SpecialSetOfSieves

😃 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 😁

the Curiosity science team is after all the details at this time to assess whether water indeed was responsible for the more resistant nature of the ridges. Spotting one that is so clearly raised prominently above the landscape — and in easy reach of the rover, both from the distance but also from the path that leads up to it — was therefore very exciting.

That was just a nice little reminder: for everything we're seeing up on this mountain, and learning about this planet, we're still limited in what we can really investigate. And we are therefore biased in what we can discover right now. I really wonder how our view of this environment is being skewed by that. Even Earth geologists have this problem: so many of the rocks we want to sample are far underground, under the ocean, or only just barely exposed.

On Mars, though? So many things that the rover sees are still just out of reach, even with the lasers and telephoto lenses and other remote sensing instruments we're packing. I wouldn't trade this mission for anything, but we're still not that far past the "scratching the surface" phase.

Politics reply:

What good did the moon landing do for the average man?

Directly, immediately? In the 1960s? Aside from the people employed working directly or indirectly on space efforts? Almost none. Is that really the answer you're looking for, though? Scientific knowledge can take decades or even centuries before it improves our lives tangibly. But I think you know that, so I won't argue with you about it.

Concerning the waste of time, money and attention - LOL there was the Vietnam war, too. I'd argue was less beneficial to humanity than Apollo. I am only raising this point because I think it's unfair to place blame for lack of social progress at the feet of scientists, or a sub-set of scientists. We're collectively responsible.

Otherwise, I generally agree with you. The Apollo program was not conceived or executed to benefit science. But Apollo did mobilize science irrevocably. "Planetary science" as a discipline, community and way of thinking didn't exist before Apollo. Very few people, even in the science community, were comparing planets and learning something from that before about 1970. Ditto for environmental science - and that community, too, barely existed before Apollo. Even though that field got a headstart due to people like Rachel Carson.

Would you have improved social conditions for anyone by cancelling Apollo/Gemini in, say, 1964? I'm not so sure about that. 1968 certainly implies otherwise. I'm here to tell you that exploring neighboring worlds is a social good because you learn the parameters of your own environment, parameters you MUST keep an eye on to keep Earth habitable. But that social good is a joke if people can't walk down the street without worrying about ICE raids. So yeah, you're right, racial hatred obviates this beautiful and essential realization that we're connected to a bigger universe. Would you have the scientists of the world hide their knowledge away because we live surrounded by ugliness? All I can say to you is that we live here too, and this fight is ours as much as yours.

Science reply:

We learned the origin of the earth and moon and NASA invented a few good gadgets ... But I don’t see how those outweigh the cons of the Apollo program.

It's a lot broader and more subtle than just the origin of the Earth and Moon. Apollo rewrote your geology textbook. Not the lunar geology text - the one for Earth. And not just the chapter about origins. This tends to get obscured because there was another revolution going on in Earth science at the very same time - a little thing called plate tectonics.

Direct results from Apollo, corroborated by old Soviet and modern Chinese automated landers:

• Planets are born hot, and their insides stay hot, for a very long time
• The threat from impacts (asteroids/comets) is real, pervasive and ongoing
• Planets don't stop evolving (their surfaces change, sometimes dramatically, and rather suddenly in geologic terms) for a very long time after they're born

Indirect result from Apollo:

• Earth is part of a larger natural system that affects it every single day - larger even than the solar system; let's call it the local Galactic environment

Of the three direct results, two sound obvious. Naturally Earth is hot inside; where does lava come from? Of course space rocks can bang into us; what would stop them? None of this, however, was evident certain to a huge number of geologists, physicists, or chemists in the 1960s (or '70s, or even '80s... some people never change their minds. They just die). And when most workers in a given field are against you, progress tends to be rather slow. Walter and Luis Alvarez had a hell of a time convincing people that an asteroid strike could have ended the Cretaceous, not to mention the dinosaurs - I mean, there isn't even a crater in the Yucatan, it's flat down there! (LOL That debate still isn't over, even today...)

As far as I can see, direct result #3 (about planetary evolution) hasn't entered the zeitgeist yet. Yes, people are (wisely) alerted to climate change, but that's just a little tweak compared to the immense environmental changes that we know took place on Venus, Mars and Earth - and I'm just talking about the ones that have occurred since complex life emerged here, not the ones from billions of years ago.

And that indirect result? I still know a number of scientists who hem and haw and won't quite agree that Earth's environment doesn't suddenly end 100 km up. The Voyager probes show us how bad the radiation is when you get far enough away from the Sun, and I don't know if you even do Voyager without Apollo. But Apollo, uniquely, shows you something else - the Sun hasn't always protected us from that bigger dose of cosmic radiation that the Voyagers see. Sometimes that heliospheric shield shrinks, and the planets get a lot more radiation than we do today. And that's just one of the synergistic results, there are more.

IMO the primary lesson we learn from geology is that environments change in time. Please note my use of the PRESENT TENSE in this reply, because none of what I am discussing is forever confined to a remote past - all of the planetary evolution processes I'm talking about can still occur today, and are certain to recur in the future. Geology left the silo to become a much more interconnected science partly because of Apollo - and the thing is, it became a science about THE FUTURE as well as the past.

Apologies for the overly long reply. Apologies to my science people for oversimplifying here.

In the USA we wasted time, money, and media resources going to the moon while black people were treated as less than citizens and millions were living in abject poverty. Not much has changed on that front for the countries entire history. What good did the moon landing do for the average man?

I'm sincerely wondering if you'd like an answer to your question. I can provide you the science perspective, if you like, not to mention a political one. Not interested in an emotional debate here, you're entitled to your point of view and your polemic, if that's all you prefer.

And destroyers.

Just a few months into its reign, the US regime intends to ruin decades of progress in science and space exploration:

On May 30, 2025, the White House Office of Management and Budget announced a plan to cancel no less than 41 space missions — including spacecraft already paid for, launched, and making discoveries — as part of a devastating 47% cut to the agency’s science program. If enacted, this plan would decimate NASA. It would fire a third of the agency’s staff, waste billions of taxpayer dollars, and turn off spacecraft that have been journeying through the Solar System for decades.

Shutting down a working, completely functional mission like New Horizons, in particular, that may just be on the cusp of a huge discovery - it has seen signs of a new, second "ring" to the Kuiper Belt - is the ultimate repudiation of the American self-image as explorers of the frontier. And all of this at a time when the Chinese are just about catching up to "the West" in space science prowess.

As a kid, I never understood what the Romans were trying to say with their Janus myth. Turns out that Orange Janus is simply the god of endings.

On these quiet sols, with minimal driving, have you ever suspected that the rover drivers secretly want to execute moves like this? The topography is maybe not a perfect match, of course, but with gravity reduced by 62%, I'm sure Percy could catch some air.

With Ingenuity grounded, there'd be no one to witness these moves, of course, but I'm absolutely certain the science team would eventually catch on when they see that the rover deck has inexplicably been shaken free of that loose sand cover one fine morning...

Would this... proposed legislation... mean that SpaceX will now be prohibited from flooding LEO with Starlink comsats?

Loading the upper atmosphere with ozone-destroying aluminum and other heavy metals as those things fall out of orbit, not to mention rapidly increasing light and RF pollution, definitely qualify as an uncontrolled geoengineering experiment, albeit one whose effects were known before launch. I could go on about the deleterious effects of these orbiting swarms, but - the ball's in your court, Congresswoman Greene.