256 | Kelly and Zach Weinersmith on Building Cities on the Moon and Mars

0:00:00.0 Sean Carroll: Hello everyone and welcome to the Mindscape Podcast. I'm your host, Sean Carroll. Longtime listeners will probably have figured out that one of the things I try to do here on Mindscape is to bring the world's experts to talk about the topic that we're gonna talk about in that episode. So, in other words, less of an emphasis on pundits or general purpose writers, or dilettantes or other podcasters, things like that. Not that there's anything wrong with that, I'm a podcaster, kind of a dilettante myself, but when I get into a topic, I wanted to get into it with the people who have really spent a lot of time becoming professionals researching this kind of thing. Today's podcast is an exception to that, but it is the best possible exception. I have zero qualms about this one. Very, very happy that it worked out.

0:00:48.2 SC: Kelly and Zach Weinersmith are a wife and husband team. And Zach, of course, will be well known to many of you. He is a web comic artist and writer. He's the artist for Saturday Morning Breakfast Cereal, SMBC, the very well-known web comic right up there with xkcd in terms of nerd credibility on the web. So I'm happy to have had both of those two artists now on this show. And Kelly is actually a PhD ecologist and adjunct faculty at Rice University. But we are not gonna be talking for the most part about either ecology or cartooning. I should also mention, to be fair, that Zach and Kelly have written a previous book that was a science book, and Zach is the author of other things like a kids' book version of Beowulf called Bea Wolf, that I can recommend very, very highly.

0:01:39.1 SC: But the topic today is space settlement. The idea of taking human beings, flying them to a space station or the moon or Mars or wherever, and living there as a sustainable society for generations at a time. Is this possible, how would it happen, what are the obstacles, and so forth. And what I love about Kelly and Zach is they just dive into it. They're super smart people who take their job seriously. They want to explain things in a way that everybody can understand, but they don't come in with an agenda. So they're rightfully proud of the ginormous number of footnotes in the book that they have, just came out, called A City on Mars: Can we settle space, should we settle space, and have we really thought this through? They've done a lot of research and because they're not in the field, they can give a somewhat balanced view of an area that often doesn't have enough balance. Because the people who devote their lives to the exploration and settlement of space are unsurprisingly kind of on one side. They think it's a great thing, right? And so Kelly and Zach also think it would be a great thing, but they're very, very clear-eyed about what the challenges are. And the challenges are quite large.

0:02:54.6 SC: So this is a fun podcast, it's super educational, but I also think it's super fair. It gives a perspective on this that we really should keep in mind. Because I think a lot of us, including myself, would like to see humankind extend itself to other environments. But if we're gonna do that successfully, we gotta know what the challenges really are. This is the podcast to come to if you wanna know what those challenges are. So let's go.

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0:03:37.9 SC: Kelly and Zach Weinersmith, welcome to the Mindscape podcast.

0:03:41.5 Kelly Weinersmith: Thanks for having us.

0:03:41.7 Zach Weinersmith: Glad to be here.

0:03:42.5 SC: So I'm gonna ask you a question. This is probably a little outta left field, not the question you usually get or have ever gotten before, but have people had sex in space? Is that possible to do?

0:03:52.2 ZW: This is a...

0:03:54.3 SC: Would it be any fun?

0:03:54.4 ZW: We have different views.

0:03:56.1 KW: We do go... Yes, we do.

0:04:00.9 ZW: We do. Well, so let us be clear that this is a probabilistic question. There is no certainty. So the question is, what value do you assign to the likelihood that it has happened? And I hit somewhere like one to 5% chance that it's happened.

0:04:13.8 KW: And I feel like if you've ever met a human, you... [laughter] Yeah. You know that humans are gonna find a way to have sex in space. And so there's no... People will tell you that, "oh yeah, we know for sure it happened." And every time we searched for a story where it was like, "oh, for sure happened", we were not able to confirm that it for sure happened. But there has been a married couple in space, and Zach points out that they were in the shuttle and it's tiny, and probably you wouldn't wanna have sex with your colleagues and you're all very professional and your careers are on the line. And I still don't think that would stop me. But I think that would stop you, and so maybe that would stop us.

0:04:54.9 ZW: Maybe, yeah. It takes two people to...

0:04:57.5 KW: That's right. You would be deterred. But...

0:05:00.6 ZW: Listen, listen.

0:05:00.7 KW: Go on.

0:05:00.7 ZW: My wife has a dirty mind. And listen, here's the thing. So you... She's using what I think of as the stoichiometric approach, which is you take like tendency towards sex and you multiply it by hours in space and you arrive at a probability. Which is an incorrect approach because you have to look at the actual facts. So consider that like up until the early 80s, it was all dudes in space. And I understand that that doesn't... I mean, it depends on what definition of sex we wanna use. But these are homophobic societies, not to make this too serious. So the odds that like careerist astronauts are gonna risk it all for a little boy and boy action in the the space shower seems dicey. I would say also... So I think one more area where Kelly and I probably agree is the... If it happened, it was almost certainly in one of the late Russian space stations. Would you agree with that?

0:05:56.0 KW: Sure.

0:05:56.4 ZW: And the reason I think we would agree with that is one, they were less monitored. So now there's perpetual monitoring just 'cause you can constantly send signal, whereas there would've been gap back then. So one, there was a little... You know, it only takes about a minute and a half to have a good time.

[laughter]

0:06:14.4 KW: A great time takes a minute longer, right?

0:06:14.7 ZW: Yeah, a great time is a minute 45.

0:06:16.9 KW: There you go.

0:06:17.3 ZW: But no, so if it happened and so like the ISS, it would be very hard to get away with. You basically have to have a conspiracy between international... Where would you do it? She's shaking her head at me.

0:06:28.2 KW: I don't know, it could be in the rest for like... Or it could be in of their cubbies... No, wait. They've got their little cubbies that they sleep in. Sean, I told you we don't give short answers.

0:06:36.6 ZW: It fit one person in the cubbies.

0:06:37.1 SC: I understand.

0:06:37.1 ZW: You're gonna get like carbon narcosis as you exhale into the coffin-sized cubbyhole. So anyway, so if we agree though, it almost certainly had to happen on a Russian space station. Almost no women went to those stations.

0:06:50.3 KW: That's not true. Shuttle-Mir, there were plenty of Shuttle people there, short at... We disagree.

0:06:56.4 ZW: There's no way Shannon Lucid... Shannon Lucid was the only long-term woman staying on Shuttle-Mir...

0:07:00.5 KW: You don't have to be long-term. You only have to be on there for a minute and a half.

0:07:03.1 ZW: Okay, but Shannon Lucid was like a librarian from Oklahoma in between being an astronaut. I just don't... She was excited about...

0:07:11.3 SC: I have another human nature data point that is relevant but is actually against Kelly's argument because...

0:07:17.2 KW: Oh, then I'm not sure I wanna hear it.

0:07:18.7 SC: If I were part of the first set of people to ever have sex in space, once I had been retired from being an astronaut, you think I wouldn't let people know about this? Like, this is a historic thing.

0:07:32.3 ZW: That's right. That's right.

0:07:33.4 SC: Someone's gonna be first.

0:07:34.0 KW: But that is both a good point and a good insight into human behavior.

0:07:39.9 ZW: Let me, I hate to side with my own wife on this. But I would say, so for example, Lynn Sherr is a biographer of Sally Ride. Very good friend of many of the women astronauts in the program going back to the 70s. And she said she knew the first woman who menstruated in space, who has to my knowledge, still not been identified. So like...

0:08:00.1 SC: That's a little bit less of a thing to be known for.

0:08:03.1 ZW: It is less thrilling, but it is like, astronauts keep secrets about certain things. So I think there might be like you can't use the standard anti-conspiracy theory argument that humans blab, 'cause this is a very special set of humans who are extremely career oriented.

0:08:18.3 SC: Fair enough, fair enough. Okay. Well, I wanted to get that, you know, probably the only time you'll get to talk about this. 'Cause this is not very interesting...

0:08:24.3 ZW: It's super not a hell of a detail, yeah.

0:08:25.7 SC: To most people. But I think that most of what you're concerned about, in your new book, which we will note is called A City on Mars: Can we settle space, should We settle Space, and have we really thought this through? Slightly, Mr Peanut Butter-esque title there. And it is mostly about gravity, right? You're mostly thinking about literally being on a planet. You're talking about settling things in space. We're not gonna, for the rest of the hour, talk mostly about Zero-G flights. Is that right?

0:08:54.8 KW: That's right, yeah. The three places that we focus on the most are the moon, Mars and rotating space stations. And out of all of those, we think that Mars is probably the most likely.

0:09:05.8 ZW: Yeah.

0:09:05.8 SC: Well, the moon is the closest, I mean, at least until we build big space station. So how would it work? What is the scenario that we are contemplating here? We're talking about not just flying human beings to Mars, but literally building a settlement and staying there, right? What is the situation we're both imagining and then critiquing?

0:09:27.6 ZW: Yeah, sure, sure, sure. So the... You can get a little lost in the nomenclature. There have been attempts to disambiguate like what's an outpost and what's a settlement and stuff. But generally speaking, we would say settlement is somewhere where people can have kids. And so you're probably at least talking like a few thousand people. The scenario I would add that a lot of space expansionist advocate types are concerned with, is in particular a settlement that has the set of qualities that would allow for permanence in the sense of Earth could explode or just lose contact and you could carry on.

0:10:00.3 SC: Self-sustained, yeah.

