Planetary Radio: Space Exploration, Astronomy and Science - Simulating Psyche: Modeling craters on a metallic world

Episode Date: October 25, 2023

NASA's Psyche mission launched on Oct. 13, 2023 on a journey to explore its namesake, the metallic asteroid Psyche. Simone Marchi, co-investigator for the Psyche mission, joins Planetary Radio to share the creative ways their mission team is working to understand cratering on metallic worlds, including everything from computer modeling to blasting metallic meteorites with projectiles. The Planetary Society's Public Education Specialist Kate Howells will discuss the Japanese Space Agency's newest moon mission, SLIM. Then, Bruce Betts, the chief scientist of The Planetary Society, will share his experiences with crater modeling and a fresh random space fact. Discover more at: https://www.planetary.org/planetary-radio/2023-craters-on-psyche See omnystudio.com/listener for privacy information.

You think asteroid Psyche is totally metal? Wait until you hear how the mission team models its craters, this week on Planetary Radio. I'm Sarah Al-Ahmed of the Planetary Society, with more of the human adventure across our solar system and beyond. NASA's Psyche mission to explore a metallic asteroid has finally launched, and it's headed to its asteroid namesake. Simone Marquis, co-investigator for the Psyche mission, joins us this week to share the creative ways that their team are learning more about cratering on metallic asteroids. And by creative, I mean they're straight up blasting things at meteorites. It's amazing. It's amazing.

Kate Howles, the Planetary Society's public education specialist and Canadian space advisor, will also pop in to tell us more about the Japanese space agency's newest moon mission, SLIM. Then, our friend Bruce Betts, the chief scientist of the Planetary Society, will share his experiences with crater modeling and a fresh new random space fact. If you love Planetary Radio and want to stay informed about the latest space discoveries, make sure you hit that subscribe button on your favorite podcasting platform. By subscribing, you'll never miss an episode filled with new and awe-inspiring ways to know the cosmos and our place within it. There's been so much awesome space news recently that you may have missed the launch of SLIM,

the Japanese Aerospace Exploration Agency's, or JAXA's, newest moon mission. On September 6, 2023, SLIM blasted into space aboard an H-2A rocket from Tanegashima Spaceport in Japan. A huge congratulations to the team from everyone here at the Planetary Society. Kate Howells, our Public Education Specialist and Canadian Space Advisor, is here with the details. I love seeing you and everyone in the office, but, you know, it's extra special to see you. You live in Canada, so thanks for coming all the way out here. Oh, it's my pleasure.

It's great to be able to be in person with everyone and be in the office, which is the coolest place in the world. It really is. I bet if we just recorded this week and let everyone, like, see all of our adventures and how cool everyone is here, it would be. If you could somehow do an audio tour of the office and all of the cool space stuff that's in here, it would be so good. Oh, that's an idea for a future show. But we're here to talk about the Japanese Space Agency's SLIM mission. You didn't write this article. One of our freelancers, Andrew Jones, wrote it.

He's always a fantastic writer about space agencies that we frequently don't hear enough about. So what aka JAXA, and it launched in September. It's on its way to the moon. It's going to get into a particular orbit as spacecraft do. They take these long journeys to get to just the right place. It's going to try to land on the moon in early 2024. And what's special about SLIM, well, there's a few things. The main goal of the mission is to demonstrate a very precise landing. So most of the time when something aims to land on the moon, it sets a target ellipse, so a sort of elliptical shape area that it's trying to land in. That's usually a few kilometers in length or a few miles for American or UK listeners. For the SLIM mission, it's trying to land within a target area of 100 meters or 330 feet.

So this is a much smaller, it's really like a precise target that they're trying to hit. So if they are able to do this, it will advance lunar landing technology. It'll also make Japan the fifth country to land on the moon. India just recently became the fourth. And so it would be an expansion in the number of countries that are able to achieve lunar landing. I mean, that's a really useful technology because so frequently we see these situations where it's like, OK, we have this landing ellipse, but what if there's a rock? What if we accidentally end up in a crater? You know, and especially on the moon, I imagine trying to get out of those craters if you're a

little rover is almost impossible. Yes, certainly. So being very precise is very helpful. Also, one of the reasons they want to develop this precision is that as we advance lunar exploration, settlements on the moon, that kind of thing, you're going to need to make sure that you can be very precise in your landing. You know, if we have lunar settlements built, you don't want to accidentally land on one of them if you're trying to land nearby. So the other thing too that they point out is that as lunar science advances, we're going to want to be precise in where we land scientific spacecraft, because if you want to investigate something in particular, and you don't have rover technology, you just have a lander, you want to make sure you land

