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Unmanned Spaceflight.com _ Dawn _ Dawn's Survey Orbit at Ceres

Posted by: Paolo Jun 15 2015, 05:47 PM

daily Ceres picture from the survey orbit
http://dawn.jpl.nasa.gov/multimedia/images/image-detail.html?id=PIA19572

I started a new topic, as we are no longer in the first orbit phase

Posted by: RotoSequence Jun 15 2015, 06:21 PM

QUOTE (Paolo @ Jun 15 2015, 10:47 AM) *
daily Ceres picture from the survey orbit
http://dawn.jpl.nasa.gov/multimedia/images/image-detail.html?id=PIA19572

I started a new topic, as we are no longer in the first orbit phase


Do my eyes deceive me, or is there a dearth of central pit craters on Ceres?

Posted by: Habukaz Jun 16 2015, 04:54 PM

The http://photojournal.jpl.nasa.gov/catalog/PIA19573 has a nice perspective that shows some topography:



and of course, a nice view of a bright crater:



Also some dome-like structures visible in other places?

Posted by: Gladstoner Jun 16 2015, 05:01 PM

The other white-spot crater looks quite messy, but in a good way:


(Cropped image 2x, not resampled.)

It does looks like the impact scored a direct hit on an isolated pocket of the white stuff.

Posted by: climber Jun 16 2015, 05:44 PM

Danielle's experiment seams quite close to this: splash!

Posted by: Gladstoner Jun 17 2015, 01:17 AM

QUOTE (Habukaz @ Jun 16 2015, 11:54 AM) *
The http://photojournal.jpl.nasa.gov/catalog/PIA19573 has a nice perspective that shows some topography:


That is the row of three mountains seen earlier. A map of the general area (thanks, Greenish for the map):


Posted by: Jaro_in_Montreal Jun 17 2015, 04:28 PM

A different view of that pingo/volcano/whatever and more white stuff.....


Posted by: Gladstoner Jun 17 2015, 04:48 PM

FYI, the released TIFS have much better detail than the JPGs.




That mound just seems to have no rhyme or reason. If anything, it resembles a volcanic dome ( https://en.wikipedia.org/wiki/Lava_dome ).

Posted by: Habukaz Jun 17 2015, 05:02 PM

shield volcano is the word that comes to mind when I see that thing. I wonder how old it is (whatever it is); there are hints of what could be craters on its slopes.

Posted by: Gladstoner Jun 17 2015, 05:13 PM

The fossae bundle again:




The square arrangement of features is interesting.

Posted by: climber Jun 17 2015, 05:48 PM

QUOTE (Gladstoner @ Jun 17 2015, 06:48 PM) *
FYI, the released TIFS have much better detail than the JPGs.




That mound just seems to have no rhyme or reason. If anything, it resembles a volcanic dome ( https://en.wikipedia.org/wiki/Lava_dome ).

Same but with a wider perspective: https://twitter.com/nasa_dawn/status/611222468942934017

Posted by: Habukaz Jun 17 2015, 06:29 PM

The images at full resolution are as usual found at the http://photojournal.jpl.nasa.gov/keywords/dp and the http://dawn.jpl.nasa.gov/multimedia/images/. The Twitter account rarely provides anything unique other than some extra image description (like https://twitter.com/NASA_Dawn/status/610918025403891712 the bright crater (https://twitter.com/NASA_Dawn/status/610901239685984256) in yesterday's images as young) and status updates.

Posted by: Superstring Jun 17 2015, 07:55 PM

Are we sure that volcano-looking feature isn't a crater? Sometimes it's hard to tell if something is a mound or a hollow.

Posted by: Gladstoner Jun 17 2015, 08:03 PM

QUOTE (Superstring @ Jun 17 2015, 01:55 PM) *
Are we sure that volcano-looking feature isn't a crater? Sometimes it's hard to tell if something is a mound or a hollow.


Definitely a mountain.

QUOTE (Zelenyikot @ May 11 2015, 03:36 PM) *

Posted by: Mercure Jun 17 2015, 11:16 PM

QUOTE (Gladstoner @ Jun 17 2015, 06:48 PM) *
That mound just seems to have no rhyme or reason. If anything, it resembles a volcanic dome ( https://en.wikipedia.org/wiki/Lava_dome ).


Perhaps a tip of rocky core poking out through a globe of dust?

Posted by: Daniele_bianchino_Italy Jun 17 2015, 11:31 PM

QUOTE (climber @ Jun 16 2015, 05:44 PM) *
Danielle's experiment seams quite close to this: splash!


Yes climber :-)


I'm enthusiastic for new images, in particular for the Mouns..

.

Posted by: Habukaz Jun 18 2015, 08:20 AM

According to the https://twitter.com/NASA_Dawn/status/611313921589407744, the mountain is about 5 km tall.

Posted by: Daniele_bianchino_Italy Jun 18 2015, 11:51 AM

QUOTE (Habukaz @ Jun 18 2015, 09:20 AM) *
According to the https://twitter.com/NASA_Dawn/status/611313921589407744, the mountain is about 5 km tall.


I enjoy this...
i have supposed that this mount more 4000 mt Tall at the first image of May :-)
(in recently image i have supposeD 6'500mt tall, but I probably wrong)
it's possible compare at some italian volcanoes (5000 mt tall supposed):



Posted by: katodomo Jun 18 2015, 04:10 PM

QUOTE (Habukaz @ Jun 18 2015, 10:20 AM) *
According to the https://twitter.com/NASA_Dawn/status/611313921589407744, the mountain is about 5 km tall.

Personally i find that 70+-km long "cliff" in the center of that image just as, if not more interesting. How do you get that?

It's not a crater rim (unless we got some really serious erosion otherwise there), it's not some sort of "cave-in" depression below. What it looks like at best to me is tectonic activity folding it up, but uh... we don't get tectonics on Ceres, do we?

Posted by: Phil Stooke Jun 18 2015, 04:21 PM

Actually it is a crater rim, part of the biggest impact basin we have been seeing in several recent hemisphere-scale images, like this one:

http://dawn.jpl.nasa.gov/multimedia/images/image-detail.html?id=PIA19557

(note that image is flipped left-right, the new one is not)

Phil


Posted by: scalbers Jun 18 2015, 05:05 PM

Indeed it's good to look at the context to see the entire basin that raised rim is a part of. Here is an updated map, now with a second image from the survey orbit that shows a closeup of this raised rim and nearby conical mountain. In honor of this closer orbit the resolution of the map is now increased to 8K.



Full 8K resolution and polar views http://laps.noaa.gov/albers/sos/sos.html#Ceres

Posted by: Gladstoner Jun 18 2015, 05:15 PM

Now the lesser southern basin is being showcased:

http://photojournal.jpl.nasa.gov/catalog/PIA19575

Posted by: Daniele_bianchino_Italy Jun 18 2015, 06:29 PM

it'real this color images of CerES?




Posted by: vikingmars Jun 18 2015, 08:02 PM

QUOTE (Daniele_bianchino_Italy @ Jun 18 2015, 01:51 PM) *
I enjoy this...
i have supposed that this mount more 4000 mt Tall at the first image of May :-)
(in recently image i have supposeD 6'500mt tall, but I probably wrong)
it's possible compare at some italian volcanoes (5000 mt tall supposed):

Although not a volcano, Monte Bianco should be the same size ! smile.gif

Posted by: scalbers Jun 18 2015, 09:52 PM

QUOTE (Gladstoner @ Jun 18 2015, 05:15 PM) *
Now the lesser southern basin is being showcased:

Indeed this image fits in nicely to help map out the basins, including features such as the fossae bundle. Thus here is a quick updated map.



Full 8K resolution and polar views http://laps.noaa.gov/albers/sos/sos.html#Ceres

Posted by: Daniele_bianchino_Italy Jun 18 2015, 10:18 PM

QUOTE (Gladstoner @ Jun 17 2015, 06:13 PM) *
The fossae bundle again:




The square arrangement of features is interesting.

fantastic this Fossae. .
I Hope in a great resolution

Posted by: eliBonora Jun 19 2015, 05:07 AM

QUOTE (Daniele_bianchino_Italy @ Jun 18 2015, 08:29 PM) *
it'real this color images of CerES?


Hi there, is a bit of time that I cannot come back here (it's not a good time) but I'm continuing to read.
So, Daniele the color of these images can not be obviously real (they are black and white).
Original files are on our Flickr album: https://flic.kr/p/tPP6Cq - https://flic.kr/p/tG8GKv
In the description you will find a "vc" which stands for "virtual color" (we'll try to be more explicit but generally we are always in a hurry!).
They were obtained with the same technique that we used many times for the Rosetta's comet.
Although the colors may match with a good approximation to reality, the main purpose of making a black and white image in color is to emphasize the details. On the other hand, we find that our eye perceives really better in color.

Posted by: wildespace Jun 19 2015, 06:13 AM

QUOTE (eliBonora @ Jun 19 2015, 06:07 AM) *
Hi there, is a bit of time that I cannot come back here (it's not a good time) but I'm continuing to read.
So, Daniele the color of these images can not be obviously real (they are black and white).
Original files are on our Flickr album: https://flic.kr/p/tPP6Cq - https://flic.kr/p/tG8GKv
In the description you will find a "vc" which stands for "virtual color" (we'll try to be more explicit but generally we are always in a hurry!).
They were obtained with the same technique that we used many times for the Rosetta's comet.
Although the colors may match with a good approximation to reality, the main purpose of making a black and white image in color is to emphasize the details. On the other hand, we find that our eye perceives really better in color.


There is a (somewhat false-) global colour map of Ceres, taken at near-infrared, green, and blue wavelengths:



