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 289, the Principal Investigator for NASA’s Lucy mission discusses the spacecraft’s 12-year journey to eight different asteroids as we look to better understand the formation of our solar system. This episode was recorded on April 21, 2023.

Transcript

Gary Jordan (Host): Houston, we have a podcast! Welcome to the official podcast of the NASA Johnson Space Center, Episode 289, “Lucy.” 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. But if you’ve been an active listener, you know that we don’t really stick to that all the time. We talk about Artemis a lot on this podcast and the number of benefits of sustained lunar exploration, of course, one of which is the science of the Moon, science which can help us to understand more about the solar system. The same with other missions we’ve covered on our podcast, like OSIRIS-REx, (Origins, Spectral Interpretation, Resource Identification, Security-Regolith Explorer) returning a sample from a carbonaceous asteroid to give us hints into learning about the formation of life in the universe. These are big questions that add to our understanding of the history of, well, everything. And scientists continue to come up with ideas for how to answer these big questions. One mission that launched in 2021 has an ambitious goal of learning about the formation of the solar system by visiting eight asteroids in 12 years. The mission is called Lucy, and you’re not going to believe this, it’s not an acronym, but it’s named Lucy for a fascinating reason, all the same and we’ll get into it in this episode. This year, Lucy visits the first asteroid and scientists are excited. So, to discuss the Lucy mission and the big questions that it can help us to answer ahead of this fascinating milestone, we’re bringing on the Principal Investigator, Hal Levison, from the Southwest Research Institute in Boulder, Colorado. All right, let’s get started. Enjoy.

[Music]

Host: Hal Levison, thank you so much for coming on Houston We Have a Podcast today.

Hal Levison: It’s my pleasure.

Host: It’s, it’s, I think it’s my pleasure, truly. You are the go-to guy when it comes to Lucy. Been doing, talking about Lucy quite a bit since it’s launched, before its launch. And if I’m not mistaken, Hal you’re going to be, are you going to be sticking around for quite some time, continuing to talk about Lucy through the mission?

Hal Levison: Yeah. The, it’s a 12-year mission…

Host: Yeah.

Hal Levison:…all told. The last encounter is in the day after my 74th birthday, March 2nd, 2033. And I plan to be here for the whole time.

Host: You know what, you can actually probably do a little bit of both; have the encounter and a 74th birthday party at the same time.

Hal Levison: I, we probably will.

Host:[Laughter] Very exciting stuff. While…

Hal Levison: Go ahead.

Host: I was going to say, how I’m very much looking forward to this and, and want to, and want to get to know you, get to know this mission a little bit better. I wonder just sort of what inspired you to, to get you to where you are? I mean, I know you’ve been with Lucy for quite some time, but, you know, this, this mission, Lucy, what we’re going to be talking about is, has this very grand ambition of, of a better understanding the beginning of our solar system. And I wonder, if perhaps you had some inspiration as, as a child or, or at some point in your life that, that set you on the course to get you where you are today?

Hal Levison: I took a very odd and circuitous route to this position. So if you actually go and look at my scientific record, I’m actually a Theorist, which makes me a very odd for Mission PI. I study the dynamics of the origin of the solar system, how we get planets like the Earth, how the small body populations, particular, inform us on the history of the solar system and the formation of the planets. That’s sort of been my specialty, oh, throughout my, the second, let’s say the second half of my career. And I think we, I realized a few years ago that we hit a point where I think we are in a situation where we’re idea-rich and data-poor. When I got into the field of planet formation 20 some odd years ago, right, we were in a situation where I think we were idea-poor and data-rich. In other words, we would look around the solar system and just see things that we just couldn’t understand, right? A famous problem from 20 years ago is why Mars is so small, right? And so, using that as an example, when I got in this field, we had no ideas of why Mars is smaller than the Earth. The planet formation theories would’ve predicted it was bigger than the Earth. And as you know, it’s 1/10 the mass of the Earth. Now, I think we have four or five different ideas of how the Mars could be so small, and yet we, you know, can’t decide because we don’t have enough data, right? And the same thing my specialty was comets in the outer solar system, a same kind of argument can be made in the outer solar system. When I got into the field, no one under knew had a good idea of how the Trojans formed, right? Now, I think we have some good ideas of how the Trojans got where they are at least, and we don’t know how to distinguish one idea from another. So I decided to go from being a Theorist, right, to getting more data that will help us answer some of these fundamental questions.

