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Dawn's first orbit, including RC3, March 6, 2015- June 15, 2015
Gladstoner
post May 22 2015, 08:16 AM
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QUOTE (John Broughton @ May 22 2015, 12:56 AM) *
"There appears to be a dark linear feature extending between the bright areas"

It's part of the regional system of parallel grooves. This particular one extends well outside the crater rim on both sides and joins up with the most prominent groove about two crater diameters to the ESE. Some minor spots in the crater are not aligned, so I expect we'll see more cracks show up there as the resolution improves.


Hmmm.... If these turn out to be fractures that run deep, they could potentially serve as conduits for ascending fluids.
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John Broughton
post May 22 2015, 08:53 AM
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QUOTE (Gladstoner @ May 22 2015, 08:16 AM) *
Hmmm.... If these turn out to be fractures that run deep, they could potentially serve as conduits for ascending fluids.

Here's the general course of that fault.
Attached Image

Like the large mountain spot and another spot of small cones near that, the bright spots coincide exactly with fractures in the crust. The great length of some of these faults is a definite sign they run deep.
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TheAnt
post May 22 2015, 11:27 AM
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The idea of ascending fluids is a good one, but still have to rise a very long distance against gravity.
If it on the other hand is water vapour, created by water boiling against the close-to-vacuum in a deep crack.
Then vapour pressure would give it an extra boost enough to reach the surface.
This could deposit salts and ice, either or both at the exit, so it does not solve the problem of what the bright material is composed of.
But do at least make transportation to the surface more likely.
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Habukaz
post May 22 2015, 05:06 PM
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The latest released OpNav 8 image appears to have a much better quality, although it does not show the brightest spots (grr).

If we got more of the feature below (it should be a crater) over the weekend, that would be interesting. It might hold some important clues to all bright spots, including the brightest.

Attached Image


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scalbers
post May 22 2015, 05:40 PM
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Here's a revised Ceres map, using 4 more recent images on top of the previous official map. Resolution now up to 4K.

Attached Image


I'll see about adding the OpNav posted just above.


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Ken2
post May 22 2015, 06:56 PM
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The two Spot5 Opnav8 images to date - with all the unfortunate jpeg compression artifacts.

The top half of the image has the more recent (5/21/2015) halfway to the limb image stretched and rotated to compare exactly with the first one (5/20/2015). As you can see it shows a bunch more small craters to the left of the big spot. A complex crater morphology such as this can produce any number of weird patterns. If it's an impact - I think it is going to take HAMO or LAMO picts to determine if it was one parent body and shrapnel/secondaries or a close rubble pile breakup. Given the direction of the dark right sided rays, I still vote for a single impact with a few direct secondaries.

Attached Image
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scalbers
post May 22 2015, 06:58 PM
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And here is the map with today's OpNav added.

Attached Image




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Ken2
post May 22 2015, 08:46 PM
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QUOTE (scalbers @ May 22 2015, 11:58 AM) *
And here is the map with today's OpNav added.


Thanks - I like the maps scalbers - keep 'em coming!

I have one item on my wish list - would it be possible add a second map with north and south polar projections? - the poles get so distorted in Mercator projections.
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antipode
post May 22 2015, 10:07 PM
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Hmm, hard to tell with that projection, but is the small white patch upper right (not sure if its one of the officially numbered patches) 'downrange' from the twin splotches?



I know, probably trying to find patterns where none exist! I like the fracture[s] idea actually, that would be more interesting than just a low angle impact.

P
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Gladstoner
post May 22 2015, 10:40 PM
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A can of Diet Coke today had me thinking. We all have accidentally left a can of soda in the freezer. Long after a half hour (when it should be cold enough to drink, i.e. should have been taken out of the freezer), carbon dioxide begins to come out of solution as the water freezes. Eventually the can ruptures as the gas pressure becomes too great, and a very-syrup-rich slurry sprays into the freezer interior to make a fine mess.

Now back to Ceres. Assuming the body differentiated into a rocky core and icy mantle, could a similar process have happened within Ceres? Ice would first form near the surface and progressively freeze downward. Various volatiles (like the CO2 in the can) and cations & anions/dissolved salts (the syrup) would become more and more concentrated in the remaining brine. Over the age of the solar system, the water probably would have frozen out long ago, but there could still be remaining pockets of gas and possibly highly-concentrated brine. These would be *roughly* analogous to petroleum reservoirs on Earth in the way they permeate the substrates. Now, Ceres wouldn't rupture like a pop can, but some of the volatiles may eventually make their way to the surface (thanks to some minor tectonic adjustments due to an impact, perhaps?). The conduit at or near the surface would be marked with bright salt deposits. The extra brightness of the material could be due in part to micrometeoritic impacts on exposed transparent or translucent salts, kind of like the frosting that occurs when a similar material is sandblasted.

Of course this could be completely wrong, but it seems to make the most sense to me.
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scalbers
post May 22 2015, 11:08 PM
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Good idea Ken2 - I put together a quick procedure to make a polar image. Shapes are a bit distorted near the edge as I've yet to add the niceties of a stereographic projection - this should give an idea of things though. North pole is in the center and zero longitude should be on the top. The south pole is devoid of data on this map so I'm holding off on it for now.

Attached Image


That small white spot on the right pointed out by antipode (2 posts up) indeed looks interesting. It might be close to being on a great circle from the two brightest spots from what I can tell. Looking at the cylindrical map (5 posts up) in Celestia might help, though it should be pointed out the cylindrical map is in planetocentric coordinates and Celestia usually expects planetographic. I'm accounting for Ceres being an oblate spheroid in this manner.
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John Broughton
post May 22 2015, 11:56 PM
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There are at least three possible volcanic cones associated with this spot. I've inverted the image so it is illuminated from above.
Attached Image

The spot lies on a fault line running from the top left to the bottom right corner, but is indistinct at this high sun angle. As far as I can tell, hills are at the centre of all spots, whether they lie within craters or not.
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PDP8E
post May 23 2015, 03:12 AM
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My deconvolve program had a little fun with this JPGy file... but not the best of results (arrggg!)
I turned down the background to try to focus on the lighter stuff... its about 5x
Attached Image

Its obviously an abandoned asteroid mining operation ... nothing to see here .... move along people... smile.gif
We shall have to wait for more RCx to HAMO to LAMO to WHAMO!






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CLA CLL
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Gladstoner
post May 23 2015, 05:22 AM
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QUOTE (PDP8E @ May 22 2015, 10:12 PM) *
Its obviously an abandoned asteroid mining operation ...


Anyone can see it's an Illudium Q-36 Explosive Space Modulator.
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SFJCody
post May 23 2015, 06:34 AM
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I just think the whole of Ceres is like Vastitas Borealis on Mars. Regolith over a widespread layer of almost pure water ice. As with Mars, the most recent impacts reveal this ice. Over longer timescales the exposed ice sublimes away and eventually escapes Ceres.
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