Dawn's main antenna appears to be facing towards Earth right now with no gentle thrusting from the engines. I'm assuming more data is coming down...

BTW, I still see the northern hemisphere as brighter and less contracted than the southern hemisphere. The southern hemispehere seems to be more cratered and more excavated. But, I'm sure that will all change when we get better views.

Andy

Triple the resolution = one third speculation. Right!

Or is it, triple resolution = 3x speculation??

Maths was never my strong point!

I think it scales with the number of pixels. So triple the resolution means 9x the speculation!

Or to paraphrase Thomas Edison, it's 1% resolution and 99% speculation.

Meanwhile any times of todays imaging session RC1 and transmission available?

I'll drink to that!!

While eagerly awaiting the new images, here another processing of the Ceres OpNav3 sequence pia19179-16.gif, animated, and as tiles:

-- some remote similarity to the DLR version.

Regarding surface reflectance:
Approximately describing Ceres' surface reflectance needs far more sophistication than a matte Lambertian description of an ellipsoid.
A modified Lambertian description of an ellipsoid with a reflectance of about (cos phi) ^(0.7) for phi the angle between ellipsoid surface normal and Sun resulted in the best - but not in a good approximation - (for gamma = 2.2) thus far.

Those are incredible.

It is nice that we can finally start studying a large ellipsoid besides Iapetus. And we don't know very much about Iapetus!

WOW ! WOW ! WOW ! Thanks a lot Gerald !

Dawn is talking to the DSN now. So is Voyager 1, apparently.

http://eyes.nasa.gov/dsn/dsn.html

Looks like DAWN downlink is in progress as of 06:57am EDT.

http://eyes.nasa.gov/dsn/dsn.html

What a week ahead coming... DAWN Ceres RC1 and navcams from Rosetta 6 km 67P/CG flyby!

Craig

Sorry, I've been busy with Rhea that last couple of days. Here are those times

FC Stare at Ceres: Feb 12, 2015 07:22:00 - Feb 12, 2015 21:45:25 UTC
The HGA is pointed toward Earth between Feb 12, 2015 22:44:58 - Feb 13, 2015 17:44:22

So the spacecraft will begin its turn back toward its thrusting orientation in approximately 2 hours, 36 minutes from this post. Maybe images will show up today online, but my money is on Monday.

Yes most likely on Monday, the personell on the MaxPlanck institute should have left for the day at this hour now since it is Friday. But I could imagine one or two have hanged around for a first peek anyhow. That unless some of the NASA guys hijack an image or two (joking), I noted that Goldstone have taken over from Madrid for Dawn transmissions now.

Gerald, this is some really impressive processing you're doing. I hope you write-up your methodology some day, I would like to have an educated basis for doing something similar (though how many firsts like this will we have?). Really gives a sense that there has been some major resurfacing of the northern hemisphere extending well into the southern hemisphere, or alternatively that there is a remnant unsurfaced region in the southern hemisphere. I haven't had this much fun since Spirit & Opportunity landed

Craters are much more difficult to see in the northern hemisphere at this resolution due to the higher sun angle - I see no clear evidence of major resurfacing in the northern hemisphere. The biggest craters might be in the southern hemisphere though. What's happening will be revealed in the higher resolution images to come - waiting for the new RC1 images is remarkably difficult.

Resurfacing or not, you'll notice that the visible cratering is seriously uneven. Take a look at Gerald's thumbnail, for instance:



Notice how much farther up the apparent cratering goes on the right side than on the left. Keep your eye fixed at that area of Ceres' disk in the animation, and you can see how the "crater line" (inspired by the tree line..) goes drastically further down when Ceres rotates towards the right in the animation. Something appears to be different between at least parts of lower and upper Ceres, and illumination cannot explain all of it, as far as I can see (which is not to say that Ceres' upper hemisphere isn't also heavily cratered).


(in the same animation, it also looks like there's a massive chasm trailing to the left of the "twin crater" structure in the lower hemisphere - wonder if that's real..)

Exactly the point. There is a distinct line between the heavily cratered region at the bottom and the smoother terrain to the north -- seems to be a drop in the surface level (not steep enough to call a cliff) between the "southern highlands" and the "equatorial plains". True, we may be missing a heavily cratered region about the north pole due to orientation and lighting. A partial explanation may be that the topography is smoothed by viscous relaxation about the equatorial region, but the polar regions are cold enough to preserve the rougher topography -- but why the abrupt transition from one to the other?

Statistically, if other cratered bodies are anything to go by, there should not be a dichotomy in terms of what portions of Ceres were hit by large impactors and what portions were not. I think one thing that is fooling us right now is that the lower half of the disk we see is at a lower sun angle, and thus shows more relief. The northern half may be nearly as heavily cratered as the southern, just washed out due to more overhead lighting in these images.

