Planetary Radio • Mar 22, 2023

Getting psyched for Psyche

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Lindy Elkins-Tanton

Foundation and Regents Professor in the School of Earth and Space Exploration at ASU

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Bruce Betts

Chief Scientist / LightSail Program Manager for The Planetary Society

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Sarah Al-Ahmed

Planetary Radio Host and Producer for The Planetary Society

NASA’s Psyche mission to explore a metallic asteroid will launch later this year. Lindy Elkins-Tanton, the principal investigator for Psyche, joins Planetary Radio to share the mission’s status and look forward to the wonders that await when the spacecraft reaches its heavy metal target. We also keep you updated on exciting news from Venus, and let you know what to catch in the upcoming night sky in What’s Up.

Psyche the spacecraft at Psyche the asteroid
Psyche the spacecraft at Psyche the asteroid This artist's illustration depicts NASA’s Psyche spacecraft exploring the asteroid Psyche.Image: Credits: NASA / JPL-Caltech / ASU / SSL / Peter Rubin
Psyche the asteroid
Psyche the asteroid An artist’s concept.Image: NASA/JPL-Caltech/ASU
Mat Kaplan and Lindy Elkins-Tanton with Psyche
Mat Kaplan and Lindy Elkins-Tanton with Psyche Mat Kaplan and Lindy Elkins-Tanton in the JPL cleanroom with the Psyche spacecraft.

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Sarah Al-Ahmed: Space exploration is about to get a whole lot more metal. This week on Planetary Radio. I'm Sarah Al-Ahmed of The Planetary Society with more of the human adventure across our solar system and beyond. NASA's upcoming Psyche mission to explore a metallic asteroid will launch later this year. Lindy Elkins-Tanton, the principal investigator for Psyche, joins us to talk about the spacecraft and all of the strange wonders that await when we reach the mission's target. Then we'll turn to Bruce Betts and what's up for peak at the upcoming night sky and to look at this week in space history. Exciting news, scientists have found possible evidence of active volcanism on Venus. The discovery was made using data from NASA's Magellan spacecraft, which orbited Venus from 1990 to 1994. Two grainy radar images taken eight months apart show a volcanic vent morphing from a circular depression into a larger kidney shape, indicating possible volcanic activity. There are alternative explanations, but this finding provides an important data point for scientists trying to understand why Venus transformed from a potentially habitable planet to a total hellscape. Our new article on the subject written by our senior editor, Jason Davis, is available at A newly discovered asteroid has a small chance of hitting earth in 2046, but don't panic, the asteroid named 2023 DW was discovered on February 2nd. It's the only asteroid that currently ranks higher than a zero on NASA's Torino impact hazard scale. That's the scale that categorizes the projected risk of any object colliding with our planet. 2023 DWs ranking of a one on this scale means that its chance of colliding with our planet is extremely unlikely and there's no cause for public attention or concern. As more observations help us better define the asteroids orbit, it's pretty likely that we'll find out that its probability of hitting our planet is zero. But it does underscore the continued importance of finding, characterizing and tracking near earth objects that could pose a threat to our planet and all of the creatures that live here. Ain't nobody got time for a repeat of what happened to the dinosaurs. Am I right? This next story will tug at your heartstrings, but that's okay. NASA is making plans for how to de-orbit our beloved International Space Station. As much as we all wish the ISS could remain in orbit forever, the time has come to prepare to bring it safely down to earth. The agency's latest budget request includes funding to develop a module that will tug the station to a lower orbit. That way we can ensure that the ISS reenters Earth's atmosphere over the South Pacific. That's a place where large spacecraft can most safely crash down to earth. The ISS has been continuously occupied since 2000 and is scheduled to come down in 2031. In happier news, get ready to find out which astronauts will get to fly around the moon. NASA and the Canadian Space Agency are due to announce the crew of the Artemis 2 mission on April 3rd. Mark your calendars. The crew will include three NASA astronauts and one Canadian astronaut. They'll conduct a 10-day mission beyond the moon testing the Orion spacecraft systems before it takes another crew to the lunar surface with the Artemis 3 mission. You can learn more about these and other stories in the March 17th edition of our weekly newsletter, The DownLink. Read it or subscribe to have it sent to your inbox for free every Friday at Now it's on to our main subject for today, NASA's Psyche mission. I am so excited about this. There have been several missions to explore asteroids over the years. DON, Hayabusa2, OSIRIS-REx, and let's not forget DART. They were all amazing. But NASA's upcoming Psyche mission, this is a whole new ballgame. The Psyche spacecraft aims to study the asteroid of the same name, Psyche, which is located in the asteroid belt between Mars and Jupiter. It's an intriguing object, and by that I mean it's really, really weird. Asteroid Psyche is believed to be made almost entirely of metal. We aren't sure yet, but this rare metallic asteroid may be the exposed core of a protoplanet that was destroyed in the early stages of formation in our solar system. We have to check this thing out. It could teach us so much about our solar system's formation. Not to mention that the images of the strange metallic world are going to be absolutely mind-blowing. NASA's Psyche mission aims to launch on a SpaceX Falcon Heavy rocket later this year. Dr. Lindy Elkins-Tanton is the principal investigator for NASA's Psyche mission and the Vice President of Arizona State University's Interplanetary initiative. She's also a foundation and region's professor in the School of Earth and Space Exploration. Her most recent book, A Portrait of a Scientist as a Young Woman, is one I highly recommend. She joins us to preview what the Psyche mission has in store. Hi, Lindy. It's great to have you back on Planetary Radio.

Lindy Elkins-Tanton: Hey Sarah, thanks so much for inviting me.

Sarah Al-Ahmed: I want to say I was very moved by your last appearance on the show. I loved your book, A Portrait of a Scientist as a Young Woman, so if we ever bump into each other in person, I hope you don't mind, I'm going to ask you to get it signed.