Perhaps you could use that colour information in your images? I'd imagine that the surface's appearance at near-infrared would be similar to what it looks like at red wavlengths.

~~~

Regarding the "mountain", did NASA or any other scientific organisation post an estimate of what it could be?

Posted by: Daniele_bianchino_Italy Jun 19 2015, 08:20 AM

QUOTE
Hi there, is a bit of time that I cannot come back here (it\'s not a good time) but I\'m continuing to read.
So, Daniele..

I have taken from another website
Molte Grazie eli
Thanks ;-)

QUOTE
Although not a volcano, Monte Bianco should be the same size ! smile.gif

yes viking, But Monte Bianco is set in the Alps complex, while volcanoes leave from the sea floor, they make more idea :-)

kilimangiaro:

bromo:

Posted by: Gladstoner Jun 19 2015, 04:46 PM

Spot #5 is nearly on the horizon in today's image:



Posted by: Habukaz Jun 19 2015, 05:42 PM

At first I thought it was some other bright material, but I guess you are right. It's kind of counterintuitive that the bright material inside the crater should be visible from this angle.

Posted by: ZLD Jun 19 2015, 06:15 PM

That does seem pretty strange. Must be peering just over the crater rim.

Posted by: ngunn Jun 19 2015, 07:25 PM

As I mentioned before don't forget that the curvature of Ceres applies as much along the line of sight as it does around the limb. Big craters have convex floors.

Posted by: eliBonora Jun 19 2015, 08:40 PM

QUOTE (wildespace @ Jun 19 2015, 08:13 AM) *
Perhaps you could use that colour information in your images? I'd imagine that the surface's appearance at near-infrared would be similar to what it looks like at red wavlengths.


Yes, I know, it would be possible but maybe be worth waiting for better definitions .. and they are coming! smile.gif

Posted by: scalbers Jun 19 2015, 10:50 PM

Today's image also helps in mapping some of the terrain just south of spot #5.



Full 8K resolution and polar views http://laps.noaa.gov/albers/sos/sos.html#Ceres.

Posted by: eliBonora Jun 20 2015, 05:50 AM

Here a Ceres mosaic (PIA19575 and 19576)

https://flic.kr/p/tX1Qbg

Posted by: antipode Jun 20 2015, 07:04 AM

Now that basin is fascinating, not just for the radial valleys, but for the darker mare-like features on its floor. Someone needs to do some crater counting there when the resolution gets good enough!
Also, whats with that lobate feature to the right of the basin which terminates near those fossae? Almost looks like the basin has overflowed (cryo?)mare materials in the past. Does anyone else see that?

P

Posted by: TheAnt Jun 20 2015, 08:49 AM

QUOTE (antipode @ Jun 20 2015, 09:04 AM) *
Also, whats with that lobate feature to the right of the basin which terminates near those fossae? Almost looks like the basin has overflowed (cryo?)mare materials in the past. Does anyone else see that?


Of course we do see it. smile.gif That part immediately caught my eye also on the image composite that eliBonora provided.
It seem that the crater walls might be slowly filling slowly, if that turn out to be correct they truly would be doing so at a glacial pace.
I cant stop wondering if those larger chunks might be ice or aggregations of the darker surface material that stick together.
In addition there appear to be terrace all round the southern half of the crater that make it seem that the southern region got a higher elevation.

Posted by: alk3997 Jun 20 2015, 03:11 PM

If Ceres still has a glacial fill process that continues today, shouldn't we see some of those small to mid-sized craters partially filled or at least distorted? To me the current surface still looks old. I see Ceres as a body that was one-time active but has now cooled to a point that the surface is no longer active. Any modifications are only done by crater impacts.

Below the surface, we'll have to wait and see what the data says.

Andy

Posted by: TheAnt Jun 20 2015, 05:25 PM

Distorted craters could indeed show us something.
Now that the area right of that large crater show quite less craters than on average, whereas areas north of the crater are literally peppered.
Do this mean that craters have been removed, and only later replaced more recently by a few small craters just at the limit of the image resolution?
And yes, one of the largest ones near the right side of the image actually is distorted.
But we will need higher resolution images before this little hypothesis will fly or be turned over end, most craters in the area are too small to show any detail yet.

Posted by: ZLD Jun 20 2015, 06:36 PM

QUOTE (alk3997 @ Jun 20 2015, 09:11 AM) *
To me the current surface still looks old. I see Ceres as a body that was one-time active but has now cooled to a point that the surface is no longer active.


The surface certainly looks old and battered yes but much younger than a lot of other icy bodies that have been studied. For floating in the asteroid belt, Ceres appears remarkably smooth in a lot of places suggesting some amount of occasional resurfacing in those areas in geologically recent times.

I haven't heard much about the possibility of a http://www.nasa.gov/jpl/herschel/ceres-20140122 around Ceres recently. Has there been any more debate on this? We are unfortunately nearly in the dead of winter on Ceres right now. Has this been laid to rest since that article? There wasn't ever much as far as details on the speculation anyway.

Posted by: ngunn Jun 20 2015, 10:11 PM

QUOTE (ZLD @ Jun 20 2015, 07:36 PM) *
The surface certainly looks old and battered yes but much younger than a lot of other icy bodies that have been studied


Could be just a little bit younger if all the big land-forming action happened early on. The process exposing the white spots on the other hand must be recent and ongoing.

Posted by: Steve5304 Jun 21 2015, 04:07 AM

QUOTE (Gladstoner @ Jun 19 2015, 04:46 PM) *
Spot #5 is nearly on the horizon in today's image:






This image makes ice look plausible...as much as i want it to be somthing like diamonds or aliens.. I am still not convinced the bright spots anomaly was almost entirely blown out of proportion by exposure of the camera.

Posted by: alk3997 Jun 21 2015, 02:09 PM

QUOTE (TheAnt @ Jun 20 2015, 11:25 AM) *
Distorted craters could indeed show us something.
Now that the area right of that large crater show quite less craters than on average, whereas areas north of the crater are literally peppered.
Do this mean that craters have been removed, and only later replaced more recently by a few small craters just at the limit of the image resolution?
And yes, one of the largest ones near the right side of the image actually is distorted.
But we will need higher resolution images before this little hypothesis will fly or be turned over end, most craters in the area are too small to show any detail yet.


Yes, all good questions.

The large craters with the apparently filled-in, but cratered, floors have intrigued me. Perhaps at a large enough kinetic energy an impact breaks through the crust into the subsurface ocean and allows the floors to be filled for a very short period of time. Over time the crust has become thicker and so more kinetic energy is needed to break on through to the other side - the subsurface ocean and allow flows to occur. The deeper the ocean, the shorter the time before the opening freezes again.

This is why only the big craters show signs of resurfacing and yet have middle to small craters within them. Over geologic time it has required more and more impact kinetic energy to cause a flow to occur. The crust near the equator is shallower than near the poles which would explain the differences in large crater density between the equator and the poles.

Andy

Posted by: JohnVV Jun 22 2015, 02:42 AM

QUOTE
Perhaps at a large enough kinetic energy an impact breaks through the crust into the subsurface ocean and allows the floors to be filled for a very short period of time. Over time the crust has become thicker and so more kinetic energy is needed to break on through to the other side - the subsurface ocean and allow flows to occur. The deeper the ocean, the shorter the time before the opening freezes again.

this thing is way too small and there is no "jupiter" to tug at it

it has been a solid bit of ice and rock for a VERY long time
and has been DEEP COLD for a very long time

impacts on "high ice " content are VERY different than on a rock or on nickel /iron

you get very FLAT floors on the impacts in ices

Posted by: dvandorn Jun 22 2015, 04:26 AM

I imagine that impacts onto an ice world (or an icy-rocky-slush world) generate internal heating from acoustic/seismic energy propagating through the body. As we can see, there have been a lot of large impacts on Ceres. so there has been at least localized heating capable of melting ice, at least for a time. I'm not saying that a peppering of impacts could keep the core continuously warm -- I'm just saying that, when it gets really whacked and a big crater or basin is formed, I bet that anything from very localized to larger-area heating occurs. Chaos being what it is, I can imagine pockets of water melting out inside the crust from such large impacts, refreezing, and then getting exhumed by later impact and tectonic forces.

This could mean that Ceres may have been dead, for all intents and purposes, for billions of years, but that a good, solid whack could make it wheeze and burp a bit, even now.

I think when we get a better feel for the compositions of the various texture/albedo/color units, it will tell us a lot more about the possible histories of this curious little world.

-the other Doug

Posted by: Gerald Jun 22 2015, 10:56 AM

Thinking at pockets of water:
The core of Ceres is probably still warm by radioactive decay heat of long-lived isotopes.
"If" the interior is sufficiently warm sufficiently close to the surface, there might have been or still may exist a subsurface ocean.
In this case a large impactor could have penetrated or at least have crushed the maybe 30 km icy surface crust and released some of the liquid of the presumed "mantle" ocean, in some remote analogy to a once suggested origin of the https://en.wikipedia.org/?title=Lunar_mare, besides a melt-up by kinetic impact energy.
Particularly for a large (say a few km diameter) iron-nickel meteorite it shouldn't be too difficult to penetrate the much less dense crust material of Ceres.

Posted by: ZLD Jun 22 2015, 01:45 PM

New images up on Photojournal.

In order left to right: original crop, light decon, darkened w/ decon.



The smallest spots appear to be resolved but also really fuzzy still? Whats up with that?

Strange effect at bottom edge of large spot as well. Sorta looks like CCD bloom but I don't know that I've ever seen a situation where it was so small and also right next to another bloom, without them both merging. And here, we have 4 of them...

Just to throw an idea out there: Impact at a location with near surface water, creating the typical central peak in the crater but with an increase localized heating and pressure in the subsurface water. Water ejects through the peak in a one time eruption, blowing out the side like Mt. St. Helens, scattering salty-icy debris to the right. Sublimation has left the salts behind to slowly decay. Doesn't solve for why we don't see other larger chunks nearby though.

Posted by: alphasam Jun 22 2015, 01:50 PM

Gonna take a stab and say they're looking like mini versions of the big pyramid/mountain thingy.

Posted by: fredk Jun 22 2015, 02:29 PM

What's nice about the new view is that it appears to be a shorter exposure than PIA19568 (but with similar resolution). So in much of the area that was overexposed we can now see detail. Here's a direct comparison with PIA19568:


(All I've done is both frames 2x oversampled and PIA19568 rotated to match PIA19579. Some relative geometrical distortion between the two frames remains.)

The "fuzziness" around the two brightest spots on the right side is clearly real (rather than psf), since much smaller details are resolved elsewhere in the frame. The main bright spot is still overexposed in the centre (at least on the public tifs). It seems to me that we'd need considerably better resolution to understand what's going on here...

Posted by: Gladstoner Jun 22 2015, 04:48 PM

Also today, the big mountain is nicely displayed in profile:



http://photojournal.jpl.nasa.gov/catalog/PIA19578

Posted by: Gladstoner Jun 22 2015, 05:08 PM

In another image released today (I hope 3-image releases are daily from this point forward.... smile.gif ), a handful of fracture bundles can be seen:



1. The main bundle.
2. Bundle that seems to be associated with dark-albedo material.
3. Another bundle.
4. Bundle on basin wall.
5. Faint hint of bundles that connect 1 and 3.

A couple other interesting features:

A. A shallow valley seems to merge with a scarp.
B. Some material seems to 'slop' into a relatively fresh crater.

http://photojournal.jpl.nasa.gov/catalog/PIA19577

Posted by: ZLD Jun 22 2015, 06:41 PM

Can't say with certainty, but it looks like there another long bundle below '4' and above the crater pair, just out of resolution and incidence. Also, there's another at the far right, that would appear to connect to '3' but has been disconnected by an impact, also very faint.

Posted by: alk3997 Jun 22 2015, 06:49 PM

QUOTE (JohnVV @ Jun 21 2015, 08:42 PM) *
this thing is way too small and there is no "jupiter" to tug at it

it has been a solid bit of ice and rock for a VERY long time
and has been DEEP COLD for a very long time

impacts on "high ice " content are VERY different than on a rock or on nickel /iron

you get very FLAT floors on the impacts in ices


Yes, I agree that at those temperatures ice is harder than rock. Ceres surface today looks old to me, so I don't believe there are any active flows going on right now.

However, subsurface there are other factors that *could* be working to make water slush (or water), which could then get exposed by high kinetic energy impacts. As Gerald said long lived radioactive isotopes can provide some heat. While tidal heating isn't possible, the pressures under the crust can provide pockets of heating. Throw in some speculated salts and now the freezing point of the liquid is a little lower. Then add in heat transfer from a high energy object impacting and there could be enough heat for a water flow to occur with a large high velocity impact.

As for how the flow would look, I would expect a wave-like feature that freezes rather quickly. Maybe something like the southern rim of this crater? (Provided by user eliBonora)
https://www.flickr.com/photos/lunexit/18344202083/

All that said, I'm willing to wait for the detailed gravity measurements to see if there is a possibility that Ceres still has anything liquid in its interior.

Andy

Posted by: Gladstoner Jun 22 2015, 06:59 PM

A comparison of craters:



The shape of the main bright spot seems to be similar to the form of the central pit in the other crater. Colored arrows point to possibly similar topographic features. Blue arrows mark high points. Yellow marks breaches in the pit walls. These features (superficially) remind me of the 'capes' and 'bays' of Victoria Crater on Mars.

Posted by: Sherbert Jun 22 2015, 08:49 PM

I would guess the left of the two basins is newer. (Gladstone's previous post.) It has resulted from an impact on the edge of the older basin and is considerably deeper. The crust has been pushed down by the later impact, fracturing the surface and enabling the flow of dust on inclined surfaces.

This is more a conjecture. The left basin has steep terraced sides to the south, but far less well defined rims in its northern half. If the impact was at the edge of the ancient ocean and the totally frozen/rocky Southern polar "continent", the southern crater wall would appear as a normal stepped terrace, the northern crater wall collapsed and less well defined. Also the pressure of the impact would force liquid away from the impact site in the ocean below, allowing the crust to collapse. This collapse would stop at the shore line of the subsurface solid "continent" and indeed such a shore line can be made out and the bowl shape of the collapsed crust made out in an semi circle around the northern crater rim. The centre of the crater appears to be almost dead on the shore line and there is half a central peak, its northern face is missing, either via collapse or sublimation.

It is also particularly clear that North of the shore line the surface is way more smooth and shows very few deep impacts, clear signs of resurfacing and linear scarring indicating expansion/contraction or movement of the surface crust. The darker areas of the poles indicates older less recycled surface. There may not be a dust cycle as dramatic as on 67P, the gravity on Ceres prevents sublimating gases moving dust very far, but where volatile ices are near to the surface, dust will move and resurface the comet. I would suggest this is happening on a very small scale now, but in the past when the crust was thinner and in areas where the crust has been thinned or penetrated by impacts, the movement of dust by sublimating gases would have been significant enough to resurface the comet on a local level. It could be that at a low level this is what is keeping some areas of exposed ice/salt exposed, the subsurface sublimating gases escaping at the surface preventing dust settling to recover the exposed areas. Once all the volatiles are exhausted the surface becomes covered in dust. If the volatiles are being replaced by more from below, say in a very deep crater or fissure, the dust could be held at bay for a significant length of time.

