Victoria's Innards, Your last chance to speculate before we really see it Options

[dvandorn]

So, here's a nice little short-term thread, to let people get on the record with their wild speculations as to what we'll see when we get "up close and personal" with Vickie.

Some have mentioned seeing gully-like features in the walls, in the MOC images. I'll take this moment to disagree -- it looks to me like the talus slope (which makes up most of the exposed interior of the crater, that and the dune field) is streaked all along the interior, and that some streaks swirl a bit as they approach the upper rim. I think what we're seeing here is mass-wasting down the slopes of a non-homogenous surface. While the bulk composition of the surface layer that's slowly falling into Vickie is probably all pretty similar, there are obviously pockets of lighter and darker materials. Those pockets are sliding down into the crater, leaving a striated look as light deposits slide down adjacent to darker ones.

At this point, the wind circulation system within the crater kicks in, modifying the light and dark streaks -- especially near the upper rim around the capes and down into the bays.

I think the gully-like feature leading down from Duck Bay is probably nothing more than a mass-wastage slide of dark material down into the crater that has been swirled up a bit near where the winds howl in through Duck Bay.

Let's see, what other potentially embarrasing predictions can I make? I think that while the dark spots on the far rim's cape structures aren't entrances into deep caves, I'd bet that some of them are shallow "alcove" caves. Places where softer rock have been windblown out of the near-vertical rock face, leaving dimple-caves in the rock.

While these would be great places to repel down into and set up a sleeping bag for the night (the cliffs keep the big predators away, after all... ), I doubt a MER would ever be able to make its way into one...

-the other Doug

[edstrick]

Than's for re-posting a pic of the double layered crater. I'd also posted a copy of a cropped image of that crater, maybe a year ago.

The essential point that these craters make is that the evaporite layers are separated by a very well defined layer of near-zero-strength material, probably of some significant thickness....I'd speculate quite a few meters, at least.

A small impact would crater the top layer, a bigger one would punch into the soft-stuff underneath and maybe have some disturbed rubble in a flattish bottom. A still bigger one punches a second crater in the deeper evaporite layer. In all likelyhood, the greater the thickness of the soft-stuff layer, the more defined and wider the bench is in the crater, though there will be some effect of crater size, too.

My impression is that the double-layer crater punched through the second evaporite layer (I'm SURE it's not a fresh lava flow or anything), into MORE soft-stuff underneath. That may well be what we're seeing at Victoria, but without a second evaporite layer in this region. Access to the soft-stuff layer may be pretty nearly impossible without a much more capable rover, and one equipped with some serious drilling or at least trenching capability.

[ngunn]

Access to the soft-stuff layer may be pretty nearly impossible without a much more capable rover, and one equipped with some serious drilling or at least trenching capability.

Not necessarily. Some of the 'soft stuff' would have been present in the ejecta. Of course it may subsequently have dried out and turned into something much like an evaporite, but I'm sure those clever geologists will be able to distinguish that from fragments of the original pre-impact evaporite layer.