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 248, David Blewett details a mission to investigate the mysterious lunar swirls. This episode was recorded on May 27, 2022.
Transcript
Gary Jordan (Host): Houston, we have a podcast! Welcome to the official podcast of the NASA Johnson Space Center, Episode 248, “Lunar Vertex.” I’m Gary Jordan and I’ll be your host today. On this podcast we bring in the experts, scientists, engineers, and astronauts, all to let you know what’s going on in the world of human spaceflight. Twisting and turning across the Moon surface, as though painted on with a spray can, lunar swirls are beautiful yet mysterious phenomena that humans have pondered for centuries. Reiner Gamma, the most famous of the lunar swirls, can be seen by the average astronomer with a basic backyard telescope. Yet we still don’t know what exactly are lunar swirls and how do they form? Well, an upcoming lunar mission may help shed some light on this very question. Lunar Vertex is set to be the first investigation in NASA’s Payload and Research Investigations on the Surface of the Moon, or PRISM for short. Lunar Vertex is set to be delivered to the Moon aboard a robotic lander that was recently selected through NASA’s Commercial Lunar Payload Services program, or CLPS, and will explore the mysterious swirl feature of Reiner Gamma to better understand this phenomenon, and that’s set to happen in just a few short years. Today, we’re joined by principal investigator for Lunar Vertex, who’s at the John[s] Hopkins University Applied Physics Laboratory, or APL, Dr. David Blewett. He will be enlightening us about lunar swirls, the associated magnetic anomalies, and how the Lunar Vertex mission may help answer key questions that scientists have had for hundreds of years. With that, let’s get right into the podcast. Enjoy.
[Music]
Host: Dave Blewett, thank you so much for coming on Houston We Have a Podcast today.
Dave Blewett: Oh, thanks Gary. I really appreciate the invitation.
Host: This is a very interesting topic, lunar swirls, and of course the instrument on the, on the CLPS mission that’s going to be sending some fantastic instruments to, to learn more about this. But it’s, it’s a very interesting thing, there’s a lot of unknowns here, so, so we’re going to try our best to, to best understand it and I think you’re the right person to do it. You have a wonderful background, Dave. And, and honestly, part of it is, is me being jealous; I mean, not only your, your understanding of the cosmos, but you got to spend a significant amount of time in Hawaii as well. Can you tell me about, about your pursuit to, to lead you to where you are today, to, as the PI (principal investigator) for this Lunar Vertex, Vertex experiment?
Dave Blewett: Yeah, sure. Yes. I was, I was very fortunate, indeed, to attend graduate school at the University of Hawaii. And, you know, when I was there my thesis advisor, Dr. B. Ray Hawke, and one of the other committee members, a guy named Jeffrey Bell, they had made observations of the Reiner Gamma swirl from Mauna Kea Observatory and published a paper about it some years before I arrived as a student. And then, Jeff Bell shared some unpublished work that he did trying to identify possible swirls on the planet Mercury using the rather poor-quality images from the Mariner 10 spacecraft that, you know, visited Mercury in the mid-1970s. So, skipping around a little bit here but, when I joined the science team for the MESSENGER (Mercury Surface, Space Environment, Geochemistry and Ranging) Mercury orbiter mission in 2007 I, I was pretty keen to follow up on the idea of swirls on Mercury. And it, it turned out that there aren’t any, although MESSENGER made a whole boatload of really amazing discoveries about, you know, the innermost planet, but that’s for a whole another, a whole another podcast. So, so I’ll go back to the Moon.
Host: Yeah.
Dave Blewett: Yeah. So, you know, I, this interest was piqued because of this work that my, you know, committee members had done. And so over the years I, and, and some of my other colleagues who are interested in this topic, we, we kept advocating for the really cool science opportunities that, that these special places have to offer. And we had done some conceptual work for a higher-priced mission to Reiner Gamma. So when NASA announced that Reiner Gamma was going to be the destination for the first PRISM mission, we were in pretty good shape. You know, we had much of the science team together, we had a good idea of what instruments we would propose. And so, we were just very fortunate that our proposal came out on top in the review process, and so here I am.
Host: That is fantastic. That’s fantastic. It seems like you, you, you had a lot of experience to get you to a point where, by the time this opportunity presented itself, that there was a mission that’s going to go to this very interesting place, and we’ll, and we’ll get into Reiner Gamma, and why that’s very interesting when it comes to, to lunar swirls, but can you tell me about some of the, some of your research and, and some of your pursuit through, through your education and then where you ultimately ended up at, John[s] Hopkins Applied Physics Laboratory that, that really led you to investigating lunar swirls in particular?
