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Dawn's first orbit, including RC3, March 6, 2015- June 15, 2015
RotoSequence
post Jun 5 2015, 06:07 PM
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Excellent stuff, Daniele!

If you've still got your experiment tray ready to go, could you try making a crater with an extremely shallow angle impact? I'd try it myself, but I think I'd get some stern looks of disapproval for wasting food and making a mess. biggrin.gif
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ngunn
post Jun 5 2015, 08:42 PM
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I love to see an experiment, and the cartoon scenarios are also a great basis for discussion. Scenarios b and c look good to me for the various white spots. I would just add that in scenario b the original big impact would likely have exposed fresh ice, subsequently re-covered with dirt before the recent smaller impact event. (You don't need to rely on the coincidence that the large impact narrowly missed going deep enough, allowing the smaller one to finish the job.)
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Gladstoner
post Jun 5 2015, 10:52 PM
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Same thing, different day (i.e. TIF flipped, JPG'd):

Attached Image


It would be interesting to know why the images end up reversed.
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scalbers
post Jun 5 2015, 11:07 PM
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Here's a map update with the latest images added:


Attached Image


Full 4K resolution and polar views are here.


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Bill Harris
post Jun 6 2015, 01:44 AM
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QUOTE (Gladstoner @ Jun 5 2015, 05:52 PM) *
It would be interesting to know why the images end up reversed.


_Very_ good question. I was starting to notice that things didn't look "quite right" and then I saw that you were noting "flipped" on your images. If I'm catching this correctly it looks like the images started to be reversed with the Southern Hemisphere campaign, PIA19554. Not a big deal, but an annoyance with annotated images.

--Bill


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Gladstoner
post Jun 6 2015, 03:42 AM
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QUOTE (Bill Harris @ Jun 5 2015, 08:44 PM) *
If I'm catching this correctly it looks like the images started to be reversed with the Southern Hemisphere campaign, PIA19554.


At least toilets on Ceres will now flush in the same direction as in the north. smile.gif
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antipode
post Jun 6 2015, 06:37 AM
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QUOTE


That is incredibly cool Daniele, reminiscent of some of Emily's montages. Can I make 2 small suggestions however?
1) The Chariklo image is the only non-photograph, its an artist's conception. Perhaps identify it as such
2) An image of Proteus, to scale, will remind viewers that the transition from 'round' to 'potato' shaped is not a totally predictable one

P
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SFJCody
post Jun 6 2015, 09:11 AM
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I'm really enjoying Ceres now. A great intermediary between the silicate worlds and the ice moons & TNOs. Onwards, closer!
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ngunn
post Jun 6 2015, 09:20 AM
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Looking back at this image I now think the big mountain may be the remains of the central peak of an almost-erased impact basin similar in size to the one at the lower left terminator here:
http://www.unmannedspaceflight.com/index.p...st&id=35981

That crater also has a central peak that takes the form of a short linear ridge with at least one white patch on its northern slope:
http://www.unmannedspaceflight.com/index.p...st&id=35989
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Gladstoner
post Jun 6 2015, 05:26 PM
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QUOTE (ngunn @ Jun 6 2015, 04:20 AM) *
Looking back at this image I now think the big mountain may be the remains of the central peak of an almost-erased impact basin similar in size to the one at the lower left terminator here:
http://www.unmannedspaceflight.com/index.p...st&id=35981
That crater also has a central peak that takes the form of a short linear ridge with at least one white patch on its northern slope:
http://www.unmannedspaceflight.com/index.p...st&id=35989

If those are central peaks, then that may indicate the white material was drawn up from below in places. The Decaturville impact structure in Missouri comes to mind:

Attached Image


Here, lower, older rocks were drawn up by the central rebound. The tan in the middle is Cambrian, and the red dot represents huge, rootless blocks of Precambrian granite. The outer ring is younger Ordovician. A cross section of the structure:

Attached Image


(Edit: ring faults not included in diagram for simplicity.)

If this happened on Ceres, the sparse nature of the white stuff could indicate an overall spotty distribution, an occurrence at varying depths, or both.
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scalbers
post Jun 6 2015, 08:29 PM
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Greetings - this map version has some revisions in the area of the two southern basins to try and show more details.

Attached Image


Full 4K resolution and polar views are here.


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ngunn
post Jun 6 2015, 09:02 PM
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QUOTE (Gladstoner @ Jun 6 2015, 06:26 PM) *
If those are central peaks, then that may indicate the white material was drawn up from below in places.

Interesting idea. I was thinking of the ice being quite near the surface everywhere, as at the Mars Phoenix site, and being exposed either by fresh impacts or landsldes on steep slopes, but maybe it's mainly deeper and particular circumstances are required to bring it to the surface.

There is an issue that the dirt overlying the ice may well be denser than the ice. An impact or anything else that disturbs the status quo could trigger some overturning.

scalbers: great map!
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Gladstoner
post Jun 8 2015, 08:42 AM
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It is tricky to discern the orientation of the valleys between the large basin and spot 5, so I took scalber's cylindrical map and brought it into Celestia:

Attached Image


Some valleys radiate from the basin, but the ones that extend to spot 5 do not. I thought all the valleys were due to the big basin, but something else seem to be in play.
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Floyd
post Jun 8 2015, 09:25 AM
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QUOTE (scalbers @ Jun 5 2015, 07:07 PM) *
Here's a map update with the latest images added:


Attached Image


Full 4K resolution and polar views are here.


North West and also ENE of white spots 5 are dark lake-shaped regions of uniform darkness (but not black). Are these just image artifacts or something real?


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scalbers
post Jun 8 2015, 04:49 PM
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I'm glad to see such helpful good eyes on this forum. The dark area to the NW (shown below) I think you're referring to would be heavily shadowed craters. I'll check to see how easy it is to substitute another image in that area. Where would be the area to the ENE of spot 5? I also still have to catch up with a map that identifies the white spots.
Attached thumbnail(s)
Attached Image
 


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