Planetary Radio • Nov 17, 2021

The DART asteroid impact mission begins, with Nancy Chabot

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Nancy Chabot

Planetary Chief Scientist at Johns Hopkins Applied Physics Lab, and Coordination Lead for DART

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Bruce Betts

Chief Scientist / LightSail Program Manager for The Planetary Society

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Mat Kaplan

Senior Communications Adviser and former Host of Planetary Radio for The Planetary Society

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Rae Paoletta

Director of Content & Engagement for The Planetary Society

DART coordination lead Nancy Chabot and the rest of the Double Asteroid Redirection Test team will see their spacecraft rocket toward asteroids Didymos and Dimorphos in a few days. She returns to Planetary Radio with a preview of the mission and its difficult challenge. Planetary Society editor Rae Paoletta takes us on a brief tour of the solar system’s volcanoes, and a special guest joins Bruce Betts and Mat Kaplan for What’s Up.

DART at the Didymos binary system
DART at the Didymos binary system This illustration of DART shows a view of the spacecraft from behind the NEXT-C ion engine.Image: NASA/Johns Hopkins APL

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Trivia Contest

This Week’s Question:

What telescope was used to discover Didymos, the companion to Dimorphos, the asteroid that DART will impact?

This Week’s Prize:

A Planetary Society KickAsteroid r-r-r-rubber asteroid!

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Complete the contest entry form at or write to us at [email protected] no later than Wednesday, November 24 at 8am Pacific Time. Be sure to include your name and mailing address.

Last week's question:

Who was the first Soviet cosmonaut to fly two orbital missions?


The winner will be revealed next week.

Question from the Nov. 3, 2021 space trivia contest:

Who was the first chimpanzee to orbit Earth?


Enos was the first and only chimpanzee to fly an orbital mission. He was also the third hominid in orbit, following Yuri Gagarin and Gherman Titov.

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Mat Kaplan caricature Illustration of Planetary Radio host Mat Kaplan by November 17, 2021 space trivia contest winner Agent Moeller.Image: Agent Moeller


Mat Kaplan: DART departs for a date with destiny this week on Planetary Radio. Too much alliteration? Welcome. I'm Mat Kaplan of The Planetary Society with more of the human adventure across our solar system and beyond. The launch window for the double asteroid redirection test mission opens shortly after 1:00 AM Eastern time on November 24th. Like all planetary science missions it has been a long time coming and is the work of many. Unlike any previous mission, it will attempt to change the course of a small asteroid by slamming into it at 6.6 kilometers per second, or 15,000 miles per hour. Demonstrating this capability might change the course of future history. Dark Coordination lead Nancy Chabot is back to prepare us for this journey. Jupiter's moon Io is impacted by asteroids, but you can rarely see the craters they leave. That's because it is constantly being resurfaced by volcanoes. And that's just one of the solar system's volcanic worlds that my colleague Rae Paoletta has written about. She'll join me in a couple of minutes.

Mat Kaplan: Down the line, Bruce Betts and I will introduce you to The Planetary Society member who outbid the competition in our recent auction. His dubious reward, joining Bruce and me on this week's What's Up. Turns out he's a bit of an aerospace pioneer. One of those ionic volcanoes can be seen blowing its top at the top of the November 12 Downlink, The Planetary Society's free weekly newsletter. Below it are these headlines, the crew two astronauts return to earth on November 9th, crew three headed to the International Space Station the very next day. NASA has admitted that a 2024 return to the moon by humans is not going to happen. They're now aiming for 2025 at the earliest. I've since heard that it could be two or three years later. Step lightly on those eggshell worlds. A new study describes some exoplanets as having ultra thin crusts, and no plate tectonics. Researchers believe they would not be likely places to find life and really, who would want to spend their life walking on eggshells?

Mat Kaplan: You'll always find the latest edition of the Downlink at And if you really want to stay up to the minute, check out our social media channels. Rae Paoletta is an editor for The Planetary Society. Rae, who doesn't love, I mean, unless you are from Pompei or Herculaneum, who doesn't love a great volcanic eruption, right?

Rae Paoletta: Oh, you, you absolutely have to love them. I mean, they're just amazing.

Mat Kaplan: I'm going to start where you ended with this November 11th, 2021 piece, which is titled Mind Blowing Pictures of the Solar System's Most Volcanic Worlds. It is a great collection of these fiery mountains all over the solar system. You started with our own planet, which you point out, no apologies needed, we're a planet in space. We have volcanoes.

Rae Paoletta: Exactly. I mean, I think that we have to give earth a little bit of credit, right? I mean, we are kind of in a way the ultimate volcano world. I mean, sure, we're not Io or we're not a world with cryo volcanoes exactly. But we do have some of the most impressive ones in the solar system. We've got about 1,300, 1,350 potentially, active of volcanoes on earth right now. I mean, we've got to give ourselves a little bit of credit there.

Mat Kaplan: Absolutely. Let's look elsewhere, and I'm going to start with this terrific infographic that was developed by our colleague at the society, Merc Boyan. Volcanoes of our Solar System, it's gorgeous to look at, and it's been getting lots of attention, but really what stands out for me is just how far ahead of every other volcano is Olympus Mons, at least in terms of height, if not activity.

Rae Paoletta: It's just a monster. I mean, it is super impressive to think that this is out there. I mean, I had definitely had a little bit of a mini existential crisis when Merc showed this to me at first. I was like, "What? How can anything be that large?"

