RC2 images are now out on the Photojournal: http://photojournal.jpl.nasa.gov/keywords/dp

Wow! Some big basins. Almost like the flats on Triton, though it must only be a skin-deep resemblance....

Worth the wait!

Max Planck Institute have now added a press release with new images.

Two glimpses of dwarf planet Ceres.

http://dawn.jpl.nasa.gov/feature_stories/B...r_Companion.asp

Oooh


I like the sound of that.

And also still too small to resolve:

The final albedo must get higher and higher as the predicted size of the spots drops, right? Things are getting very intriguing....

Here are Celestia previews of those two frames, just to give a sense of the geometry:
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To be honest, I'm now more interested in this impact basin. Looks fresh, but it has very muted topography. Maybe it was big enough to reach a liquid layer beneath the crust.

As I expected a Mimas-like surface I'm really surprised to see that some regions are far from being saturated with craters. And these bright spots... This dwarf planet gets really interesting !
Can't wait to see more next Monday, during the NASA briefing !!

There seems to be a rush to claim the big basin as young. That's not correct. Look at the craters inside it - at least the spatial density of larger craters in Mare Imbrium. The basin is old, it's erased a background of large craters and is filled with plains, but since then lots of mid-sized craters have formed. This is quite similar to lunar crater distributions (in general terms) so the chronology can't be very different.

Phil

100% agree with you Phil !
I think that some experts like Hartmann, Neukum, Salamunićcar, Barlow, etc... are excited to see the next images that will be taken at higher resolution to refine their size-frequency distribution (SFD) of impact craters. No doubt that Ceres seems to be one of the perfect planetary bodies (not too big and not too small) to calibrate crater-SFDs

It's a bit surprising to me how shallow the big crater/basin seems to be. Also it now seems very unlikely that Ceres has anything resembling Tethys' Ithaca Chasma (there were some speculations on that here earlier on). It probably was simply an albedo feature plus shadows within crates in the earlier, lower resolution images.

The bright spots are interesting. To me they simply look like fresh ice that has been exposed by impacts but apparently they might be something else.

True, young and fresh certainly are relative terms...


Most still look like fresh ice exposed by recent impact, just by small impacts. The one that kind of looked like a five-legged creature in last week's view now looks like a lot like the ray crater in Anguta, Rhea.

There's a new Dawn Journal with an updated table.

Keep in mind that the RCs and OpNavs follow some or all of Ceres' 9-hour rotation, so they can, of course, begin on one day and end on another, and a photo release could come from either day.

Gerhard Neukum passed away last year, but is no doubt as excited as the rest of us on whatever astral plane he now inhabits.

Isn't the easternmost ("rightmost" in the the earliest OpNav images) part of those apparent linear features the apparently relatively smooth terrain seen in the right frame in today's release?:



(south should be to the bottom; image rotated 90 degrees clockwise from the original)

Not particularly valley-like (and not particularly un-valley-like, either), but to me it looks like it could still be a real thing. It looks considerably smoother than the terrain at the same latitude to the east in the same frame.

In the absence of the full rotation sequence, it seems hard to judge whether it's a real feature or not.

There might be a gentle dpression there but if so it's not nearly as clearly defined as Ithaca Chasma.

What the heck is up with the limb in the non "cropped" images? It's as if the images were magnified a very small amount using a nearest neighbor algorithm.

No disagreement there.

Good spot! And I'd call it valley-like, though not graben-like. There's definitely a broad low depression there.

I do get the impression there's less geology going on here than even Vesta, but still plenty to study.

Also, did anyone notice that the huge flat crater has a small sharp crater almost bullseyed in the middle, like in Caloris, only proportionally bigger? It's an odd coincidence, but cool-looking!

I am pretty surprised at the non-cratery features on Ceres. Looks like there are some low, large mounds and maybe a Y-shaped valley in that basin, with another wider valley entering from the bottom.

JPL article updated this time with an image of the main bright spot(s).

http://www.nasa.gov/jpl/dawn/bright-spot-o...n/#.VO4LGeFze0j

Wow, that really does stand out!

That's a great new picture!

Here's a different kind of reprojection, turning perspective (nearly orthographic) into something vaguely resembling stereographic. Don't trust the geometry - this is just to show limb areas more clearly.

Phil

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Wow!! It's so bright that it's as if Ceres is emitting light ;-).

