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

Cough.. cough...



I have to admit though, the image above is strictly an artistic representation, made in about 15 minute's time. I had no time to actually observe the high-res MSSS image to make it accurate enough...

But, I think you're right, Doug. The sandy slope appears to extend all the way up to the bays, and some of the outcrops stick out from that slope. Some of the sand streaks are dark, some are light, and I assume that is due to the different compositions of the rock above where it came from. We definitely won't be seeing the outcrops (cliffs) extending all the way to the bottom of the crater, and the current pancam views pretty much show about 80% of the cliffs already. The rest is just sand.

Amazing how many people elsewhere have fallen for it - hook, line and sinker

Doug

Heh, I know the MC forum had a few people feverishly trying to find it at exploratorium, but if you know other places also please let me know where

http://www.habitablezone.com/space/messages/439873.html

Doug

Actually, the graphic will not be that far from reality, I suspect. The sandy slopes below the main walls of Victoria, like at Endurance, are rather featureless till you hit the central dune/drift mass. THAT is gonna be really spectcular, with textures and colors as we saw at Endurance in a small scale and on el Dorado as Spirit stuck it's "toes" in the "water" and took a look.

Pando's visualization is very close to what we will see when Oppy gets to Victoria's rim. There will be that wonderful bluff (Burns Cliff x1000), talus and dunefield. Rather like the Mesas in the American desert southwest. I rather doubt we'll see in-place bedrock below the bluff, which is why it is important to examine the non-evaporite rocks on the ejecta apron; these should/may be from the lower units in the column.

"Buck Galaxy"? Not another nom-de-modem of Pando?

--Bill

I don't fully agree. I also think that Pando's not far from reality but what I expect to be different are the details. Some of us suggest that there's a field of boulders, some rocks felt down and stay hanging before the dune field, and some others observed/speculations. If true, that could make a big difference in the way Vicky is gona look. As I said in another post, Nature have most imagination than ourself. That's may be why we want to explore.

One of the tricks will be figuring out Vicky's age. If, as many suspect, there was a lot of groundwater (ground ice) still in the soil when Vicky formed, there would possibly have been gullies formed down the sides of the original Victoria crater, just as we've seen gullies in other Martian features in many places. However, the mass wastage process has probably destroyed them all, and in fact has probably also covered any other original evidence of age, with the possible exception of the upper portions of the cliffs that haven't yet collapsed.

I think we can forget about RATting any cliffs. If we can identify any debris as being specific to a particular layer or even a particular spot on a particular cliff, that's probably as good as it gets. But the cliffs will be unapproachable, just as Burns cliff was in Endurance.

There will be dimple caves; that seems to be part of the mass wastage process, since the lower layers seem more susceptible to wind erosion than the upper layers. Sitting under an overhang would definitely be high-risk, although probably not in the time-frame of Oppy's visit.

Vicky is not an exhumed crater. I went looking for photos of other exhumed craters on Mars; there's just no ressemblance.

I'm concerned that Vicky's interior may be mostly unnavigable, due to tallus. Check out this photo of tallus from Mt. Wilson: http://shallowsky.com/images/geology/wilson-landslide.jpg Not that this is entirely bad; we haven't really seen erosion on this scale anywhere along Oppy's or Sprit's paths.

When we get the ability to look closely at the exposed strata, we will see that for the 30 to 40 meters that Victoria lets us see, it is Epsom salts all the way down, with some variation in the content as we go down. At the lowest level we'll see, the blueberries will be 15 millimeters in diameter.

dvandorn asked for wild speculations. I thought I'd revive one from a few weeks ago. Someone speculated a while back that the margins of the bays were the original margins of the crater. For that to be the case, the capes, and associated overhangs would have to be accretionary features that formed after the impact. Can anyone come up with a scenario, which miight support that idea?

All I can think of would be drift sediments spilling over the sides of the crater and becoming indurated by some unknown process.

You asked for wild a crazy .....

I think we will see evidence of vertical shearing of strata in the promontories consistent with undermining of the original crater rim at some depth now concealed below talus and inblown sand.

One of the puzzles to me is the scalloped rim of Victoria, which is unique but not too unusual. Looking at Slinted's meridiani_themis image, we see several degraded craters to the northeast and southeast that have a very soft rounded rim and a central dunefield and one crater with a hint of scallops. Only one, Victoria, has the pronounced scallops but I interpret the soft rims on the other craters as a scalloped rim in a late stage of development. And you recall that the Payson outcrop area and the so-called "Payson Promontory" may be a highly eroded bay-and-cape at Erebus crater. And we may have seen immature forms of the scallops at Endurance crater with some of the cliffs standing out from the receding pre-bay areas. I'm wondering "why?", and presume that this relates to the mechanical and structural properties of the evaporite unit in this locale as well as Martian weathering processes.