it in the area of scientific interest. So this technology, if it works, could advance exploration and science. Super cool. And I understand too, that there are some really weird rovers and things that this mission is going to be deploying. Yes. So SLIM carries with it two small rovers and things that this mission is going to be deploying. Yes. So Slim carries with it two small rovers that are very unconventional in the way that they go about roving. One of them called Lunar Excursion Vehicle 1, very creative name, uses a hopping mechanism to get around. And the other one, Lunar Excursion Vehicle 2, uses a sort of rolling mechanism. It's about the size and shape of a baseball. So it's a spherical rover. And it moves around by separating its two halves and sort of crawling in a rolling manner by swinging from side to side to propel itself forward. So it's

just a very cool, new way of moving about on another planetary body. And I really hope it works and we get to even see some kind of animation of how it might look. But these rovers also carry cameras on them. So we might even get to see some firsthand imagery from the rovers. Whether or not they work, that imagery is going to be awesome. Yes, agreed. It just makes me so happy that so many more nations are going to the moon. It's really an international effort these days. And it feels like this Artemis Accords coalition is really taking shape. Yeah, absolutely. The future of human spaceflight on the moon and also just lunar investigation is very much a global effort. We're seeing this

so much more compared to during the Apollo era. And there's actually a really great infographic in the September issue of the Planetary Report, our quarterly member magazine, but that's also available online for free to everybody. There's an infographic that compares the Apollo program with the Artemis program, looking at things like how many countries were involved, whether commercial partners were involved, and you can see how much more international and just generally collaborative the Artemis program is. And I'll put a link to that on this episode of Planetary Radio, along with a link to this article so that you can read more about JAXA's new ideas for how to land on the moon.

Well, thanks for joining me, Kate. Thank you, Sarah. to land on the moon. Well, thanks for joining me, Kate. Thank you, Sarah. Speaking of recent amazing space launches, NASA's Psyche mission launched on October 13, 2023. It went to space aboard a SpaceX Falcon Heavy rocket from Launch Pad 39A at NASA's Kennedy Space Center in Florida, USA. I've been so looking forward to this mission's launch. I could tell you all about it, but let's hear it from Lindy Elkins-Tanton, the principal investigator for the Psyche mission. Here's what she told me during our first conversation on Planetaria Radio in March

2023. The Psyche mission is named after the asteroid Psyche, which orbits out in the main belt between Mars and Jupiter. And why would we want to go to this asteroid among the, what's the estimate between one and 2 million asteroids in the main belt, I think. So here's this one particular one. It's because it seems to have a metal surface. And we as humans, we visited bodies made of rock like the earth and bodies made of gas and ice like Jupiter and Neptune and icy moons. But we have never visited a metallic body. And there are only a few in our solar system.

We think maybe nine of the asteroids are made of metal. And this is the biggest one. So I kind of feel like it's the space equivalent of discovering Antarctica. Like it's a new kind of place that humans have never been. And frankly, it is a big mystery, which is what makes it exciting to me. We'll be hearing from Lindy again in our next show. I can't wait to learn about her experience during launch day. Can you imagine working on a space mission for years and then finally,

after all of that time and effort, getting to watch it soar into the sky? It gives me chills just thinking about it. One of the reasons I'm so excited for the Psyche mission to reach its target is because I want to know what craters look like on a metallic asteroid. That has to be completely mind-blowing. Our guest this week is an expert on the subject. Simone Marquis is a staff scientist at the Southwest Research Institute in Boulder, Colorado, USA. He's co-investigator for Psyche, but that's just one of the many missions he's worked on. He's also deputy project investigator for the Lucy mission, which will investigate Jupiter's Trojan asteroids.

Simone is deeply involved in understanding the bombardment history of our solar system through the cratered terrains of terrestrial planets and asteroids. Let's learn more. Hi, Simone. Hi, Sarah. Thanks for joining me and congratulations on the successful launch of the Psyche mission. Oh, thank you. And my pleasure being here. It's got to be really exciting working so long on something and to finally see it go up. Did you get a chance to be at the launch? Yes, indeed. Yes. Both things you said are important. First thing, we've been working on this mission for a long time already, and it was very nice to see liftoff and go to space. And I was also able to be there in person, which was also very exciting because any launch of a mission is always a very exciting moment, particularly so if you are involved directly with the mission that's going to fly.

And you've been involved with so many missions. Have you been able to go to other launches that were for missions you've worked on? Yes, I've been involved and still are involved with other missions. So this was not my first launch, but it was my first Falcon Heavy rocket. And so that was an additional element of interest for me. Did you get to see the boosters come back down and land? Oh, yes. In fact, I planned my location to be as close as possible to where the booster was supposed to land. And I was able to see that clearly. And it was just amazing.

The reason I wanted to have you on this show is because we've talked about the Psyche mission before and how exciting this object is. A metallic asteroid is not something that we can study every day. But what I'm particularly curious about is our understanding of cratering on a metallic body. And you're someone who I understand has been deeply involved in trying to understand this process. So how did you fall into this?

