Do a difference and you'll see that they differ in the noise in the lower right corner. That's a typical sort of change for an image resent - the original version had some parts corrupted by noise on downlink and the next attempt gets it right. Sometimes the parts are so corrupted that they're rendered black, which makes it obvious.

But... if it was resent, that implies that the flash system is back up and running, correct? Otherwise, how would it be there to be resent?

-the other Doug

Exactly!

http://mars.nasa.gov/mer/mission/status_op...ll.html#sol3937

New Flight Software was uploaded on 3942, booted successfully on 3943 and a reformat was then planned. As those above have noticed it looks like that reformat has happened and the flash is now in use.

The complete Navcam L0 view taken on Sol 3946 and Sol 3947

Jan van Driel

Click to view attachment

The colour mosaic from sol 3946 to plan where to park for IDD work.



Tosols drive took us to here:

Click to view attachment

Two very different types of rock and the respond to wind erosion very differently.

Along the top right border of the first image, and also seen in the second in the corresponding place above and to the right of the presumed target, appears what looks very much like a large loose shatter cone, with the cone pointing more-or-less towards the camera. Beautiful, unambiguous evidence of impact metamorphism, if so. What do you think?
Don Burt

Entirely plausible, but I have to ask one thing: is this the first one of these you've pointed to? Given the enormous number of individual chunks of rock imaged by the rovers I wonder about the odds on one looking like this just by chance.

I saw what I thought looked like shattercones a while back, sol 3894, and mentioned it on Twitter. A couple of geologists (David Rothery, Gordon Osinski, Fred Calef) replied and agreed they had the appearance of shattercones, but couldn't dismiss wind ablation, so I'd say the jury's out, but I'll bet people are studying these features. Then Justin Cowart chimed in with this other example.

When geologists argue about an ambiguous "either/or" situation, commonly the correct answer turns out to be "both" and wind abrasion is certainly needed to selectively erode things so that their underlying strengths and weaknesses (and in the present case, perhaps intrinsic conical shape) can be seen. If its conical shape was caused solely by wind, you might expect similar loose rocks nearby to have the same shape, and they don't, plus it appears to be conically foliated internally.

Deep Mars should be nearly saturated with shatter cones in places, given the intensity of impact cratering at the surface, but wind erosion alone has apparently not been very effective in exposing them, even over billions of years, possibly because most are still too deep beneath their related craters, or have become buried under younger rocks. This loose shatter cone, if that's what it is, could have been excavated by a later impact, and then dumped on the surface. Emily's examples, of multiple adjacent cones in bedrock, are slightly more ambiguous w.r.t. shaping solely by wind, but they do look exactly how shatter cones should look in place, including foliation.
Don Burt

Very informative Emily and Don, thanks.

Two RGB PanCan images from Sol3848


Click to view attachment

Click to view attachment

And two anaglyphs


Click to view attachment

Click to view attachment

That is my take, too. You have a situation where multiple processes have occurred repeatedly over aeons and it can be a rather complex hodgepodge to sort out. In many ways the strong weathering, erosion and deposition cycles we have on Earth can neatly punctuate many processes.

--Bill

Re: shatter cones vs. wind erosion.... Is it possible to rule out wind erosion depending on how the structures are oriented?

Seems like the flash masking hasn't yet occured - according to the latest update:

I'm not sure I even understand your question. How logically can you "rule out" wind erosion if you see shatter cones, inasmuch as wind erosion is needed in order for you to see them?

If you meant, does their orientation relative to the prevailing wind directions unambiguously indicate that they could have been formed by wind alone, then sorry, I won't try to touch that one, other than to note that it's their internal foliation (pattern of fractures) as much as their crudely conical external shape that reveals that they are shatter cones.

If you meant, does their orientation relative to a crater reveal their intrinsic genetic relationship to that crater, and therefore that they must be "its" shatter cones, well, that might theoretically be true, if we could see all rocks as in an idealized cross-sectional diagram from a textbook. In reality we are looking only at a poorly-exposed present-day erosion surface, so my short answer to that interpretation of your question would be "ambiguous at best, for a variety of reasons*." Disclaimer: I don't claim to be an expert on shatter cones; like Emily I know what they are supposed to look like and a bit about how they form. That's all. Therefore, I apologize if I have misinterpreted your question.
Don Burt

(*Possible reasons for ambiguity: overlying parent crater eroded, multiple candidate craters in the vicinity, bedrock shattered multiple times, and refraction or bending of blast waves, and I've probably overlooked some.)