My guess is still that this is fresh ice exposed by a (very?) recent impact but of course something else than that would be far more interesting so I'm hoping I'm wrong.

There are grooves visible in that latest pic.

Between all three pictures, that's getting close to global coverage, right? The latest journal also states some pertinent facts about orientation, such as much less seasonal issues to worry about then at Vesta:

http://dawnblog.jpl.nasa.gov/2015/02/25/da...al-february-25/

For the bright spots, impact melt is a possibility. Sublimation weathering takes its toll, but those features are young.
For the mare-like big crater, There seems to be some lumpiness in its floor, so whatever filled it (volcanism, plastic relaxation, etc.) has been tweaked (global shrinkage?). As far as the age of that feature, it could easily be LHB, but the detailed crater counts will help date it. Gravity measurements from orbit will also help. The impact evidently occurred early enough that the interior of Ceres could cause it to relax somehow, plastic, liquid or volcanically.

Yes it do indeed look very shiny, which suggest it's still bright enough to saturate the CCD's of the camera. And so might be even smaller than what it appear.
They do show at the bottom of the crater, so that recent impacts have exposed ice is indeed the most likely explanation - and I'd be all happy with that.
That would give an indication of the outer dust shell which one hypothesis say Ceres should have.
Yet even so they do speculate also on the JPL page: "This may be pointing to a volcano-like origin of the spots.." hinting at the possibility of one ice volcano, but if so it would have had to be relatively recent and honestly cannot imagine what would have provided the energy.

Anyhow, at that very same image I can see 2 linear features near the limb at about 5 o'clock, and at the right image released earlier today at center, that bright area do not look circular at all to my eyes - so even though Ceres is a bit different than I expected, it appear to give us quite a list of geological features to look into the next couple of months. =)

Here are all three images with their approximately original resolution (assuming a polar diameter of 909.4 km):
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And here is the Celestia perspective (note that the bright spot seems to be too far north in the previous maps posted here):
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With these three images we should more or less global coverage.

Looks like it's located dead center of a "crater" which seams quite unlikely (except if the impactor was called Opportunity )

The main part of the Bright Spot appears to be very close to centre in its crater, which suggests some connection with a central peak?

The appearance of the various bright spots is very sensitive to phase angle and any stretching/levels adjustment in the images, as you can see by identifying bright spots, many of which were saturated in the previous release, with the new release:
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Some of the previous bright spots are essentially invisible in the new frame.

It's interesting that the secondary bright spot is almost in line with the first one and the sun angle. Could it be sunlight scattering or reflecting off a plume from the bright spot? The plume would have to be pretty high, given the viewing geometry, but still...

As a couple of others have noted, there's some really interesting stuff going on with the grooved terrain to the south and east of the bright spot. Just a little more resolution would be really helpful -- hopefully the whole rotation sequence will be posted, so image stacking could tease-out the details.
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There's also a curved ridge to the left-bottom of the bright spot crater.

Not necessarily unlikely if the large old impact and the small new one both played a part in making the bright spot: the former collecting a buried 'puddle' of relatively clean near-surface ice and the latter exposing it.

Those grooves look like they could be secondary crater chains from an impact basin. Do they line up with any known or suspected basin?

And those white spots. They are so.... nonrandom.

How so non-random?

No one has posted a resampled version of the third image. The released image appears to be trivially oversampled 2x. So by subsampling (without smoothing) by 1/2, you recover close to the original image. Then I've supersampled (Lanczos) 4x. Here's the result:
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By nonrandom, I mean two anomalously bright spots appearing in only one place (or few places) on an otherwise drab surface. Better yet, one spot appears to coincide with the central peak of an ancient crater. I would expect a number of similar features scattered around the surface.

With such a small number of spots, I wouldn't be thinking about randomness or otherwise just yet.

Phil

I'm trying to understand the "uncropped" images they released. I'm don't think they mean "uncropped", since they clearly aren't showing the full 1024-pixel-square FOV. Maybe the originals were windowed? I thought that maybe they meant "unenlarged", but if you look closely at the photos you'll see that there is something wonky with them -- there are several lines of pixels (some horizontal, some vertical) that have been repeated. Either there's a glitch in the camera, or there are some missing lines that were interpolated, or the image has been very slightly enlarged with nearest-neighbor sampling. It's bizarre.

