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Waspie_Dwarf

Iapetus: Saturn's Walnut-shaped Moon

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Mysterious Iapetus

May 12, 2006

A distant glimpse of Iapetus reveals details within the dark terrain of Cassini Regio, including an impact basin at top that is roughly 400 kilometers (250 miles) wide.

Researchers remain unsure about the mechanism that has darkened the leading hemisphere.

This view looks toward the southern hemisphere on the leading side of Iapetus (1,468 kilometers, or 912 miles across). North is up.

The image was taken in visible light with the Cassini spacecraft narrow-angle camera on April 4, 2006, at a distance of approximately 1.4 million kilometers (900,000 miles) from Iapetus. The image scale is 9 kilometers (6 miles) 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.

For more information about the Cassini-Huygens mission visit http://saturn.jpl.nasa.gov . The Cassini imaging team homepage is at http://ciclops.org .

Credit: NASA/JPL/Space Science Institute

Source: NASA/JPL - Cassini

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From Dark to Bright and Red to White

May 22, 2006

Cassini's landmark investigation of Saturn's yin-yang moon Iapetus, with its bright and dark hemispheres, continues to provide insights into the nature of this intriguing body.

These two views of Iapetus primarily show terrain in the southern part of the moon's dark leading hemisphere -- the side of Iapetus that is coated with dark material. The bright south pole of Iapetus is visible, along with some terrain (at the bottom) that lies on the bright trailing hemisphere.

The dark terrain known as Cassini Regio is uniformly dark between the equator and about 30 degrees south latitude. From there down to about 50 to 60 degrees south latitude, the dark material looks "patchy" because south-facing crater walls are bright (being largely devoid of the dark material). South of this region, only some northward-facing crater walls are still dark, while the bright terrain has a somewhat reddish color.

Beyond 90 degrees south (i.e., on the trailing side), the reddish color becomes white. The region at the bottom of the color view presented here shows this "color boundary" in the bright terrain, which also marks the boundary between the leading and trailing hemispheres.

Iapetus is 1,468 kilometers (912 miles) across. North is up in the monochrome image and rotated 16 degrees to the left in the color image.

The monochrome image on the left was taken using a filter sensitive to wavelengths of infrared light centered at 930 nanometers. The image was obtained with the Cassini spacecraft narrow-angle camera on April 8, 2006, at a distance of approximately 866,000 kilometers (538,000 miles) from Iapetus and at a Sun-Iapetus-spacecraft, or phase, angle of 88 degrees. The image scale is 5 kilometers (3 miles) per pixel.

The color view on the right was created by combining images taken in ultraviolet, green and infrared spectral filters. The images were acquired with the Cassini spacecraft narrow-angle camera on April 9, 2006, at a distance of approximately 692,000 kilometers (430,000 miles) from Iapetus and at a Sun-Iapetus-spacecraft, or phase, angle of 101 degrees. The image scale is 4 kilometers (2.5 miles) 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.

For more information about the Cassini-Huygens mission visit http://saturn.jpl.nasa.gov . The Cassini imaging team homepage is at http://ciclops.org .

Credit: NASA/JPL/Space Science Institute

Source: NASA/JPL - Cassini

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World of Contrast

August 2, 2006

This Cassini spacecraft view shows how the bright and dark regions on Iapetus fit together like the seams of a baseball. Some of the material that covers the moon's dark, leading side spills over into regions on the brighter trailing side, creating the feature near upper right referred to by some scientists as "the Moat."

(See Iapetus by Saturn Shine for a higher resolution view of this region.)

The large impact basin above center in the dark terrain has a diameter of about 550 kilometers (340 miles).

This view looks toward the Saturn-facing hemisphere of Iapetus (1,468 kilometers, or 912 miles across). North is up.

The image was taken in visible light with the Cassini spacecraft narrow-angle camera on June 25, 2006 at a distance of approximately 1.6 million kilometers (1 million miles) from Iapetus. Image scale is 9 kilometers (6 miles) 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.

For more information about the Cassini-Huygens mission visit http://saturn.jpl.nasa.gov . The Cassini imaging team homepage is at http://ciclops.org .

Credit: NASA/JPL/Space Science Institute

Source: NASA/JPL - Cassini

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Duotone Moon

September 25, 2006

The many impact scars borne by Iapetus are made far more conspicuous in the region of transition from its dark hemisphere to its bright one. In this terrain, the dark material that coats Cassini Regio accentuates slopes and crater floors, creating a land of stark contrasts.

North on Iapetus (1,468 kilometers, or 912 miles across) is up.

The image was taken in visible light with the Cassini spacecraft narrow-angle camera on Sept. 6, 2006 at a distance of approximately 2.2 million kilometers (1.4 million miles) from Iapetus and at a Sun- Iapetus-spacecraft, or phase, angle of 26 degrees. Image scale is 13 kilometers (8 miles) 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.

