. . . and here is the right part of the sol 158 panorama

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Sol 158 anaglyph:
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Sol 159 Incoming?

Probably not, but it would be cool if it was
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It is an incoming. Most likely an incoming cosmic ray

A very interesting question that has been on my mind.

Knowing the pixel size of the Mastcam-Z sensors, the stereo baseline, the "toe-in" angle, and the focus length, it is possible to calculate size and distance of objects from photos that were taken at the same time by both cameras.
After testing some derived formula with the calibration target no. 1 on the rover (which gave a correct diameter of the rings around the gnonom), I looked for some round grains and pebbles to measure and found this (see center of dark circles):

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(colors enhanced)

The small shiny sphere has a diameter of about 3.6 mm. There seems to be a tiny hole on the side.
The oblique distance to the Mastcam-Z is about 2.46 m. This means that the distance between the sphere and the nadir of the mast is 1.25 m, so it is quite close to the rover.
What could that be? A ball of Persevance's ball bearings? Hopefully not. Or something original Marsian? Maybe a microtektite?

That is amazing.
I would guess a microtektite. Or a small concretion, rather like the Meridiani Blueberries.
In either case, likely ejected from a remote impact site.
At least this gives us a feeling of scale for the other components of this sparse lag deposit.

--Bill

WATSON images of an abraded and cleaned target on a CF-Fr paver during Sol 160
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Interesting weathering of that tick surface. Especially those "rusted out" looking clasts.

--Bill

Anaglyph of a "paver stone" after abrasion and cleaning on sol 160, made from Sherloc Watson camera images

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A closer look at the abraided target with WATSON, and a mosaic of overlapping SHERLOC ACI frames from sol 161.
Lots more images on the servers
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Possible olivine dissolution?

Weathering in a moist environment.

--Bill

Weathering of olivine would be one pathway to the olivine / Mg carbonate mineralogy.

A closer look at a section of the abraided surface with WATSON on sol 161: link

The closer look by Watson on sol 161, here with enhanced color contrast

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I’m sticking with my rip-up clast conglomerate, sporting granule to pebble sized clasts, with some kind of patchy cement. These kinds of facies are common in dryland/ephemeral fluvial successions. They form during channel incision and bank erosion, and are sorted and organized into sheets and bars during flood events. This would explain the mix of rock types, including possible nodules and concretions, swept from the drainage basin feeding the delta distributary system.

That would explain the chaotic nature of this lithology. Soon we'll have an idea of the mineralogy here.

Tim, given the position within the crater are you suggesting a deposition during the later stages of delta formation or an early deposition in a closed system, prior to the spread of the delta, filling of the lake and breach in the Eastern wall?

Sol 162 SuperCam RMI with Mastcam-Z context from sol 158

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First cored sample acquired on sol 164 seen in this Hazcam frame

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To help focus, here is a close-up of one of the weathered out, irregular shaped, rather deep areas which allow to look below the abrasion surface. To me the abundance of dark green, relatively large minerals at the surface stands out as well as the very dark, very fine grained matrix below the surface. The bright grains in places mantle the dark green minerals and I think could be interpreted as alteration products, of less stable mineralogies, such as mafic minerals. I cannot help it but the dark green minerals look crystalline to me, very angular and with reflective facets. The very fine grained, dark matrix embeds small green and bright particles. The perhaps (sub)microscopic grain size of the matrix could result from muddy (re-)deposition in a clastic interpretation but could also represent a glassy, cryptocrystalline material in a volcanic interpretation. In a sedimentary scenario the very dark color may require further explanation given a lack of organic carbon. At the base of the cavity, there is brighter material indicating perhaps continued alteration after formation of the cavity, or/and circulating fluids.

There is a possibility that we are in a mixed volcanic/clastic sequence given that we can clearly observe horizontal layering of in places rather thin beds, as well as strong indicators for rocks of magmatic origin, in the same sequence. Such volcaniclastic sequences are not typically associated with mafic volcanism but it is unclear how that association applies to a lacustrine environment on early Mars.