Mat Kaplan: It's not that tall. Is it? Well, yeah, actually it is up there on the red planet. You cannot talk volcanoes in our solar system without going to Io, which is, I mean, come on, it's the volcano planet.

Rae Paoletta: It is the volcano planet. In fact, even NASA has said that it's the most volcanic body in our solar system. There's just so much going on here. In fact, I think there's more than 400 active volcanoes right now on Io or something. It's amazing.

Mat Kaplan: And it's a relatively small world. I've joked in the past that I would hate to be a cartographer specializing in Io, because the surface is constantly changing because of all the activity up there. But it's certainly not alone. You go through a number of other worlds, Venus, where I guess we know there are volcanoes, but we're still not quite sure whether they're active. What are the chances we're going to learn soon?

Rae Paoletta: So isn't that amazing to think about? This one's really interesting, people that follow my work know that I am a huge Venus fan by the way. So I hope I'm not giving away too much here, but I think it's really cool that we're going to get three Venus missions relatively soon. We're going to get VERITAS, EnVision, DAVINCI+. And I think that all three of those are going to give us some sort of insight into the volcanic activity on Venus. We've never actually seen it directly, directly imaging them, but I think that people are pretty confident that the activity is ongoing there.

Mat Kaplan: You also got Europa, you've got Enceladus. Can't leave those out. But I want to turn to the one that's the farthest out, at least in this collection, and that's Triton, where there are more of these so-called ice volcanoes or cryo volcanoes. It seems like a contradiction in terms.

Rae Paoletta: Yes, absolutely. It's funny. I think this is the one that I've gotten the most questions about. I even spoke about this with my mom. Hi mom, if you're listen to this, because she was so fascinated with Triton, and I think this one is super cool, no pun intended, because it's kind of like this icy world. And we really don't know that much about it. To me I feel like after I wrote this piece, I said to Jason, Jason Davis, the editor, by the way, my editorial director, he and I were speaking. I was like, "I think that the article kind of unintentionally advocates for more missions to the outer planets and the outer world." And I personally would love to see a Neptune and Uranus mission in my lifetime.

Mat Kaplan: Hey, anybody who listens to this show knows that we are entirely intentional about wanting more missions to those outer worlds. Uranus and Neptune. I'll just close with this. You didn't do this entirely on your own. You talked to some terrific researchers to get a lot of what you've shared with us.

Rae Paoletta: I spoke to some really incredible scientists who have done so much awesome work on some of these worlds. I mean, Julie Rathbun, Paul Burn, Caitlin Ahrens, just phenomenal, please follow them. They are super, super smart.

Mat Kaplan: Rae, thank you so much. Hey, Rae's mom, she did a good job, didn't she? As usual, Rae Paoletta is who we've been talking to. She is my colleague editor for The Planetary Society. You can read her piece at, just look for it among the articles it's dated November 11. Once again, mind blowing pictures of the solar system's most volcanic world's. Rae, if you ever visit one, don't get too close.

Rae Paoletta: I'll be sure to exercise caution.

Mat Kaplan: No need to write, Rae and I both know that Io is a moon, not a planet, really move away from the keyboard. We last talked with Nancy Chabot in the defenders of earth panel discussion that highlighted the 2021 planetary defense conference. She was joined in that May 12 episode by many other planetary defense all stars, including our own Bruce Betts and NASA's Kelly Fast, program manager for the Planetary Defense Coordination office. That office at the agency's headquarters has oversight of the double asteroid redirection test mission. You may have heard Casey Dreier talking to Lindley Johnson, head of the PDCO in the November 21 Planetary Radio Space Policy edition. The list of institutions that are contributing to DART is long and impressive. They are led by the Johns Hopkins University Applied Physics lab, where Nancy is also planetary chief scientist, and runs the meteorite lab. Nancy it is always a pleasure to talk to you on Planetary Radio, or anywhere else. Welcome back to the show.

Nancy Chabot: Great. I'm happy to be here again. I always like coming.

Mat Kaplan: I want to proudly tell you first off that I passed APLs planetary defender test just this morning, got my certificate and badges. And so I think congratulations are also due to me. You want to talk about that, this program that is offered for people to get involved in the mission?

Nancy Chabot: Yeah. Well, congratulations on becoming a planetary defender. We're very happy to have as many planetary defenders as we can get around the world. So yeah, it's a neat little quiz. You can go onto the DART website and take the quiz right there and you have to answer a few questions. And after that, there's a cool badge that you can put on your social media accounts and share with your family and friends. There's actually a certificate you can print out that'll have your name and the date that you passed on it. I've taken the test multiple times myself and I have passed as well.

Mat Kaplan: I'm glad, I'm sure you aced it. I did the same and I'd have been very embarrassed in front of my colleagues if I hadn't, since Planetary Defense is a pretty important priority for all of us at The Planetary Society, which of course is why we continue to be so excited about DART. It must be just almost overwhelmingly exciting for you and the whole team at APL and elsewhere. What is the current status of the spacecraft? Are you go for launch from Vandenberg Air Force Base?

Nancy Chabot: It is a really exciting time for our full team. And it's a privilege to be here talking on behalf of the team, which is international and around the world. A lot of people have worked to make this first planetary defense asteroid deflection mission happen. It's been a long time in the coming and yeah, go for launch. The launch period opens on November 23rd, Pacific time. And so we are on track and ready for that launch.

Mat Kaplan: There are a lot of us who plan to be up and watching that launch, along with you, where are you going to be?

