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.

The thermal cycling hypothesis for erosion has been advanced for Mars since the 1960s - before we had landed even a single mission on the surface - but personally, I’m not convinced. The effect should be ubiquitous and would apply to every clast/rock a rover can see, but just about any landscape shot shows that there are plenty of rocks without the network of cracks you’d expect. Paul Hammond is correct in pointing out that rocks preferentially fracture along planes of weakness (the direction/face where a mineral is naturally weakest), and the composition of the rocks should have a lot to do with it, but I still think that the process would be a lot further along after billions of years.

The potholes you see (…feel) in places with sub-zero winters show us exactly how good freezing/thawing water is at breaking and flaking hard surfaces, so Mars Guy isn’t wrong to point that out first in the video.