Gigapan - PERSEVERANCE 642-W
© NASA/JPL-Caltech/MSSS/ASU/NeV-T

Gigapan - PERSEVERANCE 657
© NASA/JPL-Caltech/MSSS/ASU/NeV-T

Gigapan - PERSEVERANCE 644
© NASA/JPL-Caltech/MSSS/ASU/NeV-T

Gigapan - PERSEVERANCE 646-W
© NASA/JPL-Caltech/MSSS/ASU/NeV-T

Your work is amazing TAU -- thank you

I agree. But so is yours, Neville.

Phil

Thanks Phil I try my best

Sol 667, from Paul's images.

Phil

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Perseverance has been on Mars for one full Mars year.

Phil

SOL 666 - Tube Drop #4
GIF - Deep Histo
Notes:
* a rock in the right wheel
* much sand in the middle wheels
* an older tube drop -- to the left of the upper right wheel
* reduce (6x) to fit
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Thanks for the animation. It does look like sand in the mid wheels in the enhanced frame, but looking at your mosaic in this post from 5 sols earlier those wheels look clean.

FredK
here is a higher resolution of the enhanced frame
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"looking at your mosaic in this post from 5 sols earlier those wheels look clean. "

Interesting... that sol 661 image - yes, the middle wheels do look clean, but look at the wheel on the far left. And then look at the sol 666 mosaic again - actually most of the wheels look like they may be carrying some sand. It's probably ephemeral... drive through a drift and pick up some sand, a few sols later it's gone. The front wheels on sol 666 seem to be carrying sand with a bit of a slope to it.

Phil

Sol 667 panorama, along with a large version derived from Paul's tiled NavCams and pointing info.

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We can watch the changing landscape in this extended drive animation starting back on Sol 394 including some of the traverse to the delta. PDS imagery is now used between Sols 436 and 539.

Fifth rock sample was dropped off on sol 668 (6 January, 2023). This sample is from Brac rock, an igneous rock altered by water several times.

Sol 668 SuperCam Remote Micro-Imager mosaic with "marsonaut" for scale

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Sol 668 Mastcam-Z context and sol 667 Navcam context for the sol 668 SuperCam RMI mosaic in the preceding post

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We've been seeing great views of in situ outcrops of poorly sorted coarse-grained units in several places, just like in these awesome pans by tau (with the very helpful marsonaut for scale!). The coarse-grained (cobble-boulder) units are always intercalated with finer-grained sandy strata, above and below, sometimes filling channel-like scours, and as part of inclined delta foreset strata, like here. The presence of these units is telling us something about the nature of the sediment discharge that built the delta: delta front foresets are built by the failure of mouthbars that accumulated at the ends of the fluvial/distributary channels where they entered the standing water in the lake, or by direct underflow (hyperpycnal flow) from the channel and down the delta front. During turbulent flows, grain sizes are sorted during bedload (sand and gravel) and suspended load (clay and silt) transport in the fluvial channels. Most gravel, and a lot of sand, is deposited somewhere in the fluvial system or delta plain, in the higher slope reaches, while the remaining sand is finally deposited in mouthbars. These mouthbars grow until they fail down the delta front as sediment gravity flows, or divert the distributary channel to either side, or generate an avulsion somewhere upstream via a backwater effect. The sand in mouthbars is further sorted after they fail during transport in sediment gravity flows, typically depositing the kind of sandy, fining-upward units (turbidites) we see making up most of the inclined delta front strata in the images. The coarser-grained units must be from a very different type of depositional process: debris flows. Instead of turbulent flows, where the mud, sand, and gravel are segregated into bedload and suspended load, debris flows are comprised of a much higher sediment/water, move as plastic or plug-like flows, and there is no turbulence to sort grain sizes. Large clasts can float in or on a finer-grained matrix, and the resulting deposits (debrites) end up very poorly sorted. Of course, there are gradations of and between turbidites and debrites, and the two processes can be related (a following turbidity current after a debris flow, for example). In any case, it looks like the Jezero delta lobes were built by both turbulent flood discharge and debris flow events.