Following on from that, how many of the craters on Ceres are impact craters and how many sublimation derived features such as those on 67P? An explosion of pressurised, sublimated gases within the crust could leave craters similar to Spot 1 for instance, the ejecta being the unexposed ice of the crust dispersed by the explosion. It might prove interesting to compare the craters with those left by underground atomic bomb tests. The suggestion of Spot 5 being a central mountain that blew off one of its sides, like Mt St. Helens, seems another example. Ceres is dark and absorbs a lot of sunlight, that heat must travel into the crust and have consequences, such as creating pockets of sublimated gas. Even if an impact does not penetrate to the liquid below it exposes these pockets and increases the possibility of the pressure within resulting in the explosive creation of features on the surface. The strange mountain could be another example, a small high energy impact penetrating a large "magma" chamber of volatile gases, perhaps added to by fluid under pressure escaping from the ocean below.

The coming week's pictures may suggest a whole different scenario, so this is just little more than a thought experiment to ferment ideas. We are dealing with a surface crust made largely of Water Ice, most especially, I would suggest, in the equatorial and mid latitudes. The ocean may well not ever have developed in polar regions and the surface there maybe largely made of refractory materials, rock and organics. The shrivelled and shrunken appearance of the surface we see today suggests to me that there are no longer large volumes of Water blow the crust, if any, but there may still be lakes and small seas where the energy of past impacts has locally delayed the slow freeze.

Posted by: Habukaz Jun 22 2015, 09:58 PM

The fuzziness of the of the bright spots to the right makes me think of cryovolcanic vents spewing out a thin spray of water.



Though I guess them being miniature versions of e.g. the bright crater we saw earlier is still a good explanation.

Posted by: dvandorn Jun 23 2015, 12:27 AM

If you're right, Habukaz, then this makes two different sets of features that resemble cryovolcanic versions of fire fountains. At region 5, here, very bright effluent has been emplaced, while in other areas, near the scratch-like wrinkle features, dark material seems to have been emplaced.

I wonder if the same processes are generating both types of features, the difference being the specific type of "lava" being generated. I know that, on the Moon, differences in the lavas feeding the various fire fountains generated glasses ranging in color from green to red to black -- could different cryo-lava constituents determine whether you get a high-albedo unit emplaced vs. a low-albedo unit?

-the other Doug

Posted by: alk3997 Jun 23 2015, 02:35 AM

But, what about the side view image that Gladstoner uplinked on page 2?

http://www.unmannedspaceflight.com/index.php?act=attach&type=post&id=36162

Shouldn't we see something resembling relief, if not a fountain, in this image?

I'm not saying I understand the bright spots, but I still have doubts over an active vent/cryovolcanism.

Andy

Posted by: dvandorn Jun 23 2015, 03:27 AM

Ooops, sorry. I see that I mis-spoke a bit. I didn't mean to say we were seeing active fountains, I meant we may be seeing the results of fountain-like activity in the past having emplaced very high-albedo material at S5, and very low albedo material in other places, like the "scratches" type formation that has been noted to be surrounded by dark terrain.

I was referring to the end effect of such fountain activity, not trying to say it's happening right now. Sort of hard to say how long ago something like that might have happened, though. It will help enormously when we start getting some compositional clues.

-the other Doug

Posted by: alk3997 Jun 23 2015, 03:33 AM

QUOTE (dvandorn @ Jun 22 2015, 10:27 PM) *
Ooops, sorry. I see that I mis-spoke a bit. I didn't mean to say we were seeing active fountains, I meant we may be seeing the results of fountain-like activity in the past having emplaced very high-albedo material at S5, and very low albedo material in other places, like the "scratches" type formation that has been noted to be surrounded by dark terrain.

I was referring to the end effect of such fountain activity, not trying to say it's happening right now. Sort of hard to say how long ago something like that might have happened, though. It will help enormously when we start getting some compositional clues.

-the other Doug


I misunderstood - sorry about that.

I won't be surprised if this turns out to be the result of some type of past cryovolcanic activity. The one thing I'm having problems with is figuring out how anything that is this relatively bright remains this relatively bright while being subjected to eons of solar radiation (and other types of particle radiation). I just can't get past that yet.

Andy

Posted by: Habukaz Jun 23 2015, 08:33 AM

I was also thinking about the coating produced by such activity. I do think it could still be active though - any spray of water could be so tenuous that Dawn's cameras would not be able to detect it under even the best of conditions. If such a spray was thick enough to be easily seen, I guess the results (ice coating) would be a lot more dramatic than the bright spots we see.

Posted by: ZLD Jun 23 2015, 01:39 PM

If active, what about some type of water slurry cryomagma? This would flow out like lava here on Earth, down the sides of whatever formation is there, or build up into a dome if thats the case. As it cools, it would probably frost over leaving a fuzzy looking, semi-transparent film, depending on non-water particle content. Still looking through research papers on the topic but the topic of what happens after the cryomagma is out in the open, is less interesting to discuss.

Posted by: nprev Jun 23 2015, 02:40 PM

Re the possibility of active plumes: As I recall, there was at least one terrestrial spectroscopic observation of a water vapor transient a few years back & the estimated total quantity of material was quite small, perhaps a few hundred kilograms. Presumably a surface feature erupting continuously enough to appear blurred in Dawn imagery would produce a far larger amount of water vapor over time with a correspondingly larger spectroscopic signature.

I don't know if similar observations are underway right now, but given the above it seems unlikely that we're seeing an active eruption here.

Posted by: ZLD Jun 23 2015, 04:06 PM

Spectroscopy isn't really my area. What are the prospects of detecting a non-plume like eruption? Say, if it is coming out very slowly as an extremely viscous, ammoniated or sulphated mud.

Full disclosure: I agree that it is extremely unlikely for any activity.

Posted by: Doug M. Jun 23 2015, 04:52 PM

Something I haven't seen discussed yet: are we seeing any evidence of volatile transport? Ceres regularly warms up to over 200 K in middle and lower latitudes, and at those temperatures water and carbon dioxide ices will have significant vapor pressure. Most volatiles at or near the surface would quickly sublimate and be lost to space, but some might accrete in cold traps -- and there might be ice not far below the surface.

So, first, is there any indication yet of subsidence or other effects that might be attributed to the sublimation of subsurface volatiles over geologic time?

And second, is there any sign yet of ice in cold traps? (We didn't find any on Vesta, but Vesta has a large axial tilt -- 27 degrees -- while Ceres has hardly any. And if surface ice can survive on the Moon and Mercury...)


Doug M.

Posted by: nprev Jun 23 2015, 06:08 PM

ZLD, I think that the answer is the same. Any semi-liquid substance viscous at Ceres' surface temperature will have a vapor pressure, and since there's no atmosphere there should be a substantial amount of diffusion. Even lava would have volatile fractions (as you mentioned) like sulfur. Ceres is known to be water-rich, though.

Bottom line is that I think we're still seeing the effects of CCD saturation by high-albedo surface solids, not gas or vapor. Whatever that stuff is (and my bet is ice) it's WAY reflective. Gonna require even higher-resolution views to make sense of it.

Posted by: TheAnt Jun 23 2015, 06:23 PM

QUOTE (Doug M. @ Jun 23 2015, 06:52 PM) *
Something I haven't seen discussed yet: are we seeing any evidence of volatile transport? Ceres regularly warms up to over 200 K in middle and lower latitudes, and at those temperatures water and carbon dioxide ices will have significant vapor pressure. Most volatiles at or near the surface would quickly sublimate and be lost to space, but some might accrete in cold traps -- and there might be ice not far below the surface.


Interesting question Doug, I did indeed expect a bit of sublimation, and that such might be the source of the tentative reports of water molecules and/or hydroxyl.
This could have let frost accumulate closer to the poles, in partially shadowed craters or other suitable locations.
But even in the early images we could not see anything such, and that most of Ceres comes with a very dark surface, with only dots of very bright material in very few locations. This surface material might have water incorporated just as have been found on Luna, but that it is buried a bit under the surface also keep it buried and shaded so very little ever evaporate. And that's why I now find that crystals of salts is a strong contender candidate for the bright areas we see, with the possible exception of area 5, which may be ice.

Posted by: pioneer Jun 23 2015, 06:55 PM

I understand Dawn has a Gamma Ray and Neutron Detector and a Visible and Infrared Mapping Spectrometer to determine chemical composition. What have they told us about the bright spots on Ceres?

Posted by: Paolo Jun 23 2015, 07:09 PM

QUOTE (pioneer @ Jun 23 2015, 07:55 PM) *
I understand Dawn has a Gamma Ray and Neutron Detector


these two are probably not getting any meaningful signal from the surface in the present high orbit

Posted by: Sherbert Jun 23 2015, 07:26 PM

I also think sublimation of volatiles may be involved in shaping the surface. I have been trying to explain why the bright spots all over Ceres are not covered in Ceres regolith. Either the precesses creating the bright material are very recent, or even current, or some mechanism is slowing down the recovering process.

If we assume the bright material is Water Ice or frozen brine, sublimation rates would be high, creating a significant "breeze" very close to the surface, which could be sufficient to disturb and remove dust. So if volatiles are ejected onto the surface it may take a considerable length of time for them to be recovered in dust. This image, highly upscaled and zoomed, is of the bright spots in "Spot 5".

https://www.flickr.com/photos/124013840@N06/18471295953/in/dateposted-public/

My interpretation is the largest bright area, on the left, is a sort of Ice "lava" lake sitting inside a Caldera, possibly still being refreshed from below, though highly unlikely. However, the amount of sublimated gas from such a volume of Ice, could keep the area dust free. On the right flank of this Caldera it can be seen that the mound is constructed in layers and lighter, but not bright, "lava" flows can be seen radiating from the central Caldera. Smaller eruptive sites nearby could also create the smaller blotches, they also have slightly lighter "lava" flows radiating from them. They could also be depressions or small craters filled up with fluid ejecta from the larger Cryovolcanos or "Hot Springs", "Geysers" and mud Cryovolcanos. The farthest right appears to have built a sizeable cone too. Once again the resolution is not quite good enough to be sure and a small degree of interpretive license is required. It looks to me that this is, or was, a Cryovolcanically active region. The deep crater it is situated in, suggests the thickness of the Ice crust is very thin in the bottom of the crater and the original impact may have opened a crack in the crust either temporarily or possibly it is still there. Others have traced a fault line running through the crater that appears to run up the right side of the large Caldera, although it could be interpreted as a channel carved by "hot" liquid erupting from the Cryovolcano, it has a "river" like appearance.


Posted by: Phil Stooke Jun 23 2015, 07:27 PM

Paolo's right, GRAND gets pretty much nothing until the very lowest orbit. VIMS can get dood data now, but nothing has been announced yet.

Phil


Posted by: fredk Jun 23 2015, 07:39 PM

Apart from this release based on observations in February:
http://photojournal.jpl.nasa.gov/catalog/PIA19316

Posted by: Sherbert Jun 23 2015, 07:47 PM

This is interesting. Is this erosion or sedimentary layering?

https://www.flickr.com/photos/124013840@N06/18907526639/in/dateposted-public/

This is close up from this original.

http://www.nasa.gov/sites/default/files/thumbnails/image/pia19574-1041.jpg

Posted by: eliBonora Jun 23 2015, 07:52 PM

An anagliph of Spot5's crater (from PIA19579 and 568)

https://flic.kr/p/uLXpd5

Posted by: Gladstoner Jun 23 2015, 07:55 PM

QUOTE (Sherbert @ Jun 23 2015, 02:47 PM) *
This is interesting. Is this erosion or sedimentary layering?


It is likely a set of fractures. Crater rim slumping comes to mind, but they don't quite line up 'right'.

Posted by: Sherbert Jun 23 2015, 08:02 PM

[quote name='eliBonora' date='Jun 23 2015, 08:52 PM' post='221699']
An anagliph of Spot5's crater (from PIA19579 and 568)

Looking at that, the whole crater could be a Caldera.

Posted by: Sherbert Jun 23 2015, 08:06 PM

QUOTE (Gladstoner @ Jun 23 2015, 08:55 PM) *
It is likely a set of fractures. Crater rim slumping comes to mind, but they don't quite line up 'right'.


Agreed. Also interesting are some of the hollows in the crater wall, they look similar to formations on 67P, though they could still be the result of impacts. Evidence of multiple resurfacing events maybe?

Posted by: scalbers Jun 23 2015, 08:11 PM

We have discussed this to be a rim section of a larger basin. Is there a secondary process going on in the crater wall?

Posted by: Gladstoner Jun 23 2015, 10:24 PM

QUOTE (scalbers @ Jun 23 2015, 02:11 PM) *
Is there a secondary process going on in the crater wall?


Probably. They appear to have formed well after the large impact but before the wall slump. The orientation of the fractures probably indicates stresses not directly related to the basin structure.

Posted by: Sherbert Jun 23 2015, 10:54 PM

This is the same rim wall from a different angle. I still can't decide the cause, fracturing seems plausible, a slightly fortuitous wall slump process or layers made by resurfacing processes prior to the impact that created the basin. In this image the layering can be seen to the right of the steep rim/cliff, which probably rules out cliff slumping. I have added some arrows to point out the 67P like formations and from this view, the layering looks similar to that seen on 67P too. In that light it may just be down to differential erosion due to sublimation of volatiles in the exposed crust. Whatever the cause, its strange it is only seen in this one section of the cliff.

https://www.flickr.com/photos/124013840@N06/19098022865/in/dateposted-public/

EDIT: If that area of bright material is associated with a Cryovolcanic source, maybe its past "lava" flows?

Posted by: Gladstoner Jun 23 2015, 11:27 PM

I'm leaning toward it a series of vertical or high-angle fractures mainly because there are a couple similar features nearby on the basin floors.

Also, at this point, I think layering is less likely also because it is the only example observed (so far) in a crater or basin wall. That is, unless the slump just happens to expose a rare example of a section of 'lava' flows or whatever. But then Ceres is already known for its 'unlikely' and isolated features (bright spots, the big mountain). smile.gif And finally, who knows what will turn up in relatively fresh rim scarps once higher resolution imagery comes in.

Posted by: Wocket Jun 24 2015, 12:37 AM

Newby here. I can construct a hypothesis for the bright spots by taking pieces of the various ideas posted in this thread. 1) Ceres has salts on or very near the surface, which are left over from a time when it was warmer and spewing water/salt mixtures over the surface. 2) Over time, the salts darken upon exposure to radiation. 3) There are occasional impacts into the surface which cause localized heating. If I couple these with the observation that radiation-darkened salt can be bleached back to white upon exposure to heat, then that might explain the distribution of these bright spots. Explicitly, occasional impacts warm the surface, bleaching the ice back to its brighter, higher albedo form until it darkens back over time. The salt deposits would have been preferentially deposited in the lower areas like crater basins, but would otherwise appear sort of randomized, due to the random impacts coming in.

Here is a somewhat relevant reference: http://www.sciencedirect.com/science/article/pii/0019103579901702#

I also read a bit that sunlight can bleach some salts back to being bright, but could it be that Ceres is too cold or far from the sun for that to dominate the radiation induced darkening?

Anyway, that's my utterly amateur guess.

Posted by: monty python Jun 24 2015, 05:15 AM

