Some pretty complex driving by the look of it:

http://qt.exploratorium.edu/mars/spirit/fo...E0P1214R0M1.JPG

Now this is odd:

http://qt.exploratorium.edu/mars/spirit/na...E0P0617R0M1.JPG

It looks like some of the rocks have slid down the dune

Fascinating image. I'm not one of the "water, water everywhere..." crowd, but that odd pattern in the dust immediately below the bluff outcrop looks positively _splat-like_.

What do you make of it?

--Bill

I thought it looked like a thin/harder crust on top of the dune had slid down slightly.

Another view: http://nasa.exploratorium.edu/mars/spirit/...E0P0123L0M1.JPG

That is my take of it too: A hard, plate-like crust slipped down the incline during the recent past. Of course, it begs the question, why is there crust at that spot?

I wonder if Spirit caused a shifting of the outcrop when it drove up on the other side of Larry's Lookout on Sol 409, and drilled a rat hole on Sol 416? That slip looks extremely fresh. I 'm not sure how close this slip is to where Spirit was before, though. If the rock behind the "soil" was somehow pushed outwards, it could maybe cause the soil to break like that even if there wasn't a discrete crust- I think I've seen similar patterns when playing with damp sand on a beach. Very cool!

Ignore this one- not sure what happened...

I have the impression Spirit's previous visit to Larry is rather far on the other side of the outcrop. Look at jvandriel's latest panorama in the Jibsheet thread to get an idea.
The "caking" is funny and cool

From Steve Squyres' latest update http://athena.cornell.edu/news/mubss/

"At Gusev, Spirit has arrived at a safe standoff position for observing the eastern side of Larry's Lookout. We're going to sit here and do some serious Pancamming for a sol or two, and then we're going to have to decide what comes next. There are a bunch of possibilities, and we're going to have a very interesting time choosing among them."

The first thing I thought was it slid down when Spirit did its turn just below it. But looking back I see it was already there on sol 483
http://marsrovers.jpl.nasa.gov/gallery/all...B2P2418R1M1.JPG

Also already on sol 442: http://marsrovers.jpl.nasa.gov/gallery/all...28P2394L5M1.JPG (probably the first shoot of it)

Or already here "somewhere" in a Navcam on sol 438: http://marsrovers.jpl.nasa.gov/gallery/all...00P1625R0M1.JPG

P.S. Hey forum, nice you are alive again

A closeup of the "overhang" as I call it, or the "dragon head" as I think someone else called it:
http://nasa.exploratorium.edu/mars/spirit/...E0P2421L7M1.JPG

A panoramic view of Larry's Lookout and surrounding seen from Jibsheet.

Pictures taken with the Nav cam on Sol 487.

jvandriel

And a view of the other side of Larry's lookout also taken with the Nav cam on sol 488.

jvandriel

I was wondering about weather spirit had been up there previously. But it realy doesn't look like it. I haven't seen anthing to indicate that it was. It doesn't look like it happens alot. I haven't seen anything that looks like old slides. It might be rare and we got lucky. Strange that it seems crusty. That would indicate that the grains were not active. The slope is static since it was cemented.

Anybody have any insights... ?

Regarding that weird little slope failure thingy on the south side of Larry's lookout/Watchtower: During the Viking 1 mission there were two events like that, not seen as clearly, but in hindsight very similar indeed to this. Both of them happened during the mission so there were before and after shots. Both on similar steep drift slopes and the best seen one clearly showing a slipped surface layer like this. I don't have my stuff with me as I write this, but it would be easy to track down, it was widely reported.

Phil

Tonight at her talk at JPL (of which I only caught the tail end on NASA TV...curse you inaccurate satellite listings!), Joy Crisp mentioned the slip feature and seemed to imply that the team thinks that ratting earlier caused the disturbance. She even used the word "Duh!" to describe the reaction after they first noticed it.

Yeah. I missed her lecture, too. Had to work late. It will be repeated on Friday, but it is not clear whether that will be broadcasted or webcasted again.

The sediment in this location is piled up quite steeply and is probablly very close to, if not greater than the expected angle of repose, which is about 35 degrees for normal sediments on earth. I'm not certain if that angle would be different on Mars, but this slope is clearly very steep. http://quest.arc.nasa.gov/mars/ask/soil/Di...Mars_soils_.txt
If it is an over-steepened slope, somewhat stabilized by weak cementation of the grains by precipitated salts or a slight amount of moisture, the slump was probably just waiting to happen.

