Planetary Radio • Nov 02, 2022

DART smacked an asteroid! So what’s next in planetary defense?

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On This Episode

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Lindley Johnson

Planetary Defense Officer for NASA

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Kelly Fast

Near-Earth Object Observations Program Manager for NASA Planetary Defense Coordination Office

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Sarah Al-Ahmed

Planetary Radio Host and Producer for The Planetary Society

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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

The success of the Double Asteroid Redirection Test was just one more step toward protecting our world from wayward asteroids and comets. NASA Planetary Defense Officer Lindley Johnson, and Kelly Fast, the agency’s near-Earth object observation program manager, return to our show for a discussion of where we go from here. Sarah Al-Ahmed will tell us about an article that locates the water on and under Mars, while Bruce Betts gets us ready to enjoy the upcoming total lunar eclipse.

DART's last complete look at Dimorphos
DART's last complete look at Dimorphos In a thrilling moment, DART captured this view of Dimorphos just as it was about to crash into the asteroid moon. Seconds later, the transmission ended.Image: NASA/Johns Hopkins APL
One of LICIACube's stunning views of DART's impact
One of LICIACube's stunning views of DART's impact This image, released on Sept. 27, shows the result of NASA's DART spacecraft crashing into the asteroid moonlet Dimorphos. The Italian Space Agency's LICIACube was the only observer of DART's impact, besides the spacecraft itself.Image: ASI/NASA
Hubble view of Dimorphos impact debris
Hubble view of Dimorphos impact debris The Hubble Space Telescope captured this view of Dimorphos 285 hours after the asteroid was impacted by the DART spacecraft.Image: NASA/ESA/STScI/Hubble
NEO Surveyor
NEO Surveyor This artist's concept shows NASA's proposed NEO Surveyor spacecraft, a mission to discover and characterize most of the potentially hazardous asteroids that are near the Earth.Image: NASA/JPL-Caltech

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Mat Kaplan: DART smacked that asteroid. Now what? We'll find out this week on Planetary Radio. Welcome. I'm Mat Kaplan of The Planetary Society with more of the human adventure across our solar system and beyond. DART, the double asteroid redirection test was a brilliant success. No one is happier about this than Lindley Johnson and Kelly Fast of NASA's Planetary Defense Coordination Office. But Lindley and Kelly will tell us that we're not yet where we need to be to avoid a catastrophic impact on our world. My conversation with them is minutes away. We're even closer to checking in with Sarah Al-Ahmed. The next host of this show will drop by to share an article by our colleague Jason Davis about the water on Mars. Want to work for The Planetary Society? Sarah will also tell you about a couple of job searches underway. Bruce Betts will tell us when and where to enjoy the total lunar eclipse that is days away as this episode becomes available. The interstellar dust does not spell out Surrender Dorothy, but the green cloud otherwise looks like it could be the work of a wicked witch, and that's why it tops the Halloween edition of our free weekly newsletter, the Downlink. Down below is the Hubble Space Telescopes image of asteroid Dimorphos with dual trailing tails. You'll hear it mentioned in my conversation with Lindley Johnson and Kelly Fast. Think it's hot outside, probably not as hot as an exoplanet dubbed GJ 1252 B. How hot? Gold and silver would melt into pools on its surface. That's based on data from the Spitzer Space Telescope. As always, there's much more in store at Sarah Al-Ahmed has another couple of months as our digital community manager. Sarah, welcome back. Of course, it's our intent that you be heard regularly on these programs leading up to when you take over with the first Planetary Radio episode of 2023. You must be excited looking forward to that?

Sarah Al-Ahmed: Oh, I am. And it's so exciting to begin my training on this job. Already, I've had such a great time.

Mat Kaplan: I hope that continues. I hope you're able to say that you enjoyed this transition period once you reached January 4th. In the meantime, we've got other stuff to talk about, starting with an article by our terrific colleague Jason Davis. What a great writer. On October 25, he posted this piece called Your Guide to Water on Mars, which is as good a brief guide to where we're going to find H2O on the red planet as anything that I have read.

Sarah Al-Ahmed: People want to hope that there used to be life on Mars in the past. We know that this planet used to have oceans of liquid water, but something changed at some point. So getting an overview of what was the situation in the past, what is it like now and how we can use that water going forward with our science exploration is very useful, but it's just not the planet it used to be, and that's a little sad for me. How do you feel about that, Mat? That Mars used to be a place covered in water and now it's just a dusty rock?

