For those who haven't noticed yet, there is a new update from Steve! Oppy will probably start moving towards St. Mary early next week.

An extract from the same status report:

Once we do start moving Opportunity again -- probably early next week -- our direction will be toward the east and north... clockwise around the crater. We haven't decided how far we'll go in that direction, but it seems clear that some of the most intriguing geology we can see from the rim is to be found that way. So that's where we're headed for now. The next big topographic feature in that direction is a tall promontory that's one of the highest spots on the rim. We've named it Cape St. Mary.

my version of Cape St Mary


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It looks like we may finally set wheels on the beacon!

Any speculation on what this "intriguing geology" might be? The St Mary cliffs? It will be difficult to get a view of the lower cliffs from the cape. Regardless, we should finally get views of the northwest rim of Victoria that has been blocked until now.

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Perhaps those sculpted cliffs in the northeast rim which seem to expose quite a good cross section "along strike" of the column; maybe the rockfall. There are the blue-grey (not sure what their true colour is) plumes of dust blown out of the crater by the wind. There is the scarp visible above and to the right of the CSM promontory marked in the above. A look at a sheer face like that could show considerable detail. Maybe they think the prospect of getting into the crater is better that way.

Isn't the question mark ( ? ) on MarkL's photomap one of those big boulders we see on the Pancams from current location? If so, the rock would need to be perched beside a crater also, from the lie of the shadows.

The "big boulders" you're talking about are probably the ones much closer to us, on Cape St Mary (actually they're hardly boulders - the largest are just 10-15 cm or so - see my post in the stratigraphy thread).

This strikes me as quite an odd thing to say, as at this point the beacon hides a lot of the clockwise rim. It's no surprise that CStM is the next target , but I would have reserved a decision on clockwise vs anticlockwise till we got there and could actually see more of the the north rim. Then again they do have the HiRise.

A 360 from the beacon please Jim/Steve.

James

For what my opinion is worth, it appears to me that the freakin geology is utterly amazing in all directions around this crater. So, they could hardly make a bad decision in that regard. But, they do have to make that decision, and they must consider non-geological things, like solar illuminance, potential winds, entry points, and probably quite a few things I am unaware of. Although it probably doesn't really matter which direction they choose, the clockwise direction does seem to offer some advantages. I had previously mentioned that the higher elevations near the beacon might reveal the highest stratigraphy Opportunity is likely to see, and that is one good reason for that direction.

It seems that several of the capes on the north side are less broken up than the others, so they might display a more intact section to us. It is also the shortest direction to the east side, where some of the deepest exposed bedrock seems to be.

In the final analysis, it really doesn't matter which direction is chosen. It will be a hoot, regardless...

You're right, FredK, the "boulder" I had in mind is one of those you mention and doesn't appear to have a crater beside it anyway.

Bill, I'm trying to envisage the erosional consequeneces of "aeons of wind" in a very low density atmosphere and it's difficult. But assuming the embedded evaporite blocks in the bays are harder than the matrix material which surrounds them, I don't see how the wind could produce what we see - a flat surface in which both blocks and matrix are ground down equally. Wouldn't we end up with mini-Ayers Rock type wind sculpted lumps where the harder blocks are, sort of like the ventifact on the edge of Bonneville over in Gusev?

Some of the bays have the look of a miniature incipient cirque (or "corrie" in my local parlance), with a glacially planed-down back-wall. Breccias get ground flat by ice, hard and soft components equally. Dare I suggest micro-glaciation in these bay headwalls in some far-off different climactic era?

Kenny

Tom, throw a rock in any direction here and you'll hit amazing geology. I imagine that we would start at the north Capes since they are topographically higher and we'll see the highest part of the section. And conversely, the southern Capes are topographically lower and can expose the lowest part of the section. And inbetween, what sort of lateral changes in the section are present? Oooh, so much to see and so little time...

Kenny, I compare the aeolian erosion to sandblasting with baking soda or ground-up walnut shells instead of sand. A very gentle process small particles moving at high speed, abrading the soft evaporitic sandstone over a very long period of time. By it's nature the process tends to "plane off" the surface. Look at the spots we've see here at Meridiani where the evaporitic sandstone leaves a 'tail' or a 'stalk' downwind of a blueberry. And also, as you note, this has been seen over at Gusev.

