EVSN - After Hours #8: Making Moons & Getting Cratered With William K Hartmann

Introduction of planetary scientist Bill Hartmann

0:00It's the 365 Days of Astronomy podcast, coming in 3, 2, 1.

0:30Hello, everyone, and welcome to CosmoQuest After Hours. Now, if you're saying to yourself, hey, I'm in the United States and I'm still at work, we understand. The world, it's round, and it's already after hours in the EU and Africa and the Middle East and eastward from there. So, this is After Hours UTC Plus Zero Edition. My name is Dr. Pamela Gay. I am the leader of CosmoQuest and the host for today. I am super pleased to have on someone who really inspired me

1:10when I was young and then ended up being one of my colleagues now that I'm not as young. Specifically, I have joining me today, Dr. William K. Hartman, a planetary scientist, a space artist, and one of the founders of the Planetary Science Institute. Welcome, Bill. It's wonderful to have you on today. Good to be here. You have a career that literally spans planetary science going from the

1:44study of things that are slightly bigger than point sources in the sky to being able to explore other worlds and take samples and take up close pictures. You, I think, graduated high school about the same time that Sputnik launched, give or take a year. That's right. It was, in fact, when I went from high school to Penn State as a student, October 4th, I was going down to the place where we had breakfast,

2:22you know, and they had New York Times that were selling in those days, and the headlines were all this big Soviet satellite in orbit, and that was an amazing thing. And that was just kind of the beginning. And there was a kind of joke going on because we had been trying to get a satellite up also and hadn't done it. Both the Russians and the Americans had captured German rocket scientists.

2:58And so this space race was on, but the space race, the joke was that the space race is between our German rocket scientists and their German rocket scientists. It's true. And this leads to a lot of fascinating commentary today, but it was a completely different time. And one of the things that gets me about your career, something that I always go back to is in 1962, when Mariner 2 flew past Venus,

3:29that was the very first time we ever were able to directly measure a quality of another world. And in that moment, we went from seeing Venus as potentially a tropical paradise to realizing it had a temperature of approximately 800 Fahrenheit or 425 degrees Celsius. And with that discovery, we also saw many, many science fiction writers suddenly change what they were writing about Mars and Venus as

4:03they realized, no, that no, our fictions are no longer possible. What was it like to be in school and picking your dissertation topic and things like that, while we were literally rewriting our entire understanding of the solar system?

Studying planets with Gerard Kuiper

4:20You're right, it was really the beginning of a whole new era. And in a way, I really was lucky and benefited from that because there were so few of us that were interested in this. And my professor in graduate school, once I got to the University of Arizona and arrived here in 61, was Gerard Kuiper. And he was one of the very few astronomers that was actually interested in the planets. Yeah. There was another kind of joke

4:55among astronomers that they didn't, they really didn't like the moon because the moon was this big, bright thing in the sky and they couldn't be there. They were studying very faint, distant galaxies.

Proposing the giant impact moon formation theory

5:06It's true. It is our enemy. You early on were able to be part of pioneering how we started to understand things as we got more and more data. And early on in the 40s, it had started to be speculated that the moon formed either through some kind of, actually dating back to the 1800s, some sort of a, the earth was spinning so rapidly that a chunk flew off, an angular momentum argument.

5:42But then in the 40s, we started to see arguments that weren't well popularized, even within the professional community saying, well, maybe there was some sort of a collision. And in 1975, or was it 74 that the paper came out, you and Don Davis presented the idea that it was definitely a collision of a Mars sized object. What inspired you to start thinking,

6:16we live in a very violent solar system and violence can be creative?

