From Earth orbit to the Moon and Mars, explore the world of human spaceflight with NASA each week on the official podcast of the Johnson Space Center in Houston, Texas. Listen to in-depth conversations with the astronauts, scientists and engineers who make it possible.

On Episode 266, lunar seismologist Dr. Ceri Nunn joins us from NASA’s Jet Propulsion Laboratory in California to talk about moonquakes and why studying seismic activity on the Moon is important for the future of human spaceflight. This episode was recorded on August 22, 2022.

Transcript

Pat Ryan (Host): Houston, we have a podcast! Welcome to the official podcast of the NASA Johnson Space Center, Episode 266, “Moonquakes;” I’m Pat Ryan. On this podcast we talk with scientists, engineers, astronauts, and other folks about their part in America’s space exploration program. And today we’re going to focus our attention to what’s shakin’ almost a quarter of a million miles out in space. I have been lucky enough to have lived all of my life in parts of the United States that are not prone to earthquakes; haven’t avoided hurricanes, but no earthquakes. On top of my limited knowledge of quakes-of-the-Earth, it seems that I recall having been taught that Earth’s only natural satellite, the Moon, is a dead body that doesn’t have any quaking. Well, it turns out, that’s wrong. The Moon does have seismic activity, ground motion, and since we’re going back there in a few years we best learn all we can about it. Today, we’re going to do Intro to Moonquakes with lunar seismologist and planetary scientist Dr. Ceri Nunn. Nunn has a doctorate in seismology from the University of Cambridge, which she followed with a one-year postdoc at Durham University in the UK, then a fellowship at Ludwig Maximilian University in Munich, and then another at the Jet Propulsion Laboratory, where she is now a research scientist using seismology to study the structure of the Moon, and she’s currently involved in a number of NASA missions that are rewriting what little I thought I knew about lunar structure. So let’s get educated: here we go.

[Music]

Host: For those of us of a certain age, as they say, it was once a scientific fact that the Moon was a dead body. There was no life there: no water, no air, not even any vibrations, except when it got hit by a meteor digging a, a new crater. Ceri Nunn, when did science start to realize that there actually was seismic activity on the Moon?

Ceri Nunn: Well, that’s really interesting because it’s, it’s not really until Apollo 11, and even then nobody’s quite sure because what happened with Apollo 11 is they took a seismometer, and it had these crazy signals like, just nothing we have ever seen on Earth. The signals, they like for over an hour, even for really small; they can, you know, they rise very slowly, and they decay even more slowly. They, they, they just, it almost like a soundwave, but for an hour. They’re just like this…

Host: Wow.

Ceri Nunn:… crazy, crazy signal. And so, like what, so of course one of the first questions that they had was, had they just set it up wrong? You know, that they’ve done something, you know, something wrong with the seismometer, the way it’s installed, or even the way it was digitized, that just something went wrong. And so, they had many, many signals like this. Some of the, they did see some, the footfalls of Buzz Aldrin that’s kind of on, on the short-period seismometer, but they said that they see these on much longer signals on the, on the mid-period seismometer. And so, yeah, they, they just look crazy. And it actually wasn’t until they, they deliberately crashed the, the spent lunar ascent module from Apollo 12 a few months later when they, they see something so similar to these kind of long natural signals, they’re like, oh, OK, you know, we know, we know that something can, you know, that far away and that, that kind of size can create a signal that’s really similar. And yeah, so that’s kind of where they, they, they began. And one of the first things, I guess, so one of the other things which they would’ve considered was that maybe the sources themselves just take an hour. You know, there’s something, maybe there’s some kind of rumbling or some kind of a tremor or something, so, that they realized with this impact that that’s not true and that you can just make it, you know, you can impact something that’s, you know, over two tons into the lunar surface, you know, the impact’s really quick, but it generates this really long signal. And then kind of from there, sorry, carry on.

Host: Well, I was saying we, we can, we’re going to get back to that in a second, I think. I want to ask you how you got interested in, in this, in the first place. Now, you’re talking about something that happened more than 50 years ago, so the, the, the data, the, the, the knowledge has been around; how did you become interested in, in seismology and, and studying the Moon?