I agree that the bright spots appear non-random. You need a (most likely random) recent event to break through the ubiquitous dark surface covering but whether this exposes dark or light subsurface must depend on more ancient events at the same location. We saw both light and dark materials exposed on Vesta by impacts and landslips on slopes. I think that Ceres, by providing more such data points, should enable the story of all this to told at last.

Continuing with my previous post: the "uncropped" images have been enlarged from the original by about 2.5 percent with nearest neighbor sampling, resulting in four vertical and five horizontal duplicated lines of pixels in the images. Here's a before and after comparison of one of the two images after taking those extra lines of pixels out.

Maybe they come out of a set of images where they created a movie where they tried to make them all equal in size, since Dawn slowly approaches Ceres during RC2, rather than pulling them from the raw images?

That sounds plausible. I hate that I have to keep explaining to people on Twitter that NASA has not blurred these photos; that they started out as lower resolution and have been enlarged.

The bright spots make me wonder if there's something like thermal segregation going on. On Iapetus, roughly half the surface is bright and half dark, and thermal segregation makes the "rich get richer" (the bright gets brighter and the dark gets darker). Maybe on Ceres, there's thermal segregation but the bright is only a tiny fraction of the surface, evacuating whatever dust might cover it through thermal processes driven by solar heating.

There's an interesting comparison set, potentially, with Ceres, Callisto, and Iapetus, all of which have some mixture of dark and icy surface. Those three rank in terms of rotational period exactly the opposite of how they rank in proximity to the Sun. Iapetus has extremely long days, but a dim Sun 9 AU away. Callisto has a shorter day, but a considerably brighter Sun. Ceres continues the trends: A very quick day, and yet more solar heating.

On Iapetus, we have full-blown thermal segregation, with the cold half seemingly stealing whatever ice sputters from the warm half.

On Callisto, ice sputters away, but doesn't particularly gather anywhere. Though on Ganymede, icy gathers on the coldest slopes near the poles.

On Ceres, a few very bright areas (ice, one supposes) are staying bright, and there's a seemingly binary distinction being maintained: Ice or no ice. Is ice sputtering away from the darker ~99% of Ceres as it does from the darker 50% of Iapetus? It's the rareness of the bright patches that stands out. If Ceres is geologically inactive and impact craters of different ages are the only features, why would only a few of them have this rare property, versus Callisto where all sufficiently large/recent craters show ice under the dirty stuff?

Agreed - the captions should state whatever enlargement has been done, the way Casini, eg, does with their image releases.

For the "uncropped" images, there are probably many possibilities. Maybe someone (bizarrely) reduced enlarged images rather than starting with the original resolution images. (Maybe the enlarging was by percentage, but the reducing by pixels, to account for the 2.5% discrepancy.)

Too many "ifs" for me : better ask Velma to solve this mystery !
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Yes, that's what I was getting at. A single spot would be 'randomly distributed'. I should have gone with 'anomalous'.

So either the spot was formed by a relatively very recent event, or there was some process unique to that location.

I saw you logged on and I'm really glad you gave us your thoughts on the Ceres images. I too thought about separation of light and dark on Iapetus but I don't think that works here. At Ceres I think we have sublimation of exposed ice but no significant redeposition. Also the light patches don't seem to be related either to slope as on the Voyager mountains, or latitude as on Iapetus more generally and Ganymede. Somebody mentioned salt as a possble long-lasting white surface material. I'm thinking of a subsurface consisting of dirty ice in some places and clean but salty ice in others. Impact into the latter and you get a bright spot consisting initially of ice but rather soon forming a salt crust

The major bright spot is 15km wide and lies at the bottom of a rather deep 95km crater and is brighest (freshest) at its centre. The crater is deep relative to others because it formed after the ice shell grew thick enough to support the floor without flooding. Nevertheless, its age is likely to be in the billions, rather than millions of years. If the spot was a benign patch of material, ejecta from elsewhere would have covered it on geological time scales, so we can be confident there has been some sort of activity there. The fact that the dark ring visible in lower-resolution images is offset from the crater, is further evidence of activity. Perhaps this is an active or sporadic geyser shooting out to the right - the water turns instantly to ice and lands at that elongated spot within the crater. The dark ring might be a consequence of soil having been displaced.

The extensive network of crosshatched grooves is likely due to expansion of the ice shell as it froze, but larger rift valleys seen in earlier images seem to be associated with major impact basins.