Yes : great idea Emily and and at a place where the global view of Endeavour is terrific and where a 360° pan can be taken (i.e. somewhere near the top of Cape York), and -even better if possible- with low sun and nice long shadows to enhance the features

That is what I initially thought but decided that the surface looked "too glassy" to be deeply weathered. I imagine that the actual criteria for hardness of the rock would be Oppy's RAT engineering telemetry, such as the current draw or the grind time of the operation, and not amount of cuttings.

--Bill

"Poor man's" superres from the 2720 Tribulation/Solander 16 L6 frames:
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As usual, this isn't a true superres - all I've done is resample to double res, then register and average, to (dramatically) reduce jpeg noise.

I'd agree with Scott Maxwell's opinion on such a thing...

"*Yawn*."



-m

EDIT:



Haha, I love the multiple shadows in there. Very clean merge!

Is there enough control in the arm and enough brush left to sweep out the grind debris? I remember that the brush bristles were a bit "cattywumpus".

They have indeed done just that - infer hardness based on RAT performance. If you remember back in the early days - a berry was picked up mid-grind as a spike, and later caused the RAT to stall.

Tribulation L257
sols 2718 & 20

Click to view attachment

While fresh basalt is a pretty hard rock, the softness doesn't rule out basalt. If basalt is weathered or altered, especially in the presence of water, it can become quite soft. I think the light color of this rock pretty much eliminates it from having an overall basaltic composition, though the dark, angular rock fragments embedded in the breccia could very well be basalt. The minerals of basalt are very dark in color.

The dark blocks of a different breccia lying on top of the nearby hill look very much like basalt. The geology here is fascinating. I can't wait for Opportunity to explore more of Cape York and send back more pictures.



Bill: You are right about the RAT telemetry being the ultimate measure of the rock hardness, but it will be a while before that data will be available...and I won't know how to interpret it when the data is released. My comment on the rock's softness was based solely on depth of the grind. We know that the remaining life of the RAT is a resource the team is trying to conserve for the most important scientific targets, so I would be surprised if they instructed the rover to grind away on this first target without limits. To me, it looks like other soft rocks they have ground into.

I really appreciate that you post important information like the sol and the filters used in your images. Some people often neglect to provide that information, and that makes it difficult for others to follow up.

For sure. The surface we are looking at is the product of 3 bln years of deposition, weathering and erosion and each rock fragment tells a story. Some of these rocks are ejectite'd impactites.

There are going to be many profound papers generated from the data at this site.

I'm sure that they know precisely what the "hardness" of the rock is from the engineering data, which we in the p'nut gallery are not privy to. Just as they have an idea what mineral is represently by every "RGB color" we see in the Pancams. Even with seriously degraded IDD parts, geologists have made do with scratch plates, acid bottles and rock hammers and calibrated "TLAR"eyeballs for decades for mineral identification.

The first thing they are doing on Sol-2722 ("today") is making a FHazcam assessment of the RAT teeth("frhaz_RAT_bit_check_subframe") and getting ready to do chemistry ("front_haz_idd_apxs_doc").

Having snagged the post-grind Pancams of Salisbury1 from the 0:35 Data Express and done my preliminary oooh-ing and ahhh-ing, I'm hitting the sack again... yawnn

--Bill

Could they be obsidian in a perlite matrix?

Couldn't get my beauty rest, I ended up working on the new images. Note the implication of different mineralogy-- the RAT cuttings are purplish or gray, instead of the usual ochre or blue.







--Bill

Here's an attempt at a color flicker pair. L257, R21(synthesized green), animated GIF, anaglyph

All that different to earlier grindings?

http://marsrovers.jpl.nasa.gov/gallery/pre...1-B041R1_br.jpg

Good example. This is the first RAT done in Eagle Crater on Sol-36.

More difference than 21km and 2+ Billion years...

--Bill

It would be interesting to compile a sequence of images showing the RAT holes at different dates - right now we are getting that small circle inside the larger one, which was not seen in the first hole. When did it start looking like that?

Phil

My guess is, that's what happens when the two grinding wheels are not rotated around each other.

"Two grinding wheels rotate at high speeds. These wheels also rotate around each other at a much slower speed so that the two grinding wheels sweep the entire cutting area."
http://marsrover.nasa.gov/mission/spacecraft_instru_rat.html

It may be a result of the damage to the RAT brush. At the very least it's not new. I see similar circle-within-a-circle patterns in this RAT hole from Sol 2513.

The circle-within-a-circle is how the RAT operates. The carbide cutters are on an arm that moves around in a cyclical motion. You can see how it works in the images at the Athena site (the link to the "Honeywell Robotics" RAT site is dead):

http://athena.cornell.edu/the_mission/ins_rat.html

After the grind is done the brush is supposed to clear away the cuttings but the brush is kaflooey...


You can get an idea of how well it works from this animation:

http://images.spaceref.com/news/2004/rover.armspin.mov


--Bill

Interesting responses! But that's why it would be interesting to collect RAT images throughout the mission to see how the holes have varied in appearance. Anyone? (I don't have time right now)

Phil

We are thinking about doing that sometime soon. There was considerable debate among the SOWG whether or not the extra rubbage in there would contaminate the exposed core of the rock. We've got ground in the loop to look at some things tomorrow and may try another brush+APXS.