0:10:01.4 ZW: Self-sustaining, yeah. Permanently self-sustaining, which is like... The thing about permanent self-sustaining is it's like, you have to think in terms of generations. So that's a whole can of worms, but it's a huge, huge thing to be permanently self-sustaining. So I'd like to think we're critiquing it at several levels. But we're... I think a better way to think about it than in terms of population stuff is to think about the components that you need to succeed at to pull this off. And so most basically you have to have a kind of survival bubble that can provide all the consumables you need either locally or by shipping them at a great expense. Outside of that, the next big thing is usually shielding, because most places in space are going to be assaulted by radiation. Earth has this nice thing called a magnetosphere. Mars has very weak magnetism. The moon, I believe has none at all. And so you're gonna have to provide against that.

0:11:01.5 ZW: And then they... You get to more biosocial science stuff. You need to have a local ecosystem. Unless you're willing to truck in enormous amounts of consumables, you have to be able to grow plants, because plants provide both oxygen and food. And you have to have medical services and to be able to provide reproduction, which is... A huge thing for us is that this is basically undeveloped science, human reproduction off-world. There's more I could get into, but yeah, these are...

0:11:28.4 SC: We will, we will. But I guess what I wanted to get at was, let's say that instead of writing a book and telling the truth, you were working for NASA or for some equivalent agency or private corporation and wanted to set out the roadmap for how it would work. What are the steps that are involved in creating human settlement, let's say on Mars, although we'll talk about the other options.

0:11:54.6 KW: Well, so I'd say first you want to... Sorry. I'd say first you want to understand how the human body responds to space before you send people out there without a plan to bring them back. So one problem that we have is that most of our data have come from places like the International Space Station, where you have a station orbiting Earth in free fall. So we know that no gravity is bad for our bones and our muscles, and that fluid shifts and impacts vision. And we know that that's bad, especially over the long term. But we actually don't know how bad it gets over the long term because the longest stay is like a year and a half. And the moon and Mars, the moon has one-sixth Earth gravity, and Mars has about 40%. Maybe that's enough to get rid of all of the bone problems and the muscle problems, but we just, we don't know right now. We don't have a lot of...

0:12:42.9 SC: Okay, you are... I'm sorry, but you are not doing a good job at being NASA and giving me the roadmap. You're instantly...

0:12:48.6 KW: Oh okay, okay, roadmap. Okay. Human health...

0:12:52.9 SC: You're instantly jumping to the problems.

0:12:53.0 KW: Oh, okay. Alright. So human health...

0:12:56.5 SC: But no, literally how we get there, what is the plan? Do we build one rocket and go first? Do we first go to Orbit and build a space station to... Like how many rockets do we need? Like what is the set of steps that must be taken to make this happen?

0:13:10.2 ZW: So let me... So there were a lot of different proposals. It might be interesting to think about the one Von Braun was proposing way back in the 50s that we deviated from in favor of the Apollo program. And his proposal, which you hate to side with an ex-Nazi, but his proposal which, setting aside cost, is way more sensible than what we ended up doing. Which was you build a very large space station, which would consist of like 80 people. And the reason you do that is 'cause now you have a manufacturing facility close to Earth that can work in Zero-G and that means that when it's time to go to the moon, you can go in style. So you can... For him that means sending geologists and all that stuff. But it also means if you wanted to set up a substantial base on the moon, which you absolutely want to do before Mars, then it would really help to have a manufacturing system. There are debates about this. In some world rockets get so cheap you just send the rockets straight to the moon. But let's just say it.

0:14:04.3 ZW: And then what you would wanna do is really build out on the moon. And the reason you wanna build out on the moon, we argue, is that you just need... It's almost less about science than something like an employee handbook. There's just a lot of stuff you don't know until you get there. And so we need kind of best practices for converting this dead horrible soil... I mean, it's not the same as Mars, but it's at least in the realm of it, converting that to an ecosystem. And we really need to learn... Like a big track of this is learning how to build an onsite ecosystem that can supply most of your consumables on an ongoing basis. Also, that's an opportunity, while we have our base on the moon, to work out the problems in reproduction which is a long way off. You'd ideally wanna scale through this, this is what we're doing running the settlement agency. You'd want to do this ethically, which means starting with simple animal systems and working your way up until you could be comfortable with humans.

0:14:57.5 ZW: And at some point if this works out, I note it would be very expensive. There might be an angle on tourism to fund some of it. At some point you've mastered how to get humans to live in this horrible place where everything outside of your protection bubble is doom. And hopefully in the meantime you have developed massive rocket technology because it's gonna be much harder to get to Mars. Mars is six months inbound. The moon is two days inbound. And so there're gonna be new things to do. But I think plausibly, once you've mastered how to live like a thousand people on the moon for some period of time, like if you have the equivalent of our Antarctic base at the South Pole on the moon, you're probably ready to take a stab at Mars. I think that would be our roadmap.

0:15:41.5 ZW: The other big thread of that is that the legal aspects are a little funky. But if you're just talking about research bases, even if they're quite substantial, that's all on the up and up. As long as you're not claiming to own anything under the research stations.

0:15:55.4 SC: Okay. But that's very, very useful. So you are telling me that my goal is not to build some giant rockets and fire them at Mars, but rather to go by steps to... Maybe explain a little bit more about why the space station is useful as well as going to the moon, and then if I'm gonna go to the space station anyway, are do we sure we need the moon? Isn't the space station even harder? Could we have a thousand person space station as our trial run?

0:16:24.8 ZW: Yeah, so I think at least in the old Von Braun model, he was talking about like an 80-person space station. And I think the basic idea is that, and this is... I think people have been talking about for a long time and has yet to be proven, there's certain things that are easier to do in zero-G, plausibly building a giganto spacecraft. Is there historically? We, meaning like everybody doing space, has been opposed to rendezvous, I guess. And I talked to an aerospace guy and he was basically like, rendezvous is really hard. And if you know the history of the Gemini program, you know a lot of problems came from trying to dock Gemini with a Agena, which was this rocket system for space. And so part of the weird thing about Apollo is there is no rendezvous. You just launch a skyscraper and little pieces of it break off until finally a teeny weeny dinghy goes to the moon, right? That's no good for a settlement.

0:17:14.7 ZW: But in fairness to the people who are excited about new developments, scaling really would help a lot. Like getting a lot of starships rolling. Starship for people who don't know is this rocket with about the capacity of the old Saturn V. It's this giant incredibly ridiculously huge vehicle SpaceX is working on, and more importantly, trying to make reusable. So the price of launching stuff to space would be quite low. So for obvious reasons, I think that kind of scaling really makes a difference. Possibly it even obviates the need for any kind of space station because you can just, you get so good at throwing mass out of Earth. That's totally plausible. More spacey arguments that were popular in the 70s were maybe you build a mass driver on the moon eventually using all of that capacity so you can just use pure electricity to slam stuff into space. But that's getting a little more speculative than we like to get.

0:18:09.1 SC: But maybe there's a little bit of a lesson, which is that gravity, as annoying as it is, is actually helpful in some ways. In fact, maybe it's just not that easy to do manufacturing of giant things like spacecraft in orbit because things tend to float away. And it's hard to match them up because you don't have a level. And I don't know, but I could imagine that it turns out to just be easier to go to the moon and build your Mars rocket there.

0:18:39.0 KW: Yeah, no, totally possible and plausible. And Zach and I only researched the most important topics. And so we can tell you that almost every single vehicle that has been in like Zero-G has had problems with escape of waste and faeces floating through the air. On the shuttle, they were called brown trout. And you are... You don't want your brown... You want your brown trout going downstream into the toilet.

0:19:03.5 ZW: Gravity is nice. Yeah.

0:19:04.5 KW: And so, yeah, gravity's nice for a lot of reasons, and it helps with waste as well.

0:19:07.7 ZW: Yeah, and that's part of why one of the arguments for these big rotating space stations, which we're fairly skeptical of, but one of the arguments is by going toward the center, you can select your gravity regime. Which the argument is that'd be good for manufacturing. That seems like a whole lot of work to get this benefit. So it hasn't been proven, certainly. But...

0:19:23.0 SC: Okay. So in our hypothetical roadmap, we're going to the moon first. We're making sure we can live there for a while, working out some of the kinks, and then we'll eventually go to Mars. I mean, why not just stay on the moon? Isn't the moon closer and nicer? What's so great about Mars?

0:19:40.5 KW: So the moon is closer and nicer, but it lacks a lot of stuff you're gonna need for a self-sustaining society. So the water that it has, there's small quantities of it on the poles in these hard-to-get places, whereas Mars has a lot more water just about everywhere. There's still more of it at the poles, but almost anywhere you are, you can find water. Plus, we are carbon-based life forms and the moon has very little carbon. In fact, I think most of it is in the fecal and vomit bags that were left behind by the Apollo astronauts... No, maybe not most...

0:20:09.6 ZW: Most of it. Yeah.

0:20:11.3 KW: A fair bit of it.

0:20:12.8 ZW: Concentrated carbon, yeah.

0:20:14.9 KW: Concentrated sources. So the moon doesn't have a lot of carbon. We're gonna need that to make humans, to grow plants. And so we're gonna have to truck that in. But if you go to Mars, the atmosphere is made out of carbon dioxide, and you can break that up. And there's just a lot of things that you can do on Mars that would be hard to do on the moon. So in terms of self-sustaining life, Mars has a lot going for it that the moon doesn't.

0:20:39.3 SC: As far as our roadmap is concerned, are we gonna want to eventually terraform Mars that the atmosphere is breathable? Or is that just crazy talk?

0:20:46.8 KW: So I am an ecologist, and I would argue that we maybe don't understand all of this stuff well enough to be throwing nuclear bombs at the pole of Mars and hoping that you get just the right temperature and just the right thickness of atmosphere. So we, to be honest in the book, don't get too much into terraforming. We are talking about more of like the early stage, how do you start a society, right? What's legal when you get there? What kind of health problems would you have? But I don't know. I mean, it would be nice if Mars were warmer but but I'm not sure we're gonna be able to do that.

