ring

posted 01-14-2013 04:25 PM            

Eight years ago today, ESA's Huygens bounced, slid and wobbled its way to rest on the surface of Saturn's moon Titan, the first time a probe had touched down on an alien world in the outer Solar System.

The animation was created using real data recorded by Huygen's instruments, allowing us to witness this historical moment as if we had been there.

posted 02-10-2013 09:58 AM               

This recently released Cassini image is one of the best yet of the pattern. Saturn's rings are also visible in the upper right.

posted 04-03-2014 10:56 PM               

For years, the motto among astrobiologists — people who look for life in distant worlds, and try to understand what life is, exactly — has been "follow the water." You have to start the search somewhere, and scientists have started with liquid water because it's the essential agent for all biochemistry on Earth.

Now they've followed the water to a small, icy moon orbiting Saturn. Scientists reported Thursday that Enceladus, a shiny world about 300 miles in diameter, has a subsurface "regional sea" with a rocky bottom.

posted 10-17-2014 07:39 PM               

When it comes to Saturn’s moons, water-squirting Enceladus and the hydrocarbon lakes of Titan typically steal the spotlight. But now, scientists think that lesser-known Mimas may be harboring a strange secret of its own. Scientists who studied the ‘Death Star’ moon with NASA’S Cassini spacecraft have discovered a weird wobble in its motions that could mean one of two things: Either Mimas has an oddly elongated core, or it’s hiding an ocean inside its icy body...

The findings, described in the journal Science, shed new light on a mysterious but often-overlooked moon that could hold clues to its early formation.

Mimas is an icy moon that’s 246 miles wide and whose most distinctive feature is the 88-mile-wide Herschel crater – a giant Cyclops-like indentation that makes the moon resemble the planet-obliterating superweapon from "Star Wars" that's known as the Death Star.