Also, a lot of the "smoother" terrain, even in the southern portion of the images, looks a little to me like basin floors, which may well end up smoothing themselves out more than ringwalls thrown up by large impacts.

It's tremendously exciting to know the resolution will improve an awful lot over the next week or two!

-the other Doug

Fantastic work Gerald!

One has to say Ceres, at this point, looks a lot more like an Asteroid than a "Dwarf Planet".

Thanks for all your encouragements!

In this case I've averaged over all raw registered images, call this mean m. Call a raw registered image r. Calculate 3 * (r - 0.75 m).
The parameters 3 and 0.75 are specific to this sequence. I've not yet found a simulated model working better than the mean.
You may play with these parameters to enhance details on different regions of the surface.

When working on the reflectance, and on pinning down global parameters, I came across this approach. I've needed the average of all linearized images to compare it with simulated reflectance models. So the above processing has been serendipitous near a presumed way to a topographic map / DEM.
Currently I'm working on estimators for the reflectance functions for small areas on the surface, kind of data reduction, intended to be usable to infere inclination and albedo data. The surface seems to be very rough after a first analysis, such that I expect a reflectance down to pixel scale not easily covered by the Phong model. This needs some theoretical preparation. I'll try to explain the role of the estimators later, together with maps of some of them, provided the approach works.

There could be phase/shadowing effects. Patience, all will be revealed soon.

a new paper in open access that will probably be soon outdated (still, some interesting ideas...)
Short-term variability on the surface of (1) Ceres

I don't think either that such a dichotomy would make much sense (although e.g. Enceladus does not seem that terribly far away from having one (in terms of being cratered); and it does have one when comparing the poles specifically).

But I don't see how the sun angle could explain how the apparent cratering changes with latitude and longitude both, like it does in the images. There really does appear to be some sort of transition(s) going on near the equator, indeed perhaps into basins. It might be that there are just small strips of terrain that have a slightly different topography (and that the north and south are mainly the same), but I feel confident that either the 12 Feb or 19 Feb images will vindicate my view that there is something (potentially quite trivial) going on there.

Indeed, there is just 5 days until the 221 pixel global images of 19 Februrary are taken; that date should be marked as a milestone for the exploration of the solar system.

What are you expecting a dwarf planet to look like? Ceres is the first dwarf planet that has been encountered by humanity since the definition was termed by the IAU.

What I guess I would have expected of a dwarf planet to look like would be, um, well -- a little more well-rounded. The overall impression I get from the opnavs is of a lumpy body that is out-of-round in significant places.

It doesn't give the same impression of smooth roundness that, say, Enceladus does (as a body of very similar size). I suppose I was expecting something a little more like that. Instead, it seems to have corners and gouges and big uplifted sections and long connected depressions. Complex and fascinating, but less overall rounded than I expected.

I think Ceres comes across as pretty spherical in the raw frames. I suspect that image processing is exaggerating and/or creating unevenness.

Pretty sure we're looking at significant compositional (as well as situational) differences between Ceres & Enceladus here that could explain this. Not only is the latter subject to some degree of tidally-induced internal heating, it's also predominantly icy.

By contrast, Ceres probably doesn't have any sort of significant internal energy source left & it's much rockier. Big impacts therefore tend to persist a LOT longer, so, yeah, I think it's gonna be quite lumpy-looking.

Ceres has about twice the radius of Enceladus (see diagram). I think it's probably Enceladus that's anomalous in its size class for being so round.

As a layman, a Planet, whether "Dwarf" or otherwise, should be spherical and have surface terrain elevations small in comparison to the radius of the body. In other words, appear from such a distance, to be fairly smooth. It is clear that some serious chunks have been taken out of Ceres. It is not of sufficient size to sustain a basically flat terrain within it's orbital environment. I realise this is a definition requiring nearer object observation than available from Earth, but to categorise an object in space knowing next to nothing of its physical appearance seems presumptuous at best. That argument is for another place.

My comment was more a general descriptive observation of what we could see up until now, as opposed to more problematic and possibly, ill advised, speculation as to what the various features might be.

I was going to post something like that but you beat me. Good job.

Most objects about Ceres size are heavily cratered and without any neighbors Ceres can't resurface without a giant impact. And if there isn't a trick of the light and Ceres dichotomy is real, than that just reminds me of Mars, whose hemispheres are significantly from each other for reasons not yet well understood. And I think we can all agree that Mars is unambiguously a planet.

Hey, guys -- as with Sherbert, I was just giving my impression of what we're seeing from the distant images. Ceres does look lumpier than I expected from this distance, and I'm not the first here who has made that observation. Obviously, as distance decreases, we will know more and more of the truth of the matter. And also, as has been stated here, if we couldn't speculate at this point, it wouldn't be any fun...