I discount glaciation right off. You need a mountain elevation for a lot of snow to collect and temperatures warm enough for the ice to flow and bedrock that is not water-soluble. I have a hard time visualizing those conditions here.

--Bill

I agree that there is nothing that looks like glacial erosion here. However I am uncertain whether corrie erosion really requires wet-based ice. It seems to me that cirques/corries are mostly shaped by gravity sliding and plucking at the bergschrund which would probably work even with the ice frozen to the substrate.

tty

Fabulous new images coming down. Here's a very false colour of the foot of Cape St Mary cliff:
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Notice the colour fringing on the edge of the shadow of the high part of the cliff - this is because the cliff is so high that the shadow moved substantially between colour frames.

I wonder how much the decision to continue clockwise was affected by the MRO image. Maybe it was almost entirely based on that image?

fredk
Thanks for posting that image. It shows just what I was hoping to see: large scale cross beds.

Also a beautiful rolling boulder trail in the new images:
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First attempt to stitch only some of them (with sharpening)...
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I know upper/right portion do not match very well, seem taken with different filter set (perhaps different local time).
Comon guys, competition started!

Me, too. I guess it was to be expected, but those beds now look like a pretty good correlation to those we saw at the base of Cabo Verde.

I managed to get a 4x2 panoram stitched. I'm not as skilled as others in adjusting colors, but here it is, anyway.
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That's actually kind of a cool effect...

[quote name='Bill Harris' date='Nov 4 2006, 11:35 AM' post='74396']
"I imagine that we would start at the north Capes since they are topographically higher and we'll see the highest part of the section. And conversely, the southern Capes are topographically lower and can expose the lowest part of the section. And inbetween, what sort of lateral changes in the section are present?"


Can you, or someone, estimate the distance in meters between the highest and lowest parts of the section, top of north Cape to top of southern Capes?

Stevan Davies

Actually the rolling boulder trail can be seen in another frame. Here's a lame splice showing its full length:
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Interesting features on St Mary cliff: they appear to be narrow verticalish ridges protruding away from the cliff, rather than cracks set into the cliff, as if they were caused by cracks that were filled with some material that's harder than the surrounding rock. The arrows point to the best examples I found:
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I don't think we have seen any evidence of recent movement on Mars before this, except for dust devils and the rovers themselves. Is that correct? Of course, recent is a relative term.... I wonder how long ago that rock rolled down the slope.

Scott

Thanks, Fred, et al-- those are indeed wondrous images. And we've barely started here! I'm sure we'll run past our quota of superlatives soon.

One other confirmed recent movement event was that dust slip at Overgaard, and some dust blowing in the wheel tracks. These bouncing boulders may tell us a lot about the mechanical characteristics of the sand.

Off to Exploratorium...

--Bill

Hehe, thanks. I'll take whatever compliments I can get, but I just wanted to see part of the view for another project, regardless of the vignetting, or whatever that was. Someone here will eventually correct those defects. My devignetting software didn't want to work with the color composites, and I didn't have time to do all the filters and make new false color images. My wife was waving that Mars Widow card at me, and I had to get back to painting the house.

Bill: How's your retirement going?

Well the Cape Verde pan is a bit of a mess at the moment, but since it's a competition, here's my entry.



James

great work, James! (and yes, pan is a bit of a mess at the moment...).
Below I made a manual stitch of L2 images only, to better show dunes and rim features:

Victoria has varicose veins!

Brian

Heh heh... well I can't really compete, and I shouldn't be taking time to do this anyway, but here's my technicolor perspective rendering of Cabo Verde at the moment:



A different view:

but, where is the boulder? There is no obvious candidate at the end of the trail.

The "end of the trail" is on the right side of the image, and the boulder is obvious. This is a view looking downslope.

Bill, on further thought I agree. The uniformly smoothed down slopes of mega-breccia/conglomerate (consolidated impact ejecta) in the bay are actually very similar to some of the surfaces we saw on the rim of Beagle. I initially thought that the scouring wind would preferentially remove the matrix and exhume the embedded blocks, but I suppose both could be of similar resistance and both plane away at the same rate. Plus, the ventifact at Bonneville was fine-grained basalt as I recall and so undoubtedly harder than our evaporite here, hence not a good comparator.