Ceri Nunn: Ah, yeah. So I was, I was captivated by the Apollo missions themselves, and particularly the geology of it and the way that it was a very science-driven mission, and had been fascinated for a long time. But it’s actually the InSight mission to Mars that that was kind of, you know, getting, you know, they were, they were preparing the InSight mission to Mars, which is a seismic mission to, to study Mars, and as I was finishing my Ph.D. I was looking around for something to, you know, to get involved in that. And, but I really wanted to do something very data-driven, and so the obvious choice was the Moon because there were, you know, over 13,000 signals. And they, you know, they sit there in the archive. So for a data-driven scientist, it was, it was the kind of obvious next step…

Host: When say 13,000 signals, you mean like recordings of 13,000 seismic events?

Ceri Nunn: Yeah. Yes. Of all different types. So we’ll perhaps get into that later, but yeah, different types and even more of, you know, thermal events. So yeah, there’s, there’s many, many, many signals to, to look at on the Moon. And the, the seismometer has run for, some of them are over a year. So that was, that was kind of where I wanted to, you know, that was where I wanted to focus. And so what I did was write a fellowship application to apply some new techniques, which we use on Earth, to try to get, what I wanted to do was get the depth profile so basically look at how the, how the, how things change as you go down into the surface, from the surface down.

Host: Right.

Ceri Nunn: And then, unfortunately that technique didn’t work. It was partly because the, the, the seismic phases that we used to do this on Earth just get scattered out on the Moon. But by then I was hooked, and I just fascinated by the way that the Moon just doesn’t behave like Earth.

Host: Right; interesting. Tell me about that, that progression in your academic career, because as, as people can hear, you’re not from around here, not in, not from California or from Texas?

Ceri Nunn: No. Not from California. No, no, I’m not, no. I, I’m originally from the UK and I did a Ph.D. in seismology in, in Cambridge. And then I did, I, I did some more work on terrestrial seismology, but then after that I started looking at the Moon and then I did that in Munich before moving to JPL (Jet Propulsion Laboratory).

Host: And what, were you involved in, in lunar seismology when arriving at JPL?

Ceri Nunn: Yes. Yeah. So, so that was, you know, it was actually, I got hired to look at non-Mars seismology. So the Moon was perfect, and some of my colleagues also work on the icy moons [of Saturn and Jupiter]. So, yeah, that’s what I did back from the start.

Host: OK. Now, if I, if I can back us up a bit, it sounds like what you’re saying is that, that nobody really had any insight that there were any moonquakes until the first instruments were put there on Apollo 11, right?

Ceri Nunn: Yeah. So what, what they did guess that they were, were meteoroid impacts; you know, the meteoroids, you know, they have to hit the Moon. There’s no atmosphere so nothing slows them down, so they have to hit the Moon and we can see, obviously see huge amounts of evidence of them hitting the Moon. So they knew they were there. And they also guessed that there would be thermal quakes that as the, you know, such a large temperature variation on the Moon that the rocks just crack and break.

Host: And you say, you call that a thermal quake?

Ceri Nunn: A thermal quake, yeah. So they’re quite, you know, they’re, they’re quite common on the Moon, especially at sunrise and sunset. And so they can’t, I don’t think they, they expect it, though; I don’t think anybody really knew whether there would be something internally, but yeah, it wasn’t until they, and of course, the other thing is they weren’t sure how much noise there would be: whether there would be, you know, whether the noise of, of everything happening would be higher than the individual signals. So they didn’t know that either. But I think that, you know, nobody was particularly surprised that they saw meteoroid impact but they didn’t expect how, you know, how they would look.

Host: In those cases, though, aren’t we talking about vibrations or, or whatnot that are the result of outside forces, meteorites hitting it…

Ceri Nunn: Yeah. Yes.

Host:…or, or the, the temperature changing it, but, but not generated from within the Moon…

Ceri Nunn: Yes.

Host:…if you will, naturally.