Nancy Chabot: I'll be out in California at Vandenberg Space Force Base watching it there. From the trajectory, it does sound like if the weather cooperates that along the Southern coast of California, people will be able to look up into the skies and see it as well. So we'll have more details on that as it gets closer I'm sure.

Mat Kaplan: Well, that's a gift that everybody in Southern California can thank you for. Those contrails or the exhaust from those rockets taking off from Vandenberg often put on quite a show over down, even as far as San Diego where I am. For those, that handful of listeners in the audience for this show who may not have heard of it. Could you give us the thumbnail description of the mission, what you're setting out to do?

Nancy Chabot: Sure. The Double Asteroid Redirection Test mission, DART for short is a NASA mission that is focused on planetary defense. And in particular, it's going to demonstrate how you might deflect an asteroid in the future if you needed to to keep it from hitting the earth. This is just a test. That's what the T in dart for, these asteroids are not a threat to the earth, but this makes it a perfect system in order to go crash the spacecraft into this asteroid, give it a small nudge. It's just about deflection, not disruption. We're not trying to destroy this asteroid, just give it a small nudge that adds up to a big change in its position in time. And this is what you would do if you wanted to avoid asteroid and earth being on a collision course in the future potentially.

Mat Kaplan: And that D for double is a pretty significant part of the name of this mission as well. Because we're going to, you said, it's a system, right?

Nancy Chabot: Yeah. The double asteroid is really enabling for this DART mission. There's two asteroids. There's the larger asteroid Didymos, and it has a small moon asteroid Dimorphos that goes around it every 11 hours and 55 minutes. It was discovered from telescopes here on the earth, and telescopes on the earth have been looking at it for decades. And so we know a lot about how this system works. And what this allows us to do is we know the system ahead of time, the DART spacecraft will come speeding in really fast, 15,000 miles per hour, and run into Dimorphos, the smaller moon. And it's just going to change how it goes around the larger asteroid by about 1%. And then we'll use the telescopes here on the earth to figure out how much we deflected this asteroid again.

Mat Kaplan: 15,000 miles per hour, which I happen to know is about 6.6 kilometers or 4.1 miles per second. I know that because it was Bruce Bett's random space fact in last week's episode of Planetary Radio. Tell us about DART's one and only instrument, and its heritage as well, because I think it's a part of how you've been able to pull off this mission relatively cheaply.

Nancy Chabot: Yeah, there's one camera on board the main DART spacecraft. It's called DRACO. And it is based on the design of the LORRI instrument that took spectacular images of Pluto and Arrokoth on the New Horizons mission. And so using that same similar camera telescope design is what we're using here for DART.

Mat Kaplan: I was actually surprised to see how many other technologies, some of the new technologies are along for the ride on DART from its engine to its solar panels. Can you talk a little bit about some of those?

Nancy Chabot: Yeah. I can talk a lot about the new technologies on there, because there are quite a few of them. Some of the most obvious ones might be the rollout solar arrays. So these arrays, when they are launched are rolled up sort of like rolls of tinfoil and they're really lightweight material. And then they're going to roll out in space and they're going to extend quite a distance, 18 meters tip to tip. And so this is really kind of a new technology that's been demonstrated on the space station, but this will be the first spacecraft to use those rollout solar arrays. We also have the next sea ion propulsion engine, which is a more powerful ion engine that has been flown on other NASA missions. So we're just using this to demonstrate it's in flight capabilities, but it could be very enabling for future missions, but I'd have to say that our number one technology for DART is smart nav.

Mat Kaplan: Which is how you're going to pull off this, I don't know. How would you describe it? It seems like sort of hitting a golf ball with a BB or something like that.

Nancy Chabot: Yeah. So the spacecraft is going really fast. And it's actually targeting a small asteroid. The asteroid is only 116 meters in diameter, less than two football fields. So one hour ahead of time, you are 15,000 miles away from something that's the size that's smaller than two football fields. And you have to make sure that your spacecraft goes and hits that smaller object. The other complication is this double asteroid system. There's the two asteroids, and actually you can't resolve the difference even using Draco, this amazing telescope that's based off the ones that took pictures of Pluto and things like that. Even using that great camera that we have, you can't actually tell the difference in those images between Didymos and Dimorphos until the last hour of the mission. So before that they're in the same pixel. And so in the last hour you have to ensure that the spacecraft going very fast hits this 160 meter Dimorphos asteroid, and that's all done on board.

Nancy Chabot: You can't have humans in the loop because of this small timeframe and what you're talking about. So the images will get it taken by Draco. They'll be interpreted on board by the smart nav system and the algorithms. And those will be used to control the thruster firing of the spacecraft to ensure that you impact into Dimorphos and not Didymos or miss altogether. One of the other challenges with this is we don't actually know what dimorphos looks like. We've never seen it before. We know asteroids have all sorts of weird shapes. So we've been doing extensive testing. The DART team has done extensive testing using all sorts of different asteroid shapes and sizes and how things might be illuminated because this is an imager, a visible imager that's going to be used in order to do this interpretation. And all of that is feeding into smart nav being able to target a small asteroid. And targeting small asteroids is something that you would want to do if you were doing a planetary defense mission to protect the earth in the future.

Mat Kaplan: So this makes me wonder if you and the team are taking into account what we have learned from just recent asteroid missions, like Hayabusa 2 OSIRIS REx, have they had any effect on your planning and the programming that's going in so that DART can handle this on its own?