Host: I see, you, there was two, you, you were fulfilling the need, right? You, you wanted to, there were all these questions and that you wanted answers. So you thought you’d hop over to the data side of the house to, to go and fulfill those ideas that you had and try to, try to keep things moving.

Hal Levison: That’s right.

Host: All right.

Hal Levison: That’s exactly right.

Host: Well, then how did, tell, can, let’s start with Lucy, right away, and start talking about its origins and just sort of what, you know, you said you started as a Theorist and made your way this way. Can you talk about just sort of the early concepts, early ideas, early, early years, really of, of Lucy’s concept?

Hal Levison: Yeah. So, one of the things, so let me, I’m going to continue from where we were, our last question.

Host: Perfect.

Hal Levison: Right? One of the things that I’m curious about is the evolution of the outer solar system. When we worry about how planets like the Earth got here, one thing that we’ve learned over my time, my career was basically, if you don’t mind this pun, right? That planets like the Earth don’t form in a vacuum. They form as part of a system where materials that they’re growing from are being passed around by the growing planets. The growing planets are competing for those resources, right. And so, to understand how a planetary system that has an Earth formed, you have to understand the planetary system. And so, I focused mainly on the outer planetary system. We realized probably 15, 20 years ago that we have a problem making the giant planets where we see them. And so, the giant planets had to move around early in their history, right? I was one of the first modelers to actually sit down and try to understand how that could have happened? And one of the things that came out of these events moving the planets around, we found was that they formed the Trojans. So if you look at the Trojans from the ground, what you see is, although they occupy a very small region of space, they’re very physi-, they’re physically very different from one another. And you can see that in their spectrum, particularly their colors. And you can see objects that are gray, and you can see objects that are very red, which is indicative of coming from the outer solar system all sort of mixed together. And these ideas of how the planets moved around would predict that objects from all over the outer solar system could get mixed together and trapped in the Trojans during these events. If that’s true, right, then the different physical characteristics of the Trojans give us very important clues about how that mixing, and the planet migration process happened. So I realized that as a Theorist and, but what we didn’t really understand is what those colors are telling us about where and when the objects that we see in the Trojans formed. So really, the idea of Lucy grew out of this idea of trying to understand what the different colors are telling us about the chemistry of these objects. So we can link it to where in the protoplanetary disks they formed, and then that will inform us about how the planet migration process occurred. That was sort of my thinking when I started putting together Lucy.

Host: When, so, so you wanted to, you had this idea about the Trojans being sort of this, this, this area unexplored that has this capability because of where they are in the position of planet formation. They have this lovely, may-, maybe the right word here is preservation of the history of the solar system.

Hal Levison: Yes. Right?

Host: Yeah. Yeah.

Hal Levison: From my interest, the Trojans are special in that way, right? But really, I think, you know, if you look at the small body populations as a whole, right, they really do represent the, you know, we call them the fossils of planet formation, which is how we got the name Lucy, right?

Host: Right.

Hal Levison: These are objects that formed and were sculpted as the planets move, formed, and evolved, and they’ve been relatively pristine since then. So they really are a treasure of trove for understanding the history of the solar system. And that’s why NASA and the rest of the planetary community has spent so much effort studying these small bodies.

Host: A little bit more on Lucy, just that name. I know, it, it, it’s, it’s a wonderful name. And I know, I, I addressed this in, in the introduction, but funny enough, we always like to have acronyms, and this is not one of them, but, but Lucy in and of itself, being the fossil that, that you’re referencing, I love the way that it’s characterizing, you know, the, the, the, and comparing this particular fossil that was found on Earth with the idea of, and, and you, you, you stated it perfectly, this fossilize-, fossilization, the, the fossils of the, of the solar system. What exactly was Lucy and, and tying, tying more to why it’s, it’s such a perfect name for this?

Hal Levison: Well, Lucy is a well-known, think of it as the missing link. Back when I was a kid, right, in the 70s, there was really a link in our understanding the evolution of, of humanity. This is a fossil that lived roughly three million years ago. Boy, you’re pushing my knowledge here. This is not my expertise, right?

Host: [Laughter] I’m sorry…just high level

Hal Levison: Really represented the missing link between basically the ape-like creatures we were to the humans that we are.

Host: Yeah.

Hal Levison: One, one interesting fact about the name Lucy is that the Fossil was actually named after The Beatles song, “Lucy in the Sky With Diamonds.” And so, we have sort of adopted that as our theme song. I don’t know if you noticed our patch is shaped like a diamond.

Host: Oh my gosh. I totally missed that.