Yes. I just can't get my head around how we could be seeing a freshish ice deposit on such an old and probably dead world, so salt it is.

And just to think outside the box, is the bright stuff from an impactor?

Posted by: nprev Jun 24 2015, 05:49 AM

QUOTE (monty python @ Jun 23 2015, 09:15 PM) *
And just to think outside the box, is the bright stuff from an impactor?


Could well be, or exhumed fresh ice from recent impacts. The only way original impactor material could survive in such relatively pristine (and closely grouped) condition would be via a VERY low impact velocity. That would be a more tenable hypothesis if there was just one such feature on Ceres, but there appear to be several.

Posted by: alk3997 Jun 24 2015, 03:39 PM

QUOTE (nprev @ Jun 23 2015, 11:49 PM) *
Could well be, or exhumed fresh ice from recent impacts. The only way original impactor material could survive in such relatively pristine (and closely grouped) condition would be via a VERY low impact velocity. That would be a more tenable hypothesis if there was just one such feature on Ceres, but there appear to be several.


We had discussed the low energy/velocity impactor theory back in one of the earlier threads and I'm certainly still in that "camp", with maybe the impactor actually being a rubble pile. I don't like to use a theory that requires a currently active body when there are still alternatives that fit the available data.

One possibility to explain the multiple locations is that there are rubble piles near Ceres orbit that were originally pieces of Ceres until they were excavated by an impact. These almost co-orbitals eventually find there way back to Ceres at a very slow velocity with little mass.

Andy

Posted by: rogelio Jun 24 2015, 04:50 PM

"....low energy/velocity impactor theory... with maybe the impactor actually being a rubble pile..."

...If that's the case, why didn't we any white spots on, say, Vesta?

Posted by: alk3997 Jun 24 2015, 04:58 PM

QUOTE (rogelio @ Jun 24 2015, 11:50 AM) *
"....low energy/velocity impactor theory... with maybe the impactor actually being a rubble pile..."

...If that's the case, why didn't we any white spots on, say, Vesta?


Very different orbit.

http://nssdc.gsfc.nasa.gov/planetary/factsheet/asteroidfact.html

Posted by: JRehling Jun 24 2015, 05:26 PM

Some qualitative thinking where computational modeling would be required, but:

If Ceres had a significant subsurface H2O aquifer at some point in the past when it was relatively warmer, and then cooled, then the expanding ice had to go somewhere. Globally, this would cause extension if the stress were applied equally everywhere, but violent venting seems like another apt outcome. There would be subsurface water with ice atop it, the ice layer thickening but subject to the weight of the crust above it. Where it vented, there could be tremendous lateral flow to draw from the water layer worldwide, continuing the eruption for quite some time. The water blasting out at the surface would probably undergo a lot of evaporation and loss into space, although perhaps it could have caused a significant temporary atmosphere. What didn't escape could have caused monumentally large accumulations of ice on the surface.

Maybe what we're seeing is the result of a relatively small number of such eruptions, which eventually let out all of the excess pressure caused by the expansion of freezing H2O.

Posted by: FOV Jun 24 2015, 05:28 PM

Polar region crater with more of the light coloured material:


Posted by: Gladstoner Jun 24 2015, 05:49 PM

QUOTE (ZLD @ Jun 20 2015, 12:36 PM) *
.... I haven't heard much about the possibility of a http://www.nasa.gov/jpl/herschel/ceres-20140122 around Ceres recently. Has there been any more debate on this?


QUOTE (JRehling @ Jun 24 2015, 11:26 AM) *
.... The water blasting out at the surface would probably undergo a lot of evaporation and loss into space, although perhaps it could have caused a significant temporary atmosphere. ....


With darkish, plume-like features like the ones extending from spot #5:



I can't help but think about the possibility of a temporary atmosphere.

Posted by: Gladstoner Jun 24 2015, 05:58 PM

QUOTE (FOV @ Jun 24 2015, 11:28 AM) *
Polar region crater with more of the light coloured material:


That feature does look similar to this:



Both may be where impacts exposed subsurface intrusions of the white stuff.

Posted by: Habukaz Jun 24 2015, 06:17 PM

The lower half of that bright crater has a really strange appearance. Looks like something has modified it (like a later impact or two).

Posted by: ZLD Jun 24 2015, 08:18 PM

It gets even stranger looking if you flip it upside down.




I almost think an impact actually pushed the soil upward and out into a sort of hanging cliff?

Also, another oddity crater from SOrb12




Zero clue here. I got nothing.

Posted by: JRehling Jun 24 2015, 08:26 PM

QUOTE (Gladstoner @ Jun 24 2015, 10:58 AM) *
Both may be where impacts exposed subsurface intrusions of the white stuff.


I'm looking at photos of Ganymede, which has a lot of rayed craters that exposed bright, subsurface ice. The phenomenon on Ceres is definitely something different. Related, perhaps, but every example on Ganymede has common characteristics that none of the examples on Ceres match.

If this is a mere "ray" event (also visible on the Moon, Mercury, etc.), then there's something very different on Ceres about how the material is surfaced or how it ages.

I'd guess we're either seeing the remnants of a ray system that sputters away quite differently than the rays on Ganymede, et al, do, or these are eruptions.

If it were simply subsurface salt, I'd expect them to look like Ganymede/Moon rays and to be less selective in their occurrence.

Perhaps icy ray material on Ceres is coarse near the point of origin and sparse far from it and therefore sputters away rapidly except where it's most coarse. Eg, a 20 kg lump of ice may stick around much, much longer than lots of microgram particles.

Alternately, I'd stick with the idea of eruptions: Which may be triggered when the impact occurs, or possibly much later.

Posted by: centsworth_II Jun 24 2015, 09:00 PM

QUOTE (ZLD @ Jun 24 2015, 03:18 PM) *


I almost think an impact actually pushed the soil upward and out into a sort of hanging cliff?

The white rays spray out in the opposite direction of the dirt pile. It doesn't look like both could be the result of "impact push".

Maybe an impactor hit a sub-surface bed of salty ice. The white spray is the salt left from icy ejecta. The impact melted the sub surface ice leading to a sinkhole-like slump on the side of the crater opposite the white rays.

I'll try to resist any further amateur speculations. laugh.gif

Posted by: ngunn Jun 24 2015, 09:06 PM

QUOTE (JRehling @ Jun 24 2015, 09:26 PM) *
a 20 kg lump of ice may stick around much, much longer than lots of microgram particles


Do you mean long on a geological timescale? Do you have a very rough estimate for the length of time a 20kg lump would last?

Posted by: Gladstoner Jun 24 2015, 09:10 PM

QUOTE (JRehling @ Jun 24 2015, 03:26 PM) *
If it were simply subsurface salt, I'd expect them to look like Ganymede/Moon rays and to be less selective in their occurrence.

This is why I suspect much of the white stuff is in the form of intrusions (veins, dikes, 'volcanic necks', etc.) in places deep beneath the surface.

A terrestrial comparison I have in mind is pegmatite, which is the solid end point of granitic magma crystallization. On Ceres, the 'granite' would be water ice, and the 'pegmatite' would be the leftover material that could not be incorporated into the ice crystals. This 'pegmatitic magma', which would be a concentrated brine containing various salt and volatiles (CO2, NH3, etc.) would either dry or freeze out in place or eventually make it to the surface as an extrusion of some kind. The entrained gases would help to drive the eruption as they do on Earth.

Spot #5 could be the best -- or only -- example where this brine breached the surface due to eruption rather than by exposure due to impact or mass wasting.

Edit 1: In many spots, this material may merely permeate existing fractures within the megabreccia (think of mineral veins on Mars). In these cases, the intrusions may resemble petroleum reserves more than they do magmatic plutons.

Edit 2: And speaking of crater rays, I would not expect exposed water ice to remain for long after an impact excavated and dispersed it like this (assuming all white material is the same stuff):


Posted by: JRehling Jun 24 2015, 09:42 PM

I see a citation from Lanzerotti, et al, 1978 to the effect that:

Solar wind erosion for pure water ice is about 10 angstroms per year at 1 AU and falls off with the inverse square of the distance. So, at Ceres, about 3 angstroms per year.

At that rate, a 10 cm ice layer would vanish entirely in about 300 million years. That's longer than the age of Tycho on the Moon, and about as old as Aristarchus.

So, chunks about 30 cm across would survive near younger craters, but not near older ones, and snowflakes would disappear almost instantly in geological terms.

Posted by: scalbers Jun 24 2015, 09:59 PM

Would the ice sublimation rate be greater than the solar wind erosion rate at the ambient temperatures? The moon provides some guidance:

http://people.nwra.com/resumes/andreas/publications/Icarus_Moon.pdf

Posted by: Gladstoner Jun 24 2015, 10:05 PM

QUOTE (JRehling @ Jun 24 2015, 03:42 PM) *
I see a citation from Lanzerotti, et al, 1978 to the effect that:
........
So, chunks about 30 cm across would survive near younger craters, but not near older ones, and snowflakes would disappear almost instantly in geological terms.


If the stuff indeed is ice, then 1) pure ice would still be in the form of scattered or isolated intrusions (since it is sporadic in occurrence), and 2) constraints could be made on the form that the ice takes on the surface, e.g. larger particles would be more likely to remain than smaller grains or frost.

Posted by: bsharp Jun 24 2015, 10:15 PM

From today's PIA19581, upper right. It almost looks like a mudslide from the impact on the rim



There are also a couple of nice central peak shadows at the upper terminator in the TIFF.

Posted by: antipode Jun 24 2015, 11:05 PM

Looks like a landslide caused by the impact of that fresher crater on the rim of the larger one.
But, aren't there some tiny exposures of bright material on the rim of the fresher crater? ohmy.gif

P

Posted by: Sherbert Jun 25 2015, 12:57 AM

I am wondering how relevant the paper released today by the OSIRIS team working on 67P is. They talk about ices being exposed by sublimating gases removing the surface crust to reveal the rock hard, sintered ices below. Lab experiments show, even in Earth's gravity, the vapour pressure is sufficient to remove surface layers in centimetre sized flakes. Incidentally there are some figures on how long Water ice takes to sublimate in this region of the solar system, very roughly 1mm per hour, so even large chunks of uncontaminated ice are not going to last more than days or weeks if exposed to sunlight. Ice contaminated with darker dust or organics will absorb more energy, so would disappear even quicker.

So far we don't seem to have much information on what the surface regolith is made up of. How much is silicate type dust or inorganic salts and how much organics, Tholins for example, and how thick it might be. Probably have to wait for the lower orbit to get the required spectroscopic data. The visual evidence is for a pretty mobile "dust" layer in the past, judging by the way so many craters have been partially obliterated or filled in. I suspect in the past the surface "dust" layer was way thinner and as a result a lot more mobile than now due to sublimating ices creating a mini atmosphere close to the surface as others are suggesting. Sublimation residue and organics build up mean the "dust" gets deeper, its insulating effect increases, reducing the amount of heat reaching subsurface ice and hence the amount of gas escaping at the surface.

Impacts, cliff falls, sublimation erosion, Cryovolcanic activity, ice expansion fractures and elevation changes, all adds up to multiple possibilities for subsurface ice re-exposure. Its probably possible to find examples of all of them. Once revealed the sublimating surface ice would tend to keep itself free of "dust" for long periods of time, only starting to darken as non volatile organics produced by UV radiation slowly build up and start to insulate the ice again. It seems only a millimetre or two of insulating "dust" is sufficient to completely prevent the ice being seen visually or spectroscopically, hence the paucity of bright material.

The visibility and longevity of any surface ice depends on how much contamination there is in the ice, its chemical composition and the distribution of that contamination. Sublimation residue could well be the major component of the surface "dust" layer, as on 67P, in which case the surface would reflect the distribution of contaminants trapped in the frozen ice. It might be that the really bright material of Spot 5 is ice formed directly from "cleaner" liquid water below. The "colourised" map the team released shows the surface composition is varied. As I understand it, the science team think due to convection processes within the ice layer, this variation is a reflection of the rock core interaction with the proposed ocean, past or present, beneath the icy crust.

Posted by: TheAnt Jun 25 2015, 03:26 AM

QUOTE (ZLD @ Jun 24 2015, 10:18 PM) *
It gets even stranger looking if you flip it upside down.




Also, another oddity crater from SOrb12




Zero clue here. I got nothing.


I wonder if the first one is an impact crater at all.
It might have started as one yes, but distorted by some runaway erosion after exposing ice. and centsworth_II might be on the mark with that "sinkhole-like" suggestion.
There's a larger and wedge like feature at the bottom of that image that might be one older formation of the same kind.

The second image certainly got a flow, and bsharp pointed out another of the kind. You know me by now and that I like glacial features, but showing some caution for once, can we rule out dust and other surface material could cause anything such?

Posted by: ZLD Jun 25 2015, 03:39 AM

I like the glacial idea and I've seen some other fairly convincing areas that may show evidence. However, with this one, from this single angle we have, the edge that would appear to be flowing into the crater, goes up to a rim that is also above the surface just beyond the crater. So unless there was a one time, a much larger glacial mass that eventually deposited here and has since sublimated away (or something), it doesn't make sense to me.

Also just noticed some interesting lines to the lower left of the same crater as well.

Posted by: TheAnt Jun 25 2015, 04:20 PM

QUOTE (ZLD @ Jun 25 2015, 05:39 AM) *
I like the glacial idea and I've seen some other fairly convincing areas that may show evidence. However, with this one, from this single angle we have, the edge that would appear to be flowing into the crater, goes up to a rim that is also above the surface just beyond the crater.....


Oh dear, that's one detail I missed, yet all happy I did advice some caution for my interpretation then. =)

And yes, several here have noted features that look quite like glacial features that apparently flow covered by the dark surface material.
We might have to wait for the lower orbit before Dawns instruments give us some insight, and yes I did not spit it out in my previous post, I am suspicious about bsharp's 'mudslide' it might be some other material there. Perhaps one avalanche of dust and fine sand.

Posted by: FOV Jun 25 2015, 04:59 PM

If that crater from yesterday's release isn't a pure crater, and as ZLD suggested a hanging cliff on part of the rim, well when I googled such a feature a terrestrial example of an overhanging cliff made out of basalt was what I got.

OTOH all the uneven, bumpy looking material (frozen old slush?) on some crater floors and slopping over crater rims, gives me the impression of an icy mix of some sort.

Here are a couple (enlarged and cropped) from the latest release:





That cliff feature could be made of icy material too?



Posted by: Gladstoner Jun 25 2015, 05:07 PM

Re: this crater discussed above:



This other crater near the lesser southern basin also is strangely filled with some material:




In this case, though, it appears to have been part of a wider resurfacing process.

Posted by: Mr Valiant Jun 25 2015, 05:08 PM

Ceres may well be the lab that will help explain the behaviour of water/ice in a hard vacuum.

Posted by: Steve5304 Jun 25 2015, 06:35 PM

QUOTE




Pac Man ! blink.gif laugh.gif

Posted by: Habukaz Jun 25 2015, 07:51 PM

Pac-Man is ubiquitous in the solar system.

Posted by: John Broughton Jun 25 2015, 11:14 PM

The mound left of centre in this crater could be the source of some of the potentially erupted material. Is that a pit I see at its summit?


Posted by: ZLD Jun 26 2015, 02:05 PM

Here's a morph between SO13 and SO14 of the strange cliff sided crater.

http://i.imgur.com/wW0fJ5r.gif
(click to animate)

Can't say this helps it make more sense but gives a better idea of the topography going on here.