0:21:20.0 ZW: And, one thing I would add to that is like, and this never comes up in terraforming conversations, but is like whatever plan you wanna use, whether you're like hurling comets and asteroids at the Martian poles, or you're like, detonating 80 trillion fusion bombs, what geopolitical legal framework countenance is this? Like, who's doing it? Right? Like, suppose tomorrow, Vladimir Putin says, I wanna throw... I mean, he can't, but let's say he surprised us all and this whole time they've been building fusion powered space vehicles, and he is like, we are about to hurl the comets. Don't worry, they won't hit Earth. They're going to, lots of clearance and they'll hit Mars on target and terraform it. And we're gonna do that 'cause it's great. Like we don't even know how to think about that. That's obviously extraordinarily dangerous. And in terms of like international law, it's very ambiguous whether that's allowed. I would say it seems to me like it probably is, but there are environmental concerns. So...

0:22:14.9 KW: You'd have to contact another country with I'm concerned about your environmental impact.

0:22:20.6 ZW: Right. Yeah. So it is, in some sense it would be legal, but like I think obviously terrifying and I don't know, like that seems to me like not a like quibble.

0:22:29.6 KW: And it would totally tank the space settlements. No one in the next 20, 30 generations would be able to do it, especially if you hit it with nuclear weapons.

0:22:37.4 ZW: Yeah. And that's the other thing, by the way. So I would say like if we're talking about terraforming, then you're talking now on the millennium scale, not on...

0:22:45.9 SC: Okay. And also we're not even that great at fine-tuning the temperature of the atmosphere here on Earth.

0:22:51.6 ZW: Yeah.

0:22:52.8 KW: Amen.

0:22:55.5 SC: So you, but you did mention comets, so let me very briefly get that on the table. So there's an idea that we can use comets as raw materials, right? Like comets have water and ice and volatiles, and maybe mining them or bringing them to our space settlements might be a very long-term future goal.

0:23:15.3 ZW: Sure. Yeah, the only thing I would say about that is you have to be really careful. We didn't put this in the book, but we started calling it something like the elemental perspective, which is a very sort of engineer physicist way to look at how to survive, which is like, well, do you have enough carbon and hydrogen? Therefore you can make life, you have to be really careful.

0:23:31.5 SC: What else do you need?

0:23:32.9 ZW: What else do you need? Yeah, well you need some sulfur and phosphorus.

0:23:37.3 KW: Nitrogen, yeah.

0:23:39.7 ZW: But yeah. So a really good example of this, and this is a gripe, but we're allowed to go in depth on the show.

0:23:41.4 SC: Yeah.

0:23:43.7 ZW: So you will hear over and over, Harrison Schmitt, the only senator/geologist/astronaut, pushes this, the idea that we'll go to the moon and get helium-3, a rare isotope of helium, that is indeed quite valuable. And the idea usually is that we will use it in a fusion drive, and it's especially cool fusion drive. I believe the usual reaction is with deuterium, and it's Aneutronic. So you won't even have to like, fix the walls. They didn't get radiated in your tokamak or whatever. So, yay. The problem with this idea is that one, obviously we don't have the fusion device, and it actually uses like an exotic reaction when we can't even do the easier one yet, which seems to matter. Two, I think the Aneutronic business is overstated. I kind of feel like if you've got fusion working with good old Deuterium-tritium, like the job is done, go home.

0:24:33.4 ZW: But I think more importantly, there's not that much, it's a higher concentration than you find on Earth, but in order to get a reasonable quantity, you're like strip mining a huge amount of the surface of the moon, which like, separate from whether... How we feel about that. Like try to imagine building equipment to work in this no air, low gravity, two weeks night, two weeks day, et cetera, environment. Like the idea that you're going to make money doing this is crazy. Michelle Van Pelt, who's a scientist at ESA, and this is five years ago, so maybe the equation has slightly changed, but he said and it's almost verbatim, I think, if there were bars of gold sitting on the moon, it would not be worth it to go get them. Now, if you change the economics, if you say, well, it's so valuable to have water on Mars, then the economics change. But I think that tells you something about life on Mars.

0:25:21.1 ZW: Which is, it's not pleasant. So I think the comets for water thing is a cool sci-fi thing. I'm quite skeptical that that'd be a good way to... I mean, the one thing I would add with all these conversations is space geeks. You get into arguments with them and they're like, well, I'm talking about the next 10,000 years. You're like, okay, okay. I think the prediction horizon right now is like 50 years. So if you wanna talk about 10,000 years, that's fine, but...

0:25:41.5 SC: Can't argue, right?

0:25:42.0 ZW: Yeah. Right.

0:25:43.2 SC: So, if I understand then the attraction to Mars versus the moon, it has more water, it has more carbon dioxide, et cetera. But it's not that we're literally going to be farming on the surface of Mars, it's just that we have the raw materials out there to mine or collect and bring to our underground or enclosed settlements.

0:26:06.0 KW: Yeah. And it's still gonna be awful. That soil that you might want to plant your plants in, it's about 1% perchlorates, which is a chemical that binds to the hormones made by your thyroid, and those hormones regulate things like blood pressure, heart rate, stuff like that. So you're gonna want to remove that because studies have shown that it does get picked up by plants when you grow plants in them. And so first, you're gonna have to pull the perchlorates out of the soil before you can even start your farm. And there's all kinds of the dust storms, those are gonna be miserable and they're gonna make solar panels difficult. Like yes, it has more of what we need, but it's still gonna suck.

0:26:46.6 SC: Right. That's fine. Okay, good. Good. Well, at least now, I know the motivation such as it is for continuing on beyond the moon to Mars.

0:26:54.3 ZW: Sure.

0:26:54.9 SC: But you mentioned if the goal is sustainability, that does include human beings reproducing. So someone's gonna have to sex in space at some point. I don't know when, but... And they're gonna give birth.

0:27:07.7 KW: And probably they'll talk about it.

0:27:09.3 SC: Yeah, they will talk about it. There might be videos, I don't know, but then they will give birth and that's a whole nother can of worms as it were. What do we know about both giving birth or for that matter being pregnant, but also being a baby on the moon or on Mars?

0:27:27.3 KW: We know... Can I do this one?

0:27:29.2 ZW: Yeah, please.

0:27:31.5 KW: We know almost nothing. So we very rarely send up rodents with the goal of understanding sex or reproduction or development. And when we do, they're sent up for a small window of the gestational period. So they're like shot up at incredible Gs, they're pushed back against their cages, they're up in space for like a week floating around, and then they fall back down to Earth at incredible Gs and then they look to see what happens. And maybe not surprisingly, a lot of stuff seems to go wrong, right? That's probably very stressful. We've recently started making these like wheels that spin and create artificial gravity that are on the International Space Station.

0:28:10.9 ZW: Little tiny ones for rodents.

0:28:12.9 KW: Little tiny ones for rodents. And we've started to train astronauts to euthanize the rats and process them in space, so you don't get that final trip back down. That's very stressful. But that's pretty much where we are. We haven't... We don't even have rodents that have had sex, had babies, those babies survived, and they went on to have babies. None of that has happened in space so far. And so we really don't understand, one, how gravity impacts reproduction. So as we mentioned, the International Space Station has effectively no gravity, whereas these other places have some gravity, and maybe that's going to be enough, but maybe not. We don't really know. And then also the International Space Station is protected by Earth's magnetosphere. So those rodents are not exposed to space radiation that you'll get on the moon or on Mars. And maybe you can shield with like a thick layer of regolith and protect everyone from that radiation. But we really don't understand the impacts of that stuff yet and how well it's all gonna work out.

0:29:18.0 KW: So we would say that there's huge question marks about whether or not this is gonna go well. And to us, that seems unethical. And usually this is something that the space community seems to just sort of not deal with directly, but when they do deal with it directly, it's horrifying. Like, we found quotes of people saying like, look, life is gonna be really hard on Mars initially, and everybody's gonna need to be pulling their weight. And so we might have to encourage people to get abortions if it looks like their kids are not gonna be able to contribute. And but what does that mean for things... Disabilities that come on at three years of age or something? Are we gonna be pushing toddlers out of airlocks? And it just... Anyway, this all gets very uncomfortable the more you think about it. So that's part of why we wanna see research stations on the moon. We'd like to at least know that it works okay at 1/6-G and that we can do this without too many calamities when people can still get sent home in a couple days as opposed to being stranded on Mars.

0:30:08.3 SC: And the space radiation point makes me I should have gone back to our roadmap and pointed out, I guess it won't be like glass domes on the moon or Mars. We will literally be either building giant shelters with a lot of shielding or just going underground.

0:30:22.6 ZW: Yeah, I think that's right. So, there is some world maybe in which you have plants in a martian glass dome, though understand you have almost no pressure outside and at least some atmosphere inside. So already the problem is extraordinarily difficult from a materials perspective. But at least in principle, you could do that because the plants might survive. Okay, you could let in carbon dioxide from the atmosphere, but yeah, humans strolling around is going to be a problem. And it's a problem that actually has weird consequences. So I don't remember if we get into this, but as an example, one question is what happens to gametes in human bodies? You know, those are precious gametes if you want to have generations and women start life with their full gamete load, whereas men produce their whole lives. And so like, would you have gender-based rules for who has to stay underground? That doesn't seem great. But, or age-based...

0:31:19.2 SC: It's a harsh environment.

0:31:20.8 ZW: Yeah, no, that's right. Yeah. So, that's the thing though. So you can always say like, well, it's just gonna be different 'cause it's a settler lifestyle, but it's like, do we really wanna create this horrible lifestyle?

0:31:30.3 KW: And if you can anticipate ahead of time that it's gonna be horrible, then don't send people there.

0:31:35.2 SC: Well, and also, unless you literally are worried about the Earth coming to an end somehow, what is the benefit of building an underground city on the moon or Mars rather than underground city on Earth, which doesn't seem to be very popular as a prospect.