6:24George Kuiper was a kind of a father of the planetesimal theory that the solar system, when the sun was forming, and we've seen this in other young stars also, a disc of dust and gas around it, with particles beginning to become solid. The same idea that, you know, when water vapor goes up high in the atmosphere, I mean, it can make raindrops, but if it goes higher, it makes a solid

6:55object. So that's what was happening. So these things were beginning to collide, because they're just forming everywhere. And when they collided, they were often sticking together. That's kind of what I was getting from Kuiper being a student of his. And the more we learned about in the next few years, say in the 60s, when I was a graduate student, there was a there was an argument until about 1960, that the craters on the moon were volcanic. And then the other argument was no,

7:33they were asteroid impacts. And I think volcanic was winning out. But around 1960, particularly in Canada, they began to have a lot of these little round lakes, kind of circular lakes. And it turned out that they began to pick up meteorite fragments around a lot of those, that they were obviously meteorite impact craters in Canada. And that helped to turn the tide that the moon craters really are impact craters. So once you have that settled, then there's a lot more credibility to the idea that

8:11as the planets were forming, there would have been a very high impact rate, you're getting craters forming all over the place. And if one of the objects, which were called planetesimals, they were really like what we call asteroids today. But if one of those grew large enough, and then in our neighborhood, maybe crossing the Earth's orbit, if it crashed into the Earth, it could throw off a lot of material from, and this is important, from the outer layers of the Earth. And there was already

8:49information that the iron core, the inside of the Earth, which had been growing, was very hot. And the molten metals, the iron, went down to the center. So we have a big iron core in the Earth. That means that the outer layers of the Earth are a more rocky material. And that seems to be what the moon is made of. So that sort of fit. I mean, a lot of things began to fit together when you think about just blowing some material off the Earth, getting it into orbit, big cloud, or eventually a

9:23ring. And the particles in that ring start colliding together and forming a material. And the bigger, the bigger the biggest one gets, the more it gets to a point of its gravity is attracting the smaller ones. So the bigger ones grow. And so the moon eventually comes out of that. In coming up with this theory, you and Don and collaborators were working at a time that for

9:53folks like me, it's very hard to imagine. You didn't have the ability to just spin up a computer model that would demonstrate to the world that yes, the math on this works. How did you work through all the math without a computer? I don't know how to say it any other way. Well, Don Davis was an expert in orbits and orbital theory and so forth. So he incidentally was on the

10:24team that brought back Apollo 13 when it had an explosion. And they had to give up the landing and send it around the moon and bring it back to Earth. And he was part of that team. So he was an expert on that, which I wasn't. So I went to Don and said, you know, if you, if we're, and there were several of us that were interested in asteroids at that time, but Don was the one who really understood orbital aspects. And so if you had enough of the small particles creating asteroid-like objects,

11:00is it plausible that you could get something fairly big in years, it would be near the Earth's orbit that would eventually hit the Earth. And so he did some of the calculations. And I think we were just coming out of this, coming out of the slide rule era. Downstairs in the, here in the PSI building, where I am, we have a little display case. And one of the display cases is some of our original slide

11:30rules that we use. But there were beginning to be calculator, calculators. So, but they, you know, the theories were there and the ability was there to look at how these things could grow. And so that's what Don was doing. And, and so he and I, I asked him to be a co-author on this thing. And, and we gave a talk in Cornell, I guess it was their conference. And then the next year was 90, it was 74. We, that, that

12:04was in 74. And then the next year was 75 when our paper came out. Now, I think I got that, I think I'm one year off on that. But anyway, that's, that's the sequence. Now, they have since gone on to name the thing that smacked proto-Earth Thea. Did you get to have any say in how it was named?

12:27No, that popped up in somebody's article. I wasn't too fond of it, because my idea was you, you, we shouldn't give a name to something that we still don't know whether it really existed or not. That, that bothered me a little bit, but, but that name stuck. And so, uh, it's often used.

Collaborating with Soviet space scientists

12:52Now, your entire early career was in large part defined by the Cold War. There was Sputnik marking the beginning of your university. There was Yuri Gagarin. There was the race to the moon. And there were a lot of people at the time that gave into the competition, gave into communism being the enemy. And one of the ways that I first encountered you was, was through your space art.

13:28So this is a book that I got in seventh grade. So 87 me found this when I was a baby astronomer. And then in 89, I went to the Soviet Union as part of a peace exchange trip, uh, where they, they were sending top science students from both nations back and forth. And when I came back from that trip, everyone was like, and now we shall get you U.S. Soviet stuff for all the holidays.