As for Enceladus, I was looking with tired eyes, I guess -- and relying on Wikipedia being consistent in how it presents information, which is always dangerous. Before I wrote that, last night, I checked and Wikipedia said that each was about 500 km wide -- except that, upon a further look this morning, it was giving a diameter of Enceladus and a radius of Ceres. And, stupid me, I read them as being the same measurement. But, ultimately, my bad.

-the other Doug

I thought Vesta looked oddly lumpy before we got closer, so I'm definitely reserving judgement on that for later.

Even poor lumpy Vesta is described as a proto-planet by the Dawn mission. Compared to asteroids seen up close by s/c, Ceres does not look like them. Can't wait for the next 2 sets of images, the added detail will help us see past the mirage created by lighting effects on not enough pixels.

Yes, the danger of speculating. For instance in the attached 2/04/15 photo, Ceres looks much like a hot air balloon where the bottom portion has had a small amount of air let out. The crater at the southern pole helps with the visual. It just *seems* that the southern hemisphere of Ceres is less round than the northern hemisphere. Whether that is real will be answered in the next few weeks.

I've also noticed that a lot of the enhancements are making the brightness of Ceres appear more uniform than the original non-enhanced images. That difference in brightness may be due to the viewing angle or may be because of surface differences. It may not even be real. But, again, a few more weeks and that question should be answered and a whole lot more questions will need to be answered.

The fun of arm-chair exploration...

Andy

Here a first, very tentative version of a map towards (east-west) inclination data:
Click to view attachment

It's based on a map of estimators E[X] of the expected frame number of the light curve (as function of the frame number) for each 0.25°x0.25° longitude/latitude square, the light curve interpreted as a probability density function.
The goal is to find out the phase shift of the light curve for each lon/lat position, since the phase shift should be correlated to the east/west inclination.
There are still several issues. I've applied a hipass filter and a stretch to the raw estimator map to compensate for systematic errors in the model.
Be carefull with interpretations, since processing artifacts are likely.

Taking the issues into account, there appears to remain a diagonal chain of at least four craters from center north, eastward.
This may indicate, that the northern hemisphere is also heavily cratered. But thus far I don't see features similar to the pair of huge craters south of the equator.

I think I'm now near the limits of what I can squeeze out of the OpNav3 sequence with reasonable effort.
Next processing attempts with the new sequence.

I hope it doesn't come across as patronizing to point out that what we have thought should be true has, so many times in this golden age of planetary exploration, been completely invalidated by what is actually out there. Little Miranda, for instance, has no business being anything other than a cratered lump, yet there those amazing coronae are. In a few weeks we'll doubtless have a clearer idea of what to argue about, but in the meantime I'm just going to enjoy the front-row seats to unfolding history.

Here's what I'm expecting: a unique body with some similarities to other objects of the same size, but also many important differences!
Maybe that's vague enough?
We'll go through the same speculation roulette wheel with Pluto soon enough; might as well get some practice in.

Am I missing something or are we not waiting for the RC1 images? Or can I stop checking this site every four and a half minutes. The waiting is tortuous!

Yep; all waiting. Open tab on the Dawn twitter page.....

The previous release (as well as at least one more) was at around 14-15 UTC. That's more than two hours ago now. I don't think there has been given any guarantee that the images will be released today, but the day is still young in the right time zones. *crosses fingers*

Federal holiday in the U.S. today. I wouldn't expect any release today.

Andy

Ouch. I actually have the public holidays and the like of many countries on my calender, but I never bother reading them.

I've waited for 45 years to see Ceres up-close... I can wait a few days more...

Plan is for a tuesday release but that might be held up a day or two. the process is rather involved, at multiple levels of the project and NASA HQ to make sure that the images released are properly processed annotated and described. all rather complex, but the folks who help us do our job need to do theirs!

I split the posts about airbrushed maps into a dedicated thread to save them getting lost here.

http://www.unmannedspaceflight.com/index.php?showtopic=7974

Hello folks, it has been a while since I poked my nose in for a blether.

Looking forward to a new release of Ceres approach images.

While pondering the white splotch, the thought of an icy moon debris fragment impact went through my mind.

Like a Europaberg impact.

A cryovolcano as previously head scratched would be nicer though I think.

They're out.

http://www.jpl.nasa.gov/news/news.php?feature=4485



http://www.mps.mpg.de/3923141/PM_2015_02_1...d_Strahlenkranz

The elongated white blob in the upper centre of the second image here seems to have legs growing out if it...

A miniature planet : Ceres is the world of Saint-Exupery's "Little Prince" !

Click to view attachment

Definitely looks more spherical in the new images. Perhaps the lumpy appearance before was due to shadowing artifacts afterall?

Also looks heavily cratered.