Soonest we can count on boogeying on out of the Chesterlake area is... Friday? We'll be hitting nominal sols soon and it'll be day in day out for two weeks.

-m

This page might be useful for you, Phil...

http://marswatch.astro.cornell.edu/pancam_...ges/merges.html

... and even more useful for the person who makes the comparison image! Actually I think straight pancam images would be easier to use for this.

Phil

Ok, just thought it was worth a look for you. I'll have a delve into the archives tomorrow.

It's a great site, Stu! I just don't have time to look at this question right now - up to my ears in Itokawa problems.

Phil

Brushing may not make a difference-- look at the surface of the pre-RAT IDD site and it looks really sand-blasted clean. Brushing off the cuttings would be critical if the surface were weathered or dust-covered. Though it would be nice to see what the clean, grinded surface looks like.

AFAIK, the next known important site is in the area of the CRISM phyllosilicate signature around that summit crater ~300m NE. And, of course, important sights seen along the way...

--Bill

A composite pancam/microscope image of the recent RAT hole in 'Chester Lake'
pancam L456 sol 2721
microscope sol 2719 (jvandriel's image from here)

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That's certainly a possibility, Fran. I didn't think of that, but I suppose it could be obsidian in perlite. I don't have a lot of experience with volcanic glasses, but the few times I saw such rocks in the field, the obsidian inclusions were typically rounded and not angular like these. That's an interesting suggestion that I will have to consider. I have to wonder, though, would we expect to see glasses in rocks that are so old, or would they have devitrified after all this time, perhaps leading to the formation of clay minerals?

I'm not familiar with that mineral, but AFAIK perlite is a volcanic glass (obsidian) that is hydrated and when heated, it expands producing a light weight, light-colored material. From the few pictures I've found it looks like a medium-greyish rock with a pearly luster. The diagnostic feature is that it expands greatly when heated.

What have we seen here that looks like perlite? And how was it identified? It would be good to find a perlite since that would imply an impact melt that was hydrated because it was created from a wet parent material.

Enquiring minds need to know...

--Bill

"Perlite" (I assume it's the same stuff) is a soil conditioner commonly used in hydroponic gardening. It's very soft - you can grind it between your fingers, and I think even under today's martian environmental conditions, exposed perlite would have long since eroded away from just the rarefied effects of the wind. I suppose there might be deposits of it buried underground dating from the noachian era, but very unlikely that it could be mined with just a RAT. (I'm no geologist - please let me know if this is a completely different substance I am thinking of.)

A break from mineralogy: the cyclops is crying.
http://qt.exploratorium.edu/mars/opportuni...19P2285L2M2.JPG
The crater seems to collect and 'focus' the downslope streak.

Great view!

Phil

Ah is a gee-ologist but 40 years outta school. "Perlite", as far as I can tell, is a manmade product created by heating a hydrated obsidian to some 1600*F where the volcanic glass softens and the entrained water causes it to"foam up" and expand. And as far as I can tell, hydrated obsidian, the mineral, is also (and possibly informally) called "perlite". I don't think that the manmade commercial soil additive occurs in natural deposits anywhere. However, I wonder if the "hydrated obsidian" could refer to an impact melt created from a water-saturated source material. With certain temperatures/pressures/timeframes I can see this as "possible".

Over time, a glass can weather or degrade from a "glassy" form to a "crystalline" form, a process called "devitrification". In obsidian samples, this is seen as "snowflake obsidian". It could devitrify into a smectite or a clay mineral, but I've seen no suggestions at Salisbury1 of devitrification of the impact melt.

And, picking nits, obsidian is a siliceous rhyolytic glass which is not compatible with the mafic (silica-poor) basalts we see in this region of Mars, so we're looking for glass of basaltic composition, such as a tachylite.

Why get worked up this much about a volcanic glass? It may well be the best way to do a comparative study of the creation and weathering of impact melt (impact glass) on Mars.

--Bill

Here's an L2/5/7 composite from sol 2718, part of the 'big pan'. There are some subtlety fascinating variations in colour coming through.

Click to view attachment

At this point, even though it appears likely, we really don't know if we are seeing impact melts or not. But the point I was trying to make regarding devitrification was that after about 4 billion years any volcanic glass that may have existed should have had ample time to devitrify. Have you ever seen a Precambrian glass?


I understand that we are expecting to see basaltic rocks here, but we don't "know" that all of the rocks here are mafic. Some silicic volcanics would probably be a very exciting discovery on Mars, but I was simply acknowledging Fran's observation that the current science target does resemble an outcrop of obsidian in a perlite matrix.

We have to remember that we are among the first geologists from our planet to have had the opportunity to explore the rocks of another. We should expect to be surprised as often as we find things that are familiar.

N.B: The perlite used in hydroponics and soil conditioning may be derived from the rock known as perlite, but it is not the same thing.

Good points, Tom.

