I find myself in that camp too, although there are well placed scientists invoking volcanic processes so I don't know. . . It's easy to imagine an impact triggering landslips nearby so maybe that's what we're seeing in some places at least.

Looking at the animation for spot 5, I'm tempted to see the spot at the crater's center as being a depression. On both the right and left sides of the white spot, in the image, there appears to be a ridge or crater rim a couple of pixels high.

I would think it was a fresh crater that had penetrated into a watery/icy region, then filled up with fresh ice, but why is that tiny spot so conspicuous on the entire asteroid? Why just the one place? The rest of Ceres is so battered, it would make more sense to me if there were many things like spot 5. I know there are some bright areas, but 5 really jumps out.

To me, that is what is most intriguing about it. If it is merely bright stuff beneath the regolith, I'd expect something more like Callisto.

Just trying to map out the bright areas:

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Crater floor fractures?

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Is that rift in any way radial to the mountain/'volcano' thingy? Could they be associated?



Why am I thinking Tharsis?

P

Too soon to tell unfortunately. Impacts can create rifts too, and Ceres has had an awful lot of them.

I don't know if I can think of a single example of an impact producing a rift. The grooves of Phobos are often cited as such, but that's a hypothesis, not a certainty, and other possibilities have been suggested (impact of Mars ejecta, jointing during excavation from a larger primary, or drainage between blocks in a rubble pile, for instance). The "Imbrium Sculpture" pattern of radial lineations on the Moon is now regarded as due to ejecta scouring and deposition, not structural in origin as suggested decades ago.

It's much more likely that this feature is a chain of secondary craters. Think Rima Schroedinger or the Rheita Valley on the Moon.

Phil

Has anyone noticed in the RC3 movie, small hills (cones) at the bright spot near the large mountain, and that they and the mountain are both on a fault line, and that this system of faults extends through the crater with the brightest spots of all?

John

The crater Turgis and the 'tiger scratches' on Iapetus came to mind as something to compare the rift on Ceres to. The association of the crater and the 'scratches' on Iapetus might be coincidental, and AFAIK, there seems to be only one rift seen on Ceres and IIRC, there are 3 'scratches' noted on Iapetus.

There are similar valleys on Iapetus associated with the large basin Falsaron, NW of Turgis. All of these are secondary crater chains. See also Vallis Bouvard and Vallis Inghirami on the Moon. None of these are tectonic rifts. It is really not a good idea to use the term rift with its tectonic implications.

Phil

The rifts around bright-spot crater are more or less parallel with rifts to the south (red):

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These were visible in earlier images:

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They seem to be associated with the resurfaced area shaded in yellow. I thought these features all resulted from the large impact (just beyond the terminator), but now I'm not so sure.

The green lines to the left and upper left of the 'Spot 5' area are definitely related to crater chains.
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The lower right area could be rifts. I think it could be possible that the spidering lines near 'Spot 5' could be related in some way to whatever has gone on in that area.
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Maybe the liquid ocean has most recently only existed under this section of the crust and each time a very large object impacts, it oscillates the water below cavitates, similar to if you strike the top of a beer bottle and it causes the bottom to blow out.

edit: terminology

Remember that tectonic cracking of a crust can express itself as chains of endogenous collapse pits. There is at least one major rift in the pictures above that expresses itself as semi-arcuate with straight, steep sides at one end and devolving into chains of craters as it becomes narrower and less distinct at the other end.

Let's wait for closer imagery before we jump to conclusions, eh?

Please, continue to discuss and speculate...

I am a big proponent of impacts transferring energy to the opposite side of a body and causing eruptions. I don't have any iron clad examples - this article has a nice visualizations but is earth specific though mentions applicability to other bodies and a crater on Mercury. http://www.princeton.edu/main/news/archive/S31/90/32S94/

Anyways I wonder if it's more than a coincidence that one of the largest more recent appearing craters is opposite the mountain, and close to some of it's adjacent rifts. Maybe Ceres was mostly liquid when it hit and caused an antipode eruption?

