Thanks for posting these. Do you prefer this JPL version of the overhead view to the contour-lined ESA one?

You mean you didn't manage to get all your wheels dragged through slippery mud, or get sand sliding up and down your back for months at a time?

...

No wonder Percy hasn't proven the case for biology yet. It's too damned organic and sexy as it is. No witness tube can help the rover escape its own hot signal. That bot is living its best life!

You mean "notional path to the SSW", Paul, no?

STOP STOP I'M GETTING A NOSEBLEED

(OK, I know Opportunity was a lot higher up in elevation. But that's not a fair comparison - "Oppy" was born lucky and everybody knows it. The wind was always at that rover's back and it never had to land in a 1500 km-wide hole punched out of the highlands...)

Don't be all proud of yourself. The rover drivers will be given control of the death ray (sorry, the "breakdown laser spectrometer") when they summit the rim as a reward for their hard work. They'll be carving out the words, "We Persevered, ******s" into the finest basement rock any rover has ever tasted.

Beat that.

Oy. Less than 5 vertical m cleared after a whole week of short slippy drives. I'm not sure what I was expecting to find on this rim, but this terrain wasn't it.

EDITED TO ADD: I meant - only 5 m on this drive, after a whole week of slippy drives, with less than 10 vertical m cleared on any one drive. And this is hardly the softest-looking crater rim we've seen on Mars...

While I'm being chatty, I'd like to ask you if you have any suggestions re: contributions to this community or instance or whatever we call it. I often see things in the raw images that I feel like pointing out here. In reading social media since this mission started, though, I see vast knowledge gaps in people's understanding of basic geology (or "earth sciences", if we can use that term for Mars - maybe "environmental sciences" is a better term), and I sometimes feel I should try to shine a light in those gaps. I've thought about breaking down some of the big science papers/results from this mission here, but I wanted to ask you about this first, as I think you have a better feel than I for what people might be interested in actually reading.

You're talking sense, Paul. As you say, opinions certainly differ, especially among people of different scientific disciplines (e.g. meterology vs. geology), and that even extends to the mission PIs. Steve Squyres was certainly driven and focused in achieving his science goals, which meant that the MER missions drove hard as well. John Grotzinger was criticized for not connecting the dots and "lacking focus" on a big flagship rover. From everything I've seen and heard, Ken Farley is being more careful in balancing priorities (and I'd say his job is a lot harder here, considering the needs of sample return!) All that being said, even pure geologists will certainly disagree amongst themselves, though we don't see that here as interested members of the public.

I'm not privy to the inner workings on this project by any means - certainly not directly. Having observed prior missions from a somewhat closer perspective, however, I see Mars 2020 as very, very driven by the work of other missions and a surprisingly broad community. Orbital spectroscopy and geologic mapping has guided this rover in detail from the very start, to a degree greater than I remember even for MSL, and I'm not aware of much debate about the rover's planned route at any point since before landing. I was personally quite surprised by the short amount of time that Percy spent in Neretva Vallis (amazing place!), to say nothing of acquiring only one sample. Yes, there aren't many spots as interesting as Bright Angel along the traverse path, but I still don't agree that one sample was enough, and I somehow doubt that I'm alone in that opinion.

I've seen dust storms before - the largest ones, the global ones, even through backyard telescopes. If you're working right on the surface, they're not fun.

I'm not often surprised anymore by whitish or light-toned materials near a rover since Spirit uncovered all that whitish silica with its dragging dead front wheel, all those years ago. It seems we often find that Mars is red only until you literally scratch the surface.

I have to say that Percy often drives right past plenty of rocks I'd like to investigate more. I know that Ken Farley et al. are doing just that with remote sensing (the results of which we aren't privy to for quite a while), so they have some idea of what they're looking at, but I'm often tantalized by a lot of this stuff.

For God's sake, stop it with the conspiracy theories. Trace Gas Orbiter would absolutely not miss the, well, methane emission, from a single baby cow, let alone an adult specimen worthy of being prepared as wagyu. Everyone knows that a Japanese master chef would quit (or worse...) before disgracing himself thus. He would never abandon a thickly-marbled specimen on a great big windy crater rim like this.

