Unfortunate that we can't retain this small fragment when we gather the next core. We'd have two locations sampled in a single tube.
Also, you weren't wrong about seeing the metallic glint from the bottom of the tube, as it turns out.
The drilling process was seemingly not the smoothest:
Difficult to tell from CacheCam if the sample tube is full, and we have no animation of the drilling process as yet. Stay tuned!
Did this short drive really take 1 hour? I know Percy can move faster than that, especially when Ken Farley is cracking the whip...
That wavy boundary on the left is certainly groovy.
Or should I say that the groovy boundary is wavy?
These rocks are so damned weak that even Mars couldn't sew them up straight.
I hope I'm better at geology than poetry.
Ah yes, I saw that in pre-print. For a moment I thought this was the paper about the clay-rich/high-aluminum white rocks down in the crater, but yeah, this is some fundamental work by Kathir et al., with very nice figures to boot. This quote has me laughing right now:
The Noachian basement unit of the Jezero watershed unit is enriched in Fe/Mg-smectites, but we have found no float rocks with these compositions. This suggests that Fe/Mg-smectite-rich outcrops are friable, poorly lithified, and not well-cemented, and thus less resistant to erosion.
LOL You don't say... now where have I seen rocks like that recently? 😆
For reference, the rover position on sol 1549 is just a few metres west of abrasion patch #38:
I've marked with a red "x" the four locations on the rim where we've failed to abrade or sample so far. (Sorry about the map quality, it's a work in progress...)
Hmmm. Very nearly back to the site of abrasion patch #38, I see. I wondered if they would drive the rover to the nearest geologic contact, after seeing all the difficulty we've been having in the clay-bearing zone. Patch 38 fractured badly, too, but at least we were actually able to make the abrasion.
This mission really has seen a night and day difference since we summited the rim toward the end of 2024. I was taken aback last (Earth) year at seeing how quickly the science team was driving Percy up the inner rim, but now? The traverse map on the outer rim looks closer to the path a human geologist would take when learning a field site - learning the lay of the land, then back and forth, stopping for detailed work. And it's summer here at the field site, too. After all that this rover has seen and done in 4 Earth years, I really wouldn't have imagined how new and invigorating this crater rim campaign would be. So much to see, in such a small area...
Yep. I am smrt. (Thanks, Paul!)
Three sols after the first (messy, unsuccessful) attempt to abrade another rock in this clay-bearing region of the crater rim, Percy has made a second attempt, less than a metre away.
This target seems not to have fractured and broken as quickly and easily as the previous stuff, but this latest attempt ended after only 13 minutes - shorter than the usual 15-25 minutes required at other abrasion sites, but longer than the previous one, which ended after only 10 minutes. I'm wondering if the rover was programmed to use less force with this abrasion; if so, the results so far are not encouraging.
Mars is hard. Even when it's not.
Sol 1547 - They're taking another poke at the outcrop, just centimetres away from the last target:
I'll cheat, rather than taking the bet. 😁
The SHERLOC team usually takes two images of a target before abrading (the close-up at a ~5 cm standoff, the wide-angle at ~25 cm), which is what this shot (close-up) and this shot (wide-angle), taken on Sol 1545, appear to be.
On casual inspection, I don't see much difference between this new possible target and the one that didn't work out on 1544 (close-up here, wide-angle here), but... I'd really like to abrade this stuff, too. This clay-bearing unit we seem to be driving on makes a nice contrast with the failed abrasion site higher up on the rim, where the rock was actually too hard to abrade, and sure seems different from the almost rhythmic material down on the flat...
Still can't believe we've been set free to rove on Nili Planum.
Aside from those already listed in the other post, there's only one other patch for which I don't have a given name (#34, Sol 1395), so that's a total of four.
The drilling/abrasion tools on Curiosity and the MER twins have given us a good idea of the rock strength encountered by those rovers, but I haven't seen much research on the subject for Percy as yet. It's a little frustrating - that's a stat I'd like to include when writing up the different patches, it really would help tell a story. I know the mission has enough "drill parameter" data to make an interesting tale...
