Lucy and Psyche Asteroid Missions Explore the Early Universe

JOHN DANKOSKY: This is Science Friday. I’m John Dankosky. Ira Flatow is away. Last week NASA announced two new missions set to launch within the next decade. The missions, Psyche and Lucy, are both headed for different asteroids.

Asteroids have the undeserved reputation as nothing more than space rocks that zip by the Earth, sometimes a bit too close for comfort. But asteroids are worlds of their own. They might contain water. Some are composed of rare metals. And they contain clues about the conditions of the early solar system and how the planets were formed and moved amongst one another. So pretty cool, right?

My next guests are here to fill us in on the upcoming missions and talk about asteroid science. Cathy Olkin is deputy principal investigator of NASA’s Lucy mission. She’s also a planetary scientist at the Southwest Research Institute in Boulder, Colorado. Cathy, welcome to the show.

CATHY OLKIN: Hi, John. Thanks for having me.

JOHN DANKOSKY: Lindy Elkins-Tanton is principal investigator of NASA’s Psyche mission and also director of the School of Earth and Space Exploration at Arizona State University in Tempe. Welcome to the show.

LINDY ELKINS-TANTON: Thanks so much. Thanks for having us.

JOHN DANKOSKY: And if you’ve got a question about asteroid science, want to know what else these missions can tell us about the early solar system, just give us a call. Our number is 844-724-8255. That’s 844-SCI-TALK. Or tweet us @SciFri.

So Cathy, I’ll start with you. Lucy is headed to a cluster of asteroids called Trojans. So what’s unique about a Trojan asteroid?

CATHY OLKIN: Yeah, Trojan asteroids are unique in a number of different ways. There’s actually two swarms of Trojans, and they orbit along with Jupiter in the same orbit. One swarm is 60 degrees ahead of it in its orbit, and the other swarm is 60 degrees behind. So they are in a very different location than most asteroids, and we believe that they are the remnants from a solar system formation.

JOHN DANKOSKY: Wow. And they’re all clustered around Jupiter because of its gravitational pull.

CATHY OLKIN: Yeah. These swarms that they’re in are stable points, and they got swept up as the solar system formed and they got trapped in these locations.

JOHN DANKOSKY: So this mission is going to go to six different asteroids. First of all, what do you want to learn at each of these stops, but also love to know how you’re going to weave in through all these asteroids.

CATHY OLKIN: Yeah, we found an amazing trajectory that takes us to both swarms, the one that’s ahead of Jupiter and the one that’s behind. So we’ll be able to sample Trojans in both locations. In the first swarm we fly past four of them, and we’re going to look at Trojan asteroids of different colors, different spectral types, which tells us something about the surface composition, and different sizes so that we can compare and contrast how these objects look at the geologic level and at the composition level, looking at the surface so that we can understand what happened to them and how they formed.

JOHN DANKOSKY: How close do you get?

CATHY OLKIN: So for most of them we fly by at 1,000 kilometers away from the surface. And for one of them we’re going to go closer. We’re going to go about 415 kilometers from the surface. And that’s because we want to be able to get the density of all of them, and the small one you have to get closer so that you can feel that gravitational pull.

JOHN DANKOSKY: Very cool. So Lindy, now your mission is headed to a single asteroid called Psyche. How did you identify this one as your target?

LINDY ELKINS-TANTON: Thank you. It’s so exciting. About six years ago we started wondering what would be the best place to go in the solar system to understand more about the very beginning of planet formation, this process called differentiation, when melting occurred and the heavy metal sank to the middle of planets, like our Earth core is metal.

And we found out that there is this wonderful asteroid, Psyche. It was the 16th asteroid discovered by people in the 19th century when we started discovering asteroids. And it seems to be just a world of metal with almost no rock on the surface of it. We think it had a lot of destructive collisions in the high speed high energy early solar system that just broke all the rock off the outside, leaving the core available for us to see.

And in fact, it’s the only core that humankind will ever be able to see, because we’ll never see our own. And amazingly Psyche is the only object like this, a small metal world, in our solar system. There are a few other metal asteroids, but they’re much smaller and funny shaped and they can’t be cores the way Psyche can.

JOHN DANKOSKY: So basically you imagine a small planet with all the other stuff broken off and it’s just the hard metal core and that’s Psyche is.

LINDY ELKINS-TANTON: Exactly. And since humans have never seen a metal world before, we really wonder what it’s going to look like. We have scientific hypotheses, of course, that’s kind of required of us, and we thought about it really hard what could be there. But like Lucy, one of the things that we want to do is engage everyone who’s interested in space or challenges or exploration. We want to engage you to think about what it might look like when we get there.

Some people say like the Death Star, that’s no moon, and to engage us in art and exploration and we’re on social media. And so let’s look for lots of ways to think about this strange metal world before we even arrive.

