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Dawn's first orbit, including RC3, March 6, 2015- June 15, 2015
ZLD
post May 12 2015, 05:27 PM
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Made a flyover for 'Spot 5' as well.

(click to animate: 4mb)


Not able to tell but looking at the smaller white areas in this perspective, makes them appear as if they have some sort of volume to them as if they were a plume, especially the upper left one. Did they rule this out yet?

Edit: Looking at this more (I feel mesmerized) the crater floor has been resurfaced at some point as well. There also appears to be some rays around the largest spot, which I thought was maybe ejecta at first, but they appear to come as go with the light. Strange. Whatever these objects are, you can definitely see the suns glint travel across them as the camera follows.

Edit 2 (5-13): For anyone wanting/needing a more focused look at the spot, I cropped and resampled this image.


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pitcapuozzo
post May 12 2015, 05:30 PM
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Do we have any albedo information at this point on the bright spots? I read it was something like 0.12, but that was a long time ago.
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Gerald
post May 12 2015, 05:44 PM
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The bright spots should be much closer to albedo 1.
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Ken2
post May 12 2015, 06:06 PM
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I'll admit the new images are perplexing of spot 5. however based on the other white spots I'm still firmly in the impact exposing ice/salty ice hypothesis camp.

In any event I made another movie of the first 6 images as the spot comes into view. I still think we are seeing the side of a crater getting illuminated and the crater reflecting more and more and appearing bigger and bigger.

As for all the new little white spots - who knows - but Ceres is clearly a body dominated by cratering, and this crater is crater upon crater upon crater - so with that in mind - I think I can trace a few old rims and the little white spots might be the edges of some of them. I have a very rough guess at where some of them might be (can't wait for higher res picts!) in the image - the crater lines are probably off - but it show the gist. Now as for why the edges of the craters are white? Maybe the main impact caused shrapnel scraping the tops off or dusting the tops with ice.

Click to animate GIF

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Gerald
post May 12 2015, 06:52 PM
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Another mechanism, I could imagine, are landslides (triggered e.g. by physical weathering / thermic cycling) at steep slopes exposing fresh (not yet darkened) material.
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ngunn
post May 12 2015, 09:03 PM
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QUOTE (Ken2 @ May 12 2015, 07:06 PM) *
I'm still firmly in the impact exposing ice/salty ice hypothesis camp.


I find myself in that camp too, although there are well placed scientists invoking volcanic processes so I don't know. . . It's easy to imagine an impact triggering landslips nearby so maybe that's what we're seeing in some places at least.
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jgoldader
post May 12 2015, 09:41 PM
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Looking at the animation for spot 5, I'm tempted to see the spot at the crater's center as being a depression. On both the right and left sides of the white spot, in the image, there appears to be a ridge or crater rim a couple of pixels high.

I would think it was a fresh crater that had penetrated into a watery/icy region, then filled up with fresh ice, but why is that tiny spot so conspicuous on the entire asteroid? Why just the one place? The rest of Ceres is so battered, it would make more sense to me if there were many things like spot 5. I know there are some bright areas, but 5 really jumps out.
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Gladstoner
post May 12 2015, 10:10 PM
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QUOTE (jgoldader @ May 12 2015, 03:41 PM) *
but why is that tiny spot so conspicuous on the entire asteroid? Why just the one place? The rest of Ceres is so battered, it would make more sense to me if there were many things like spot 5. I know there are some bright areas, but 5 really jumps out.


To me, that is what is most intriguing about it. If it is merely bright stuff beneath the regolith, I'd expect something more like Callisto.
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Gladstoner
post May 12 2015, 10:28 PM
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Just trying to map out the bright areas:

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Gladstoner
post May 13 2015, 06:51 AM
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Crater floor fractures?

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antipode
post May 13 2015, 10:31 AM
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Is that rift in any way radial to the mountain/'volcano' thingy? Could they be associated?



Why am I thinking Tharsis?

P
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0101Morpheus
post May 13 2015, 10:39 AM
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Too soon to tell unfortunately. Impacts can create rifts too, and Ceres has had an awful lot of them.
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Phil Stooke
post May 13 2015, 12:30 PM
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I don't know if I can think of a single example of an impact producing a rift. The grooves of Phobos are often cited as such, but that's a hypothesis, not a certainty, and other possibilities have been suggested (impact of Mars ejecta, jointing during excavation from a larger primary, or drainage between blocks in a rubble pile, for instance). The "Imbrium Sculpture" pattern of radial lineations on the Moon is now regarded as due to ejecta scouring and deposition, not structural in origin as suggested decades ago.

It's much more likely that this feature is a chain of secondary craters. Think Rima Schroedinger or the Rheita Valley on the Moon.

Phil


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... because the Solar System ain't gonna map itself.
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John Broughton
post May 13 2015, 12:47 PM
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Has anyone noticed in the RC3 movie, small hills (cones) at the bright spot near the large mountain, and that they and the mountain are both on a fault line, and that this system of faults extends through the crater with the brightest spots of all?

John

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tasp
post May 13 2015, 01:01 PM
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The crater Turgis and the 'tiger scratches' on Iapetus came to mind as something to compare the rift on Ceres to. The association of the crater and the 'scratches' on Iapetus might be coincidental, and AFAIK, there seems to be only one rift seen on Ceres and IIRC, there are 3 'scratches' noted on Iapetus.
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