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Piazzi (contrast enhanced):

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There is an intriguing mix of light spots and dark mottling around the southern side of the large crater. Since this area may coincide with elevated water vapor levels, it will be especially interesting when the high-res images come in.

Oddly enough, there hasn't been any mention of this feature lately.

Thank you Zelenyikot, your image animation do indeed suggest it is conical shaped. If it turn out to be the case, we're in for a few raised eyebrows and we will have to lobby to have it named Saint-Exupéry. =)

Sorry to be Off Topic here for a second [moderators feel free to move this potentially contentious post elsewhere] - but I think it's important to future discussion in an unmatched year of recent unmanned exploration: comet CG, Ceres and Pluto! :

I’m a newbie so don’t have the years of past precedence on these forums, so defer to the senior members, but I signed on because this appeared to be a unique place to discuss informed hypotheses and share in the exploration thrill that we all know that unmanned missions allow for.

If we wait for the official scientists to produce their peer reviewed papers months or years in the future - what’s left? just commenting “ah ha that’s what it was…” I fail to see the fun in that, and the fun aspect I suspect is what draws many to these forums. If we aren’t allowed to reasonably speculate - I would argue a science news feed would have similar value, and diminish the unique quality these forums allow for - which is exploration camaraderie (at least as much camaraderie as the internet allows for).

If I am off base here - senior members please set me (and all us newbies) straight.

Truly sorry to digress from the exciting topic at hand - but it's an important point I think for what gets commented - especially during the next 6 months of heavy first time exploration.

There is a difference between observations; inferences supported by evidence; and proposing things that are physically impossible, dramatically contradictory to the conclusions already made by scientists, much less likely than more reasonable explanations, and unprecedented elsewhere in the solar system. The thing that makes this forum great is the fact that we permit only well-grounded speculation; it means active scientists and engineers can enjoy discussion here.

dvandorn wasn't warning anyone, just expressing an opinion.
Note what Bill Harris said in the post following dvandorn's:
Please, continue to discuss and speculate...

And then there is this subtly shaded area to the north and east of the bright spots (contrast enhanced):

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Most interesting to me is the sharp boundary between albedos that seems to extend north (and southeast?) from the primary bright spot. This appears to be independent of topography. I have a process or two in mind, but will wait for higher-res images....

Is this the same as the dark halo surrounding the bright spot ('Region A') visible in pre-Dawn observations?

----------

One more thing to mention....

So we have two areas ('Piazzi' and 'Region A') that turn out to be clusters of bright spots (of varying size and extent) surrounded by subtly shaded areas. These regions also happen to coincide with areas with elevated water vapor levels:

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Again, mere coincidence has to be assumed until more data comes in.

Maybe feature 5 is the remains of a shallow angle, low velocity impact...? Great catch, Gladstoner!

...the remnants of the original covering of the bright spots are the ejecta blanket to the north and northwest. The bright spots are the underlying layer of Ceres (composed of?).

In this (unproven) scenario the impactor was split just before impact.

It would require lower mass, lower velocity impactor at a much steeper angle than I had originally theorized but it seems to fit the available evidence so far. I suppose the bright spots could be the impactor and it would still fit the data.

That it's inside a crater is just coincidence, or expected given the large number of craters.

Andy

Oh, yes -- I love to speculate. I sure didn't mean to quash speculation! I was encouraging it, I thought, by bringing up reasons other than just long-string impacts for the formation of crater chains.

I guess we've been pushing the "let's wait for better pictures" line on Dawn's approach to Ceres so much, it's a little hard to stop. We are now seeing sufficient detail to start some serious speculating. So, I take it back -- let's not wait for better pictures, let's see what we can see in the current ones.

In that spirit, I want to share a general impression from the pictures to date, though it's something I've noted before. And it fits in with a lot of the other observations.

It looks to me like Ceres has been through several epochs of what I'm beginning to dub, in my head, as "splash resurfacing." I keep thinking I'm seeing a lot of overlapping units, all of which are cratered to some extent, but all of which also appear to cover over much older cratered terrains. The smoothest areas seem to be where two splash-emplaced units overlap, where one was relatively young when the second was emplaced. There seem to be quite observable units, classifiable by superposition.