0:31:49.0 ZW: Absolutely. Yeah. Yeah. Well, so one example we'd like to go to is, it would be far easier to build a city on the bottom of the sea, right? And so if you have a self-sustaining bottom of the ocean city, it's really hard to imagine what could happen to Earth that would eliminate that city. We actually as an intellectual exercise ask yourself what you could do to Earth to make it as bad as Mars. Right? To just... Like the only thing I could come up with was you'd have to slam it with a lot of very large asteroids. You'd basically have to superheat the surface to get anything like Mars. Earth is good.

0:32:20.7 KW: But I'll say like...

0:32:23.9 SC: Earth is good.

0:32:24.0 KW: Earth is really good. But I do still feel like it's a beautiful idea to have humans on Mars. I like the idea of it happening at some point, even if we're living underground like ants, it still feels like...

0:32:35.5 ZW: It's still awesome.

0:32:36.1 KW: It still seems awesome to me, but I just think we should do it in a way that has fewer ethical...

0:32:44.3 ZW: Totally.

0:32:45.8 SC: Ethical issues.

0:32:45.9 SC: Well, and also let's admit to the force of the argument for backing up the biosphere. Right? Maybe there would be a terrible thing that happens on Earth and it is the only place we are now. I absolutely see the impact of an argument that says if literally the existence of life is in danger, we should go to great lengths to prevent that disaster from happening.

0:33:10.8 ZW: Yeah. Yeah. I would say that I... And we basically agree with that over the long term. The two points of pushback on that are one that you have to say like, because that's essentially an argument to spend a bunch of money, whether or not there's an ROI on it, right? It's an ought argument. We ought to do this outside of economics. So the problem is one, almost certainly a dollar is better spent on something else reducing catastrophic risk, at least in the next century. Yeah. So one, if you sort of list as Toby Ord does, the set of calamities, a bunch are gonna be higher than annihilation of the species on Earth that could be salvaged by a Mars base. The other pushback, which is longer term is the big question, if you're just talking about existential risk, I do think it's a kind of open question whether settling Mars increases or decreases over the long term existential risk.

0:33:57.8 ZW: Because we only talk about this briefly, it's about as speculative as we want to get, but interplanetary warfare has like nightmare potential. Because like one of the reasons... I mean, this is a whole debate, why don't we use gas weapons typically on each other? And they're psychological reasons of course, but one reason is that gas doesn't know which way to go. And the same with bio warfare. There's some things you don't do 'cause it might come back at you. Well, if you throw these things down a gravity well, the risk is lower. Or at least, it would be very hard to get the disease back to you. You know, there's six months between places. So, it is just speculative, but it is worth in your equation adding that there is at least some risk of the existential risk increasing as a result of going multi-planetary in the same solar system.

0:34:42.1 KW: When I... I think the existential risk increases in the near term as well. So for example, if we're starting on the moon, which we probably will, there's very, very small surface area that's the best spots on the moon. And those are the spots where you've got water and where you've got the rims and you can get more... Your solar panels can get light for more of the time. So it's very clear where we're going to be scrambling for when we start going to the moon. And we have this international law regime that's sort of unclear about what you're able to do when you get there. And right now, we've got this new emerging space race between China and the US for these great spots on the moon. And whereas the space race with the Soviet Union was more who can just touch down first, and that's it. Now with China and the US, we're talking about places where you're gonna set up for forever and people starting lunar economies. And it sounds more like a scramble for land and between nuclear wielding superpowers who are getting along less and less well as time goes on. So that's concerning.

0:35:39.9 SC: I liked the TV show Space Force. I know a lot of people didn't, but I thought it was hilarious with Steve Carell. Sorry that that one got canceled, but it was about exactly those issues. So we should take them seriously, I think. But okay, so basically you're saying that in our... The irony would be that in trying to eliminate some existential risks, we've created a giant new existential risk and that is something we should worry about.

0:36:04.4 KW: And if you're interested in more on that, you should read Daniel Deudney's Dark Skies. 'Cause that whole book is about how going to space is, could be really bad for Earth.

0:36:14.8 ZW: He's an international relations guy, so he is very explicitly concerned with that aspect of the question.

0:36:16.2 SC: Okay. Well, moving on to slightly happier topics. I'm a little bit surprised that of the many science experiments that have been done on the space station, we haven't done multi-generational animal reproduction. I mean, if we are serious, like you say about living in space, we gotta do that. Are there plans to do that? Are there hopes?

0:36:40.8 KW: So I would say that there's a couple problems. So one, NASA is very squeamish about sex. They don't want...

0:36:46.8 SC: Even rat sex.

0:36:50.0 KW: Even rat sex. No. It's like, it's hard to get access to the NASA researchers who study sex because what they say to journalists is very tightly controlled.

0:36:58.4 SC: Got it.

0:37:00.6 KW: And so NASA doesn't wanna get in trouble with the taxpayers. They don't wanna talk about alcohol in space. They don't wanna talk about sex in space. And also I would argue that the International Space Station, as far as I know, the stated goal of the Space Station wasn't as a stepping stone to settlements. And so if that's not one of the explicit goals, then there's plenty of short-term things you want to understand. Like the astronauts who are up there for two years, how is that impacting their body? And can we keep doing this or is it not safe for them? And so, go ahead.

0:37:28.0 ZW: Yeah, to add to that, so one way to think about NASA is as this agency that started with the Apollo program, and it's all Apollo, it's all beating the Soviets, it's a political act. And then that's done. And then the question is what now? There's a historian named John Logsdon, he's one of the preeminent historians, he referred to as what happened afterward as a forty-year identity crisis. I think he might say fifty years now. And so if NASA was set up as the settle-at-the-moon agency, then you would expect that on the space stations, we would have a systematic series of experiments, but we don't. It's one of the frustrating things when you're trying to answer a question about something like space psychology, is what you just have is forty years of grab bag. You have lots of experiments done by lots of people in different settings without a unified we-need-to-know-this-for-sure aspect.

0:38:05.0 ZW: And so we talk about this at the very end of the book, if you're making the like Zach and Kelly are in charge of the NASA settle space agency or whatever, one of the priority things would be we would want to orient around a systemic... Systematic program to just answer questions. Frustratingly, with a lot of space stuff that doesn't have an objective measure like loss of bone density or something, it's really hard to get answers in part because of that lack of systematicity. And so when you look at... We tried to find every single experiment we could relate to like gametes or reproduction or reproductive health or hormones, and it's just, there's just a lot of experiments and you are there to make sense of them. There's not a kind of textbook approach. So that is why we don't have that kind of thing. NASA is not dedicated to settlement or anything like that.

0:39:00.5 SC: And as you... You do make a pretty good case in the book that when it comes to psychology, you've given the actual human subjects a huge incentive to not tell the truth about their psychology. So basically nothing is reliable.

0:39:15.4 KW: No, we read stacks and stacks and stacks of astronaut and cosmonaut biographies, translating them with Google Translate. And they almost all lie about their mental and physical health. And it's the incentives, if they say, oh, you know what? I'm actually, I'm depressed. I'm having a bit of a panic attack. You don't get to go up for another flight. And so we found... And same thing, you can't say, oh, you know what? I'm having some chest pain, maybe it's a heart attack. You're not gonna go up to space. And so there were stories about one guy thought he was having a heart attack, didn't say anything. Another guy thought he had bone cancer. Was that the same guy?

0:39:49.4 ZW: This is the same guy.

0:39:49.5 KW: That was the same guy.

0:39:52.1 ZW: It was Walter Cunningham, yeah.

0:39:52.1 KW: One guy...

0:39:52.5 SC: He might be a bit of a hypochondriac.

0:39:54.6 ZW: I guess so, yeah.

0:39:57.0 KW: Mike Mullane removed papers from his medical records because somebody was stupid enough to let him travel with them. So he just ripped them out. But he said that he would have lied about a glass eye if he thought he could get away with it.

0:40:10.7 ZW: Oh, the guy who cheated on a vision test.

0:40:13.0 KW: Oh yeah, he memorized those card tests where there's a number hidden in the dots. So he memorized those...

0:40:19.8 ZW: There's another story I think it was maybe Bassett, who was an astronaut candidate who unfortunately died in an accident. But I believe he was the one who stayed up all night jumping up and down to get his height down 'cause of the height limit.

0:40:30.4 KW: Another one, or maybe it was the same one, learned to slouch just a little to get under the limit. But I think only once has this actually been a problem. There was one cosmonaut who went up who had a health problem that had started beforehand. If he had admitted it, they probably wouldn't have let him go, and he had to come back. And it was interesting 'cause one of the women cosmonauts, instead of being like, oh, poor guy, she was mad at him not because... She was mad at him because he didn't continue the lie. She's like, look, we all lie. The problem isn't that he lied. But if you lie, you have to suck it up and you finish your mission. And he messed stuff up so she didn't get to go. And so she was furious, not that he lied, but that he didn't go all the way through with it, 'cause that's what you're supposed to do.

0:41:17.4 SC: So there's some open questions about the psychology. I do wanna... Maybe we can at least speculate about the physiology in particular of a newborn baby. I'm gonna guess a baby that is born and raised on the moon will have a tough time coming back to Earth. At least that's what my science fiction readings would lead me to believe.

0:41:38.6 KW: Yes, no, I agree with... What? I think that was in The Expanse also. I agree, a baby that is developing under 1/6 or 40% gravity, they might not have bones that are strong enough to survive entry through Earth's atmosphere and then landing on Earth and walking around. And to be quite honest, we don't even know if human hips can handle childbirth and after a lifetime at some percent of Earth's gravity.

0:42:05.5 ZW: Yeah.

0:42:05.6 KW: What do you think?