Dave Blewett: Yeah, so I have a, a bachelor’s degree in astronomy and astrophysics. I went to the University of Pennsylvania. And I, my master’s and Ph.D. are from the University of Hawaii in geology and geophysics. I worked with the, the planetary, planetary group there in the Hawaii Institute of Geophysics and Planetology. So I, I studied the Moon for my, for my Ph.D. We did observing at Mauna Kea Observatory. And then I was fortunate to, for my Ph.D., to work on data from the Clementine lunar orbiter, which flew in 1994. And that was the first time that we had a global, multispectral — that means images taken in different colors that can provide compositional information — we had a, a global digital image, images of, of the Moon, right? Before that there was pretty much only the, the old, essentially analog data from the lunar orbiters and from Apollo. So I, I worked on some, you know, geological problems using that Clementine data and some algorithm development for determining composition of the surface. So that, that was very exciting, I was happy to do that. But after graduate school, I, I wanted to stay in Hawaii for a while, and I actually went to work for a small tech company that was doing applications of the, the same kinds of remote sensing that we do for the planets, but on problems here on, on Earth, either, kind of military airborne sensing, I worked on a, a cancer detection project, so all kinds of cool stuff. I did continue to, to do some NASA-funded lunar research at a pretty low level. But then I had the opportunity to, to move to APL, and that was 15 years ago, by now. And I guess being a, a true space cadet at heart, you know, the opportunity to come and join the planetary exploration group here in the space exploration sector at the Applied Physics Lab, you know, was, was more of allure than, than the call of the islands.
Host: Very good. Now, now you’ve, your fascination with, with, you know, all of the celestial bodies that are in, in space right now is, is very apparent. Lunar swirls are an interesting one. From what we could tell, there’s very little that it seems that we understand about lunar swirls. It sounds like scientists have some idea, but, but it is a very interesting topic. For our listeners, can you help us to, to introduce us to what lunar swirls are?
Dave Blewett: Oh yeah. So they’re, they’re a really longstanding puzzle in, in lunar science. So Reiner Gamma is this, the most famous of the Lunar swirls. It, it’s on the Moon’s near side, right, and so it was seen by some of the earliest telescopic observers, you know, hundreds of years ago. And at first people thought in those blurry ancient telescopes, you know, they thought it was a, a crater. And it was actually given the name Galilaei, you know, for, for Galileo. But later as, you know, telescopes improved and eventually photography became available, people realized that that thing isn’t a crater, and it isn’t a ray of ejecta from a crater; it’s not a ridge, it doesn’t cast a shadow, so it must be a very thin surficial marking. And it was renamed Reiner Gamma, for the nearby Reiner impact crater. And it’s a, a curving bright pattern that extends for a couple hundred miles across the surface. And there are thin, what people have come to start calling dark lanes, that are interspersed within this sinuous brighter marking. And then, OK, you know, once we got to the Space Age there were images collected by the, the lunar orbiters that preceded Apollo, and then by Apollo itself, the astronauts and the, you know, metric cameras that were in the command modules. And people found other examples of features like Reiner Gamma. Most of them happen to be on the far side of the Moon, and what’s interesting is some of those far side swirls are on highland terrain, right? Reiner Gamma is on Oceanus Procellarum, right, one of the big, dark, relatively smooth lava planes, right — Latin, in Latin, the, the plural is maria, right — on the near side. On the far side there are swirls both on these maresurfaces and on the rugged, brighter highlands. So people started to recognize there’s this, there’s this class of, of feature, but, you know, well, what are they? How are, they’re, they’re, they’re quite beautiful, they’re mysterious; how do they form? Well, there’s a number of ideas that people have had over the years. One of the earliest was that the surface had been actually scoured by gas and dust in the coma of a comet that collided with the Moon. That idea was published in 1980 by a, a researcher named Peter Schultz at, at Brown University. Now there’s a couple other major hypotheses for the swirls, but they have to do with another discovery about swirls that came from Apollo and, later on, the Lunar Prospector robotic orbiter. And that discovery is that the Moon has localized patches of magnetic rocks and they happen to coincide with the swirls. So, these magnetic anomalies are something else that we should talk about.
Host: Yeah, yeah, we should. What is that? A magnetic anomaly?
Dave Blewett: Well, you know, it turns out that the Moon doesn’t have a global, internally-generated dynamo field, like say, the Earth and Mercury. But there are regions where there are magnetized crustal rocks, and we, these are called magnetic anomalies. So this is a, a second mystery, OK: why are there magnetic areas on a planetary body that today doesn’t have a global field? Well, just like with the swirls, there are a number of hypotheses for the formation of the magnetic anomalies. But now that we know about the magnetic anomalies, let me head back to some of those other ideas for how the swirls may have formed…
Host: Yeah, sure.
