MIMAS, THE "DEATH STAR" MOON

FROM:  NASA

A thin sliver of Mimas is illuminated, the long shadows showing off its many craters, indicators of the moon's violent history. The most famous evidence of a collision on Mimas (246 miles, or 396 kilometers across) is the crater Herschel that gives Mimas its Death Star-like appearance.  North on Mimas is up and rotated 40 degrees to the right. The image was taken in visible light with the Cassini spacecraft narrow-angle camera on May 20, 2013. The view was acquired at a distance of approximately 100,000 miles (200,000 kilometers) from Mimas and at a Sun-Mimas-spacecraft, or phase, angle of 130 degrees. Image scale is 4,000 feet (1 kilometer) per pixel. 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, D.C. 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, Colo.  Credit: NASA/JPL-Caltech/Space Science Institute.

PORTRAIT OF SATURN LOOKING DOWN ON RINGS

FROM:  NASA 

This portrait looking down on Saturn and its rings was created from images obtained by NASA's Cassini spacecraft on Oct. 10, 2013. It was made by amateur image processor and Cassini fan Gordan Ugarkovic. This image has not been geometrically corrected for shifts in the spacecraft perspective and still has some camera artifacts.The mosaic was created from 12 image footprints with red, blue and green filters from Cassini's imaging science subsystem. Ugarkovic used full color sets for 11 of the footprints and red and blue images for one footprint. 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, D.C. 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, Colo.

LITTLE BITTY PRETTY MOON

FROM: NASA

Beautiful Plumage
Like a proud peacock displaying its tail, Enceladus shows off its beautiful plume to the Cassini spacecraft's cameras.

Enceladus (313 miles, or 504 kilometers across) is seen here illuminated by light reflected off Saturn.

This view looks toward the Saturn-facing side of Enceladus. North on Enceladus is up and rotated 45 degrees to the right. The image was taken in visible light with the Cassini spacecraft narrow-angle camera on Jan. 18, 2013.

The view was acquired at a distance of approximately 483,000 miles (777,000 kilometers) from Enceladus and at a Sun-Enceladus-spacecraft, or phase, angle of 173 degrees. Image scale is 3 miles (5 kilometers) per pixel.

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, D.C. 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, Colo. Credit: NASA/JPL-Caltech/Space Science Institute

SATURN'S HURRICANE

FROM: NASA
Mysterious Hurricane at Saturn's North Pole
Narrated video about a hurricane-like storm seen at Saturn's north pole by NASA's Cassini spacecraft.

VIDEO OF THE HUYGENS PROBE LANDING ON TITAN

FROM: NASA

 When Huygens Met Titan

This animation re-creates the final descent of ESA's Huygens probe as it landed on Titan on Jan. 14, 2005, after it was dropped off by NASA's Cassini spacecraft.

LAKE LEVELS ON TITAN

FROM: NASA

Titan's Lake District, One Season Later
These images obtained by NASA's Cassini spacecraft show Titan's stable northern lake district. Cassini's radar instrument obtained the recent images on May 22, 2012. It observed some previously unseen regions but also some regions containing lakes that were last observed about six years-nearly one Titan season--ago. This marks the longest time interval between lake observations in the northern hemisphere.

The top image here shows part of the radar swath from May 22, 2012, centered near 79 degrees north latitude, 58 degrees west longitude, and about 220 by 47 miles (350 by 75 kilometers) in dimension. At the bottom, parts of this image are compared with those obtained in 2006. (The images appear slightly different from previous releases because they use a new filtering technique). In 2006, it was winter in the northern hemisphere and the lakes were in the dark. Although Titan spring began in 2009 and the sun has now risen over the lakes, there is no apparent change in lake levels since the 2006 flybys, consistent with climate models that predict stability of liquid lakes over several years. This shows that the northern lakes are not transient weather events, in contrast to the temporary darkening of parts of the equator after a rainstorm in 2010 (PIA 12819).

Changes in lake levels may still be detected later in the mission as Cassini continues to observe these high northern latitudes into the beginning of summer in 2017. At that point, the sun may cause evaporation. However, the lack of significant change over six years sets important constraints for climate models and the stability of liquids on Titan. Illumination is coming from the bottom.

