Dawn's Survey Orbit at Ceres Options

[Paolo]

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

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

[antipode]

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

[TheAnt]

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. 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.

[alk3997]

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 I see Ceres as a body that was one-time active but has now cooled to a point that the surface is no longer active.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

[TheAnt]

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.

[alk3997]

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