How did you end up in a situation where you were trying to figure out how craters form on a metallic asteroid? Yeah, that's a very good question. And, you know, you have the right person here, because I've been obsessed with craters. And I've been studying craters for over 20 years. And I can say that I have studied craters all across the solar system, ranging from planet Mercury, Earth, Mars, Venus, even, although there are not many craters on Venus,

and then all the way to other asteroids. So it's really something that fascinates me. And what we see in a crater is just what's left behind of a very energetic process. The physics of that, it's what interests me. And eventually, we studied that by looking at the craters that we find on the surface. So when we started looking at Psyche mission and Psyche asteroids, and then trying to plan this mission, it becomes obvious that if this is a metallic object, as we think it might be, well, then we are dealing with the situation

that we don't really have seen in the past, right? All the objects we have visited so far are either rocky objects or icy objects. And so we have a good understanding, I would say, of what the crater looked like on a rocky object. But how about metal? Well, we don't really know. We have never seen that before. And so this was sort of exploring completely new avenue for me to think about cratering on this object. And so that was very exciting.

One of the things that fascinates me about this mission. It's got to be one of the things that's most fascinating for me. It's a very strange object, but I'm trying to imagine in my mind what these craters might even look like. And without going there, the only thing we can really do is model or conduct experiments here on Earth. Yes. When we say that this is a metallic asteroid, what kind of materials are we talking

about? Yeah. So here is the thing, right? This is an object that's very far away from us. And we have a very limited understanding of the actual bulk properties of these objects. And so we infer, for instance, using telescopes, big telescopes even, right? On Earth or even space telescopes, such as the Hubble Space Telescope or even the James Webb. And so we have, using those facilities, we can get the sense of what the composition

might be. But the fact of the matter is, is that we do not really know. We have proxies, perhaps. So if we look at meteorites, meteorites are presumably chunks of asteroids that naturally come to us. We don't have to go to space to pick them up. They candidly come to us. And so, there's a class of meteorites, which are called iron meteorites, that are made

of iron and nickel for the most part. And so, these are very dense meteorites. And so potentially those kind of alloys that we find in this, in this meteorites may be present on Psyche or, you know, there could be other components that are added to the mixtures. As a matter of fact, one thing that we know about Psyche is that the overall density of the asteroid, it's somewhat lower than the density of a solid piece of iron meteorite. And so that would imply that Psyche cannot necessarily be an intact large chunk of iron, nickel, metal like those meteorites, but have to contain

some other elements. What those elements are, it's not obvious. It might be just simply voids or they could be silicates, meaning other rocks embedded with it. So that's still to find. We'll figure it out once we get there. But the general idea is that there might be a significant amount of iron, which might be similar to what we see in this iron meteorite. So we're talking about basically iron and nickel alloys. For anyone who's ever had a chance to go to a science museum and hold one of these

metallic meteorites, we had a chunk of it from Meteor Crater in Arizona that I picked up. And despite being, you know, maybe the size of a large grapefruit, that thing was like eight pounds. It was really heavy. So I encourage everyone to go out and try to pick one of these things up because you will be very surprised. Yeah. But be careful, please.

Because the first time I actually took in my hands one of those meteorites, I didn't really appreciate how heavy they were. And so you can easily break your foot if you're not careful enough. It's true. When I previously worked at Griffith Observatory, there's a desk where we keep one of those. And the floor, unfortunately, got very dented for a while there because despite warning people, they'll still drop that thing and just right into the ground. So we're testing these other meteorites to kind of see how they compare. Do we have any spectroscopic data that can give us an understanding of maybe what the surface material is like?

Yes. So as a part of the telescopic observations that we're talking about a moment ago, we certainly also have spectral data. And it is using spectral data that we can try to infer the surface composition. But here is a strange thing about a metallic object, that in fact, if you take a spectral observation in the visible and near infrared wavelengths, which is most easily accessible from ground-based facilities, well, then you end up with something that doesn't necessarily show you a great deal of details. In other words, when you look at a spectrum, you will like to see absorption bands, right? So, if you have an absorption, that means a dip in the spectrum. Well, that tells you what kind of materials you might have.

You know, I have different materials, have different characteristic absorptions. And so, by measuring those, you can figure out what kind of materials you might have. You know, different materials have different characteristic absorptions. And so by measuring those, you can figure out what kind of material you have. Well, the problem is that metal, these type of metals at least, do not really have many absorption bands at all. And so what you're looking at, it's almost a featureless line. And therefore, it's hard to pinpoint what the composition might be. And to make this story even more complicated, there are other completely different class of materials that have similarly featureless spectrum.

So for instance, you can hold in your hand a piece of a carbonaceous chondrite meteorite, which is an assemblage of silicates, there's potentially significant amount of carbon in it and other, it could be metal as well. But now if you take a spectrum of that, it's also kind of featureless. And so all of a sudden we're dealing with this data that it's not conclusive in what the composition might be. And so this implies that we need to keep our minds open because we may see things differently than what we are anticipating.