Lindy Elkins-Tanton: I would be super honored and thank you for that.

Sarah Al-Ahmed: I'm really interested in the Psyche mission, because honestly, the mission itself and the object it's going to go explore are so interesting. This asteroid is so weird, so I'm glad we get a chance to chew through it together. For people who are unfamiliar with the Psyche mission, what is it? What will it be exploring?

Lindy Elkins-Tanton: The Psyche mission is named after the asteroid Psyche, which orbits out in the main belt between Mars and Jupiter. Now, why would we want to go to this asteroid among the, what's the estimate between one and 2 million asteroids in the main belt, I think? So here's this one particular one. It's because it seems to have a metal surface and we as humans, we visited bodies made of rock, like the Earth, and bodies made of gas and ice like Jupiter and Neptune and icy moons. But we have never visited a metallic body and there are only a few in our solar system. We think maybe nine of the asteroids are made of metal and this is the biggest one. So I kind of feel like it's the space equivalent of discovering Antarctica. It's a new kind of place that humans have never been, and frankly, it is a big mystery, which is what makes it exciting to me.

Sarah Al-Ahmed: Yeah, I think at this point, and this is weird to say, we're almost accustomed to these asteroid exploration missions where we stumble upon a rubble pile or something, but this one is so weird and I don't think people have any real recognition of how cool it's going to be when we get images back from this thing. It's going to be wild.

Lindy Elkins-Tanton: I hope so. I hope so.

Sarah Al-Ahmed: And for people who have been following along with your previous Planetary Radio adventures, when last we left our heroes, which is you and the Psyche mission team, you were hoping that this was going to launch in 2022, but unfortunately the mission was delayed and I'm sure everyone is aware that it's been a challenging few years.

Lindy Elkins-Tanton: Hasn't it? Yeah.

Sarah Al-Ahmed: So how much did the COVID era kind of play into this mission delay and what kind of happened there?

Lindy Elkins-Tanton: Oh my gosh, so heartbreaking. We were selected to launch in August last year. And keep in mind, we've been working on this since 2011. It's not like we just started the minute before. But there's a really important moment in a development called the Critical Design Review, CDR, and our critical design review was May of 2020. And so it was just after COVID hit, it was the very first virtual review that NASA ever did. And the significance of the CDR is that when you pass it, you're really given permission to build the spacecraft. So fundamentally, our team has been in crisis mode since 2020, not just about our personal lives and our families and friends and the world around us and the economy and how people are living through the pandemic, but because we are trying to build a giant spacecraft through COVID. JPL was closed for months, no work happened and we had equivalent kinds of disasters at our subcontractors. So that absolutely contributed. The team was heroic and we almost made it. We almost made it. We delivered a fully functional spacecraft to Kennedy. And what we didn't quite finish was the testing and final writing of our guidance navigation and control software. But that was just the proximate cause, because honestly, we had really been rushing to try to make it, because it really matters. And so getting this extra year that we got has helped us tremendously and we're going to launch with a lot more assurance in October. Things are going well. So there was a lot of COVID in it. There were staffing issues partly caused by COVID. I mean, it weaves through everything, doesn't it? And so really my takeaway was heroic team, lessons learned for next time, and boy, last year was a very painful year for everybody and I think that we're back up on our feet.

Sarah Al-Ahmed: Yeah. Unfortunately, the delay to the Psyche mission kind of had some knock on effects and necessarily meant that NASA's upcoming mission to Venus Veritas has been delayed as well. So I think it's really important that everyone kind of remembers that space is hard and it's important that we do these things right and sometimes unforeseen things happen.

Lindy Elkins-Tanton: It is so painful to see Veritas delayed and we are all fighting not to have it canceled, which it's not on the table, but you worry, right? You worry. We really believe in that mission, all of us and many things, staffing issues, budgetary issues, NEA Scout and Psyche mission all contributed to just an inability NASA thought to move forward with Veritas right now. But boy, we really, really want it to go.

Sarah Al-Ahmed: Yeah. And I know a lot of Planetary Society members really want that mission to go.

Lindy Elkins-Tanton: Oh my gosh.

Sarah Al-Ahmed: So if that ever did happen, I know that we could rally everyone around the world.

Lindy Elkins-Tanton: Everyone, everyone.

Sarah Al-Ahmed: So hopefully support that mission.

Lindy Elkins-Tanton: Yeah, I know we're strategizing about that all the time. We have a group of PIs that get together about what can we do, and talking to headquarters and especially with this brand new information about recent volcanism on Venus, that makes it even more exciting. And so that's an extremely important mission and whatever our contribution was to their troubles is a great sadness to me.

Sarah Al-Ahmed: We actually just came out with an article about that, the Venus volcanoes yesterday, and I'm really hoping to get someone onto the show to talk about that as well, because that discovery is just so fascinating.

Lindy Elkins-Tanton: It is so timely too. It's perfect, actually.

Sarah Al-Ahmed: Perfect. It's perfect. Yes. But all of that said, this has only really created a one-year delay for the Psyche mission. So what is our new target launch date?

Lindy Elkins-Tanton: The new target launch date is 10:00 AM local time on October 5th, at Kennedy in Florida. So our launch period is October 5th to 25th. God willing, we will launch straightaway on October 5th on the beautiful Falcon Heavy with its two side boosters that are going to be relanded with the loudest sonic boom you've ever heard in your life, and it's very exciting. So that's what we're hoping for.

Sarah Al-Ahmed: Do you get to be there for the launch?