Dave Blewett:…and then we’ll, we’ll tie this all back in, I can say some more about the magnetic anomalies in, in a couple minutes. All right. So, how did this swirls form? OK, one idea is scouring by the, the coma of a comet. Well, another hypothesis is called solar wind shielding. And the concept here is that this local magnetic field acts as kind of an umbrella, right, that protects the surface from the charged solar wind particles, mostly protons and electrons that stream out through the solar system from the Sun. Now in a normal non-magnetic area, these solar wind particles come straight in and hit the surface, since the Moon has essentially no atmosphere. And it’s thought that the, the protons in particular effect the rocks and the soils and cause them to darken over time. This process, it’s called space weathering, and the darkening happens when ferrous iron — if you remember your chemistry, that’s Fe2+ — ferrous iron in the silicate minerals gets chemically reduced to its metallic form. And so there are these tiny iron particles, and they’re very good at absorbing light. So the material becomes darker. Well, so think what ha, might happen if part of the surface is shielded from the solar wind, right? That area might remain bright while nearby locations that don’t have a magnetic field, they kind of darken as usual. And if the structure of the magnetic field is very complicated, then the result could be the complicated sinuous pattern of bright and dark that we see in the swirls. So this idea, the solar wind shielding hypothesis, was also published in 1980 — 1980 was a banner year for, for lunar swirls — and the first author of that paper was Lon Hood of the University of Arizona. And it’s really cool, we’ve got him as a team member on, our Lunar Vertex mission. And I’ll just remember, mention one other idea for what the swirls, you know, how they could be forming. And this has to do with the unusual behavior of electrostatically-levitated dust. All right. So there’s, there’s pretty good evidence that solar ultraviolet light causes tiny little dust grains to become electrically charged. And repulsive forces might cause these grains to hop around. Now, through kind of complicated means in an area where there’s a magnetic field, there could be some associated electrical fields that are set up. And therefore these electrical fields could influence the way that these little charged dust grains are hopping around, and maybe they get attracted to or repelled from certain locations that causes an accumulation of dust. And maybe this bright dust is what we’re seeing as, as the swirl. So that idea is modern, it was proposed in a 2011 paper by Ian Garrick-Bethell, who’s now at the University of California Santa Cruz. So those are pretty much the leading ideas for how the swirls formed. And then if you like I could say a little bit about, how did we get the magnetic anomalies.
Host: Yeah. That’s exactly where I was going to go because you said you were going to circle back to that, so let’s, so let’s, yeah, let’s explore that for a bit.
Dave Blewett: OK. Yeah. So this, we’ve got our second mystery now, right: how, what formed the magnetic anomalies? Well, just to sketch those out really briefly. So first, remember I mentioned the comet impact mechanism for producing the swirl? Well, that idea actually wants to make the magnetic anomaly at the same time, and this is proposed to occur when there are complicated interactions that take place as the comet’s coma, the plasma in this coma. is compressed against the Moon, and there could be amplification of the comet’s magnetic field or any ambient fields. And the idea is that it ends up impressing a magnetic field on the surface materials. So that’s one. Now, another concept is also related to impacts, but in this case it’s the formation of large craters. You know, planetary geologists, when there’s an impact crater that’s bigger than maybe a couple hundred kilometers in diameter, we call it a basin. So basin-forming impacts are just tremendously energetic events, and there are gigantic quantities of melt and vapor that are produced. And perhaps the plasma that is created in such an impact, it could expand across the Moon and around the Moon and converge on the point antipodal to the impact, right? That’s the point, you know, diametrically opposite.
Host: Opposite.
Dave Blewett: Yeah. And so, that converging plasma, again, could perhaps amplify any ambient fields and cause the molten ejecta from the impact to acquire a magnetic field. All right. And then the third idea for making the magnetic anomalies is that, well, maybe in the distant past the Moon did have an internal dynamo field that it was generating in its small metallic core, you know, just like, you know, the Earth does today. So any lavas that erupted onto the surface or magma bodies, you know, within the lunar crust, they might cool in the presence of that global field and retain what’s called a remnant magnetic signature. But the global field has since died out. So, we, we don’t, we don’t see it today. Yeah, so all these different ideas about the swirls, all the different ideas about the magnetic anomalies, they make certain predictions about, you know, the physical nature of these things. And our mission is, is designed to make observations that will allow us to test those hypotheses.
Host: Yeah, this is multi-tiered here, right? You got, you got some ideas about, the, the lunar swirls and then, and then the magnetic anomalies. I was, I was trying to write down all the, all the different magnetic anomalies and see if I could, if I could keep up. And from what I could gather that first one was more like, it was almost like it was delivered from the comets. Sounds like the second one — more of the, sorry, sorry, say it again.
Dave Blewett: Yes. That’s the, the comet impact producing the, the magnetic anomaly that’s right.
Host: Yeah. Yeah. And then the other one was the impact itself converging, almost on a global scale, as the, from, from the, from some of the larger impacts, and then the other one moreso from the Moon itself than, than from, than from comets.
Dave Blewett: Yes. Mm-hmm
Host: OK. That’s OK. Very good. So, so there’s a lot that, and, and that’s the idea here, I think, is that there’s a lot of, you’re making observations, you’re collecting data and, and you have some, some ongoing theories but, but, and this is what we established sort of in the beginning was, we really don’t know. We, we have some ideas: maybe it’s, maybe it’s one, maybe it’s a mix of some of them, and that’s where I think this mission comes in, right? So this is a, you said you were excited about this opportunity because Reiner Gamma is, is, one example of the swirl, and I think, you can correct me if I’m wrong, I think one of the reasons this particular swirl is so famous, I think, is because it’s the largest and most observable, and if you had a telescope in your backyard it’s something that you could, you could observe yourself. That’s, is that am I characterizing that right?
