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Bye Bye Blueberries
Burmese
post Oct 24 2005, 03:25 PM
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According to Steve Squyres' latest journal entry, Opportunity is now seeing virtually -no- blueberries in the surface matrix anymore.

"...On top of that, Opportunity has stumbled onto something really new and different lately... the blueberries seem to be gone!..."

And a theory:

"But one possible guess at this point is that we have moved "up section" in geologic terms -- to rocks that are higher up in this stack of layered sediments -- and that the rocks at this level never experienced the concretion-forming process. It's an interesting hypothesis with interesting implications, and it's also one that could explain a few other odd things we've been thinking about ever since Eagle crater"

Looks like Oppy will stop for some intense IDD work in the next day or so.
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Tesheiner
post Oct 24 2005, 03:37 PM
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QUOTE (Burmese @ Oct 24 2005, 05:25 PM)
Looks like Oppy will stop for some intense IDD work in the next day or so.
*


Too early I think.
Steve said: "We're not jumping to any conclusions, but everybody is itching to get the IDD onto this stuff as soon as we get the chance."

Imho, that chance will be once Oppy touches hard rock again, not earlier.
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Tman
post Oct 24 2005, 04:01 PM
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Wow, it seems Erebus as the (maybe) highest place around Oppys landing site could be more interesting as ( I ) expected.


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paxdan
post Oct 24 2005, 05:07 PM
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I wonder if there is a correlation between the lack of berries and the size of the ripples. Perhaps the reason the terrain aroud Eagle and endurance was, for the most part, ripple free was the because the berries prevent ripple formation. As the berries decrease in number/size and dissapear the fines can become sculpted into bigger and bigger ripples.
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Guest_Richard Trigaux_*
post Oct 24 2005, 06:37 PM
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QUOTE (paxdan @ Oct 24 2005, 05:07 PM)
I wonder if there is a correlation between the lack of berries and the size of the ripples. Perhaps the reason the terrain aroud Eagle and endurance was, for the most part, ripple free was the because the berries prevent ripple formation. As the berries decrease in number/size and  dissapear the fines can become sculpted into bigger and bigger ripples.
*



And the terrain becomes more dangerous, alas, with big ripples.


The change is not only ripples, it is the overall etched terrain.
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Bill Harris
post Oct 24 2005, 06:55 PM
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Hmm, one gets so accustomed to seeing blueberries _in_ the evaporite matrix that one doesn't notice when they are _not_. I did a quick reality check and looked at the past several Sols of Pancam images of bedrock, and I see blueberries in the sand, I see blueberries lying on the bedrock, I see rough erosional surfaces on the bedrock, but I can't say that I see blueberries within the bedrock. At least, so it looks with these Pancam views and not an MI closeup.

Another piece of the puzzle: look at Doug Ellision's color image along the Four Lane at http://www.unmannedspaceflight.com/doug_images/erebus_3.jpg . I was planning to mention the color change in the dunes: instead of being blueberry blue, they now have a tinge of evaporite rust. Which may or may not mean anything, but we'll see if this puzzle piece fits...

--Bill


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CosmicRocker
post Oct 25 2005, 05:59 AM
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Wow, that took me by surprise, too. I looked back through my image archive to try to pin down the change. We have good observations of tiny berries in the rocks up until Sol 609. There could possibly be some in the rocks observed right up until sol 617, but the imagery is not optimum for such observations. I can't say a lot, but it cetainly seems that the change from small berries to no berries occurred quickly, and recently.

As one not afraid to go out on a limb with an hypothesis, here is my best guess as to where this transition may be. On sol 617 Opportunity captured this navcam image of a contact while climbing up-section.

The full size image is here.
http://marsrovers.jpl.nasa.gov/gallery/all...TOP1600L0M1.JPG

The layering in the lower part of the image is clearly different from that in the upper part. This looks like a significant contact to me. I can't imagine they will not go back to investigate this transition. I should say, they'd be crazy not to, unless there is a more convenient location to investigate.


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Bill Harris
post Oct 25 2005, 09:11 AM
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You-gottit, CR. I'd guess that this contact was reached Sol 215-ish, and Oppy traveled more or less along the line of this contact for the next few Sols. I think the contact was where the beds started to be finely laminated. Attached is a color image from Sol 618 showing laminated beds with an apparent unconformity/crossbed.

Moving topographically higher, this may may tie the paleo-meridiani playa to the shallow groundwater berry-concretion process. The lower (strat- and topo-) parts were more often saturated than the higher ground "back then".

--Bill


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CosmicRocker
post Oct 25 2005, 07:37 PM
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No doubt about it, the sol 617/618 outcrops were extremely interesting. I may have gone overboard a bit, suggesting they need to go back there for more investigation. I'm pretty sure that won't happen, but I really would have liked to see more close-up imaging around there.