Lindy Elkins-Tanton: Yeah. I'll be in mission control, which is a privilege that I try not to just anticipate too much, because it's so exciting, but it's getting a little ahead, we've got seven months to go. But we did get to go, a small part of our team, the critical people who really need to be on console, and then I got to tag along as PI, we got to do that for the launch that happened last November of the Falcon Heavy where they were relanding the boosters, and I mean, it was mind-blowing. We got to play with all the GUI, the graphical user interface, opening up all the windows and trying to figure out what we wanted to be watching in terms of data during the launch. And you're in the darkened room and the big screens up front, all the cameras and the refueling is completed just minutes before launch. It's super dramatic. Then the minute the rocket went up, there was this sucking sound and everyone in the building ran outside to the parking lot so we could watch it with our eyes. I mean, obviously the critical people were still there, but there were a lot of us in the parking lot. And then it was early morning in Florida and there was a big fog bank and we saw the boosters start to come back down and then they went into the fog bank, but they land only three quarters of a mile away from mission control. There was a little gap between the land and the bottom of the fog, and they just appeared and then they immediately turned on their engines with this gigantic boom that shook the whole building and they landed and one of the car alarms went off in the parking lot and it was the Tesla, the Tesla alarm went off. So we kind of loved that. The whole thing was so perfect. So that was practice and then I'll be able to really pay closer attention when it's us in October. I'll be less overwhelmed by excitement.

Sarah Al-Ahmed: That's so exciting. Being in mission control at Kennedy Space Center has got to be one of the ultimate space life goal dreams right there.

Lindy Elkins-Tanton: I just feel so, so lucky for that and I think we're going to make it, the team is just amazing. We're really doing well.

Sarah Al-Ahmed: I know during the last launch window you had quite a bit of time with which to launch this mission. It was almost like three months or something if I read it correctly. Do we still have that much wiggle room with this launch given its timing, or is there some reason why you're kind of limited?

Lindy Elkins-Tanton: That's right. It's a more traditional NASA launch period this time as just fifth to the 25th. An interesting thing to me is that, so that's the launch period, those 20 days and a launch window would be how much time each day that you could launch. And none of these have windows. They're all instantaneous launches at a specific time every day. It seems like, to some extent, the era of the launch window where it could launch between say 10:00 AM and noon on a given day is over, because of the amount of orbital material we have around the earth. We have to track it all and make sure the rocket's not going to hit it. And so that launch time is an instantaneous launch, and if we don't make it that day, it's the next day. So that's interesting to me, that's a bit of a change in launches.

Sarah Al-Ahmed: That is, because people do have concerns about what happens if our satellites crash into each other. We end up with a bunch of debris and shrapnel, but we're not even at that point if already we have so many satellites that it's impacting our timing for launches.

Lindy Elkins-Tanton: Isn't it amazing?

Sarah Al-Ahmed: That is really interesting.

Lindy Elkins-Tanton: Yeah. We need more solutions for debris. Lots of people are working on it, but we need more.

Sarah Al-Ahmed: Absolutely. But assuming that this launch goes off on time, that's going to actually put this mission at the Psyche asteroid sometime between 2029 and 2030, is that correct?

Lindy Elkins-Tanton: Yeah, it's going to be summer 2029. That's when we're going to arrive probably August is what we're looking at, but there's a little bit of wiggle room there, so it's a longer time to get there. Unfortunately, last year was a better and more advantageous launch, but it's all fine. The spacecraft is fine for the extra trajectory time and lots of exciting things will be happening during those years, I'm sure.

Sarah Al-Ahmed: Yeah. What are you most looking forward to during that kind of calmer time when you're waiting for it to get there? What are you going to be doing?

Lindy Elkins-Tanton: Well, lots of things. We'll be planning in much more detailed science, prox ops when we're in orbit, because recall, this is an orbiter and not a lander or sample return. We're going to orbit for 26 months, and so there's lots and lots of planning to be done. Then expectations of publication plans and team organization, all of that we'll be doing, and then weekly check-ins and daily check-ins with what's happening at mission control for the spacecraft. But I think one of the most exciting things that's going to happen during those years of trajectory is the practice with the Deep Space Optical Com, our tech demo that we're flying, and this tech demo is to test or practice transmitting information between earth and the spacecraft using lasers instead of radio waves. As it turns out, you can encode a lot more information in a laser than you can in a radio wave. And so that's going to be really, really exciting to see that happening.

Sarah Al-Ahmed: I think that's really cool for a couple reasons. As we get to the point where, as we saw with the Perseverance Rover landing on Mars, we're trying to send back bunches of video during landing, audio, all of these things that are really hard to transmit back to earth. So an opportunity like this to play around with a laser system to send information is awesome. And I'm wondering, is it just mostly about being a tech demo or is there something about the information we're going to be getting from this mission that necessitates that bulk of data coming back to Earth?

Lindy Elkins-Tanton: No, it's completely separable from the science mission that's required for the tech demos, and in fact, we're not going to be using it when we're at Psyche at all. The advantage of laser over radio at Psyche's distance is minimal. The Deep Space Optical Com is an astonishing piece of technology. And one of the things about it is that it requires pointing precision, pointing back at earth more precise than the Psyche spacecraft needs. So in order to work, it actually detaches from the spacecraft. Now it's in a cage, so it can't float away, but it's literally not attached to the spacecraft and then it uses electromagnets to point even more precisely toward the earth. So that's really amazing. But turning on electromagnets will pretty much mess up our measurement of the magnetic signature of the asteroid. And so for a number of reasons, we are not even going to turn it on when we're out there. It's totally separable.

Sarah Al-Ahmed: That makes sense. Still really cool though. I can't even imagine a future where we've got a really robust deep space network that's just laser pew-pewing information all across the solar system.

Lindy Elkins-Tanton: Isn't that great? And we're joking that it's like that's how we're going to get Netflix on Mars.

Sarah Al-Ahmed: I think that would be the most challenging thing about trying to get people to actually live on Mars. What do you do without the internet? What do you do without your Netflix?

Lindy Elkins-Tanton: No streaming service. No cat videos. Oh, my gosh.