Every time we've been to an asteroid so far and gotten up close, they've constantly surprised us. For an example, when they went to asteroid Bennu and touched the surface, that thing was so rocky and full of little tiny bits that the spacecraft almost got entirely swallowed up by the asteroid just by contacting it. So I'm sure that Psyche is going to completely surprise us. Yes. So how are we actually attempting to try to model these craters? Are we using computer models primarily?

We have two means for doing that. The first one will be certainly computer models. We can run sophisticated models in which we simulate a collision. And so that could give us a sense of the outcome. Now we can set up the model to be realistic for an iron-nickel alloy. And so that would give us a sense of what might happen in reality for that kind of collisions. But there is another way of approaching this, as you briefly alluded before, that is doing, in fact, experiments in the lab. And that has become an important endeavor, at least for me, to try to understand how craters may look like on a metallic asteroid. So we have been conducting experiments. We use primarily the NASA Ames vertical gun facility, the AVGR facility in California, which has been built to conduct this kind of experiments. to shoot some of these high velocity impactors into a target that might be similar or in a way might represent psychic compositions.

And so we have over the course of the last few years, we have done several such experiments. And so I think we are building a little bit of a better understanding of what we might expect to see how those craters might look like on a metal-rich object. I love that you bring that up because in a previous week, I believe I was talking with Matthew Siegler. We were talking about a completely different subject, but I asked whether or not people have been conducting these experiments where you actually shoot things into metal to see, and he was like, you have to talk to someone who's been doing this because I hear that it's a lot of fun. So have you actually shoot things into metal to see. And he was like, you have to talk to someone who's been doing this

because I hear that it's a lot of fun. So have you actually been going there in person and just conducting these experiments, having a fun day shooting things into sheets of metal? Yes. Well, it's even better than that. How does it get better than that? Yeah, it gets better than that because we're not just using any random scrap metal or piece of metal.

We are actually using iron meteorites. Oh, wow. Yeah, and so a big part of this was to make this as realistic as possible. So iron meteorites come in a wide range of properties. They have different crystal structure, crystal composition, and so there's a great variety of possibilities there. And so the question is now, how do we go about simulating this in the lab? I mean, in principle, yes, we could cast some iron and use that, you know, sort of lab-made samples.

But we were not able to reproduce the complex texture and composition that the real meteorites have. So, in fact, the first set of experiments, just to make sure that I think we were doing something, going in the right direction, were done with lab-made samples. So these were iron-nickel alloy that we cast with the foundry. We got some blocks out of it, and then we did some tests. But then we quickly realized that we really needed to go to the real thing,

meaning the iron meteorites. And so then we started to try to acquire iron meteorites from various localities. And here I mentioned that the Arizona State University was important for this endeavor because they have a great collection of meteorites and they were able to give us some of their samples so that we could conduct the first sets of experiments. And so we actually did this with three different types of meteorites. And the most amazing thing is that when you start using the real meteorites, because they're complex, as I said earlier, you then see that the outcome of the event is very different than if you were to use, say, another piece of scrap metal that you can find. And so that is why we want to do that. And so realizing that has brought up sort you know, sort of going farther down the rabbit

hole and trying to gather more diverse type of iron meteorites and keep doing this. So we have done quite a bit at this point. I was going to ask how you got those meteorites, but I love that you sourced them from ASU. In my imagination, I could just see people going to Antarctica and combing the ice for enough meteorites to get the science done. Well, that would be fun. I have not done that myself.

We have also purchased meteorites from other vendors. Not all of our meteorites come from ASU because, as it happens, you can buy iron meteorites relatively easily. They're a bit expensive, but clearly it's all justified because we really need to see what happened with this kind of experiments in order to be prepared. It's an important component of eventually interpreting what the spacecraft will find. As a general comment, I would like to make that cratering and the formation of crater is perhaps

one of the most fundamental evolutionary processes that we have on asteroids, right? Once they are formed early on, there could be all sorts of things happening, but then they basically freeze for billions of years, right? And then the only thing that can really shake them up are larger scale collisions. And so they're going to be an important part of the story that will unfold as soon as we get to the asteroids.

And so we better be prepared for that. What were the biggest differences between the actual iron meteorite tests and the ones done with just sheet metal? Did it change the shape or how did that work? So we have done several experiments, right? So we are building up our understanding. The first batch was just any regular, you know, metal that we could find. And so we did some experiments and we produced some little craters on them. They were nice and they were really exciting by doing that. Then we turned our attention to the iron meteorites. And the first

several experiments that we did, they looked pretty much the same as the previous one that we did with some scrap metal. And so first conclusion was, well, maybe it doesn't really matter that we use the meteorites maybe we should just keep doing you know not using the meteorites not to waste as a precious material and because in the end the morphology of the crater is kind of similar well we kept doing though a few more experiments with iron meteorites trying to increase the energy of the collision and all of a sudden we realized that there was something unexpected, at least to me, that was happening. Well, that is the way the metal cracks. In fact, all the experiments that

we did with regular terrestrial metal, we didn't see any major cracking forming in our target. In a way, they are very ductile material. And so they adjust and it's not like a rock that will fall apart and you know completely and crack in all directions um the method behaves differently but when we started increasing the energy of some of our iron meteorites target they start to crack in ways that we could not understand in fact as of today that's still a bit of a puzzle for us. And we are planning to do more experiments in understanding how you can destroy a chunk of metal. That's very important for us because now imagine you have a psyche that possibly contains lots of metal. And then all of a sudden you have a massive collision that could have taken place billions of years ago. So now the question is what that type of collision do for this in terms of cracking and breaking the asteroids.