0:42:05.5 ZW: I was just gonna say, you should give the number on that. So in microgravity, what was it, one or... Yeah.

0:42:10.8 KW: You lose 1.5% of aerial bone mineral...

0:42:14.9 ZW: Density.

0:42:15.7 KW: Density, which I think is a measure of osteoporosis. So 1.5% of that in your hips is lost per month.

0:42:20.8 ZW: Per month.

0:42:22.3 KW: Per month.

0:42:22.7 SC: Per month.

0:42:23.0 KW: But again, that's in complete free fall. You don't know how much better that gets when you're at 40%. Maybe that gets rid of the loss entirely, but maybe not.

0:42:31.5 ZW: And one thing I would add to that, there's a great quote I found in an interview with April Ronca, who's the person in NASA who's maybe the top babies in space. That's not her title, but you know what I mean. It's someone had asked her, and I can't remember what book this was, it was something like, hey, are we gonna have longer legs on Mars? And she said something like, I don't know. It's a very human thing to be like, there's less gravity, so longer legs. But there's all sorts of mechanisms in your body and we don't know how they're going to respond. So there's stuff that might be unpredictable, which means it might be fine as well. One of the big surprises of the early space program was that you could eat fine. That was an open question. It's kind of weird, frankly, that you can eat and it basically works. Apparently burping is dicey, but generally speaking, in zero gravity, but generally speaking, it works, which is like, I don't know, for me, it's kind of surprising. You can eat stuff and it goes to the right place and this body could evolve.

0:43:21.0 SC: Without gravity, yeah. And okay this does speak to the idea that the first time we go to Mars, we won't be coming back. Is it, I've often guessed, but maybe you're the experts here, that the first humans to visit Mars will be on a one-way trip 'cause it's just so difficult to come back. And then maybe if you have generations there, they have no choice but not to come back. I don't know.

0:43:48.9 KW: If it were up to me, the first people to go to Mars would be like six crew on a NASA mission and they come back. I think there's a lot that we need to learn and it would be nice to go there, stay for a little while and come back. I don't think the first time we send them there, we should be leaving them there.

0:44:04.6 ZW: Yeah. I don't know, I could be wrong. I don't think there are any serious proposals to just leave them there. I think usually, there's some orbital mechanic stuff, but I think there's actually a trajectory where they would stay on Mars for just a month and then come back. It's not usually popular, 'cause what a waste. The usual trajectory is like six months inbound. And then I think something like two years later, it's six months outbound. But I think even with someone like Robert Zubrin, who's very much a daredevil when it comes to other people's safety on their Mars trip, still proposes that you send a robot system ahead to rack up methane as propellant on the way out. So no, I don't know. I would say this, there's good evidence that there would be volunteers for a one-way Mars trip. But I think at least if you're talking about sending a few people out for the very first boots on the ground, I don't know of any proposals that would just leave someone there.

[overlapping conversation]

0:44:54.0 SC: Well, this does bring us to the question of government versus private efforts in these directions. It would be cheaper to send people there one way. And if it's not the government doing it, like you said, there will be volunteers. So I'm very open to the possibility that that will be first.

0:45:12.1 KW: Okay, well, sure. However, so if Elon Musk, for example, wanted to send a bunch of people to Mars and just leave them there, according to international law, the things that happen on Mars are the responsibility of the United States. And I'm assuming that Elon Musk is launching from the US and he's from the US, so he's the US's responsibility. So the FAA should be thinking about the ethical implications of this before they allow it to happen. So there is some oversight, but with all the geopolitical power Musk seems to have right now, and it's showing with Starlink and this Ukraine stuff, I don't know, maybe he'd get away with it. But it's not like private companies can make these decisions completely on their own.

0:45:54.2 ZW: Yeah, I would also add, there's this argument we encounter a lot from space people who's like... So we talk a lot about international law and we think it matters, and there are a lot of constraints. You'll get a lot of space people who'll be like, Elon Musk and me are going to the moon and it's none of your business and you have no way to stop us 'cause we have the rockets. Which is basically just bogus. And if you want to convince yourself, ask yourself if Elon Musk has ever said anything bad about the Communist Party of China. Elon Musk has business interests on this planet. And so if he does something that actively antagonizes every country on Earth, there are going to be consequences that will make him sad.

0:46:30.1 KW: Also, if he goes... So in the Starlink's terms of service, he essentially said, when we go to Mars, we're not gonna be bound by Earth law. That straightforwardly flies in the face of international law, including treaties that have been signed by the United States. And so if he...

0:46:46.8 ZW: And China and Russia.

0:46:46.9 KW: And China and Russia, all the major space powers. This is a highly ratified document. So if he goes to Mars and is like, ha, you idiots let me come here and now we've got our own nation and I'm not listening to anybody, then it would be the FAA's responsibility to say, fine, none of your resupply ships can take off. So even after they leave, we still have some control if the US government decides to exercise it.

0:47:11.4 ZW: I guess, I'm trying to think of your exact question. I suppose I don't know what would happen if Elon Musk paid for a venture to the North Pole and it was badly planned and everyone died. What would be the consequences? And I honestly don't know. It seems like when Elon Musk does something, no matter how badly it goes, everyone thinks it's cool. So I don't know.

0:47:28.4 KW: I'm on Twitter or X. I don't agree.

0:47:30.5 ZW: Yeah, X, X. Yeah, all right, all right, all right. But so in terms of the sort of specifics, I don't know, but in terms of setting up a settlement, it would be a really bad move to antagonize Earth. And I would add one thing we talk about is people tend to talk about these things as abstractions. Like a settlement is set up by a private company, but in reality, the private company is from somewhere. And so suppose you say the "private" company is from China, that feels geopolitically very different than it being from the US. So if Elon Musk surprises us tomorrow with 10,000 people on Mars, I don't know, maybe the US is like, hooray, China probably is not. So it's not like, in Star Trek, Earth is a unified front in the...

0:48:14.6 SC: Not yet here in the real world.

0:48:16.5 ZW: No, they're going to be particulars, yeah.

0:48:18.3 SC: Well, you do get a lot and in an admirable way into the legal side of things in the book. So let's just get that clear. How much of legality has been settled for these things? There is, of course, the Outer Space Treaty. That was a long time ago. Maybe we're still paying attention to it, or is this a set of rules that are going to be swept away once we get real?

0:48:43.0 KW: Well, so we hope not. So we are certainly still paying attention to that treaty and a couple others that came in the next decade after that. And those treaties still do things like govern how our satellites move around and who's responsible and you have to register the satellites when you send them up. And so those documents are living and we're using them every day. So then the question is, do the parts that relate to the moon or appropriation of land, is that going to get ignored when we get there? And certainly there are plenty of people who propose that if Earth gets there first, we should just scrap the Outer Space Treaty and sure, it was great. It helped us in some other areas.

0:49:22.7 ZW: If the US gets there first?

0:49:23.4 KW: Yeah.

0:49:24.1 ZW: You said if Earth gets there first.

0:49:25.3 KW: Oh, I'm sorry. Thank you. If the US gets there first.

0:49:26.9 SC: Earth will get there first, yeah.

0:49:28.7 KW: Yeah, yeah. We can feel pretty sure about that. But so some people think you should scrap it, but the important parts of the Outer Space Treaty, the most important part is it says you're not allowed to appropriate land. So if Elon Musk gets to Mars and he says, this is Moscow and this is my country or my city or whatever, that is not allowed by international law. But it is unclear if he's allowed to do any mining on the moon and sell that for profit. And so is that different than appropriation? The US has made it clear that our interpretation is that yes, extracting and selling resources is not the same thing as appropriating that land. That is okay. You can do that. But I think there's some countries, particularly in the developing world, who would say, no, we're not okay with that. The Earth is... Or sorry, the moon is supposed to be, the moon and Mars and all the celestial bodies, that's supposed to be a global commons and you don't get to do whatever you want to it. And so...

0:50:29.7 ZW: Yeah. And it's not just that you can't do whatever you want, I would add that if you try to do something like that, you are antagonizing most of Earth, most of the governments of Earth. It's non-trivial.

0:50:40.0 KW: And power might override. It might be that the US is powerful enough that we're just gonna do it and we're gonna take our chances. We kind of hope not, but...

0:50:47.1 ZW: But the other thing I would add too, and this is, as far as I know, we're the only book that gets deeply into the sort of broader context of international law. They could be very easy to read the Outer Space Treaty as some sort of freako 1960s law where we commonize space, but it was a moment of weirdness. But actually, that's exactly... Not exactly, but very similar to how the Antarctic Treaty system works, very similar to how the seabed works. So every time in the 20th century, humanity was called upon to regulate a newly accessible region of the universe, we picked a commons. And that has been sustained. And the really important thing... Oh, sorry, I was banging the desk. I'm not supposed to do that, bad sound. The other point I wanted to make, so people generally will say to us when we talk about this, they'll say something like well, it doesn't matter because once there's big money to be made in space, all bets are off. We're gonna go get it.

0:51:31.3 ZW: And the thing is, one, we don't believe there's big money to be made in space, but set that aside. In Antarctica, there was a push to make something called CRAMRA happen. CRAMRA, I will never remember what the acronym was. I think the R was resources, but the idea was make it so that the commons of Antarctica could be accessed for resources. And my understanding, and this is iffy, for reasons I'll get to, there's at least some evidence there might've been profitable mineral resources in Antarctica. Remember, it's a whole continent that's never been mined. And in 1998 the consortium of nations in Antarctica decided to put a moratorium, not just on exploiting, but on even looking to see if there was stuff to exploit, that is in force till 2048 and can only be removed by unanimous agreement. So there was a very plausible case for getting resources and the planet Earth said no. And the reasons were that we didn't wanna get in a big giant fight over it and that there was an environmental outcry. So it's not at all obvious to me that we're gonna suddenly go get it no matter what the consequences are if there's money to be made.