From the blog:
Perseverance performed an initial toe-dip into this clay-bearing unit back in April, creating the Strong Island abrasion patch, before returning back upslope to Witch Hazel Hill to sample some spherule-bearing rocks. Since then, Perseverance has started exploring this clay-bearing unit more extensively, creating the Laknes abrasion on Sol 1526.
Allow me to add, for your viewing pleasure:
36 - Slants River
37 - Name not given - but my nickname for it is "Subtle Scales"
38 - Strong Island
39 - Hare Bay
40 - Name not given - let's call this one "Frisky Freckles"
41 - Name not given - I'll call it "Too-Creamy Coffee"
42 - Laknes
No image of a freshly abraded rock has been uploaded to the JPL server as yet, and we've only received 10 frames of the abrasion operation so far (spanning about 10 minutes of work), so I'm not sure what to think. Did the rover sense a problem and end the abrasion early? As the animation shows, the arm and the abrasion bit actually shifted a bit during the operation, which is not unprecedented, but it may be that Percy stopped as a precaution.
All the other recent abrasions took longer than 10 minutes (between 15-25), so I can imagine that the process wouldn't quite be done. ~~An earlier post by Paul Hammond shows that Percy is currently very close to the site of abrasion patch #40, which was evidently easier to work with than this weak, fractured stuff, though it was only metres away from here.~~
The rocks on this great big crater rim are yielding amazing science, but they are damned finicky to work with.
EDIT: As of this sol (1544), Percy is about ~100 m east of the site of abrasion patch #40, and ~100 m west of abrasion patch #38. My apologies for the error!
Two images of the Nili Plateau landscape to the west of the rover: one taken at about 1:30 PM local time, the other at about 7 PM, in early summer.
The evening shadows really give the landscape a definition and intrigue which the hazy afternoon sun barely hints at, with even small pebbles standing out, and those sandy mega-ripples down below much more easily identified in the distance.
OTOH, I find that the rover tracks (on the right) become harder to see in the evening, so your hiking skills and common sense are key on late-day excursions. You definitely don't want to be lost in this landscape after dark as temperatures quickly head for -100 ºC...
Original NavCam image from Sol 1519, taken just a few hours ago
Some quick analysis:
Well, let's see... this one isn't fractured like half the patches we've made on this outer rim of Jezero (e.g. #39, #36), has a neat circular outline, and seems to have reached a decent depth. Seems like a clean abrasion to me. So that means it would be difficult to sample, right? 😆
The target rock seems to have been chosen in part because it forms small resistant "nubs" (that is, it forms little ridges; the stuff hasn't been eroded down to near-perfect smoothness, like some other outcrops that gave the sampling system a lot of trouble). The chisel marks on this patch - the lines radiating from the center - aren't very distinct like past ones (e.g. #30, which features some harder volcanic minerals), so it is probably average in terms of hardness.
Just look at all those dark spots, dramatically sprinkled through the dark tan body of this rock! Patch #39 had dark grains too, but they were much smaller, much more rounded; the science team thinks those are spherules embedded in the rock up there. Not so down here. If you zoom in, you can see that the dark material seems to be made of clumps of different, smaller grains, rather than just being one kind of mineral. It looks like we've got a grab bag of different things going on here, which is always exciting! In fact, this one doesn't really resemble any of the prior 39 patches. And that only makes this one more interesting, because...
Percy is near the bottom of the outer rim, just above the local floor of the Nili Plateau, which features some of the oldest known rocks on Mars - and could be dramatically different from what Percy or any other rover has explored so far. Yes, we know Mars was wet, we know there was a much different climate billions of years ago - but when did that begin? We just might be in the right place to begin finding out...
For those unaware, Perseverance and Curiosity are both armed, like the good patriotic American rovers they are - equipped with lasers which have a definite scientific function, but which also (let's be honest) serve to dissuade any Martian critters they come across from getting too close...
Let's hope Sheriff Percy doesn't need to use it.
Original image with caption (MastCam, sol 1495)
They haven't sealed sample #29/Bell Island, no.
Was I correct in understanding they're going to seal tubes only when they know they've got something sufficiently compelling? Until they've mapped the broad outlines of the rim and adjacent Nili Planum, I'm sure they won't be sealing anything. At this point, with the hints they've disclosed recently, I'm not sure we properly understand the mineralogy of these lowest layers... well, I don't, certainly.