Sarah Al-Ahmed: No, that's my personal nightmare. I'd still say, "Yes, but." And I'm really excited about the launch of the spacecraft, because asteroid Psyche, as I said, is so weird. We're so used to asteroids that are just a giant rock or even a pile of rocks, but-

Lindy Elkins-Tanton: That's right.

Sarah Al-Ahmed: ... this thing is something else entirely, a metal asteroid. My gosh, what are we even going to find there?

Lindy Elkins-Tanton: Right. So Psyche asteroid kind of vies with an asteroid called Cleopatra to be the densest known asteroid. Cleopatra is another one of the ones we think is made of metal, and it's shaped like a dumbbell. It's a crazy fragment. It's the same shape that you get if you have liquid that is translating and rotating as it freezes. It can freeze as a dumbbell. So in my mind, that's what Cleopatra is. It's a bit of shrapnel that froze, but the density of psyche means that it's partly metal and partly something else that's lower density. It's so much denser than your average asteroid. It's probably about 4,000 kilograms per cubic meter. And almost all other asteroids are less than a 1,000 kilograms per cubic meter, because they have so much void space. They're rubble piles like you say. So their mass becomes an average between what they're made of and nothing. The void space. So the question is, how do you make an object that's made of metal and something else, and what is that something else? Is it rock? If it's rock, it has almost no iron oxide in it according to its reflected light spectra, which if you're a geologist, that's pretty weird. There aren't that many rocks that don't have any iron oxide in them. And so could it be even something else? Could it be sulfur? Could it be carbon? Or is it just really low iron rock? Don't know? And how is that rock and metal distributed? Is it giant chunks? Is half of the asteroid metal and half of it is rock? Is it mixed on the centimeter scale? How do you make that and what is it going to look like? In the lab when people do hyper velocity impacts into metal? And think for a second, we've never seen impact craters in a metal surface before, just in rock and ice. That's all we've seen. What is an impact crater in a metal look like? Well, little ones in the lab, the impactor comes down and it causes them with a shock wave and it creates the crater. And there's these splash, these ejecta, these rims that normally just fly up and then fall down outside of the crater. But if a small impact in a metal, those ejecta flaps freeze before they fall down. And so they're like spiky standing up walls and spikes. And so all the tiny micro meteorite and small meteorite impacts into Psyche's metal surface could be creating these kind of crown shaped spiky little pockets all over the surface. So we really don't know. So those are a few of the crazy things we're thinking. And the only thing I can say to you for sure right now is probably everything I tell you is wrong and that when we get there, it's going to prove to be something entirely different, because we're just making our best guesses with our curious minds that we can.

Sarah Al-Ahmed: And isn't that magical to have a situation where you're right on the cusp of having everything you think you know about something completely changed, but we've got some great information here. But I mean, when I hear about an object like this where it's got to be mostly metal, but it's got to have some other kind of material in it, I always imagine you've got a core of metal and then you've got a layer of something on top. But our spectral data on this does not suggest that. It at least partially has to have a metallic surface and that is so weird. And of course, it kind of speaks to the strange formation of this object-

Lindy Elkins-Tanton: Right. That's right.

Sarah Al-Ahmed: ... because people think that it's probably the core of a planet that never got fully formed.

Lindy Elkins-Tanton: Yes, that's our simplest idea, that we know that very, very early in the solar system all within more or less the first 3 million years out of the 4,568 million years that there have been in our solar system. So if it was a 24-hour day, within the first 10 seconds, these bodies called planetesimals forms the size of cities or continents, and that some of them heated up enough from radioactive aluminum 26 that the metal in them melted and flowed to the center to make a core. So in our simple, almost reptilian human brains trying to figure this out, that's where we go to when we think about a big clump of metal that comes from the asteroid belt. It must be part of the core of a planetesimal, but there's lots about planetary formation we do not understand. We've never seen it, right? We just infer it from the fossil remnants in our own solar system. Then observations of very distant new solar systems what we can't see in detail. So one thing I'm sure about is that we do not know the whole story. And so it's hard to know where Psyche would fit. And the other thing that comes into my mind about this is the use of Occam's Razor. That the simplest explanation would be the correct explanation. And this idea that Psyche's part of the core of a planetesimal, that's kind of an Occam's Razor answer, even though stripping the rock off the outside takes quite a number of impacts that remove material and don't add it. So in itself, that's a very unusual event. But of course, there's only one Psyche, so maybe that fits. So my question is, can you use Occam's Razor to explain a singular object or can you only use it when you're looking at a population of objects that have some kind of normal distribution? So you can say, "Well, yeah. Then obviously something common happened that created so many of them, or really, we are looking at a bizarre object and it requires a bizarre explanation." So from my point of view, the more bizarre the better. So I don't know, we're going to find out when we get there.

Sarah Al-Ahmed: We'll be right back with the rest of my interview with Lindy Elkins-Tanton after the short break.

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Sarah Al-Ahmed: As you said there, there's so few objects in our solar system that are anything like this, so we can try to make a guess. We can see the patterns in other asteroids and try to apply Occam's Razor here, but chances are there might be something really weird going on with this object. And I'm wondering, as you said, you'd have to pummel this thing a lot to blast off the outer layer of rock if it was the core of a planet. But at that time, maybe it was warmer, maybe a lot of the evidence of that pummeling has disappeared as the object cooled. I have no idea. Is it possible that we could find some evidence of this bombardment on the surface?

Lindy Elkins-Tanton: Well, the bombardment that stripped the material, if in fact that's what happened, we probably won't see too much of that because it would be hot and overlaid by ongoing bombardment over time. But we would expect then that the rock on the surface would be parts of the parent body, in which case it would be mantle rock, which would be in meteorite terms, a [inaudible 00:26:36]. And so if we see that, then that's a good indication that this planetesimal hypothesis is correct. The person who's worked on this really a lot is Eric Asfog at University of Arizona. And he and his team have done many, many, many models trying to create Psyche. So you can either hit a planetesimal with smaller collisions, say eight to 11 times without any collisions that actually add material in order to make what we see. Or you can have a kind of hit-and-run collision between much bigger objects and then the striking object actually has a lot of its exterior ripped off it as it passes through the impact E, so to speak. And so that's an interesting idea, because you can do it really with just one impact that way, but it's between much bigger objects. Think about something like the moon or even Mars. Could that be Psyche's providence? Could it come from a much bigger object? I'm not sure we're going to really be able to tell the difference between those scenarios.