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Coring did not go as planned

Early pics and data show a successful drill hole, but no sample in the tube

News release: https://mars.nasa.gov/news/9007/nasas-perse...mpling-attempt/

The greenish crystals are probably olivine Paul transported (as tdemko indicated) from the high olivine unit of the catchment. Olivine normally consists of a mix of Mg and Fe silicates and is very susceptible to chemical erosion. Add a high CO2 atmosphere to the water and Mg carbonate can result as well as Fe oxides/hydroxide. The dark components could be anything from ferric mud to olivine in the process of dissolution (the attractive green presentation morphs to a dark, dirty colour).

Sometimes you do lose the core. I feared that when I saw cuttings to the top of the hole. The rock may have been soft, friable and weathered.

--Bill

Imaging the sample hole with the SHERLOC WATSON imager Sol 165. (Raw images, only added annotations)
Illuminated with sunlight and LED lights (see timestamps)
No sign of the core (yet), but the tailings have not been blown away yet
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EDIT: There are a series of WATSON images on sol 166 of the underside of the rover.

Maybe they are checking to see if the core was ejected from the sample tube?

Assuming this is a search for the errant core My old eyes did not find a core...
But it's more likely a WATSON wheel check as they've driven just over mile (1631 meters)
Only 8 WATSON images so far. Roughly assembled in MS-ICE. The wheels look in excellent shape...

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By core, you mean the regolith material that was expected to be in the sample tube, correct? Making sure that you don't mean another tube that would be in the now empty tube.

From the images of the hole, it appears material was removed, and the contents of the sample tube didn't just fall back into the hole as the sample core was lifted from the hole. I wonder if we'll get a series of images of the ground beneath the path of the sampling head for a pile or trail of regolith. It's gotta be somewhere.

Gotta admit, this has me worried. The fact that the JPL press release said this had never been seen in testing on Earth means there's something unexpected in at least this spot of Martian surface.

These cores they drill, are they or are they not solid plugs of rock ?, if they are solid how is the bottom part broken off from the rock they are drilling ?

They can be solid. I'm not sure how regolith is sampled, there may be multiple bit types [edit: yes, there are six coring bits, a regolith bit, and 2 abrading bits, see Mars 2020 Rover Adaptive Caching Assembly: Caching Martian Samples for Potential Earth Return, in the 45th AMS conference proceedings]. Unfortunately the SSR paper about the SCS is paywalled. See https://trs.jpl.nasa.gov/bitstream/handle/2...L%2317-1087.pdf for some discussion of the core breakoff mechanism (page 5.)

There are lots of references but many are old and I'm not sure what the system that flew ended up looking like.

As I understand it, and that much of this is like terrestrial core drilling, a cylindrical bit with "diamond teeth" drills an annulus into the rock, and an inner cylindrical sample tube catches the cylindrical rock core within the annulus created by the coring bit. The sample tube extracts the core when it and the voting bit are removed. In theory, the rock core breaks off at a bedding plane and the whole core is extracted. But not always.
That was clear as mud. Lemme find a "core drilling 101" page and post a link.
The first view of the core hole via a Hazcam left me with the impression that the hole was filled with cuttings to the top and the sample tube didn't catch the core. This latest Watson pic looks like an empty hole with the core extracted.
We'll know more later.

--Bill

I'm pretty sure that the final design is what Honeybee called "One Breakoff System One Core (OBSOC)" in https://www.hou.usra.edu/meetings/lpsc2014/pdf/1168.pdf if that helps.

My take on the WATSON mosaic of sol 166. I think other pictures will arrive to complete the left part of the mosaic.

If it is the Honeybee core drill, it's good.

--Bill

I have access to the SSR paper. After a very quick look at it, 1) the pile of powder surrounding the drill hole is expected and there are flutes to channel the powder created during the drilling out of the hole, 2) there is a volume probe that is inserted inside the sample tube after a collection attempt to determine the volume collected (this may be well known here, but it was new to me), 3) the entire sample handling and caching system is hugely complex and my hat is off to the engineers who built and test it.