Ceri Nunn: Yes. Yes, exactly. Yeah. So, so those are the expected ones. And then, and then internally, so they, they started, so again it kind of came quite gradually that when they went to, as they added another station then you can see that the, that some of the signals arrive at roughly the same time. And in order to get the signals to fit, they have to be quite far away. And then later when they have Apollo 15, they can actually get three of these, you know, that, that the signals are being picked up in three stations, and then later with Apollo 16 they can get four stations. So then they start to work out that some of these signals are actually from inside the Moon, and they’re, they’re pretty common and they seem to be tidal and triggered, so at certain phases of the tidal cycle, that’s when they, when they come.

Host: And we’re talking about the tides on Earth?

Ceri Nunn: Yeah. So it’s, it’s the Moon’s response to, as it goes around the Earth and of course, it’s, it also interacts with the Sun so you have, you have a different tidal cycle as you go through, through the months.

Host: Well, it’s interesting, we, we are taught that the tides on Earth are in, in some ways are impacted by the Moon; now, to think that the tides are, are also impacting seismic activity on the Moon.

Ceri Nunn: Yes, yes, they do. You know, we, we have, you know, the Moon’s smaller than us but, you know, we, we have a, we have an impact on the Moon, and it’s obviously a bit short on water so there’s no, they don’t have that kind of tide…

Host: Right.

Ceri Nunn:…but yeah, there’s body tides like within the Moon itself that are changing.

Host: And a moment ago you talked about how on subsequent Apollo missions they were able to get readings from multiple stations; are you talking about seismographic equipment that was left behind at each of the Apollo landings?

Ceri Nunn: That’s right, yeah, yeah.

Host: So those, those were still operating after the astronauts left?

Ceri Nunn: Yes. Yeah. That’s, that’s where we get the majority of the data from. They weren’t turned off until 1977. So with, with most of the missions they added new seismometers, which were doing this kind of listening. And yeah, they, by the time, you know, once Apollo 16 is there, most of the time you have four stations operating.

Host: Wow. Now, how much of science on Apollo missions was aimed at studying lunar seismology as opposed to other kinds of science that, that folks were interested in?

Ceri Nunn: Yeah, I think that, you know, one of the really cool things about the Apollo missions with how science-driven it was, and geophysics is really important but there are actually other instruments and other, you know, other experiments going on at the same time. And of course because they’re going on at the same place, you can, you know, people can work together to get certain aspects from, from those data, so there were, they were measuring the magnetic field, they measured the heat flow coming from, you know, the center of Moon, they, they measured the solar wind as well. So there was various experiments. The seismic experiments were really important, I think, because it was, it was kind one of the main focuses, but, but still there was really cool stuff. And of course the geology and the observations that the astronauts made, and then the sample return was, was really important in terms of Apollo science.

Host: Right. Well, they were the first people to go there and scientists want to know everything, and I’m, I’m sure they were fighting with each other to get their different kinds of experiments.

Ceri Nunn: [Laughter] Yeah. No, I think, yeah, they definitely were. There was a lot of grumbling, I think, about, oh no we haven’t done this, or we haven’t done that. But yeah, I think overall the, the overall focus of being, you know, very science-focused is perhaps a little bit of a surprise, certainly to me but, you know, you think of it as, you know, a human exploration mission, whereas a huge part of the human exploration was to gather data for, for science.

Host: Right, right. Now, talk about some of the, the different ways that the, the Apollo missions gathered data. You, you made reference before to crashing one of the components of an Apollo into the surface…

Ceri Nunn: That is the experiment I want to do again! [Laughter]

Host: Well, OK…but I mean, did, did they just, you know, put seismographs on the surface and then, and, and get the readings of whatever happened to happen, or did they, what, what other kind of purposeful things did they do to, to generate some readings?

Ceri Nunn: Yeah. So they, yes, they, they crashed the, the Saturn IV boosters into the surface. They crashed the lunar ascent modules. They also, they did some active experiments where they had grenades, where, luckily, I think the grenades were detonated after the astronauts left.

Host: Oh, ok.