It's perhaps something we should be considering. And so all of this is sort of a new line of investigation, if you will, that we haven't really thought when we started doing this and it's become very, very fascinating and interesting. This is a guess, but is the metal kind of shearing along like crystallization lines? Is there some indication within the structure of the material that like lines up with those cracks when you do these tests? Yes and no.

That's a puzzling thing. Occasionally we find a crack that seems to be aligned with the crystal boundaries. Some of these miturites, as I said earlier, have clear crystal structure. You can clearly see these are big crystals of the most common, at least, are thionite and camasite. These are alloy of iron and nickel in different proportion and different chemical arrangement. And so you see sometimes these large crystals and you would expect naturally, as you suggested, that the crack will follow that boundary line. And sometimes they do, but not all the times. And we don't understand why at some

point the crack decides completely to go off in a direction that apparently has no reason why. There's another aspect of interest here along those lines is that some of these meteorites, in addition to this crystal structure, they also have inclusions, meaning they have bits and pieces of different type of composition. This could be a chunk of graphite, so something that contains lots of carbon. It could be something that contains lots of sulfur. It depends. Every meteorite is different.

And again, you will expect that because these inclusions are a discontinuity in the matrix of the meteorites, you would expect they could have something to do by driving where a crack will form. And yes and no again. Sometimes we see, yes, there is an inclusion here. It's a big crack point in Tobolsk's inclusion. But there are other cases in which cracks go completely in another direction. And it seems they don't care much about the fact that there are inclusions around. And so, you know, it's a puzzle.

We're still investigating this. That's so cool, though. Where are you keeping all of these bits of meteorite that you've shot things into? Is there an archive where you've got them all lined up somewhere? As a matter of fact, currently, they are all in my office. It's just behind my desk. That's amazing. We'll be right back with the rest of my interview with Simone Marquis after this short break. Greetings, Bill Nye here,

CEO of the Planetary Society. Thanks to you, our LightSail program is our greatest shared accomplishment. Our LightSail 2 spacecraft was in space for more than three years, from June 2019 to November 2022, and successfully used sunlight to change its orbit around Earth. Because of your support, our members demonstrated that highly maneuverable solar sailing is possible. Now it's time for the next chapter in the LightSail's continuing mission. We need to educate the world about the possibilities of solar sailing by sharing the remarkable story of LightSail with scientists, engineers, and space enthusiasts around the world. We're going to publish a commemorative book for your mission.

It will be filled with all the best images captured by LightSail from space, as well as chapters describing the development of the mission, stories from the launch, and its technical results to help ensure that this key technology is adopted by future missions. Along with the book, we will be doing one of the most important tasks of any project. We'll be disseminating our findings in scientific journals, at conferences, and other events, and we'll build a master archive of all the mission data. So every bit of information we've collected will be available to engineers, scientists, and future missions anywhere. In short, there's still a lot to do with LightSail, and that's where you come in. As a member of the LightSail mission team, we need your support to secure LightSail, and that's where you come in. As a member of the LightSail mission team, we need

your support to secure LightSail's legacy with all of these projects. Visit planetary.org slash legacy to make your gift today. LightSail is your story, your success, your legacy, and it's making a valuable contribution to the future of solar sailing and space exploration. Your donation will help us continue to share the successful story of LightSail. Thank you. So when you actually do these tests, I mean barring all the differences between them, what is kind of the structural difference of these craters versus the craters we see on the moon or Mars, something that's less metallic? So what I can say now, it's based on this understanding that we are building from experiments, right? So these are lab scale experiments. So imagine the craters

that we are producing are not huge. So you have to keep that in mind when we try to make a comparison, say for instance, for craters on the moon or other celestial objects, right? Those craters are much, much, much larger than what is produced in the lab. So having that said, we can compare impacts, you know, all craters produced in the lab. So we can compare crater produced in the lab. So we can compare crater produced in an iron meteorite with crater produced in a piece of rock. And they look very, very different at the lab scale. And the primary reason for this is because the metal is much, much harder than any rocks. In fact, typically these iron meteorites are hundreds of times harder than any rock, say a basalt for instance. So it takes much more energy to break them up and to excavate and produce a crater. Well, that results in two interesting outcomes.