Sarah Al-Ahmed: Conceivably, maybe that extra material on there that isn't metal is part of that other object that hit it. How would we even be able to tell the difference? This object just poses so many strange questions and I'm sure it'll get even worse when we get there.

Lindy Elkins-Tanton: I think it might. To make sure the team cultures at a really high peak of a cooperation, because all these answers that we're looking for are going to require data from all of the instruments and investigations. And one of our challenges is keeping our mind really open. We've done our best to design a spacecraft and go to an unknown object and we hope get all the data we need to discriminate among many scenarios. It's hard to know till what the object is.

Sarah Al-Ahmed: Yeah. But if it is in fact what could have become the core of a planet, this is a really rare opportunity, because even on a planet like Earth, trying to dig even a few kilometers below the surface is impossible at our current technology. The idea of even getting anywhere near the core on earth, let alone another planet, is so far beyond our capability. So I'm sure this presents an opportunity for learning things about solar system formation and planetary cores that we've never had before.

Lindy Elkins-Tanton: Yeah. No matter what Psyche ends up being once we're there, maybe it is a part of a planetesimal core, maybe it's some other kind of super reduced material, we're going to be looking at ingredients for planets that we've never seen before. If you think of the earth as sort of the layer cake and we're trying to understand what the eggs and the flour and the butter were, this is a new ingredient. And if it is the core of a planetesimal, though you are right, this is the only way humans are ever going to see a core, even in the distant future when we have the technology to go to the core, it's hard to know why we would ever spend the energy and materials to do that. Nasty, nasty temperatures and pressures down there so far beyond our capabilities. So as my husband says, "We are going to outer space to examine inner space."

Sarah Al-Ahmed: Yeah, there's so much amazing science that's going to come out of this, but one of the things I'm personally looking most forward to are the images, because as you said, the surface is going to be really strange. I really want to know what those craters are going to be like, because the artist's concepts of this object, giant ball of metal, huge spiky things coming out of the ground, I want to know what the difference between the large craters are and if those edges are actually sharp like razors. It's going to be nuts.

Lindy Elkins-Tanton: It's going to be nuts. And we've been so fortunate to work with Peter Rubin, this very talented Hollywood designer, to help us imagine what the surface might look like, because it's hard to get people super excited about something where you're only picture of it makes it look like yet another star. So I spent weekends on Zoom with him for, I don't know, a year, two years downloading into his great brain, all of the science ideas we have about this body, and he turned them into art. Indeed, they're just concepts right, probably wrong, but they're our best guesses. So yeah, small creators might have these razor sharp points or edges and the big creators probably will not, but we don't know. We don't know. And what we have done, and this is Jim Bell and the imager team, they have already built the pipeline so that our pictures of Psyche are going to be on the internet within a half hour of our receipt. We are not going to edit them, we are not going to do anything to them. We're going to share them with the whole world for free on the internet immediately so we can all be scratching our head, as he says, going, "What is this thing?" All at once, the same time.

Sarah Al-Ahmed: Yeah. And then all of the image processors get to jump in there and make them beautiful and post them all up on the internet for all of us. I'm loving this model of just dumping the images online for everyone, because I remember those days when I was a tiny kid on the internet just waiting for that one moment that an image from NASA popped up on their website. It's a whole new age and I'm really grateful for all that art of this, because years ago when this mission was announced, I was working on a totally different science show and we had a wonderful time taking those images and making all these heavy metal jokes out of it. It was perfect.

Lindy Elkins-Tanton: We talk about that a lot. In fact, it was Jim Bell who started that years and years ago. He was just very excited at the end of one of our small team meetings way back before we submitted our step one proposal back when there was literally zero chance we were going to be selected for flight, because as you and many people listening know, it's a really serious three year, two-step competition to get to fly. So Jim comes into this meeting, he's like, "Psyche, it's so heavy metal, we've got to get Mohawks, we've got to get piercings." But then we kind of settled down and we agreed that if we were selected for flight, we get tattoos and six of us have.

Sarah Al-Ahmed: Really? What are the tattoos of?

Lindy Elkins-Tanton: Anything you want. So mine is my own hand drawing of a planetesimal showing the metal core in the middle and then the convecting rocky magma ocean on the outside and a crust. And I put it on my hand, because this is about having agency in the world and doing things with your hands. And I'm in my 50s and I haven't colored my hair in a while and it's kind of silvery and I do not look like a chick anymore. And so my lovely tattoo artist, this young man is looking at me very earnestly and saying, "I really advise you don't get it on your hand, because people are judgmental and you'll have trouble getting jobs."

Sarah Al-Ahmed: I think that's part of what's so special about being a scientist these days. I honestly, right out of university, wanted to get my favorite equation tattooed on my arm right here.

Lindy Elkins-Tanton: What is your favorite equation?

Sarah Al-Ahmed: The Friedmann equation. It's part of cosmology and kind of the shape of the universe, all of the different things that go into that. I spent forever deriving all these different forms of this equation and I wanted to get it on my arm. And then one of my friends was like, "What if you end up being a teacher, you're going to have to wear long sleeves for the rest of your life." And I was, "Oh, no."

Lindy Elkins-Tanton: Oh my gosh.

Sarah Al-Ahmed: Because I might. I might have been a teacher, so I decided not to get the tattoo, but as soon as I got this job as host of Planetary Radio, it came right back up again. I was like, "I should get that tattoo."