SOL 668 Tube Drop #5
Enhanced Deep-Histo
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Sol 670, from Paul's images.

Phil

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Sixth rock sample was dropped off on sol 672 (10 January, 2023). This sample is the first collected by Perseverance, from Rochette igneous rock back in September 2021.

Sol 669 SuperCam RMI mosaic with Mastcam-Z context and left eye filters 1 to 6 multispectral image.
The size of the small white stone is about 1 cm, the size of the larger dark shiny stone about 4 cm.
Both show remnants of a purple coating, which can also be discerned well on the multispectral image.

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I haven't seen anything on the purple coatings since the last LSPC (attached). Hopefully someone will have delved into this and present at the forthcoming LSPC. But if the attached paper is correct that white rock must be extremely durable.

https://www.hou.usra.edu/meetings/lpsc2022/pdf/2346.pdf

Gigapan - PERSEVERANCE 670
© NASA/JPL-Caltech/MSSS/ASU/NeV-T

Seventh rock sample was dropped off on sol 675 (13 January, 2023). This sample, named Bearwallow, was collected from Wildcat Ridge mudstone.

Sol 674 panorama, along with a large version derived from Paul's tiled NavCams and pointing info. Net motion is slightly north of east since Sol 667.

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We can watch the changing landscape in this extended drive animation from Sol 394 to the present. Some Sols utilize PDS imagery.

Sol 676 SuperCam Remote Micro-Imager mosaic and sol 674 Navcam context

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Sol 676 Mastcam-Z context for the SuperCam Remote Micro-Imager mosaic in the preceding post,
Mastcam-Z left eye filters 1 to 6 multispectral image, and anaglyph

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Sol 677 SuperCam Remote Micro-Imager mosaic and its sol 674 Navcam context.
It is probably a vesicular volcanic rock, although at first glance it resembles an iron meteorite.

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Sol 677 SuperCam RMI mosaic no. 2 with Mastcam-Z context and Mastcam-Z left eye filters 1 to 6 multispectral principal components

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Thank you, tdemko. That is my intention, an aid to better perceive the actual size.
I am surprised every time that the rocks are much larger than they appear at first sight without scale.
I hope my calculations of the scale are about right.

Here is sol 677 SuperCam RMI mosaic no. 3 with "marsonaut" for scale

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Sol 676 Mastcam-Z and sol 667 Navcam context for the preceding Supercam RMI mosaic

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Sol 676 SuperCam Remote Micro-Imager mosaic no. 2 with "marsonaut" for scale and sol 667 Navcam context

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Your scale looks about right to me. Using the distance for that sol and the mastcam fov I find your marsonaut to be just a bit shorter than 2 metres.

Thank you, fredk, for checking the scale.
I assumed a hight of 1.8 m for the marsonaut in the calculation.

Sol 678 circular view and close-up using Paul's images.

Phil

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Something that the Apollo 14 astronauts found out as they got lost seeking Cone Crater was that our perception that is adapted to the Earth is not necessarily adapted to another world. We are used to humidity (etc.) decreasing contrast as a function of distance, which makes distant objects look gray-er than nearby objects, as well as smaller. On Mars, dust may play a similar role, but the parameters are certainly different. (Of course, humidity and illumination are far from constant on Earth.) Which is just to say, we can't trust our usual judgments on another world, including the ones that we've come to take for granted.

That's all very true, but I think the problem we all face here is a bit different. We see the amazing detail in an image and we forget that it's zoomed in so much that the spatial context isn't there to help us. Compare an image of a rock with a much broader mosaic, when we get one, and it helps to see how large or small the feature really is.

Phil

Could there be even more to it? When I look at the RMI mosaic in tau's post above I can easily imagine those rocks being centimetre-scale rather than the metre scale we know they are (that's what made me want to check the scale). To this non-geologist's eyes they look much like centimetre-scale rocks we've seen elsewhere on Mars.