13:58And so in 1990, I was gifted this book and I've been carrying these two books around with me, literally my entire adult life. That's the one that has the, some of the Soviet artists in it. Yes. Yes. That, that, that period in the nineties was wonderful because we could just go over and visit with them, work with them. I mean, I worked with other artists. I worked with the scientists. I worked with some of the writers. They were all, you know, this is great. We're

14:31working with the Americans. I had a kind of a touching event. We had been working on something that would go in. I think the Russian rocket and we were, it was partly our, our instrumentation and theirs. And we were getting together with them and just outside of Moscow. And so on the third night we had to have a, uh, big, um, dinner. So the first thing that was amusing was we came into the room and there's a long table, maybe 10 people on each side and sitting on the table were bottles

15:07and starting at one end, it was a vodka bottle and then a Pepsi bottle and then a vodka bottle and a Pepsi bottle all the way down the table. I have been at dinners like that. It was amazing. And for whatever reason, Pepsi was much more in the Soviet Union than Coca-Cola. I don't know. I guess they got there first, but then there was a guy sitting across the table from me about 35. And, uh, after about the three vodkas, I think, you know, he kind of perked up and said, uh, you know, Beale. They think that's the way they pronounce my name, Beale.

15:42Three years ago, I was working on things that went into the tops of the rockets and those rockets were all aimed at you people. And he kind of paused and it was very heartfelt. He said, I would much rather be doing this, putting things that go to Mars and working with you, you know? And, uh, and we've kind of retreated back from that now. So it's difficult, difficult for me because I know some of these people. Yes.

16:12I had one Christmas card from one of the ladies scientists that we worked with. She and her husband invited me and my wife, Gail, to a trip to St. Petersburg. So we were friends and she said, I'm afraid my country is committing suicide when they had, and they had just invaded Ukraine. So, I mean, the ordinary people in Russia don't particularly like this. I'm kind of a fan of the

16:43Russian jokes that I heard. And there, a lot of them are kind of secret, secretly critical of the system. So difference between a pessimist and an optimist. Well, the pessimist sees the dark side or everything. So things are terrible. It can't possibly get any worse. But an optimist sees opportunity everywhere and joyfully says, yes, of course, things can get worse. They can get significantly worse. Yes. And then I would have a sort of rush of humor. Oh, no, I'm not talking about the government. I'm

17:14just making a joke. Well, then that's okay. Yeah. I have a sticker along those lines on my iPad that says, don't worry, tomorrow will be worse. And yes, it's a very Soviet sentiment. And so it sounds like he must have been there right around Kospar back in 2015 when Crimea was invaded. Is that about the right timeline? Yeah. I think that was, we were still not friends with the Russians during that period, I think.

17:46And it seemed to me it was like 89 you talked about. Yeah. So 89 through the early 90s was Perestroika. In August of 91 was when the Soviet Union collapsed and fragmented. And we saw Yeltsin become president. And there was the coup to remove Gorbachev. And it was in that era in the 90s that we saw this radical change from the U.S. International Space

18:27Station, not international, the U.S. Space Station freedom that was being planned at that point to getting multinational crews on Mir and beginning to re-see the International Space Station as something that was a U.S.-Russian collaboration in this new world that we were trying to figure out how to define. And it's easy to see it on the aerospace side. You saw it on the art side as well. And here I

19:00need to bring up some of your art to show everybody. And this seems like a natural one to start with. This is from 1999. And I see it as the formation of the moon from that early collision with just this dramatic sun in the background. And incidentally, if you look in the sun, you can see at an angle what's called the zodiacal light. Yes.

19:30And that, if you look at the evening and the sun has gone down, you can often see that it kind of looks like the Milky Way, but it's the dust in the solar system in the disk of the solar system. It was studied by Queen guitarist Brian May for his PhD dissertation, which is one of my favorite random facts. And one of the things that got me about a lot of your work is you saw this

20:03collaboration going into the future and you saw humans on Mars. This particular painting, it shows two different capsules, at least six different human beings. What did you imagine when you were painting this? Well, as I said, it was an idea that I had that they would land, the one in the distance, that ship that's in the distance is landed robotically. And then the bigger closer ship is

20:37the one that comes down next and has people in it. But the first one has supplies and then it serves as a backup ship. And then, as I said, if it didn't go out in the audio before, that painting is precisely a view down in this Mexican lava area. It's called the Pinacates and the Pinacate Mountains. That shows what was actually there, except I took out all the bushes and the plants. So that area in