Mat Kaplan: I love those animations that simulate what Mars may have looked like billions and billions of years ago. They're generally done with careful scientific accuracy so they don't show stuff growing all over the place. They just show all that water. Maybe someday we'll terraform it. But in the meantime, as Jason has written about, there's still quite a bit of water hiding away up.

Sarah Al-Ahmed: There is. And it's really useful to know how we can get at that for a few reasons. We want to find life or maybe where life used to exist on Mars, so water as we know it for life is useful, but we can also use that water for things like creating fuel or if we're going to send humans there, create human habitats, we might want that water for them to drink to create plants, or maybe if we're going to get really fancy with it, we can use that water and some Martian dirt to 3D print some habitats or something. That would be really exciting. Most of the water on Mars is locked up in water ice caps at the poles. Trying to get at that water at the poles is a little difficult because it's easier for us to send space missions to Mars somewhere near the equator. We need that cushion of atmosphere to really kind of slow down our space craft when they're incoming, so we try to head around that area. Finding water in other places outside of those poles is also very useful. Rovers on the surface have been looking at hydrated minerals that were formed on Mars in water, and if we can crunch those up, we can get to water there as well. But an easier way to actually get at the water on Mars is probably in ice under the surface. The surface is covered in this dusty layer, but when the Phoenix Lander was on Mars back in 2008, it actually just a little bit under the surface found water ice sitting there waiting to be harvested and after it was uncovered, of course that water sublimed, it disappeared over time. But knowing that there is water right under the surface in a frozen form could be very useful to us.

Mat Kaplan: I am looking at those wonderful images. I remember when they were grabbed. It wasn't that long ago by Phoenix. Just a few inches or centimeters underneath the surface and there is this white stuff, which sure enough is water. Very exciting stuff. Jason also, he goes into even more of how we might harvest this water at some point. Seems like a lot of trouble though to start crunching hydrated minerals when you may just have to dig down a little bit. Hey, I got an idea. We could build canals.

Sarah Al-Ahmed: Right back to the canal of old days.

Mat Kaplan: Yeah.

Sarah Al-Ahmed: Yeah. Build canals, harvest out all the water in there, create our own little water ecosystem on Mars. It'd be wonderful. Some spacecraft have been looking at different water deposits both in icy form and potentially in lake form. Don't get too uber excited about this, but we do have some evidence. Mars Express back in 2018 flew over the southern cap, the polar ice cap and found evidence that there might be an actual liquid water lake under that ice cap. And of course we've done more observations since then going back over it and some people have suggested that maybe it's not liquid water, maybe it's frozen carbon dioxide with some minerals mixed in there. But even just that suggestion is really exciting and looking at those locations from above, the topography over those supposed lakes looks very similar to the stuff over frozen underground lakes we see here on Earth. So that's really exciting too. But until we do more science, until we go back and try our hand at harvesting this water, who knows how it's going to go.

Mat Kaplan: Which of course all of us at The Planetary Society hope that this exploration of the red planet continues a pace. There is one other thing I know you want to mention before we let you go, Sarah, and that is a couple of opportunities that we have at The Planetary Society, both of them related to what you've been doing and what you will be doing.

Sarah Al-Ahmed: Oh yeah. I've been at the digital community manager at The Planetary Society for two years, which means I've been managing our social media audiences and in the background working on this digital community app project. But now that I'm moving on to Planetary Radio, we need someone to step into my old role. So something that we're trying to fill right now is a six month temporary position for our new digital community manager. So if you feel like you want to interact with our planetary society audiences and really get involved in our social media and maybe this app, that would be the job that you want to apply for. Another thing that's really going to help us out as we make this transition is we're looking for a freelance audio editor to come in and help me put the show together, but this person will also help us put together our monthly space policy edition with our chief advocate and senior space policy advisor, Casey Dreier. We're really hoping that we can bring someone on quickly, so if either of these jobs are exciting for you, please go to our website. You can find these job postings at

Mat Kaplan: It's a great organization. I can tell you from many years of personal experience, it's a great, great place to work with. Terrific colleagues like the one we've been talking to. Sarah, I look forward to continuing these conversations and then listening to you as you host Planetary Radio and participating in that digital community which will be premiering sometime early next year. Thanks very much.