I'm getting a sense of a body that, upon impact, splashes rather than creating the type of ejecta we're used to seeing on Earth, the Moon, Mars, etc. We're talking impacts large enough to form what would be basins on larger, rockier worlds. On Ceres, such events seem to have rebounded and relaxed, perhaps to the point of being impossible to recognize after a gigayear or two, so you don't see "basins," but that's the kind of impact I'm thinking about.

Those impacts look to have created sheets of material that fly around Ceres for a while and then emplace themselves, perhaps in patterns and locations far enough removed from the impact to make it difficult to work resurfacing events back to their impacts.

Some of the squirrely arcuate ridges and gorges may be the result of multiple splash sheets created by a given impact interacting with each other before they fell back down onto the surface. After all, Ceres is a small body, so ejecta can fly around that little world a few times before finally re-impacting the surface.

I'm wondering what exactly happens when impact heating from a Cerean "basin-forming event" is very rapidly infused into gigatons of relatively warm ice...

Just to step in with a mod opinion here: Speculation on new observations of a never-before-seen world is of course encouraged; that's half the fun!

Please take time to review the Rules & Guidelines section, and let's keep it confined to the realm of the possible within realistic constraints. Also, please avoid rants & idee fixe's; those become very tiresome very quickly. Our intent as always is to increase the signal-to-noise ratio of the Forum, so please keep that in mind.

Thanks!

There's enough evidence in the RC3 images to make some preliminary conclusions on the unusual features we see.

MOD NOTE: No, there isn't nearly enough evidence yet to draw conclusions. Currently there is an extremely limited amount of data which may be used to formulate very tentative hypotheses which will be accepted, revised or discarded based on additional evidence and critical review. Key difference.

EDIT: To avoid misinterpretation, the gist of what I failed to convey properly in my first line follows.

I see enough evidence in the RC3 images to comment on what I believe the unusual albedo features are and speculate on how they formed.

1. The extensive grooves represent deep cracks in the crust, rather than crater chains from secondary impacts.

2. The spots are volcanic cones associated with rift valleys and fault lines, rather than craters exposing more reflective material beneath. That should become obvious to all when Survey Orbit images are released in June. The vents gradually expel cold ocean water, as a safety valve to equalise the pressure caused by expansive freezing on the underside of the ice crust. The water oozes out and freezes or falls as snow, before sublimating and leaving permanent deposits of salt behind on the surface. The mountain visible since February appears to be the largest such structure on Ceres, but is dormant or extinct judging by the dust gathering on its summit. However, the brightest spot/s could well be active and have ice close to their vents - something on Ceres is producing enough water vapour to be detectable from Earth.

3. The dark patches of chaotic terrain are also associated with fault lines. They probably represent sudden flows of rock-bearing mud, flooding out when major impacts occur elsewhere on Ceres and oscillations in ocean water pressure force some plates to gnash and grind against each other. The grooves become indistinct there because of that flooding. The southwest rim of Piazzi crater and the northeast rim of 'bright spot' crater are obvious examples of this, but there are others in the southern hemisphere we haven't seen in detail yet. I won't be surprised if all such regions have grooved terrain and volcanic cones associated with them, because they represent areas where water can most easily reach the surface.

I come to this site every day and even though I have been a space enthusiest for 45+ years, I rarely make comments because of the high calibur of the regulars, I would have little to add!

Dawn will pause its ion thrusting tomorrow to take navigation pictures of Ceres per the status updates. No mention of which areas of Ceres that will likely be photographed.

Speaking of 'fun' speculation, I'll give it a shot, with heavy emphasis on 'fun' at this point....

Some scientists have said there *may* be evidence of cryovolcanism on Ceres. If that turns out to be the case, then is it possible the darkish areas surrounding the bright spots could be plume deposits?:

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I can't help but be reminded of these features on Triton:

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(Some of these even have darkish material eminating from brightish spots.)