For more information about the Cassini-Huygens mission visit http://saturn.jpl.nasa.gov . The Cassini imaging team homepage is at http://ciclops.org .

Credit: NASA/JPL/Space Science Institute

Source: NASA/JPL - Cassini

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Brightside in View

January 5, 2007

The Cassini spacecraft continues to image terrain on Iapetus that is progressively eastward of the terrain it has previously seen illuminated by sunlight.

The region seen here was imaged in reflected light from Saturn at excellent resolution in the close flyby on New Year's Eve 2004 (see Iapetus by Saturn Shine).

This view looks toward the equator of Iapetus (1,468 kilometers, or 912 miles across) on the moon's Saturn-facing side. North is up and rotated 11 degrees to the right.

The image was taken in visible green light with the Cassini spacecraft narrow-angle camera on Nov. 27, 2006 at a distance of approximately 2 million kilometers (1.2 million miles) from Iapetus. Image scale is 12 kilometers (7 miles) 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.

For more information about the Cassini-Huygens mission visit http://saturn.jpl.nasa.gov . The Cassini imaging team homepage is at http://ciclops.org .

Credit: NASA/JPL/Space Science Institute

Source: NASA/JPL - Cassini

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Cloaking Iapetus

March 22, 2007

Darkness sweeps over Iapetus as the Cassini spacecraft watches the shadow of Saturn's B ring engulf the dichotomous moon. The image at left shows the unshaded moon, while at right, Iapetus sits in the shadow of the densest of Saturn's rings.

North on Iapetus (1,468 kilometers, or 912 miles across) is up and rotated eight degrees to the left.

The images were taken in visible light with the Cassini spacecraft narrow-angle camera on Feb. 13, 2007 at a distance of approximately 2.3 million kilometers (1.4 million miles) from Iapetus. Image scale is 14 kilometers (8 miles) 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.

For more information about the Cassini-Huygens mission visit http://saturn.jpl.nasa.gov . The Cassini imaging team homepage is at http://ciclops.org .

Credit: NASA/JPL/Space Science Institute

Source: NASA/JPL - Cassini

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On the Bright Side

May 29, 2007

The Cassini spacecraft views terrain on the bright, trailing side of Iapetus in natural color. This side of Iapetus starkly contrasts with the much darker leading hemisphere, and some of the dark material seen here in association with craters near the terminator is an extension of the leading hemisphere terrain.

This region was previously imaged by the spacecraft at a much finer resolution -- a spatial scale of less than 1 kilometer (0.6 miles) per pixel -- during a flyby at the close of 2004. This terrain was then on the moon's night side at the time, and Cassini imaged it using weak, reflected light from Saturn (see Iapetus by Saturn Shine).

The present view looks toward Iapetus (1,468 kilometers, or 912 miles across) from about 24 degrees above the moon's equator.

Images taken using red, green and blue spectral filters were combined to create this natural color view. The images were taken with the Cassini spacecraft narrow-angle camera on April 15, 2007 at a distance of approximately 2.3 million kilometers (1.4 million miles) from Iapetus and at a Sun-Iapetus-spacecraft, or phase, angle of 66 degrees. Scale in the original images is 13 kilometers (8 miles) per pixel. The view has been magnified by a factor of three.

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.

For more information about the Cassini-Huygens mission visit http://saturn.jpl.nasa.gov. The Cassini imaging team homepage is at http://ciclops.org.

Credit: NASA/JPL/Space Science Institute

Source: NASA/JPL - Cassini

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Saturn's Old Moon Iapetus Retains its Youthful Figure


July 17, 2007
(Source: Jet Propulsion Laboratory)

Saturn's distinctive moon Iapetus (eye-APP-eh-tuss) is cryogenically frozen in the equivalent of its teenage years. The moon has retained the youthful figure and bulging waistline it sported more than three billion years ago, scientists report.

"Iapetus spun fast, froze young, and left behind a body with lasting curves," said Julie Castillo, Cassini scientist at NASA's Jet Propulsion Laboratory, Pasadena, Calif.

linked-image
Unlike any other moon in the solar system,
Iapetus is the same shape today as it was when
it was just a few hundred million years old.


Unlike any other moon in the solar system, Iapetus is the same shape today as it was when it was just a few hundred million years old; a well-preserved relic from the time when the solar system was young. These results appear in the online version of the journal Icarus.

Cassini flew by Iapetus in early 2005 and discovered the moon had a walnut shape, bulging at its midsection. On top of that it has a chain of mountains located exactly along its equator.

