Dawn approaches Ceres, From opnav images to first orbit |
Dawn approaches Ceres, From opnav images to first orbit |
Jan 27 2015, 03:25 PM
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#121
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Senior Member Group: Members Posts: 1079 Joined: 19-February 05 From: Close to Meudon Observatory in France Member No.: 172 |
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Jan 27 2015, 03:26 PM
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#122
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Member Group: Members Posts: 656 Joined: 20-April 05 From: League City, Texas Member No.: 285 |
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 Edit: Incidentally, what's up with the apparent Moire pattern in the animation? |
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Jan 27 2015, 03:34 PM
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#123
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Senior Member Group: Moderator Posts: 3230 Joined: 11-February 04 From: Tucson, AZ Member No.: 23 |
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. -------------------- &@^^!% Jim! I'm a geologist, not a physicist!
The Gish Bar Times - A Blog all about Jupiter's Moon Io |
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Jan 27 2015, 04:11 PM
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#124
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Administrator Group: Admin Posts: 5172 Joined: 4-August 05 From: Pasadena, CA, USA, Earth Member No.: 454 |
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. -------------------- My website - My Patreon - @elakdawalla on Twitter - Please support unmannedspaceflight.com by donating here.
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Jan 27 2015, 05:38 PM
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#125
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Member Group: Members Posts: 495 Joined: 12-February 12 Member No.: 6336 |
@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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Jan 27 2015, 05:49 PM
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#126
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Solar System Cartographer Group: Members Posts: 10145 Joined: 5-April 05 From: Canada Member No.: 227 |
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 -------------------- ... because the Solar System ain't gonna map itself.
Also to be found posting similar content on https://mastodon.social/@PhilStooke NOTE: everything created by me which I post on UMSF is considered to be in the public domain (NOT CC, public domain) |
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Jan 27 2015, 05:59 PM
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#127
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Member Group: Members Posts: 207 Joined: 6-March 07 From: houston, texas Member No.: 1828 |
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 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. -------------------- Dr. Paul Schenk, Lunar and Planetary Institute, Houston TX
http://stereomoons.blogspot.com; http://www.youtube.com/galsat400; http://www.lpi.usra.edu/science/schenk/ |
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Jan 27 2015, 06:11 PM
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#128
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Senior Member Group: Members Posts: 3419 Joined: 9-February 04 From: Minneapolis, MN, USA Member No.: 15 |
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. -the other Doug -------------------- “The trouble ain't that there is too many fools, but that the lightning ain't distributed right.” -Mark Twain
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Jan 27 2015, 06:28 PM
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#129
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Member Group: Members Posts: 148 Joined: 9-August 11 From: Mason, TX Member No.: 6108 |
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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Don |
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Jan 27 2015, 08:05 PM
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#130
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Solar System Cartographer Group: Members Posts: 10145 Joined: 5-April 05 From: Canada Member No.: 227 |
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 -------------------- ... because the Solar System ain't gonna map itself.
Also to be found posting similar content on https://mastodon.social/@PhilStooke NOTE: everything created by me which I post on UMSF is considered to be in the public domain (NOT CC, public domain) |
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Jan 27 2015, 08:20 PM
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#131
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Interplanetary Dumpster Diver Group: Admin Posts: 4404 Joined: 17-February 04 From: Powell, TN Member No.: 33 |
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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Jan 27 2015, 08:28 PM
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#132
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Administrator Group: Admin Posts: 5172 Joined: 4-August 05 From: Pasadena, CA, USA, Earth Member No.: 454 |
Wow, that's pretty spectacular similarity
-------------------- My website - My Patreon - @elakdawalla on Twitter - Please support unmannedspaceflight.com by donating here.
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Jan 27 2015, 08:39 PM
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#133
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Member Group: Members Posts: 423 Joined: 13-November 14 From: Norway Member No.: 7310 |
That bright spot on Umbriel in that frame is the circular feature at the top in this image, right?
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Jan 27 2015, 08:40 PM
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#134
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Member Group: Members Posts: 207 Joined: 6-March 07 From: houston, texas Member No.: 1828 |
Wow, that's pretty spectacular similarity yeah. too bad we never got better on Umbriel or we could test that hypothesis... -------------------- Dr. Paul Schenk, Lunar and Planetary Institute, Houston TX
http://stereomoons.blogspot.com; http://www.youtube.com/galsat400; http://www.lpi.usra.edu/science/schenk/ |
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Jan 27 2015, 08:46 PM
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#135
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Junior Member Group: Members Posts: 78 Joined: 16-October 12 From: Pennsylvania Member No.: 6711 |
Perhaps this is an indication that Ceres formed beyond the snow line?
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