Well, first, it's perhaps the most obvious for the same impact energy, the crater on a metallic target is going to be much smaller, obviously, because it's much harder to make a dent. But the other aspect is that the way the material, the metal behave in this high energy event, you have to imagine that you, it's like having an explosion, the material starts to flow and move around and eventually produce a cavity a crater but the way the material flow uh it's different so a metallic material flow in a different way than a rocky material and so what this brings us to it's a very peculiar morphology some of these creatives metal, if you look at their floor, the bottom part,

they contain what I like to call like petals structure. A little thin sliver of metal arranged radially in a very symmetric way, which is very nice to look at. But this is something that you will never get in a rocky material. And the other aspect of interest is the rim of the crater itself. In a rocky material, the rim typically is shallow and it sort of crumbles easily and it collapses easily. While on metal, we find these raised rims that are basically very sharp. You can imagine the metal as it flows and it tries to leave the crater, it basically freezes in place, leaving the sort of blades sticking out the surface at about 45 degree angles. And they just sit there. And they're

very hard. And if you move them, you try to break them apart, they're not because metal is hard. So all of a sudden, at least at this lab scale, we would definitely see weird morphologies. Something that would be just unthinkable of any other rocky material. Now, as I said earlier, the big question is whether or not this morphology that we see in the lab, it's then applicable to much larger scales on an asteroid. So that is something that remains to be seen. Most of the art of Psyche depicts these kinds of jagged, almost knife-like edges coming out of these cratering situations.

Were those images created prior to these tests, or is that still something that we think is the case? I believe that these things were coming together pretty much at the same time. I think that some of those sharp edges that you see in some of these wonderful renderings that we have for the asteroids come from looking a little bit at this early batch of experiments that we did, in fact, where we started realizing this aspect of these raised rims and these petal structures in the floor. So yes, in a way, they came together.

So I think that those renderings are still a viable realization of what Psyche might be. It occurs to me that it's not just the asteroid itself that needs to be modeled physically by using these meteorites, right? But the things that are actually going to be impacting Psyche themselves are going to be these objects from space. So were you using bullets and things like that to shoot the meteorites or did you make bullets or projectiles out of other meteorites to get like very accurate? No, regarding the impactor, there were simply beads, you know, quartz beads.

The reason is because it's the easiest thing in the lab to manufacture and they are well known in terms of properties and and that provide us with very nice consistent material for these experiments. Now when it comes to real impacts in the asteroid belt where Psyche is comes to real impacts in the asteroid belt where Psyche is we can certainly imagine that you know for the vast majority of the impactors would be rocky asteroids because that's what's what's happening in the main belt you know most asteroids are rocky there are very few asteroids that are not rocky in the main belt and so the impactor natural will be rocky so the fact that we use

quartz in a sense is sort of you know it's not of course what we find in space but it's sort of similar and and one other thing to consider is that the impactor material plays not much of a role in the outcome in the sense that the impactor is completely destroyed and vaporized upon impact because of the energy. And so, you know, the specific nature of it doesn't necessarily alter the outcome. Unless, of course, you go completely wild and you take a metallic impact, well, that would be different. So now we've done all these experiments, we've got these computer models, we have art, we think we know what this is going to be like,

but what kind of things do you think we could actually learn about the early solar system or planetary formation by studying this body? There is growing evidence and consensus, I think, in the community, in the planetary science community, that in fact the main belt, which is a structure between Mars and Jupiter that contains millions of asteroids, all of those asteroids or a large fraction of them may have formed elsewhere in the solar system. So they necessarily didn't form where we find them today. So a fraction of them could have formed much closer to the Earth and then been implanted into the main belt where they currently are. And likewise, the fraction of them

may have formed in the outer solar system, and they have been implanted into the main belt. So think about this process as the main belt is sort of a melting pot of objects coming from all over the place in the solar system. Now, that makes it interesting because how about Psyche? Is it perhaps an object that formed there or formed in another location of the solar system? And so this gives us a little bit of an opportunity to try to understand the composition and the properties of these objects may reveal some of these early processes of

transport across the solar system. And that's one aspect that I'm particularly interested in. But there are other things as well, like we mentioned earlier. If this is a core of a differentiated planet as well then will give us a unique opportunity to study the guts of the interior of a larger object and that would be a unique opportunity you know we stand on earth we know there is a metallic core below our feet down in the earth but we cannot really see it and and so here we have an opportunity where we can possibly see something like that wouldn't that be fascinating?

I mean, it could tell us a lot about our planet and others. Having an opportunity to study an exposed planet core might be one of the most, forgive me, metal opportunities. Heavy metal opportunities. Does your team make a lot of jokes about that? Because I know we do. Yes, a lot. So Psyche is finally out there. We have all these ideas about what we might find when we get there, but it's going to be a little bit. The spacecraft is going to be traveling through space. So what's

the timeline there? When can we start expecting the first data coming back from Psyche as it approaches the asteroid? Oh, that's going to be shy of 60 years for now. That's how long it takes to get there. Before then, we'll have a gravity assist with Mars. So that will be also an interesting event. And there will be many other things happening between now and then. But regarding Psyche, the first data will come in a little while. Just mental image, Psyche cruising by, high-fiving Mars Reconnaissance Orbiter, you know, saying hi to Hope and then cruising on out into the asteroid belt. Yep.