21:13the Pinacates was so similar to lunar and Mars areas that they trained the Apollo astronauts there. And there's a place I've been to, I'm not sure I could find it again, but where one of the astronauts carved his name in one of the rocks. That's amazing. And it gets me that you were seeing that geology here and geology across all

21:46the different worlds, it has the exact same physics. It just plays itself out in slightly different ways. And you were capturing that in your artwork and creating worlds that we didn't know we were going to one day discover are actually fairly real. So for instance, back in 2008, 2018, you created this small body, minor planet that really looks to my brain like the Millennium Falcon. Every time I see it, I do a double take. I need to know the story behind this and what it is

22:21that causes you to create such shattered planets that still hold themselves together.

Discovering elongated asteroids and planetary shapes

22:29Well, in graduate school, my best buddy, Dale Crookshank, ended up going to Hawaii. And as a result, he had access to all the telescopes on the top of Mauna Kea. That was an observatory that Kuiper wanted to establish. In fact, he sent me there to drive up to the top when there was nothing but a small telescope at the top to do testing of the site. So Dale and I did a lot of observing

23:04on Mauna Kea when it was just being realized that a lot of the asteroids were not just nice round bodies, that they were somehow elongated. Yeah. And, you know, if you have an elongated body, if it's elongated and it's rotating, it'll be dim, and then it'll be bright, and then it'll be dim. You can't actually see the shape, but you see the light curve, as they call it. And there were some asteroids that had very big light curves. And Dale and

23:37I, we looked at one of those, and he came up with a brilliant idea to use an infrared telescope and a regular telescope at the same time, two different domes on Mauna Kea. And the reason for that is that there is a body in the solar system that is just dark on one side and light on the other. It's Iapetus. I think it's a satellite of Saturn. So it's round, but as it turns around, it's dark and it's light, even though it's round in shape. So the question was, is that what all of

24:12these light curves were about? Or could we prove that the thing was elongated? Here is Iapetus. Oh, yeah, they're okay. There it is. So you see, there's a really dark side on the right there, a dark patch. So when that thing rotates, it gets light and dark, even though it's round. Exactly. And so that was the question about asteroids, were they all really round and just had these dark markings on them? And what we did was use the infrared and the visible at the same time.

24:44So if it's dark, if the dark side is facing you, it's emitting dark infrared light, the thermal heating. And so it'll be bright when the dark side is there. It'll be dark through the visible telescope, but it'll be bright in the infrared. And we were able to prove that no, what was really going on was it was elongated in shape. So that it was, when it was bright in visible

25:17light, it was also bright in infrared light. And when it was in dawn, it was dark in both. So anyway, we did that. It's now, I mean, it's now known that these things can be elongated. This particular picture was Mike Belton, the late Mike Belton was working on one of the, I think this is one of the first things that came through the solar system at very high speed. And it was from another planetary system, apparently. He had the idea that it could be flat rather than

25:55just elongated. And so he asked me to do a painting that would show something like that. And so that's the origin of that painting. But so that's a muamua is, is that object? Yeah. And of course, when Arthur C. Clark had written a story about something coming into the solar system, just like this, but when they sent some people out to look at it, it was actually an alien spaceship. Every time one of these comes in, you know, as well, could it be an alien?

26:26Spacecraft of some sort. But so far it's been three of them and none of them are alien, empty alien spacecraft. It's really interesting. And what is cool about your perspective on things is you got to start looking out at the solar system, even before the Voyager missions. And then as an adult, take inspiration. This is a favorite for many different people among your art, where you see

26:57this just Saturn with the perfectly edge on ring, highlighting just how thin those rings actually are, while seeing the cracks and the chaotic terrain and the geysers that we were just starting to understand were actually there on Europa. What has been the most striking discovery in our solar solar system to you so far? The thing you least expected to learn in your lifetime?

Organic molecules and the late heavy bombardment

27:29Well, we just recently have picked up some evidence of molecular, not living material. But organic, molecular organic material. Yeah, that's right, on Mars. So there's really some hope that there might be some evidence of very early life on Mars or just molecular life or single-celled things.