Lots more to think about. Kenny

The open question is why are we observing selective erosion? Are the capes particularly resistant to the scouring dust grains? An inspection of their "gross" mechanical characteristics (basically a guess on my part) seems to show they are also built of very soft and crumbly material. Almost like a hardened slurry or mud which has conglomerated with the ejecta rubble. There are plenty of little vertical vents or cracks in the matrix/conglomerate visible at the exposed edge of CSM as well which lead me to think that a couple of swift kicks would dislodge quite a bit of stuff from the edge. If only Opportunity had a hammer ...

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I don't know what it is Kenny. It looks a lot like a small crater, but when you look at a zoomed version (contrast bumped up a bit) it is more enigmatic. It looks like a six-pointed star inside a crater. Almost a mini Victoria. It struck me as a bit unusual and maybe worth a look later on. It is only a couple of metres across though.

Here is an interesting L257 Pancam from to-Sol's images. There is some drifting blue basaltic sand (or blueberries?), as well as sapping of the sand into fractures. I've not been able to determine the context of this location, but it seems to be towards the interior of the crater and not in the adjacent bay.

--Bill

It's part of Duck Bay.

Edit: Just left of centre in this navcam

Bill: I saw them. They are really surprising in 3D. Don't miss that.

So what sort of Geological feature is that contact likely to be?

The gray material is extraordinary. Looks like a slump of fine grained stuff, with small wind ripples over the surface. Perhaps once the main slump stopped, a couple of other smaller slumps created those cross-slope gulleys. The contact with the blocky area at the back has little pale broken shards along it.

That's the one, it's really intriguing. To me at any rate.

Ah, I hadn't thought of looking as far back as the Bay of Ducks. I was still focused on the wonders we're seeing at the St Mary/Beacon area. I'm looking forward to more Pancams of this area, this could be a key to understanding the formation of the Bays.

Sorry to have drifted OT, I hadn't thought of Duck Bay since that _seems_ like ancient history. But this is part of the series of the to-be-famous "CSM Panorama", so it's not entirely OT.

--Bill

Opportunity has moved. Pancams and navcams are in!!!!

Beacon as "Edge of Evaporite Slab on Near Rim".

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Q.E.D.

They're heading for the tip of the cape by the look of it. So the next drive will produce spectacular views of the crater. CSM is 30-35m above the crater floor I figure (roughly derived from shadows in HiRise image). Standing up there should open up all the rest of the crater to view. It'll be one of the few opportunities to point the pancam straight down, and see something other than deck. Cancel all leave.

Beautiful! Our first really good look at the beacon outcrop. Thanks for the pan, Shaka.

MarkL - I and someone else (James?) measured the height above the crater floor at Duck Bay and got about 70 metres (jpl has given a similar figure). CSM/beacon is probably a couple metres higher than Duck Bay rim.

But you're right - it's going to be a heck of a view!

If Beacon is the last fragment of an evaporite layer that has been eroded-away everywhere else around the rim, I will be thoroughly flummoxed. It is at the highest point of the crater rim! I would expect it to be the first to go, not the last!? Oh, Dearie Me. I must have a close-up examination of this Wonder Rock, that led us such a merry chase across the Hematite Sea for so many months.

And this is the (manual) stitch of L2 pictures, showing North rim... next station cape St Mary!

an interview with Steve Squyres by the BBC

http://news.bbc.co.uk/1/hi/sci/tech/6128594.stm

He does note that they will most likely go into Victoria whether they think they can get back out or not.

If it's really 70, that'd be impressive. I was measuring the height of the right triangle formed by joining the tip of the cape to its corresponding shadow on the crater floor to a point directly below the tip (ie. the height of the scarp). Since the floor is not flat but descends toward the centre of the crater, this would be a high estimate for the height of the cliff below CSM. I think it came to 37m. Maybe your calculation (sorry missed where you posted it) was Duck Bay height above the very bottom of the crater which I'd agree would be over 70 m. CSM was the highest point I could measure and casts the longest shadow.

Edit: FWIW, here's what I worked out ... (again these are cliff heights, not absolute heights above crater bottom)
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Yeah, I meant 70 metres above the lowest part of the crater floor (more or less, it's hard to say exactly where the lowest point is). Here's the post.

Your values do sound reasonable, to the tip of the shadows. But the heights to the base of the cliffs will be a fair bit lower, since the crater floor will drop quite a bit between the cliff base and the shadow tip. Frio is only about 15 metres from top to cliff base. Still a heck of a drop, of course!