This is Mars. If you want your vulgar gyudon, there's plenty of that on the mad blue planet next door. Martian wagyu should be part of the finest sukiyaki, to be eaten in formal dress, in deeply contemplative silence.

... I should add - if you can get a sample of this rock for us, we'll even let you eat part of it. It might be a bit salty, but you can be pretty sure Martian beef is nitrate-free...

The idea that this "zebra" or "bad camo" rock could be metamorphic is really something, an interpretation I didn't even seriously consider. If this is metamorphic, one would think at first glance that it isn't more of the same material we've sorta-detected on Mars already, which is probably the hydrothermal or shock metamorphic kind. Mars Guy considered metamorphic rock in his last video only to discard it...

Then again, the Nili plateau region just beyond the crater rim is supposed to be so damned old, even for Mars, that it could preserve evidence for all kinds of craziness, and I'm not sure we can rule out that this rock isn't impact ejecta from the plateau. Maybe this thing doesn't preserve evidence for something as Earth-like as plate tectonics, but that banding pattern needs a deeper look. It may not be a match for the neatly-striped metamorphic rock of Earth, but Martian metamorphism that may have occurred deep within the crust is something we shouldn't ignore. At the very least, I'd like Mars Guy's comparison of this rock to freaking dolomite to be put to the test. There's more evidence for plate tectonics on Mars than there is for that stuff!😅

I'm assuming this is one of the larger climbs/vertical displacements that Percy has managed in a single sol. This old crater rim is definitely the steepest terrain the rover has tackled, which might limit the rover's progress on driving days, but I wonder if the all bedrock we've encountered along the way is enticing the scientists enough to take it slower.

How like you people to constantly reference your tired, dirty terrestrial examples, your lousy "Earth analogues". Anyone that's been paying attention knows that Martians craft things like the ultimate artisans they are, applying the most gentle and skillful touch, tentacles perfectly co-ordinated. Humans go on and on about the "Inca City" and the "Face on Mars", but Martians work every crevice of every worthy rock.

If Earth had a real space program, or just real science, you'd see them dancing on every dust mote, and you might even catch them making lewd gestures when Perseverance fries yet another rock to "analyze" it, but you're too intent on your carbonates and silicates and phosphates...

Nuclear-powered. Ridiculous.

I mean, if you're going to engage in clickbait, you may as well get the best return on your deception possible.

Picture it: a dark future where MSR's 2nd-gen twin helicopters fly toward the grizzled Perseverance, many years from now. While one drone is recording, NASA can execute commands aboard the rover and the 2nd drone to create the ultimate sci-fi action scene: Percy firing its "LIBS" (i.e. Star Wars-style laser) at the approaching drone.

If Steve Ruff does the mock-up of this for his channel, I'm sure we could convince NASA to do it. Hollywood will pay big for the rights to this Martian Robo-Wars scene, when people realize that AI-created slop is less exciting than actual footage.

And all the low-lying terrain in this image was under water...

I am fascinated by Mars as it is. Even so, this amazing image really forces me to stop, and stare, and imagine this scene, imagine Mars, as it was. It's artfully framed, yes, but I'm still stunned to visualize how those old, low, rounded-down ridges in the background would look entirely different if they were encompassing open water. Every time you think you're starting to understand Mars...

Very late reply, Paul, hope you don't mind:

I'd love to contribute here a lot more - I've been planning to do so for a while now - but I tend to write very long-winded posts (see above, again) which maybe doesn't work on social media, and I'm also not one-tenth the geologist Steve Ruff is. If you think my somewhat inexpert posts are OK, though, I'm happy to oblige when I actually manage to find the time.

Wouldn’t we expect all the ground water to have no dissolved oxygen?