JOHN DANKOSKY: Are you expected to be surprised by what you see, like mountain ranges or gigantic craters? You don’t really know at all what you’re going to encounter until you get there.

LINDY ELKINS-TANTON: Well, the actual thoughtful scientific hypotheses we have the lead us to think that Psyche could have giant cliffs 10 or 15 kilometers high caused when the outer shell of Psyche shrank to accommodate the freezing and shrinking of the interior. And those cliffs could be made of iron-nickel metal or they could be made of the same material that calcite meteorites are made of, and that is metal mixed with bright green mineral crystals, which is a pretty mind-boggling idea.

It could have sulfur lava flows on the surface. The sulfur could be yellow or orange or white. And we wonder what craters would look like in a metal surface. They could be [INAUDIBLE] on the inside with breakages that look like feathers. They could have frozen metal spire. We don’t know. But the final message about this is every time we’ve explored the solar system, the solar system has surprised us. And so we expect to be surprised again.

JOHN DANKOSKY: Cathy, how about you? Do you have some guesses as to what these various asteroids are going to look like? Or are you going to be surprised too?

CATHY OLKIN: I think we’re going to be surprised too. Both of these missions are missions of exploration. We’ve never seen objects had this up close and seen what their surfaces look like. And what we’ve learned over and over exploring the solar system is that there are a lot of surprises out there. We learned that when we went to Pluto. So I’m not going to make any bets on what we’ll see. I just think we’ll be surprised.

JOHN DANKOSKY: I want to go to some phone calls. A lot of people have asteroid questions, like Steven in Naples, Florida. Hi there, Steven.

CALLER 1: Hello?

JOHN DANKOSKY: Hi, Steven. You’re on Science Friday.

CALLER 1: Hi. Long-time listener, first-time caller. And also to the guests, thanks for being on today. My question had to do with the asteroids you guys are talking about. It’s my understanding that they’re all in between Mars and Jupiter in the asteroid belt, but what you’re saying that some of these are coming you said around, orbiting around Jupiter? So I’m wondering how that happens.

CATHY OLKIN: Yeah, yeah. So when you learn about the solar system in school, you learn Mercury, Venus, Earth, Mars, and there’s an asteroid belt, Jupiter, and typically gets glossed over that there are other kinds of asteroids as well. And these Trojan asteroids. They don’t orbit around Jupiter, they orbit around the sun but it’s the same distance from the sun as Jupiter is. So they all are going around a big circle around the sun that’s five times more distant than the distance between the Earth and the sun. Does that makes sense?

JOHN DANKOSKY: And I think, Steven, that that’s the answer you’re looking for. It’s fascinating. I want to get to another caller who has a very different question, maybe a more practical question. Bruce in Charleston, South Carolina. Hi, Bruce, go ahead.

CALLER 2: Hi, how are you? My question was concerning the economic impact of these missions. I know there’s a lot of interest in potential asteroid mining. What types of materials are on these asteroids that could potentially be applicable here on Earth?

JOHN DANKOSKY: Well, that’s a great question. Lindy, can we get some minerals off of Psyche that might benefit us here?

LINDY ELKINS-TANTON: Well, of course. I’m just going to get to say the sad thing first, which is we have absolutely no way to bring this material back right now. Right now that’s technology that’s in our future. But I am here to say that day is coming. We have companies that are working on mining asteroids, looking at different things that can do with them.

And in the case of Psyche, it is made up mainly iron and nickel, but these iron and nickel cores have got copper and iridium and gold and platinum and rhenium and a lot of other trace metals that we are really interested in economically.

So a lot of times we talk about going to use resources on asteroids just in terms of squeezing water or heating water out of the rocks for jet fuel and for water. And that’s really important, but this metal is super interest. And I did the calculation based on the current middle-market prices last week. Psyche is worth about 100,000 times the global growth domestic product.

But just to underline this, we do not have any way to bring it back. But maybe in the future. It’s good to know it’s there.

JOHN DANKOSKY: It is good to know that it’s there. What else could it tell us about the core of the Earth, about our own planet?

LINDY ELKINS-TANTON: Yeah, this is so interesting to me. We don’t expect the cores of the super early planets like Psyche to necessarily have the same composition as the big, hot, high-pressure planets like the Earth and Venus and Mars. So what we’re looking at is the very beginning of how cores were formed. And there’s the idea, really interesting idea, that these early planets might have actually carried carbon and even oxygen in their cores to growing planets as they created and made them bigger and bigger.

So we’re going to be looking at what are the trace elements that are in Psyche that would have been delivered to the Earth by these little planetesimals as the Earth was growing? So that’s one of things we’re going to look at. And we’re also especially going to look at the magnetic field, because if Psyche was a core the way we think it was, it may very well have had a magnetic dynamo and have a strong frozen recorded magnetic field. And so when the surface we’ll actually be looking at a magnetic dynamo, something that we can never see otherwise.