Ceri Nunn: But they, you know, so they’re kind of, you know, they’re looking at, because they’re generating a signal and you can see the, you know, like a kilometer or something into the surface to get a really nice seismic reading from, from doing that. And then much smaller ones where they were kind of like a little thumper which, and that’s really small, it’s like on a kind of 10-meter scale, but, and that gives you a reading into like the first one or two meters of the surface. So you’ve got this kind of, you’ve got this range of, you know, from like one to two meters, around a kilometer, and then right into the depths of the Moon. Some of the, you know, the deep moonquakes themselves might be 700 or 800 kilometers deep.

Host: Wow.

Ceri Nunn: So you’re getting this range of, of, of observations from, you know, different ranges and different timescales which, which was really helpful for trying to make a picture of the whole Moon.

Host: Well, that leads into the basic question, I guess: after all of the research and, done on these Apollo missions and the data gathered over the course of the several missions, what can we say we learned about the Moon’s geology and, and the seismic activity there?

Ceri Nunn: Yeah, so I think probably the most important thing is to do with the structure of the Moon. That the Moon has a core, a mantle and a crust, and the crust be probably around, you know, 30 kilometers on average, like that kind of thickness.

Host: OK.

Ceri Nunn: So, and then the core would be maybe 380 kilometers. So what you also get is, you know, you, the mantle is a bit different from Earth’s, you don’t get it layered in quite the same way, and the core would be a partial melt layer, but it’s, it’s looking somewhat similar to the Earth. But what was obvious right from the start, I think, is that you have this very important scattering region. And what happens is that you, because the meteoroids have been bombarding the surface for 4 billion years…

Host: Right.

Ceri Nunn:…you get, what you get is this very fractured surface and there aren’t processes like on Earth to kind of close up those fractures. So what you get is a region, probably around the edge, maybe possibly as much as a hundred kilometers where it just, you just kind of, if you get a seismic wave in there it will kind of stay and bounce around and bounce around until eventually it, it attenuates and, and there’s nothing left of it.

Host: Right.

Ceri Nunn: And that, what we see, right, you know, the seismograms I was trying to describe, you can’t have a seismogram that goes on for an hour unless you have something like this. And that’s perhaps one of the biggest differences between the Moon and the Earth is that this scattering region and is really, really important. And yea, I can…

Host: Is it correct to say, and I’m trying to characterize it in my head, is it like the, the, the seismic waves are echoing around and the fact that they continue for an hour is what’s so surprising?

Ceri Nunn: Yeah, I think so. I think what, what we think is that, that there’s like some kind of space to the scattering layer, and so they’re being sent back up to the surface, and so they, they’re not being lost in the whole Moon, they’re kind of being stuck in this static layer. And then, yeah, there’s this part that you described with it echoing around is, is quite important.

Host: That’s, that’s, that’s interesting. Now, we’ve been hearing lately about how people who are studying some of the samples brought back from the Moon are learning new things by applying modern techniques to examining the actual samples that were brought back to Earth; has subsequent study of the, the seismic data led to any new discoveries?

Ceri Nunn: Yeah, I think so. And I think, so there really was some, you know, heroic effort to preserve these data that, you know, kind of searching in old garages and various other things, there was, you know, some of it, some of it got preserved correctly at the, you know, in the data archive, but there was various clips that got, were missing. And so, but, but that’s, that’s kind of really important because as you say, you can have some techniques, you know, 20 years in the future, and so, yeah, I think some of the work that we have, have on the lunar core comes back is that, you know, sort of 20, 30 years after the effect, after the data were collected that we manage to process these very tiny signals from the lunar core. So yes, I think, you know, knowing where the lunar core is, is, is one of those things. I think right now, the, the biggest, the most exciting thing is, is using machine learning techniques because you can, it’s, it’s a lot easier for a machine to read 13,000 samples than it is for a person. And so, there are a new, we are actually getting some new information about the time of some of the thermal moonquakes, which came from actually came from Apollo, from the landers. But sometimes the landers are having these kind strange signal and we’re learning about when they happen so that we don’t make the same mistakes, basically, and have our data contaminated by thermal noise. So yeah, definitely, and, and I don’t think that that process is over yet because, you know, these, these data were collected on the near side of the Moon, some future missions will be, you know, in different parts of the Moon so we may be able to use comparisons. Obviously, they won’t, they won’t be simultaneous but we still think that they’ll be useful information by comparing the original samples to the new ones.