28:00This one was another Mars painting, and it was an interesting event that there was

28:08an asteroid that had broken up, and it was going close to Mars. And so there was probably a meteor shower on Mars at that time. So I was trying to just take a kind of a random Mars landscape and then these shower of things coming into the atmosphere. So that's the origin of that one. It's a really cool image. And it reminds me of one of the things I wanted to bring up. Throughout the years, I came to planetary from astronomy. So I've had a whole lot of,

28:43what do you mean? Just trying to understand weird stuff they don't teach you in astronomy classes about planetary science. And one of the things that really confused me was this idea that our solar system, when it first formed, had the worlds in roughly the order they're in now, but in very different places. And through various interactions, they moved each other. That part, so far, so good. But the part that threw me was this idea that there was study bombardment,

29:18bombardment, bombardment, bombardment. And then there was this epic period of what is called the late heavy bombardment. And my brain broke. And talking to you has made me feel slightly more justified that my brain broke. Because you've actually been thinking about this from the science side, and you're not entirely convinced about the late heavy bombardment. And I'd love to hear your thinking with that full perspective of how we've come to terms with all of these discoveries.

29:52Well, going back to the beginning, as I said that we were hearing Kuiper talk about the planets growing with all these planetesimals coming in. So it just seemed obvious and natural that the planets would be intensely cratered, intensely impacted by lots and lots of things at the beginning. And gradually, you're using that material up in the solar system, the stuff close to the Earth eventually hits the Earth, and stuff near Venus hits Venus. The only part left is the asteroid belt,

30:25and also some belts out in the outer solar system. That, to me, seemed like the obvious thing. So the bombardment stops up here. I mean, starts. The planet has formed. You're running out of material. So the impact rate just goes smoothly down, down, down to where we are today. Now, what happened was that the people who were selected to study the samples that came back from the Moon,

31:02they were dating the lunar samples, in particular by some minerals that are formed during impact, during the very high pressure of the moment of impact and the explosion of the rock. So there are these impact melts. In other words, it's something that gets melted briefly and then forms a new mineral. Those were the things that were especially being dated by the people who looked at the samples. And they were, several of them, and Jerry Wasserberg was a great example. I mean,

31:39he had a good sense of humor. It was kind of a coarse sense of humor. At that time, I had been using the numbers of impact craters on the Moon to estimate the age of given surfaces. And he was invited to University of Arizona and gave a talk. And in the talk, I suspect he knew I was there and knew, well, he must have known about some of my work because he, in the middle of his talk, he said, he said, so, you know, we can date these things. This is ground truth. So you can,

32:13you can drop all of the, the crater counting stuff down the toilet, you know.

32:21And so we are still crater counting. If anyone needs to crater count, we have new data added to our lunar melt project, which is specifically looking at craters in lunar melt. So go check out mappers.psi.edu. Sorry for the PSA. Continue. So, so you're, you're in the audience as like an intellectual sniper waiting for the right moment. I didn't say anything about it though. I mean, he got his laugh and, and, uh, but I've talked to,

32:52I mean, I've been in friendly terms with him and later on, and where I'm going with that is that when they, when they were looking at these impact melts, they went back to about 3.9 billion years ago. And then, and the planets were known to, are known to have formed at 4.5. So there, there was this 600 million years when there was hardly any impacting, which didn't fit with my, my, my ideas at

33:25all, uh, uh, my sense of the universe, but there was ground truth to them. And so, so this was this late heavy bombardment. In other words, there wasn't much bombardment. The planets formed, then there was no bombardment. And then there was this big peak of bombardment. So their curve, uh, the curve looks like this. There's over here, there, there was hardly anything. And then there's a big source of impacts. And then it decreases from there. I, uh, I think that that is still very uncertain

33:59and probably unlikely. I joke around that about every 10 years, I write a paper about this and why, why the late heavy bombardment didn't exist and nobody pays any attention to them. But in, in, um, 2000, there was a group here at University of Arizona that were beginning to be able to date very tiny fragments, uh, in the, the rocks. Yeah. They didn't need the big impact milk piece of mineral. They published a paper, the friends of mine. The title of the paper was that this was