It makes me wonder if there's something about the geological processes or materials here that's very different from elsewhere.

Thick bedding tends to indicate a stable depositional environment.

In some fine-grained rocks, yes. The vast range in grain size (mud to boulders) in these successions suggests that there were proportionally large changes in sediment carrying capacity of the flows, and as I mentioned before, different sediment/water concentrations with related differences in the turbulence and rheology of the flows. What does suggest some stability in the environment is the architecture of the delta lobes, in that they have a very well defined foreset/topset organization, indicating progradation into a lake that had a fairly consistent lake level. However, in several of the larger outcrops, there is some evidence of deposition at both lower and higher lake levels, but still characterized by well-defined foreset/topset geometry. The stratal relationship between adjacent lobe packages also indicates that avulsion was an important process. We are getting some very good cross-sectional views of lobe packages (in depositional dip and strike) in which we can start to estimate their areal geometry, too, along with the estimating the water depth from the foreset height.

This figure has some good examples of the internal geometries of delta lobes (from this paper: Quantitative characterization of the sedimentary architecture of Gilbert-type deltas).

Sol 680 SuperCam Remote Micro-Imager mosaic with Mastcam-Z context, Mastcam-Z left eye filters 1 to 6 multispectral image, and sol 678 Navcam context

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Is there any information on the composition of these light rocks? Given Curiosity's discovery of light rocks containing feldspar and silicon oxide could these be similar composition, potentially felsic?

Eighth rock sample was dropped off on sol 680 (18 January 2023). This is a sandstone called "Skyland" collected on "Skinner Ridge" rock.

Ninth rock sample dropped off on sol 682 (January 20, 2023). This one is from "Sid" igneous rock. One more to go!

Sol 678 panorama, along with a large version derived from Paul's tiled NavCams and pointing info.

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We can watch the changing landscape in this extended drive animation from Sol 394 to the present. Some Sols utilize PDS imagery.

A rock with patchy remains of a purple coating in a sol 682 SuperCam Remote Micro-Imager mosaic
with Mastcam-Z context and Mastcam-Z left eye filters 1 to 6 multispectral image.

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As already mentioned earlier, there exists an iron oxide pigment with the same color as the purple coatings.
It has the strange name Caput mortuum. The other name of this pigment is a nice coincidence, it is . . . Mars or Mars violet.

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Here is a link to the paper "Characterization of the Caput Mortuum purple hematite pigment and synthesis of a modern analogue".
Could it have some relevance to the purple rock coatings on planet Mars?
From the abstract:
Unfortunately, most of the text is behind a paywall.
Could anyone with access to the entire content provide more information about the process that produces the purple color?

That is interesting Tau, given that Curiosity determined that the purple coatings discovered in Gale crater in 2016 were enriched in hematite and hydrogen. Perseverance confirmed hydrogen and iron oxide. But is seems more complex than just particle size. The link provides one pathway to purple hematite but the temperature requirement makes it problematic for Mars. There is also the 'natural' powdered Blue Ridge Violet Hematite (Virginia) which if you squint is kind of purplish/violet.

https://reader.elsevier.com/reader/sd/pii/S...=20230122025938

This (dense, but understandable) paper shows that there are several ways to get purple hues in hematite compounds, but all work to control the position of the ~545 nm absorption band (more purple at longer, lower energy wavelengths):

THE VISIBLE DIFFUSE REFLECTANCE SPECTRUM IN RELATION TO THE COLOR AND CRYSTAL PROPERTIES OF HEMATITE

These controls include Al-substitution and specific surface area (essentially proportional to grain size). Both could certainly be affecting the hue of these coatings.

As I remember it Perseverance also detected a degree of Mg enrichment which throws possible ambient temperature phase transformation effects (ie. maghemite) into the mix.