Host: You reference there that data from landers; do I understand that these are landers that have landed since Apollo?

Ceri Nunn: No. So we, the, there’s, there haven’t been any seismic missions since Apollo 17 left in 1972.

Host: OK.

Ceri Nunn: But there are some, there are some missions like in progress that may be landing really soon, you know, like the next two years. So the, the Indian space agency is, is taking Chandrayaan-3, hopefully in 2023, to the, to the lunar South Pole. Chang’e 7, which is a Chinese mission, will land again near the South Pole, hopefully in 2024. And the Farside Seismic Suite, which is a NASA mission, is due to land on the far side in 2025, so that one is going to Schrödinger crater. So hopefully there will be some new data in the next three to four years.

Host: Well, and that’s a good thing; let’s talk about some of the, the new missions that are coming, particularly ones you’re working on. That would be the, the Farside Seismic Suite is one of them, right?

Ceri Nunn: Yeah. So the Farside Seismic Suite is a NASA mission. It’s due to go to Schrödinger crater, which is on the far side of the Moon, it’s quite far south, and this will be the first seismic mission to the far side. So that’s something which is, is quite exciting.

Host: Yeah.

Ceri Nunn: And it’s, it’s going to be a couple of seismometers. It’s part of NASA’s commercial program, so it, and it will sit on the deck of one of the new commercial landers. So it’s, yeah, it’s a, like a fairly small mission with these two seismometers to a single place, but somewhere we’ve never been before.

Host: Is that the, the, the particularly new and exciting part of it is, that the area where it’s going?

Ceri Nunn: Yeah, so it’s, it’s going to Schrödinger crater, which is, it, it’s, it’s 3.8 billion years old, which is quite, quite young for the Moon. [Laughter] It’s, it’s 150 kilometers in diameter. It’s really beautiful, and it has a, a peak ring structure, so it’s one of those craters with like a concentric ring in the middle and then a crater rim around the outside. And it looks a little bit, it’s got a lot of similar, similarities with Chicxulub, which is the dinosaur-killing crater on Earth. But of course, on the Moon it’s much better preserved, you know, that there’s, it, it’s, you know, it’s still sitting there. So it’s kind of something of a, a museum piece. So yeah, we’re really excited about, you know, going there and looking at the crust there.

Host: You said this is supposed to launch in 2025, and how long does it take to get there, how long will it be working, gathering, gathering data?

Ceri Nunn: I don’t know exactly how long it, it, it’s not, you know, the Moon’s not that far in space terms, and the, the mission, the nominal mission is four months. So yeah, and one of the cool things about the technology of this is that we’ve got, we’ve got something to have it make sure that it works through the night so that we can take it, we can use it both day and night, which means that we get a continuous record of like four months.

Host: Now being, being on the far side of the Moon, how do you get the data home?

Ceri Nunn: Well, we’ll be able to store it part of the time on the lander, and we’ll have a relay satellite, which will, but that will be sort of further behind the Moon.

Host: OK.

Ceri Nunn: So it’ll be able to send, to send the data back to us.

Host: Are you using some new sorts of equipment that you, you hope is going to get you newer insights?