Nancy Chabot: Hayabusa 2 two OSIRUS REx, every mission that goes to asteroids tells us new information about these bodies, which is incredibly useful for science, understanding how the solar system formed, how did it evolve, what it was like billions of years ago, but is also really relevant to the present and the future for planetary defense, protecting the earth from these objects going forward. Those information that we've gotten from those two missions have been incredibly valuable. I wouldn't say that they have changed anything about our plan for DART, but definitely we will be taking the knowledge that we gained from DART and putting it in the context of all of these asteroids, because this is really just the first step. DART is just the start of planetary defense and how you would apply this to asteroids in the future will be exciting work to go.

Mat Kaplan: Casey Dreier my colleague, our chief advocate senior space policy advisor, he does the monthly space policy edition of Planetary Radio with me and his guest on the November show was Lindley Johnson who you know well, NASA's planetary defense officer, leader of the Planetary Defense Coordination office, which is overseeing the dark mission at NASA headquarters. I believe, I don't think you'll be surprised to hear that Lindley speaks glowingly and with great anticipation about the dark mission and about the pioneering role that this mission is going to fulfill if all goes well. I mean really, while we have touched asteroids before, and we even slammed into a comet once years ago with Deep Impact, this is really the first time we're doing something like this, isn't it?

Nancy Chabot: It really is. I mean, DART is a pioneering planetary defense mission, a mission focused on planetary defense objectives. Like you said, it's the first one that's being launched out of NASA's planetary defense coordination office, which was only stood up in 2016. And so it really is setting the stage for things to come forward. We're really happy to have LICIACube on here. The CubeSat contributed by the Italian space agency, and we're really happy to have ISA's HERA mission that's going to follow up on DART and get there in 2026, also a dedicated planetary defense mission in many ways to see the crater made by DART in Dimorphos and to get the mass of Dimorphos. And I think this all underlines that DART really is just the start, that DART really is pioneering the way for these future planetary defense missions and investigations to go so that if we needed to prevent asteroids from hitting the earth in the future, that we might have the capability to do that.

Mat Kaplan: I'm so glad that you mentioned that little CubeSat that DART is going to carry along on, on its journey from the Italian space agency. Can you talk about how it's going to be a witness to this cosmic impact?

Nancy Chabot: Yeah. LICIACube is an incredibly capable, small little CubeSat on its own. And so it will get kicked off of the main dart spacecraft about 10 days in advance of DART's collision with the asteroid. And that'll give it enough time to get out of the way so that it also won't collide with the asteroid. It will get spectacular images of DART's collision and then it'll make its closest fly by of Dimorphos roughly three minutes after DART's collision and get really great images of the ejecta and how that's formed. We there's likely going to be too much ejecta to really see the surface and see the crater that DART created at that time. But we'll see what those images show. And LUCIACube will just keep on its path. And those images will actually take a little while to get back down. They'll take a few weeks after DART's collision before we'll have all of those, but it really is a great addition.

Nancy Chabot: And I think all of this just underlines that planetary defense is a global concern. And so international cooperation for this international issue is key. So we're really happy to be collaborating with the Italian space agency and having the European space agency following on with HERA and all of this moving forward into a world where there are future planetary defense missions. And we continue to advance these capabilities,

Mat Kaplan: Something that just occurred to me. I remember when we were looking forward to getting those images from that long ago impact or deep impact. You couldn't really see that much because the explosion made such a big flash and all kinds of ejecta. Is that one of the reasons this little CubeSat is going to delay its imaging or are there other reasons for that? I'm sure people have thought about how deep impact did its job.

Nancy Chabot: Yeah. Being able to measure the ejecta and what the ejecta looks like is one of the main goals for LICIACube. And you want to give that a little time to evolve in order to see how the ejecta has come out from the DART impact. And all of that was taken into account with the timing of its fly by. Though you won't be able to see the surface, seeing the ejecta is very important. This is what gives the asteroid the extra push. This momentum enhancement factor that we talk about so much. The DART spacecraft will come in and it will impart its momentum and be destroyed when it hits the asteroid. But we really suspect that the amount of objective that's created is going to be substantial. And it's going to be sort of like a little jet that pushes in the opposite direction and even deflects the asteroid even more. How much that is, is one of the main reasons to do this real test on our real asteroid of a relevant size.

Mat Kaplan: Isaac Newton would be so proud. We do have a lot still to learn about space rocks, don't we? And I mean, that's in spite of other missions that are underway and getting underway, I'm thinking of Lucy and Psyche. And just a couple of weeks ago, we were talking with Sarah Al Amiri of the United Arab Emirates about the very ambitious asteroid mission that they're taking on. You've got to be happy to see all this. And I believe I'm right. We have a lot to learn, don't we?

Nancy Chabot: We do have a lot to learn and it is really exciting. I think all of us in the field of planetary science and in planetary defense encourages many missions as possible to try to investigate these really unique objects. A lot of times, I think sometimes we do it a disservice by just referring to them all as asteroids or small bodies, because they're all so different. They tell you very different things about the formation of the solar system, the evolution of the solar system. And they have different implications for planetary defense as well, depending on their size, their composition, how they're put together. And all of these are important factors. So going to this wide range of diversity is a treasure trove for science, but it's also really important to get a handle on the extremes that you might be dealing with for planetary defense.

Mat Kaplan: Do you think we're going to have to smack into some more asteroids in the future as we learn how to keep them from smacking into earth?