0:52:38.1 SC: If I take the words of the Outer Space Treaty literally, does that mean that if someone else goes to the moon and builds a habitat and then I fly up there, I can just walk in and open their fridge and sleep in their living room?

0:52:52.4 KW: You are supposed to give them prior notice and ask nicely, but you are supposed to be able to visit other people's stuff in space. They can tell you, for safety reasons, I can't let you in, but yes, you are supposed to, but...

0:53:10.4 ZW: Yeah. I should say I didn't think you were gonna go there and I love the example of you going to the fridge. By the way, there's no fridge on the ISS. No, I think they just sent up a fridge recently.

0:53:17.0 KW: They just sent up a fridge to the ISS, yeah.

0:53:20.0 ZW: Okay. They have a fridge now. But what's funny, it is actually illustrative because the original agreement really only countenances nations. There was a big debate at the time, but really it's for a two-superpower world. So I don't think they were thinking about a fridge raid by an individual guy.

0:53:36.0 KW: They weren't thinking about Sean Carroll, but they should have been.

0:53:38.5 ZW: I think the rules are more about formal, can we come over to the Chinese module and inspect to make sure you're not doing something that scares us.

0:53:46.5 KW: And to be fair, the space lawyers that I talked to were, I was like, oh, it's so vague and it was made back then and things have changed. And they were like, no, that is a feature, not a bug. We didn't know what was coming. We were vague so that this stuff could get worked out later and we wouldn't be hamstringing everything. And I guess the problem is that back then countries were way more likely to work together to solve stuff. And now you can't get anything related to space through the United Nations...

0:54:11.6 ZW: Well, you can't get any big formal treaty. You can get resolutions and things.

0:54:15.5 KW: Tons of resolutions. Yeah, sorry. Big, highly ratified treaties. We haven't had anything related to space since, what? 1975...

0:54:22.9 ZW: '75, yeah.

0:54:24.4 KW: And that wasn't ratified by most of the countries that mattered as far as going to space.

0:54:28.9 SC: It's interesting, I mean, let's not let that pass by too quickly, our increasing inability to work together on these things. Would you chalk that up more to the fact that when it was less realistic, we were more idealistic? Or is it just that the world in general is less good at working together?

0:54:50.7 KW: So I think that when we first made these treaties, we did think that this stuff was gonna come faster than it did. So I do think that there was concern when we started going to the moon that US would get there first and then maybe they'd start claiming stuff and the Soviet Union might've worried about that. And so they wanted to cut that sort of stuff off at the pass. And so why are we less good?

0:55:16.5 ZW: So yeah, to add a little to that, so we have a quote, there's a guy named Oscar Schachter, Schachtner or Schachter? Okay, his name is Oscar and we quote him. He was an important international relations guy, international relations people know him. He wrote in the '50s that he was concerned about a future where people would plant the flag and make claims like back in the bad 19th century. And so that concern was already percolating. And there's a scholar named James Clay Moltz and we cite him and he argues, I think pretty convincingly that part of what happened is that in the early '60s, I think in '62 and '63, there were high atmospheric and in-orbit tests of nuclear weapons, which so thoroughly terrified everyone that people were willing to come to the table. So in other words, actually, we talk about this as maybe relevant to the current AI discourse is it's like we got space law not because... Well, not necessarily because everybody was so good at working together back in the '60s, but in part because we had scared ourselves and there were enough rational people to say that's scary.

0:56:16.1 ZW: And then the one other thing I would add is there is a kind of pragmatic thing here, which is there are a lot more countries now. So a lot of... The high era of decolonization is 1945 to 1975 There was still a lot to be done when the first... The treaty is signed 1967, the first big proposal, that's basically the treaty is 1963. So there are just a lot more countries now. And there's not this sort of bipolar two big powers that kind of run spheres and people obey them. Like countries can say no to all of us, you know? And so there is just simply a pragmatic aspect. That said, you know, UNCLOS, the Law of the Sea with a lot of negotiating over decades was widely ratified, except not by the us, but okay, and that was 1994. So it's not impossible. But the law of the sea, there was some urgency. There was some urgency about figuring out how territorial waters and stuff works, where space historically, post, let's say like mid-70s has felt non-urgent. And that may be changing with the, the new advances in technology.

0:57:15.6 SC: So we're... Again, if we're obeying the Outer Space Treaty, we're imagining that we have settlements on the moon or on Mars, but they're not... They don't belong to specific nation states, or for that matter, to specific private entities, I guess, same thing would go.

0:57:34.5 ZW: Just slight nuance that the station itself would probably belong to the nation and the company, but the land under it...

0:57:43.0 SC: Land would not. Okay.

0:57:46.2 ZW: Claim the territory. Right? So, to get zany, if you had a base the size of the moon in principle, that base is yours, but the land under it is not.

0:57:53.5 SC: Okay. And I mean, at some point, again, if I get any lessons from all my science fiction reading, a couple hundred years, the moon will revolt and shake off the shackles of Earth and become their own nation state.

0:58:04.7 KW: That does seem like a potential problem to me. Yeah. Especially as a US citizen, we really like having our own property, we like property rights. It's possible that the society that develops on the moon will be less concerned about property rights and stuff. But you can definitely imagine them getting really angry and revolting and maybe one day they get to start their own state. But...

0:58:28.2 ZW: Yeah. So one of the chapters we're really proud of, I don't know if it's anybody else's favourite, but it was our favorite, is one on state creation, which is, you're like, so, there's deep norm in international law. You hear the words, not self determinate... Territorial integrity. Like you've heard... Since the Ukraine invasion, every other word at the UN is territorial integrity. And this is a deep norm that nations cannot be dismembered, and yet countries come into existence from time to time. And it just turns out there's a process and drastically oversimplifying, there's a lot more detail in the book. Generally speaking, it is recognized that if group of people are deeply put upon, deeply oppressed, they may have some right to take part of a country for themselves. Now the standard is very high. There's a big case in 1998 concerning Quebec, which basically said no, although with a lot of nuance, they can't do it essentially 'cause Québécois people, however they feel about oppression, they can vote, they can hold office, et cetera, et cetera. You know, like, as opposed to, say Jews in 1930s in Germany or Native Americans for much of the last several centuries.

0:59:29.3 SC: A long time. Yeah.

0:59:30.1 ZW: Very long time. Yeah, exactly. So the modern law, which obviously was not enforced in the 19th century, but the modern view is there... And the classic case for this is Bangladesh. If a people are under deep oppression by some government, they may have a right to what's called remedial secession. So there... And meaning, so you can do this 'illegal thing' of dismembering a nation, if there's an extreme circumstance that pertains to national identity.

0:59:56.1 KW: And but here for the first time, you'd be taking out part of the global commons and making it the property of a group of people, which would be a sort of new...

1:00:01.7 ZW: Totally new, yeah.

1:00:02.2 KW: Totally new thing. But you can't imagine it working out at some point if they end up feeling super oppressed or if they've been super oppressed.

1:00:09.3 ZW: And so the issue, just to be clear, it's not like you magically get to be a state because you're oppressed. It's just that being oppressed makes you more likely to be recognized by the global community as having a right to a particular territory. So there's some world in which you can imagine for some reason, a moon settlement revolts, and most of the countries from Earth say immediately, yes, that's legitimate, even though they're taking outta the commons. But that's very unexplored territory.

1:00:33.2 SC: Okay. I mean, it does also, it gives me an opportunity to go back a little bit because I think we maybe went a little bit too quickly for my taste over the self-sustainability question. Like, if the moon did wanna secede, they would probably first want to not be dependent on shipments from Earth. So precisely how realistic is that? I mean, let's just say... Let's just say it this way. Is it within present technology if we throw enough money at the problem? Or do we need new scientific breakthroughs to have a truly self-sustaining settlement on the moon?

1:01:08.6 KW: Well, so first I'd say that I think you can get a state made, even if they're not completely self-sufficient. 'Cause no state on Earth is completely self-sufficient either. And so I think the moon could still come up with trade agreements with different countries, but create their own state. But in terms of what it would take to be able to go to survive on your own, I think for us, the clearest example is the need for computer chips to run your habitat is going to very much depend on technology. You're gonna need these computer chips. At the moment, like what all the stations are... All the places that make it are in Taiwan, though we're trying to get one in the US. I'm not completely up to date on all of this, Zach probably is, but these are things that require a lot of water. That it's very complicated factory to make, and they're so lightweight that they'd be... You could ship tons and tons of them on a rocket. You could get a bunch of them to Mars, for example.

1:02:03.5 KW: So it's gonna be a long time before Mars is like, all right, we're gonna make our own chip factory. And also when you think about like you live in a big major country and you've got specialists for all these different kinds of medical problems that you could have, there's something... There's thousands of medical specialties. And so the number of people that you would need to have, like the medical specialists that you need, the professors that you need, the tech or the engineers that you need, we're probably talking about like a million or more people. And what looks like to say something.

1:02:34.6 ZW: Yeah, I was just gonna... I'm glad we'll have the professors that's... [laughter]

1:02:36.6 KW: Well. We're important people, but...

1:02:39.7 ZW: We can do that then.

1:02:40.8 KW: Okay. But so like Cuba and North Korea are not even self-sustaining, and they have the benefit of being able to breathe the air when they walk outside. [laughter] And they still need support. And so you're gonna need huge populations to make this happen. It's gonna be a while.