Scientists now think the moon's bulging midriff and slow spin rate point to heating from long-extinct radioactive elements present when the solar system was born.

"We've modeled how Iapetus formed its big, spin-generated bulge and why its rotation slowed down to its present nearly 80-day period. As an unexpected bonus, Iapetus also told us how old it was," said Dennis Matson, Cassini project scientist at JPL. "You would expect a very fast-spinning moon to have this bulge, but not a slow-spinning moon, because the bulge would have been much flatter."

Scientists calculate Iapetus originally rotated much faster -- at least five hours, but less than 16 hours per revolution. The fast spin gave the moon an oblate shape that increased the surface area (in the same way the surface area of a round balloon stretches when the balloon is pressed into an oblate shape). By the time the rotation slowed down to a period of 16 hours, the outer shell of the moon had frozen. Furthermore, the surface area of the cold moon was now smaller. The excess surface material was too rigid to go back smoothly into the moon. Instead, it piled up in a chain of mountains at the equator.

"Iapetus' development literally stopped in its tracks," said Castillo. "In order for tidal forces to slow Iapetus to its current spin rate, its interior had to be much warmer, close to the melting point for water ice." The challenge in developing a model of how Iapetus came to be "frozen in time" has been in deducing how it ever became warm enough to form a bulge in the first place, and figuring out what caused the heat source to turn off, leaving Iapetus to freeze.

The heat source had to have a limited life span, to allow the moon's crust to rapidly become cold and retain its immature shape. After looking at several models, scientists concluded that the heat came from its rocks, which contain short-lived radioactive isotopes aluminum-26 and iron-60 (which decay very rapidly on a geologic timescale). Since these elements decay at a known rate, this allowed scientists to "carbon date" Iapetus by using aluminum-26 instead of carbon. Scientists calculate the age of Iapetus to be roughly 4.564 billion years old.

Evidence for these same isotopes (aluminum-26 and iron-60) has been found in meteorites formed in the inner solar system. Therefore, there is a possibility of comparing the early chronology of the outer solar system with other objects in the inner solar system, such as Earth, Earth's moon and asteroids.

"This is the first direct evidence of the early spin history for a satellite in the outer solar system. It teaches us more about how the speed of a body's rotation influenced its evolution, and broadens our knowledge of the early history of outer planet satellites," said Matson.

Cassini's next close encounter with Iapetus will occur on Sept. 10, 2007, at 1,000 kilometers (620 miles) from the surface.

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

More information on the Cassini mission is available at: http://www.nasa.gov/cassini.

Contacts:
Carolina Martinez 818-354-9382
Jet Propulsion Laboratory, Pasadena, Calif.


NEWS RELEASE: 2007-079


Source: NASA/JPL - Cassini - Press Release

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Unveiling Iapetus

August 21, 2007

As the Cassini spacecraft sets up for its September 2007 close encounter with the two-toned moon Iapetus, the spacecraft is seeing more of the moon's bright, trailing hemisphere. This is a region Cassini has seen relatively little of until recently. The September encounter will provide high resolution images of this region, including the large crater seen here at about the five o'clock position.

North on Iapetus (1,468 kilometers, or 912 miles across) is up and rotated about 5 degrees to the right.

The image was taken using a spectral filter sensitive to wavelengths of ultraviolet light centered at 338 nanometers. The view was acquired with the Cassini spacecraft narrow-angle camera on July 3, 2007. The view was acquired at a distance of approximately 2.2 million kilometers (1.4 million miles) from Iapetus and at a Sun-Iapetus-spacecraft, or phase, angle of 53 degrees. Image scale is 13 kilometers (8 miles) 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.

For more information about the Cassini-Huygens mission visit http://saturn.jpl.nasa.gov. The Cassini imaging team homepage is at http://ciclops.org.

Credit: NASA/JPL/Space Science Institute

Source: NASA/JPL - Cassini

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Cassini Prepares to Fly By Walnut-shaped Moon


September 5, 2007
(Source: Jet Propulsion Laboratory)

PASADENA, Calif. - Cassini will make its only close flyby of Saturn's odd, two-toned, walnut-shaped moon Iapetus on Sept. 10, 2007, at about 1,640 kilometers (1,000 miles) from the surface.

This flyby will be 100 times closer than Cassini's 2004 encounter, and will be the last time the spacecraft will aim its instruments at this moon.

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Images taken with Cassini's ultraviolet imaging
spectrograph shed some light on the dark side
of Saturn's moon Iapetus. Scientists are trying
to figure out what painted Iapetus' dark side.

--------------------------------------------------------------------------------


Iapetus (pronounced eye-APP-eh-tuss) has a ridge of surprisingly large mountains -- the so-called "belly-band" -- that lies directly on top of the equator. The moon also has a distinct difference in the brightness of its leading and trailing hemispheres, one as bright as snow and the other dark as tar. The irregular shape, the mountain ridge and Iapetus' brightness contrast are among the key mysteries scientists are trying to solve.