What is your team going to be doing in the intervening years as you wait? I bet you can guess the answer. I will be doing more of the impact experiments, that's for sure. Because it's fun, because there is an opportunity to learn things that we don't know. And in fact, as we do these experiments, we generate new questions that we didn't even think about it. And so that's been a very interesting twist. And I'm not a lab guy by training or nature, right? So this is also new for me. So I like it. I like to face new challenges.

And so this will be an aspect that I'll be interested in. And of course, we will also plan for all the modeling that's needed in order to interpret what we find on the surface. So one of the things that I'm keen on is to look at the craters, have a good sense of their distribution sizes. That is in fact fundamental information that we can use to then try to infer the past evolution of the asteroids. So for instance, how old is a given surface?

We can try to assess that by counting how many craters we have on top of that surface. And with models, we can get to the age question, which is very important. And so all of those things will happen in parallel between now and then. I would love to be a fly on the wall during those tests. I'm wondering, have you guys taken slow motion video of these impacts?

Because I bet that would be really cool. We actually took fast motion videos. Oh, wow. We have cameras that are high speed cameras that can take up to a million frames per second. Can you imagine? For each second, you have one million pictures that are taken. And that's needed in order to be able to see what happens because everything is super fast in these experiments, right?

And so that's the kind of instrumentation that we need. NASA Ames facility that we utilize for this is equipped with state-of-the-art high-speed cameras. And so all our experiments have been filmed from various angles, various illumination conditions with this equipment. And so, yes, we do have wonderful videos that shows what happened in these collisions. Are there any places online that people can watch these videos? There might be. I believe some of these videos were shared early on by ASU in some of their outreach activities and blogs and other locations on their Psyche website. So, yes, I believe some of them at least are accessible on the web. Well, I know what I'm doing after this conversation, Googling that.

Thanks so much for joining me, Simone. This is just an absolutely mind-blowing conversation. And I hope you have so many more adventures just firing things into meteorites. It's amazing. Well, thank you so much for having me. It was fun. And again, congrats to you and your team. That launch was fantastic.

Thank you so much. Until next time then. Some people have the coolest jobs. We'll hear from Simone Marquis again in an upcoming show about the Lucy missions rendezvous with asteroid Dinkinash. Now let's check in with Bruce Betts, the chief scientist of the Planetary Society, for What's Up. Hey, Bruce. Hey, Sarah. I continue to be amazed by seeing you and other people around the office during our co-working week. It has been a good time getting to see your face.

It's been wonderful. It's been wonderful. And now it's over, so go home. No. Oh, sorry. Sorry. Didn't know. Okay. Never mind. No, it's true though. I like being here in the office, but it won't be the same without all y'all. So, but a good time. It'll be better. It'll be better. I'll actually get work done.

No, it's been great having the whole Planetary Society staff from all corners of the world. Well, okay. All corners of North America coming together. And I just had this kind of awesome conversation with Simone Marquis about firing things into meteorites to test how craters form on metallic asteroids. I mean, that's a wild job. That's so cool. Yeah, yeah. No, I've been friends with people who do impact lab experiments, and it's pretty crazed which is very cool it just never occurred to me that you would need some kind of ridiculous high-speed gun with awesome cameras designed to capture the impacts but i understand you have some experience with these tests not at the i'm at the edge of these tests uh but not in involved in them So I had a good friend, office mate, who used to do the light gas gun in the basement of the Caltech Plantary Science Building.

And I forgot, but they get speeds like five, six kilometers per second. And it's pretty cool noise when they hit all the metal plates designed to slow the target down. the metal plates designed to slow the target down. And then, you know, for impact cratering, that was more studying phase diagrams of various types of iron mixed with other stuff to do planetary interiors. Then you have things like the Ames vertical gun, which actually people have done all sorts of experiments over the decades and shooting stuff and watching what happens. It's cool. All I do is throw rocks into a pile of sand, but I love those experiments.

And once upon a time, I did some crater studying work on Mars, and so I actually was trying to understand the impact stuff. You know, it's technical term. Impact stuff. It's funny because I've never fired a projectile in my life or gone to any kind of like range for doing that. But you say, here, come shoot some quartz pellets at some meteorites. And like, I want to go to there. Well, sure. Yeah, we did impact experiments officially and unofficially in my days at Caltech,

including cheese. Cheese? We did impact experiments on cheese because, you know, the whole could the moon be made of cheese thing and or at least that's our justification. Never mind. Let's move on.

What else you got? No, no, no, no. Was this for like an April Fool's Day paper? Like what? Oh, no, there was no paper. That's amazing. No, turns out the moon not made of cheese. So the research was purely recreational.

