Dawn approaches Ceres, From opnav images to first orbit Options

[elakdawalla]

Whenever an interviewer asks me what mission I want to see next, I always say I want a Uranus orbiter. I want to see those moons up close, and study that ring system. Uranus needs more advocates.

Here's Ted's best work on Umbriel.

Morpheus, we know Ceres as a substantial amount of water; could even have an ocean. Water ice is not stable over the long term over most of its surface except near the poles.

[Toma B]

I made this gif animation by adding same frames in reverse order after the last frame in the original, so that Ceres rotates back and forth.
I find it much easier to spot different surface details this way.

Ceres rotating back and forth

[DrShank]

I made this gif animation by adding same frames in reverse order after the last frame in the original, so that Ceres rotates back and forth.
I find it much easier to spot different surface details this way.

Ceres rotating back and forth

I'm getting closer to believing those linear markings are real!

[antipode]

Whatever else resolves as we get closer, the theory that there would be no surface relief, just albedo differences, except at the poles because of Ceres' fairly high temperature seems to be dead.
Which presumably says something about the near surface composition not being generally icy (a really thick lag?).

P

[elakdawalla]

One possibility, which wasn't considered very likely, is that Ceres' crust is undifferentiated -- that the crust never heated enough to change from its primordial mix of ice and rock. The reason that this is unlikely is that if Ceres' interior has differentiated (and it almost certainly has), then you'd have the situation of a denser crust above a less dense icy mantle, which is unstable -- you'd expect the crust to founder into the mantle in that situation.

[Habukaz]

I find it much easier to spot different surface details this way.

It really is. Somebody should pass on a tip to the right people.

[Gerald]

The ideas of Phil and Toma B combined, stretched:

I've taken the average of two consecutive images to reduce image noise, but to avoid too much motion blur, allowing for some non-linear brightness stretching.
The stretching suggests higher specularity than real, but it hopefully shows features a bit more distinguished.
The apparent huge linear features make me think of Europa and large rift valleys on Earth, i.e. of tectonic features. Plate tectonics on a water basis instead of magma would be a thought I could get used to.

[ngunn]

if Ceres' interior has differentiated (and it almost certainly has)

I'm not up to speed on Ceres literature and I suspect a lot of other readers won't be. Can you remind us why the interior has almost certainly differentiated?

And while I'm here I'd like to add my thanks to Toma B. I agree with Habukaz - it really does help.

[Bjorn Jonsson]

Here is a stack of 9 images from the new January 26 images, corrected for Ceres' rotation. I used the last 9 images from the rotation movie. The image processing is very similar to what I did earlier with the Januar 13 images, a linear contrast stretch followed by an unsharp mask.



This is getting curiouser and curiouser. The southern hemisphere now looks even more interesting and I don't think albedo variations are a big factor there. I also notice hints of long linear features with roughly a NW-SE direction; I'm pretty sure they are real.

Whenever an interviewer asks me what mission I want to see next, I always say I want a Uranus orbiter. I want to see those moons up close, and study that ring system. Uranus needs more advocates.

Some time ago Uranus also became my absolute #1 target I'd like to see visited by a spacecraft mission (preferably an orbiter). It's well above my #2 target and I strongly agree that it needs more advocates.

[belleraphon1]

I am also seeing a lot of ridges.. maybe smoothed out due to warmer ice on Ceres surface?
And is the bright spot really that bright or is that an imaging artifact?

Also vote for Uranus mission!

Craig

[MarsInMyLifetime]

I don't know how it would be possible, but the visual impression I now get from the animations is of a rift valley separating the upper and lower hemispheres. Do any of the ice mantle scenarios make plate tectonics possible?

[belleraphon1]

Still fixated on the bright spot. Know the image processing to bring out other more subtle features would enhance it but. Really is bright compared to surroundings.

This I so cool fellow space friends. A big thanks to the DAWN team for providing the images so quickly! What a ride!

Craig

[dvandorn]

I absolutely agree with Bjorn and bellaraphon1 and MarsInMyLifetime, and take back some of my earlier comments about the "dark ribbon." It really looks like a very wide chasm system running from southeast to just south of due west, starting out the width of what looks like a large impact basin but stretching on, either the crater chain of all crater chains or an actual rift valley the likes of which dwarf even those on some of the Saturnian and Uraniun icy moons we've seen.

I'm almost brought to mind, looking at the terrain that begins to peek out from around the right horizon, of a massive disruption of the planet and re-assemblage of the chunks in somewhat random orientations. Ceres also looks a lot lumpier, i.e. non-spherical, and to a greater degree, than I would have thought.

But, again, we'll know better very, very soon.

-the other Doug

[dvandorn]

I gotta think the bright spot is an extremely fresh crater into an ice layer. Maybe not that old, either -- to escape the darkening effects of solar radiation and small impactors and be that relatively bright, we could be looking at a feature formed in the last few millennia, if not centuries.

The next question is whether or not the entire crust is basically ice, or something else with pockets or discontinuous layers of ice. That could explain why an impact in one location would be super-reflective while one only a few hundred km away is not.

-the other Doug

[antipode]

Does anyone have the feeling that within a few months there is going to be intense discussion here (and elsewhere!) about lander missions, and where to send them?

Seems to be indications of smaller bright spots. Could large impactors punch through several kilometres of dark lag to expose fresh ice, which then as the other Doug suggests, darkens over time?

P