Nancy Chabot: I do think that future asteroid mitigation missions will be necessary. DART is all about deflection, giving a small nudge, not disruption, not destroying it, and that's one capability. And given the DART results, we might want to follow up with getting better at asteroid deflection through a kinetic impacter, this event that happens that's a one time thing and is very energetic. There's other ways for planetary defense that people are considering as well, more of these slow push methods, if you will, which are not just this one event that happens, but where you work to move the asteroid slowly over long periods of time through using ion beams, for example, to focus on the surface or a gravity tractor where you kind of just hover near it and the force of gravity X, all of these though share one thing that unites planetary defense in any mitigation capability. And that is find the asteroids early. This is really the key for planetary defense.

Nancy Chabot: So sometimes it can seem a little glamorous to talk about deflecting asteroids or these other ways that you might mitigate them. But really underpinning planetary defense is finding the asteroids, identifying them, characterizing them, tracking them, giving yourself as much warning time as possible. All of the mitigation techniques are better served with that warning time.

Mat Kaplan: So are you looking forward to the launch of Neo Surveyor, that infrared space telescope that we've all been talking about for so long?

Nancy Chabot: I am very much looking forward to the launch of NEO Surveyor. I could not be more pleased. I think that's on track for 2026, and just waiting for it to get up there. That's been a huge priority for planetary defense for a very long time, many, many years. And so it's great to see NASA funding that mission and having it on track to be doing what it needs to do in 2026. A space-based telescope is the best way in order to identify the asteroids. That might be a threat to the earth.

Mat Kaplan: When Nancy Chabot and I return, we'll talk more about DART and some of the other missions of discovery she is working on.

Sarah: From missions arriving at Mars to new frontiers in human space flight, 2021 has been an exciting year for space science and exploration. Hi, I'm Sarah, digital community manager for The Planetary Society. What were your favorite moments? You can cast your vote right now at, and help choose the year's best space images, mission milestones, memes, and more. That's Thanks.

Mat Kaplan: When was your last trip to Antarctica?

Nancy Chabot: My last trip to Antarctica was in 2005.

Mat Kaplan: Oh, it's been a while.

Nancy Chabot: A while ago. Yeah. Kind of feels like a different lifetime almost, but yeah, before I got the job here at the applied physics lab. I was going to Antarctica pretty frequently.

Mat Kaplan: Isn't that because of your interest in these rocks that fall from space, although in this case, the little ones that you can find on the ice up there, or down there?

Nancy Chabot: Yeah. I like to say that earth getting hit by things is not all bad. I love meteorites. They are free sample returns, they are free samples from space, rocks from space that you can hold in your hand. And they just come to us naturally. And all we have to do is go and pick them up and find them and the capabilities that we have of studying meteorites in the lab down to literally the atomic scale now these days to learn about our solar system, there's actually meteorites contained pieces that predate our solar system. They're from other star systems. So literally by studying meteorites, we're learning about our solar system and beyond, we're learning how they went from these primitive materials to evolved materials that had cores and mantles and crust and vulcanism and all of these processes. So I could talk all day about how valuable meteorites are and how these things hitting the earth are actually quite beneficial and not a concern.

Mat Kaplan: I am with you. I am looking at the box that contains sitting in a little bed of red sand from the Sahara, the iron meteorite that was given to me by a friend ages ago who found it out there in the middle of the desert. So I have even more reason to be looking forward to the Psyche mission. You are in fact, a fellow of the, I hope I pronounce this correctly, the Meteoritical Society. And I saw that you were named its vice president. Now that was in 2020. Are you still in that position?

Nancy Chabot: I am. So I started that in January of 2020. I will be vice president for 2020 and 2021. And then I will become president in 2022 and 2023. Past president for two years after that. For me, this is a great honor to be serving in this position. Meteorical Society is a scientific community that's very international, brings together scientists and collectors from around the world who work on meteorites. And it's been kind of like family. It's one of the first conferences I went to in grad school. When I started working in this field, when I first got into planetary science. And it's been a lot of the colleagues that I've been down to Antarctica with when I've gone five different times, and who our paths continue to cross as we do our science to this day. And so it's really just a privilege to be serving into a leadership position for this great society.

Mat Kaplan: You are sure staying busy. Tell us about MEGANE, which I think you helped me before we started to record to pronounce that correctly. You're listed as the deputy PI for one of the instruments that will be on that Mars moon explorer, Mars moon exploration. MMX mission that Japan is preparing right now.

Nancy Chabot: Yeah. The MARSHA moon exploration mission from the Japanese Space Agency is an exciting mission because it's dedicated to studying the MARSHA moons Phobos and Deimos. Other missions have tried to be dedicated to studying these MARSHA moons, but haven't ever succeeded in the past. And so it's going to be very exciting to have missions dedicated to that. So MEGANE is the Mars moon exploration and gamma rays and neutrons instrument. It's a gamma ray and neutron spectrometer. It's being built at APL. There's a similar one that's going on Psyche, for example, on the Psyche mission 2 instrument, what it does is it determines the composition of these moons. We don't know how these moons formed, which is kind of a really cool question just in itself. These are the only other inner solar system moons besides our own. And we literally don't know how they formed, but the theories predict very different compositions, whether they're captured asteroids or whether they're pieces of Mars that were blasted off the surface.

Nancy Chabot: So getting the composition is going to be key for distinguishing between these different theories, but I should add that MMX mission is bringing back a sample of Phobos too. So that's going to be really exciting. So we'll have the global context from the Ghana, the Gamma ray and neutron spectrometer that we're building, but that'll really provide the context for the sample that comes back to these earth laboratories. And everything I was so excited talking about with meteorites is the same thing that you get to do with these samples when they come back and bring them into laboratories around the world to get the best possible information now, but then also in the future. I mean, Apollo samples remain heavily studied by the scientific community. As analysis and laboratory techniques advance over the years you can go back to these samples and continue to get new information about them. So I'm just delighted to be contributing to the MMX mission.