I think we are seeing glasses (impact melts) here-- we certainly see impact breccias with many angular clasts that have a vitreous appearance. If not from Endeavour, then from any of the several other impacts evident in the area.

We don't see that many Precambrian glasses here on Earth. But PC rocks here have been buried, metamorphosed, tectonicizated and generally weathered in a warm and wet oxidizing environment. On Mars, they've been in dry storage for megamillenia (by comparison), so I think that a glass would stay glassy much longer. But this is the first example we've been of the type, so who knows...

Google in usually your friend, but in this case was a tangle of ambiguity. Most of the hits for "perlite" were for the garden soil additive with loose pointers towards the volcanic glass mineral. And I've not seen my copy of Dana for decades...

What was the source of that "perlite" photo you showed? I tried to back my way out through the "bigcache.googleapis.com" URL but I got 404'd.

Nice new Pancams of site "Chester Lake2" this AM, and the tracking web suggests more MI's upcoming with soem APXS work. Then, I've heard, Oppy'll be moving on by the weekend.

These are interesting times...

--Bill

Sol 2722 Front Hazcam.
The RAT is still working.

Jan van Driel

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It can still be your friend if you Google "perlite ore".

Here's one concise description from a company whose claim to fame is owning both ore mining and processing facilities:
"Perlite Ore is formed by magmatic ("liquid rock") processes, usually in "domes",that over geologic time periods entrap water into the Perlite matrix. The mechanism through which this occurs is not completely understood, however, it is this entrapped water which gives perlite ore it's unique ability to "Pop" under proper high temperature conditions."

As there are still missing data I haven't tried too hard to perfect this, but the the view is so astounding that I can't keep this preliminary version to myself!



James

Absolutely gorgeous James! I've been trying to make the same view but can't get the ends to behave, or the colours to all blend, so I've gone with the central section and trying to bring out subtle shades and features in the central dome...

Click to view attachment

Both are spectacular! Thanks.

Phil

wowie! What a spectacular view.

Q- do we see haze in the distance? It looks so much like the San Fernando Valley, my brain computes an earth analog :-)

Apologies if this has already been discussed, I searched for "haze" in this topic and the Cape York thread.

I did an image search for "perlite obsidian" and found some photos of obsidian in perlite. That image I linked to came from this guy's Panoramio album.

Ah, good search. Being an imprecise name, I didn't use "perlite" with "obsidian" in the same search term.

Did dig up a couple of references via the image search:

The hydration and alteration of perlite and rhyolite
http://jgs.lyellcollection.org/content/166/5/895.abstract

and




--Bill

I don't know a thing how you all get the pictures and "driving data" from (I think) exploritorium. But, is there a way to see the results of the APXS that we're doing on Chester Lake from that data? Be great to know what the results of the Zinc levels and discuss it here.

No, sorry! You have to wait for the APXS team to announce something.

Phil

APXS = real science! There's no way the team would release the important stuff like that before they had a chance to publish the results themselves.

The pictures have relatively little science value (at least it's unlikely anyone would scoop the team and publish something based on the pics alone). That's why we get to see the pictures in real time.

Absolutely - actually it's dust hanging in the air. But it's been slowly improving as we head into winter. Check this post.

I think Jim Bell would beg to differ, as would most of the geologists on the team However it's true that pictures alone rarely form the basis of a scientific paper. In any case the scientific value of the pictures is degraded by them being piped to the Web without calibration, auto-stretched, and JPEG-compressed, and one would be an idiot to write a scientific paper based on these raw JPEGs. Although I don't know for certain, I'd hazard a guess that uncalibrated APXS data would be uninterpretable.

True. It would be next to impossible to identify mineral makeup from pancam using the raw images from the web over only 11 wavelengths. Deconvolving spectra would be a huge challenge and would require data not available such as the CCD and electronics temperatures when the image was taken to enable proper calibration. The calibration target chips included hematite and goethite powder and were conditioned with UV exposure before launch, but after all this time could well have suffered from UV deterioration. I would assume that Jim Bell would have ensured laboratory spectra from expected minerals /combinations over expected temperature ranges using the actual deployed pancam to provide comnparative baselines. Certainly out of the amateur league.

But the Pancam and MI provide a huge amount of visual data and it is the correlation of all data that enables the production of the absolutely outstanding science papers we have become used to.

Three years ago today (if I've read the dates right), on sol 1661, Oppy paused in her trek around the edge of Victoria Crater, stopping just in front of a small crater called "Sputnik", and we all marvelled at the incredible vista before her: the great crater's capes and bays stretched away on all sides, its crumbling cliffs and dust-rippled floor all fighting for our attention. Oppy sent back three pictures of "Sputnik" which, when joined together, looked like this...

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On the far horizon were a few barely-there bumps - the hills marking the rim of a huge crater called "Endeavour", an enormous hole in the ground that was so far away that even thinking of trying to drive to it was foolish; such a journey would take years, years, and require the rover - which had already exceded all expectations - to cross a vast area of unforgiving desert. Oppy wouldn't get even halfway, surely...

Three years later...

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