Very late reply - but your question is totally fair, so I hope you don't mind:

On the face of it, you'd expect Martian groundwater to be pretty damned poor in dissolved oxygen, yes, and groundwater on Earth does get its oxygen almost entirely from the atmosphere, as you mentioned. (This would be easier on Earth than Mars due to the greater atmospheric pressure, among other things.) However:

If you've heard anything about recent discoveries of "dark oxygen" being generated on Earth's deep seafloor, you might agree with me that nature often finds a way to create chemical niches where interesting stuff happens. In the just-discovered terrestrial case, metals on the seafloor are essentially acting as batteries, zapping water and splitting the oxygen off from the hydrogen. Obviously I can't expect that this process was occurring at the Jezero Delta, but I'm cautious about saying that the groundwater there never had any dissolved oxygen, especially when we know that hot water can break down minerals and release the oxygen within.

So again, the question is a good one, but it's already been partially answered by Curiosity, which found the following on the floor of Gale Crater:

Trace amounts of the element manganese typically exist in basalt. To get a rock with as much manganese as Caribou has, the manganese needs to be concentrated somehow. The rock has to be dissolved in liquid water that also has oxygen dissolved in it.

If conditions are right, the manganese liberated from the rock can then precipitate as manganese oxide minerals. On Earth, dissolved oxygen in groundwater comes from our atmosphere. We’ve known for some time now that Mars once had vast oceans, lakes and streams. If we could peer onto Mars millions of years ago, we’d see a very wet world. Yet we didn’t think Mars ever had enough oxygen to concentrate manganese—and that’s why we thought the data from Caribou must have been an error.

In the Earth’s geological record, the appearance of high concentrations of manganese marks a major shift in our atmosphere’s composition, from relatively low oxygen abundances to the oxygen-rich atmosphere we see today. The presence of the same types of materials on Mars suggests that something similar happened there. If that’s the case, what formed that oxygen-rich environment?

Good article to read if you have the time...

I'm already committing the cardinal sin of discussing redox states on social media, Paul, so forgive me for adding this note:

With all the groundwater that seemingly flowed within the rocks of this region, oxygen needn't have been present at the time of deposition. Alteration/diagenesis seems to be pretty damned important here. (Further aside - non-geologists are always shocked to learn that oxygen is part of so many minerals and rocks to begin with. Maybe it's easier to talk about free oxygen, the kind that isn't already attached to the iron or magnesium of whatever...)

Not necessarily. Here comes another episode of Wide World of Iron Minerals...

The mineral that Prof. Ruff refers to - hematite - contains ferric iron, as opposed to the other kind, ferrous iron. The difference between the two is simple - ferric iron is missing 3 electrons, whereas ferrous is only missing 2. Some process has to strip the ferrous iron of that extra electron - it requires noticeably more energy to make ferric than ferrous. Mars has plenty of the ferrous kind, like you find in the rocks on the Jezero crater floor; it's what you'd generally expect to find in the planet's hard rock. So you want to pay attention when you get the ferric kind - especially when you find it in the "soft rock", like Percy is exploring now. One way of making ferric is exposing it to free atmospheric oxygen and moisture, as on modern Earth, producing various "oxidized" minerals, which some casually call "rust". But there are other ways for oxygen to do the job, as well - say, when it's dissolved in groundwater. And this Neretva Vallis site evidently had plenty of groundwater. The oxygen content of that groundwater, however, is kind of a big question.

Thing of it is, hematite can also be produced without water and oxygen, purely by volcanic action, too. So hematite has a lot to say either way, it's one of those minerals to watch.

The phenomenon of iron minerals on Mars has been a big deal, and will continue to be. Opportunity's landing site was chosen because the variety of hematite that satellites detected there was unusual, and that led to the discovery of sandstone laid down by massive amounts of water - the first sedimentary rock ever discovered off Earth. Without that discovery, I'm not sure that Percy gets sent to Mars. And I haven't even started to talk about other sources of ferric iron, like you find in the dust, or all the weird stuff that happens when sulfur and iron get together and have a baby...

EDITED to talk about hard and soft rocks. Don't giggle, we're geologists.