Dave Blewett: Oh yeah. There are some pretty spectacular swirls on the far side, but of course, we can’t see them from telescopes on the Earth. But yeah, Reiner Gamma is definitely visible to, to amateur astronomers.
Host: Fantastic.
Dave Blewett: And we look forward to, you know, maybe having some star parties and that sort of thing associated once our mission’s going.
Host: [Laughter] Well then, well, let’s get right into the party then, let’s talk about the mission. Lunar Vertex. Now this, you obviously have some, some, some ideas about, and some hypotheses that have been around, as you mentioned, some of the, some of the first theories about lunar swirls were published in 1980 though they were observed early, earlier than that. So, so you’ve been thinking about this a while. This is something where we actually get to physically go to that fantastic location, Reiner Gamma. So what is Lunar Vertex? Tell us about this mission.
Dave Blewett: Right. So Lunar Vertex is the first of the so-called PRISM missions. That’s, that’s an acronym that stands for Payloads and Research Investigations on the Surface of the Moon; P-R-I-S-M, PRISM. And what this program is doing it is allowing, it, it’s funding science investigations that will be carried to the surface of the Moon onboard commercial landers. So that’s a, another new, relatively new program that, that NASA has, that goes by the name CLPS, Commercial Lunar Payload Services. And the way that CLPS works is that there are a number of companies that have qualified to bid on these delivery jobs. And the, the, the CLPS companies are in charge of, of all aspects of the mission, essentially: they, they build the lunar lander, they have to go out and contract with a, a launch vehicle provider – -you know, that means a rocket to get you to the Moon — they are in, responsible for the communications between the, the Earth and the Moon. And they just, they just bid on these jobs when, when NASA issues a, a call for, for proposals. So it’s a new way of, of doing business, right, and the idea is to, to foster the, the commercial space industry and in particular, you know, for, for lunar lander services. And then, you know, for me, it’s, it’s this great opportunity to have more frequent and low-cost access for, for science payloads to get to the Moon.
Host: Fantastic. And so, what’s the, what’s the commercial vehicle that you’re working with now that’s going to transport all the instruments that you need for, for this experiment?
Dave Blewett: Yeah. So that’s an interesting question, because, you know, in a typical planetary or space science mission the spacecraft and the instruments kind of are designed together to meet the science goals. It’s, you know, every spacecraft is more or less a, a custom, custom job, right? But here, we’ve got these companies that have their essentially stock lander, and they will make some modest modifications to accommodate, you know, in, in this case, my payload suite. But it, it’s not a, a completely bespoke spacecraft. So, and in fact the, the, the lander is selected after our Lunar Vertex science investigation was chosen. So, yeah, so it’s, it’s, it’s, again, it’s, it’s a new way of doing things, you know, everything isn’t exactly perfect, we don’t have full control over the design of the lander, but, you know, we’re working with our provider, it’s a company called Intuitive Machines that NASA selected for our delivery. And we’re working really well with them to, you know, let us have a, a successful science mission.
Host: And so, what is that mission? So it’s, it, you got, you got the delivery vehicle, obviously, and it sounds like you were selected a while ago. What is, what is this pay, now, that’s what we’re talking about, this Intuitive Machines, that, that’s the actual delivery truck, right, that’s going to, that’s going to land on, on the Moon, but then obviously there’s that, and that delivers your payload of sorts; so what is your payload? What is, what is this instrument that’s going to help observe lunar swirls? What does this look like?
Dave Blewett: Yeah, right. So you, you you’re, you’re just right. There’s the, there’s the, you know, the delivery service provided by the lander but our Lunar Vertex payload suite, you know, it’s designed to carry out a, a comprehensive study of the Reiner Gamma magnetic anomaly and swirl. So we have three science instruments that are mounted on the lander, plus we have a small rover that’s going to carry two additional instruments. So the lander instruments, first up, we’re going to the most famous magnetic anomaly so you can bet we got a magnetometer, OK? Yep. And also on the lander there’s a set of cameras to survey the surroundings and measure the reflectance and how it changes as the solar illumination angle changes throughout the day. And we have a solar wind spectrometer, and what it does it, it detects the energy and direction of the ions and electrons that actually reach, make it down to the surface. And then we’ve got a small rover. It’s just about 20 inches long. It has another magnetometer so that we can find out how much the strength and direction of the magnetic field varies with position on the surface. Now we plan for the rover to drive about 500 meters, you know, three tenths of a mile, although we hope it can probably do, do twice that. And then the second instrument on the little rover is a special microscope, and it’s going to peer down at the soil underneath the rover’s belly and take close up pictures that show us the texture and the size of the particles in the soil. And, by using a set of different wavelength LEDs (light-emitting diodes) to illuminate the surface, the microscope will provide some information on the composition of the soil. Now, one of the key reasons we, we wanted to have a rover is that, you know, this information on the texture and composition of the soil, that’s going to help us to test these hypotheses for the origin of the swirls, right? If you remember, you know, oh, the, the comet coma collision involves this idea that sort of a wind of gas and dust scoured the surface; well, in that case, you might expect the, all the fine grain material to have blown away, right? But what if swirls are being formed by this dust accumulation hypothesis? Well, and therefore, you might expect there to be an abundance or overabundance of very fine grain dust, right? So it’s the, this microscope’s important, but, you know, the blast from the lander rocket engines is going to disturb the natural surface, so with the rover we can drive outside that blast zone so we can check out the pristine, unmodified surface material.