There are several different ideas on the origin of the dark material. Is it from inside or outside of Iapetus? Is it residue from some other moon or moons? Is it due to impacts by meteoroids or comet debris?

"We are on the search for the brush that may have painted Iapetus's dark side," said Dennis Matson, Cassini project scientist at NASA's Jet Propulsion Laboratory, Pasadena, Calif.

linked-image
This map of the surface of Iapetus, generated
from images taken by NASA's Cassini and
Voyager spacecraft, illustrates the imaging
coverage planned for Cassini's very close
flyby of the two-toned moon on Sept. 10,
2007.

--------------------------------------------------------------------------------


"This dark stuff appears in several places in the Saturn system and might be present not just on Iapetus but many other moons," said JPL scientist Amanda Hendrix of Cassini's ultraviolet imaging spectrograph team and lead author of a paper soon to be published in the journal Icarus that explores the possible sources of the Iapetus dark material.

There's a reddish tint to the Iapetus dark stuff, an important clue in tracing its origin, she said. Saturn's moon Hyperion, which shows evidence of a violent disruption in its past, has a reddish tint, too. "It may be that the event that disrupted Hyperion deposited reddish material onto Iapetus," she said. "Hyperion may be the artist that's painting Iapetus dark."

Yet another Icarus paper on Iapetus by Dale Cruikshank at NASA's Ames Research Center, Moffett Field, Calif., and colleagues, reports that the dark material on Iapetus and Saturn's small moon Phoebe may be composed of the same complex, prebiotic hydrocarbons that appear to play a fundamental role in the origin of life. These chemicals, called polycyclic aromatic hydrocarbons, exist on objects ranging from backyard barbeques to comets, meteorites and the stardust that forms planets and flows between stars. They are important markers in studies of the origin of life in the universe.

An array of Cassini instruments will home in on Iapetus during the flyby. The full menu of objectives includes plans to: characterize the chemical composition of the surface; look for evidence of a faint atmosphere or erupting gas plumes; and map the nighttime temperature of the surface. This will be the first Cassini flyby of an icy moon, other than Titan, that's close enough and slow enough to perform radar imaging with Cassini's Synthetic Aperture Radar. A large swath of terrain will be covered, including the equatorial ridge and regions of craters and basins. These measurements may provide the height of some of the features.

"What is really neat is that we are doing radar of an icy object for which we actually have pictures," said Steve Ostro, a radar scientist at JPL. Until now, he said, the radar had been used to reveal the surface of cloud-covered Titan. Iapetus' surface is easily visible. "This will be a lesson on how to interpret radar images on an icy body. With Titan, because of the cloud cover, we don't know what we are looking at much of the time, but for Iapetus we will know very well," he said. In coming weeks, scientists will be analyzing data from multiple instruments. Some results of that analysis will be presented at a planetary science conference in Orlando, Fla., in mid-October.

More information on the Cassini-Huygens mission is available at: http://saturn.jpl.nasa.gov and http://www.nasa.gov/cassini .

The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. JPL, a division of the California Institute of Technology in Pasadena, manages the Cassini mission for NASA's Science Mission Directorate, Washington, D.C. JPL designed, developed and assembled the Cassini orbiter.

Contacts:
Carolina Martinez 818-354-9382
Jet Propulsion Laboratory, Pasadena, Calif.
carolina.martinez@jpl.nasa.gov

NEWS RELEASE: 2007-096

Source: NASA/JPL - Cassini - News Release

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Exposing Iapetus' Dark Side

September 6, 2007

Images taken with Cassini's ultraviolet imaging spectrograph shed some light on the dark side of Saturn's moon Iapetus. Scientists are trying to figure out what painted Iapetus' dark side. This is one of the biggest mysteries scientists are trying to answer during the upcoming Sept. 10, 2007, flyby.

The ultraviolet image on the left indicates water ice abundance across the surface: the bright north polar terrain (shown in red) is the iciest region in this view. Away from the pole, as the color shifts to blue, less water ice is present in the surface. The darkest terrain, which includes very little water ice, is shown in light blue. The dark sky background viewed during the observation is shown as purple in this color scheme.

The ultraviolet-light image was taken during a flyby in December 2004. A visible light image taken on the same date is shown on the right for reference (see Encountering Iapetus).

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 was designed, developed and assembled at JPL. The ultraviolet imaging spectrograph was designed and built at, and the team is based at the University of Colorado, Boulder. The imaging operations center is based at the Space Science Institute in Boulder, Colo. For more information about the Cassini-Huygens mission visit http://saturn.jpl.nasa.gov/home/index.cfm. The ultraviolet imaging spectrograph team home page is at http://lasp.colorado.edu/cassini. The Cassini imaging team homepage is at http://ciclops.org.