Hal Levison: And, and, yeah, and you know, we, every once in a while, we’ll refer to the Trojans as the diamonds in the sky because of what they’re going to teach us about the history of the solar system.

Host: You guys have to play that song when you’re, when you’re passing Dinkinesh here, up, up soon, right?

Hal Levison: If they’ll let us.

Host: [Laughter] Maybe not on air, so you don’t have to worry about the rights.

Hal Levison: Yes.

Host:Yeah. In terms of, you know, what we’re trying to find why the Trojans are interesting? You started thinking about Lucy, started thinking about concepts, right? You’re on the data side of the house now, you’re like, OK, I have this theory. How can I go find, how can I go figure out, you know, how to visit the Trojans, how to collect data? Is it true, one thing I found was the plan, one, I think, I think it was actually your words in an interview, was that the planets aligned for this mission, in terms of the, the concept and, and the opportunity that you had to visit the asteroids, how, how did the, truly the planets align for this to happen?

Hal Levison: So one of the keys, and I sort of mentioned this earlier, of the Trojans, in order to try to detangle, right, the history of the solar system, as I said, is the diversity. Is that they look around and they’re very different from one, right? And you can imagine taking that, if you knew what those colors were telling us about formation, then you can say this many Trojans came from this area in the solar system and this many Trojans came from this area in the solar system, and that helps us constrain the models, right? So the, the key, what I was thinking, the key when we were putting this mission together of trying to detangle all this stuff, is understanding the diversity and in order to understand the diversity, we have to visit enough objects that we can figure out what that diversity is telling us. So our goal when we started this, is to visit as many of these things as we can. OK. And that sort of makes sense just from an exploration point of view, because the first thing you want to do when you’re exploring a population is do a census and a reconnaissance and figure out the global picture. And then you can choose particularly interesting objects to go and visit in orbit and things like that. That’s been the whole history of, you know, the exploration of space. So all that sort of fit together, but we needed to visit a lot of objects. And we started off thinking that we could just get two and started putting together, a, a picture or a trajectory that would get us to two, one that’s very gray and one that’s very red. And then it all sort of was luck, right?… after that. So, the person, Brian Sutter, who’s at Lockheed Martin, a brilliant dude when it comes to this kind of mission planning, was showing us some movies just going to two of them, which are our first, everybody’s, and then the last in the L4 leading swarm, which is called Orus. And he just let the movie run, run for a while after showing us that trajectory because he’s worried about planetary protection, right? That we don’t hit something.

Host: Right?

Hal Levison: So he had this long movie and we’re sitting there talking after this, and he had some famous asteroids on his movie, and I noticed that it was flying by, it looked like the spacecraft may have been flying by Patroclus. And I asked him, well, can we go there? And he went and looked and gave early, we could go there, right? And, and so, now we had ever betters orbit, Orus and Patroclus, and it turns out that when he looked in detail, we could get to two more. And, you know, it turns out that that was very lucky. We did an experiment where, you know, because you have to propose these things to NASA, and one of the things that NASA cares about is timeliness, right? And, you know, why do we do it now? Why can’t we wait a decade until our technology is better, for example? And so, as part of our argument, we did an experiment and asked ourselves, well, what happens if we would — launch in like 2030, and we did the same kind of thing we tried to do from a launch date of 2021, and it turns out we could get to three. And they weren’t anywhere near as interesting, because each of those targets I mentioned are interesting targets for a spacecraft in and of themselves. So we have this extremely rich trajectory, and as far as we can tell, it’s just luck. Another way to think about it is, you know, I said that I studied planet formation. I’m a dynamicist, I worry about things, how things move around the solar system. That was my science. So I’ve been sort of, I’ve been sort of worshiping at defeat of the celestial mechanics gods for 30 years, and they’re paying us back, right? This is really, we weren’t doing this now, we would not be able to get anything anywhere near as interesting in the future. So.

Host: Very, very wonderful timing, honestly. And, you know, it must have been a really exciting moment where after all this hard work of, you know, putting your concepts together and realizing like, hey, now’s the time, pitching it to NASA. It must have been really rewarding when NASA accepted the proposal.

Hal Levison: Yeah. I remember the, the day of the announcement, and I was talking to a friend of mine, and I said to him, you know, no matter what happens today, I’m going to say, “oh, crap” now what do I do?

Host:[Laughter] And I guess, you know, it was kind of in a, in a, maybe in a good way, it was an, good, “oh, crap” because now you really had to kick into gear and start gathering a team to make this a reality. So when after that “oh, crap” moment, like, wow, I really, I really have to do this. What, what were some of those?