Sol 3951 pancam view of Speckled Hill:
Click to view attachment

I seem to have a knack for flubbing my entire point by a single misplaced/nonplaced word....

I meant ruling out streamlining from wind erosion being responsible for the pattern/texture/structures.

Some possible clues of actual shatter cones?:

- Shatter cones would be expected on all sides of rocks, not just one.

- Occur in sheltered spots that wouldn't be subjected to winds.

- Visible on (relatively) freshly fractured surfaces.

- At an angle inconsistent with that expected with wind sculpting.

- Wind sculpture superimposed incongruously across a preexisting shatter cone texture.

A thorny issue with interpreting features on Mars is that one has to always be mindful that we often take the effects of terrestrial processes for granted that would not occur on Mars at all. I'm speaking for myself here. Recall all the space art inspired from earthly scenes depicting 'clean' rocky outcrops that 'assume' rain and stream erosion....

An example in this case: Shatter cones on all sides? That would be expected on Earth, but on Mars, that same rock, instead of being weathered by various processes, may only be subjected to a unidirectional wind.

Because of the long-term, dramatic changes in obliquity on Mars due to Milankovitch cycle effects (http://www.ifa.hawaii.edu/~norb1/Papers/2008-milank.pdf), I wonder whether wind patterns would cycle through prevailing directions, thus slowing down or randomizing any preferential erosion patterns, or at least making wind-based interpretations somewhat trickier to validate.

My understanding of shatter cones is that you can see a single shatter cone in a given rock face quite readily. At least, shatter cones on lunar rocks often manifest as single conical fracture zones in a larger rock face. House Rock, at North Ray Crater at the Apollo 16 Descartes landing site, displayed a single shatter cone along a 10 by 40 meter rock face, and it was unquestionably a shatter cone. So, no, just because there was once enough force pushed through a rock to cause a shatter cone doesn't mean you'd expect to see shatter cones all over the rock face, or on all sides of a given, smallish rock.

Also, with its obvious history of impact churning, the Martian surface should be expected to display evidence of the powerful forces released by hypersonic impacts. It would be unusual, and begging an explanation, if we didn't see shatter cones in some of these rocks. The question should not be "Why are we seeing a shatter cone in the occasional rock?" It should be "Why haven't we seen more shatter cones in these rocks?" The answer to this question is likely that wind erosion has subsequently altered the faces of most rocks to such a degree that telltale signs of shatter cones have been obliterated on many rocks where they might otherwise have been observed.

-the other Doug

The pyramidal forms of many of the ventifact rocks we see on Mars speak to changes in wind patterns over the millennia. If prevailing winds have always been from a single direction, you would only see wind erosion strongly affecting the sides of the rocks facing into the prevailing winds. The pyramidal shapes strongly suggest exposure to long-term prevailing wind patterns from a variety of different directions. And yes, that means that, given a long enough exposure to winds in a given area, you would tend to see erosion on all sides of a given rock. Hence the pyramidal shapes.

-the other Doug

Speckled Hill taken on sol 3951.

Assuming that the current site consists of ballistic ejecta deposits (or possibly given A.J.S. Rayl's latest article, uplifted rim) it would represent the pre impact, near surface lithologies. Given that this would have reflected close to a kilometre depth of ejecta from Miyamoto and initial teasers on Jean Baptiste Charbonneau, what possibility is there that Opportunity could encounter examples of impact metamorphism?

It must be so frustrating to not have use of the Mossbauer any more. I hope they manage to unravel the mystery of these unusual rim rocks with their remaining suite of instruments.

All this talk of shatter cones has caused me to do some web searching. If you'll indulge my new-found 'knowledge':

Contrary to my novice idea that impact cones would be found in the bedrock deep beneath a crater only to be excavated by a subsequent impact, it seems that shatter cones created by the impact forming the crater can be found in that crater's rim/ejecta as well as a central peak, if one exists. At least as I read it. (See my highlight in the quote below.)
http://www.psi.edu/epo/faq/impact_cratering.html

Below, from shatter cones of the haughton impact structure, canada (PDF), is a diagram that seems to illustrate this finding of shatter cones in the crater rim as well as a central mound. The red dots indicate "Shatter cone localities within the central uplift" and the yellow dots are "Shatter cone localities within megablocks of the ballistic ejecta blanket." Also noted is, "Shatter cones are found throughout the crater-fill impact melt breccias so these localities are not shown."