Credit: NASA/JPL/University of Colorado/Space Science Institute

Source: NASA/JPL - Cassini

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Eyes on Iapetus!

September 6, 2007

This map of the surface of Iapetus, generated from images taken by NASA's Cassini and Voyager spacecraft, illustrates the imaging coverage planned for Cassini's very close flyby of the two-toned moon on Sept. 10, 2007. This flyby will be Cassini's only close approach to Iapetus (1,468 kilometers, or 912 miles across) during the entire planned mission.

At closest approach, Cassini will be 1,640 kilometers (1,020 miles) above the surface of Iapetus. The spacecraft will pass the moon at a speed of about 2.4 kilometers (1.5 miles) per second--a relatively leisurely pace that will allow plenty of time for the scientific instruments on board to collect massive amounts of data.

Cassini's previous encounter with Iapetus, on Dec. 31, 2004, focused on the mysterious territory in Cassini Regio, the region blanketed by dark material that covers most of the moon's leading hemisphere. The upcoming encounter will be primarily concerned with terrain farther west, in the important transition region between Cassini Regio and the bright trailing hemisphere. Scientists hope to learn a great deal more about the composition of the materials that compose the surface of Iapetus during this encounter.

Another area of focus is the large equatorial ridge that overlies the moon's equator (see Encountering Iapetus). The ridge reaches 20 kilometers (12 miles) high in some places and extends over 1,300 kilometers (808 miles) in length. No other moon in the solar system has a geological feature like this striking ridge. The tallest mountains on the ridge rival Olympus Mons on Mars, which is approximately three times the height of Mt. Everest. Such giant mountains are a surprising feature for such a small body as Iapetus, which is nearly five times smaller than Mars and nearly nine times smaller than Earth.

Colored lines on the map enclose regions that will be covered at different imaging scales as Cassini encounters Iapetus. The highest expected resolution of Cassini images from this flyby is about 20 meters (65 feet) per pixel--significantly higher than the 2004 encounter.

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.

For more information about the Cassini-Huygens mission visit http://saturn.jpl.nasa.gov. The Cassini imaging team homepage is at http://ciclops.org.

Credit: NASA/JPL/Space Science Institute

Source: NASA/JPL - Cassini

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Surface of Iapetus

09.11.07

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This is a raw, or unprocessed, image taken by the Cassini spacecraft during its close flyby of Saturn's moon Iapetus on September 10.

For more information about the Cassini-Huygens mission visit http://saturn.jpl.nasa.gov. The Cassini imaging team homepage is at http://ciclops.org.

Credit: Image credit: NASA/JPL/Space Science Institute

+ Full resolution (117Kb)

Source: NASA - Missions - Cassini

Edited by Waspie_Dwarf

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Saturn's Moon Iapetus

09.11.07

linked-image

This is a raw, or unprocessed, image taken by the Cassini spacecraft during its close flyby of Saturn's moon Iapetus on September 10.

For more information about the Cassini-Huygens mission visit http://saturn.jpl.nasa.gov. The Cassini imaging team homepage is at http://ciclops.org.

Credit: Image credit: NASA/JPL/Space Science Institute

+ Full resolution (159Kb)

Source: NASA - Missions - Cassini

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Cassini Mission Status: Cassini Flies by Walnut-Shaped Moon Iapetus

09.11.07

Cassini completed its closest flyby of the odd moon Iapetus on Sept. 10, 2007. The spacecraft flew about 1,640 kilometers (1,000 miles) from Iapetus' surface and is returning amazing views of the bizarre moon.

linked-image

Image above: Saturn's moon Iapetus.

Image credit: NASA/JPL/Space Science Institute

+ Full image and caption

All the data were successfully recorded on the spacecraft. Twenty-one minutes into the first post-flyby data downlink, the spacecraft went into a precautionary condition called safe mode. The cause has been determined to be a solid state power switch that was tripped due to a galactic cosmic ray hit.

While in safe mode, the spacecraft turns off all unnecessary activities and transmits only essential engineering telemetry at a low data rate, while it awaits commands from Earth.

linked-image

Image above: Saturn's moon Iapetus.

Image credit: NASA/JPL/Space Science Institute

+ Full image and caption

Tuesday morning, Sept. 11, commands were sent to the spacecraft to resume high rate science and engineering data playback. The project expects all data on the spacecraft will be returned to Earth during downlinks on Tuesday and Wednesday, with no impact on the Iapetus science data return beyond a brief delay.

