SpecialSetOfSieves

Awesome mosaic, I love it when the rover gets up to this rougher steeper kind of ground.

BTW, the drive was to the east 😉

Despite their superficial similarity to Opportunity’s “blueberries”, the spherules at “Rowsell Hill” have a very different composition and likely origin. In Meridiani Planum, the spherules were composed of the mineral hematite and were interpreted to have formed in groundwater-saturated sediments in Mars’ distant past. By comparison, the spherules in “Rowsell Hill” have a basaltic composition and likely formed during a meteoroid impact or volcanic eruption. When a meteoroid crashes into the surface of Mars, it can melt rock and send molten droplets spraying into the air. Those droplets can then rapidly cool, solidifying into spherules that rain down on the surrounding area. Alternatively, the spherules may have formed from molten lava during a volcanic eruption.

Impacts and eruptions... both violent events. Neither exactly what Percy was sent to look for, you'd think - namely evidence of water action, and possibly traces of biology.

Except that there's a very important difference between the two: impacts are common everywhere, from Mercury to Pluto, and provide no proof that a planet has a geologic "pulse", that its insides are warm and active. Whereas volcanic eruptions prove exactly that. If we had these spherules in hand, we could determine their age and know that this part of Mars was still active at that date. Put that information about Mars' internal heat together with the dates of the old lake sediment we sampled inside Jezero Crater, and you've got yourself a story.

You don't get this sort of information by landing in the middle of the plains, as the Chinese sample return mission and the SpaceX proposal would have it. Just saying.

40 m elevation gain with the rover parked at a 15º pitch angle... judging by this rear hazcam image, there was some rougher driving there, at least toward the end. The rover's current location seems like a fairly significant detour from the route identified a few months ago, and there's a big patch of bedrock about 20 m uphill along its current heading.

I wonder if they've identified something interesting further upslope. This ground we're on is kind of rubbly, and I don't think we needed to come up this high if we were simply skirting that sand trap in the flats to the south. Perhaps that bedrock further up exposes material from a stratum we didn't sample back on Witch Hazel Hill? I have no objection to taking a look, but maybe you should pay me no mind... I'm the last person Ken Farley listens to when it comes to driving this rover 😞

Do we have a name for this rock?

Paul Hammond gave a comprehensive reply to this already, but to my eyes it strongly resembles an orbital view of Iceland 😀

Is this method more merciful and humane than using the laser? No doubt the pundits and the downvoters will be along to tell me soon enough.

The abrasion was partly successful:

Interesting texture. Are those grey splotches at the top and left of the patch part of the greyish coating or crust that we saw before we abraded, or are they (very) large unweathered grains in the rock's interior?

They've got quite a few similar targets nearby if they don't want to put the instruments down on this patch for a closer look...

Thanks, Paul! I've updated the post, using the animation you've provided.

😃 I hope some rover drivers get to see this question - it's a very good one, just funny if you've seen the whole mission.

In the past - before Curiosity landed - NASA definitely chose rover landing sites based in part on their (presumed) smoothness and traversability (e.g. Opportunity). This was also true for the first Chinese lander.

In the case of Perseverance, the "rockiness" in this region actually varies quite a bit over fairly short distances. The terrain we've been exploring since late 2024 was chosen for two reasons: ease of traversal (when we were climbing out of the Jezero Crater) and science (our current location, Witch Hazel Hill). When we were down on the old river delta last year, though, the rover drivers had a very difficult time with terrain like this and this.

Witch Hazel Hill is smooth in part because the bedrock here is soft and easily eroded. Quite a bit of it has significant clay content, like you'd find in Earth soils, due to heavy interaction with water in the geologic past. Down on the crater floor where we landed, where the terrain is made of volcanic rocks, there are scenes like this. In the end, the rover drivers are pretty protective of their vehicle, so we tend to prefer smooth stretches for driving.

Points of interest:

• White splotches - alteration minerals? (Sulfates?). Clustered in top centre of image.
• Dark grey brown material: dominant material here. Doesn't appear to be the famous purple coating material. Friable (crumbly), based on the HazCam images, but seems to be more resistant/better represented than the rest of the stuff in this rock. Features fine cracks/fractures/joints. Most of it is dull, but some appears to have a bit of lustre (shiny) - see upper right.
• Light grey zones: They feature "spots" - embedded tan regions, and smaller darker regions. Some of it is covered by white splotches, but some zones have none whatsoever. See top centre for some clear examples.
• Isolated tan zones: Smaller than the light grey zones, and almost entirely free of white splotches. Clustered nicely at right centre.
• Small dark elongated clasts, light brown and black.
• Small patches of purplish material: the usual coating material? Very little of it here. See lower left.

Now in a place like this, you always have to consider an impact origin: we're on the edge of a fair-sized impact crater and we've found plenty of material that was heavily modified/created by one or more serious impacts, including three of the four samples we've actually managed to bag on the rim. Impact breccia is complex stuff, a salad of ejected material that gets fused together and then solidifies into a chaotic and beautiful mass.

In this case, however, I really have to wonder. If this is impact breccia - even a breccia altered by long-lasting groundwater - I haven't seen a texture like it. The light grey zones and tan zones have fairly round outlines, rather than angular ones, which you would expect from shards of broken and ejected material. The distribution of the different zones (tan and grey zones tend to be grouped in small areas) doesn't seem random.

All in all, for me this is one of the most fascinating images of the entire mission, and that's saying something.

They've even taken a night-time shot of this stuff, which... yeah, I really wish we could sample here. But the LED-lit shot is seriously full of detail:

Hahaha Beat me to it, Paul Hammond. 😄

I am reminded of this Mars Guy episode from last year, but there are significant differences here, even before you consider the difference in the two settings (river valley vs. crater rim). They're not going to abrade here - not this target specifically, anyway - but I see more than enough to investigate at this site for a few sols. And yet this friable, fractured material we're targeting is small enough to be hidden by the sandy ripples...

This mission. I have to pinch myself.

I think we have a natural ally for MSR here, Paul 😁