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Dawn approaches Ceres, From opnav images to first orbit
vikingmars
post Jan 27 2015, 03:25 PM
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And here is the NEW Ceres !!!
Left : taken by the Hubble Space Telescope in 2004. Right, taken by the Dawn spacecraft in 2015 (yesterday from 237,000 kilometers)...
with a quick processing I've done for you... It looks like a "bumpy" world.
Enjoy smile.gif

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algorimancer
post Jan 27 2015, 03:26 PM
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Very clear craters in the new images. What I'm finding particularly interesting is the multi-ringed appearance of the two large adjoining basins (presumably craters) at the bottom, where it progresses from a light color at the center, to a dark ring, a lighter ring, and finally an outer ring which appears to be the basin rim. The dark inner ring appears not to be a topographic feature. The left basin in particular shows a hint of a central white spot similar to the bright feature in the upper portion of the image. I seem to also be seeing hints of grooves, with a major one in the bottom-right, arcing from lower left to upper right, and I'm pretty sure the two big lower basins are crossed from left to right by an even broader groove. I get a sense that we're seeing hemispheric asymmetries in terrain, with the lower portion having rather a lot more topography than the upper portion, but this may be due to seeing more of the terminator there.

I'm presuming up is north and down is south?

Can't wait til the next pics smile.gif

Edit: Incidentally, what's up with the apparent Moire pattern in the animation?
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volcanopele
post Jan 27 2015, 03:34 PM
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Yep, north is more or less up.

PSI has another page up about the new OPNAV images:

http://www.psi.edu/news/opnav2ceres

They note that there appear to be topographic depressions associated with the two main, southern hemisphere dark regions with ribbon-like features extending from each of them. I would be a little careful about interpreting those ribbon-like features too much from this dataset. Could be canyons... could be just a random "chain" of impact craters.


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elakdawalla
post Jan 27 2015, 04:11 PM
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QUOTE (algorimancer @ Jan 27 2015, 07:26 AM) *
Edit: Incidentally, what's up with the apparent Moire pattern in the animation?

Just a result of upsizing the original images -- you're seeing pixel boundaries, and your brain really wants those to be moving lines. Also looks like the interpolation algorithm tried to make hard boundaries of those pixel boundaries edging into Ceres' disk.


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TheAnt
post Jan 27 2015, 05:38 PM
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@elakdawalla:

Yes I found this upsizing to be annoying even before reading your post. This is a perfect example when a larger processed image isn't better.

The comparison image presented by vikingmars is ok though, thank you for posting.

And yes, looks a bit bumpy, have Ceres been battered so hard that it have gotten some cracks in the surface or is that something else we see a hint of?
The superficial similarities to some moons of Uranus have gotten stronger, those could be features similar to what have been seen on Ariel and Titania, well lets wait for the next set of images, I guess this only have wetted our appetite for more and sharper ones. =)
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Phil Stooke
post Jan 27 2015, 05:49 PM
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Here's a set of processed versions of the GIF frames (each one is a composite of three frames, merged, reduced in size, sharpened and contrast-adjusted)

Phil


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DrShank
post Jan 27 2015, 05:59 PM
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QUOTE (Phil Stooke @ Jan 27 2015, 11:49 AM) *
Here's a set of processed versions of the GIF frames (each one is a composite of three frames, merged, reduced in size, sharpened and contrast-adjusted)

Phil


Attached Image



nicely done phil. i suspect some linear features are present to the south, and definitely a cuspate ridge. could be a tectonic trench ala Ithaca Chasma on Tethys, but we have been fooled at these kinds of resolutions before, so I'm not placing bets just yet.


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dvandorn
post Jan 27 2015, 06:11 PM
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I'm beginning to come of the opinion hat the "dark ribbon" feature leading from what now appears to be the prominent southern basin to the west to a second, smaller basin is an albedo feature. It is too far south of the apparent basin rims to be a simple shadowing, and doesn't completely follow the basin rims. Also, if it's shadowing, it seems to be from some type of central peak units rather than from the rims, and stretches across the rims between two basins, which I wouldn't expect even complex central peak or ring structures to do. And, finally, it doesn't seem to be discontinuous as it tracks between the two basins or north-west to the "Y-shaped" bifurcation. (These details are visible, if barely, in the Hubble images, as well.)

Of course, this could be the "Martian canals" effect, where fuzzy unresolved details seem to grow into continuous linear features by dint of the mind's eye. I mean, it could be a chasm feature that has penetrated and degraded the basin rims -- after all, in some of the recent images, it's extent almost makes it look like a crack in the world defining an off-equator circumferential chasm system.

The one statement anyone can make for certain is that we'll know far better in a few weeks.

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MarsInMyLifetime
post Jan 27 2015, 06:28 PM
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Can spalling occur on a body this large? From Phil's versions, the ringed terrain has the appearance of being popped out rather than filled with the usual slumped regolith. I'm prepared to be surprised and corrected with each update of resolution and context, but had to at least muse about processes that create hollows.


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Phil Stooke
post Jan 27 2015, 08:05 PM
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Comparison of the HST map (note it's recentred here to avoid splitting the Dawn map area) and a cylindrical projection of the three images I posted earlier.

PLEASE note that my registration is not well controlled, and you really have to wait for the Dawn team to produce an accurate map. This is just to indicate roughly what a map might look like when we do get one.

Phil

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tedstryk
post Jan 27 2015, 08:20 PM
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Probably superficial, but with its bright spot and dark, presumably cratered (at least where we're looking) surface, I'm having flashbacks to Umbriel (in the attached image, Ceres is on the left, Umbriel on the right).
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elakdawalla
post Jan 27 2015, 08:28 PM
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Wow, that's pretty spectacular similarity smile.gif


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Habukaz
post Jan 27 2015, 08:39 PM
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That bright spot on Umbriel in that frame is the circular feature at the top in this image, right?


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DrShank
post Jan 27 2015, 08:40 PM
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QUOTE (elakdawalla @ Jan 27 2015, 02:28 PM) *
Wow, that's pretty spectacular similarity smile.gif


yeah. too bad we never got better on Umbriel or we could test that hypothesis...


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0101Morpheus
post Jan 27 2015, 08:46 PM
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Perhaps this is an indication that Ceres formed beyond the snow line?
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