Sarah Al-Ahmed: Thanks so much, Mat.

Mat Kaplan: Remember that you can leave a message welcoming Sarah and or saying goodbye to me using our new toll-free number 844-PlanRad. Thank you once again to all of you who have already emailed me so many wonderful messages at [email protected]. A quick break now and then an uninterrupted conversation with Lindley Johnson and Kelly Fast about saving the world.

George Takei: Hello, I'm George Takei and as you know, I'm very proud of my association with Star Trek. Star Trek was a show that looked to the future with optimism boldly going where no one had gone before. I want you to know about a very special organization called The Planetary Society. They are working to make the future that Star Trek represents a reality when you become a member of The Planetary Society, you join their mission to increase discoveries in our solar system, to elevate the search for life outside our planet and decrease the risk of Earth being hit by an asteroid. Co-founded by Carl Sagan and led today by CEO Bill Nye. The Planetary Society exists for those who believe in space exploration to take action together, so join The Planetary Society and boldly go together to build our future.

Mat Kaplan: Lindley Johnson and Kelly Fast have been my guests many times. Lindley is NASA's planetary defense officer and the lead program executive for the Planetary Defense Coordination Office created by the agency nearly seven years ago. His colleague Kelly manages the Near-Earth Object Observations Program that is also part of the PDCO. The success of DART led me to inviting them back for a discussion that puts this test in the much broader context of an international effort to save our planet from the space rock that will someday threaten to do to us what one did to the dinosaurs 66 million years ago, Lindley and Kelly, welcome back to Planetary Radio. We've been following the DART mission very closely. I was able to congratulate Nancy Chabot, the coordination lead for the mission and the entire team just hours after the impact, and we ran a lot of that live coverage on the show that just came a couple of days later. But this is my first opportunity to congratulate the two of you and the Planetary Defense Coordination Office because you have received great credit, your office, from that team, from all of the people that we have been talking to about planetary defense. So thank you for this leadership, which who knows, may someday just save the world.

Lindley Johnson: Thanks a lot Mat. And as I always like to say, planetary defense is a team sport. It takes expertise, guidance, and contributions from a wide range of folks. For the DART mission, as you're aware that's not only a US team, but an international team that has worked on that project and continues to finish it up now with the international observations that are going on.

Mat Kaplan: And I'm going to come back to that international angle across all of planetary defense. How about those images, and I'm not just talking about the DART images before impact, but all the other beautiful ones, including speaking of international, Lindley, LICIACube.

Kelly Fast: Well, all of them... The whole experience was amazing. I must say that even as we were watching the DART images come in, the views of Didymos and Dimorphos before the impact, we couldn't help but sit there analyzing what we were seeing, comparing to what we knew prior to that, getting to see those details. I mean, there was the planetary defense aspect, but certainly just the fact to be able to get to know some other small bodies in the solar system looking at Dimorphos, the rubble on the surface, wondering what type of impact there might be. Would there be a plume? And looking at that, it was like, oh my goodness, there's going to be a plume. And then as you said, those images afterwards from LICIACube, from the ground based telescopes, like from the Atlas Telescope that we fund, just those beautiful plume images, incredible data for planetary defense, but just so exciting just from a science and a public perspective to get to experience this.

Mat Kaplan: We have that Hubble captured image with those double tails. My gosh, did we create a comment? That's really going too far, isn't it?

Kelly Fast: I was an attendee for the Division for Planetary Sciences meeting remotely, and I remember one presenter mentioning active asteroids and then saying, "By the way, we just created another active asteroid."

Mat Kaplan: Lindley, during the live coverage, I don't know if you know it, but I saw you in the background in some of the shots there at APL, at Johns Hopkins University Applied Physics Lab. Not surprising to see you there.

Lindley Johnson: Well, that's where I like to be in the background.

Mat Kaplan: Kelly, where were you on that amazing day?

Kelly Fast: Oh boy. I had a small part in the impact broadcast answering a few questions and then when that was done, I rushed over to the guest event and watched with everybody else on some of the screens that were there at APL and so I was just enjoying with them. But then Lindley was there in the Mission Operations Center watching firsthand.