It could just be an artifact of the morph (especially since there is a big one at the bottom) [edit: fixed] but the crater on the left maybe seems to be on a mound. If you look at the raw images, especially SO13, it does seem to cast a slight shadow upward suggesting it protrudes from the ground. Maybe the channel in front of it is similar to the deep channel that has been noted next to the large suspected volcano? The mound crater on the left also seems to have what looks like a dried flow of the white material on the right side and it appears as if it could be coming from a section of the rim that has fallen.

Just another observation, and isn't really that relevant probably but the cliff sided crater reminds me a bit of some of the smaller calderas on Io. In this case, maybe this was not a crater at all and it was some type of ground level volcano that filled up and maybe something kind of like a nested summit. The raying around the edges don't seem typical of most impacts. They appear to maybe be more a result of something sputtering the material outward.

----------
Edit 0.5 (late Friday night, kids alseep, whew)
----------

Almost forgot I made a flyover of this region.


It appears that the nearby crater does sit on a mound of sorts. One forms the large caldera while a vent spews out enough to form a cinder cone?

I'll try to get a flyover of Spot 1 made tomorrow. I used to think it was probably the lesser interesting spots but it could be one of the largest caldera in the solar system!

----------
Edit
----------

Looking at SO14, i see a lot of craters that have infilling. I think the central object may be a caldera of sorts as well.



Just need some indication that it sits higher than all of these other points.

Posted by: ZLD Jun 26 2015, 05:05 PM

Here's another morph. SO5 -> SO14, Spot 1, large sputtered crater.

http://i.imgur.com/eEvulOS.gif

I went through this fairly meticulously to minimize artifacting and ensure accurate movement. There's still a few elements that snap into place. I may have a chance to fix those later. [edit: fixed, mostly]

I really would like to throw this in as another likely cryovolcano. From this, it appears to be uplifted from the mean level of the surface, the crater walls appear strikingly vertical in comparison to other impacts all over the surface and as I previously posted, it appears to have a high number of infilled craters surrounding it, suggesting something was around to pour... whatever, into them. And if this is the case, I think it is also highly likely that most other similarly bright sputtered areas share this volcanic activity in common.

Posted by: scalbers Jun 26 2015, 08:10 PM

The SO13 and SO14 images are just what I was waiting for to do a map update.



Full 8K resolution and polar views http://laps.noaa.gov/albers/sos/sos.html#Ceres.

Posted by: ZLD Jun 26 2015, 10:30 PM

And one final morph today. Spot 5 from SO3 to SO 11.

Unfortunately, its entirely unimpressive! Here it is anyway.

http://i.imgur.com/AqVFAcZ.gif

Just to add some more speculation here, I think a possible remnant of a similar event was seen during OpNav9 in file PIA19563. Similar cracking of the surface can be seen around Spot 5. I think this was discussed before.


Posted by: Gladstoner Jun 27 2015, 02:13 AM

QUOTE (ZLD @ Jun 26 2015, 04:30 PM) *
Unfortunately, its entirely unimpressive!


Not entirely unimpressive. It helps to illustrate the albedo gradations.

Posted by: Zelenyikot Jun 27 2015, 07:58 AM

My try to make anaglyph of the white spots.


 

Posted by: Cotinis Jun 27 2015, 02:13 PM

QUOTE (Jaro_in_Montreal @ Jun 17 2015, 05:28 PM) *
A different view of that pingo/volcano/whatever and more white stuff.....



Newbie here. To me, the form of the mountain looks more like a pingo than a volcano. The two steep-walled craters (or pits) nearby look suspicious--wonder if they could be collapsed remnants of similar mountains--after the icy cores sublimated away. What an amazing landscape, full of surprises!
--Cotiinis (Patrick) in NC (Edited to show image thumbnail of that area.)

Posted by: Steve5304 Jun 27 2015, 02:45 PM

I dont think its a volcano. Looks like a mudball hitting a frozen concrete wall. I can almost hear the 'thwap'...add a few years of time and it gets covered in dust. Just my opinion. I would think ceres is just to small and any volcanos early on during formation would of smoothed away by bombardment but who knows this tiny rock is full of suprises.


Spot 5 has me wondering i watched a short on nasa youtube channel about what it maybe. One of the ideas thrown out is active water geysers mixed with some compound...does anybody know if dawn is equipped to solve the mysteries of the white spots?

Posted by: dudley Jun 27 2015, 04:48 PM

QUOTE (Zelenyikot @ Jun 27 2015, 08:58 AM) *
My try to make anaglyph of the white spots.

The anaglyph looks very good, Zelenyikot. The high elevation of the crater rim is very distinct. The bright spots appear quite flat against the floor of the crater. This recalls to mind the observation by one of the mission scientists, that the bright spots must be elevated well above the floor of the crater, since they continue to appear lighted when the floor of the crater is dark. If, as it now appears, this isn't so, some other explanation for the continued lighting of the bright spots will presumably be needed.
As a side note, I observe that the bright spots are all notably brighter in the blue channel than in the red. Perhaps there is a technical explanation for this. If not, maybe the light from the bright spots is actually stronger in the blue part of the visible spectrum than in the red.

Posted by: fredk Jun 27 2015, 05:30 PM

The left and right channels are only coloured red and blue for the anaglyph. They're both greyscale images originally. One looks like a longer exposure than the other, as I illustrated in http://www.unmannedspaceflight.com/index.php?s=&showtopic=8037&view=findpost&p=221630

Posted by: TheAnt Jun 27 2015, 11:13 PM

QUOTE (Cotinis @ Jun 27 2015, 04:13 PM) *

To me, the form of the mountain looks more like a pingo than a volcano.


Could be, a pingo is created by liquid water beneath, and those are quite smaller in size though Ceres weaker gravity might have helped.

As for the connection between craters and flows this feature on Mars might provide a suitable comparison.


Posted by: jgoldader Jun 28 2015, 12:54 AM

QUOTE (Steve5304 @ Jun 27 2015, 09:45 AM) *
Spot 5 has me wondering i watched a short on nasa youtube channel about what it maybe. One of the ideas thrown out is active water geysers mixed with some compound...does anybody know if dawn is equipped to solve the mysteries of the white spots?


Dawn does carry a mapping spectrometer. Spot 5 really stands out in visible light, but IIRC it was not prominent in the IR in an image released on the way into Ceres. I don't know how the angular resolution of the spectrometer compares with the size of spot 5, which is also important. Finally, the material could be some sort of mix of different minerals (I've almost given up on it being ice), which would make a unique identification of the composition harder.

Posted by: ZLD Jun 28 2015, 03:52 AM

The more I look at the images of the various spots around Ceres, the more I'm convinced they are very similar and very possibly all calderas.

Spot 1 and Spot 5 share a lot of similar features and I think they both may be calderas.




Yellow: lava flows
Green: particularly dark sediment only present in a few locations shown so far
Blue: vents

Other similarities include:
-exceptionally rough appearing terrain surrounding the craters compared to most other craters on the surface
-highly vertical crater walls surround most of the depressions, again, unique to these craters
-white material present, presumably from eruptive events

Posted by: Gladstoner Jun 28 2015, 10:53 PM

The ejecta sheet around the largest crater in the attached images has an etched appearance....

PIA19580:



PIA19583:

Posted by: Phil Stooke Jun 29 2015, 05:10 PM

http://photojournal.jpl.nasa.gov/jpeg/PIA19584.jpg

The spots in all their glory! - or not. But at least not overexposed. I still don't know what they are.

Phil


Posted by: ugordan Jun 29 2015, 05:24 PM

That image looks like it's in severe need of some 2.2 gamma...


Posted by: Gladstoner Jun 29 2015, 05:26 PM

The problem is that it is still very difficult to discern any topographic detail.

In the coming months (or years), will it be possible for Dawn to get close-ups (LAMO?) of the spots at an extremely low illumination angle?

Posted by: Mongo Jun 29 2015, 05:38 PM

QUOTE (ugordan @ Jun 29 2015, 06:24 PM) *
That image looks like it's in severe need of some 2.2 gamma...

Same image with 2.0 gamma, and with 2.0 gamma plus 2.0 contrast:


 

Posted by: Habukaz Jun 29 2015, 06:03 PM

This is what Dawn PI Christopher Russell said about the bright spots recently:

QUOTE
“We do see the contour of the ground, and it seems that it is not a hill but possibly a dip in the surface that is bright, but we need to complete the survey orbits in order to accurately obtain the topography of the area.”


http://www.latimes.com/science/sciencenow/la-sci-sn-ceres-pyramid-bright-spots-dawn-nasa-dwarf-planet-20150626-story.html

In the latest image with shorter exposure time it does look a bit to me like something bright sitting in some sort of cavity or depression lighting up the walls or slope of whatever it is sitting in. The dark protrusion to the left in the image below could be something at a higher elevation blocking the light, while the bright spot "on it"/directly left of it could be bright material ejected onto it.


Posted by: Fran Ontanaya Jun 29 2015, 06:53 PM

All the spots are contained within a circle offset to the left, like a smaller crater.

False colors added for whatever it may be worth.




Posted by: OrbitrapInSpace Jun 29 2015, 08:02 PM

(Full inline quote edited, see rule 3.5- MOD)

QUOTE (fredk @ Jun 22 2015, 04:29 PM) *


When looking at this animation for some time, one gets the feeling that the 3 most intense spots are lying on a crack, and the most intense spot shows filling of the crack
furthermore, their aspects reminds me of sulfur like deposits around vents (fumaroles) in volcanic areas.
I would propose a geyser like mechanism implying liquid material with fast evaporation and temperature reduction, leading to calcite deposits, travertine like, similar to the turkish Pamukkale enormous and incredibly white deposits, based on hot springs.

Posted by: nprev Jun 29 2015, 08:20 PM

...I think that you're reading WAYYY too much into this very limited dataset.

Obviously we're going to have to wait for much more detailed imagery from lower orbital altitudes to even begin to understand this enigmatic feature.

Posted by: ZLD Jun 29 2015, 08:44 PM

Best I can do here.




(click to animate)

Whatever this is, is still not resolved. Back on my previous posts, I continue to see similar "flows" and elements that relate to volcanic events. Going to stick with that I think. smile.gif

As for the bit that looks like a crack, I think that may be more similar to the dark streak in Spot 1. It initally seemed like a crack to me as well but it doesn't ever seem to have any highlights that you would expect to see with a feature that either dips below or extends above the surface.

Also, I'd highly agree with the PI opinion here. I think that it was previously shown that a crater wall could be seen in the RC3 animation. Personally, I think it probably looks like a much smaller Spot 1 within a larger crater. A somewhat recently opened caldera within a larger caldera.

And one last thing, I can't imaging the natural Ceres albedo being much lower than this latest image. That means that Spot 5 must have a pretty significant magnitude right?

Posted by: ngunn Jun 29 2015, 10:15 PM

Somebody, please, explain to me why it isn't just a recent impact into an ice deposit.

Posted by: ZLD Jun 29 2015, 10:20 PM

QUOTE (ngunn @ Jun 29 2015, 04:15 PM) *
Somebody, please, explain to me why it isn't just a recent impact into an ice deposit.


It may be ngunn but I've personally been uploading data to form a case showing that it may be volcanic in origin.

Posted by: John Broughton Jun 29 2015, 11:59 PM

QUOTE (ngunn @ Jun 29 2015, 10:15 PM) *
Somebody, please, explain to me why it isn't just a recent impact into an ice deposit.

Just as I suspected, there's a hill at the centre of Spot 5, rather than a crater. Bear in mind it is illuminated from below (south) in the original image. The secondary spot to its east also shows signs of positive relief.

Posted by: Gladstoner Jun 30 2015, 12:33 AM

QUOTE (ngunn @ Jun 29 2015, 05:15 PM) *
Somebody, please, explain to me why it isn't just a recent impact into an ice deposit.


The spots could be due to impacts, but not just impacts. The white material likely was emplaced here by some localized process.

Posted by: FOV Jun 30 2015, 12:38 AM

How will Dawn map/measure the topography? I believe there is no LIDAR onboard like LRO, for eg.?



Posted by: Gladstoner Jun 30 2015, 01:01 AM

QUOTE (FOV @ Jun 29 2015, 06:38 PM) *
How will Dawn map/measure the topography? I believe there is no LIDAR onboard like LRO, for eg.?


(Edit: for the white areas,) Dawn could take stereo images at sufficiently low solar illumination to bring out hard shadows. A couple topographic features are already sharply visible due to such shadows:


Posted by: djellison Jun 30 2015, 01:40 AM

QUOTE (FOV @ Jun 29 2015, 05:38 PM) *
How will Dawn map/measure the topography? I believe there is no LIDAR onboard like LRO, for eg.?


Stereo imaging and shape from shading.

There is a rather exceptional shape model generated from Dawn data for Vesta. The same will happen with Ceres.

Posted by: John Broughton Jun 30 2015, 02:00 AM

QUOTE (Gladstoner @ Jun 30 2015, 12:33 AM) *
The spots could be due to impacts, but not just impacts. The white material likely was emplaced here by some localized process.

That's unlikely, given it is sitting on a crack that is part of a deep and extensive network of cracks.

Even Spot 1 crater has cracks but they're hard to trace under the deposits and regolith. A mound with a possible depression at its centre is located at an intersection of cracks, some of which I've highlighted.

Posted by: Gladstoner Jun 30 2015, 03:08 AM

QUOTE (John Broughton @ Jun 29 2015, 08:00 PM) *
That's unlikely, given it is sitting on a crack that is part of a deep and extensive network of cracks.
Even Spot 1 crater has cracks but they're hard to trace under the deposits and regolith. A mound with a possible depression at its centre is located at an intersection of cracks, some of which I've highlighted.

I would place your scenario under 'localized' and 'not just impacts'. By localized, I mean material that is not in the form of an extensive, Ceres-wide substrate (e.g. like the bright ice exposed on Ganymede & Callisto). I would consider white stuff deposited along fractures to be localized. Such stuff potentially could either be exposed and scattered due to an impact, or have erupted on the surface, possibly with the 'help' of an impact to disrupt and weaken the overburden, or both.

Posted by: normr Jun 30 2015, 03:57 AM

QUOTE (Fran Ontanaya @ Jun 29 2015, 10:53 AM) *
All the spots are contained within a circle offset to the left, like a smaller crater.

False colors added for whatever it may be worth.




Just curious, how big do you think the largest bright spot is. Are we talking a city block, or several miles in diameter, or less. Same question for the smaller spots.

One other thought I had. Is it possible for the the white spots to be florescent? IE, could they glow in the dark? Excuse me if that sounds like a nutty question. Ignorance is bliss I suppose. blink.gif

Norm

Posted by: John Broughton Jun 30 2015, 05:44 AM

For what it's worth, my interpretation of the spots is that they begin with impacts that pressurise the putative ocean and cause water to erupt out of weak points elsewhere in the crust, particularly at fault junctions. Eruptions could therefore recur at different spots simultaneously after long intervals.

In the intervals, some spots slowly deposit salt via geysers, due to the squeezing effect on the ocean by the gradually-thickening crust as it freezes. Spot-5 could be a recently-active example of that.

At the next impact-triggered eruption, mud is deposited and salt may be excavated and displaced. Evidently, eruptions at spot-1 have been so great as to overflow the crater, deposit blocks of crust on its flanks and broaden the base. Steepness of the inner wall may be evidence of erosion by a transient lake, before it drained or froze and sublimated away.

Posted by: centsworth_II Jun 30 2015, 07:33 AM

QUOTE (normr @ Jun 29 2015, 10:57 PM) *
Just curious, how big do you think the largest bright spot is...
Based on a diameter for Ceres of 950 km and so a circumference of 2983 km and my estimate that the crater in which the spots are found is 1/32 the circumfrence, I get a crater diameter of about 93 km and an estimated diameter of the large spot of 13 km (8 mi).

The spots are not visible in images where the sun is not shining on them.

Posted by: pitcapuozzo Jun 30 2015, 10:29 AM

QUOTE (normr @ Jun 30 2015, 05:57 AM) *
Just curious, how big do you think the largest bright spot is. Are we talking a city block, or several miles in diameter, or less. Same question for the smaller spots.


According to http://www.jpl.nasa.gov/news/news.php?feature=4633: "At least eight spots can be seen next to the largest bright area, which scientists think is approximately 6 miles (9 kilometers) wide." The crater is 55 miles (88 km) wide.

Posted by: ZLD Jun 30 2015, 01:32 PM

I'm not sure why but I neglected to rotate the spot 5 image right side up, so that we were looking at it from a more natural angle.