Mat Kaplan: Are you one of those who is hoping that maybe one or two of those rocks that MMX might collect and that you might point MEGANE at before they're collected might have come up from the surface of Mars itself. In other words, we'd have Mars sample returned years before we get a mission to accomplish that down to the surface.

Nancy Chabot: Yeah probably rock size is the wrong way to think about it. I think that samples from Mars that people predict might be there might be smaller on the grain size. And the samples that MMX is bringing back is kind of not like multiple rocks. You should sort of think of it as the Hayabusa 2 sort of sample sizes. But we do think that because earth laboratories can look at things on a grain by grain scale and even smaller, that there very likely are pieces of Mars in those samples on the MARSHA moons. And so we're looking forward to seeing that. That scale will be much too small for MEGANE . So what MEGANE would see instead is going to be a mixture.

Nancy Chabot: And so it'd look maybe like there was an asteroid material and some bulk Mars material and what those would look like when it was a mixture, but we won't be able to resolve different components like that. You'll need the sample to do that. But the global context from the whole moon, for the composition versus just the composition of your much, much smaller sample from just a given site on the moon will bring the whole system together and let us understand how these moons came to be.

Mat Kaplan: Very much looking forward to that mission, and to ISA and Jackson's BepiColombo mission that is already out there, of course, on its way to Mercury, a planet that you studied as part of the Messenger team some years ago, what's your role for BepiColombo?

Nancy Chabot: On BepiColumbo, I'm also really happy to be an interdisciplinary scientist. So I'm on the science team. My focus is a lot on the polar regions in particularly on the ice deposits that are found both near Mercury's north and south poles within these permanently shadowed regions. These craters that never see direct sunlight where we've seen evidence of ice. Messenger was the first mission I got the opportunity to work on, and I have such fond memories of that spacecraft and how long it lasted and the team and everything that we accomplished together, creating the first global map of this planet and seeing things that I had never seen before. Messenger's orbit was really elliptical. So it passed close to the north and far from the south pole. And so I've really been a lot of us, not just me, really want to see the south pole in much, much more detail. And BepiColombo is an orbit that's going to enable that.

Nancy Chabot: And actually the largest crater on the whole planet of mercury with the largest amount of ice in it is Chao Meng-Fu. And it's like right at the south pole. And I cannot wait to see BepiColumbo measurements of this crater.

Mat Kaplan: Can't help but think of the comparison to our own moon and the ice that we've discovered at the poles there for the same reason, those permanently shattered areas. Sounds like you expect something pretty similar.

Nancy Chabot: Actually on mercury, there is a lot more ice than on the moon. It's actually super interesting that way. Yeah. And we even know from Arecibo actually did a lot of great radar measurements of both poles and just very strong signals of these extensive water ice deposits and the messenger data supported that, but the amount of ice water ice that you have at mercury's poles, it's substantially more than we're seeing at the moon. Now the parts at the moon are still significant and still potentially very useful, especially for human exploration, but why moon and mercury have such different inventories of water ice is really an interesting question of itself.

Mat Kaplan: You know, I wasn't thinking of bringing up Arecibo, but since you have brought up it's amazing radar, well, what were its amazing radar capabilities. And of course it had this wonderful role in characterizing asteroids as well, using that powerful radar. I wonder if you are lamenting its loss and hoping that we can find a replacement.

Nancy Chabot: Yeah. The whole community is lamenting its loss, and mourning its loss. The contributions that it made to science were incredible. The contributions that it made to our community were incredible, and everybody is still very much reeling from this loss. I do think, especially for planetary defense, that planetary radar has a very important role to play in order for understanding the orbits of these objects. And so I do think that it makes sense to consider going forward, ways that we might be able to regain these capabilities. I am not a planetary radar expert, so I will not try to claim that I understand the best course of action forward, but we do have a huge gap in our knowledge and capabilities that would be great to fill.

Mat Kaplan: Here, here. I got just one more for you. And it's about a relatively new title that you've gained. I mentioned it at the top of the show when I was introducing you. New to me anyway, although you said it's a couple years old now, planetary chief scientist for the Applied Physics Lab. What does that job entail?

Nancy Chabot: Planetary science at APL has really grown in the last 20 years. I mean, near sort of set the stage for planetary science at APL, the first mission to rendezvous with an asteroid. And then followed on with Messenger and New Horizons to Pluto. And these missions that we've talked about. So as planetary chief scientist, it's great to be in this position where we get to sort of see what we're doing now and see what we should be doing in the future. So it's sort of a future looking position in a lot of ways to try to guide and position so that we can continue to make these contributions, which push the field of planetary science forward using our capabilities at APL to enable that.

Mat Kaplan: I bet that it also allows you to work with a lot of young scientists, young engineers, as you once were yourself, and help them toward the careers. The promise that lies ahead of them.

Nancy Chabot: That is one of the really rewarding things about being in this chief scientist position is being able to mentor earlier career scientists that we have at APL and outside of APL and sort of continue everything that we've built so far into these future generations. These missions take lifetimes literally sometimes to see them from an idea and a spark in order to full implementation. And so building up the community at APL and outside of APL is very important for all of us. And I know I feel very proud to be part of the planetary science community internationally, and as well as like funded by NASA. And it's great to see everybody so devoted to continuing all of the things that we have to explore in our solar system.