Mat Kaplan: I wish I had been there along with our boss, the science guy. It looked like quite a party for planetary defense.

Lindley Johnson: Yeah, I saw Bill there. He was having a good time.

Mat Kaplan: Oh yeah, he knows how to have fun. In my newsletter, I said that we now know that we have the ability to avoid the fate of the dinosaurs. Lindley, is that a premature statement or are we now close to that?

Lindley Johnson: Well, maybe a bit premature, but we have successfully demonstrated that a technique like a kinetic impactor can have an effect on the velocity of an asteroid, change its speed and therefore will be able to change its orbit. I think there's some yet to understand about everything we'd like to about that interaction. We were pretty confident that this was going to happen, but until you actually do something like this, you never know how exactly it's going to turn out. And I think there are a few things in addition that we will learn about this with closer examination of the data that the investigation team is getting now. Anxiously await their report out of how successful they think they were and what things maybe they didn't expect.

Mat Kaplan: I was actually surprised by how quickly we were told after the fact that sure enough, DART had done what we had hoped, not just impacting but deflecting the course of this little moon lit asteroid. Was that something that you folks expected to hear so soon and that it would be such a dramatic change?

Kelly Fast: Well, I know that the team had calculated kind of a wide range of period changes that would be possible all based on physics. So it was all reasonable, but it ended up being towards the higher end, which was great, and so that allowed them with confidence to come forward earlier to brief NASA headquarters so that every everybody felt comfortable with this to go ahead and come out with these results based on the light curve data and also based on radar, having different techniques confirming each other. So it wasn't outside of the realm of possibility, but it was nice to be able to come out and say something even sooner than conservatively planned.

Lindley Johnson: Yeah. Part of the reason for that is that the after impact observations were better, more successful in being able to collect the data than we thought they might be after the impact. So we thought it might be a week or so before there was enough clearing of the ejecta and such that reliable optical observations could be taken. But that turned out not to be true. Some of the southern hemisphere observatories were able to get pretty clean light curve data in that first week. Then the other major contribution there was the radar, Goldstone Radar. We didn't actually know how successful that was going to be. First of all, whether the radar would even be available that quickly for various reasons. Maintenance being one of them, that 70 meter dish is getting pretty old. Also, it's scheduling because that radio antenna gets used for all of our interplanetary communications. So scheduling that asset is a real challenge sometimes. It turned out to be available to get good clean data, not only just to be able to detect the two objects but also have enough signaled noise that they could actually do some imaging. That data coming in pretty quickly within a few days also led to the confidence that we could announce a lot earlier than we had anticipated.

Mat Kaplan: I didn't think of this until now, but had it still been available to us, would the late lamented Arecibo radio telescope, that most powerful radar instrument, would it also probably have been put to use?

Lindley Johnson: Oh, certainly. Some of the better radar imaging work was actually done bistatically as we would've probably used Arecibo, but in this case, the Green Bank 100 meter was used.

Mat Kaplan: When you say bistatically, do you mean that there were two radio telescopes involved?

Lindley Johnson: Yeah, Goldstone transmits and Green Bank receives.

Mat Kaplan: Oh, I see. Very interesting.

Lindley Johnson: That's how the bistatic works. I'd go into the great detail about how that all works. Don't want to absorb too much of your program here.

Mat Kaplan: Yeah, it'd be lost on me anyway, I think. But that is fascinating. I didn't know that that takes place. Doesn't this also the fact that we had this data back from largely ground-based facilities so quickly, doesn't this also say something about how much more sophisticated we have become in observing objects like this?

Kelly Fast: Well, yes. We are. I mean, as you know, there's such a large population of small bodies out there and that's why we have a planetary defense at NASA and trying to track them to know if any pose an impact threat and also fantastic science targets. But as we learn each time, we keep learning there's more to learn and they're all individual. They're part of populations and families, but they have their personalities and so having these close up observations are really helpful for better understanding our remote observations like light curves, like radar, like spectroscopy, all the things that we can do from the ground because we can't send spacecraft to all of them, but to be able to have spacecraft at some to understand their properties and to tie that into what we're able to do from the ground and to better understand the ground based data that will really help us to better characterize the larger population of asteroids out there, which is especially important for planetary defense and understanding what could potentially happen in the event of an impact.

