Dawn's first orbit, including RC3, March 6, 2015- June 15, 2015 Options

[Phil Stooke]

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

Phil

[Gladstoner]

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



These were visible in earlier images:



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

[ZLD]

The green lines to the left and upper left of the 'Spot 5' area are definitely related to crater chains.


The lower right area could be rifts. I think it could be possible that the spidering lines near 'Spot 5' could be related in some way to whatever has gone on in that area.


Maybe the liquid ocean has most recently only existed under this section of the crust and each time a very large object impacts, it oscillates the water below cavitates, similar to if you strike the top of a beer bottle and it causes the bottom to blow out.

edit: terminology

[dvandorn]

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

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

[Bill Harris]

Please, continue to discuss and speculate...

[Ken2]

Maybe the liquid ocean has most recently only existed under this section of the crust and each time a very large object impacts, it oscillates the water below cavitates, similar to if you strike the top of a beer bottle and it causes the bottom to blow out[/url].

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

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

[Gladstoner]

Piazzi (contrast enhanced):



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

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

[TheAnt]

It look like volcano

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

[Ken2]

Those look a lot more like data dropouts or something else far more mundane than mini-moons or caves. Let's please not jump right to the most exciting (and improbable) conclusions here.

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

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

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

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

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

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

[elakdawalla]

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

[ngunn]

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

[Gladstoner]

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




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

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

----------

One more thing to mention....

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



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

[RotoSequence]

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




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

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

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

[alk3997]

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

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

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

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

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

Andy

[dvandorn]

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

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

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

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

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

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

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

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

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