Host: Hmm. OK. All right. It’s multi-tiered here. So you got, you got the, you got, you’re observing the soil itself; now, now the magnetometer, let’s go to that for a second, because this one seems like it’s, you said, of course we have it, you know, and, and it’s, this is, we’re talking about magnetic anomalies, it, it measures, it measures this mag, magnetic anomaly. Now you have one on the lander and you have one on the rover. So what’s, what exactly are they going to be doing: is it, is it a redundant thing or do they have distinct missions?
Dave Blewett: Yeah, they, they have distinct missions. We’re actually going to have the lander magnetometer turned on during descent and landing because that kind of altitude profile, you know, from a hundred kilometers above the surface all the way down to, to landing, that’s really important for helping us to understand and, and produce mathematical models of the nature of the magnetized source body, as it were. So that’s really key, that we’re going to be on with the lander mag during landing, but then it’s just going to stay on after landing. And it has a, a special design that allows us to separate the, any magnetic fields that are generated on the lander itself from the natural background magnetism, which is what we actually want, want to measure, right? Because again, we don’t have full control over, you know, the design of the spacecraft ;you know, there’s, there’s, there’s something in, in, spacecraft engineering lingo called magnetic cleanliness, and we, we’re able to, to, request that the lander provider, you know, meets certain requirements, but, you know, again, it’s not like we can design the spacecraft from, from the bottom up to, to be super-magnetically clean. So we’ve got a special magnetometer that, that will be able to, to deal with that. And then, yeah, the little rover, like I said, is going to trundle around and enable us to measure the magnetic field at, at a variety of locations so that we can see how much does the, does the field vary. You know, is it like kind of uniform over this whole area, or is it, you know, radically switching back and forth, from, from point to point, which will tell us something about, you know, the nature of the source body, and then again the nature of how, the, the magnetism, what formed the magnetic anomaly there in the first place, you know, choosing among our hypotheses.
Host: OK. OK. So is, I mean, is, is one of your goals here to sort of narrow down the plausibility of each of these hypotheses? It sounds like, particularly the one that measures soil, right, you already mentioned that you’re, there’s, there’s two models that, if you measure the soil that you can, you can narrow it down better, but it sounds like this is sort of a big deal when it comes to better understanding lunar swirls, that this mission can be comprehensive enough to help the scientific community…I, I hope this is not too far of elite a leap, but really narrow down what’s causing these lunar swirls.
Dave Blewett: Yes, that’s right. We have sort of what, what we call a truth table, you know, where we, we list each of the hypotheses and sort of, you know, maybe down, down the left side of the table and across the top of the table, you say, OK, soil texture: fine or coarse; and then, you know, magnetic field orientation: you know, highly uniform or highly variable over short distances. And you kind of, you know, check off, you know, which, which hypothesis is being tested and which one, the predictions of which, which one are, are coming true. Although, of course, you know, the whole thing, it could be something we haven’t thought of yet, you know? I mean it, it’s not necessarily so that the, the, the hypotheses that people have so far are the correct ones. So, you know, that’s, that’s the excitement of, of scientific exploration.
Host: Yes. It’s about learning. Absolutely. Now how, how long do you think, would be sort of your mission requirement, right? You talked about sounds like there’s, there’s a period of observation, particularly with the Sun, right, where the angle of the Sun is going to matter, so you can collect data through, through different time periods. About, about how long is, is your goal here to, to sit on the surface and, and collect data, as much data as possible?
Dave Blewett: Yes. These early commercial landers are not required to survive the lunar night. So the, the plan is for the lander to touch down in the morning at the site. The Sun will be about ten degrees above the horizon, and these are solar-powered landers so, you know, the Sun will, will rise and transit across, you know, the noon time, local, local time there at Reiner Gamma, and so the mission will end late in the afternoon as the Sun gets low in the western sky. So this is, you know, essentially, one lunar daytime period or, or half a month. Actually, we think it’ll be about 13 days, our, our surface mission.
Host: Thirteen days, really driven by the solar power that enables you to power your instruments.
Dave Blewett: That’s right. Yep. It’s going to be a, a frantic 13 days.
Host: I bet, right? Or, you got to make sure everything works, and so, so let’s go into the engineering challenges here. Let’s, let’s start with the lander for a second. Sounds like you got a couple of instruments on there: magnetometer, you got some cameras, you’re measuring solar winds. Now, are, are you, here’s a, here’s a question: are you the only payload that has to, that’s part of this delivery service, or are you going to be sharing some space on this lander?