Mat Kaplan: You also remind me of all that stuff that's coming back from Bennu very soon now and all those scientists who can't wait to get their hands on that material collected by OSIRIS-REx. Lindley, speaking of needing more data, we have this one data point now from an impact, unless you go back to deep impact a lot of years ago, which really wasn't sent to do this. It's a great data point, but I mean wouldn't it be great to have data from maybe five or 10 more DART type missions impacting different kinds of asteroids to really teach us what we need to know?

Lindley Johnson: Well, sure if you had unlimited resources or any number of things that you'd like to do. Yeah, this is one data point so to speak, but I think it's a pretty rich data point and I think there will be kinetic impact tests done in the future. I think there are a few other priorities that we have in planetary defense first though, and of course the first one is we need to improve our capabilities for finding these objects and knowing where they are and where they're going. So the next highest priority of planetary defense mission is the NEO Surveyor. Getting that capability on its way to the launchpad and into operations so that we have time to find these things well ahead of time. Every year that a capability like that slips is a one less year that we might have if there were an asteroid on its way to Earth. So that is our highest priority thing. Also, as Kelly was saying, our ability to observe these things and learn about their character from the ground is improving more and more every time we do these kinds of things. It's very much an interdict process, but there's still nothing as good as actually getting a spacecraft out there to look at it and do a more up close examination so that we know what we're dealing with. So, as the planetary science decadal says another priority is a rapid reconnaissance capability. If we do find an asteroid on its way to Earth, we don't have a lot of time, we're still talking several years but perhaps not decades. Being able to get out there fairly quickly to get a look at it prior to deciding what is going to be the best technique that could be used against it to change its trajectory. And so that also gets into some other things that we want to try to do and that is kinetic impactor may be one tool that we will not have in our toolbox if we're ever faced with such a threat. We'd like to have two or three tools because in our studies of this, it all really depends on the scenario, what might be the best way to interact with the asteroid and change its orbit. So testing some other techniques I think would be higher on our agenda than doing another kinetic impact test. I think we will eventually get back to that as we sustain our planetary defense efforts, but we should test some other techniques like a gravity tractor or an Ion Beam Deflection. There's some other ideas out there as well that we should take a look at.

Mat Kaplan: Our boss, the science guy, once again, he still likes to talk about those laser bees that The Planetary Society helped develop at the very early developmental stage, a swarm of spacecraft out there shooting not ions but photons to asteroids to divert them. Just last week on the show I had Melissa Brucker, principal investigator for Spacewatch, Eric Christensen, same job for the Catalina Sky Survey. They both told me how much they are looking forward to the launch of that spacecraft you just mentioned NEO Surveyor, the mission led by their University of Arizona colleague, a friend of this show, Amy Mainzer. As you know, Planetary Society is big proponent of this project and so excited to see it moving forward. Unfortunately I didn't get to visit Amy while I was at the University of Arizona. Timing was wrong. She was a JPL for a major mission development review, so I didn't get to see the camera that's coming out of her lab. At the risk of boring some listeners who've heard this many times before, would the two of you talk about why it's so important we get this infrared telescope out there in space?

Kelly Fast: Well, I'll lead off and kick to Lindley. As you said, you spoke to Melissa and Eric and about the efforts to find and follow up asteroid discoveries and our ground based efforts. They're doing a fantastic job and they're racking up discoveries every year and they're doing their best to really optimize how they're doing it to be most effective and to do it as quickly as possible, but they still have limitations and have to wait for the asteroids to kind of come close enough to be discovered. So really everybody, the community over the years keeps looking at how do we speed this up? And the planetary decadal and previous decadal or rather academy studies and other reports kept pointing to the need for a space based infrared telescope. And so to actually see this coming together is really encouraging because that would be the way to really accelerate efforts to find near-earth asteroids to better understand their sizes and to maybe see the populations that are harder to see from the ground. And so to have NEO Surveyor in concert with the ground based telescopes, that's going to be really powerful and as Lindley noted earlier, the longer we wait, the more of a chance there might be something out there that we're going to lose the lead time on. And so it's so important to keep moving forward with this.