34:37support for the, uh, big impact theory, the late, late impact. And what it was, was, uh, they, they had their curve was coming down and, and then goes up at 3.9. So that's the big, and then it goes down again. But then there's other little curves in there that weren't in what Wasserberg and so on. So I think those other curves were some of the later big impacts on the moon, the big, uh,

35:10Mari, uh, basin forming impacts. So they said that this was support for this, but to me it, it was, no, it was, in other words, it wasn't, it wasn't one big peak like this and then just goes down. It's a big peak and then it goes up and it goes down and it goes up and it goes down. I think still that there was probably a very intense impact at the beginning. And that also is important to understanding the upper layers of the moon,

35:46because we know there's a layer of what's called regolith, fine dust and particle, fragment particles from, from the, the kind of a sandblasting that the moon is getting all the time nowadays. But at the beginning there would have been much more just just for destruction of say the very early lava flows and the places where the early impacts were would be all ground into fine dust by this intense impact. So, so in my mind, the intense impact is the solution to this.

36:22There was a fellow named Jack Hartung, who was a pretty much plain geologist, but he, he wrote lots of interesting papers on different topics. And he wrote a paper around that time pointing out that just very simple-minded paper, you know, that if this is the impact rate, if there is any process in the early 600 million years that destroys things,

36:52then you, you get this big peak, some period of time when that ends. And he just said, you know, you can have a, the late heavy bombardment could just be the running out of the intense bombardment that was destroying all the early pieces of this. So that's what I think really happened. My sense is, you know, I'm not very active in that field anymore. It's because I'm theoretically retired, although I like to keep working on things. But my sense is that the theory that I have been

37:30promoting is catching on slowly. I talk to different people and I say, you know, do you feel like this is beginning to take hold? And some of them do. And well, no, there's a lot of people who still think it's about one big, late heavy bombardment. So that's where we are now. It feels like there's always a piece of art to hold up the ideas. One of the things that really resonates with what you're saying is we've been discovering over and over that worlds are fluffier.

38:04And that's actually the word they're using periodically. Worlds are fluffier than predicted. So Jupiter's core is fluffier than predicted. There was work on Titan that came out, I think, last week that it's fluffier than predicted. And so we're finding more and more evidence for planet-on-planet collisions and violence and massive impacts. Vesta was smacked so hard, it has wrinkle ridges around its waist. We find evidence on Mars that there's potentially

38:44hemisphere-sized differences between the highlands and the lowlands.

38:51What kinds of evidence would be needed to start to say that, yes, there were massive resurfacing events that occurred because things collided with each other. But there wasn't a late heavy bombardment that was generalized across the solar system. That actually begins to sound to me like our ideas because this fluffiness is presumably the grinding up of a lot of the material. And that's

39:22that's this very intense bombardment at the beginning. The term regolith, we were using a term of, well, it's kind of super regolith. If there was this early impact, there would be layers down below 50 meters or a kilometer. The upper kilometers would have a lot of this except that that can weld together into rocks that are made of the different particles. So I think maybe that's what they're seeing. I'm not sure.

Lunar regolith and early impact layers

39:58Now, this reminds me, back before we actually landed anything on the surface of the Moon, Fred Hoyle had concerns that we'd try to land, and there were predictions like yours of the regolith. And the concern was the spacecraft would just sink through this silt.

40:21How did it feel to see we're not actually sinking, but there is this really sharp dust that covers the surface? And remember, there were several landers, unmanned small landers that were looking for that effect. And it was very important. How far did they sink in? You know, if we have a big heavy ship, is it going to sink in 10 meters or something? And so it was pretty certain that it was firm enough to land on. And, of course, it was.

40:59But the upper layers are an important part of the Moon. There's a wonderful outfit in Bern, Switzerland, the capital of Switzerland, and the International Space Science Institute. We call it ECISSI, and being Swiss, they like to bring together people from different countries. So that's one of the places where I got to meet a lot of the Russians and people, Spain and France.

41:31And they formed these teams to look at things like that. I think that kind of work is going to help to clarify what we think. There was, in fact, I was invited to a team that was looking at the very early layers. But they were petrologists, basically. They were looking at the minerals. I was invited. Unfortunately, I came down with some illnesses, and I decided I better not make that trip.

