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Dawn approaches Ceres, From opnav images to first orbit
Ron Hobbs
post Feb 10 2015, 03:48 AM
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DAWN is now less that 100,000 km from Ceres.
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Toma B
post Feb 10 2015, 11:16 AM
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There is this gif animation on Max Planck Institute site. It seems to me that there are some more details in it than what's been shown in first release. There are definitely more details in craters at the bottom of the image. Central peaks can be seen in at least 3 craters, and there is clearly visible unsymmetrical black layer around that great white spot (best viewed in frame 19).

Attached Image
# Frame 19 #

So I extracted frames from it and made one of my back and forth animations.
Some more details visible on Ceres surface

Here are separated frames of this animation if anybody else would like to try some sharpen/brightness/contrast/unsharp mask or whatever.
Individual frames of this animation

Sorry for my English...


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TheAnt
post Feb 10 2015, 12:20 PM
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Thank you Toma for your work on those images.

That bright feature keep looking smaller and brighter and appear saturated in brightness, so I call all bets off for the size and brightness of that one until Dawn get close enough for get get better resolution images.
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elakdawalla
post Feb 10 2015, 04:10 PM
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That animation is nicer quality than the previously released ones -- it has a wide range of gray levels. Like the still image that DLR released previously, it's been enlarged by a factor of 10 from the original data and then sharpened.

I tried a slightly different stretch on it; I also reduced its size by half, so it's still 5 times the original resolution (click to enlarge):



I'm intrigued by the shape of the limb at the top -- it's clearly asymmetrical during parts of the rotation. There is some topography up there.


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Sherbert
post Feb 10 2015, 07:16 PM
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Thanks to everyone for their wonderful images. Even with this range of trickery it is still difficult to be certain about specific areas. One thing is certain is that it is a rough and rugged terrain with valleys, craters, mountains and hills all merging.

Looking at Toma's lovely GIF, as the "White Spot" disappears over the horizon there is a hint that it is projecting above the surface. My guess would be a mountain of ice rich material thrown up by an impact. The impact might have been at a low angle to the surface coming in from the Northeast, hence the central mountain is moved Southwestward. The unusually dark terrain would appear to be the shadow of this mountain, but could be different, deeper subsurface material, below the ice mantle, exposed by the "scraping" impact.

I have now decided that it looks most like a Walnut. laugh.gif
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Habukaz
post Feb 10 2015, 07:52 PM
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Not much of an update, but the Dawn Twitter account suggests that the 12 February images will be released next week, as one could expect. Here's hoping for a Monday release at the latest.

With Ceres having a rotation period of about 9 hours, the fact that a full rotation is photographed should not in itself delay the images much (except from potentially longer data downloading times due to a greater amount of data obtained).

QUOTE (Toma B @ Feb 10 2015, 12:16 PM) *
There is this gif animation on Max Planck Institute site. It seems to me that there are some more details in it than what's been shown in first release. There are definitely more details in craters at the bottom of the image. Central peaks can be seen in at least 3 craters, and there is clearly visible unsymmetrical black layer around that great white spot (best viewed in frame 19).


It really looks like there's a chasm at the lower right limb around the end of that animation.

If there is at least one upcoming image with a similar viewing geometry, then we should be able to see it more or less clearly that it actually is a chasm, if it exists.

There are hints at other (potential) smaller valley-like structures in the same area as well.


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antipode
post Feb 10 2015, 09:41 PM
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The 'owl eyes' basins just south of the equator seem to both be double ring basins to my eyes. Yet while large they don't seem to be THAT large (~200km on the outside ring?). I know the size of basins where the double ring appears depends on the size and composition of the parent body, and also presumably on the composition and velocity of the impactor. Does anyone know what the numbers for Ceres are?

P
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ngunn
post Feb 10 2015, 09:51 PM
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QUOTE (Sherbert @ Feb 10 2015, 07:16 PM) *
as the "White Spot" disappears over the horizon there is a hint that it is projecting above the surface.