Dave Blewett: Right. That is, is very good point. NASA allocated a certain amount of mass to Lunar Vertex, and power, but they also have kind of a list of experiments that they want to send to the Moon, and so, they filled out the, sort of the remainder of the manifest with a couple other, three other things. One is a technology demonstration from the Jet Propulsion Lab[oratory] that involves a cooperative activity among some small rovers. There’s one from the European Space Agency that is a laser retroreflector. And then there is an experiment from South Korea that is an energetic particle detector. So those are all other things that will, will be on the lander.
Host: And so, you got to share that space, right? So do you, when, when you’re talking about these instruments, do you have requirements that you have to, you know, when you’re designing the, the instruments, they have to be of a certain size, or they have to play nice with the, with the lunar lander and some of these other instruments that you’re talking about that are onboard? What are some of the engineering challenges when it comes to designing some of these?
Dave Blewett: Yeah, well, well that accommodation is, is mostly up to the lander provider, but you’re right, everybody, all the payloads, have a kind of, you know, “do no harm” clause, right? And the project scientist in the NASA planetary mission program office has had a few kind of “meet and greets” among the, the different payload teams that are going to be on this particular CLPS lander. So, you know, everybody wants everybody else to be successful, and I, I, I think, you know, there’s going to be some opportunities for sharing data and, and that sort of thing. There, there’ll be really, really helpful.
Host: Oh, fantastic. When it comes to the rover itself, what are some of the engineering challenges there? When it comes to size, when it comes to tire design and your anticipation of the soil that it’s going to interact with, what are some of the engineering challenges when it comes to the, the rover that you’re designing with those instruments?
Dave Blewett: Yeah. So we’re getting our rover from a company in Golden, Colorado; it’s called Lunar Outpost. So this is the business that they’ve gone into and they’re going to be flying at least one other rover before the Lunar Vertex rover. So they will have had some practice on driving and navigating on the Moon and that sort of thing. But you, you can imagine that with this, this is a small rover, right, we have a small budget, we can’t, we can’t buy some gigantic car-sized, dune buggy. We’ve got this little guy and it, it needs to maintain communications with the lander, line of sight radio link. So, fortunately the, the place we want to go, Reiner Gamma. is out in these very flat lava planes, and we have great topographic maps that have been constructed from Lunar Reconnaissance Orbiter images. And using those, we’ve been able to create something that is called a viewshed map. So, the way that works is if, imagine the lander is at, is at a certain point and the antenna is say, three meters above the ground; well, then you can show on a map every point that has line of sight to that antenna. And so that’s how we’re helping to, or, starting to plan out our traverse is by finding a path that will allow us to maintain that line-of-sight comms back to the lander, because we’re, you know, the, the guys from Lunar Outpost are, are going to be driving the, the rover in real time.
Host: Oh, very cool. So Lunar Reconnaissance Orbiter has been pretty helpful in, in the design of this mission, it sounds like.
Dave Blewett: Oh yeah. I mean, for anything that happens on the Moon these days, you know, we pretty much have LRO, Lunar Reconnaissance Orbiter, to thank. You know, LRO has been in orbit since 2009. It’s, it’s collected a, amazing set of, of images. I mean, petabytes, I think, of, of data, the largest planetary data set ever, ever collected. And that has allowed just so many fascinating new studies of the Moon. There’s the laser altimeter that’s been producing per, you know, amazing shape models of the Moon, which, which are needed — and, and, you know, gravity also — which, which are needed in order to allow these landers, and eventually the human landers, to, to, you know, navigate and to hit their pinpoint landing locations. Also, on LRO there’s a, an instrument called Diviner: it’s a thermal infrared radiometer, and that, the data from that instrument tells us about the thermophysical properties of the surface: rock abundance, kind of a porosity and so forth, in addition to composition of the surface. So, data from data from, from LRO has, has shed some new light on, on the swirls themselves, and it, it’s just so I, important for, from an exploration standpoint, allowing, allowing these missions to, to take place.
Host: Wonderful, wonderful. It’s, it is very exciting time for, for Lunar Vertex, sounds like…is very exciting, sounds like, for your team as well. Can, can I ask about the name, Lunar Vertex? Why, why, why did you choose, choose that?
Dave Blewett: Yeah. So…we, you know, I was writing the proposal and the first name we had was an acronym: mag, magnetic anomaly PRISM suite – m-a-p-s, MAPS. But that, that wasn’t completely satisfactory to me. It, it’s an acronym that’s got an acronym inside it, you know? [Laughter] And so, I was, I was kind of casting around for, for a better name and I decided to go to an online translator and look for the word “swirl” in various languages. And for a long time I didn’t find a word that was kind of, you know, melodious or, or sounded good for the name of a mission, until I tried Latin. So in Latin, “swirl” can be translated as vertex, kind of like a vortex or a whirlpool. All right. So I thought that sounded pretty good. Plus, you know, in, in English, a vertex is, is an intersection, right, where two lines meet. And so, I kind of envisioned it as a, as a, as a crossroads because our mission brings together planetary geology and surface processes, you know, things like the formation of the swirls, it, it brings that together with what’s called space physics. There’s particles and fields domain, of, of magnetic fields and, and the solar wind and so forth. So it, it’s not always that the, the geoscience and the space physics communities intersect, but they, they do come together in a lunar magnetic anomaly. So that, that name, Lunar Vertex, it’s really a symbol of the interdisciplinary nature of our mission.