Mat Kaplan: Nancy, I think I can safely say on behalf of myself and all of us at The Planetary Society and everybody listening to this show, we cannot wait to see that rocket climb into the sky and put DART on its way and how much we look forward to that big bang, that somewhat smaller big bang that you hope to generate out there at the asteroid. Best of success with the DART mission.

Nancy Chabot: Oh, well thank you so much. The whole team is looking forward to it and we're looking forward to sharing it with the world.

Mat Kaplan: Time for a rather special edition of What's Up on Planetary Radio. We are as always joined by the chief scientist of The Planetary Society. That's Bruce Betts. Welcome back.

Bruce Betts: Thanks. Good to be back.

Mat Kaplan: But we are also joined by a special guest Arnie Grot is here with us in the session. Welcome Arnie.

Arnie Grot: Oh, it's great to be here Mat, and especially with Bruce, because I once took a class with him. Well, not with him, from him when he was associate professor and he taught Astronomy 101, and I audit that course, I didn't have to take the test, but being a past physicist and engineer, I was happy not to do that.

Mat Kaplan: I'm curious. Did you catch the very best of the lectures that Bruce would give each semester? The one that I was also on?

Arnie Grot: Yeah, those were, they were fun things, and I wouldn't say they were best, but they were good entertainment as well as getting a lot of facts in them.

Mat Kaplan: Good answer. Good answer.

Bruce Betts: Yeah. Well maybe I won't ever have Mat on again if I teach it again. Anyway, people can still watch the archives of those at, B-E-T-T-S. Thanks for taking the class, Arnie, and thanks for being here with us today.

Mat Kaplan: Where are you? It looks like you're at home.

Arnie Grot: Well, I'm at home, and I live in Connecticut, and I'm in my basement. That's where my office is. I'm in a multi-generation family. I got my two daughters and three grandsons and son-in-law, as well as my wife. So we enjoy it, togetherness.

Mat Kaplan: I was in Connecticut only what is it now about three weeks ago at my sister-in-law's house up in rural Connecticut. And man, are you fortunate to live in a beautiful place. You were also very fortunate. You were telling us before we started recording, you have ridden on the fabled Vomit Comet, the original one.

Arnie Grot: Well, yes, I worked for Pratt & Whitney. I'm a materials engineer with an MS from the university of Tennessee. I got my aeronautical engineering degree from Purdue University back in the late 70s. I was working in castings and solidification, single crystals and Marshall Space Flight Center was interested in that. I made samples for them. Later on they invited me to join them for a week of flights on the Vomit Comet or the KC135, which is out of Ellington Air Force Base, which is right next to the Johnson Space Flight Center. And so I did flights that day. One of the days, they were doing a video with a bullfrog from Louisiana because they had teachers from Louisiana flying, and Brewster Shaw, one of the astronauts was filming with them. So it was a fun weekend to get your ups and downs.

Mat Kaplan: Bruce, we have a connection to Purdue don't we?

Bruce Betts: We have a very strong connection to Purdue. Dave Spencer is a professor there, was, he's now JPL as our project manager and Justin Mansel got his PhD partially working with light cell two data and is still providing critical work as a visiting professor there at Purdue. So light cell two, heavily influenced and affected by the strong Purdue situation. And we have one of our two currently operating ground station tracking stations for light cell two is at Purdue.

Arnie Grot: Well, I remember watching the deployment and the unfolding online and seeing Bruce there and the Purdue people. So that was a fun thing.

Mat Kaplan: Arnie, we should say while it's delightful to have you here, regardless of why you're here, the why is pretty significant as well. You had the winning bid in the recent auction that The Planetary Society conducted. I'm sure this was the grand prize, getting to spend these few minutes during What's Up with Bruce and me. So thank you for your support.

Arnie Grot: You're welcome. My pleasure. I enjoy The Planetary Society and of course the chance to meet Bruce after all these years. Because I always watched his random space talks.

Bruce Betts: Sorry to disappoint you in person, but oh well.

Mat Kaplan: You can redeem yourself, Bruce, by telling us about the night sky.

Bruce Betts: I'll try Mat. Nice segue by the way. We've got a almost total lunar eclipse occurring this Thursday and the Friday night November 18th and 19th. It is over 97 per cent total. So there's a little sliver of the moon, not in the earth's shadow that's sort of centered over the mid Pacific, so visible in North America, but also in Japan, Australia, New Zealand will see parts of it. So it's a good time. And we'll hear in a moment about the oddity of being such a almost total eclipse.

Arnie Grot: Oh, I was just saying, I was hoping I can wake up. I normally do between three and 5:00 AM so I can watch it out here on the east coast at that time. And it's not cloudy.

Mat Kaplan: Yeah. Clear skies.

Bruce Betts: So I should say the greatest eclipse is at 9:03 UTC on the 19th. That's 1:03 Pacific standard time, 4:03 AM Eastern standard time. And that's when it'll be most in eclipse. We've also still got bright planets hanging out in the south and the west in the early evening, going from low down on the horizon, we've got Venus looking super bright, Saturn looking kind of yellowish, Jupiter looking bright to their upper left. Beautiful, beautiful view. We move on to this week in space history. It was 1969 that Apollo 12, the second batch of humans landed on the moon. And it was 1970 this week that the Soviets landed Lunokhod 1, the first wheeled vehicle successfully roving on the moon robotically operated in this case.

Arnie Grot: Well, Bruce, can you share any random space facts with us today? Something I would like to hear?