The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. NASA's Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the mission for NASA's Science Mission Directorate, Washington, DC. The Cassini orbiter was designed, developed and assembled at JPL. The radar instrument was built by JPL and the Italian Space Agency, working with team members from the United States and several European countries. Image Credit: NASA/JPL-Caltech/ASI

A PAIR OF MOONS NEAR SATURN

FROM: NASA
Saturn's MoonsThe Cassini spacecraft watches a pair of Saturn's moons, showing the hazy orb of giant Titan beyond smaller Tethys. This view looks toward the Saturn-facing sides of Titan (3,200 miles, or 5,150 kilometers across) and Tethys (660 miles, or 1,062 kilometers across).

The image was taken in visible green light with the Cassini spacecraft narrow-angle camera on Oct. 18, 2010. The view was obtained at a distance of approximately 1.6 million miles (2.5 million kilometers) from Titan and at a Sun-Titan-spacecraft, or phase, angle of 55 degrees. The view was obtained at a distance of approximately 930,000 miles (1.5 million kilometers) from Tethys and at a Sun-Tethys-spacecraft, or phase, angle of 55 degrees. Image scale is 15 kilometers (9 miles) per pixel on Titan and 6 miles (9 kilometers) per pixel on Tethys.

Image Credit: NASA/JPL/Space Science Institute

NASA'S CASSINI FINDS SATURN'S MOON PHOEBE HAS PLANET-LIKE QUALITIES

FROM:  NASA
WASHINGTON -- Data from NASA's Cassini mission reveal Saturn's moon
Phoebe has more planet-like qualities than previously thought.

Scientists had their first close-up look at Phoebe when Cassini began
exploring the Saturn system in 2004. Using data from multiple
spacecraft instruments and a computer model of the moon's chemistry,
geophysics and geology, scientists found Phoebe was a so-called
planetesimal, or remnant planetary building block. The findings
appear in the April issue of the Journal Icarus.

"Unlike primitive bodies such as comets, Phoebe appears to have
actively evolved for a time before it stalled out," said Julie
Castillo-Rogez, a planetary scientist at NASA's Jet Propulsion
Laboratory (JPL) in Pasadena, Calif. "Objects like Phoebe are thought
to have condensed very quickly. Hence, they represent building blocks
of planets. They give scientists clues about what conditions were
like around the time of the birth of giant planets and their moons"

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. By comparison, Saturn's large moons appear to
have formed from gas and dust around the planet's equatorial plane
and orbit 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 Phoebe 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.

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 originally may 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 remain 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 Cassini images and models, we were able to see that Phoebe
started with a nearly spherical shape, rather than 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.

The Cassini-Huygens mission is a cooperative project of NASA, the
European Space Agency and the Italian Space Agency. JPL manages the
mission for the agency's Science Mission Directorate in Washington.

CASSINI SPACECRAFT SEES NEW OBJECTS BLAZING TRAILS IN SATURN RING

FROM:  NASA
WASHINGTON -- Scientists working with images from NASA's Cassini
spacecraft have discovered strange, half-mile-sized objects punching
through one of Saturn's rings and leaving glittering trails behind
them. The results will be presented tomorrow at the European
Geosciences Union meeting in Vienna, Austria.

The penetration occurred in the outermost of Saturn's main rings,
called the F ring, which has a circumference of 550,000 miles
(881,000 kilometers). Scientists are calling the trails in the F ring
"mini-jets." Cassini scientists combed through 20,000 images and
found 500 examples of these rogues during the seven years Cassini has
been at Saturn.

"Beyond just showing us the strange beauty of the F ring, Cassini's
studies of this ring help us understand the activity that occurs when
solar systems evolve out of dusty disks that are similar to, but
obviously much grander than, the disk we see around Saturn," said
Linda Spilker, Cassini project scientist at NASA's Jet Propulsion
Laboratory (JPL) in Pasadena, Calif.

Scientists have known relatively large objects can create channels,
ripples and snowballs, or clumps of icy material, in the F ring.
However, scientists did not know what happened to these snowballs
after they were created. Some were broken up by collisions or tidal
forces in their orbit around Saturn. Scientists now have evidence
some of the smaller ones survived, and their differing orbits mean
they go on to strike through the F ring on their own.