Ceri Nunn: So the, the big difference that we have, we have a, a slightly more sensitive seismometer. We have one seismometer that, that measures in the vertical dimension, and that one’s a bit more sensitive than Apollo, so that’s really exciting. We, you know, Apollo, the Apollo missions were recording, sometimes it looks quite flat, we can’t really see very much, and that’s because you just, you know, this seismometer isn’t sensitive enough to, to do what, what you need it to do. So we’re going to be a bit more sensitive, that’s really cool. We’re also, the Apollo missions were very coarsely digitized; you know, this is, you know, this really is 50- or 60-year-old technology where digitization was pretty new, and like the bandwidth to carry it was probably the biggest problem. So they were very coarsely digitized. So what they, actually a lot of the seismic signals looks like, you know, when nothing much is happening, it looks a bit like a barcode because it’s really, really flat, and then something happens and then it’s really flat and then something else happens and it’s just, we can hopefully get rid of that problem. So we will, you know, we’ll be able to get slightly more sensitive signal, just, just below where we were before. So, so yeah, those are the two, the two, not even innovations but because, you know, it’s, it’s been so long since the original, you know…

Host: It’s just new data.

Ceri Nunn:…data, yeah. New data. Yeah.

Host: Now, I understand you’re also working on another one called the Lunar Geophysical Network. Tell me what that is?

Ceri Nunn: Yeah. So that’s going to be, this is a, a mission which should be proposed in the next two to three years. And this would be a global mission. So you can, you do the same thing as Farside Seismic Suite but you do it in four places simultaneously with very sensitive seismometers, and you, because, and also with other geophysical information like a heat flow probe and, so that is, that kind of global coverage means that you can answer, you know, even more questions that we, we still have. But what we’re, one of the things that we’re really interested in, both for Farside and for Lunar Geophysical Network, is what’s the difference between the near side and the far side. That, the original Apollo missions were all on the near side and they just didn’t pick anything up from right around onto the far side. But I’ve always suspected that’s just because of where they were, rather than that there’s some major difference between, you know, the far side and the near side. But now we can test it, so we can see whether there’s any major differences in terms of seismic activity on the far side to the near side. And we can also, because we know that the Moon itself is very asymmetrical, you know, that even just looking at the surface, the surface, the far side surface, doesn’t have as much of the maria, which are the lava flows which cover the near side craters; if you look at the Moon from Earth, you see those really dark circles.

Host: Yes.

Ceri Nunn: And they’re the maria. But they don’t exist on the far side. So, they, so, so we know this, you know, just from some observations we can make from orbit that there’s these huge differences between the near side and the far side. So I’m really interested in how that goes into the, you know, how far that goes into the Moon, whether it changes the crust or the mantle or even potentially the core. So, so yeah, those, that would probably be one of the things that we’re really interested in for the Lunar Geophysical Network. And the other thing is to do with, again, differences: there’s some regions on the near side which have very high heat producing elements, where there’s just a lot of heat flow coming from these regions, and we think they’re probably pretty shallow but I’m not sure that we’re completely sure. So again, looking for differences between, like, if you’ve got one of your seismometers inside and one outside, and you also put a heat flow probe in the same place, and just compare and see how deep those structures go. So I think that, yeah, it’s really exciting if we can, if we can get that one agreed.

Host: And you made that sound like that was going to be not just a NASA mission, but there were others who would be involved.

Ceri Nunn: So some of the, this is overall a NASA mission, but some of this will come, from, from other, other…

Host: The other partners involved.

Ceri Nunn: Yes. Yeah.

Host: OK. Cool. Those are really interesting missions to, to find out more about the Moon. I understand you’re also involved with missions trying to find out about the, the seismology of Mars?

Ceri Nunn: Yeah, yeah. So I’m working on the InSight mission to Mars, and the InSight mission has, it’s a, it’s a seismic station in a single place on Mars. It’s been, it’s, there’s been many, again, many marsquakes that, that’s kind of, that’s slightly a smaller surprise than the moonquakes, but you know, because a lot of the, a lot of the marsquakes that we can see are from, from a region of the, the Cerberus Fossae region. And you know, you can see those from the, you can see these, the, the rift across Mars from the satellite, which is, you know, they’re like a thousand kilometers long. So I don’t think it was a huge surprise; obviously it was a huge success that we were able to pick up those signals. And you know, that again, that the noise wasn’t in doing the wrong thing. On Mars the wind is a huge problem, which luckily I don’t have that problem on the Moon…

Host: Right.

