Cape Verde

sol 1487 ( Mar 31, 2008 ) L257 6x2 of Cape Verde:

The adventure continues...

I thought the Duck Bay Adventure topic was getting kind'a long, so I have started a new topic on the exploration of the Verde cliffs of Victoria.

It is an opportunity for Steve & Ray's excellent adventure.

Hort

Beautiful stitched panorama as usual.

aicall; Thanks, I am also bewildered. I don't know what is going on. But the picture is indeed consistent.

I don't think that at anytime we were seeing desert pavement effects. I think that here the berries are relatively soft and are eroded over relatively short time frames and are replaced by berries eroding from the above cliff face.

On the plains it is a different matter. I think they are produced surficially, probably as salt berries which become covered with hematite with time.

Winston

Hi Hort... Nice image!

I have not seen the movie Steve & Ray's excellent adventure. The write up through the link you provided does remind me of a great British series called Dr. Who http://en.wikipedia.org/wiki/Doctor_Who

It's interesting to note that phone booths are used both by Stephen and Ray & Dr. Who to travel through time. Although Dr. Who is not an earthling, but rather a time lord.

In LWS Replies # 650 and 651 of the Duck Bay Adventure the image shows berries on the surface and a certain depth of finer grained material with fewer berries below and bedrock beneath the finer grained material.

Perhaps the berries only form during the right conditions.

If we see berries interbedded within a rock layer, then maybe that berry "fossilized" there. But there are instances where the berries seem to grow within the rock also.

Maybe someday these surficial berries in Repy 650 would be buried and fossilized. Certainly there must be stratigraphic layers of berries along the outer circumference (wall) of the bottoms of these craters beneath the dunes. These layers could simply be the result of berries eroding out the surrounding matrix and rolling down hill to be embedded within the surface of the current dune layer. Over time more windblown sediment fills the crater and new dunes cover the most recently placed berries. Over long periods of time, other berries roll downhill and deposit on top of the windblown material on top of the last layer of berries.

I believe that we have seen examples of several sequential layers of fossilized berries in other areas. So why are there no apparent berries beneath the surficial berries in reply 650/651?

Maybe the finer grained material was displaced by the heavier berries when the rover wheels stirred things up. If I had a pile of dry sand with a few layers of spherical copper BBs inside it and a bunch of bbs sprinkled on the surface and I drove into it and backed away with the rover what would we see? Many of the BBs would sink in the sand due to the agitation and the “fluffing up” of the lighter material. The heavier BBs would sink into the finer material and you would not see them as frequently as you might expect on the exposed surface of the (dry) sand. Also the different colored subsurface berries (brown) are more difficult to see in the brown finer subsurface matrix.

The scale is important. How deep is the exposed hole in reply 650-651? A couple of inches? The image appears to show a surficial layer of berries with bedrock below and finer material in the middle. Maybe a berry forming event occurs at the surface in conjunction with atmospheric and subsurface moisture/gasses while the bedrock turns to dust.

Did the berries form closer to the bedrock surface and the bedrock below turned to dust below them during and after their formation?

Do the berries prefer to form at the surface from the surrounding dirt further above the bedrock?

Is there a lag between berry formation and bedrock disintigration or do they happen at roughly the same time?

What influence do the shifting sands, subsurface outgassing, varying atmospheric moisture concentrations, and global dust storms have?

Many questions.

Maybe the berries were originally more evenly distributed throughout the finer grained material. The wind may have blown away the finer grained material in some areas to reveal localized concentrations of berries as LWS Reply 1 of this thread brought up (desert pavement: http://en.wikipedia.org/wiki/Desert_pavement ).

I would guess the answer is a combination of some of the above factors. I believe that atmospheric moisture/subsurface outgassing, and daily/seasonal temperature variations are key in berry formation.

Hi rpage

Good to see that someone is coming around to my way of thinking about the berries!!

The proneness to erosion of the berries is probably the key. Search the surface images of berries on the plains and you will see lots of broken berries, small berries and dark coloured dust. Methinks they are not solid hematite.

Winston

LWS, Why do you keep stating that they are solid hematite? The 2005 McLennan paper found quote the spherules are composed of a mixture of about 50–60% hematite (confirmed by Mossbauer and Mini-TES) and 40–50% terrigenous basaltic material

The scuff shows a classic, mature desert pavement. To quote from Wikepedia 'Ultimately, a fine-grained desert soil is found immediately below a one or two-clast layer of clasts (the pavement'

RJS. Dr Who - an absolute classic born 1963 and still going. The ultimate low budget success story with special effects consisting of caves made of plastic garbage bags and cardboard robots. Wasn't the same after they paid off K9 though.

Brian/RJS,
I remember some of the old Dr. Who shows.
I love the way they would glue some sparkely sprinkles on a black garbage bag, put a guy in it, and there's your monster!

Uh-oh.

3D animation of left front wheel for sol 1491,1493,1495:

Looks like Oppy is "digging in".