Due to the safing event, the sequence executing on the spacecraft was halted, and Cassini's instruments will not be turned back on for three or four days. The last time Cassini was in safe mode was over four years ago.

Media contact: Carolina Martinez 818-354-9382

Jet Propulsion Laboratory, Pasadena, Calif.

Source: NASA - Missions - Cassini - Media

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Close-Up of Iapetus

09.11.07

linked-image

This is a raw, or unprocessed, image taken by the Cassini spacecraft during its close flyby of Saturn's moon Iapetus on September 10.

For more information about the Cassini-Huygens mission visit http://saturn.jpl.nasa.gov. The Cassini imaging team homepage is at http://ciclops.org.

Credit: Image credit: NASA/JPL/Space Science Institute

+ Full resolution (272Kb)

Source: NASA - Missions - Cassini

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Close-Up of Iapetus

09.12.07

linked-image

This is a raw, or unprocessed, image taken by the Cassini spacecraft during its close flyby of Saturn's moon Iapetus on September 10.

For more information about the Cassini-Huygens mission visit http://saturn.jpl.nasa.gov. The Cassini imaging team homepage is at http://ciclops.org.

Credit: Image credit: NASA/JPL/Space Science Institute

+ Full resolution

Source: NASA - Missions - Cassini

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Close-Up of Iapetus

09.12.07

linked-image

This is a raw, or unprocessed, image taken by the Cassini spacecraft during its close flyby of Saturn's moon Iapetus on September 10.

For more information about the Cassini-Huygens mission visit http://saturn.jpl.nasa.gov. The Cassini imaging team homepage is at http://ciclops.org.

Credit: Image credit: NASA/JPL/Space Science Institute

+ Full resolution

Source: NASA - Missions - Cassini

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Close-Up of Iapetus

09.12.07

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This is a raw, or unprocessed, image taken by the Cassini spacecraft during its close flyby of Saturn's moon Iapetus on September 10.

For more information about the Cassini-Huygens mission visit http://saturn.jpl.nasa.gov. The Cassini imaging team homepage is at http://ciclops.org.

Credit: Image credit: NASA/JPL/Space Science Institute

Source: NASA - Missions - Cassini

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The Himalayas of Iapetus

September 12, 2007

This stunning close-up view shows mountainous terrain that reaches about 10 kilometers (6 miles) high along the unique equatorial ridge of Iapetus. The view was acquired during Cassini's only close flyby of the two-toned Saturn moon.

Above the middle of the image can be seen a place where an impact has exposed the bright ice beneath the dark overlying material.

The image was taken on Sept. 10, 2007, with the Cassini spacecraft narrow-angle camera at a distance of approximately 3,870 kilometers (2,400 miles) from Iapetus. Image scale is 23 meters (75 feet) 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.

For more information about the Cassini-Huygens mission visit http://saturn.jpl.nasa.gov. The Cassini imaging team homepage is at http://ciclops.org.

Credit: NASA/JPL/Space Science Institute

Source: NASA/JPL - Cassini

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Inky Stains on a Frozen Moon

September 12, 2007

Dark material splatters the walls and floors of craters in the surreal, frozen wastelands of Iapetus. This image shows terrain in the transition region between the moon's dark leading hemisphere and its bright trailing hemisphere. The view was acquired during Cassini's only close flyby of the two-toned Saturn moon.

The image was taken on Sept. 10, 2007, with the Cassini spacecraft narrow-angle camera at a distance of approximately 6,030 kilometers (3,750 miles) from Iapetus. Image scale is 36 meters (118 feet) 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.

For more information about the Cassini-Huygens mission visit http://saturn.jpl.nasa.gov. The Cassini imaging team homepage is at http://ciclops.org.

Credit: NASA/JPL/Space Science Institute

Source: NASA/JPL - Cassini

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Saturn's Moon Iapetus Is the Yin-and-Yang of the Solar System

09.12.07

PASADENA, Calif. - Scientists on the Cassini mission to Saturn are poring through hundreds of images returned from the Sept. 10 flyby of Saturn's two-toned moon Iapetus. Pictures returned late Tuesday and early Wednesday show the moon's yin and yang--a white hemisphere resembling snow, and the other as black as tar.

Images show a surface that is heavily cratered, along with the mountain ridge that runs along the moon's equator. Many of the close-up observations focused on studying the strange 20-kilometer high (12 mile) mountain ridge that gives the moon a walnut-shaped appearance.

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Image above: Cassini surveys a bright landscape coated by dark material

on Iapetus. This image shows terrain in the transition region between the

moon’s dark leading hemisphere and its bright trailing hemisphere.