The materials and processes on Ceres would be quite different than those on Triton, though, and there would be no atmosphere on Ceres to carry the particles down wind. Extensions of a Cerean plume deposit in certain directions would likely be due to the configuration of the conduits and vents.

Again, the usual caveat: This 'theory' could very well be ejected into a plume of dust as soon as higher-res imagery comes down.

That's the only explanation that I can think of based on the visible details at this resolution.

What is the direction of Ceres rotation in these images?

Triton's plumes are associated with the polar caps. There is a physical model for sublimation beneath the surface of the ice, and explosive release of gas pressure that brings up dust and such with it. There were a few active plumes and many streaks from past activity, so the geysers are a widespread phenomenon.

But the lack of polar caps or obvious surface ice deposits on Ceres would suggest (possibly require) a different mechanism. Any similarity in appearance may be coincidental. And I'm still really bothered by the contrast with essentially the entire rest of the surface, which appears rocky, with deep craters not obviously revealing high-albedo features indicative of ice deposits or ice layers. I don't recall seeing prominent "mud splats" like we see on Mars from areas where material appears to have flowed out of craters. Yet in this one place, a starkly different thing is found. The features in this crater appear to be quite different at least in appearance and size than other "bright spots" found on Ceres. If anybody has the time to do a compare/contrast, quantifying the differences, that would be very interesting. But I have grades due Monday...

Just a quick clarification that Triton's plumes & deposits are often found at low latitudes on this cylindrical projection, so I'm unsure why polar caps are being mentioned. Namazu Macula shown by Gladstoner is near the equator. Is the polar cap large enough to cover the entire southern hemisphere? I had heard that solar heating could help power the geysers that would be present at lower latitudes, though if we are near the summer solstice signficant solar heating would be present at all southern latitudes.

Left to right.

I believe the area you quoted is within the polar cap, which is very widespread. Contrast that terrain with the bluer terrain above it.

It might be interesting to note that although Ceres has no visible (obvious, anyway) atmosphere in the images returned thus far, that does not necessarily mean that it does not have an atmosphere in a meaningful sense of the word.

Recently, there was published a paper about what the scientists thought could be the detection of an atmosphere on Callisto, a world that in images does not look at all like it has an atmosphere. If I understood it correctly, the presence of this atmosphere would mean that Callisto possibly could have some sort of winds. Now, we already have a detection water vapour around Ceres, meaning that the suggestion Ceres could have an 'atmosphere' (in the sense of the word in the blog post I linked to) shouldn't be that far-fetched.

That said, I suspect there is a less exotic explanation for that darker area; a feature that I have been keeping track of for quite some time now.

In this context, too, it seems relevant to bring up the comparison with a certain crater on Mercury:




Around this crater, of course, the apparent darker area is found around all of the crater rather than just some of it. Here's a lunar crater with the asymmetry property (even complete with some bright stuff!):

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Another take on the latest Ceres series, in 3D:
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Full-res here, and slowed down a bit: https://farm9.staticflickr.com/8798/1782392...4fb7dd598_o.gif

And a full-res of the dwarf planet spinning little faster: https://farm9.staticflickr.com/8761/1766330...90077a52f_o.gif

Not sure why lighting shifts in some frames, thought I did each stepp the same. it pops out of the screen, which is how it renders when putting it together the quickest. It might be cool to have it recessed, as if peering from a spaceship window, but would take a bit more time. Such a lonely, mysterious, pretty little world! That volcano-like structure is as strange as the white spots. Enjoy these days of discovery!

The first image is of a crater named Sander, which has bright "hollows." From looking at the movie of bright spot 5 posted a couple of pages ago, it sure looks to me that the white patches in spot 5 are in hollows. Time will tell. In digging around, I found an interesting article discussing the discovery of the bright hollows on Mercury, including those in Sander. It contains a very high-res image of Sander as well.

http://messenger.jhuapl.edu/the_mission/pu...lewett.2013.pdf

The features in Sander may be from some sort of sublimation-related process, at least that was the speculation at the time of the article. The visual similarity between Sander and bright spot 5 is pretty striking, at fairly low resolution. I wonder if we'll ever get a shot like the high-res image of Sander in that post. But thanks for posting the Sander image, it was enough to remind me to be skeptical about whether ice has any role in spot 5. What a vexing feature!