Ceri Nunn:…but we do have that problem on Mars. And so, so yeah, that’s, there’s a lot of signals and, it’s also been the case that the Mars extended mission has been even better than the original mission. So there’s been a lot more seismic activity and, favorable conditions to pick up these, these Martian signals.

Host: Interesting. Boy, with, with all of the, the effort that we have going into now into Artemis programs to, to go to the Moon and, and later to Mars, it, it, it seems to me reasonable to want to know as much more about the, the geology and the seismology of the places that we’re going. Is, is, what do you think it is that we can learn from these missions that will inform our planning for human missions to these places?

Ceri Nunn: Yeah, so I think for us in this particularly, you know, the, the shaking for one hour, you know, the, moonquakes for one hour, doesn’t sound much fun. And, and human structures have to be able to deal with that.

Host: Right.

Ceri Nunn: And secondly, you know, the, the micrometeorite, one of the things which we want to do with Farside is look at the micrometeorite. And, you know, we know that there are a lot of them. We know, you know, they come in very, very fast because there’s nothing to stop them. Although, I think, it’s been estimated that the chance of being hit by something, say, like ping pong ball size, is one in a million, which I think, I’m sure the astronauts kind of reasonably happy with…

Host: Yeah.

Ceri Nunn:…but things which are smaller and will almost definitely damage human structures over time, is something which NASA is very conscious of and obviously any other space agencies are very conscious of to make sure the equipment is robust to that. So I think in terms of planning those, the, the human exploration missions, that’s what some of the things that the seismology can tell us.

Host: To know more, as much as we can, I guess, about the, what, what the ground we build our stuff on is going to do?

Ceri Nunn: Yeah. Yeah. We can, we can also, we, we can also look at, you know, the, the surface and the subsurface. So there has been some talk of longer term human activities on the Moon involving something like, you know, lava tubes or lava pits, where these are holes in the surface where, you know, the lava has flowed through originally. And, and so you, you can put your human structures in them and they’re slightly, you know, they’re safeguarded in certain ways from the excesses of the lunar environment. And that’s something that can look for on, you know, with, with seismic missions. So yeah, we, there is, there are definitely things we can do about the structure and, and knowing, I guess, also how, you know, how solid the structure that you’re going be building on, you know, we do know that there’s a lot of dust on the Moon and we know like how thick that is.

Host: Right.

Ceri Nunn: That’s something which comes from the seismology, particularly. And yeah, that’s another issue which people have to consider.

Host: It’ll be fascinating to see what you learn from the future missions and, and can add to the body of geologic knowledge of the Moon. It’d be very interesting.

Ceri Nunn: Yeah. Yeah.

Host: Ceri Nunn, thanks so much for taking the time to educate us about what’s going on here. I appreciate it.

Ceri Nunn: Thank you. It’s been really fun. Thanks for inviting me.

[Music]

Host: There is so much that has to be done to support the Artemis missions to return human beings to the surface of the Moon, and this time in a sustainable way, to learn more about the place and how we can live there long term and use the Moon to support deep space exploration. There are new rockets and spacecraft and lunar vehicles and such to design and build, and plans for and methods of establishing the infrastructure to support that human activity on the lunar surface. And there’s a need to learn about that surface, the place where we plan to build facilities that will last. The hard science that Ceri Nunn and her colleagues are doing is another important part of NASA’s plan for future exploration. I want to remind you that you can go online to keep up with all things NASA at NASA.gov. In fact, you can get all the NASA news you want delivered to you every week, if you go to NASA.gov/subscribe to sign up for the NASA newsletter. You can find the full catalog of all of our podcast episodes by going to NASA.gov/podcasts, scrolling to our name. You can also find the other exciting NASA podcasts right there at the same spot where you can find us, NASA.gov/podcasts. This episode was recorded on August 22, 2022. Thanks to Will Flato, Gary Jordan, Heidi Lavelle, Belinda Pulido, and Jaden Jennings for their help with the production. And to Ceri Nunn for shining a light into the dark craters of my knowledge of lunar seismology and helping us all understand more about that spot in space that humans will return to in just a few years.