Bruce Betts: Well, I can certainly share a random space fact. And it ties to this eclipse. Because it's almost total and because the moon is near apogee so moving the slowest, it has these strange achievements of being the within a thousand year period, the longest partial eclipse that will exist in the umbral phase, the dark shadow phase will be the longest partial umbral eclipse of this century. So that'll be the penumbral eclipse, the whole partial shadow, the whole thing, six hours and two minutes, the umbral phase, which is easier to see by far three and a half hours, roughly. And that's the odd ditty about this week's solar eclipse. Let's try that again. Lunar eclipse. Sorry.

Mat Kaplan: Arnie, you've got to be happy with that one.

Arnie Grot: Well, I was happy.

Bruce Betts: Well, that's what matters.

Mat Kaplan: Let's go on the contest.

Bruce Betts: We asked you who was the only chimpanzee to orbit the earth? How'd we do, Mat?

Mat Kaplan: First Arnie, do you want to take a guess? Do you have any idea?

Arnie Grot: Well, I know Ham was the first one, but I'm trying to think. I should know because I read some of these things about it, but things go out of my head. Too many facts. Who was the first here?

Mat Kaplan: I'm not going to tell you. I'm going to let Dave Fairchild, our poet laureate in Kansas tell you Ham became the hominid, the first flew up on high. Enos followed after with two orbits in the sky, 18 kilograms in weight, he clocked in lots of hours, training for his Atlas fight from NASA's launching towers.

Bruce Betts: That is correct. Enos was indeed the first chimp to orbit the earth. Although Ham was the first suborbital chimp, Enos was the only orbital chimp. And the third hominid to orbit the earth.

Mat Kaplan: Which we also heard from a lot of people who entered this contest that the first hominids were not chimps. They were human types, Eureka Garen, and Garmin Tedoff. Our winner, and I am very glad to announce this, because he's a longtime listener, first time winner is my Michael Mueller. Michael, who is in the same region I'm in, the San Diego area of California. And he also sometime ago contributed what I thought was a pretty entertaining caricature of yours truly. Didn't help him win, obviously, because he's been waiting a long time. But congratulations, Michael. He indeed said that it's Enos, who was that first chimp to go into orbit. Michael, we are going to be sending you, I got it wrong when I announced this two weeks ago, it's not a Blue Shift Aerospace t-shirt, it's a Blue Shift Aerospace coffee mug. And after all, don't we all have enough t-shirts, but you never have enough coffee mugs, right Bruce?

Bruce Betts: Sure, Mat.

Mat Kaplan: Also, their mission patch from their successful flight of their very green rocket that they launched on the coast of Maine and New England, and a patch for the company itself, Blue Shift Aerospace, fresh Maine rockets is one of their slogans. Edwin King in the UK said that all this happened on November 29th, 1961. Enos was supposed to fly three orbits, but there was a malfunction of a machine designed to give him electric shocks. And that among other problems is why the mission was ended after two orbits. It also sets up reading this poem from Gene Lewin in the state of Washington to pave the way for mortal man, Enos sat in place aboard the Mercury Atlas five. Now part of the space race, a simulated crewman was trained to act as one, shockingly, orbiting our earth twice. Surely glad when it was done. It's true. I checked it out. They actually had a device that was supposed to give him shocks, but it was giving him too many shocks.

Bruce Betts: Oh gosh.

Mat Kaplan: And that was one reason, yeah. Isn't that swell?

Bruce Betts: Humans.

Mat Kaplan: Jason Gillett in Ohio agrees with you. He says, "I always have a hard time considering the non-humans we sent into space. They suffered a lot of stress or didn't make it back." He says he's glad to hear about Enos though. Courtney Katz in Pennsylvania, she learned about Enos from Mary Roach's book Hacking For Mars, which of course we talked to Mary about in one of the most fun episodes of Planetary Radio ever. And finally back to Ohio for our last contribution today from Jerry Robinette. He says, "How has Enos the space champ never become a Saturday morning cartoon? I would totally binge on that." And he adds, "Keep up the good work." And so Arnie, I guess he's talking to you. Bruce, do you have a new one for us?

Bruce Betts: Yes. Oddly enough, I do this time. DART headed off to the binary asteroid system with the larger asteroid being Didymos, what telescope discovered Didymos? What telescope was used to discover Didymos? Go to

Mat Kaplan: You have until Wednesday, November 24, the day before Thanksgiving here in the United States at 8:00 AM Pacific time on that day to get us this answer and win yourself a Planetary Society kick asteroid rubber asteroid. I believe if we're done. Arnie, thank you for joining us.

Arnie Grot: You're welcome. It was my pleasure.

Mat Kaplan: Once again, thank you for your support. Bruce, take us out.

Bruce Betts: All right, first, thank you Arnie. We really appreciate your support. And everybody else, go out there, look up at the night sky and think about what a caricature of Mat would look like, and what you would emphasize. Thank you. And goodnight.

Mat Kaplan: They may not have to look farther than this week's show page at, because we'll try and upload it there. That was Bruce Betts, the chief scientist of Planetary Society joined by Arnie Grot, scientist, engineer, and supporter of The Planetary Society. Thank you both, guys. Planetary Radio is produced by The Planetary Society in Pasadena, California, and is made possible by its members who are helping us make a deep impact. You can help change the course of history at Mark Hilverda and Jason Davis are our associate producers. Josh Doyle composed our theme, which is arranged and performed by Pieter Schlosser. Ad astra.