The largely resurfaced region south of the crater with the bright spots is devoid of medium to large craters, but curiously is peppered with more small craters than older terrain.
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Suppose mud flows carrying giant icebergs covered this area; shouldn't frozen mud quickly develop its own insulating layer of dust, but pits will be created as the relatively pure icebergs sublimate away? Maybe the outer 10km or so of the crust is made of frozen mud, with pure ice further down. That would explain why there's no evidence of ice having been exposed in larger craters and causing erosion there.

Are those small craters or are they remnants of internal gas vents?

It is interesting how many "pieces" the right side bright spot has turned into. I think we've already seen an image where the main bright spot is at least two separate clumps. These could be very small and reflective mounds of material if it is impact related or very small outgassing pockets if it is an active area. Impact remnant still works for me at this resolution and doesn't require internal heating.

Andy

Just to keep other causes in the discussion, we can't rule out some not-yet-obvious circumstance leading to secondary ejecta craters. But I do think the highly localized borders for some of these pits does speak to flows rather than ejecta. And other volatile materials than water could be at work as well. The Sander Crater example is similar only by possible mechanism; the soluble material there may have had a much higher temperature of sublimation/vaporization than water. In fact, I've seen solder blobs that pulled into such shapes; other volatile materials had nothing to do with the puddling behavior of the melted material.

Yep, the bright spot is in the latest navigation images (OpNav 8). Image quality is pretty poor, though.

For convenience, the bright spot 8-fold magnified, and brightness-stretched in a nonlinear way, darker parts mapped to black:
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Personally I'm more than happy to accept lots of JPEG compression artifacts in exchange for relatively quick release of new images. So far Ceres has been so much better than Vesta in terms of image release.

We are finally at the point where we can't get all of Ceres in a single frame, so quality is amazing! It wasn't that long ago were were stretching to death 20 pixel wide images.

It's puzzling, though, that the associated TIF images have the same JPG artifacts. One would think they would use unaltered images for the ~1-meg files.

I thought I'd inject a comparison between Ceres' bright spots and albedo patterns that we've seen up-close on Phobos. Eg,
http://photojournal.jpl.nasa.gov/catalog/PIA10368

Phobos is of comparable distance from the Sun, and is also dark with bright spots. We can see that the bright areas underlie the dark surface and are exposed by combinations of impact cratering and downslope flow. We also see that craters within craters can create arbitrarily fine detail. We also see asymmetries that might not, a priori, be expected: Bright spots at certain places on a rim, but not in others, and bright patches where two causes of incline add (e.g., the upslope wall of a crater within Stickney), but no bright patches where two causes of incline cancel out (the other side of that crater within Stickney).

Overall, there is a simple layering of dark over light, and physical exposure of the ice happens for two simple reasons (impact and downslope mass movement), with anisotropies in topography causing boundaries that appear complex.

This seems like a prominent model to consider for Ceres' bright spots until better observations show the nuances of the bright spot boundaries.

It's possible that they were returned as lossy-compressed images. These were opnavs after all, needed more for navigation than for science, so fine surface details aren't as important as seeing where the limb is. I know with Cassini we have the option to use that or lossless compression. I always use lossless compression because Titan's atmosphere makes my data blurry enough...

I thought that might be the case, but the images in the recent animated GIF appear to be unaltered, while images selected from the same sequence and released in TIF and JPG format are degraded. A comparison, from left to right, are GIF (movie frame), TIF, and JPG:

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I'm grateful they released that movie in the original quality.

It's horrible but true that the TIF versions of images at Photojournal are sometimes made from JPEG originals. It was probably provided to JPL by the FC team as a JPEG. Now, JPL could have just grabbed a still frame from the animation and posted that instead, but on missions there are agreements about different organizations having to post the same images at the same time, so it's not something they would ordinarily do.