LAMO 34

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L29-L34

Dantu Crater mosaic:

(PIA20193, PIA20300, PIA20303)

The bright streaks on the crater walls, landslides of bright material or salt deposits left behind by flows of liquid?

LAMO 35

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a few renders of LAMO-35 PIA20389




in particular is the "wasting" area at the top of the image

My guess is that they are scattered/isolated deposits (veins?) of salt that were exposed by mass wasting of the crater wall.

Considering the extensive emplacement of impact debris mantling units all over Ceres, I would guess the top 500 to 1,000 meters of the surface is a battered, crushed layer of poorly mixed, brecciated debris. There are quite likely a huge number of salt and salty ice deposits embedded within this debris layer.

When craters are made in this kind of surface, these pockets of high-albedo salt (or salty ice) become exposed; more are exposed as mass wasting deflates large crater walls. Thus, the occasional white spots and streaks seen in crater walls.

Now, this is completely separate from directly-emplaced cryovolcanic deposits, like what we appear to see in Occator. Those (and there are quite a fewer number of them than the smaller white spots) seem to be examples of deeper material moving volcanically up to the surface from deeper layers of soft salty ice (or even liquid salty water). That's a different emplacement mechanism from most of the small bright spots we see on crater walls, I think.

Think of it this way -- take a surface composed mostly of black sand, and randomly embed a bunch of white pebbles in it. Then hit it with an impact. Your resulting crater will show mostly black sand walls, but every once in a while a white pebble will poke out through the major black sand matrix of the unit. And as crater walls recede due to mass wasting, new white pebbles are exposed. Now, just replace the black sand with the general dark material of Ceres' surface and the white pebbles with concentrations of salt and/or salty ice, and you have a model for what may well be happening on Ceres.

I think the first paragraph quoted describes very well the likely formation process for white spots. So why invoke a different process for Occator? Any 'activity' there could just be the mass wasting of freshly exposed ices you already mentioned.

I can't recall what conference was going on last week but I definitely saw some graphics pop up on Twitter that showed that the Dawn team is pursuing cryovolcanic processes for Occator. There was a nice side cut-away image as well. I'll try to find it and post if do. The possibility has been floated in several other recent talks as well.

If there are deposits of white salty material embedded at random locations in the regolith, then they should be uncovered more frequently around the rims of the craters than in the centers, should they not? Cryovolcanic scenarios do seem to fit a bit better better with the "bullseye" pattern we see in places like Occator.

LAMO 36

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Recent LAMO imagery and a current LAMO Index map:

https://univ.smugmug.com/Dawn-Mission/Ceres-LAMO-Images/

--Bill

LAMO 37

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LAMO -36 (PIA20390)

is a very low angle of illumination , the process i use dose not do a great job on these images
but a few areas look good

LAMO 38

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LAMO 39

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