Host: Wonderful description, absolutely. And, and the Lunar Vertex team has been working hard. Can you, can you tell me about where you, where you guys are at this point? We’re in, we’re recording this late May 2022, I’m sure you guys are excited for, for, you know, as we get closer to actually landing on the Moon; still, still got some time, but can you talk about where you are today?
Dave Blewett: Yeah. The, the launch is scheduled for April of 2024. Just a few weeks ago we held our PDR, preliminary design review. And we, we passed that. There was a, a panel of, NASA reviewers who listened to our, our presentations about every aspect of the mission, and they said we’re doing great. Of course, they did have some suggestions and requests for action and so forth, and our technical team is in the process of preparing responses to those. But that was the, essentially, the major continuation review for, for the project. So, you know, pretty soon we’ll be able to, we’ll be given the go ahead to, to start, you know, building flight instruments and, and, and so forth.
Host: OK. Yeah. And then all the testing begins so, a long, a long road ahead, but when you pull back and, and think, and think about what, what you’re doing, and, and, you know, you, you’re, there’s this crazy idea of a lunar swirl that has, that scientists have been hypothesizing for a while, and you’re getting this opportunity to, to go to Reiner Gamma and like physically be there with, with all sorts of instruments that I believe scientists may have been wanting for, for a very long, long time, to, to, to get to this point. When, when you think about that you’re on the team and, and, and, and have this opportunity that’s been enabled through, you know, things like PRISM and CLPS, like, what, what are sorts of the emotions that, that come to mind, that say, wow, we’re, I mean, this, this is only a few short years away, we’re, we’re really, really close.
Dave Blewett: Yeah. That, that, that’s right. You know, I, I’m old enough to remember the, the Apollo missions. And when I was just four years old my parents sat me in front of a black and white TV to watch those snowy pictures of the Apollo 11 astronauts. And I happened to grow up to be a lunar and planetary scientist, and I have been interested in the science of lunar swirls and magnetic anomalies since grad school. So, you know, the fact that I’m here now leading a lander and rover mission to explore, you know, what I would argue is the most beautiful and mysterious feature on the Moon, well, that’s, that’s just indescribable.
Host: I bet. That’s, that, it’s, it is, it is beautiful, you know, some of the, some of the photos, I mean, some of the, the photos are a little bit, that I’ve seen are, are, are black and white, but it is, it is this crazy phenomenon and it’s so, it’s so cool to think how close we are. Besides, aside from the fact that, you know, there’s these theories that have hypothesized where lunar swirls come from that, and these, and Lunar Vertex may help answer some of those. How, how do you think this mission, just overall, will help us to understand just more about planets and, and their formation and about the history of our solar system going beyond just, just the, these, this phenomenon itself? How, how, how, how do you think what we learn can be applied to a much broader understanding of, of our universe?
Dave Blewett: Yeah, I think there’s, there’s some very good ways that it can be applied. I mentioned that soil-darkening process that happens; we, we, we call that space weathering, and that’s something that affects the surfaces of airless bodies throughout the solar system. So, Mercury, the Moon, asteroids, the moons of the outer planets. And when we observe those bodies with remote sensing, you know, whether it’s with an Earth-based telescope or with a instrument on a spacecraft, the, the space weathering kind of complicates our interpretations, right? So, you know, if we see a surface that looks dark, well, is it dark because those rocks are inherently low reflectance because of their composition, or is the surface dark because of this space weathering, right? So it’s, it’s important to understand this as well as we can. And, now a great thing about studying space weathering in a lunar swirl is that it’s a natural laboratory. So a, a little while ago, I mentioned how the, the solar wind is thought to contribute to this space weathering; well, there’s another agent that also affects these airless body surfaces and that’s micrometeoroid bombardment. So, sand and dust-size particles that just come zinging in with their full-on cosmic velocities and hit the surface, and they cause melting and vaporization. Now, it’s not known which of these two space weathering agents, the solar wind versus the micrometeoroids, which one really dominates this, this darkening. But in a swirl, the magnetic field attenuates the solar wind, but it doesn’t affect the trajectory of micrometeoroids. So it’s a perfect opportunity to do an experiment with a control, right: we can examine space weathering with normal micrometeoroid flux, but there’s this decreased solar wind. So it’s just like, nature’s just presenting us with a fabulous natural laboratory to conduct such an experiment. And, you know, the magnetic field part, you know, learning more about the Moon’s magnetic fields, that’s important for understanding its thermal history. You know, how long was it hot enough down in the core for there to be convection of that molten iron generating a magnetic field? You know, and internal heat is related to vulcanism, so for how long was there melting in the mantle, you know, driving magmas towards the surface and maybe eruptions? Now, you know, I mentioned all those hypotheses for the magnetic anomalies, but you know, what, if it turns out that we think the magnetic anomalies were produced by impact processes? Well, that’s an important, you know, discovery if we can, you know, confirm that in fact, asteroid or comet impacts can produce magnetized rocks, you know, that’s, that’s pretty interesting and, and important. And again, something that could be happening on other bodies in the solar system. And one other, kind of the third major goal of Lunar Vertex is to look at the interaction between the solar wind and the local magnetic field. So there’s evidence from orbital studies that in some locations the magnetic field is actually strong enough to stand off the solar wind. And this creates what the plasma physicists call a mini-magnetosphere. Now these are probably the very tiniest magnetospheres in the solar system. You know, they’re much, much smaller than the, the big magnetospheres of Earth or Mercury, or certainly of the, you know, outer giant planets. But nonetheless, you know, there’s interesting plasma physics going on. So Lunar Vertex is going to help explore this full range of, you know, diversity of magnetic, magnetospheres in the solar system.