JOHN DANKOSKY: So, Cathy, for you the big take away of visiting all these asteroids, these Trojan asteroids, is What Are we learning about the early solar system, about how things are moving around out there?

CATHY OLKIN: Yeah, so these Trojan asteroids, we believe, were captured when the solar system was being formed. One theory is that the giant planets migrated out and captured these protoplanetary objects as the solar system was forming.

And so these are the remnants of what would have gone into all our planets, and I’m so excited that NASA chose Lucy and Psyche, because I think there’s a lot of synergy between those two missions. And so I think we’re going to learn a lot about the early solar system formation from looking at these objects and how the core of our Earth might have formed by looking at Psyche.

JOHN DANKOSKY: I’m John Dankosky, and this is Science Friday from PRI, Public Radio International. I wanted to ask you both, and maybe Lindy I’ll start with you. The Rosetta mission to a comet collected a lot of interesting data, and it was really cool to watch, but it also had some technical problems. Are you learning lessons from that spacecraft and that mission?

LINDY ELKINS-TANTON: Oh, for sure. This is one of the amazing things about the process of space missions. We always learn, and there are lessons learned, meetings afterwards and all kinds of things. But for Psyche it’s actually going to be much more straightforward and based very much on the Dawn mission.

Psyche is much, much bigger than the comet that was visited by Rosetta. Psyche is about size of Massachusetts, it’s much more spherical in shape, so it doesn’t have– we don’t think– it might have locally really astonishing topography, but as a whole it’s more of a sphere. And so we’re just going to be orbiting too. We’re not sending a lander, so we’re going to orbit for 20 months and really look at this thing closely, from as close as about 100 kilometers.

JOHN DANKOSKY: Joey’s in Maryland. Hi, Joey. Go ahead.

CALLER 3: Hi. My question is what is to be done with the probes once they’ve finished their primary mission.

JOHN DANKOSKY: Good question. Cathy, what happens after you’re done taking pictures?

CATHY OLKIN: Yeah, so the Lucy mission is looping through the solar system and can continue encountering other objects after our prime mission. So right now we’re focusing on the prime mission and encountering these six Trojan asteroids, but we’ve looked ahead and saw that we can encounter other objects, including asteroids, in a potential extended mission that we would apply to NASA for permission to do, but that’s many years from now.

Our prime mission, we have our last encounter in 2033, so that’s looking pretty far into the future to talk about extended missions.

JOHN DANKOSKY: Lindy, how about you? After Psyche, what happens to Psyche?

CALLER 3: It’s almost certainly just going to wind down and end up on Psyche. And it’s not a landing. We’re very careful to say it’s not a landing. But probably just orbit closer and closer and crash.

JOHN DANKOSKY: A very quick question. I can’t get to a caller, though he’s wondering, can we guess how large the protoplanet was that this might be the core of?

LINDY ELKINS-TANTON: The smallest that it could be it’s something that’s bigger than Vesta, but the biggest it could be, something maybe even the size of Mars, because if it’s the whole core then it’s something that was just larger than Vesta, but if it’s a piece it’s, like a droplet of a core that was splashed out in a giant impact, it could be a part of a body even as large as Mars.

JOHN DANKOSKY: Mm. Cathy, before we go I have to ask you. Your mission is named after Lucy the early hominid fossil. What’s the connection?

CATHY OLKIN: Yeah, so it’s named after Lucy because the Lucy fossil transformed our understanding of hominid evolution just like the Lucy mission proposes to transform our understanding of solar system formation and evolution.

JOHN DANKOSKY: Lindy, what’s the thing you’re most excited about. Because I know this is still a couple of years away, but what’s the thing you’re most excited to look forward to here?

LINDY ELKINS-TANTON: I’m excited to actually see this new kind of world, this kind of world that humans have never seen. And I’m really hopeful and excited to feel the excitement of the world looking at it all together.

JOHN DANKOSKY: Cathy, how about you very quickly?

CATHY OLKIN: I am so excited to work with our partners and build a spacecraft and explore these new worlds. So the whole process is exciting to me.

JOHN DANKOSKY: You guys sound pretty pumped up about this. Cathy Olkin, deputy principal investigator of NASA’s Lucy mission is also a planetary scientist at the Southwest Research Institute in Boulder, Colorado. Thank you, Cathy. Thanks also to Lindy Elkins-Tanton, the principal investigator of NASA’s Psyche mission and also director of the School of Earth and Space Exploration at Arizona State University in Tempe. Thank you so much, Lindy.

LINDY ELKINS-TANTON: Thanks an awful lot. I appreciate it.

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