Image credit: NASA/JPL/Space Science Institute

"The images are really stunning," said Tilmann Denk, Cassini imaging scientist at the Free University in Berlin, Germany, who was responsible for the imaging observation planning. "Every new picture contained its own charm. I was most pleased about the images showing huge mountains rising over the horizon. I knew about this scenic viewing opportunity for more than seven years, and now the real images suddenly materialized."

This flyby was nearly 100 times closer to Iapetus than Cassini's 2004 flyby, bringing the spacecraft to about 1,640 kilometers (1,000 miles) from the surface. The moon's irregular walnut shape, the mountain ridge that lies almost directly on the equator and Iapetus' brightness contrast are among the key mysteries scientists are trying to solve.

"There's never a dull moment on this mission," said Bob Mitchell, Cassini program manager, NASA's Jet Propulsion Laboratory, Pasadena, Calif. "We are very excited about the stunning images being returned. There's plenty here to keep many scientists busy for many years."

"Our flight over the surface of Iapetus was like a non-stop free fall, down the rabbit hole, directly into Wonderland! Very few places in our solar system are more bizarre than the patchwork of pitch dark and snowy bright we've seen on this moon," said Carolyn Porco, Cassini imaging team leader at the Space Science Institute, Boulder, Colo.

linked-image

Image above: This stunning close-up view

shows mountainous terrain that reaches about

10 kilometers (6 miles) high along the unique

equatorial ridge of Iapetus.

Image credit: NASA/JPL/Space Science Institute

The return of images and other data was delayed early Tuesday due to a galactic cosmic ray hit which put the spacecraft into a precautionary state called safe mode. This occurred after the spacecraft had placed all of the flyby data on its data recorders and during the first few minutes after it began sending the data home. The data flow resumed later that day and concluded on Wednesday. The spacecraft is operating normally and its instruments are expected to return to normal operations in a few days.

"Iapetus provides us a window back in time, to the formation of the planets over four billion years ago. Since then its icy crust has been cold and stiff, preserving this ancient surface for our study," said Torrence Johnson, Cassini imaging team member at JPL.

Cassini's multiple observations of Iapetus will help to characterize the chemical composition of the surface; look for evidence of a faint atmosphere or erupting gas plumes; and map the nighttime temperature of the surface. These and other results will be analyzed in the weeks to come.

Iapetus flyby images are available at: http://www.nasa.gov/cassini and http://saturn.jpl.nasa.gov and and http://ciclops.org.

The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. JPL, a division of the California Institute of Technology in Pasadena, manages the Cassini 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 team is based at the Space Science Institute, Boulder, Colo.

Media contact: Carolina Martinez 818-354-9382

Jet Propulsion Laboratory, Pasadena, Calif.

carolina.martinez@jpl.nasa.gov

Preston Dyches 720-974-5859

Space Science Institute, Boulder, Colo.

media@ciclops.org

2007-101

Source: NASA - Missions - Cassini - Media

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Coated Craters

09.12.07

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Cassini surveys a bright landscape coated by dark material on Iapetus. This image shows terrain in the transition region between the moon’s dark leading hemisphere and its bright trailing hemisphere. The view was acquired during Cassini's only close flyby of the two-toned Saturn moon.

The image was taken on Sept. 10, 2007, with the Cassini spacecraft narrow-angle camera at a distance of approximately 5,260 kilometers (3,270 miles) from Iapetus. Image scale is 32 meters (105 feet) 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.

For more information about the Cassini-Huygens mission visit http://saturn.jpl.nasa.gov. The Cassini imaging team homepage is at http://ciclops.org.

Credit: Image credit: NASA/JPL/Space Science Institute

+ High resolution

Source: NASA - Missions - Cassini

Edited by Waspie_Dwarf

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The "Voyager" Mountains

09.12.07

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Cassini zooms in, for the first time, on the patchy, bright and dark mountains originally identified in images from the NASA Voyager spacecraft taken more than 25 years earlier. The image was acquired during Cassini's only close flyby of Iapetus, a two-toned moon of Saturn.

The terrain seen here is located on the equator of Iapetus at approximately 199 degrees west longitude, in the transition region between the moon's bright and dark hemispheres. North is up.

The image was taken on Sept. 10, 2007, with the Cassini spacecraft narrow-angle camera at a distance of approximately 9,240 kilometers (5,740 miles) from Iapetus. Image scale is 55 meters (180 feet) per pixell.

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.

For more information about the Cassini-Huygens mission visit http://saturn.jpl.nasa.gov. The Cassini imaging team homepage is at http://ciclops.org.

Credit: Image credit: NASA/JPL/Space Science Institute

+ High resolution

Source: NASA - Missions - Cassini

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Cassini Is on the Trail of a Runaway Mystery

10.08.07

NASA scientists are on the trail of Iapetus' mysterious dark side, which seems to be home to a bizarre "runaway" process that is transporting vaporized water ice from the dark areas to the white areas of the Saturnian moon.