Lake basin fills often form a "sandwich": fluvial-lacustrine-fluvial, recording the early incursion of the water and sediment via rivers and streams, the rise of the lake level, and then the shallowing and eventual fill. As you mentioned, these stages can also correspond to the type of hydrologic conditions: open or closed. Lake basin fills record that fluctuations between and open and closed hydrology are called balanced filled. The ultimate controls are the rate of generating accommodation (the space available to put water and sediment) and the flux of water and sediment entering into the basin.

I think if the rocks in question are intraclast conglomerates, they could be part of the early fluvial part of the sandwich, or the final last gasp fluvial deposits formed as the sill was breached, draining the last lake. Either setting would be conducive to erosion and incision in the drainage basin.

Some processed and enhanced images of the drilling site
1) and 2) Sol 165 Sherloc Watson camera
3) Sol 166 Mastcam-Z anaglyph
4) Sol 166 Mastcam-Z right eye multispectral (channels 0 to 6) principal components. The spectral reflectance of the abraded (weathered?) material differs significantly from that of the drilled powder.

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Just a hypothesis: Maybe the rock is so porous and brittle that it breaks into pieces during drilling. The pieces rotate together with the bit.
The lowest pieces in each case can be successively moved by centrifugal force between the teeth of the drill, are further crushed there,
and then moved upward outside of the bit by the bit flutes out of the hole, forming the pile of drill cuttings there.
That is, the pile may be what the core should be (just a hypothesis).

I had suspected the same about the fate of the core. If it was extracted and then fell out it would probably be visible in the front hazcam or other images by now.

Phil

Sol 167 SuperCam
Kind of strange: the "powder" around the borehole seems to be quite cohesive and looks more like mud in some places.
Even two laser blasts couldn't destroy the thin edge of the pile.
I don't believe that the rover brought a supply of drilling fluid with it to Mars.

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Does the pile really look like it has enough volume to equal that of the hole?

I thought about that, and am certain the Percy team has, too, but I wonder if the packing density would vary by rock/soil* type, and hence make this unreliable.

(*Yeah, I know there's no real soil except here on Terra, but it's such a convenient term and I'm not sure if regolith always applies to the surface materials.)

Is there any significance to the larger fragments around the perimeter, assumed to be from the initial phase of the drilling and the subsequent fine powder?

When drilling (even core drilling) the abraded ground-up rock has a certain "bulking factor", the pile of drill cuttings can increase in volume over the hole (or annulus), so the guesstimated volume of the cuttings vs the volume of the drilled core annulus doesn't look odd. But assuming that the core wasn't dropped somewhere volumes might not add up. I'm sure that the people looking into this have calculated volumes of the cuttings pile and volumes of the drill hole and compared. It might be that the rock was so weathered and friable that it was ejected with the drill cuttings. The telling parameter will be the drilling pressure needed to advance the core drill.
I'd assume that the larger fragments around the edge of the cuttings were the last removed from the hole.

Drive during Sol 168 to a rock strewn ridge south(?) of the drill site
The new location has some of those layered rocks imaged from the drill site.
Roughly assembled/processed 2-tile L-Navcam mosaic.
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Link to a detailed description of the capture drill and methodology.

https://ntrs.nasa.gov/api/citations/2015000...20150004061.pdf

I believe, as I alluded to upthread, that this is a slightly out-of-date description, not exactly what they ended up flying. This paper describes what Honeybee called One Bit One Core (OBOC).

That said, it does capture the basic idea. There are three types of bits, one for solid rock cores, one for loose soil or regolith, and one for abrading (doesn't capture a sample). AFAIK, it's the first that resulted in the missing core.

Question: can they reuse the tube they tried to fill, or is it toast?

AFAIK (and strongly implied by the press release) the tube has been sealed and stored, so no reuse. The mechanism is complex enough without expecting it to be able to run backwards too.

A mosaic of two RMI pictures in its context on sol 168 (MCZ mosaic also taken on sol 168).

The team have just published a mission update, written by Louise Jandura, Chief Engineer for Sampling & Caching at NASA/JPL
'Assessing Perseverance's First Sample Attempt' Link
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Sol 169, a circular view of the location. We still don't have a full panorama for sol 168.

Phil

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