Lindy Elkins-Tanton: You should totally do it. I was kind of hoping your favorite equation was Navier-Stokes, because that's my favorite equation. Fluid flow.

Sarah Al-Ahmed: I love that. Something else I'm really hoping that we can find some photographic evidence of, is potentially old volcanoes on this object. I know there's some thoughts that maybe when it was younger, more molten, maybe there were literally volcanoes spewing liquid iron on this thing.

Lindy Elkins-Tanton: Yeah, we've had this idea from the very beginning of the proposal and it actually shows in the art that we worked on with Peter Rubin and since then some people have written some papers about it, about how it's plausible. Here's the story, the iron and nickel that makes up the cores of all of our rocky planets and the iron nickel meteorites that fall from space. They all have other elements in them as well when they're in the core stage, sulfur and phosphorus and things like that. The minute they start to crystallize, they crystallize out crystals that are just iron and nickel and those crystals exclude all those other elements. They just are not compatible with the crystal structure. Right away the rest of the liquid separates into two admissible liquids just like oil and water. One of them is mainly iron and nickel and the other one is sulfur and iron, more or less in equal ratio of sulfur to iron. It's the liquid form of the mineral Troy light. And so this has been shown in the lab and it's been shown geochemically and it's pretty inescapable. And the thing about that sulfur rich admissible liquid is that it's much less dense than the other one. And so we thought, "Well, if it's freezing from the outside, as the crust freezes and there's evidence from some meteorites that they froze from the outside in, their parent body froze from the outside in, so it's not just fantasy, then that outer lid is actually going to be needing to shrink as the material inside it continues to crystallize and become more dense." There'll actually be a reduction in space as the liquid on the inside freezes into a denser form. So the crust is going to have to break up into faults and reshuffle itself and accommodate the smaller interior as it freezes. That we thought would squirt the sulfur liquid out through those faults onto the surface. And so that was our idea and people have other ideas. One idea is that maybe even the iron nickel liquid itself could be squirted out. I really, really, really hope we see some evidence of what happened to the sulfur, because this is a little mystery in meteorites that the iron nickel meteorites all show evidence of having crystallized in the presence of sulfur, but there is not enough sulfur now with them to explain that. So where is the sulfur?

Sarah Al-Ahmed: Another really cool thing about the spacecraft, as you said, it's testing different technologies that we haven't tried before, and one of those technologies is the new solar electric propulsion system, right? How does that work?

Lindy Elkins-Tanton: Oh my gosh, I love this. It's the most efficient way to move through space and it's the way that you can go to the outer main asteroid belt on a discovery class budget. And so what we did was we partnered with Maxar up in the Bay Area and they build these all the time. So for them, this is literally production line stuff, giant unfolding solar arrays. Ours will be 20 kilowatts here at Earth. And that electrical power, first of all, it powers everything on the spacecraft and then it also powers the propulsion system. What the propulsion system is, it's a giant tank of xenon over a 1,000 kilograms of the noble gas xenon, which normally is not reactive. That's what noble gases are, that's why they're called noble gases. They don't interact with anything. But if you use your solar electricity to ionize them so they have a charge, then you can send them through a potential field, an electrical field or a magnetic field that will shoot them out, because of their charge, kind of like a little accelerator, like those superfast rollercoaster, electrical accelerators, a little bit like that. It turns out that just the momentum exchange of those tiny atoms going out the back of the thruster pushes the spacecraft forward. So it's slow, but very, very, very efficient. And so we are flying four of these Hall effect thrusters, and this is the first time that Hall effect thrusters have been used outside of earth moon orbit, but they're the standard issue thing that Maxar flies in over a 100 telecommunication satellites that are orbiting the earth. So we do have a lot of faith in it.

Sarah Al-Ahmed: Yeah, it's wonderful to see new propulsion systems in place, because I remember what happened with the Dawn mission and their ion thrusters and everything they got to accomplish moving from object to object. The more options we have for sending our spacecraft in new ways, it's mind-blowing what we could achieve with things like this. So I'm excited to see this thing get tested.

Lindy Elkins-Tanton: Yes, Dawn was a fantastic precursor mission for us, because so much was learned about ion thrusters, which are close cousin to what we're flying, and also how to go into orbit around a small object and how do you stay in orbit and find stable orbits. Dawn was a ground breaker.

Sarah Al-Ahmed: Absolutely. I love that mission. I have a mission pin of it in our headquarters.

Lindy Elkins-Tanton: No, it's so nice.

Sarah Al-Ahmed: This young man came up to me while I was teaching a field trip at an observatory and he was 10 years old. He came up to me and he was like, "I am going to be a rich scientist someday." And I was like, "Oh, really? How are you going to accomplish that?" And he goes, "Have you heard of Psyche?" And I was like, "I've heard of Psyche."

Lindy Elkins-Tanton: Oh my gosh.

Sarah Al-Ahmed: And he goes, "Well, I want to start an asteroid mining company and then I want to use that stuff to build new computers and then take the money and fund more space exploration."

Lindy Elkins-Tanton: I love it.

Sarah Al-Ahmed: Not like I'm saying we should go mine Psyche. I mean, it's a very rare object. We should preserve it if we can, but I loved this kid's idea. He was so excited by Psyche to he had a whole plan.