42:05Much as I loved going to ECISSI. But I wrote them a little small paper about these ideas of this. You know, look, you're looking at the minerals, but you want to be aware of whether they're all ground up and mixed together. And so I wrote about that. And the funny thing was the German guy that was putting this together, Gerhard, no, not Gerhard, but Neumann was his last name.

42:41He didn't think that was very relevant when I first sent it to him. But I think they kind of changed their mind. And then there was another little irony in this, that he was trying to get a book organized of papers from the people who had gone to the meeting. And the only paper he had was the one I sent it. Nobody else had gotten around to writing their paper. So he sent that paper in, and that paper apparently convinced the publisher that, yes, this will be a nice book.

43:12So even if he wasn't interested in the science, it at least got the book under wise. That is amazing.

Future discoveries and public attitudes toward science

43:21And as we close out this session, you have been doing planetary science professionally from its foundations to you should be seeing humans returning to the moon. What are the things you still want to see and you still want to work on solving? Well, I'd like to get this. I think the one big one in my career is this issue of the history of impacts on planets and is it, was there a sudden burst at 3.9 or not?

43:57And so that's what I keep watching. There are several satellites that have conditions where there might be life. There's water under the surface of a lot of those icy satellites. And, of course, Mars. So that's, I think, the next big thing, which is going to be fundamental for human evolution. I mean, there are a lot of people who still believe there was one creation event and all the rest of this is all science that's no good.

44:34And we have that quite strongly in our country. I wrote a paper about, well, there was an international study of opinions, people going around and asking opinions. And they had a very simple sentence that didn't have the word evolution in it, but it was something like humans are related to some animal species or something like that. And there were 32 countries invited, and the United States was the next to the bottom in terms of few people being willing to accept that.

45:16In the northern European countries, that's where it was 80%, 95% people said it's fine. We were at 32% at the bottom. So in our country, you know, we have some issues about how the science is being received and worked into our daily beliefs. Hopefully, you will get to see that change as we return to the moon and get more and more spacecraft on the surface of Mars and figure out, with bigger laboratories in Percy and Curiosity, just what all those organics are related to.

46:01And we're going to have these landing laboratories on some of those satellites, too, in the next generation. Yep, Europa Clipper is on the way. It's not going to land, but it has the capacity to fly over and take samples that are sent airward. And then Dragonfly going to Titan is another one to keep an eye on. It isn't launched yet, but it is nearing completion. It's an amazing time. And I am so grateful to get to work with someone who really had such an influence on my life when I was a little kid.

46:41And I continue. I make space art, too. It's just rounder.

46:50So, yeah, you influenced me in a lot of different ways. And it's really a pleasure to get to share an institute with you and get to share this hour with you. Thank you, Bill, for such a wonderful conversation. And wonderful to be here. Thanks. It's been excellent. So, wherever you are in the world, everyone, have a fabulous morning, evening, and afternoon. And somewhere, somewhen, we will see you on the other side. Bye-bye, everyone. Bye-bye, everyone.

47:49Bye-bye, everyone.

48:19We are here thanks to the generous contributions of people like you. The best way you can support us is through patreon.com slash CosmoQuestX. Patreon benefits include exclusive access to ad-free podcasts, full-length guest interviews, weekly video chats with our production team, and other bonus content. Like us? Please share us. You never know whose life you can change by adding a little bit of science. You are listening to the 365 Days of Astronomy podcast.

48:53The 365 Days of Astronomy podcast is produced by the Planetary Science Institute. Audio post-production is by me, Richard Drumm. Project management is by Aviva Yamani. And hosting is donated by LibSyn.com. This content is released under a Creative Commons attribution, non-commercial 4.0 international license.

49:31Please share what you love, but don't sell what's free. This show is made possible thanks to the generous donations of people like you. Please consider supporting our show on patreon.com forward slash CosmoQuestX and get access to bonus content. Without your passion and contribution, we won't be able to share the stories and inspire the worlds. We invite you to join our community of storytellers and share your voice with listeners worldwide. As we wrap up today's episode, we're looking forward to unraveling more stories from the universe.

50:06With every new discovery from ground-based and space-based observatories and each milestone in space exploration, we come closer to understanding the cosmos and our place within it. Until next time, let the stars guide your curiosity.