Hal Levison: Yes. Although, the team was already put together, right?

Host: I see. OK.

Hal Levison: You put the proposal together, right? NASA, you know, it’s, it’s an interesting process you go through…

Host: OK.

Hal Levison:…because NASA wants to ensure that any team can function under stress. What I like to say is the science wins a mission, but everything else can lose it. And so, everything about the mission, the teams, the instruments, the schedule, the cost, all was mapped out before we even applied, or at least the second level of applications. The way NASA does these big missions is they realize that no one can actually sit back and design a mission concept well enough with the limited amount of money that they have, right, to put in the proposals. So they do it in two steps. One is you put in what’s called the step one proposal, which for Lucy was about 125 pages, I think. OK. And it’s, I know my engineering colleagues would hate it when, if they heard me say this, but where you really do what I call LEGO engineering, you take this and stick it there and just take this and stick it there and that kind of thing.

Host: Yeah.

Hal Levison: Without really being able to do an analysis to prove to yourself it’s going to work. Then, so there were, I think, 27 proposals put in, in step one, NASA down selects the, in our case, five in which they gave us some money, and that allowed us to go and develop what we call the Concept Study Report, which is about a thousand-page document. And there are all the schedules, all the engineering, preliminary engineering, all the management style, you know, org charts and all that stuff was part of that proposal. And then we were selected in 2016, 2017.

Host: I see. Yeah. So it gives, it gives NASA, it gives others the confidence that, you know, there’s, they have a really good understanding of exactly what you guys are going to do. And then after that award is really, and you can keep correcting me along the way, after the award is really where the, you start to cut the hardware, you start to actually put the spacecraft together. You start to actually build the instruments, test the instruments. It’s, it’s, that’s post-proposal.

Hal Levison: Yeah. Yeah. I mean, there is a period where you’re refining the engineering…

Host: I see.

Hal Levison:…even after the Concept Study Report. But yeah, you have a preliminary design and NASA judges you on the preliminary design, and then you go into Phase C is where you really dot the i’s and cross the T’s, right? And so, sort of about a third of the way through that is when you actually start cutting metal, or at least that’s how Lucy worked.

Host: And so, if you were to sort of give a, you know, verbal description of the, of how Lucy looks and, and what, what are sort of its defining features when, you know, after refining and, and thinking about how, how to best build a spacecraft given its needs, given what it’s going to do, what are some of those key features that make Lucy Lucy?

Hal Levison: Well, I mean, Lucy sort of looks like Mickey Mouse because it has these two, large, almost circular solar arrays on either side. Lucy is going further from the sun than any other solar powered spacecraft in history. And as a result, we have these massive arrays. They’re roughly 7.3 meters in diameter, so they’re big, right? The spacecraft is roughly 50 feet wingtip to wingtip when the solar arrays are fully deployed. The bus itself is about 14-feet tall and on top of top, but yeah, you get the idea.

Host: Right?

Hal Levison: Of the spacecraft, we have what we call the instrument pointing platform, which is a gimballed platform that can point our instruments at our carts.

Host: OK.

Hal Levison: So you can think of it as a winged of a, a wing bat-type thing with a head. Think of that. That’s what Lucy looks like.

Host: Yeah. And, OK. Yeah. Described it perfectly. And really what Lucy is, and this, you know, this, this bat, this Mickey Mouse figure, what it really is doing is this is the spacecraft that’s holding the precious things that you and the science community cares about those instruments. And the instruments are giving you the data that you want that’s going to reveal the things that you, that you want to reveal about the Trojan asteroids. And so, what are some of those key instruments and what do they do? And, you know, how do, how does the data from them inform what, what you need to make your conclusions about the, the Trojans?