I'm really not seeing that. To me it looks like it is located inside a big crater which also contains the adjacent dark area. When it's near the limb the long axis of the bright spot seems to be smaller as if part of the feature is obscured by topography, consistent with it being in a hollow.
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Julius
post Feb 10 2015, 10:57 PM
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I do understand the excitement of trying to Iinterpret features visible on Ceres but would rather wait and see knowing that we will be getting much improved images in the near future so various attempts at interpretation at this point in time seem to me to be premature.
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Gladstoner
post Feb 10 2015, 11:06 PM
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QUOTE (Julius @ Feb 10 2015, 04:57 PM) *
.... we will be getting much improved images in the near future so various attempts at interpretation at this point in time seem to me to be premature.


Of course it is, but sitting on one's hands until then is no fun. smile.gif
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Gerald
post Feb 11 2015, 02:14 PM
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QUOTE (antipode @ Feb 10 2015, 10:41 PM) *
The 'owl eyes' basins just south of the equator seem to both be double ring basins to my eyes...

My still a little vague perception has been, that this doubling continues to the west along the presumed valley, and is hinted at at some other locations, too.
One guess for the cause could be exposure of the presumed layering of Ceres' crust.
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TheAnt
post Feb 11 2015, 03:45 PM
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QUOTE (antipode @ Feb 10 2015, 10:41 PM) *
The 'owl eyes' basins just south of the equator seem to both be double ring basins to my eyes.


They certainly do look very much like double rings basins, the question is if they have been created by the same violent mechanism as found elsewhere. Lets say as on the Moon or Mercury, and the most likely scenario. Yet on Ceres one could imagine that they were not made instantaneous but that the first impact expose ice which sublimate and erode outward for some distance creating the double feature. Perhaps less likely, yet with the distance from the sun/temperature range the latter could be considered.
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algorimancer
post Feb 11 2015, 06:29 PM
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I've been thinking of these basins as resembling butterfly wings or Rorschach blots... my sense from reviewing the stereo pairs is that the west basin is composed of a larger crater overlaid by a smaller crater on one side. I find the albedo variations interesting. In the stereo pairs, the apparent whitish spot at the center of the left basin seems to correspond to light reflecting off a topographic slope, rather than a genuine exposure of bright material (it could be both, I suppose). I'm leaning towards seeing the lower-albedo (darker) regions within the basins as being actual lower albedo areas rather than lighting effects from the topography; whether the lower albedo is a result of rougher topography or different chemistry remains to be seen. Color images would be really helpful here smile.gif
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Sherbert
post Feb 11 2015, 08:32 PM
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QUOTE (ngunn @ Feb 10 2015, 09:51 PM) *
I'm really not seeing that. To me it looks like it is located inside a big crater which also contains the adjacent dark area. When it's near the limb the long axis of the bright spot seems to be smaller as if part of the feature is obscured by topography, consistent with it being in a hollow.


This is what I was inferring. The brighter material is the central mountain that forms in an impact crater. If the angle of impact is not perpendicular to the surface, say at 45 degrees, that central peak is shifted and distorted along the direction of flight of the impactor. The impact appears to have ploughed a broad furrow, the dark terrain, pushing the bright material up into a mountain ahead of it. The bright material on the original, admittedly low quality image, seems to be continuing over the southwest rim of the crater. I agree, the mountain's base does appear to be hidden as it disappears over the horizon, hence my speculation it is the "central" mountain in an impact crater.

At this point I would have to echo Gladstoner's sentiments, the speculation is likely to be wrong, but at this time, it's like the fun of trying to guess what is in a present before you open it.
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0101Morpheus
post Feb 12 2015, 07:16 PM
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If we weren't allowed to speculate than this forum would be quite a bit smaller!

Today makes the beginning of an exciting week for the Dawn mission. Like was explained a couple pages back, from today to the 19th, Ceres is going to triple in resolution.
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