As an aside, the next Rover mission ought to start in Big Crater and work it's way NW toward Victoria; that would be a wonderful traverse.

--Bill

Your thoughts on the scenario I suggested in post 315 of the 'Final Approach' thread would be most appreciated. If I'm talking rubbish I'd rather be told so at an early stage! (and in a nice friendly place like this)

Kind of bummed about the extensive dust obscuration of the slopes... ...sure hope that there's a few clean patches here and there, anyhow.

Diane,
Not at all, not all all! I've got another exemple. You know I'm not a geologist but I've got some experience hiking the mountains and I want to share this one. My wildess dream will be to actualy Rat the cliffs and I believe it IS possible because I hope we can get to the "horizontal feature".
Let me show you what I mean. This horizontal feature is still very far and I guess it could look a little bit like this (I'm talking of the upper part since we know that the lower is different from this) :
Click to view attachment

Pretty steep eh? Now, look how it looks like when you're actualy there :
Click to view attachment

Convinced ?
I'll dedicate my time looking pictures to find out a place where Oppy will have a chance to get there.
That's the big difference as compared to Endurance. The feature could be a kind of terrace. They call this "Faja" in Spain. These pictures come (once again) from el "Parque National de Ordessa y del Monte Perdido" and it's called "Faja de las Flores".
What about 2007 UMSF meeting there?

Now that's the kind of meeting I've been thinking about to be honest. I'd just love a gathering of UMSF'ers in a rough mountain area combined with an overnight stay at high altitude to look at the sky at night.

It's maybe not that realistic but I'd LOVE it..

Nico

Uh, beer is out of the question then...

Practical limitations of site selection notwithstanding, you have an entire planet to explore and you would go back to what is essentially the same neighbourhood? I don't want to sound like I'm bored with this area, but I certainly hope the next rover goes somewhere drastically different from either MER site.

Brian

I'd like to let you know that I NEVER get hiking with friends without bringing a bottle(s) of wine

Uh, no-go..must have a few beers along. a few

Nico

Singing fish indeed, I got vertigo just looking at the pics at full scale. Then realising you'd walked along that narrow sloping scree-covered ledge to take the second picture... *shudder* You were roped up for that, right? No, wait, I don't want to know!!

Anyway, I can't imagine Oppy could navigate such a ledge, even if VC did have such a feature.

(Edit, having read the next few posts) You did that whilst drinking?? Now I really am going to be ill!

You know what rovers drivers are able to do, don't you?
About myself, I just don't drink when I go there

Can we please have the barbecue at a safer spot?

OTOH, this is the only site on the entire planet where we have spend 2 years studying several meters of the sedimentary record and continuing the traverse downhill and down-section makes perfect sense.

--Bill

I won't dare step into a geologist's boots, but here's an image which shows that the scalloping of VC is not unique:
Click to view attachment
Unfortunately I do not know what the source is, only that I believe it came from this forum a couple of years ago and I recall it was located in the vicinity of Meridiani.

Hopefully this "alternate Vicky" could inspire the geo-minded to understand the processes involved.

As far as what the interior of Victoria will look like, I think Pando has nailed pretty well what we might expect to see with a low-res navcam view. The response of the navcams matches fairly well that of the MOC I believe, which explains why we can match features on the far rim so well between orbital and navcam. I expect the same for the interior.

Even the L7's won't give much of an improvement on our current L2 view of the far rim. What is very hard to predict is what the closeups of the inside rim will look like. I can only give the interior of Endurance as a prototype, but of course VC will be much more dramatic.

So Pando, could you give us a nice simulated full-resolution L7 view from Cabo Verde looking across Duck Bay to Cabo Frio?

Not convinced, but always open-minded. There's no way to know until we're there. I do worry about Oppy's footing. (Perhaps not quite the right word.... Maybe what Oppy needs is monster truck tires.)

Anyway, I'll look forward to your expeditionary reports! This forum is so addictive because of the wealth of knowledge and viewpoints that everyone brings.

Stay in the Serengeti for a month, then venture off. If you go back later on, during the wet season, and things will look a lot different.
Or look at Halley's Comet. Quite a number of probes from several countries flew past it. Different equipment can get different or better data.


But at this point, I'd be happy to see MSL just land somewhere safe and interesting.
Though it might be cool to go back to see Opportunity or Spirit in their final resting places, camouflaged with a layering of dust, permanent monuments to their achievements.