The crater is about 15km in diameter, but see the un-cropped version at the link.


Click to view attachment

A fun image from the same paper to illustrate that the formation of shatter cones is far from understood:

"Two complete cones pointing in opposite directions. The specimen is ~13 cm across."


Click to view attachment

The Navcam L0 view on Sol 3949.

Jan van Driel

Click to view attachment

and the complete Navcam L0 panoramic view taken on Sol 3948 and Sol 3949.

Jan van Driel

Click to view attachment

Such a scenic place with a great name. Marathon Valley! The latest Rayl update (also mentioned by fredk a few posts up) was definitely worth reading for those catching up a little bit like me.

Here's a circular version of Jan's panorama. It looks like the hill on the south side of Marathon Valley is being called Swann Hill - or at least the imaging sequence is being called that.

Phil

Click to view attachment

The Pancam L2 panoramic view on Sol 3950-Sol 3954.

Jan van Driel

Click to view attachment

And in colour:

Spectacular, James. I almost wish it had been called "Fanged Peak"...

The view ahead Sol3955



Click to view attachment

And a NavCam view



Click to view attachment

As above but with a Hard Light mix to hopefully emphasise relief features.



Click to view attachment

Also, the colour and structure of the highlighted rock seems to be quite alien to it's surroundings. (At least to my untrained eye).


Click to view attachment

Agreed. It is clearly not part of the bedrock and has been transported from elsewhere. The apparent shatter cone discussed above (beginning on Mar 4) and other rocks at the top of the ridge appear to be made out of the same material.
Don Burt

There is nothing alien about that highlighted rock. It is one of a family of "scoriaceous Burple rocks" present on the ridge overlying the possible "shattercones" in the area of "Site Sgt Chas Floyd", aka Site 194/0000.

--Bill

dburt, thanks for that reply. I struggle to link previous posts to that with which I am immediately concerned. (Must do better)

BillHarris, regardless of what it is made of, as far as I am concerned, it is definitely alien to it's immediate surroundings.

I'm not sure I disagree with either of you, except that Bill seems to think that the bedrock is what appears to be shatter-coned (and it does, more or less), whereas I was talking about the loose possible shatter cone at the top of the ridge, made out of a piece of the "alien rock". These rocks look unusually porous, but I'm not sure yet whether they are truly "scoriaceous" (a bubbly igneous or impact melt texture) or merely brecciated (broken up by impact). Time will tell, I hope.
Don Burt

Foreground on sol 3956

I think Bill's comment dismissing "alien" is based on the fact that the only definition of alien as an adjective, that would seem vaguely applicable is "unfamiliar and disturbing or distasteful" (Oxford Dictionary) rather than any objection to algorithm's underlying contention. Dburt's describing it as transported is more accurate - an erratic without the glacial influence.

I stand to be corrected but the implication from Centsworth's quote that shattercones in the rim/ejecta blanket are associated with megablocks agrees with everything I have read. So if this much discussed artefact is indeed a loose shattercone then it is most unlikely to have formed in the Endeavour impact. Actually the concept that it could have initially been formed and deposited in a megablock in the Miyamoto ejecta blanket, which was then brecciated in the Endeavour impact with the shattercone ballistically emplaced within the rim is kind of exciting.

Sol 3958 pancam:
Click to view attachment

Sol 3958 in colour:

I was puzzled by this; checking the OED, the first definition of alien as an adjective is: "Belonging to another person, place, or family; not of one's own; from elsewhere, foreign." I think belonging to another place, from elsewhere, or foreign pretty much sums up the intended meaning in this discussion.

ADMIN: And with that, we can leave the discussion there. Back on topic please.

A panorama from the last l2 l5 l7 sols

How nice ! Thanks a lot eliBonora for sharing this work with us

Today is Reformat Day!

After living without flash, I can't imagine what getting it back will feel like.

Hope everything goes smoothly.

The Navcam L0 view on Sol 3962.

Jan van Driel

Click to view attachment