Here, the sun is coming from above the image, at a somewhat sharp angle, probably similar to 9-10AM here.




(click to animate)

We'd really need a good couple of images back to back but it looks like, and I'm being hopeful with this enlargement, the bright streaks on the right of the brightest spot, could be coming up and away from the ground. Like an outgassing event. Doesn't make sense and it could very well likely be streaks going down the side of a hill. Just thought it was interesting to note.

Below is a image showing where I think the rim of the crater is. It almost looks like it is filled with something that was overbrimming.


Posted by: fredk Jun 30 2015, 02:28 PM

Here's a comparison of the last two underexposed images. I've done a rotation and vertical compression of the first image to get approximate registration of the two images, but there remains some geometrical distortion (ie, shear) between the two. But this shows that some of the details we're seeing are likely real, since they are present in both images, eg a couple of very small dark spots within the main bright spot:


It may look like some features move between the frames, but it is just the remaining distortion. There is no sign in these images of any time-dependent behaviour (eg, outgassing events), nor in any of the other images we've seen - in particular, the long rotation sequence that showed the spot over a full half rotation.

Posted by: John Broughton Jun 30 2015, 03:21 PM

I applied a used-defined transfer function to display the full range of brightness levels in a single image.


The bright spot looks like a hill on a crack to me. If it lies in a depression, it's an irregular one -- more like those in central pit craters than a circular impact structure.

Posted by: ZLD Jun 30 2015, 04:20 PM

Thanks for kicking me straight Fred.

I should have just done a morph in the first place. Below is the result.


(http://i.imgur.com/HYp5ZBr.gif)

For perspective, the ground at the bottom is in the foreground and coming upward as Ceres rotates away from the viewer.

The ground seems much more complex than I initially imagined. The crater wall I previously outlined may still be such a thing but rather than on a larger mound, everything seems to be recessed into a pit where the brightest area, is a wall at the back. Which really doesn't make sense to me when considering the sun angle.

Maybe the most interesting item I see in this is the dark patch on the right, appears to be hanging out and into the depression, suggesting the ground has collapsed.

Posted by: Habukaz Jun 30 2015, 04:33 PM

Carol Raymond on the big mountain:

QUOTE
Listening to Carol Raymond tell Dawn results at Ceres. The "pyramid" or cone has bright streaks running down its side. No explanation. Cool!


https://twitter.com/DrPhiltill/status/615908430872711168

I guess you can see hints of these streaks in the images released thus far.

Posted by: MarsInMyLifetime Jun 30 2015, 05:15 PM

QUOTE (John Broughton @ Jun 30 2015, 10:21 AM) *
I applied a used-defined transfer function to display the full range of brightness levels in a single image.


The bright spot looks like a hill on a crack to me. If it lies in a depression, it's an irregular one -- more like those in central pit craters than a circular impact structure.

John, your leveled image is the most truthful of the current ones for examination, in my opinion. I'd suggest considering the two straight bars to be the shaded parts of two opposing promontories that thrust into a basin that holds the brighter material. We might ascertain from the leftward spots that the material's brightness may vary with thickness of distribution, which would indicate that the brightest spot is either more pristine, thicker, or the origin for all the light material. The apparently rimmed spot on the rightmost 'promontory' may be all due to a rampart crater, which I would expect to see more of on an icy world, but I withhold that interpretation for now because I think we need to understand first whether these are promontories or scarps (which imply quite different formation processes).

Posted by: charborob Jun 30 2015, 05:43 PM

Today's image shows what looks like a flow lobe probably caused by the impact that created the fresh crater near the center of the image:


(image enlarged 2x and cropped)

Posted by: FOV Jun 30 2015, 07:45 PM

From latest image I thought the uneven surface of this crater was interesting. One of the loopy mounds looks darker than the others. The green arrow points at 2 mounds/peaks at or near the center of the large featured crater.




Posted by: John Broughton Jul 1 2015, 01:41 AM

QUOTE (MarsInMyLifetime @ Jun 30 2015, 05:15 PM) *
John, your leveled image is the most truthful of the current ones for examination, in my opinion. I'd suggest considering the two straight bars to be the shaded parts of two opposing promontories that thrust into a basin that holds the brighter material. We might ascertain from the leftward spots that the material's brightness may vary with thickness of distribution, which would indicate that the brightest spot is either more pristine, thicker, or the origin for all the light material. The apparently rimmed spot on the rightmost 'promontory' may be all due to a rampart crater, which I would expect to see more of on an icy world, but I withhold that interpretation for now because I think we need to understand first whether these are promontories or scarps (which imply quite different formation processes).

ZLD's morph also gives the impression the spot sits in an irregular depression with promontories. But rather than promontories, they are more likely to be large blocks of crust displaced during past explosions as part of a debris field surrounding the spot. That goes a long way to explaining the fan-shaped blast patterns of dark material. For instance, the nearest obstruction lies only 2.5km west of the spot's centre, and there's no spray pattern in that direction. This correlation implies the site was a source of at least some of that far-flung dark material and that there have been multiple explosions.

I compared the reflectivity of the core of that spot to the normal surface in PIA19584 and found it to be as bright as snow. My opinion on the secondary spots is that they represent the fallout of minor geysers located on fault lines. The fact that they diminish in brightness smoothly from their centres, suggests material has been distributed onto the ground after being lofted, but their small size in some cases equates to an exit velocity comparable with that of a lawn sprinkler!

Posted by: Habukaz Jul 1 2015, 04:51 PM

Can't say that the mountain looks that much like a stereotypical volcano in http://photojournal.jpl.nasa.gov/catalog/PIA19586 (although I've heard that some volcanoes don't care about their appearance):




Also, http://www.uahirise.org/ESP_041208_1755 (via https://twitter.com/ridingrobots/status/616278435950792704):



(one point to the impact hypothesis)

Posted by: Gladstoner Jul 1 2015, 04:56 PM

QUOTE (Habukaz @ Jul 1 2015, 10:51 AM) *
Can't say that the mountain looks that much like a stereotypical volcano in http://photojournal.jpl.nasa.gov/catalog/PIA19586


It reminds me of Middle Butte in Idaho:

https://www.google.com/maps/@43.4834575,-112.7606177,1340a,60y,67.03h,63.43t/data=!3m6!1e4!3m4!1s0x5355bc3d146d6da7:0x16c3b3d0e0292e42!2e0!3e18!6s%2F%2Fg2.gstatic.com%2Fheli%2Fimage%2F0x5355bc3d146d6da7_0x16c3b3d0e0292e42.jpg

Posted by: MarsInMyLifetime Jul 1 2015, 06:11 PM

QUOTE (Habukaz @ Jul 1 2015, 11:51 AM) *
Can't say that the mountain looks that much like a stereotypical volcano in http://photojournal.jpl.nasa.gov/catalog/PIA19586 (although I've heard that some volcanoes don't care about their appearance):

In the absence of any other apparently similar shapes on Ceres, a geological cause would have as much probability as a one-time external cause. I dislike explanations that require many conditions, but is there any possible case here for a low-energy touchdown of a large, loosely-consolidated mass that formed a classic anthill after disassociating? This strains Occam's Razor in so many ways, but so does the "single geological event over 4 billion years" in my mind. If there were just one more such shape instance we could find, the odds for external causation quickly vanish.

Posted by: ZLD Jul 1 2015, 06:18 PM

Morph from SO18 with SO6.


(http://i.imgur.com/yXXDbws.gif)

Strange topography with what can be seen. I may come back to this and try to easy out some more detail with some better contrast.

Doing this morph, I saw several areas that looked like potential flow remnants. If it was formed similar to a shield volcano, it hasn't erupted much more than a trickle. in a long time. Possibly the outer shell has worn away. I find its existence difficult to explain without suggesting it was some form of volcano at some point, even if it never erupted.

I do find it extremely interesting that the black material that surrounds the top (or tops, as there may be 2?) and a small bit at the bottom, is very similar to the black material in Spot 1 which is far away; and not to forget the presence of more of the white material.

Edit: Quick note, I should point out that there is a small crater at the center of each dark patches at the top of the mound. You may have to zoom in more to view them. Ctrl+ should do the trick in most browsers.

Posted by: dvandorn Jul 1 2015, 06:28 PM

Looking at the base of the mountain, it looks like the surrounding terrain embays the base of the mountain. In other words, the mountain was there first, and the surrounding surface was emplaced later, covering a lower base this mountain had before the resurfacing events that happened around it.

Most interesting is the crater directly next to the flat side of the mountain (on the left side of ZLD's image above). The little spit of surface between that crater and the mountain is also embayed against the mountain, but shows no signs of piling up material against the mountain. On the other hand, that side of the mountain is flattened. I suspect that the eject from that crater's impact blasted off some of the side of the mountain, and the resulting settling-out left the embayment looking like it does on the other sides of the mountain.

-the other Doug

Posted by: Gladstoner Jul 1 2015, 11:02 PM

QUOTE (dvandorn @ Jul 1 2015, 01:28 PM) *
Looking at the base of the mountain, it looks like the surrounding terrain embays the base of the mountain. In other words, the mountain was there first, and the surrounding surface was emplaced later, covering a lower base this mountain had before the resurfacing events that happened around it.


To me, the sharp edge of the mountain base indicates that a talus slope is lapping over a preexisting surface (probably impact regolith). But still, there could be an interbedding of regolith and talus debris:


Posted by: ngunn Jul 1 2015, 11:39 PM

QUOTE (dvandorn @ Jul 1 2015, 07:28 PM) *
the mountain was there first, and the surrounding surface was emplaced later


That's consisent with my suggestion that it is the remains of the central peak of an ancient basin now sunken in by isostasy or otherwise erased. It's not difficult to think of scenrios in which the central peak outlives the rest of the cater. Some of the other central peaks on Ceres look a bit similar, though they don't have flat tops

Posted by: ZLD Jul 2 2015, 02:33 AM

A central peak of 4 miles? There's a formula I'm sure, to define the likely size of a central peak from an impact of specific size/mass. How big did this impactor have to be to create a central peak 4+ miles high? Just guessing here, but I think an impactor that would be able to create a central peak of that height would have obliterated Ceres.

Posted by: TheAnt Jul 2 2015, 03:48 AM

At least it seem improbable, I like the idea of the streaks on the slopes being talus, and that part would explain in part the reason the surrounding terrain look dissimilar. In lack of any other explanation I go with the idea that it is a Pingo - even though the size of it also stretch poor William of Occam. =)

Posted by: Daniele_bianchino_Italy Jul 2 2015, 04:26 AM

QUOTE (ngunn @ Jul 2 2015, 12:39 AM) *
That's consisent with my suggestion that it is the remains of the central peak of an ancient basin now sunken in by isostasy or otherwise erased. It's not difficult to think of scenrios

ngunn, I Think Impossible The total cancellation of this hypotetical colossal crater.

QUOTE (ZLD @ Jul 2 2015, 03:33 AM) *
A central peak of 4 miles? I think an impactor that would be able to create a central peak of that height would have obliterated Ceres.

HI zld; Obliterated Ceres? I don't think.. Herscel crater on Mimas have a Central peak similAr or more tall, and Mimas is many smallest than Ceres. Ceres would resisted at similar or more big impact. hOwever, i think is a ping, dome or volcano formation.


Posted by: bsharp Jul 2 2015, 08:17 AM

Totally amateurish contrast enhancement, annotation and comparison of the mount snapshots.

It certainly looks like flows to the crater in the south. Could the "spoon" at the north be a "carving", how about the feature on the crater's rim?




Posted by: John Broughton Jul 2 2015, 03:16 PM

QUOTE (MarsInMyLifetime @ Jul 1 2015, 06:11 PM) *
If there were just one more such shape instance we could find, the odds for external causation quickly vanish.

You don't have to look far to find smaller versions of the mountain - every spot should have them. I've arrowed the largest in a field of about a dozen. It's situated on the mandatory fault line - the sharpest crack I've yet seen on the surface of Ceres.

Posted by: ZLD Jul 2 2015, 04:23 PM

Just to reiterate something I observed earlier, I think there may be a lot of calderas on Ceres that form cinder cones over some the vents. What caused the calderas, who knows. Maybe an small impact resulted in enough heat and pressure to form a short geologic event to form an upwelling, create a caldera and sometimes a cinder cone.

As for the depression next to the mound, it could have been caused by the collapse of a magma chamber like formation (aquifer?) from the mound erupting material. The nearby crater is a complete mystery though. I don't know that it could have impacted so perfectly next to the mound and not caused more damage to it. If white material were just under a thin dusting of gray material, we should be able to expect that it would have blasted it all over the area around it, rather than just onto the side of the mound as well.

All three features seem to fit together so well that they almost have to share some sort of common story.

Posted by: MarsInMyLifetime Jul 2 2015, 08:16 PM

The views in bsharp's post now seem to indicate that the slope facing the large crater is mantled with original surface, replete with dark regolith and craters not evident on the more scree-like slopes. Now I see this feature as an upthrust fault, not as a deposited cone.

Posted by: Steve G Jul 3 2015, 06:13 PM

The streaks on the cone are limited to the cone. It almost looks like someone just photoshopped it in place. If it was a volcanic cone, the flow would extend to the surface, so an uplift makes more sense to my untrained eye.

Posted by: ZLD Jul 3 2015, 06:53 PM

QUOTE (MarsInMyLifetime @ Jul 2 2015, 03:16 PM) *
The views in bsharp's post now seem to indicate that the slope facing the large crater is mantled with original surface, replete with dark regolith and craters not evident on the more scree-like slopes. Now I see this feature as an upthrust fault, not as a deposited cone.



Thats just an effect of sun incidence. Below is the animation I did during RC3 showing all faces glow in white when lit.


(http://i.imgur.com/Bx4epGE.gif)

Posted by: ngunn Jul 3 2015, 06:55 PM

QUOTE (Steve G @ Jul 3 2015, 07:13 PM) *
The streaks on the cone are limited to the cone.


That's what you'd expect if they're recently active screes on slopes close to the angle of repose.

Posted by: vikingmars Jul 3 2015, 11:54 PM

QUOTE (Daniele_bianchino_Italy @ Jul 2 2015, 06:26 AM) *
ngunn, I Think Impossible The total cancellation of this hypotetical colossal crater.
HI zld; Obliterated Ceres? I don't think.. Herscel crater on Mimas have a Central peak similAr or more tall, and Mimas is many smallest than Ceres. Ceres would resisted at similar or more big impact. hOwever, i think is a ping, dome or volcano formation.

WOW ! Thanks a lot Daniel for this very nice work ! smile.gif

Posted by: Daniele_bianchino_Italy Jul 4 2015, 07:08 PM

QUOTE (vikingmars @ Jul 4 2015, 12:54 AM) *
WOW ! Thanks a lot Daniel for this very nice work ! smile.gif

Thank's vikingmars many Thanks

Posted by: pitcapuozzo Jul 7 2015, 12:23 PM

So, with Dawn holding at 4400 km due to an attitude control anomaly and safe mode, I guess we'll have to update our flight plans. Arrival in HAMO (1450 km) was originally scheduled for August 4.

http://www.nasa.gov/jpl/dawn-holding-in-second-mapping-orbit

Posted by: Webscientist Jul 7 2015, 01:40 PM


A simulated flyover animation of the Spot 5 area based on an image obtained on June 6, 2015 from the Dawn probe (low resolution).
Artificial colors and Shape from Shading Technique!
The famous bright spots are too saturated to reveal anything unfortunately!

For a higher resolution of this animation from the cockpit:

https://www.youtube.com/watch?v=iiMR2MPGZac


 Spot5Unmanned07Juillet.wmv ( 802.21K ) : 271
 

Posted by: volcanopele Jul 8 2015, 01:20 AM

I've gone ahead and moved the discussion of the new Ceres feature names to http://www.unmannedspaceflight.com/index.php?showtopic=8051&hl=.