Hal Levison: So getting back to this idea that you want diversity, you need to visit a lot of objects. The way to do that, right, is to move really fast. After all, and we’re orbiting the sun three times, four times, right? But when we’re out at the Trojan distances, there’s basically two orbits around the sun. And so, we’re moving really fast. So we’re not, we can’t stop and sniff, we can’t touch the asteroids. All these things are remote sensing, basically camera-type instruments. But given that we’re doing about everything we possibly could to study these things as we go by. The first, which is not a camera actually is as we fly by, we’re going to be able to measure the gravitational tug of the Trojans on our car, on the spacecraft, using our high gain antenna. That’s going to allow us to measure its mass. Then we have two panchromatic cameras on the spacecraft. One, one is a wide-field camera that we call the terminal tracking cameras. It’s used mainly to make sure that the instruments are pointed at the targets as we fly by, right? We don’t really know where they are to within the size of the object. So Lucy, unlike some of the previous spacecrafts, like New Horizons that went to Pluto, it had to cover a large, what we call error ellipse. And a lot of the data that New Horizons took was with empty sky because they didn’t know where Pluto was, right? Lucy has a camera system and software that ensures that the cameras are always pointing at the targets, and that’s done by these terminal tracking cameras. They’re wide-field panchromatic cameras, but they’re also, designed in such a way that we’re going to be able to get the shape of our Trojans, right, by using these wide-field images. Then we have a basically a 10-inch telescope on, on Lucy that’s panchromatic. It’s high-resolution camera. This is going to allow us to observe basically the geology and count craters. We expect that we’re going to get down to something like 14-meter resolution with that camera. We won’t be able to cover the whole target with that. But one of the goals, scientific goals of Lucy is to measure the crater size distribution on the targets. So the crater size distribution tells us the size distribution of the stuff that’s hitting the, the targets. And that’s interesting from a, the point of view of planet formation, right, because right? If you think about it, planet formation is, has two processes in it. One is collisional processes, where things hit and either grow or break, and the other dynamical process, which allow these things to move around so that they can hit each other and grow or break. So one of the diagnostics to understand how planets form is in any small body population, what the size distribution of the optics are, because that is driven by the collisional process. Now, we know, look how many big Trojans there are, because we can see it from the telescope with our telescopes. But in order to really understand how collisions evolve that population, we have to understand what the small Trojans look like. We can’t see those from the ground or even from Lucy, but we can measure their sizes by looking at the craters on the bigger objects. So one of our primary goals is to understand and measure that size distribution. Another instrument we have on board, it’s actually two instruments. One we call L’Ralph. It, it has two parts. One is a color camera, and the other is a near infrared spectrograph intended to measure the composition. One of the interesting things, as I said, that some objects are gray, some objects are red, but we don’t know why? So the idea of doing this near infrared spectroscopy is going to tell us about the composition of the surfaces, and hopefully allow us to determine where in the solar system, or at least estimate, where in the solar system each individual object formed. Then we have a thermal infrared spectrograph on, on board. That’s going to allow us to measure things like the thermal inertia, how quickly the, the surfaces cool off or heat up when they move in and out of the sun. And what that’s going to tell us about is the physical characteristics, how fluffy the surface is of these objects. So that’s the instrument suite.

Host: Wonderful. And, and when you put all of them together, when you have all these pieces of data, the fluffiness, when you have, you know, the, the certain imagers, when, when you have all of these that tell you different, I, I guess stories about the asteroid, how do you, how do you compile all of these data and, and turn it into a concise… You know, here’s what we’re looking at. Why are the craters important? Why is the thermal spectroscopy important, or the thermal inertia important? You know, when you, when you add everything together, how do these data come and tell you a story?

Hal Levison: Well, the, the, the craters tell us the collisional history, right? Also, the shapes tell us the collisional history. There’s certain aspects of the shapes of our targets, which are really interesting. And we’ve been able to measure those from the ground. I think they’re telling us that they’re primordial objects, which are, or at least some of them are, which is really, very interesting, right? The chemistry will tell us something about where in the solar system these objects form, the temperatures at the time of formation, that kind of thing. The surface characteristics, again, will tell us something about the collisional evolution or maybe about the sizes of objects that these things form from, right? And how they came together to form the more, the larger objects that we see, right? And I can’t predict how we’re going to combine all that information because it depends on what they say.

Host: Yep.

Hal Levison: But all those things put together are going to be used to make, to constrain, right, these models of how the planets formed in the world.

Host: And all of these, Hal, I would, I would guess, are, are very precious in a, in a way. And so, the way that the system is designed, you have these capabilities on board to give you a certain level, I could even say, a, a significant level of confidence that when you’re passing an asteroid, that you are pointing those precious instruments in the right direction to get the data that you need. But you mentioned that it’s going fast. And so, when, when Lucy is traveling and passing one of these eight asteroids, what does that look like in terms of the way that the spacecraft moves and really, just how much time you have to gather these data?

Hal Levison: Yeah. Don’t blink is the answer to that question. So, so, you know, as I said earlier, this is a 12-year mission. The encounters are between about six and nine kilometers a second. So our objects, at least the smaller ones, are only going to be resolvable from the spacecraft for a couple of hours.

Host: OK.