This "thermal segregation" model may explain many details of the moon's strange and dramatically two-toned appearance, which have been revealed exquisitely in images collected during a recent close flyby of Iapetus by NASA's Cassini spacecraft.

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Image above: Cassini captures the first high-resolution glimpse of the

bright trailing hemisphere of Saturn's moon Iapetus in this false-color

mosaic. This false-color mosaic shows the entire hemisphere of Iapetus.

Image credit: NASA/JPL/Space Science Institute

Infrared observations from the flyby confirm that the dark material is warm enough (approximately minus 230 degrees Fahrenheit or 127 Kelvin) for very slow release of water vapor from water ice, and this process is probably a major factor in determining the distinct brightness boundaries.

"The side of Iapetus that faces forward in its orbit around Saturn is being darkened by some mysterious process," said John Spencer, Cassini scientist with the composite infrared spectrometer team from the Southwest Research Institute, Boulder, Colo.

Using multiple instruments on Cassini, scientists are piecing together a complex story to explain the bright and dark faces of Iapetus. But yet to be fully understood is where the dark material is coming from. Is it native or from outside the moon? It has long been hypothesized that this material did not originate from within Iapetus, but instead was derived from other moons orbiting at a much greater distance from Saturn in a direction opposite to Iapetus.

Scientists are now converging on the notion that the darkening process in fact began in this manner, and that thermal effects subsequently enhanced the contrast to what we see today.

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Image above: This image compares midday

temperatures on Saturn's moon Iapetus,

recorded by the composite infrared spectrometer

instrument during Cassini's close Sept. 10, 2007

flyby, with images of the same region recorded

during the same flyby by the Cassini imaging

science subsystem.

Image credit: NASA/JPL/GSFC/SwRI/SSI

"It's interesting to ponder that a more than 30-year-old idea might still help explain the brightness difference on Iapetus," said Tilmann Denk, Cassini imaging scientist at the Free University in Berlin, Germany. "Dusty material spiraling in from outer moons hits Iapetus head-on, and causes the forward-facing side of Iapetus to look different than the rest of the moon."

Once the leading side is even slightly dark, thermal segregation can proceed rapidly. A dark surface will absorb more sunlight and warm up, explains Spencer, so the water ice on the surface evaporates. The water vapor then condenses on the nearest cold spot, which could be Iapetus's poles, and possibly bright, icy areas at lower latitudes on the side of the moon facing in the opposite direction of its orbit. So the dark stuff loses its surface ice and gets darker, and the bright stuff accumulates ice and gets brighter, in a runaway process.

Scientists say the result is that there are virtually no shades of gray on Iapetus. There is only white and very dark.

Ultraviolet data also show a non-ice component in the bright, white regions of Iapetus. Spectroscopic analysis will reveal whether the composition of the material on the dark hemisphere is the same as the dark material that is present within the bright terrain.

"The ultraviolet data tell us a lot about where the water ice is and where the non-water ice stuff is. At first glance, the two populations do not appear to be present in the pattern we expected, which is very interesting," said Amanda Hendrix, Cassini scientist on the ultraviolet imaging spectrograph team at NASA's Jet Propulsion Laboratory, Pasadena, Calif.

Because of the presence of very small craters that excavate the bright ice beneath, scientists also believe that the dark material is thin, a result consistent with previous Cassini radar results. But some local areas may be thicker. The dark material seems to lie on top of the bright region, consistent with the idea that it is a residual left behind by the sublimated water ice.

Some other mysteries are coming together. There are more data on the signature mountain ridge that gives Iapetus its "walnut" appearance. In some places it appears subdued. One big question that remains is why it does not go all the way around. Was it partially destroyed after it formed, or did it never extend all the way around the moon? Scientists have ruled out that it is a youthful feature because it is pitted with craters, indicating it is old. And the ridge looks too solid and competent to be the result of an equatorial ring around the moon collapsing onto its surface. The ring theory cannot explain features that look like tectonic structures in the new high resolution images.

Over the next few months, scientists hope to learn more about Iapetus' mysteries.

New Iapetus images, temperature maps and other visuals on Iapetus are available at: http://www.nasa.gov/cassini and http://saturn.jpl.nasa.gov.

The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. JPL, a division of the California Institute of Technology in Pasadena, manages the Cassini mission for NASA's Science Mission Directorate, Washington, D.C.

Media contact: Carolina Martinez 818-354-9382

Jet Propulsion Laboratory, Pasadena, Calif.

carolina.martinez@jpl.nasa.gov

2007-113

Source: NASA - Missions - Cassini - Media

Edited by Waspie_Dwarf

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