Posted by: Habukaz Jul 8 2015, 02:07 PM

QUOTE (Habukaz @ Jul 1 2015, 06:51 PM) *
Also, http://www.uahirise.org/ESP_041208_1755 (via https://twitter.com/ridingrobots/status/616278435950792704):



(one point to the impact hypothesis)


Here are the bright Martian spots in full resolution, via HiView (I've since learned that those JPEG downloads are typically not full resolution):




For viewing convenience, here is the central (brightest) portion:



Bright spots on Ceres:



I can't say they are a perfect match of one another (the Cerean feature is more compact?); but not very bad, either. On Mars, an impactor might have come from top-right, while on Ceres an impactor could have come from the left.


Posted by: Daniele_bianchino_Italy Jul 9 2015, 09:36 AM

mmm,Yes, very similar Habukaz.. blink.gif

Posted by: stevesliva Jul 10 2015, 05:05 PM

QUOTE (pitcapuozzo @ Jul 7 2015, 07:23 AM) *
So, with Dawn holding at 4400 km due to an attitude control anomaly and safe mode, I guess we'll have to update our flight plans. Arrival in HAMO (1450 km) was originally scheduled for August 4.

http://www.nasa.gov/jpl/dawn-holding-in-second-mapping-orbit


I had missed this. Safe mode June 30th. The last full Marc Rayman update was June 29th.

AWST has some recent quotes from Dr. Rayman here:
http://aviationweek.com/blog/dawn-prolongs-2nd-reconnaissance-orbit-ceres-after-orientation-issue

Dwarf planet spacecraft safe mode party over Independence Day weekend. Sheesh.

Posted by: OWW Jul 10 2015, 07:22 PM

Thanks for that link. But doesn't

QUOTE
Just prior to entering safe mode, Dawn's telemetry revealed resets of the computers that manage cameras and an infrared mapping spectrometer on the probe.

contradict the earlier statement?:
QUOTE
NASA's Dawn spacecraft is healthy and stable, after experiencing an anomaly in the system that controls its orientation.

Since when are the cameras and spectrometer part of the navigation system?

Posted by: stevesliva Jul 10 2015, 07:33 PM

The 6/29 Dawn Journal discusses the instrument anomaly... the real safe mode happened 6/30.

Posted by: TheAnt Jul 11 2015, 06:43 AM

QUOTE (Habukaz @ Jul 8 2015, 04:07 PM) *
Here are the bright Martian spots in full resolution, via HiView.

I can't say they are a perfect match of one another (the Cerean feature is more compact?); but not very bad, either.
...one point to the impact hypothesis.


You've made a very good case for the impact hypothesis Habukaz, you've almost convinced me I've been barking up the wrong tree about this feature. =)
We'll see when Dawn gets sorted out and get to take images at HAMO distance in a few weeks.

Posted by: Sherbert Jul 11 2015, 05:20 PM

I see Calderas, sinkholes and impact craters in many places and I think all three processes have played a part in the surface topology we see today. Don't give up on Cryovolcanism just yet Ant.

Posted by: Phil Stooke Jul 12 2015, 12:27 AM

OWW:

Thanks for that link. But doesn't

"Just prior to entering safe mode, Dawn's telemetry revealed resets of the computers that manage cameras and an infrared mapping spectrometer on the probe."

contradict the earlier statement?:

"NASA's Dawn spacecraft is healthy and stable, after experiencing an anomaly in the system that controls its orientation."

Since when are the cameras and spectrometer part of the navigation system?

-----------------------------------------------------------------------------------
Not necessarily a contradiction. An anomaly in one system can cause a problem which results in a reset elsewhere. I don't know the chain of events, but it's not necessarily a contradiction.

Phil

Posted by: John Broughton Jul 12 2015, 12:32 AM

QUOTE (Habukaz @ Jul 8 2015, 02:07 PM) *
Here are the bright Martian spots in full resolution...

You're comparing apples with oranges. There's no atmosphere on Ceres to disrupt rubble piles. Its gravitational field is too feeble and the Roche limit too close, to result in anything other than single impact craters.

Quite apart from that, there's no evidence on steep slopes of the existence of a bright layer of material anywhere near the surface.

Posted by: nprev Jul 12 2015, 02:28 AM

There's no evidence for bright material on the steep slopes of Husband Hill near Spirit either, John, yet the rover inadvertently exposed such by dragging its stalled wheel. Absence of evidence is not evidence of absence.

Additionally, I see no reason why 'rubble pile' loose associations of meteoroids might not exist, esp. in the main asteroid belt. Small objects formed in effectively zero gravity may well break apart over time from thermal stresses yet remain in close proximity to each other for an extended period of time.

I find an impact origin for these bright spots by far the most compelling hypothesis to date. Hopefully higher-resolution imagery will soon resolve this debate.

Posted by: Habukaz Jul 12 2015, 09:27 AM

Not only could the asteroid have been in "flying formation" already, but the other spots east of the "primary" could just be secondary craters - either excavated by fragments of the impactor itself or surface material it sent flying in a "direct fire" way (i.e. with a non-parabolic path).

Posted by: John Broughton Jul 12 2015, 10:54 AM

QUOTE (nprev @ Jul 12 2015, 02:28 AM) *
There's no evidence for bright material on the steep slopes of Husband Hill near Spirit either, John, yet the rover inadvertently exposed such by dragging its stalled wheel. Absence of evidence is not evidence of absence.

As I recall, that material is actually regarded as having originated in solution deep underground, prior to deposition on the surface via a spring or geyser - exactly what I've been arguing for to explain the spots on Ceres.
QUOTE
Additionally, I see no reason why 'rubble pile' loose associations of meteoroids might not exist, esp. in the main asteroid belt. Small objects formed in effectively zero gravity may well break apart over time from thermal stresses yet remain in close proximity to each other for an extended period of time.

The time any recently-separated components of a rubble-pile asteroid spend in close proximity with one another, would be an extremely small fraction of their total lifespan, and the odds of colliding with another asteroid during that interval would be equally astronomical!
QUOTE
I find an impact origin for these bright spots by far the most compelling hypothesis to date. Hopefully higher-resolution imagery will soon resolve this debate.

The central spot looks nothing like an impact crater. The debate should be resolved once and for all when their chemical composition is announced. I'm expecting ice and salt at spots inside Occator crater and salt at all the others. Also looking forward to colour images to see if any spots display a brown hue indicative of radiation-darkened salt.

Posted by: TheAnt Jul 12 2015, 04:08 PM

QUOTE (Sherbert @ Jul 11 2015, 07:20 PM) *
I see Calderas, sinkholes and impact craters in many places and I think all three processes have played a part in the surface topology we see today. Don't give up on Cryovolcanism just yet Ant.


Oh I am not. I said "almost", and in doing so giving credit for Habukaz presenting his interpretation very well. =)
I still think the most likely outcome will be that most of the lighter areas to have salts, with Occator being the exception.

There's a few siblings in craters that lack central peaks that have a pit that look similar even though not being bright. And we mentioned that earlier, that the remaining salt in those cases might simply have been dusted over.
And as John Broughton pointed out right before me, the central pit does not look like an impact crater in Occator neither do the pits in the other craters that have a similar formation.

Posted by: alk3997 Jul 15 2015, 04:14 PM

According to the Dawn website's graphics, the Dawn spacecraft is thrusting again. It is now at 2,680 miles above Ceres and descending.

Andy

Posted by: dvandorn Jul 15 2015, 05:22 PM

It has been since before the 6/30 safing event that we've had any image releases. Now they're changing orbits, but either 1) haven't gotten the cameras working again, or 2) haven't seen fit to release any images taken since the safing event?

Something seems wrong, there. The Dawn team has not been very reticent about releasing images, and I'd think if they had begun taking pictures again, we'd have seen at least one of them.

I wonder if there is something more seriously wrong with Dawn than we've been told?

-the other Doug

Posted by: fredk Jul 15 2015, 05:28 PM

If you look at http://photojournal.jpl.nasa.gov/mission/Dawn they've typically released images that are about 2 weeks old. So you might expect post-safing images soon...

Posted by: alk3997 Jul 15 2015, 05:59 PM

QUOTE (dvandorn @ Jul 15 2015, 11:22 AM) *
It has been since before the 6/30 safing event that we've had any image releases. Now they're changing orbits, but either 1) haven't gotten the cameras working again, or 2) haven't seen fit to release any images taken since the safing event?

Something seems wrong, there. The Dawn team has not been very reticent about releasing images, and I'd think if they had begun taking pictures again, we'd have seen at least one of them.

I wonder if there is something more seriously wrong with Dawn than we've been told?

-the other Doug


I suspect that's normal. Remember taking photos requires sequences to make the spacecraft work. Making sequences requires testing and uplinking and planning. Those don't happen overnight. So just because Dawn was parked in orbit doesn't mean they could just press the "camera shutter" again.

It also could be because they didn't want to steal any of NH's thunder.

Andy

Posted by: Daniele_bianchino_Italy Jul 16 2015, 02:38 PM

You confirms that this Unnamed crater in 9,8 Km in diameter about?
(the description indicate 410m per pixel)-
http://photojournal.jpl.nasa.gov/catalog/PIA19595


 

Posted by: TheAnt Jul 16 2015, 03:25 PM

QUOTE (dvandorn @ Jul 15 2015, 07:22 PM) *
Something seems wrong, there. The Dawn team has not been very reticent about releasing images, and I'd think if they had begun taking pictures again, we'd have seen at least one of them.
I wonder if there is something more seriously wrong with Dawn than we've been told?

-the other Doug


I seriously don't think so, since Dawn lost that gyro the management of the spacecraft focus on orientation while the engines are active, having to turn Dawn to snap images would add one unnecessary complication to the orbit.

Edit: I should have checked the status update also, I knew they were supposed to have finished the troubleshooting. But was unaware of this system checkout, so until all testing is done Dawn might not do any kind of observations until the craft have gotten a 'cured and curious' clean bill of health.

Posted by: Phil Stooke Jul 16 2015, 03:40 PM

Dvandorn: "It has been since before the 6/30 safing event that we've had any image releases. Now they're changing orbits, but either 1) haven't gotten the cameras working again, or 2) haven't seen fit to release any images taken since the safing event?"

Doug, there is a new image every weekday at:


http://dawn.jpl.nasa.gov/multimedia/images/


Taken in the earlier orbit, admittedly, but new releases every day. That's what I would expect given thrusting, anomaly, Pluto.

Phil

Posted by: Habukaz Jul 16 2015, 04:41 PM

Read http://dawn.jpl.nasa.gov/mission/status.html whenever one wants to know what's up for Dawn.

http://photojournal.jpl.nasa.gov/catalog/PIA19596 shows Kerwan.

Posted by: Gladstoner Jul 16 2015, 04:52 PM

A good close-up of the 'sand dollar' basin has been released on the NASA photo journal:

http://photojournal.jpl.nasa.gov/catalog/PIA19596

(Edit: Already posted above. A day late and a sand dollar short....)

Posted by: Gladstoner Jul 16 2015, 10:36 PM

The latest image is rotated 45 degrees from the latitude-longitude grid. I don't recall any other images that are not oriented normally.

Posted by: Habukaz Jul 17 2015, 06:12 PM

Yes! Finally we are moving down to HAMO. smile.gif

https://twitter.com/NASA_Dawn/status/622105938158223360

Posted by: nogal Jul 17 2015, 11:14 PM

This NASA http://dawn.jpl.nasa.gov/news/news-detail.html?id=4659 has a Mission Status Report providing an account of the problem and its remediation.
Fernando

Posted by: Gladstoner Jul 18 2015, 12:38 AM

QUOTE (Gladstoner @ Jul 16 2015, 05:36 PM) *
The latest image is rotated 45 degrees from the latitude-longitude grid. I don't recall any other images that are not oriented normally.

This could explain the orientation of the image:

"The spacecraft experienced a discrepancy in its expected orientation on June 30, triggering a safe mode. Engineers traced this anomaly to the mechanical gimbal system that swivels ion engine #3 to help control the spacecraft's orientation during ion-thrusting."

http://dawn.jpl.nasa.gov/news/news-detail.html?id=4659

Posted by: Pete B. Jul 18 2015, 01:33 AM

QUOTE (dvandorn @ Jul 15 2015, 05:22 PM) *
It has been since before the 6/30 safing event that we've had any image releases. Now they're changing orbits, but either 1) haven't gotten the cameras working again, or 2) haven't seen fit to release any images taken since the safing event?


-the other Doug



I think I read somewhere that there will be no images taken during the transition to HAMO. But I haven't found that statement again despite searching for it.

Posted by: Bill Harris Jul 18 2015, 12:52 PM

QUOTE (Phil Stooke @ Jul 16 2015, 10:40 AM) *
Doug, there is a new image every weekday at:


http://dawn.jpl.nasa.gov/multimedia/images/


Taken in the earlier orbit, admittedly, but new releases every day....

Phil


And continuing a fine series of Survey Orbit imagery. #29 by current count.

--Bill

Posted by: dvandorn Jul 18 2015, 06:32 PM

I know. I just hadn't yet seen an image acquired since the safing event, and was a touch concerned, is all. I have no problems with the beautiful images the team does post, I appreciate the Pictures of the Day a lot. Loved it back at Vesta and love it now.

I just asked because it had been a couple of weeks since the safing event and hadn't seen anything indicating they were taking pictures again. Thanks for the reassurance, you guys.

-the other Doug

Posted by: Gladstoner Jul 20 2015, 07:46 PM

New image:

http://photojournal.jpl.nasa.gov/catalog/PIA19599

Bits of white stuff are scattered on the rims and ejecta sheets of at least four relatively fresh craters. It'd be interesting to compare and contrast with similar craters on various parts of Ceres.

Posted by: FOV Jul 21 2015, 07:00 PM

A crop and zoom of portion of PIA 19600: a sloppy crater, weird cross hatch cracks near the lower edge and another fleck of the uber bright stuff near the top.


Posted by: Phil Stooke Jul 21 2015, 07:19 PM

How's this for a tweet?


Andy Rivkin ‏@asrivkin:
Russell: Can see haze in crater with bright spots at some local times. Bright spots "indicate Ceres is active today." #nesf2015


Chris Russell at the NASA Exploration Science Forum.

Phil


Posted by: scalbers Jul 21 2015, 07:24 PM

Pretty remarkable tweet. Did we earlier see a hazy appearance to the edges of the Spot #5 in Occator in some posted images?

Posted by: FOV Jul 21 2015, 07:25 PM

Wow.

Posted by: Habukaz Jul 21 2015, 07:32 PM

Very bold statement. It does jibe with the "bright spot is visible when it shouldn't" line that we got earlier. Let's see what evidence they got.

Posted by: Explorer1 Jul 21 2015, 07:52 PM

Wow.... that would pretty much wrap up the salt deposit hypothesis, right?

Posted by: Habukaz Jul 21 2015, 08:28 PM

What appears to be a 3D model of Occator:



https://twitter.com/snnaka/status/623571917165821952

Posted by: Steve5304 Jul 22 2015, 01:47 AM

I also see four anomalies in the crater..dark strips or something. Could be plumes or something of whats causing the phenomenom

Posted by: nprev Jul 22 2015, 01:54 AM

Let's wait for the mission scientists to declare the discovery of liquid water. 'Warm' ice could conceivably sublimate to form a mist of sorts, esp. if it's rapidly cooling again & recombining into ice crystals.

Bottom line: Interesting stuff, but not enough to draw conclusions. wink.gif

Posted by: Steve5304 Jul 22 2015, 01:57 AM

QUOTE (nprev @ Jul 22 2015, 02:54 AM) *
Let's wait for the mission scientists to declare the discovery of liquid water. 'Warm' ice could conceivably sublimate to form a mist of sorts, esp. if it's rapidly cooling again & recombining into ice crystals.

Bottom line: Interesting stuff, but not enough to draw conclusions. wink.gif



You are correct...but for the record. Herschel detected liquid water erupting from somewhere.


Im all sorta of excited for the LAMO orbit

Posted by: centsworth_II Jul 22 2015, 02:05 AM

QUOTE (Phil Stooke @ Jul 21 2015, 03:19 PM) *
How's this for a tweet?...
The blog entry:
"Russell’s update began with some relatively mundane results.... Russell then began to discuss the surface features on Ceres, and things rapidly became much less mundane."
http://www.planetary.org/blogs/guest-blogs/2015/0721-dawn-at-ceres-a-haze-in-occator-rivkin.html

Posted by: nprev Jul 22 2015, 02:10 AM

QUOTE (Steve5304 @ Jul 21 2015, 05:57 PM) *
You are correct...but for the record. Herschel detected liquid water erupting from somewhere.


Not aware that any such claim was made. Water vapor was detected; that does not imply liquid water.

Posted by: Steve5304 Jul 22 2015, 02:23 AM

QUOTE (nprev @ Jul 22 2015, 03:10 AM) *
Not aware that any such claim was made. Water vapor was detected; that does not imply liquid water.



