In her Planetary Society Blog, Emily Points out the craters are all small, none of even a medium size.

That seems to indicates a one-shot, fairly recent cratering event. I can't help but wonder if this is not what a small, Ice-shrouded moon would look like after passing through one of the rings.

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jwj

It's ok not to know. We should try harder to find out.

Several Hyperion images here.

(Merged in Hyperion-specific thread. Sorry for any confusion.)

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Great stuff,

The craters filled with dark material resemble Martian features, and cometary features. I wonder what the explanation will be, surely not impact craters?

Cheers.

very good info



more pics here

Tethys and Saturn's Rings
http://www.saturntoday.com/news/viewsr.html?pid=18188
shoreline seen on Titan
http://www.esa.int/SPECIALS/Cassini-...GZ7X9DE_0.html
Saturn rings
http://www.spacedaily.com/images/cas...-desk-1024.jpg
Close Look at Tethys
http://saturn.jpl.nasa.gov/multimedi...m?imageID=1750

Hyperion's Unusual Craters



Flight to Hyperion (Animation)

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I don't understand the observational motivation for this statement. The dark material appears to be centered in the bottoms of the deepest craters, and is not apparent in the fluted white draws and edges. The most straight forward interpretation would appear to me to be that a white material is resting on a darker substrate.

It is certainly possible that a darker material "burned" its way through a lighter material - you often see this on the side of a road in winter, when a sanding truck has flung dark sand upon the snow. The darker sand absorbs more radiant energy and melts through surrounding snow. But in this image, there is no apparent dark material in the shallower craters. This would seem to me to indicate that the dark material is exposed at the bottom, rather than a primary actor, in this surface weathering process.

Edited to add:

Ok, I had to blow the image up a little more. Yes, in one or two of the craters, there does appear to be dark material overlaying white: But in these craters, the dark material has a 'fanned' rather than a circular distribution, and if anything, this is the exception that proves the rule: most of the dark material is in circular patterns at the bases of the deepest craters.

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jwj

It's ok not to know. We should try harder to find out.

That is really one strange looking moon. It looks like what I expected a comet nucleus to look like, if we could see one in the outer solar system. Some of the craters look like upraised vents left over from jet activity. Has anyone said anything about what looks to me like a crater rim almost as wide as Hyperion itself?

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http://www.rrac.org

what a great looking Moon

Holy battered rock, Batman. Looks like Hyperion got blasted by another rock and then the crater got peppered some more. Fantastic picture!

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Yet many of the craters inside the big one appear to be elongated in the direction away from the center of the main crater; and what's up with those petal shaped craters along the rim wall? For a non-mosaic image, the shadows on the crater walls sure are strange. It looks as if the moon is illuminated by light from at least two different directions. Mightn't the features of the smaller craters be better explained if they resulted from outgassing?

Perhaps.

They might have been perforations in the 'snow' that existed before a large object evacuated the huge hole. Fascinating.

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jwj

It's ok not to know. We should try harder to find out.

http://ciclops.org/view.php?id=1507

Red? Are we looking at Iron on Hyperion - Is it red like Mars, Kolob Canyon, or Phoebe? Red algae? I don't understand why Ciclops has not released an image in natural color. When Cassini first approached Saturn, images of all types, including spectroscopic checkerboards, were routinely featured in Ciclops presentations.

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jwj

It's ok not to know. We should try harder to find out.

Cassini Image of the Day: Drawing the Drapes



Inner F-ring shepherd moon Prometheus is silhouetted against the F-ring.

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Cassini Image of the Day: Brilliant F-Ring



Similar to the yesterday's image, but this time with Pandora.

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Science is a way of trying not to fool yourself. The first principle is that you must not fool yourself, and you are the easiest person to fool.
-- Richard Feynman

Say, has anyone figured out what the Iapetus equatorial ridge is?

That seems so absolutely amazingly puzzling. How could it exist? Why would it exist?

I know it's silly, but that ridge just seems so improbable! It almost seems acceptable that it was built, a long long time ago. Simply because I can't think of another way it could have been created.

It puzzles me.

---Vil.

http://www.saturntoday.com/news/viewsr.html?pid=18243

This is a great false color image of Tethys. True color would be nice, since my brain does not have a built-in predator co-processor.

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jwj

It's ok not to know. We should try harder to find out.

All,
Those 'straight-line' objects on Dione and Rhea. Ages ago, I posted about them on the Asterisk to get others' views and didn't. Just today, craterchain has suggested that such objects are the result of the impact of tidally fragmented objects. Googling for "crater chains" gets several clear examples, on the Moon, Callisto and even possibly the Earth, though some refer to "extraterrestrial strafing runs". I suppose that explanation IS about right, if you take out the "intelligence"!

Still, it worries me that the features that originally caught our attention, Travis' Fissure etc., are remarkabaly smooth sided for crater chains, or is that the result of 'image manipulation'?

John

wonderful stuff !

If you look at those straight features on Dione, Rhea and other moons, they are not really straight, but follow the curve and topology of the surface (I'm not talking about fissures, or "cracks", those can be formed differently). "Crater chains" is a correct description; upon closer examination the straight grooves are made up of overlapping craters. This means that different kinds of crater chains only differ in the space between the craters, and the width of the craters.

All of them are thought to be caused by fragmented impactors, which is clearly a major problem, because how can a fragmented object impact in a straight line, following the curve of a moon's surface and still be so closely spaced as to form overlapping craters. This raises the interesting question if we know how crater are formed at all. On large bodies like Mars, there is an alternative explanation: collapse pits. That explanation assumes that below the surface some erosional process causes empty spaces that subsequently collapse. The problem with that explanation is that it doesn't work for small moons and another problem is that the collapsed "roof" would leave a lot of debris inside the pits, which is clearly absent.

Cheers.