1:02:57.4 ZW: Yeah. So we did try to find like, is there a good estimate for how many people you would need on Mars to create autarky? And basically the answer is we don't know. There's not a good answer. Oh, so I'm sorry, autarky, economic self-sufficiency. So historically, some communist countries have been interested in this. Probably the closest country is the DPRK, North Korea. But they still have plenty of interaction with the outside world, and also it's awful there. And so we did try to find numbers. There are some very hand-wavy numbers by a couple people. The lowest estimate that we found by a guy who was very pro-settlement was a hundred thousand people. And that assumed extraordinary advances in AI and robotics. So it's a huge, huge number of people. You're not talking, it's not gonna be like a Heinlein novel where there's like a hundred tough guys and then they work it out. It's not gonna be anything like that.

1:03:43.7 SC: That's interesting. Is that demanding a kind of modern first world standard of living? Or is it really just surviving from day to day?

1:03:54.2 ZW: Well, I would say it's a kind of combination, right? So you're right. It's just surviving. But okay, so if you went to... If you found a deserted island with coconuts and pigs, you don't need a lot of technology, right? So you could live a happy non-first world existence. On Mars, you have to have a first world existence in that you will die without like a nuclear reactor and computer chips and all sorts of stuff. So, yeah. So that's the thing is it's not like any situation on Earth, right? You just can't exist without the technology. So you might not need... I don't know, someone running a sauna or luxuries or whatever. You might like them, but maybe you don't need them, but you certainly need advanced technology and that kind of thing. Yeah.

1:04:34.5 KW: Maybe you have fewer medical specialists. Yeah. And fewer professors. [laughter] And, but...

[laughter]

1:04:38.1 ZW: But can't... Oh, go ahead.

1:04:38.3 KW: But, yeah, like Zach said, you need the technology.

1:04:39.1 ZW: Yeah, so I can't remember if we mentioned this in the book, but one thing that was really eye-opening for me in just thinking about this question, so I was talking to an aerospace friend of ours named Manfred...

1:04:48.1 ZW: Yeah, we're saying his name wrong, I'm sure he's from Germany. But anyway, we were talking about this question of could you even model how much energy you would need to run a million people on Mars? And we decided that it would take 30 grad students in 10 years, and it would be wrong by the time you got an answer. But he pointed out, I thought this was a really good observation. He said, on Earth, the cheapest, most efficient way to shift stuff from here to there is on a boat. Right? So somehow if you're calculating your energy needs, you have to factor in that you no longer have free highways between most of the cities on Earth. And so that... And that's just one little thing. I mean, it's like you try to imagine the energy needs you're gonna need when all the things we take for granted go away, it's going to be extraordinary.

1:05:28.7 SC: So it seems like there'd be probably one big metropolis on the moon, not that those million people are not gonna be in a hundred, 10,000 person settlements.

1:05:39.1 KW: Well, it might depend on the distribution of resources on the moon. So you'll probably, you might get them at both poles so that there's enough water. So I guess it might depend on what it is that they're mining.

1:05:50.9 ZW: Why are they there? Yeah, yeah. So Kelly mentioned earlier we have this thing we call premium real estate, which is like, there's actually like the moon, I think has an area about the size of the continental US. And so it's quite big. The actual desirable parts of the moon are teeny weeny. So I can imagine a world in which... So the one thing we didn't talk about is lava tubes. By the way, we're being like pessimistic. Lava tubes is like the coolest thing in the whole solar system. And they're very close to us. They are these caves. So Earth has lava tubes, maybe some of your listeners have been to the ones in Hawaii. Imagine them blown up by like 100X. That might be what they're like on the moon. There are models that at least suggest that. So like these absolutely extraordinary caverns, which would be a great place to set up a base because instead of bringing a habitat or building it on site, you just seal off the walls. Not that it's easy, just seal off the walls in lunar caves. But once you do that, you have your bubble and then you can start doing the other stuff.

1:06:41.8 KW: And that protects you from radiation and from temperature swings and the regolith.

1:06:45.5 ZW: So the popular, when you say a metropolis, like part of the metropolis-ness is constrained by how big the good spots are, right? So it might be more like, if there are only half a dozen really good lava tubes and we know there are only a small number of these places where you can get water in perpetual... Near perpetual sunlight, I would actually guess you'd have a small set of distributed places. Also, I presume that would provide some level of resiliency if something went wrong. But hard to speculate.

1:07:12.5 SC: Did we learn anything from Biosphere 2? How difficult it is to have a truly closed ecosystem?

1:07:21.6 KW: We learned how difficult it is for sure. So Biosphere 2 was 3.14 acres, substantially larger and more complicated than anything that we could hope to make on Mars in the next decade or two. And in that system, one, they had to pipe in oxygen because the cement was messing with their atmosphere and they all were getting like headaches and stumbling around, and so they had to get more oxygen. There were stowaways. There were these bark scorpions, which fun fact are the only lethal scorpions in the US and they had managed to get in there. I think cockroaches also were a problem. There were problems that were getting... So the original plan was to run this simulation many, many times for two year periods and learn as you go. And there was stuff that they were learning, like the chickens that they picked weren't laying enough eggs, and the pigs were trying to eat the chickens, and the mangoes hadn't started... Or was it bananas? One of their fruit trees hadn't started to produce yet. And so, I think it just proves that one of the things that it taught us is that it takes a long time to figure this out. And to be honest, I think it also taught us that you don't wanna start with one giant system. You want lots of little ones where you tinker with a couple of variables and figure out how those work. And then you work on scaling up. It also taught us that human psychology is difficult. So it was what? Six groups...

1:08:41.8 ZW: It was eight people.

1:08:44.4 KW: Eight who split into two hateful factions where they were literally spitting on each other...

1:08:48.5 ZW: Spitting on each other, yeah.

1:08:49.2 KW: When they were angry. And they needed to call out to therapists for emotional support, which is gonna be hard on Mars with a 22-minute conversation delay. You can't have live chats with your psychiatrist if you're on Mars. And so I think there's a lot, you don't want a megalomaniac running the...

1:09:07.6 ZW: No, yeah, I mean, yeah, yeah, yeah. The only thing I would add is, there's eight people in these three acres. They were starving by the end.

1:09:14.1 KW: Yes.

1:09:14.8 ZW: They were, you know.

1:09:16.0 KW: They lost between 10 to 18% of their body mass.

1:09:18.8 ZW: And that is with them working all day on this system just to survive. They're not trying to do cool space people stuff, right? They're just trying to not die. And all the power is supplied from the grid, right? Unless you count incident life on the plants, right? But can I just say, we all make fun of Biosphere 2, and there's so many funny things about it and stupid things they did, but it's worth noting it did basically kind of work. I'm a believer that if... There was no reason to do this, but if the billionaire, they convinced to throw whatever it was, $200 million at this project, if they had continued it for the ensuing 30 years, I do think we would have learned a whole lot because the last textbook written on closed-loop ecologies from like 2003, this is a whole... It's a cool thing. There are a lot of interesting questions you could, what?

1:10:05.7 KW: I can't find that the last textbook on closed-loop ecology was 2003. Okay.

1:10:10.3 ZW: Well, we'll ask ChatGPT at the end.

1:10:11.3 KW: Okay, all right.

1:10:15.2 ZW: But yeah, so the big questions are things like, what is the optimal setup to generate consumables? And almost certainly their system, which was... The guy in charge was this kind of crazy dude named John Allen, who was like three quarters artist, one quarter engineer. And so they did a lot of crazy stuff. They were like, we want a ghost desert, which is not a thing with ghosts, it's like an actual ecosystem. So we want a coral reef. It was like very 90s Captain Planet-y. And so presumably, if they were a little more careful, they probably should have just made the whole thing agriculture and some other stuff, but who knows? Maybe those biomes were really useful. So we could have found out a lot.

1:10:50.6 KW: But I still feel like that money would have been spent better on lots of little ones.

1:10:55.2 ZW: Little ones. Yeah, absolutely.

1:10:55.3 KW: So for example, China has Lunar Palace and they had a situation where they had three crew members in their like closed-loop system and they're breathing gases where it was like too much carbon dioxide was building up. So they switched out two big guys for two smaller women, and then it worked. And that's where we are right now. Like, where you gotta stop around mass to make it work. And so we don't have the science figured out yet with all the calculations you'd want before you send someone to Mars. So there's still a lot to learn.

1:11:25.1 SC: I'm guessing it would make sense, even if maybe it's not absolutely necessary, for the first Martian colonists to be all vegans.

1:11:35.3 KW: Yes. Yes.

1:11:36.6 ZW: I mean, I would... The only thing I would say about that, I'm a vegetarian. You're almost certainly right in terms of like converting energy to calories, but psychology is a thing. You can be... If you look at the very early NASA food, it's literally food cubes and gelatin stuff and everyone hated it. So I do think you want to be open to tolerating some level of inefficiency for sanity.

1:11:57.6 KW: When a lot od the proposals we saw for early settlements they were proposing Mealworms and crickets as like a protein source because those are easy to grow and you can grow them on the like scraps from the vegetable garden. And then there is a lot of proposals for cellular meat. So if you can grow like beef in a vat, and that technology seems to be making pretty good gains, but the closely-loop ecosystem people that I talked to were pushing for like fungus, and you can make fungus taste like lots of different things.

1:12:27.9 ZW: Yeah, vegetarianism.

1:12:28.8 KW: Yeah, vegetarianism, maybe not veganism.

1:12:32.0 SC: Right here on the cover of your book, there's a little perspective drawing of a settlement and one of the very few buildings that is labeled is called Cricket Ranch.

1:12:47.1 ZW: Yeah, very briefly, I guess the evidence is that the bigger the animal, the less efficient you're going to get at converting energy to calories, right? So you're not eating beef, you're not eating chicken, just keep going down, you'll arrive at something like Crickets and that is the set. I mean, again, I mean, there are... I should say we're Americans. There are places where they eat crickets and it's not a big deal and it's not weird, it's a normal dietary item. So maybe just don't send Westerners, send those people there. They're obviously better adapted to this environment.

1:13:19.4 SC: Send the Buddhists, they'll just be happy.