Host: Very exciting stuff. Now, I think, you know, many of our listeners there, there may be some who, who got to have the, the extreme pleasure that, that you did of, of witnessing the Apollo missions themselves. But we’re in this new era of, of exploration with, with CLPS as, as the robotic missions, but Artemis is human missions and, and everything like that. I, I expect, I hope at least, a new wave of inspiration, just like, just like you had, where you saw, you saw something so wonderful and dedicated your career to, to exploring the cosmos. For those that are, for the next generation that, that want to follow in your footsteps and conduct science and continue this fantastic research of understanding our universe, what would you say to, to listeners who may be considering pursuing, you know, science and, and astronomy or, or geology, any of the things that, that you’re, that you’re looking at, and, and want to take that next step into, into this wonderful world? What, what, what advice would you, would you pass on to our listeners?
Dave Blewett: Oh, well, this is just a fantastic time to be getting into, into the space biz. You know, whether you’re a, an engineer, a scientist, or any other contribution that, that everyone across our society makes to a, to a big endeavor like Artemis, you know, returning, returning to the Moon with, with humans and robots. It’s, it’s just, you know, so exciting that, that America is doing this. The Moon is a place with just such an incredible diversity of features. There’s, there’s so much to learn about the formation of the Earth-Moon system and planetary evolution in general. So, you know, whether it’s the water that’s frozen in the permanent darkness of the craters and the polar regions, longstanding mysteries like the lunar swirls, or, or more recently discovered features that came from LRO, — you know, pits, caves, lava tubes. There’s this, you know, dome-shaped volcanic mountains of a strange composition that are going to be the target for the PRISM 2 mission. You know, the Moon, it just has so much to offer. You know, the Apollo missions half a century ago, they were just a, an astounding first step. But now with, with Artemis we’re ready to go back in an even bigger way. We’re, we’re going to study the Moon from, from pole to pole and from near side to far side, you know, with both these low-cost robotic missions like PRISM all the way up to the establishment of a sustained human presence. So, I just think we’re very fortunate, you know, to live in a country that’s able to spend a tiny, tiny sliver of the federal budget on these kind of pursuits of the imagination, whether it’s basic science research or space exploration or the arts and humanities. I’m just very grateful for that. So, you know, I, I look forward to seeing everybody on the Moon at Reiner Gamma in two years.
Host: [Laughter] Wonderfully said. Dr. David Blewett, thank you so much for coming on Houston We Have a Podcast. This, this pursuit and, and Lunar Vertex is a, is a wonderful mission, very inspiring, and I hope our listeners will, will follow along to understand, you know, your progress through this and then ultimately what we find from some of the instruments you’re sending to the lunar surface. Thank you so much for coming, again.
Dave Blewett: Oh, you’re welcome, Gary. It was fun to talk with you.
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Host: Hey, thanks for sticking around. Fascinating stuff with Dr. David Blewett today. I was very pleased to have him on and learn so much about lunar swirls and this mission, Lunar Vertex, that is going to help us to answer key questions. This is part of the PRISM. NASA’s PRISM and NASA’s CLPS initiatives. That’s PRISM, P-R-I-S-M, and CLPS. C-L-P-S. You can check those programs out in the initiatives and stay up to date on the latest and greatest at NASA.gov. We are one of several podcasts that you can find here at NASA, at NASA.gov/podcasts. You can check out our full catalog of episodes at that website; just click on us, Houston We Have a Podcast, and you can listen to any of our episodes in no particular order. If you want to talk to us, we’re on the NASA Johnson Space Center pages of Facebook, Twitter, and Instagram; just use the hashtag #AskNASA on your favorite platform to submit an idea for the show, or maybe ask a question and just make sure to, to mention it’s for us at Houston We Have a Podcast. This episode was recorded on May 27th, 2022. Thanks to Alex Perryman, Pat Ryan, Heidi Lavelle, Belinda Pulido, Nilufar Ramji and Jayden Jennings. And of course, thanks again to Dr. David Blewett for coming on the show. Give us a rating and feedback on whatever platform you’re listening to us on and tell us what you think of our podcast. We’ll be back next week.