Hal Levison: OK. The bigger one’s a little bit further. So, you know, we’re very careful about designing, you know, designing a sign sequence, it’s all automated, right? We can’t point and shoot, we can’t say, “oh, look at that” and, and tell the spacecraft to look here versus there. None of that is possible. Matter of fact, the spacecraft, because of the CONOPS, (concept of operations) is not even going to be talking to the Earth while the, these, these encounters happen, because they, the spacecraft itself actually flops over as we fly by. So, now, I, I want to put this in perspective, right? This is a 12-year mission, and almost all the important science is going to happen maybe in 20 or 24 hours.

Host: Oh, I see.

Hal Levison: Right? And the rest of the time is just getting between the targets. So another thing this spacecraft is not going to be able to do during the encounters is send back, send us back any data. So again, this is pretty typical for flybys. The, the spacecraft is going to be totally autonomous. We’re going to program it to do what we’ve told it to do, and then after it’s done, it’s going to rotate back, put its high gain antenna back on the Earth and then beam back the data afterwards.

Host: OK. So yeah…

Hal Levison: That enough. Is that enough information?

Host: It’s, it’s, it’s, it’s more than enough. Yes. That’s exactly what I was looking for, is you only have…

Hal Levison: OK.

Host:…you only have a couple of hours with, you know, at, at most with some of these, with some of these asteroids. But it sounds like, you know, the way that the mission is designed, you know, you, what you’re trying to do is capture as much of it as possible, can’t point the antenna because it’s the instruments are the most important part of pointing the right direction at the time of the encounter. You know, you can, and, and there’s so much time in between encounters, you can wait, you don’t need to have real time ops. They’re automatic anyway. So, you’re just sort of relying on the spacecraft and its design to, to give you what you need.

Hal Levison: That’s right.

Host: Yeah. And so, when it comes from an operations perspective, you know, it’s not — we, we, you know, this podcast mostly talks about human spaceflight and human spaceflight very much is 24/7 operations. When humans are in space, we’re looking at things all the time. And so, I wonder what Lucy operations look like, in terms of monitoring the spacecraft and making sure that it’s performing? Are you getting, you know, regular data or is it, is it incremental? Are there commands and, and are, and, and anything being issued to the spacecraft, or is anything, everything passive, everything’s coming from the spacecraft? What do those operations look like over a 12-year period?

Hal Levison: Well, I mean, they, you know, we’re monitoring spacecraft. We’re talking about it, talking to it all the time.

Host: I see.

Hal Levison: We have, they’re called, DSM (delta-sigma modulator) passages. We have a couple a week, if we’re not doing anything for monitoring, that kind of thing… operations, right? One thing about Lucy is, that, you know, our launch day was not perfect. It was beautiful, by the way, if your audience should look online on some of the Lucy launch videos, even people who live down there, told me that it’s one of the most beautiful launches ever.

Host: Wow.

Hal Levison: It was at, during, just during the beginning of Twilight launching at 5:34 in the morning. So, it was dark, and there was a cloud bank that the rocket went into and then erupted from the top of it. That was spectacular. Unfortunately, I didn’t see it. I was too close. So, I was under the cloud bank. So, for me, the rocket just disappeared into the clouds. But for those people who were a little further away, it was really a beautiful thing. So, people should look it up if they have a chance. But about an hour after launch, the spacecraft was separated from the launch vehicle, and we started deploying the solar arrays. And one of the solar arrays did not completely deploy. So as of now, these things actually unfold, sort of like oriental fans. And so, you know, complete deployment is 360 degrees, after a lot of work over the last year and a half, we are now, I think we’re about 355 degrees deployed. That changes the dynamical characteristics of the spacecraft. So, we’ve been quite busy actually trying to characterize that and redesign things like our control systems to make sure that the, we can, they’re stable as we do these activities. So, there’s a lot of work that’s been going on because of that. The spacecraft, we’re pretty sure is safe and we’re going to be able to do our work, but it’s been a lot of work. So, and normal just cruise, right? We have, you know, what we call the mission operations center, which is down at Lockheed Martin in South Denver. This is all Colorado mission, by the way, right? The launch vehicle, the science team, Lockheed Martin built the spacecraft. Almost all of it was done in Colorado.

Host: Cool.