We may have simply been lucky to have noticed it. But, as Edward has pointed out, we really haven't seen anything that looks like old slumps/slides. As simple as it is, this really is an interesting feature.

The fact that it is visible in images taken quite a few sols ago from a distance makes it difficult to imagine it could have been caused by Sprit's activity/ratting. (Tman spotted it as far back as the sol 438 navcams.) I can imagine it could have been caused by a gust of wind, a loud sound, or a slight seismic vibration.

On Sol 489 a series of pancams were taken of this area. Here is a portion of it that shows the upper part of the slope failure.

A panoramic view of the top of Larry's Lookout through the eye of the Pancam and L7 filter of Spirit.
Photo's taken on Sol 488.

jvandriel

As I suggested earlier, the slump could have been caused by the ratting on the other side of Larry's Lookout, which was done on sol 416, before there were any images of this slope.

I don't really think the RAT caused the slump feature. The ratting is a fairly gentle process (and was it only brushing anyway?... can't recall now, but they are limiting the RAT use as it wears out) - and it was quite a distance away from this spot, not right on top of it. And the Viking examples which I mentioned above suggest to me that it's not really so unusual. (see page 38, "The Martian Landscape" , NASA SP-425, for the first and best-seen Viking example).

Phil

Can anyone comment on how the surface materials in these drifts are bonded into plates?

Well, this new hazcam shot really turns my "slump was probably just waiting to happen" hypothesis upside down. If the dust on that slope was so sensitive to vibrations, I suspect Spirit wouldn't have gotten this close without disturbing it further.

http://qt.exploratorium.edu/mars/spirit/fo...EEP1214L0M1.JPG

Some color (sorry, I don't have time to stitch them together):

I admit it seems unlikely that ratting the other side of the outcrop would cause this slump (they did grind, not just brush, on Larry's Lookout -see Sol 419 Hazcam image). And I remember the Viking 1 slumps, at least one of which was far enough from the lander that the lander can't reasonably have caused it. I'm just struck by how this looks *so* fresh, and how I can't recall seeing any examples of more degraded slumps previously. It is striking that Spirit's wheels digging into the slope have not precipitated further slumping, though maybe the slope is more susceptible to failure by a push from behind than by digging from below.

Here's a pancam mosaic of four of the images posted by Mhoward. I'm waiting for the other frames with missing data to update, hopefully.
Very intriguing this feature.
Cheers
Nico
awalkonmars new Spirit sol 489

The Crusty unit does appear to be thicker and more coherent than the adjacent areas. After detailed MI, she should give this unit a poke and see what it does. It is clearly aeolian, and my guess is that it contains a hygroscopic salt that is cemented with the humour of atmosphaeric moysture...

--Bill

I agree regarding the slumped material. The platy layers look like a caliche style of cemented deposit, and perhaps the hygroscopic salt hypothesis is the right one. This sort of deposit has been seen right back to Viking 1, though the salt-rich soil is a new bit of the jigsaw!

Well, given that they've gotten right up close to the slump, I imagine that a little brushing with the RAT might be in order. That should be more than adequate to have a look at all the layers, as well as maybe trigger additional landslides.

How about season, alternatively sun dont reached this slope over wintertime?! And now in the actual season the slope get warmness and this has activated "anything" or caused layers in the sandy soil at least?!

Yes, I also agree that it's a hardened layer of duricrust that was disturbed in some way by the rover. Duritcrust was previously observed at Opportunity, Pathfinder and Viking landing sites.

http://marsrovers.jpl.nasa.gov/gallery/all...03P2584L7M1.JPG

This paper describes the process involved and you can also read a summary on my site under the "Duricrust" heading.

http://www.lpi.usra.edu/meetings/lpsc2004/pdf/2188.pdf

Cheers,
Aldo.

The paper on the duricrust posits some very credible processes, and when one considers the Viking 2 images of hoar frost at the landing site then a ready source of water is apparant.