"I think the F ring is Saturn's weirdest ring, and these latest
Cassini results go to show how the F ring is even more dynamic than
we ever thought," said Carl Murray, a Cassini imaging team member
based at Queen Mary University of London, U.K. "These findings show
us that the F ring region is like a bustling zoo of objects from a
half-mile (0.8-kilometer) in size to moons like Prometheus a hundred
miles (160.9 kilometers) in size, creating a spectacular show."

These small objects appear to collide with the F ring at gentle speeds
about 4 mph (2 meters per second). The collisions drag glittering ice
particles out of the F ring with them, leaving a trail of 20-110
miles (40-180 kilometers) long.

In some cases, the objects traveled in packs, creating mini-jets that
looked exotic, like the barb of a harpoon. Other new images show
grand views of the entire F ring and the swirls and eddies from the
different kinds of objects moving through and around it.

Saturn's rings are comprised primarily of water ice. The chunks of ice
that make up the main rings spread out 85,000 miles (140,000
kilometers) from the center of Saturn. Scientists believe the rings'
average thickness is approximately 30 feet (10 meters).

The Cassini-Huygens mission is a cooperative project of NASA, the
European Space Agency and the Italian Space Agency. JPL manages the
mission for NASA's Science Mission Directorate in Washington. The
imaging team is based at the Space Science Institute in Boulder,
Colo.

JUPITER JET STREAMS

This photo and excerpt are from the Department of Defense Armed with Science website:  
Following the path of one of Jupiter's jet streams, a line of V-shaped chevrons travels west to east just above Jupiter's Great Red Spot. Most of the planet is unfolded here in a single, flat map made on December 11 and 12, 2000, when NASA's Cassini spacecraft flew past Jupiter. At the left, the chevrons run into another storm called the South Equatorial Disturbance (SED). Credit: NASA/JPL/Space Science Institute

New movies of Jupiter are the first to catch an invisible wave shaking up one of the giant planet’s jet streams, an interaction that also takes place in Earth’s atmosphere and influences the weather.

The movies, made from images taken by NASA’s Cassini spacecraft when it flew by Jupiter in 2000, are part of an in-depth study conducted by a team of scientists and amateur astronomers led by Amy Simon-Miller at NASA’s Goddard Space Flight Center in Greenbelt, Md., and published in the April 2012 issue of Icarus.

“This is the first time anyone has actually seen direct wave motion in one of Jupiter’s jet streams,” says Simon-Miller, the paper’s lead author. “And by comparing this type of interaction in Earth’s atmosphere to what happens on a planet as radically different as Jupiter, we can learn a lot about both planets.”
Like Earth, Jupiter has several fast-moving jet streams that circle the globe. Earth’s strongest and best known jet streams are those near the north and south poles; as these winds blow west to east, they take the scenic route, wandering north and south. What sets these jet streams on their meandering paths — and sometimes makes them blast Florida and other warm places with frigid air — are their encounters with slow-moving waves in Earth’s atmosphere, called Rossby waves.

The photo at left of Jupiter is from the NASA website: 

SATURN'S TWO MOONS: TITAN AND RHEA POSE IN SPACE FOR CASSINI SPACECRAFT

“Craters appear well defined on icy Rhea in front of the hazy orb of the much larger moon Titan in this Cassini spacecraft view of these two Saturn moons. Lit terrain seen here is on the leading hemispheres of Rhea and Titan. North on the moons is up and rotated 13 degrees to the left. The limb, or edge of the visible disk, of Rhea is slightly overexposed in this view. The image was taken in visible green light with the Cassini spacecraft narrow-angle camera on Dec. 10, 2011. The view was acquired at a distance of approximately 1.2 million miles (2 million kilometers) from Titan and at a Sun-Titan-spacecraft, or phase, angle of 109 degrees. The view was acquired at a distance of approximately 810,000 miles (1.3 million kilometers) from Rhea and at a Sun-Rhea-spacecraft, or phase, angle of 109 degrees. Image scale is 8 miles (12 kilometers) per pixel on Titan and 5 miles (8 kilometers) per pixel on Rhea. Image credit: NASA/JPL-Caltech/Space Science Institute “ The above excerpt and picture are from the NASA website.