That's hilarious. Awesome conversations about awesome space stuff. I don't know. It feels like a weird point in history to be at this turning point. We're about to go to a metallic asteroid. It might be the core of a planetesimal or something. And here on Earth, we're just celebrating with computer models and firing things at other things and just making awesome art of what we think it might look like. And I bet it's going to completely blow our minds when we actually get to Psyche.

This is planetary science. This is what you do. You do what you can on Earth, and then hopefully you get a spacecraft going to where you want to go. And then you get your minds blown, and you figure out what you got right and what you got wrong. And usually, no matter how hard you work, nature surprises you and you got more wrong than right. But it depends. It's funny because like I went into astrophysics thinking, ooh, pretty space pictures. Like, I want to focus on this. The planetary scientists, y'all have all the really weird adventures. Like, I'm going to go to Antarctica and collect rocks. I'm going to...

adventures. Like, I'm going to go to Antarctica and collect rocks. I'm going to... Yeah. Well, some of us just stare at computer screens with them. So what's our random space fact this week, Bruce? Well, I'm still stuck on the Lucy mission and things derived from that. So when we're recording this, they're just about to do their first asteroid encounter in the main belt asteroid. According to this, they're just about to do their first asteroid encounter in the main belt asteroid. But their main goal of the mission is to be the first time studying Trojan asteroids of Jupiter, which hang out 60 degrees ahead and 60 degrees behind Jupiter at Lagrange gravity balance points.

But no. You didn't actually say random space facts. Or did I? Did you? Was it just so fast that you missed it oh no let's redo it just in case because otherwise i will be very embarrassed oh random space fact nailed it random space fact is tied to these jupiter trojan asteroids there are a lot of them there are many many at least thousands if not hundreds of thousands, that are like over

a kilometer or two in size. And they've discovered they're pushing around 10,000 order of magnitude of these Trojans. But the mass, it's like the asteroid belt, the mass is very, very low. And so the estimated total mass, although it's got a typical planetary science factor of two, three error bars, is like one-fifth the mass of the asteroid belt. But wait, the asteroid belt, despite having millions of things, is estimated to have a mass, which I have mentioned before, of, depending on numbers, vary by a percent or so, but around 4% of the moon, the Earth's moon, is all the mass that's in the asteroid belt, and 20% of that in the Trojan asteroids of Jupiter. So there you go. So you're not going to scoop it all together and make a planet,

is the bottom line, or at least not a very good one. You could scoop it together and make one slice of cheese. And I can tell you, if you impact that cheese with, never mind, it was cheddar, but there's still a whole open field of research to look at different types of cheeses, but that's not important right now. Trojan asteroids, very cool. We'll get our first view of several of them from Lucy when it gets out there right now in the inner parts of the main asteroid belt. And we will be talking to the Lucy team in the future.

After the flyby, once they get the first data back and do their first little analysis, we'll have them on the show. So I'm looking forward to that because Dinkinish. A new world. Woo! A new world, new place, new pictures. That's awesome. It looks like a potato. They all look like potatoes. We were having a conversation the other day about which planet looked yummiest or which moon looked yummiest. Wow. Io.

Right? I mean, Io looks pretty tasty. As long as you don't know what it's actually made of. I mean, I wouldn't eat any of the moons, frankly. Just important safety tip for those at home. But Io, it's got that pizza thing going on. Right. I feel like Jupiter looks like it would make a really good ice cream. Well, as usual, you've thought this through far more than I. I have to say, we had some really lovely comments on your random space fact last week. People loved the Lucy reference and understanding that name.

So one of our members, Craig Griffin wrote us to say that he loved the Lucy reference and from a space mission to a fossil, to a Beatles song reference and to an English woman, like beautiful trajectory. Nice arc. Yeah. No, it's got more of an arc than pretty much any mission name I'm aware of.

A lot of good stories. All right, everybody. Go out there. Look up in the night sky and think about Vikings eating aisle pizzas and finishing it off with some Jupiter ice cream. Watch out for that brain freeze, everyone. Come back next week. Thank you, and good night. We've reached the end of this week's episode of Planetary Radio,

but we'll be back next week with Lindy Elkins-Tanton, Principal Investigator for Psyche, and our partners at The Eclipse Company on their new Eclipse app. You can help others discover the passion, beauty, and joy of space science and exploration Thank you. Also send us your space thoughts, questions, and poetry at our email at planetaryradio at planetary.org. Or if you're a Planetary Society member, leave a comment in the Planetary Radio space in our member community app. Planetary Radio is produced by the Planetary Society in Pasadena, California, and is made possible by our curious and creative members. You can join us as we nerd out over worlds no human has ever seen at planetary.org slash join. Mark Hilverda and Ray Paoletta are our associate producers. Andrew Lucas is our audio

editor. Josh Doyle composed our theme, which is arranged and performed by Peter Schlosser. And until next week, Ad Astra.