I'm reminded of the 'mineralisation' process which occurs in sandstone used for buildings (a big chunk of Glasgow, where I live, is built of Old Red Sandstone from the north-west of Scotland) and which often preserves 400 MYO bedding planes etc in the facades of houses. I wonder whether the aeon-long formation of duricrust would eventually give us rocks comparable to terrestrial sandstone, or whether it would always remain rather more friable and delicate? The exhumation of buried features we see from orbital imagery suggests that there are episodes of harder/softer rock deposition, which may be linked to relative abundance of water (eg a nice big impact could create a briefly wet Mars with well mineralised rocks, with a gradual return to the fairy-cake stuff as time wears on).

Ah, the ghost of Tommy Gold beckons!

Nico, missing (right) portion in the next Sol:

Regards.

Shiver me timbers! Are you suggesting we'll eventually be drilling impact sites on Mars to harvest hydrocarbons?

Sorry this is long, but I found myself on a roll...

It definitely seems to be a "crusty unit," but going so far as to call it a "duricrust" seems unwarranted. I really haven't yet seen anything I'd call a true duricrust on Mars. I really prefer the "weakly cemented by salts" hypothesis. Water ice is a second choice for me.

There were a few images from around sol 110 taken near Endurance that keep popping up as examples of duricrust, but taken in the context of the surroundings, they appear to me to be soil/dust covered slabs of fractured bedrock that were disturbed by Oppy's wheels.

Purported examples of duricrust:
http://marsrovers.jpl.nasa.gov/gallery/all...03P2584L7M1.JPG
http://www.lyle.org/~markoff/pds/234567/1P...87L234567C1.JPG

Context images showing the dust/soil covered plates of broken-up bedrock surrounding Endurance crater:
http://marsrovers.jpl.nasa.gov/gallery/all...3P2366L7M1.HTML
http://marsrovers.jpl.nasa.gov/gallery/all...3P2366L7M1.HTML
http://www.lyle.org/~markoff/pds/257/1P137...P2361L257C1.JPG
These are some that have been partially exhumed:
http://www.lyle.org/~markoff/pds/257/1P138...P2295L257C1.JPG
http://www.lyle.org/~markoff/pds/257/1P138...P2295L257C1.JPG

The 'Tommy Gold' reference was more in regard to his ability to think out of the box - a bit like Fred Hoyle. A lot of their ideas didn't pan out, but they were always interesting!

And as for the cosmic origins for hydrocarbons hypothesis, well it seems unlikely at first glance but...

"Duricrust" is a term that was applied to some Viking soils back in the 1970s, to describe the cohesive properties of the upper few mm of some of the soils. As far as I've ever been able to tell, it's used in a descriptive, not a diagnostic, manner -- it describes the cohesive qualities of some top layers of Martian soils. It doesn't pre-suppose a reason for the cohesiveness, i.e., it doesn't assume that the duricrust is created by a permafrost layer or anything like that. (So the idea of an absolute "true duricrust" doesn't really enter the discussion, I don't think.)

In fact, the conclusion of the original Viking team was that the duricrust is likely a weakly cemented unit resulting from evaporation of salts from groundwater. Since no evidence of current groundwater was returned, they didn't state that assumption as certain, but I know it was the preferred theory for the observed phenomenon.

-the other Doug

Tommy Gold's problem wasn't that he thought outside of the box (which claim I question just a bit) -- it was that, in the face of overwhelming evidence that his theory was invalid, he not only stuck to it, he got louder and more shrill about it right up to the point where men actually walked on the Moon.

Face it -- after two successful Luna and five successful Surveyor landings proved that the lunar regolith was sturdy enough to support all sorts of weight, the man was still strongly (and publicly) pressuring NASA to include a set of large weights with brightly colored flags attached that were to be shot out in front of the LM as it descended, to make *absolutely sure* that the surrface below wasn't a meters-deep quagmire of lunar quicksand.

"Thinking outside the box" is no excuse for vociferously hanging on to theories that have been discredited.

-the other Doug

But a flag-draped LM would have been *entertaining* at the very least!

I know that the term had been used for similarly caked soils observed by a Viking misssion, and even by many other scientists studying other parts of Mars over the years. All I am saying is, it that it's a misuse of the term. Duricrust is a useful geologic term which has a much longer history than that of the space program. While the definition is fairly broad and open to some interpretation, it has always implied an indurated, strongly to moderately cemented soil or regolithic material. Ie, it is literally as hard as a rock, and therefore has the ability to control the later geomorphic evolution of the landscape. Laterites, bauxites,ferricretes, silcretes, even caliches are classic duricrusts.

