Order of Kilopi
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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Several Hyperion images here.
(Merged in Hyperion-specific thread. Sorry for any confusion.)
Everything I need to know I learned through Googling.
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Originally Posted by Kullat Nunu
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.
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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
Order of Kilopi
Hyperion's Unusual Craters
Flight to Hyperion (Animation)The mosaic is composed of five clear filter images taken during Cassini's close flyby of Hyperion on Sept. 26, 2005. The spacecraft passed approximately 500 kilometers (310 miles) above the moon's surface. Hyperion is 266 kilometers (165 miles) in diameter.
Scientists are extremely curious to learn what the dark material is that fills many craters on this oddball moon. Features within the dark terrain, including a 200-meter-wide (650-foot) impact crater surrounded by rays to the right of center and numerous bright-rimmed craters, indicate that the dark material may be only tens of meters (hundreds of feet) thick with brighter material beneath.
This movie sequence shows highlights of Cassini's Sept. 26, 2005, flyby of the odd, icy moon Hyperion, which is 266 kilometers (165 miles) across.
The sequence begins with Cassini at a distance of 244,000 kilometers (152,000 miles) from Hyperion, with the irregularly-shaped moon not yet filling the frame. From this distance, Cassini can see that strange, dark-floored craters dot this little world.
As Cassini continues toward Hyperion, it becomes apparent that the steep sides of the giant impact feature at the center have a "fluted" appearance. The walls of this feature appear to have experienced landslides that have partly covered the craters lining it.
With Cassini at an altitude of 18,000 kilometers (11,000 miles) above Hyperion, the movie then zooms in on the large crater called Meri, which itself contains several smaller craters. The rim of Meri possesses icy outcrops, while its floor is filled with landslide debris and some of the strange, dark material. The image scale at this point is about 215 meters (700 feet) per pixel.
Order of Kilopi
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.Scientists are extremely curious to learn what the dark material is that fills many craters on this oddball moon. Features within the dark terrain, including a 200-meter-wide (650-foot) impact crater surrounded by rays to the right of center and numerous bright-rimmed craters, indicate that the dark material may be only tens of meters (hundreds of feet) thick with brighter material beneath.
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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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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what a great looking Moon
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Holy battered rock, Batman. Looks like Hyperion got blasted by another rock and then the crater got peppered some more. Fantastic picture!
Last edited by jt-3d; 2005-Oct-03 at 11:22 AM.
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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?
Order of Kilopi
Perhaps.
They might have been perforations in the 'snow' that existed before a large object evacuated the huge hole. Fascinating.
Order of Kilopi
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.Hyperion has a notably reddish tint when viewed in natural color. The red color was toned down in this false-color view, and the other hues were enhanced, in order to make more subtle color variations across Hyperion’s surface more apparent.
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Cassini Image of the Day: Drawing the Drapes
Inner F-ring shepherd moon Prometheus is silhouetted against the F-ring.
Last edited by Kullat Nunu; 2005-Oct-05 at 06:12 PM.
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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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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.
Order of Kilopi
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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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
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wonderful stuff !
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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.
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Red like Mars according to this article, with the same process responsible.
Cheers.
Order of Kilopi
I have an extremely difficult time with the hypothesis that the surface of Hyperion was shaped by an arc welder. Unless the false color is really inappropriate, the outer layers do appear to be sculpted ice. Electric arcs big enough to dent the surface of a moon would certainly emit enough candle power to completely vaporize surface ice.
On the other hand, so should a large, cratering impact.
On the other hand, I have never seen one of those inverted-font ATM sights predict any of the unexpected features we have seen on any of Saturns moons.
I can't find an explanation for Hyperion of any kind...unless Cassini is really deep in the ocean and has stumbled across a sponge.
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The "arc welding" process is stil active on several locations in the solar system, it can be viewed in action on comets and on Io (the famous "volcanoes"). So if you want to compare the surface topology of Io, comets and Hyperion (or any of the moons) you should be able to see the similarities. The really important thing is that because of scalability it is possible to recreate these processes in the laboratory. There are already many examples of EDM (electrodynamic machining) showing near exact all the features of comets, moons and planets. It won't be easy to convince anyone that this is possible, but close-up views are the best way forward, and that's exactly what Cassini has been providing.
Cheers.
Order of Kilopi
Here:
http://planetary.org/blog/images/200...RN_UV3_CLR.jpg
Is an excellent (true color?) image of Hyperion. (caution: 900k), assembled by Mattias Malmer. No arc welder here: At very high levels of detail, this moon looks just like it should, if it has a solid 'dirt' core covered with a very deep layer of 'powdery' ice. It has been pockmarked with craters, and you can see the same types of talus slopes you see in fine Utah powder, while near the deep crater bottoms that have not backfilled, there is quite clear evidence the 'snow' has been 'melted' by the impact. (If you do not have a large, high resolution screen, you may not be able to see this level of detail.)
The craters are at least chaotically oriented, and bare an uncanning simularity to the blast patterns we have seen when mortars are used to trigger avalances on the pass to Jackson Hole.
This looks nothing like the surface of Io, which looks like a metallic version of the mudpots of Yellowstone.
What this moon is telling me, is that Cassini can descriminate ice or snow covered surfaces. revealing the patterns we are familier with on Earth. I would be extremely surprised if the thermal inertia on Hyperion is not highly consistent with powdery and granular snow.
Which brings up the question: If Titan also has an Icy surface, why is the Ice so brown? Why is the thermal inertia all wrong? Why would the ice form as pebbles on an icy surface?
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Ooohh. Aaaahhh. From about 0105 UT yesterday (Oct. 11), partial occultation of Rhea by Dione. Dione also transited Saturn before closest encounter starting around 1635 UT - I'm watching for that spectacle in the raw images, as Dione grows in angular diameter so fast that by the end of the transit at 1750 or so it looks as large as Saturn itself. Oh, yeah, and also to see what the streaks on Dione itself turn into at high resolution..
Order of Kilopi
I doubt it's a true color image.
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True. Hyperion is more golden in color.
Order of Kilopi
Now animated, at Emily Lakdawalla's Planetary Society Weblog
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Cassini's Dione flyby images are now online. There are several high resolution images of Dione and its Trojan satellite Telesto. There are also some coolest images Cassini has taken so far, for example this view of Saturn behind Dione in a wide-angle camera image. In this view Dione looks translucent! Telesto looks eeriely smooth in this view. Its surface is clearly filled with dust. Close-up of the "whispy terrain" faults. What's this? Globe of Dione against Saturn. Prominent fault lines near the terminator of Dione. Here's a distant view of Dione. But what is the another moon?
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Some superb color versions from the unmannedspaceflight.com forum: Dione's limb, Saturn behind Dione's limb, Dione and Saturn.
Order of Kilopi
Wow, that last shot is breathtaking.
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