I don't know if that contact is where the concretions disappear, but it has to be nearby. This area seems to have a lot going on, stratigraphically and structurally. Some places are really jumbled, and may indeed be impact ejecta. I agree though, that a change like the disappearance of the berries potentially has important implications regarding the paleoenvironment and/or the subsurface alteration processes. It sure could be an indication of a paleo-water table.


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ElkGroveDan
post Oct 25 2005, 07:43 PM
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QUOTE (CosmicRocker @ Oct 25 2005, 05:59 AM)
As one not afraid to go out on a limb with an hypothesis, here is my best guess as to where this transition may be.  On sol 617 Opportunity captured this navcam image of a contact while climbing up-section.  .
*


Good eye CR. I am in total agreement with you.


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ElkGroveDan
post Oct 25 2005, 07:49 PM
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QUOTE (CosmicRocker @ Oct 25 2005, 07:37 PM)
No doubt about it, the sol 617/618 outcrops were extremely interesting.  I may have gone overboard a bit, suggesting they need to go back there for more investigation. 
*


Perhaps, but it's possible we will encounter this same contact zone on the other side of Erebus as we head out of town.


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Burmese
post Oct 25 2005, 08:17 PM
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One would think that the science team would -really- want to use the IDD on an area where they can see this up-section change. Indeed, while poking into Erubus itself might show some layers that correlate with those at Endurance, discovering a layer above all that would seem to me to be a higher priority. They know they are on fairly high ground in the area and I would think they would be fearfull of passing it and descending (as they head towards Victoria) before they have a chance to fully analyze the new strata.

One also wonders if they didn't connect all the dots before they had passed beyond the transition zone. I can just imagine the daily meetings now as the tug-of-war over driving versus IDD work on this new strata are hashed out.
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Bill Harris
post Oct 26 2005, 01:11 AM
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This area of the north rim of Erebus is darn interesting. Anytime you start seeing changes in the lithology or stratigraphy over a short distance means it's time to look closer. Thus far, we seen the weathering rind, larger and more numerous "cobbles" (the dark angular pieces that I rant about), a decrease in Blueberry size in the ripple sand, Blueberries that are in the 10-12mm size range, the change in the Blueberry distribution in the evaporite matrix, a change in the bedding of the evaporite, those circular fractures in the evaporite plates and a host of other things. I realize that Oppy needs to get to Mogollon quickly, but there are lot of changes that should be looked at as we move on.

One thought, and not rtying to toot this horn: could the contact that CR noted be a "brine splat" feature? Just a thought...

--Bill


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CosmicRocker
post Oct 26 2005, 04:21 AM
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QUOTE (ElkGroveDan @ Oct 25 2005, 01:49 PM)
Perhaps, but it's possible we will encounter this same contact zone on the other side of Erebus as we head out of town.
*

You know, I started thinking about that on the way home from work tonight. The Erebus impact is likely to have uplifted the local stratigraphy, so Opportunity might encounter a stretch of down-section travelling as it leaves Erebus, before getting back to the regional up-section trend. There is a risk though. If the drifts are obscuring the section on the way out of Dodge, we may never see it. Then again, we should be treated to an excellent vertical section at the Mogollon Rim site.

I'm sure they were tempted to slow down and "smell the roses" on sols 617-618, but as has been previously pointed out by SS and others on the team, a complex mission like this requires making many compromises. I won't presume to second guess them. They are very likely at least several steps ahead of us when it comes to interpreting this stuff. This step-up is just the most recent of many up-section climbs made on the southward trek, especially since approaching Erebus. This last one just seemed significant because it appeared to corellate with the loss of the berries and it displayed textural changes as well. I'd have to suspect we are significantly up-section from Eagle/Endurance.


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Guest_BruceMoomaw_*
post Oct 26 2005, 06:08 AM
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As far as I'm concerned, the single most intriguing mystery left to us by the rovers right now is: what created the Blueberries? According to an upcoming poster at the Fall 2005 AGU meeting ( http://www.agu.org/cgi-bin/SFgate/SFgate?&...P21A-0140" ):

"There are two main possible reaction sets for formation of the Blueberries that are consistent with all current data:

"(1) Local concentrations of organic matter (pre-biotic or biotic) formed reduction spots in which a small amount of Fe3+ either in solution or from evaporite mineral salts, was reduced to Fe2+ and then diffused radially to form an iron oxide nodule by reaction with inwardly diffusing dissolved oxygen.

"(2) Similar local concentrations of organic matter could also have engendered sulfate reduction and consequent outward diffusion of dissolved sulfide reacted with iron in solution to produce an iron sulfide nodule, subsequently oxidized in situ to hematite (maybe via goethite)."

Organic matter. Well, well. It sounds too good to be true, but so far I haven't run across any alternative explanation proposed for the damn things anywhere on the Web -- and not for lack of looking.
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