Apparently most of us agree that whatever we call it, this looks like some kind of a salt-caked crust. I don't want to debate semantics. It's just that I hate definition-creep, especially when it erodes the value of a time-worn and useful term.

Tommy Gold and Fred Hoyle were similar "theory testing impaired"

They were wrong a lot of the time. They had tremendous abilities to sort through and select and interpret evidence in support of their theories and ignore evidence that blew their theories out of the water entirely. Much of the science they did in their later years bordered on or went over the border into crackpottery.

But when they were right, they were spectacularly right. Their theories were always worth listening to, and thinking about, even when you were 99.9% sure they were totally off--the--wall wrong

When I saw this front hazcam today I initially thought we would see MIs of the crust, but it's clear they are looking at the rock above.

http://qt.exploratorium.edu/mars/spirit/fo...EEP1131L0M1.JPG

Here is a mosaic of the MIs from today.


The clasts in this rock seem to me to be more angular than some of the other outcrops we've been seeing as we came up the hill. Looking at the pancams from Larry's outcrop I am wondering if I am seeing some evidence of graded bedding. Does anyone else see that?

Finally, back to the crust. It appears to me that this image captured evidence of some other, partially eroded, crusty dust in the upper right.
http://qt.exploratorium.edu/mars/spirit/pa...EEP2535L7M1.JPG

Seeing some of the microscopic images from Spirit last night reminded me a little bit of the images Oppy took at El Capitan and other outcrops in Eagle Crater. Is this going to turn into press conference material??

I had the same question. And there seem to be lower levels of outcrop available to look at if they're feeling lucky... I can't wait to see what those look like.

I had exactly the same thought when I saw these latest MI pics. One in particular stood out:

http://qt.exploratorium.edu/mars/spirit/mi...EEP2957M2M1.JPG

Look towards the right of the image, say about 80% of the way towards the right edge, and just over half way down. It looks like a "blueberry" encased in rock.

I'm with you, gentlemen, this stuff DOES look like Meridiani, both up close and from a distance. I started a thread on this topic some weeks ago ("Spirit Hits Blueberries" -- you can find it via the "Search Forum" feature), and there was an initial flurry of interest -- but NASA/JPL/Cornell has not been very definitive about what they are finding. But maybe the stage is being set anew.

On the other hand, I have to keep reminding myself that the exposed surfaces we are seeing are the result of perhaps hundreds of millions of years of weathering via wind driven sand, dust devils, etc., so perhaps this TENDS to create a characteristic-looking surface regardless of the actual composition of the rock. I mean, imagine taking your beloved rock collection, sandblasting it for a couple of hours, and then trying to figure out what's what.

But darn, this Larry's Lookout stuff does have the same "ropey" appearance as the stuff Oppy has been seeing thougout!

Glenn

OK. I can appreciate that there are certain similarities among MI images taken of rocks by both rovers. But both rovers are commanded by people looking for layered rocks, and all of those rocks are presented to us microscopically as grayscale images.

The devil is in the details of the rock texture; the grain size/shape/orientation distributions. I think the rock compositions from spectral data is quite different also, but I don't have links to that at my fingertips. The MIs of the rocks from Eagle crater look very different to me from the latest MIs of Larry's outcrop.

There are so many images from Opportunity that one might compare these rocks to, but I chose a few from some press conferences and put them into a crude montage with the recent mosaic from Spirit.

The full six frame mosaic sol 489:

http://paranoid.dechengst.nl/mars/Larry%20Lookout.jpg

Color needs correction though and Photoshop drives me crazy with all the options Anyone willing to write a nice tutorial ?

I have a better link in my bookmarks at home but this guy seems to have written a decent overview and there is a motherlode of tutorial links here. You can also get stuff on the adobe site, but it requires registration. I'll post more in the imagery forum later, if I remember
I have an "on again - off again-love-hate" relationship with photoshop....

My first impression here was that I was looking at mud. The surface appears smoother, more reflective, perhaps finer grains collecting in a sheltered location?