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As it swooped past the south pole of Saturn's moon Enceladus on July 14, 2005, Cassini acquired high resolution views of this puzzling ice world. From afar, Enceladus exhibits a bizarre mixture of softened craters and complex, fractured terrains.
This large mosaic of 21 narrow-angle camera images have been arranged to provide a full-disk view of the anti-Saturn hemisphere on Enceladus. This mosaic is a false-colour view that includes images taken at wavelengths from the ultraviolet to the infrared portion of the spectrum, and is similar to another, lower resolution false-colour view obtained during the flyby. In false-colour, many long fractures on Enceladus exhibit a pronounced difference in colour (represented here in blue) from the surrounding terrain.


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A leading explanation for the difference in colour is that the walls of the fractures expose outcrops of coarse-grained ice that are free of the powdery surface materials that mantle flat-lying surfaces.
The original images in the false-colour mosaic range in resolution from 350 to 67 meters per pixel and were taken at distances ranging from 61,300 to 11,100 kilometres from Enceladus. The mosaic is also part of a movie sequence of images from this flyby.


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From New Scientist:

Bizarre boulders on Enceladus surface:

On 14 July, Cassini swooped in for an unprecedented close-up view of the wrinkled moon. Its Imaging Science Subsystem (ISS) camera has since returned pictures of a boulder-strewn landscape that is currently beyond explanation. The "boulders" appear to range between 10 and 20 metres in diameter in the highest-resolution images, which can resolve features just 4 m across.

“That’s a surface texture I have never seen anywhere else in the solar system,” says David Rothery, a planetary geologist at the Open University in Milton Keynes, UK.

Cracks crisscross Enceladus's surface - possibly as a result of the moon being repeatedly squeezed and stretched by the gravity of Saturn and other moons nearby. But Rothery points out the boulders avoid - rather than fill - the cracks. This might indicate that the fracturing took place after the boulders had already formed.
Alien landscape

John Spencer, a Cassini team member at the Southwest Research Institute in Boulder, Colorado, US, agrees that the images are puzzling. “You would expect to see small craters or a smooth, snow-covered landscape at this resolution," he told New Scientist. "This is just strange. In fact, I have a really hard time understanding what I’m seeing.”

NASA scientists have been locked in discussions since 15 July and are expected to pass judgment on what they think this peculiar surface might be later on Tuesday.

But Elizabeth Turtle, a Cassini imaging team member at the University of Arizona in Tucson, US, warns there will be no quick answers. “Trying to figure out what is going on is going to take a lot longer than a weekend of swapped emails,” she says.

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This image was taken with the narrow angle camera from a distance of approximately 68,320 kilometres from Enceladus and at a Sun-Enceladus-spacecraft, or phase, angle of 50 degrees. Resolution in the image is about 410 metres per pixel.



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This image was taken on July 14, 2005 and received on Earth July 15, 2005. The camera was approximately 35,276 kilometres away from the surface.
The image was taken using the CL1 and CL2 filters.


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This image was taken with the narrow angle camera from a distance of approximately 24,380 kilometres from Enceladus and at a Sun-Enceladus-spacecraft, or phase, angle of 50 degrees. Resolution in the image is about 290 metres per pixel.




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This image was taken with the narrow angle camera from a distance of approximately 33,610 kilometres from Enceladus and at a Sun-Enceladus-spacecraft, or phase, angle of 50 degrees. Resolution in the image is about 200 metres per pixel.







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These images were taken on Jul 15, 2005


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This image was taken with the narrow angle camera from a distance of approximately 103,230 kilometres from Enceladus and at a Sun-Enceladus-spacecraft, or phase, angle of 50 degrees. Resolution in the image is about 610 metres per pixel.


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The image was taken with the narrow angle camera from a distance of approximately 34,640 kilometres from Enceladus and at a Sun-Enceladus-spacecraft, or phase, angle of 50 degrees. Resolution in the image is about 210 metres per pixel.


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This image was taken with the narrow angle camera from a distance of approximately 22,710 kilometres from Enceladus and at a Sun-Enceladus-spacecraft, or phase, angle of 50 degrees. Resolution in the image is about 130 metres per pixel.



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This image was taken with the narrow angle camera from a distance of approximately 18,600 kilometres from Enceladus and at a Sun-Enceladus-spacecraft, or phase, angle of 50 degrees. Resolution in the image is about 110 metres per pixel.


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This image was taken with the narrow angle camera from a distance of approximately 19,330 kilometres from Enceladus and at a Sun-Enceladus-spacecraft, or phase, angle of 50 degrees. Resolution in the image is about 230 metres per pixel.


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This image was taken with the narrow angle camera from a distance of approximately 16,080 kilometres from Enceladus and at a Sun-Enceladus-spacecraft, or phase, angle of 50 degrees. Resolution in the image is about 190 metres per pixel.


-- Edited by Blobrana at 12:58, 2005-07-16

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This is the first raw image returned from the Cassini spacecraft after its closest flyby yet, on July 14. Here the surface of Enceladus is about 320 kilometres away.






This image was taken on July 14, 2005 and received on Earth July 15, 2005. The camera was pointing toward Enceladus that was approximately 545 kilometres away. The image was taken using the CL1 and CL2 filters.


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This map of the surface of Enceladus illustrates the regions that will be imaged by NASA's Cassini spacecraft during its planned very close flyby on July 14, 2005.
At closest approach, the spacecraft is expected to pass approximately 175 kilometres above the moon's surface.
This is less than half the distance of Cassini's previous encounter with Enceladus (505 kilometres across), in March of this year.
The coloured lines delineate the regions that will be imaged at the range of resolutions listed in the legend below.


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An important scientific goal of this close flyby, during which Cassini will view the moon's previously unseen south pole, will be to search for evidence of geologically recent tectonic or volcanic activity.
During the March 2005 Enceladus flyby, Cassini revealed fractures at southern latitudes, which have intriguing spectral differences from the surrounding terrain. This possibly indicates the presence of coarse-grained ice on the walls of geologically recent, large cracks in the surface.
The map was made from images obtained by both the Cassini and Voyager spacecrafts.




This was also taken on July 14, 2005 and received on Earth July 15, 2005.
Enceladus was approximately 545 kilometres away.


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The image was taken using the CL1 and CL2 filters.



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This image was taken on March 09, 2005 by the Cassini spacecraft, and received on Earth March 09, 2005.
The camera was pointing toward Enceladus at approximately 4,177 kilometres away, and the image was taken using the CL1 and IR3 filters.


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This infrared colour image of Enceladus was obtained by the Cassini visual infrared mapping spectrometer on March 9, 2005, when the Cassini spacecraft was 9,145 kilometres away from Enceladus.

Enceladus shows substantial differences in composition or, more likely, particle size on its surface. Redder areas correspond to larger grain sizes, and appear to be correlated with craters and ridged regions. The surface of Enceladus is nearly pure water ice; no other components have been identified yet.



The middle of the image is located at the equator near a longitude of 210 degrees. The image is about 100 kilometres square.
The image shows the ratio of reflected light at 1.34 and 1.52 microns, wavelengths that are not visible to the human eye.

Cassini is scheduled for an Enceladus Flyby on July 14 2005


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