Lindy Elkins-Tanton: This is just the most hilarious thing for me. Back in 2017, in January when I got the call from Thomas [inaudible 00:39:47] telling me that we were selected for flight, I more or less spent the next 24 hours being interviewed on the phone and I was out in a house in Western Massachusetts up in the Snowy Hills, and I was out there by myself as it happened. My husband was at a math conference and it was amazing, intense and fabulous day. And my neck was sore and it was really quite incredible. And PBS News Hour asked me, "How much would Psyche, if it's made of iron and nickel and copper and iridium and rainium and platinum and palladium and gold and silver, which it is, it'll have little pieces of all of that in the metal phase inevitably, how much would it be worth?" I thought, that's a fun calculation. So I just calculated, I can't remember if it was the iron and the nickel or just the iron, what it would sell for on the World Metals Market of 2017, and the answer was $10 quintillion. I mean, what does that even mean? It's many times the whole global economy. Of course, and they knew this, this is a fallacy at every level. First of all, we have absolutely no way to bring Psyche back ever. It's so far away and it's such a big object. I can't even imagine when in the future humans could even do it. And then if you brought it back, of course it would be worth nothing, because when you have a glut on the market, all the prices fall. I mean, everything about it is wrong, but it's fun to talk about. Of course, because there's a dollar sign in front of it, the whole world kind of went berserk. And we've had so many headlines about how Psyche's going to make us rich and it's gone... I mean, there's all kinds of absurdist things out there, which is actually kind of fun and it hasn't been too annoying. Even NASA headquarters hasn't been too annoyed. But it's very important to discriminate for everyone the fact that Psyche mission is a fundamental science mission. We're just going there to learn about our solar system. There's nothing about mining in it, and there's no money to be made. And so it is absolutely not a moneymaking trip or has nothing to do with mining except, because it'll be our very first look at a metal surface, it'll be very useful for mining companies that want to try to do this with near earth asteroids. Ones that are much smaller and closer to the earth. We cannot do it with Psyche. So Psyche at its closest is 240 million miles away. Mars by contrast gets as close as 32 million miles and Mars is pretty darn far away. We're not really thinking about bringing resources back to Earth from there and Psyche is so much farther. So concentrating on near earth asteroids in the future, I'm pretty confident we will have asteroid mining and that will be good for the earth. So that's nice.

Sarah Al-Ahmed: Yeah. And that brings up the idea of planetary defense as well, because it's one thing to say that we want to protect the earth and its creatures from asteroids and even comments hitting us, but it's a hard sell. It's a really catastrophic situation if it happens ever, but it's likelihood of happening in our lifetime's pretty rare. So if you add this financial incentive behind it, maybe we can mine these near earth asteroids for rare metals and things like that. Maybe we can help motivate people. We're still going to try here at The Planetary Society to get as many people in on planetary defense just for the sake of protecting our world. But that adds an additional thing to the calculation that could be useful.

Lindy Elkins-Tanton: Yeah. It's something that I appreciate actually about Jeff Bezos's vision. We can have a lot of criticism on a lot of levels, but this idea that we need to move our mining and resource operations off our precious earth and out to asteroids, I think is a real thing. We have got to save this earth for life, and mining is not in general a great thing for life on earth. So I'm all for it.

Sarah Al-Ahmed: Yeah. Although it does bring up, I don't know if you saw that movie, Don't Look Up, on Netflix. A bunch of my coworkers and I got invited to the pre-screening of that movie and in it the financial incentives around whether or not to deflect this object coming into earth come into play in a very large way.

Lindy Elkins-Tanton: And if it's a big enough object, you could get the world united and if it's a small object, there'd be a lot of different opinions, I think.

Sarah Al-Ahmed: That's wild. Who even knows what industries will build in space?

Lindy Elkins-Tanton: Yes. Exciting, motivating for kids. This is, I think, the best thing about space exploration, that instead of all these narratives we have around us of guilt and shame and fear, climate change and pollution and pandemics and poverty, we have this narrative of hope. Let's look out from the earth and do something altogether that can help our future.

Sarah Al-Ahmed: I mean, I know it played a big part for me growing up. Space was the thing that helped me get through the hard times in my life. And anytime something really impacts you, I could always just go outside and look up at the sky and think about who we are and how special it is that we're alive in all of this.

Lindy Elkins-Tanton: So right.

Sarah Al-Ahmed: Anytime a little kid comes up to me with their wild plans to asteroid mine, even if it's not how I'd do it, it's really exciting that that's where they're at right now.

Lindy Elkins-Tanton: I love that. I absolutely love that. And it's such a good point that you're making too, that just because it might not be how we would do it or that we think something isn't possible, it's not our job to pass on that negativity. We're all trained critics, especially academics like, "That's not right, because I know better," is kind of how we're taught. But what we need to be saying to the world is, "Give it a try. I'm behind you a 100%."

Sarah Al-Ahmed: Anything we can do to foster these kids' imagination, and I'm sure images of a straight-up heavy metal asteroid will do that.

Lindy Elkins-Tanton: I hope so. I hope it looks so weird. I have no idea. The worst possible outcome was that it looks really boring somehow. I don't know if that's even possible, but that's my nightmare.

Sarah Al-Ahmed: I'm sure, at least the spectro suggests, that it's got to have some open metal on the surface. It's got to be interesting, at least in some parts and I'm going to hold out hope and we'll know in just a few years, which is wild.

Lindy Elkins-Tanton: In just a few years we're going to know. We're all going to find out together, which is also what I love about this. It's for everybody on earth at once.

Sarah Al-Ahmed: Well, thanks for having this conversation with me, Lindy. I'm, I'm so excited for this mission and I hope this is given other people an opportunity to get as excited as I am, and I'm sure you are.

Lindy Elkins-Tanton: Well, Sarah, thank you so much for inviting me on. It was great to chat with you.

Sarah Al-Ahmed: Wonderful. And when it actually does reach Psyche and we learn all these amazing things, I would love if you'd be willing to come back on and tell us all about it.

Lindy Elkins-Tanton: I'd be thrilled, of course.

Sarah Al-Ahmed: I'm so grateful to have had a chance to speak with Lindy. Her life story and her passion for her work is absolutely inspiring. And if you can't tell, I'm already planning to make Psyche pictures my wallpapers on every device in my home. I'd also like to share a short update on something that we spoke of early on in the interview. As Lindy said, "The delay to the Psyche mission has deeply impacted one of NASA's upcoming missions to Venus Veritas." The mission is currently on an indefinite hold due to budget and workforce issues. The Planetary Society is already working to advocate for this mission. If you live in the United States, you can help. Visit our action center at and click on, Save the Veritas mission to Venus, to send a letter to your representatives in Congress. And less than a minute. Together we can try to get victory for Veritas. Now let's get an update on the night sky in what's up with Bruce Betts, the chief scientist of The Planetary Society. Hey Bruce.