I would say Mud Flap Gal & Mysetery Man will be inside of Victoria but I think it will look like Endurance but much larger

Click to view attachment

> won't dare step into a geologist's boots, but here's an image which shows that the scalloping of VC is not unique:

Ah, that crater has a form uniquely different than Victoria's, and since you found another scalloped crater rim, it is not unusual. Ergo, unique but not too unusual.

--Bill

Hmm, that reminds me... I posted (as 'youremi') 2-1/2 years ago (exactly!!) at the other forum about some craters I've found in Meridiani here:
http://www.marsroverblog.com/discuss-11596...ally-weird.html

There are links to MSSS for them as well, including this bad boy:

http://marsoweb.nas.nasa.gov/landingsites/...02-01143_05.jpg

It appears that larger impacts are punching thru some sort of evaporite layer which ends at some discrete depth. Interesting... Then again, it could be an illusion since the sand starts getting accumulated at the bottom, and we may be seeing the borderline where the sandy slope is starting, which is presumably not a steep as the rocky inner slope?? If I remember right, I think these craters are some 20+ km south-east from Oppy's current location.

Thanks, Pando. Judging from the filename and creation date it was probably in your post that I found that image.

LoL (haven't heard that one mentioned since the good ol' BBS days...!)
No, thankfully not... This guy apparently hotlinked an attachment from this board and... well... Doug wouldn't like it too much

Uh, yes, your post "over there" a couple of years ago. The place does have a unique character, no?

Your examples are why my hope and dream is that the mission would be able to continue the traverse down-section. This locale does have a wonderfully complex stratigraphy.

--Bill

Thanks for posting that Pando. Post 44 inside your first link describes exactly the mechanism I have been suggesting for the formation of Victoria. That's reassuring, but it's still only in blogland. Does anyone know if it has appeared, even as a possibility, in the scientific literature?

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.

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.

I think most of the local soft-stuff has blown away with most of the ejecta layer (except for blueberries), and been replaced with the basaltic sand that I think has actually drifted across Meridiani from outside sources. A petrology lab would have lots of fun with samples, and MSL might do a pretty good job, but MER gets only hand-lens black and white info on the fine bits samples are made of, the other instruments just average large (square centimeters) areas.

The latest images of Victoria appear to show that most of the bays are covered by drift that seems to be continuous with the sediments in the bottom of the crater. Do you think the sediments in the bays are drifting in from the plains surrounding the crater or is some of the sediment in the bays being transported up and out of the crater through the bays?

A secondary question: if there is a layer of poorly consolidated sediment beneath the rim, then how much of the sediment in the floor of the crater is from the crater itself?

I'd guess the inward and outward flows of drift material are about equal, or else it would either fill up or empty out completely. Of course that says nothing at all about what these rates actually are, or how they compare with the age of Victoria, which is what we'd need to know to answer your secondary question.

I'm confused. Are we looking over the near rim and seeing the far rim? It looks so close

http://qt.exploratorium.edu/mars/opportuni...CNP0666L0M1.JPG

You have it right. I know it's confusing, but basically, the view is quite similar to Endurance, just scaled up

Dogu

Dogu?

Has anyone considered the possibility that Victoria could be a caldera rather than a crater? Seems a bit wild I'm sure but this is a very unusual crater. It is highly eroded yet still has a distinct bowl shape. I find it so bizarre. I wish some genius would explain its morphology. The degree of erosion is incredible given the fact the form of the crater is well preserved. It must be very very soft stuff those blueberries are in, evaporite or whatever because the wimpy Martian wind can blow it away.

It's easy to underestimate the size of Victoria by looking at the images taken by Opportunity so far. It's much bigger than it seems, but not much deeper. Look at the photographs from space - there are wide ledges along the rim. They look very steep in the MER images.
I believe the diameter to depth ratio for rocky meteorites is 10:1. If Victoria is 800m wide, its initial depth must have been 80m, and now it's 40 or so. That's a lot of stuff! The bigger the crater, the more is the ratio of the volume displaced by the impact to the volume displaced by erosion in the given time.

>explain its morphology

It's a crater.

--Bill

Ah, right. Now where's that smarta$$ smiley when you need it?

Bill, thanks for posting the Meteor crater formation. That looks like a good starting point for Victoria.

I know we don't have a realistic estimate for Victoria's age yet (other than "old"), but I want to keep in mind that Mars' atmosphere might well have been more substantial, enough to have more effect on wind-driven erosion of the cliff walls. Do we have any useful estimates of Martian atmospheric density over the life of the planet?

Boundary between original surface and ejacta blanket? I see some blocks that appear to have layering at an angle though it is difficult to tell with the jpeg artifacts. Material below line reminds me of top, evaporite, layer in Endurance
Click to view attachment