CICLOPS: Cassini Imaging Central Laboratory for OPerationS

Enceladus and Dione Rev 165 Raw Preview

NASA's Cassini spacecraft captured these raw, unprocessed images of Saturn's moons Enceladus and Dione during close flybys on May 2, 2012. The flybys were the last close encounters of these icy moons that Cassini will make for three years.

Cassini flew by Enceladus at an altitude of about 46 miles (74 kilometers). This flyby was designed primarily for the radio science sub-system to measure variations in Enceladus' gravity field.

On approach to Enceladus, Cassini's cameras imaged the icy satellite's south polar plume, which consists of jets of water ice, water vapor and organic compounds sprayed into space from the moon's famed "tiger stripe" fractures. The plume images were captured at distances ranging from 259,000 miles (416,000 kilometers) down to 66,000 miles (106,000 kilometers) when the satellite was just a thin crescent and the plume was backlit. During closest approach, the radio science team looked for a concentration of mass at the south pole that could indicate sub-surface liquid water or an intrusion of warmer-than-average ice that might explain the intriguing geologic activity at the south pole. After the closest approach, the composite infrared spectrometer obtained a map of Enceladus' sun-lit side while Cassini's visible light cameras rode along and captured several images of the moon's leading hemisphere at resolutions of about 1,500 feet (450 meters) per pixel.

Shortly after passing Enceladus, Cassini had a non-targeted encounter of Dione. At closest-approach, the spacecraft flew within about 5,000 miles (8,000 kilometers) of the moon. Cassini's cameras captured several mosaics during this encounter, including one taken around the time of closest approach that covered a fracture named Latium Chasma at resolutions of about 175 feet (53 meters) per pixel. Other mosaics cover much of Dione's northern hemisphere that faces away from Saturn in its orbit, focusing particularly on the moon's ridges, an ancient impact basin and the wispy streaks that Cassini scientists now know are tectonic fractures.

Later this month, a close encounter with Titan on May 22 will pitch the spacecraft up out of the equatorial plane and into a nearly three-year-long phase of inclined orbits that will showcase the northern and southern reaches of Saturn. On March 9, 2013, Cassini will make a close pass by Rhea, but the spacecraft won't have another close, targeted encounter with any of Saturn's other icy satellites until June 2015, when it encounters Dione. Cassini will make its next flyby of Enceladus on Oct. 14, 2015.

May 2, 2012: Enceladus 'Rev 165' Raw Preview #1 - This raw, unprocessed image of Enceladus was taken on May 2, 2012 and received on Earth May 2, 2012.
May 2, 2012: Enceladus 'Rev 165' Raw Preview #2 - This raw, unprocessed image of Enceladus was taken on May 1, 2012 and received on Earth May 2, 2012.

May 3, 2012: Enceladus 'Rev 165' Raw Preview #3 - This raw, unprocessed image of Enceladus was taken on May 2, 2012 and received on Earth May 2, 2012.
May 3, 2012: Enceladus 'Rev 165' Raw Preview #4 - This raw, unprocessed image of Enceladus was taken on May 2, 2012 and received on Earth May 3, 2012.
May 3, 2012: Dione 'Rev 165' Raw Preview #1 - This raw, unprocessed image of Dione was taken on May 2, 2012 and received on Earth May 3, 2012.
May 3, 2012: Dione 'Rev 165' Raw Preview #2 - This raw, unprocessed image of Dione was taken on May 2, 2012 and received on Earth May 3, 2012.
May 3, 2012: Dione 'Rev 165' Raw Preview #3 - This raw, unprocessed image of Dione was taken on May 2, 2012 and received on Earth May 3, 2012.
May 3, 2012: Dione 'Rev 165' Raw Preview #4 - This raw, unprocessed image of Dione was taken on May 2, 2012 and received on Earth May 3, 2012.
May 3, 2012: Dione 'Rev 165' Raw Preview #5 - This raw, unprocessed image of Dione was taken on May 2, 2012 and received on Earth May 3, 2012.
May 3, 2012: Dione 'Rev 165' Raw Preview #6 - This raw, unprocessed image of Dione was taken on May 2, 2012 and received on Earth May 3, 2012.
May 3, 2012: Dione 'Rev 165' Raw Preview #7 - This raw, unprocessed image of Dione was taken on May 2, 2012 and received on Earth May 3, 2012.
May 3, 2012: Dione 'Rev 165' Raw Preview #8 - This raw, unprocessed image of Dione was taken on May 2, 2012 and received on Earth May 3, 2012.
Alliance Member Comments
Judit (May 7, 2012 at 1:08 PM):
Aw, no more Enceladus for a while :-( Can't wait for the May 22 Titan flyby though! Thanks for sharing these images. They are beautiful and breathtakingly detailed. To think how close the spacecraft was to these bodies, and to think how far it is from us... Mind-boggling!
NeKto (May 7, 2012 at 8:41 AM):
i also find that scale makes a difference. i only have this problem with high resolution images. the greater the actual area the image covers, the less likely i am to see the craters "inverted."
CarlinForsyth (May 5, 2012 at 6:18 PM):
You are correct in wanting to turn the images upside down. Your brain has learned to "know" that light comes from above. When that perspective changes as in these images you "see" incorrectly. I have seen this even in a Newtonian telescope when viewing the Moon. A book titled "Visual Intelligence" helps to explain this and other ways that your vision is a construct. Its a very interesting book. Hope this helps. And yes with a little practice you can "flip" them in your mind. I think some details become easier to study when inverted, if you will.
NeKto (May 4, 2012 at 8:37 AM):
I have the same problem with most of the high res images of the icy surfaces. i thought it was just me. (glad to know i'm not alone!)
even tho i know i am seeing craters, my brain still interprets the images as mounds. every once in a great while, i can change my perseption and see the craters. wish i knew how to do it all the time.
lsludwig1 (May 3, 2012 at 3:15 PM):
Is it just me or is it difficult to overcome the optical illusion in the closeup Dione photos that the craters look instead like mounds. I've turned my head sideways this way or that and I am unable to view these photos correctly. Perhaps if I download them and turn them completely upside down. Or maybe they really are undiscovered mounds - Ha!

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