Hal Levison: But, so they are, you know, monitoring the spacecraft, testing its systems. We’re doing a lot of calibrations. So, we take pictures of stars and that kind of thing on a fairly regular basis as we prepare for these encounters. The science team is extremely active now, right? I said it’s a 12-year mission, but the, the targets are not uniform, uniformly spread in time, because the Trojans sit in two clumps. One that leads Jupiter by 60 degrees and one that follows Jupiter by 60 degrees. It takes two orbits around the sun to get both swarms. So, starting in 2027, right, we’re going to enter what we call the leading swarm or the L4 swarm, and we’re going to have four encounters in 15 months. The first two are only 30 days apart. And so, all this needs to be planned before we get there. So, the science team, even as we speak, are planning what the spacecraft is going to do when it gets to these targets. So, everybody’s busy all the time.

Host: It must, yeah. It must be that way. And especially now, I’m thinking about the, the, the nearest term encounter. I’m thinking about Dinkinesh. The one that’s coming up later this year. And so, preparing for, for that encounter, your first encounter, what does that timeline look like in terms of, you guys are busy, you guys are checking out the spacecraft, you want to make sure everything is good? And then, you know what, what, what that operation looks like for the first pass coming up later this year?

Hal Levison: Yeah. Let me point out right, that we added Dinkinesh only a few weeks ago.

Host: Yeah. This is, yeah, this is a good point. That’s right.

Hal Levison: And so, you know, we had a schedule to prepare for our first encounter, which was, which is a encounter with a main belt asteroid called Donald Johanson, right? But that’s still a while away.

Host: 2025, right?

Hal Levison: Oh, by the, yeah, 2025. By the way, we named Donald that asteroid after the discoverer of the Lucy fossil, right? Most of our targets were not named before we decided they were targets. So we have gotten to name then. And indeed, Dinkinesh is the Ethiopian name for the Lucy fossil, which is how we came up with that.

Host: Very Cool.

Hal Levison: So, it was only, so, you know, way back when we were planning this, we had a schedule for what we would be doing right, until we got to Donald Johanson. This includes two Earth gravity assists, one that happened last October. And again, your audience should go off and look at some of the beautiful pictures of the Moon in particular that we took, right? That was to, you know, one of our goals is to get as small as craters as we can in smallest geometry, geology that we can on our targets. And we wanted to exercise the cameras to make sure we understood their behavior. So we had, that was a lot of work in and of itself, but we’ve added the fact that we need to understand how the spacecraft will fly, given the solar array isn’t latched. And as an extra test, because we wanted to see and understand the characteristics of the spacecraft now, right? We’ve added this target called Dinkinesh, which is a small, it’s about 700-meter, just main valve asteroid that’s in the inner part of the asteroid valve. So scientifically, it’s not very, very important. But as a test of our systems, it’s very important. By the way, it’s so small. We call it “Dinky.” Short for Dinkinesh.

Host: [Laughter] OK. That’s, that’s, that’s good to, that’s good to clarify, right? That this, this came up quick. That your timeline for actually making a pass moved up. But, you know, maybe you could, can get a little bit of science from it, but understanding the operations of what a pass is going to look like and having that sort of first go before you hit some of your more scientifically interesting targets is probably of, of great value to the Lucy team.

Hal Levison: Absolutely. That’s how we justified doing this.

Host: Very cool.

Hal Levison: I mean, it’s not a particularly interesting scientific.

Host: OK. So, so yeah, you’re going to be doing this pass here, coming up soon. And then, it’s, it’s a while in between each of these, each of these passes, like, like we’ve mentioned many times, it’s a 12-year mission. So, so there’s a lot. It’s a, it’s, it’s definitely a marathon when it comes to supporting this. And like you said, you know, there’s troubleshooting along the way. Teams are very busy. Do you have teams fully dedicated to Lucy, or are, do they wear several hats where, you know, they have to, they, they work on Lucy, but then, you know, they’re also working on other projects?

Hal Levison: Well, most of the people, I think, I must admit, I would have to look at that information, right?

Host: That’s fair.

Hal Levison: Most of the people that work on Lucy are part-time, right? But we have a core group of people, particularly, you know, probably something like ten or so down on Lockheed full-time. The management team here at Southwest [Research Institute] is full-time. Some of the key science people are, are roughly full-time, that kind of thing. But then, there are a lot of people like the science team who, you know, have multiple hats and going around doing different things and come together at critical times in order for us to design the sequences, for example.

Host: And what about you? Are you full-time Lucy? Are, are you, you’re going to stick through to the end and, and this is your, and this is your primary focus?

Hal Levison: It’s my only focus.

Host: There you go.

Hal Levison: It’s all I’m doing.

Host:[Laughter] So then…

Hal Levison: And it’s a full-time, and it’s a full-time job.