Not to argue semantics but water vapor implies evaporation of a liquid source that replenishes. Even if if the liquid is temporary

Posted by: nprev Jul 22 2015, 02:32 AM

That is not correct. Althoughhttp://startswithabang.com/wp-content/uploads/2008/08/water-phase-diagram.jpg is not to scale, please note that the liquid phase is not possible at atmospheric pressures below 6 mb, which is obviously far higher than the effective vacuum on Ceres.

Ice on the surface of Ceres would sublimate directly into vapor if exposed to enough heat. Therefore, a plausible explanation for the purported 'mist' in Oculus may be local solar heating of ice.

Posted by: Bill Harris Jul 22 2015, 07:29 AM

QUOTE (Gladstoner @ Jul 20 2015, 02:46 PM) *
Bits of white stuff are scattered on the rims and ejecta sheets of at least four relatively fresh craters. It'd be interesting to compare and contrast with similar craters on various parts of Ceres.


Yep, and I'm starting to notice "white" spots on crater rims and on the plains. It seems that many of the light areas we saw early on were unresolved white spots. And given recent observations it would seem that Ceres is subtly more active than we imagined. It will be interesting to get some spectral data from these white spots when Dawn gets down to the Mapping Orbits.

--Bill

Posted by: climber Jul 22 2015, 08:59 AM

QUOTE (Bill Harris @ Jul 22 2015, 09:29 AM) *
when Dawn gets down to the Mapping Orbits.

--Bill

She was supposed to start on July 15th but was kind enough to let NH show happen.
Do you all realise that we have now exploring 3 active worlds at the same Time?
Go Dawn, go NH, go Rosetta (and wake up Philae).

Posted by: DFinfrock Jul 22 2015, 12:55 PM

Climber, Mars is active too.
Global dust storms, dust devils, lower-speed wind transport and erosion, gully features in some craters, sublimation and deposition of CO2 in polar terrain, just to mention a few.

Posted by: Bill Harris Jul 22 2015, 01:42 PM

And Cassini.

Posted by: climber Jul 22 2015, 01:43 PM

QUOTE (DFinfrock @ Jul 22 2015, 02:55 PM) *
Climber, Mars is active too.
Global dust storms, dust devils, lower-speed wind transport and erosion, gully features in some craters, sublimation and deposition of CO2 in polar terrain, just to mention a few.

You're right...but not as active as UNMSF those weeks laugh.gif

Posted by: ZLD Jul 22 2015, 02:13 PM

Well this is exciting. 'Active' is an interesting world choice. Does sublimation get counted as an active event in all cases? I would say that if a low velocity, icy impactor were to leave fractured chunks and began sublimating away, this would not constitute an active event. However, if the sublimation is present within the surface and is modifying the terrain, this could be then considered an active event.

Four big questions pop out at me with this news:

-If Occator is a location for active sublimation, where did the ice come from?

-If Occator is a location for active sublimation, with hundreds of larger and smaller white spots that may be related, why is Occator possibly the only active region among them?

-If Occator is a location for active sublimation, what role does the white material play in the sublimation?

-If Occator is a location for active sublimation, does local or global transport exist?

Really wish we were getting the same type of regular science updates with Dawn that we have been getting with NH. Dawn is just as interesting but the teams public outreach efforts seem to be night and day almost.

Posted by: Bill Harris Jul 22 2015, 02:40 PM

It has to be more complex than just ice and sublimation.

--Bill

Posted by: dvandorn Jul 22 2015, 03:31 PM

All right, so, if they are seeing hazes over Occator at mid-day, where are the images that show this phenomenon? Will they be embargoed until someone can have a paper published about it? huh.gif

-the other Doug

Posted by: wildespace Jul 22 2015, 03:35 PM

Hmm, could it be underground salty water rising to the surface and evaporating, leaving the bright salt deposits?

Posted by: ZLD Jul 22 2015, 03:58 PM

I tried cleaning up the projected image of Occator.



QUOTE (dvandorn @ Jul 22 2015, 09:31 AM) *
Will they be embargoed until someone can have a paper published about it?


It seems this way from the lack of scientific news coming from the mission.

Posted by: ugordan Jul 22 2015, 04:08 PM

The Chris Russell talk is now available http://nesf2015.arc.nasa.gov/agenda (hat tip to nasaspaceflight.com user leovinus)

Posted by: ZLD Jul 22 2015, 06:10 PM

A while back I posted a highly processed closeup of Occator. Here is a much updated, reprocessed version of that, overlayed with the projected image.






(click to animate)

Ok, so if this method holds any water (haha...) I'm seeing what could be multiple cryovolcanoes near the brightest spot. It still isn't clear why there is other multiple much brighter spots. It would be exceedingly useful if the team could take another fast shutter image so the nature of the thin wispy streaks, could be determined (plumes or lava).

----------
Edit
----------
Here is another blink with the source data.


(click to animate)

Really looks like theres a caldera near the upper right that has some kind of wispy trail that may be up away from the surface. Not sure what we would exactly be looking for in a sublimation event on a body like Ceres but this looks like a good chunk of shiny ice in this pit.

Posted by: Habukaz Jul 22 2015, 06:12 PM

QUOTE (ugordan @ Jul 22 2015, 06:08 PM) *
The Chris Russell talk is now available http://nesf2015.arc.nasa.gov/agenda (hat tip to nasaspaceflight.com user leovinus)



So Russell actually suggests the haze could be caused by sublimation ("largest comet in the asteroid belt"); but also says the bright spots were not created by impacts? Getting a bit confusing.

Posted by: Steve5304 Jul 26 2015, 08:46 PM

Any news on hamo. When do we expect the first survey?

Posted by: Bill Harris Jul 26 2015, 09:29 PM

I'm starting my work in the Ceres Spots, beginning with Spot 5, Occator Crater:

https://univ.smugmug.com/Dawn-Mission/Ceres/i-sZKcT4r/1/X2/PIA19579--Spot5-Enh-d-X2.png

It will be interesting to see this resolved during the HAMO and LAMO phases of the mission. This is much akin to the TLPs (Transient Lunar Phenomena) studied in the '60's which were as controversial as the impact vs volcanic origins of lunar craters.

Info:
https://en.wikipedia.org/wiki/Transient_lunar_phenomenon

or Google "transient lunar phenomena" or "aristarchus lights" for more. Warning, it gets strange.

--Bill

Posted by: Herobrine Jul 27 2015, 05:33 PM

While we're waiting for HAMO, I thought I'd make a preview of what we can expect to see at HAMO and LAMO.
At the top are 3 frames from the survey orbit (originally 1024x1024). The middle row shows the spots from the frame above at their HAMO-equivalent scale. The bottom row shows the same spots at their LAMO-equivalent scale.


All images are shown at 25% actual image size.
I feel like this may have already been done before, and I didn't check through the forum, so my apologies if this is redundant.

Posted by: Steve5304 Jul 27 2015, 06:22 PM

QUOTE (Herobrine @ Jul 27 2015, 05:33 PM) *
While we're waiting for HAMO, I thought I'd make a preview of what we can expect to see at HAMO and LAMO.
At the top are 3 frames from the survey orbit (originally 1024x1024). The middle row shows the spots from the frame above at their HAMO-equivalent scale. The bottom row shows the same spots at their LAMO-equivalent scale.
[attachment=37260:orbits_25_percent.png]
All images are shown at 25% actual image size.
I feel like this may have already been done before, and I didn't check through the forum, so my apologies if this is redundant.



So, I would think HAMO orbit should able to solve the mystery or atleast answer some questions which will make new ones smile.gif

Posted by: Steve G Jul 28 2015, 12:05 AM

QUOTE (Steve5304 @ Jul 26 2015, 01:46 PM) *
Any news on hamo. When do we expect the first survey?


It's on their website.

They switched engines and are on their way.

http://dawn.jpl.nasa.gov/news/news-detail.html?id=4659

Posted by: pitcapuozzo Jul 28 2015, 02:50 PM

New topographic and themal maps of Ceres!

http://www.nasa.gov/jpl/dawn/new-names-and-insights-at-ceres

Also, I'm watching live the USHR10 hearing and Russell showed this nice image of the bright spots in Occator and the mountain.


Posted by: Habukaz Jul 28 2015, 04:35 PM

So Occator (and hence its spots) sits at the edge of a highland area, while the mountain sits in a lowland area. Hmm.


----

(unrelatedly: many months ago during approach, it was noted that it looked like the north some places was less cratered than the south. while that might not be the case, there is actually a north-south dichotomy some places in terms of altitude, such that the observations might have been of something real after all)

Posted by: Bill Harris Jul 29 2015, 03:01 PM

For those who need it, here is an add-on scale bar for the topography on the new Dawn Ceres map pia19607 (and it is useable with the cylindrical projection pia19606). The topography is represented +/- 7.5 km about a zero datum.

As suspected, this little world has some strange topography.

--Bill

 

Posted by: algorimancer Jul 29 2015, 04:40 PM

Looking at the topo map, there's something interesting going on with the Rongo depression (as had been evident in the opnav topo maps) -- I really want to think of it as a subduction zone. It is just to the west of the mountain (Hualani); perhaps a coincidence, perhaps not -- pretty common for mountains to form adjacent to subduction zones. There is also an unnamed depression 60 degrees east of Hualani which has some similarities to the Rongo depression. All of this going on in a 90 degree swath along the equator, with the remainder of the equatorial region looking much older and generally higher. Someday an interesting story ought to come out of this.

Direct link
http://www.nasa.gov/sites/default/files/thumbnails/image/pia19606_main_labeled.png

Posted by: bsharp Jul 30 2015, 09:45 AM

The topographic map doesn't justice imho to the rugged high terrain from SO image 34

http://photojournal.jpl.nasa.gov/catalog/PIA19603

This is between Yalode and Zadeni. Plenty of interesting peaks (shadows) and small craters


Posted by: Bill Harris Jul 30 2015, 11:55 AM

The ruggedness is exaggerated due to the low lighting angle.

What are the yellow arrows showing?

--Bill

Posted by: Charles Jul 30 2015, 01:04 PM

Does anyone have, or know a link to, a gif version of the rotating Ceres topographical globe animation? I have searched the internet without success.

Posted by: ZLD Jul 30 2015, 04:44 PM

Charles, are you wanting to pull from individual frames or do you want an actual gif? Also, in what resolution?

Posted by: Charles Jul 31 2015, 01:46 AM

QUOTE (ZLD @ Jul 30 2015, 12:44 PM) *
Charles, are you wanting to pull from individual frames or do you want an actual gif? Also, in what resolution?


A maximum resolution gif. Not the individual frames (I can pull those myself).

Posted by: dvandorn Jul 31 2015, 03:33 PM

Still no images posted that were taken after June 25th. Are we expecting newly-acquired images in the next week or two?

-the other Doug

Posted by: Herobrine Jul 31 2015, 05:49 PM

QUOTE (dvandorn @ Jul 31 2015, 10:33 AM) *
Still no images posted that were taken after June 25th. Are we expecting newly-acquired images in the next week or two?

I don't think Dawn has acquired any imagery since June 27. A few days later it started (or tried to, at least) its descent to HAMO, which is still in progress.
I feel like you might have already known that, though. If you're asking about imagery acquired June 26th and 27th, I have no idea.
Then again, I could also be completely wrong.

Posted by: nprev Jul 31 2015, 06:08 PM

According to the http://dawn.jpl.nasa.gov/news/news-detail.html?id=4659, it should be done thrusting in mid-August. Don't think that there will be any new imagery till at least then.

Posted by: dvandorn Aug 1 2015, 12:26 AM

I actually wasn't aware that there were no plans whatsoever to do any imaging during the transition to HAMO. Thanks for the reassurance, guys.

smile.gif

-the other Doug

Posted by: Bill Harris Aug 1 2015, 02:50 AM

I am working on a "Poster Session" presentation of the geomorphology of Ceres. This is a work-in-progress and new images are up at:

https://univ.smugmug.com/Dawn-Mission/Ceres/i-74b8Pd9/0/O/PIA19606_fig1--geomorph-v1.jpg

--Bill

Posted by: Habukaz Aug 1 2015, 01:05 PM

A new Dawn Journal is out: http://dawnblog.jpl.nasa.gov/2015/07/29/dawn-journal-july-29/

The next observing campaign will begin on 17 August.

Posted by: Bill Harris Aug 6 2015, 07:19 AM

And of course, imagery from the Survey Orbit continues to be posted. It is up to image "SO-41", with Zadini Crater.

http://photojournal.jpl.nasa.gov/catalog/PIA19614

--Bill

Posted by: ZLD Aug 6 2015, 01:56 PM

Looks like they just posted the a few of the CG slides from the presentation previously mentioned.

http://photojournal.jpl.nasa.gov/catalog/PIA19617

http://photojournal.jpl.nasa.gov/catalog/PIA19618

And an animation with the increased relief.
http://photojournal.jpl.nasa.gov/catalog/PIA19619

And lastly, a http://dawn.jpl.nasa.gov/news/news-detail.html?id=4677 on the Dawn website about the Occator image and animation. There is brief mention that the spots probably aren't ice and they may be salt related but otherwise, the piece is lacking in any new science details.

Posted by: Bill Harris Aug 6 2015, 02:33 PM

Along with SO-42. SO-43 SO-44 SO-45 SO-46 SO-47 SO-48 SO-49 SO-50 SO-51 SO-52 SO-53 now SO-54.

Posted by: Bill Harris Aug 17 2015, 06:52 PM

And the Dawn team has produced a cylindrical projection map with feature names:

http://photojournal.jpl.nasa.gov/catalog/PIA19625

and the mission is now in the HAMO phase. Wow.

--Bill

Posted by: kap Aug 20 2015, 04:48 AM

Does the equator look less cratered in the map because of the way the map is stretched, or is there actually a band across the equatorial area that has fewer craters than other areas?

Posted by: JohnVV Aug 20 2015, 05:45 AM

QUOTE (kap @ Aug 20 2015, 12:48 AM) *
Does the equator look less cratered in the map because of the way the map is stretched, or is there actually a band across the equatorial area that has fewer craters than other areas?


that looks to be caused by the highpass used to remove the middle frequency data and even the look out


Posted by: Malmer Aug 20 2015, 09:14 AM

The light is hitting the surface from zenith along the equator. that makes the craters much less visible. the further north/south you go the more relief is seen due to the sun angle.

here is a good reference on much of an effect the sun angle makes:
http://www.lroc.asu.edu/featured_sites/view_site/6

Posted by: Bill Harris Aug 20 2015, 12:56 PM

It's a byproduct of the distortion from the mapping projection and how the individual Dawn photos are selected and placed on the map. North of the equator shadows are on the south sides of the craters ("sun to the south") and the Sun become lower (shadows longer) towards the North polar area. And vice versa to the South. On or near the Equator the craters have little or no shadow and the Sun is near local "Noon". Consequently at or near the Equator the craters are de-emphasized and that band looks "flat and featureless".

In a manner of thinking, you have a sphere and you're trying to squish it onto a flat surface and have things on it look uniform-- a mapmaker's conundrum.

--Bill

Posted by: Sean Jul 28 2017, 02:13 PM

Click thru for a video showing Ceres relief...

https://flic.kr/p/WUiGF3

Posted by: Explorer1 Sep 27 2017, 06:31 PM

Happy 10th "launchiversary", Dawn! And to think it nearly didn't happened.

Looks like https://www.jpl.nasa.gov/news/news.php?feature=6955 long orbit doing cosmic ray measurements; not much in the way of new imagery these days.

And from the https://dawn.jpl.nasa.gov/mission/journal_09_27_17.html:

QUOTE
Before the end of the year, NASA will formulate another new set of objectives that will take it to the end of its operational life.

Hmm...

Posted by: monty python Sep 28 2017, 06:31 AM

I think the most amazing statistic from the Dawn journal is that the ion engines have imparted almost as much delta v as the the rocket that launched it!

Posted by: Explorer1 Oct 20 2017, 12:34 AM

http://www.jpl.nasa.gov/news/news.php?feature=6980
Trying to get as low as 200 km, through perihelion in 2018!

Posted by: TheAnt Oct 20 2017, 02:01 PM

Now there be a chance to get the data hoped from the lower orbit they decided against. -due to the faulty gyroscopes
So Dawn seem intent on doing the finals with the highest grade possible, with a hunt for water, vapor and better resolution images.

Posted by: Explorer1 Nov 1 2017, 01:56 PM

https://dawn.jpl.nasa.gov/mission/journal.html

Posted by: Nahúm Jan 19 2022, 08:36 PM

I don't know if this is the correct thread to post this. I'm currently recreating the topography and surface of Ceres through the highest resolution images taken by Dawn spacecraft in order to see different perspectives of this dwarf planet and maybe even creating a video as if we were orbiting Ceres. Attached I show two stills and here is my Flickr gallery that will be updated with more images as I have some time: https://www.flickr.com/photos/nchazarra/albums/72177720295995742





Posted by: john_s Jan 20 2022, 04:34 PM

Nice images! Keep them coming.

John

Posted by: Gsnorgathon Jan 24 2022, 03:03 AM

Seconded! Those are beautiful. Good work!

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