1:13:22.8 KW: Yes Exactly.

1:13:22.9 ZW: Yes, that's right.

1:13:22.0 SC: And I mean, speaking of potentially unanticipated resource needs, we're reading a lot of articles these days about giant computing facilities that are either doing crypto mining or AI calculations, and they need both a tremendous amount of energy, but also a tremendous amount of cooling, right? A huge amount of water is being used up by these. Is that something we're just not going to be able to have on the moon, or is there some more clever way to answer these problems?

1:13:53.4 ZW: Yeah, that's a really interesting question. Fun fact, Biosphere 2 actually had a computing center in its basement. This was 1993 or something. It was called the Technosphere because that's how they did things. And then they actually needed it though to monitor all the ecological stuff. So I doubt it's gonna be on the scale of like some crazy crypto rig or whatever you're doing for these LLMs, but you are gonna need something, right? 'Cause remember again, you're surviving on technology. So if something goes wrong with like the CO2 scrubbing or some weird gases entered the environment or whatever, you do need a system monitoring everything. In terms of cooling, I actually have no idea. I mean, I assume what you'd do if you didn't have water, I guess you could dig down, because these are not seismic... Wwell, they're lightly seismically active. So maybe it would be very cool underground or something. But honestly, I don't know... It's not something we thought deeply about.

1:14:42.5 KW: I think there's enough water on Mars that you could do it without too much trouble. I mean, it would be a pain to get it initially. You'd want to recycle it.

1:14:49.3 ZW: You'd have to get pretty far along, I would think. But yeah.

1:14:53.6 KW: They're working on nuclear reactors for Mars to help provide more power because on Mars you get these dust storms that can last for weeks and they are hard to predict. So you're not going to want to rely on your solar panels. So you could use some nuclear power too.

1:15:08.0 ZW: But I would just say questions like that are part of why this is so difficult because you tend to think in terms of like, well, we need a box of oxygen and some food. But actually there's all this little stuff for survival.

1:15:18.9 SC: All right, we're reaching the end, but I have a couple of very easy questions to wrap up with. One is, we already touched on this a little bit, but war in space. I think part of the Outer Space Treaty is you're not supposed to send weapons up there, but it's a little bit vague on military operations more generally. I mean, is this... As we might have imagined back in the 60s, is this a whole new theater for good old nationalistic countries to work out their aggressions on each other.

1:15:54.9 KW: So you're not allowed to send weapons of mass destruction. So I think technically you could strap a gun to your satellite and use it to shoot another satellite. But that would be very much frowned upon. So at the moment, I think it's mostly folks don't want to be starting an arms race on the moon. And in the United Nations, there's resolutions all the time to how are we going to deal with this potential emerging arms race in space? We already from land shoot down satellites that are in space and we've never shot down another country satellite, but we have shot down our own country satellite just to make sure everyone knows that we can do that.

1:16:37.9 ZW: Russia actually threatened to do it. Go ahead.

1:16:39.0 KW: Yeah.

1:16:41.2 SC: Didn't China shoot down one of its own satellites from space? Didn't get in trouble for doing that?

1:16:46.4 ZW: I thought they had shot a ground-to-space missile, but I think...

1:16:48.9 KW: I think it was ground-to-space.

1:16:49.3 SC: Oh, was a ground-to-space.

1:16:50.1 KW: And they got in trouble because it was high enough up that the debris is going to take a really long time to fall. And that was what got them in trouble.

1:17:00.1 ZW: So, t To compare, India did an ASAT test, I think, in 2019. People frowned upon it, but it was in very low Earth orbit. So it was less of an environmental issue.

1:17:08.9 SC: We didn't even mention space trash and space debris overall. Is that overblown or is that going to be one of the real concerns?

1:17:17.3 ZW: We have less expertise on that. I mean, space is really big and it hasn't been a problem yet. I do think there's a tendency to think crazy space billionaires, because they're crazy space billionaires, don't care about this stuff. But there are actually systems in place for everyone to communicate with everyone and to move stuff up and down.

1:17:30.5 KW: I mean, I wouldn't want to be living in a rotating space station in low Earth orbit with all that debris, but I wouldn't worry about it if I was on the moon or Mars or L5 or something like that.

1:17:41.1 ZW: Right. Yeah. I mean, you have to remember it's like, so if you go to 300 miles, that's one shell. If you go to 310, that's another shell. 320, that's another shell. I mean, of course, everything's going quite fast. But, I mean, for example, there are... I forget the exact number, it's something like 37 nuclear reactors are in space currently between, I think 700 and 1000 miles high. And I don't think, it's obviously a weird thing to say, but I don't think people actually worry too much about them.

1:18:03.7 SC: Nuclear reactors in space. Yeah.

1:18:06.9 ZW: It's fine.

1:18:09.0 SC: Absolutely true, but we don't really worry about it that much. Okay, so then here's the last question. We sort of squirted around this one. How much is this going to cost? Like, it seems like it'll be very expensive to put a million people in a city on the moon. And maybe we can fold into this, if you done a very, very good job, I think of letting us know all of the worries and maybe the extent to which people don't take the worries seriously enough. But if we allow ourselves to be a little optimistic, when could this possibly happen if everything broke right for us? So how much does it cost and when is it going to happen?

1:18:44.0 ZW: Sure. So cost, I mean, so let me just say a priori in both these questions, I'm going to have to be fairly hand wavy. But so on the...

1:18:54.0 SC: I will allow you.

1:18:57.1 ZW: On the question of cost, it's tough and I'll tell you why. So if you look at the International Space Station, there are different estimates on what that has cost so far, but it's something like 150 to 200 billion dollars. Extraordinarily expensive. That's for six... A crew of six in a room about the size of a nice apartment. So, what a person, a space advocate would say, I think correctly, is that as costs fall, that'll get way cheaper. And but as, I think Jonathan McDowell pointed out to us, the modules are a huge part of that cost. It's not like launch is doing everything. Those modules are very expensive. But so the thought is... And you get to a world where you're actually mass producing the modules like for space hotels or whatever, then maybe you can really drop down the price. I mean, so we talk about how... Depending on how you count it and you can get a little fuzzy with the numbers, but between 1957, say, and 1970, the cost of going to space, putting stuff into orbit anyway, dropped by maybe as much as 99%. It hasn't happened since, but since 2015, there are different estimates, but let's say it's dropped by like three quarters. That's a pretty fast decline.

1:19:55.6 ZW: So what I'm saying is essentially there are reasons to believe it'll be zany expensive, but the scaling the rocket launch really does matter. And in ways you might not anticipate, it's not just that it's cheaper to get stuff to space, it means you can use more off-the-shelf parts because you don't have to fit it exactly in the fairing of the one vehicle you have. So there is a huge amount of room for cost drops, which is part of why we got interested in this topic in the first place. So I really wouldn't want to give a number, but I would say it's a huge number. It might be smaller than you think. I think if the US decided tomorrow, we have to have a moon or Mars base with a thousand people, you're probably talking trillions. You're talking about a zany amount of money. But in terms of the space business scaling over the next 50 years, there are possibilities. It's very path dependent. If Lockheed Martin said they were making a compact fusion device, I don't believe them, but suppose they did, that would change the equation a lot. In terms of time scales...

1:20:58.0 KW: I think time scales, it's so hard to predict because it really depends on what people decide is a priority. And so, if the US decided we are absolutely in a space race with China, the president and everybody in the Senate agreed, we threw a ton of money at it, we could maybe make that happen soonish. But I don't know, but the whole... A huge part of our book is arguing that we shouldn't be doing it as fast as we can. We should be stopping and first we should be doing more biology experiments to get a handle on the risks so that we can reduce the ethical problems. And if you've got more time, maybe you can work out a system with the international community for who gets to extract what and how are those profits shared? And do you get to decide that this land belongs to a certain group of people so that they don't revolt in 200 years? And can Sean Carroll eat your ice cream if he shows up on the moon? Like probably the most important question. And so...

1:21:56.9 SC: Very important.

1:21:58.9 KW: We would like to see this take decades, but it could be rushed.

1:22:06.2 ZW: One last little thought on that, which I've been thinking about recently is, we said earlier the lowest bound number we'd ever found on self-sustaining settlements was 100,000. And it was based on an assumption about huge developments in AI and robotics. And I kind of laughed about it two years ago. And that's changed. And so it's funny, there's still parts of those proposals I'm skeptical, but you wonder about if in 20 years, there's a world where we have fusion figured out and you can just send robots to set everything up in advance. That really does change the picture. So that's why we're very uncomfortable predicting because the place from which the advance comes may be surprising.

1:22:42.4 KW: Yeah.

1:22:44.0 SC: Well, I did a few months ago talk to Joseph Silk, who is a very well-known cosmologist who just came out with a book proposing telescopes on the moon, right? Astronomy on the moon. And there's very good science case to be made for them. And he mentioned, his book just came out like earlier this year, he said, when he was writing the book, he said, you're gonna need human beings to maintain the telescopes. And by the time the book came out, he's like, well, yeah, maybe we could have an AI and a robot maintaining the telescope. So a whole new existential risk has opened up because we're gonna make a city of robots, artificially intelligent robots on the moon and give them high technology. What could possibly go wrong?

1:23:28.7 ZW: Yeah, I think to button that up, to me that speaks to the nature of the problem, which is like, there's like a Heinlein vision and the Star Trek vision. And Heinlein is a hard scrabble, we're gonna do this as people. Star Trek is the world has worked out, so we're doing it for aesthetic reasons. I think that's much more plausible.

1:23:43.3 SC: Hmm, all right. I like that. That's a wonderful place to end. Kelly and Zach Wienersmith, thanks so much for being in the Mindscape Podcast.

1:23:51.1 KW: Thanks for having us.

1:23:51.3 ZW: It was great. Thank you.