Host:[Laughter] And that’s, that’s, that’s important to note. It’s a full-time job to make sure that this flight is going to be successful over 12 years. But I think it’s also that it’s not just, you know, it’s, it’s 12 years of really data gathering. And I wonder what the analysis and the scientific aspect comes in with some of these passes. You know, are you doing it incrementally in between some of the passes, looking at some of the data, parsing it through, and then how, how far do you expect that to continue after the last pass in 2033?

Hal Levison: Oh, it takes a matter of weeks to get all the data down. So, you know, we’ll do a, we’ll, you know, we’ll do an encounter, and we will, we’ll send the data down after each one. The only exception to that may be the first two Trojan encounters. Everybody’s with a satellite Queta and, and Polymele, which is with its satellite, Shaun, they’re only 34 days apart. And so, we’ll get some of the key data down from the first encounter before we do the second. But most of the data from both will come down after the second account.

Host: I see. Yeah, because again, the primary focus there is the operations. You can’t be, yeah, you need to make sure that instruments are ready to go and checked out for that next pass.

Hal Levison: Exactly.

Host: Yeah.

Hal Levison: Exactly.

Host: So, so how, or what I wanted to do was sort of end with, and just kind of looking at Lucy as a whole and this sort of, and this sort of mission, this opportunity to go visit the Trojans. You, you, we started off the conversation about you talking about your time as a Theorist and coming up with ideas, and now, you’ve spent a significant amount of time and already indicated that you’re going to spend your, your primary and only focus is going to be seeing this mission through to the end. Just, I want to, I want to gauge your, your excitement and your passion for sticking with a project for this long, right? I mean, this is, this is obviously something that’s very meaningful to you and to the scientific community, and, and you want to see this through to the end. And I wonder what your thoughts are about just the mission, everything that led to this moment. You know, all of the different concepts, the planets aligning, the design, the launch, the issues that were encountered and, and we’re pushing through in order to make the science a reality. Taking all of that, all of that that we talked about today and, and putting it into perspective of what we’re trying to do and what we’re trying to learn here. What, what sort of drives you every day that you come into the office?

Hal Levison: Well, first of all, let me just say, you know, it’s, it’s awesome in the classical sense of the word.

Host: Yeah.

Hal Levison: Right? I mean, if you think about what we’re doing, I, I was just talking to my daughters. I have two daughters, they’re adults at this point. And, you know, and I was saying, yeah, Lucy just passed the over to Mars. I mean, think of that, right? You know, I mean, we really are reaching out to, you know, when I was a kid, right? The, I was a kid basically predated pioneer, right? Pioneer happened when I was in high school, right? Viking happened again when I was in high school. And so, you know, we’re, we’re turning, we’re turning these distant, astronomical objects, right? In the sense that you, they’re just lights in the sky to something that to real worlds. And trying to figure out where we came from, from that information, it’s, it’s truly awesome.

Host: In the classical sense of the word, Hal Levison, thank you.

Hal Levison: In the classical sense of the word.

Host: [Laughter] Hal Levison, thank you so much. It was such a extreme pleasure for me to get to talk to you today and sort of feed off of that passion, because what this is, is, is just super exciting and I hope our listeners are, are engaged and, and, and ready for that first pass and kind of learning, kind of tuning in along the way on, on all the milestones that you and your team are putting together. So, I appreciate you coming on to, to talk about Lucy today and, and, and we’re, we’re excited here on the podcast for sure. And we’ll be following along throughout the mission.

Hal Levison: I, I, it’s my pleasure, right? I really love Lucy and so, I’m happy to share with you.

Host: Awesome. Thanks, Hal. Take care.

Hal Levison: Bye-bye.

[Music]

Host: Hey, thanks for sticking around. It was awesome to get to feed off of the incredible energy of Hal Levison today. I hope you learned something and are as excited about Lucy as we are. You can check out NASA.gov for the latest, any updates that come out from Lucy. And then of course, if you want to listen to us and more podcasts, we have a number of them that you can find on NASA.gov/podcasts. There you can find us and listen to any of our episodes in no particular order. If you do want to talk to us, we are also on social media, and you can go to Facebook, Twitter, and Instagram on the NASA Johnson Space Center pages and use the hashtag #AskNASA on your favorite platform to submit an idea or maybe ask a question. Just make sure to mention it’s for us at Houston We Have a Podcast. This episode was recorded on April 21st, 2023. Thanks to Will Flato, Pat Ryan, Heidi Lavelle, Belinda Pulido, and Jaden Jennings. And of course, thanks again to Hal Levison for taking the time to come on our 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.