Bruce Betts: Hey, Sarah. How you feeling?

Sarah Al-Ahmed: I'm doing so much better than I was a few weeks ago. Thanks for asking. And I keep getting messages from people all around the world still that are just like, make sure you take care of yourself. Make sure you get the rest, just very kind. So I'm really grateful.

Bruce Betts: That's nice.

Sarah Al-Ahmed: Yeah, but getting better all the time.

Bruce Betts: Good, good, good, good, good, good.

Sarah Al-Ahmed: So what's going on in the sky this week? I can actually go outside now. I'm out of quarantine.

Bruce Betts: Hey, congratulations. And it's occasionally clear here in between massive storms, so you'll be able to hopefully see over low in the west, super bright Venus, Jupiter getting lower and lower. It's getting tough. You have to see it shortly after sunset. But Venus looking spectacular, brightest star like object up there and then look up high, you can see Mars, which is much dimmer and reddish. Then for you pre-dawn folks, Saturn getting higher and higher over in the east actually becoming sort of easy to see now. Fairly bright looking yellowish and that's basically what we got going on.

Sarah Al-Ahmed: Yeah, I'm hoping there's a good moment in between the rainstorms in the next few days for me to go outside and actually see some stars and planets, because I miss the sky.

Bruce Betts: Onto this weekend's space history. You probably remember it was 1655 that Christian Hogans discovered Saturn's moon, Titan. With a moderate telescope, even a fairly small telescope, you can probably pick out Titan if it's on one part of its orbit away from Saturn. If you look at Saturn and look for a little dot off to the side, you can rediscover Titan for yourself. Onto... So geostationary satellites hang out in the same place over earth, about 36,000 kilometers above the surface of the earth. We point our TV dishes and communication satellites at them. They orbit at the same speed. So I thought, "Hey, what would an aerio stationary satellite be like, so orbiting Mars?" And turns out it's about half the altitude of a geostationary satellite. So the proper place to stick a spacecraft. So it's always looking at the same place in the sky from where you are on the surface. So you place it in the equatorial orbit and about 20,000 ish kilometers above the surface.

Sarah Al-Ahmed: That's really cool to know. I mean, someday people are going to need to know that information for satellite reasons actually.

Bruce Betts: True, and I'm sure they will probably check this show.

Sarah Al-Ahmed: Definitely.

Bruce Betts: Shall we go to the trivia contest?

Sarah Al-Ahmed: Let's do it.

Bruce Betts: I believe the question was, what science instrument on the Voyager spacecraft has a name whose acronym is also the name of a part of an eye, E-Y-E? How'd we do?

Sarah Al-Ahmed: We got a lot of really interesting answers. Many people actually send us in trivia bits from other sci-fi TV shows they thought was referencing this instrument. But the answer is Voyager's Iris. Which stands for Infrared Interferometer Spectrometer and Radiometer. Our winner is Marcel John Krigsman from Gouda Netherlands. So you're going to be winning Matt Kaplan's personal copy of a book called, Impact How Rocks From Space led to Life Culture and Donkey Kong, by Greg Brennecka. I feel like I should read this book. I mean, Donkey Kong, how did that come in there?

Bruce Betts: Got any more?

Sarah Al-Ahmed: Yeah, we got some really wonderful messages from people around the world. As I said, many people wrote to tell me that they want me to feel better, but I loved the number of jokes people writing me saying that I probably got COVID from Dalek's at the Dr Who convention.

Bruce Betts: They are so devious.

Sarah Al-Ahmed: Clearly an evil plan by Davros to give me COVID. So we'll have to talk to the new doctor about that. Also, I loved this Norman Cassoon from Banburyshire UK sent us this adorable photo of two of his dogs and said that they're looking forward to listening to the show before bedtime. And that Betsy Boo and Pixie Pony Love Planetary Radio, which I love.

Bruce Betts: Oh, that's hilarious. That's awesome. Please tell me they're like giant Mastiffs or Rottweilers.

Sarah Al-Ahmed: No, these they're cute little black pups with curly hair. I don't know what their doggy breed is, but they were very adorable.

Bruce Betts: All right, we'll move on to a new question. What do astronomers call a ring caused by gravitational lensing? So they look in a telescope image, they see a ring caused by gravitational lensing, what do they call it? There are actually a couple possible answers that will be considered correct. And so give me one official thing, not what just some astronomer calls it when he is really sleepy or she in the middle of the night. Go to and get your entry in.

Sarah Al-Ahmed: And you have until Wednesday, March 29th at 8:00 AM Pacific time to get us your answer and the winner this time will win another Planetary Society beanie to keep you warm. Also, I wanted to say happy Equinox to everyone. This next upcoming Monday is the Equinox. So everyone on the Northern Hemisphere have a happy spring and everyone in the Southern Hemisphere, happy autumn.

Bruce Betts: Nice. Happy Equinox everybody. All right, everybody go out there, look up the night sky and think about hummingbirds. Thank you and goodnight.

Sarah Al-Ahmed: We've reached the end of this week's episode of Planetary Radio, but we'll be back next week with more updates on the world of space science and exploration. Planetary Radio is produced by The Planetary Society in Pasadena, California, and is made possible by our asteroid enthused members. You can join us as we continue to support the missions that matter and learn more about our beautiful place in the cosmos at Mark Hilverda and Rae Paoletta are our associate producers. Andrew Lucas is our audio editor. Josh Doyle composed our theme, which was arranged and performed by Pieter Schlosser, and until next week, ad astra.