Here is the rear view.

Perhaps a 'sorting process' has been/is active here. Could the layer of surficial berries represent a wind-exposed fossilized lakebed? Wind and weathering seem too intermittant to produce these berry and other 'pavements'.

thats very easy to imagine James.

Are they puposely digging in next to the plate to see the strange goin ons in these dynamic areas? One question i would have is, Where do the berries go next to the slabs? Mostly there is just dust, unlike open areas, where somehow the berries float on dust.

Hi Hort

Some help here please. Below is an anim of the wheel scuff between sol 1444 and 1491 (If my calculations are correct). I am not certain if it is the same scuff imaged on 2 dfferent days with no interim disturbance by the rover or if there was some disturbance by the rover. If it is the same scuff and there was no disturbance by the rover the changes are quite remarkable. Grateful if you could properly align and redo the anim.

Once again, note the smooth area on the top of the scuff in the sol 1444 image, looks to me like a liquid flowed there and the area turned to ice. On the left bottom of that image is a similar area that looks like ice. In the sol 1491 image the soil has settled somewhat; there is a crack exposing the typical bluish fine grained area just under the berry layer; many of the pre-existing very small berries of the sol 1444 image are now gone, replaced by fewer larger ones; the smooth upper area that I said looked like ice in the sol 1444 image has now settled down to show the rough soil deposited there by the flow and the rover wheel; the same for the former lower area; the areas that looked like ice are now gone; much of the trench has settled; dust has been removed from some of the large berries; wheel tracks that look as if they were covered earlier have now appeared on sol 1491; etc. etc.

Meridiani is still very weird.

Winston

Oops!!

Wrong image!

This should be it:-

Winston

The two scuffs ( 1444, 1491) were in two entirely different areas:

Near Gilbert layer:

and

On the way to Cape Verde:

Reply 10 and others. The distinct and reasonably deep tracks where a few 'berries' have rolled down to the bottom testify to how fine and dry the dust is.

I'm not sure what the driver and manager's intentions are. The current position seems to be right over the sol 1491 deep scuff so we know the surface this low in Victoria is friable. Why do they seem to be aiming deeper into the crater when there seem to be a number of paths leading to the cliffs that would keep the rover on bedrock? Are the short and digging in wheel rotations the result of planned drives terminated automatically due to slippage or are they doing something else?

Hi Hort

Thanks!!
I was too tired to check the nav cam images last night.

The differences and similarities between the two images are still interesting however!

Winston

Sol 1495 location of wheels:

brian, I think Oppy is a few meters beyond the scuff -- in fact about 5 meters. I drew the axis of the wheels as best as I could determine from the front and rear hazcams. The contact points of the wheels should be at the ends of the three lines. It looks like 4 are in dust and two are on rock.

I too am puzzled about where Oppy seems to be going. The center line of the rover seems to be pointing towards the barge boulder at the base of the scree -- not at the cliffs of Cape Verde.

Maybe the plan was to turn left towards the cliffs on the small outcrop ahead??? Guess we will never know.

Hort, mayhap my gyro has toppled, but isn't the middle wheel position you designate exactly where the wheel scuff imaged in reply 12 was made? The bedrock is a perfect match.

The reply 15 image was taken from (I think) the sol 1486 position before they went down, scuffed and then backed up to review the result. They then apparently went back down and sat over that position with their two forward sets of wheels positioned on what they knew from the scuff was fine dust. A brave decision on such a slope.

Your reply 7 animation looks more and more like planned drives terminated due to excess slippage. In fact while the sol 1491 seems to show slippage going forward, the throw of dust from the three subsequent sols show that they were trying to reverse.

One can only hope that they are doing something clever and all is well.

Er, yes, brian the middle wheels are within a few cm of the scuffs -- maybe a few cm to the right of the scuffs.

I didn't compare the post scuff Navcam images to the reply 15 image until last night.

Ooops.

I think I mistakenly thought this 1489 rear hazcam image was taken from the scuff position

and compared it with this 1491 position

and concluded Oppy was already 5 m past the scuffs. I remember looking for the scuffs in this image and wondering why I couldn't see them!

I have to admit complete surprise that Oppy was able to back upslope from the scuffs with apparent ease -- but can't proceed downslope past them.

Perhaps there is another wheel problem? Remember, the right front wheel has been unsteerable since April, 2005!

1FL0 1493-1496:

Looks like there was some success trying to turn and back out of the hole.

Maybe the plan to attempt Cape Verde will be reconsidered -- if Oppy can retreat to solid ground?

sol 1499 ( Apr 12, 2008 ) - still stuck:

but a few cm progress(?)

However,

the rear right wheel is off the ground and the rear left wheel may be digging in.

the center wheels are most likely spinning in the the scuff marks.

doubleplusungood.

sol 1497 R127 view of left front wheel:

Here is L257 2x2 of right front wheel and L257 2x2 ahead.