Lindley Johnson: There is no quicker way to get a full handle on the population of hazardous objects that are out there. Then as space based IR telescope specifically designed to do this job, there have been several studies over the last decade that confirm that also the most recent planetary decadal survey reinforces that point as well. NEO Surveyor is designed from the ground up to do this job and do it relatively quickly even though it was still take about 10 years for all of the objects that could represent a hazard to the earth to come within a viewing range because these orbits wonder all over the solar system so to speak, their orbital paths are defined but they are all over the solar system, at least between here and Jupiter. So it takes a number of years for them to come in close enough into earths vicinity for us to pick them all up.

Mat Kaplan: Do we still think that there are about 25,000 of the biggest of these space rocks, the ones that NASA was directed to find 140 meters or what is that 460 feet or so in size, the ones that could really ruin the day of pretty much everybody on earth?

Lindley Johnson: That is our current estimate of the population. Now we study that every few years and in fact we have a study going on right now to update that estimate. In the next year we'll probably have results of that study, announce the results of that study and we'll see what the latest data shows us is that remaining population.

Mat Kaplan: I am sure we will be covering that when it happens on Planetary Radio and even though you may be talking to somebody else by that time. How would you characterize our success at this effort? I mean really one of the most rewarding things for me to have watched over the 20 years or so that I've been doing this show is the growth of both public and institutional awareness of near-earth objects, the threat that they present and the advances they make, really the advances we have made in detecting them, in tracking them, in characterizing them, and now in deflecting them as well. But it really seemed to kick into high gear with the creation of the Planetary Defense Coordination Office and I note that that was only going on seven years ago. I guess, PDCO was coming up on an anniversary?

Lindley Johnson: Yeah, we're going have our seventh anniversary here in January. Not that a lot of work didn't proceed that. Any mission of this sort, well, it takes a lot of things, but it takes at least two things and that is having the assets that have the capability to do the job and it takes the will to do the job. It takes people that understand the problem and be willing to step up and do something about it. It took us a while to first of all understand that there still is a hazard there and to collect enough information data about it to understand the level of the potential hazard, and that was all well and good for the astronomers and the scientists to maybe understand that. But it takes more than that to have a viable space program. Communicating that information in an understandable way to those that need to make those kinds of decisions takes some time as well. And sometimes you have to craft a message two or three different ways before it penetrates through all the other things, all the other priorities that you're competing with in a way. But working at NASA for 20 years and I worked in the Air Force for 10 years before that and that seems like a long time, but iteratively more and more every year, more and more people began to understand what we're dealing with there and more and more support behind it. NASA getting curious about it mid part of the last decade and that led to the establishment of the Planetary Defense Coordination Office and more understanding and then support to our budget is what has allowed us to get to the point we are. Not that we don't have a little further to go. So we continue to beat that drum and get us where we need to be with launch of NEO Surveyor and a planetary defense program that is at a sustainable level out into the future because this is a legacy project, this is something that we earthlings and guiding our spaceship earth through this solar system need to pay attention to is the debris that might lie in our way.

Mat Kaplan: It's a dangerous place that we live and we are preparing to deal with those dangers at least. And I'm very proud that my organization, Planetary Society, I think we've played a little bit of a role in helping people be aware. But Kelly, I think it also with apologies to the thousands of people who suffered in a real way from it, it probably doesn't hurt this effort to have it something like Chelyabinsk every 10 or 20 years.

Kelly Fast: Well yeah, sadly that was sort of a wake up call that impacts still happen in the solar system. The Shoemaker-Levy 9 impacts with Jupiter in 1994 was a wake up call, and Chelyabinsk unfortunately was a wake up call that was far too close to home but it helped remind people and maybe it was one of those events that helped to push efforts along but as Lindley kind of quietly noted that he's been working this for the past 20 years and even 10 years before that when he was at the Air Force and I've only been in this the past decade, but it's kind of those quiet and persistent efforts of over decades to try to keep running the ball down the field and working with the rest of the community that's been working this so hard. And then also, like you said, the communication. I mean, Mat, you're 20 years with doing this with Planetary Radio and circling back to this topic over the years. That and just all the other events happening at NASA really helped I think to get the message out there to the point where most recently with the DART impact, a lot of the reporting was very well informed and not as sensational as maybe it has been in earlier years. The message is getting out there in a realistic way. We just went through a pandemic. There's other situations that are higher likelihood that we have to deal with, but this is still something we don't want to forget about. As Chelyabinsk showed it can happen that we can have an asteroid impact. We might not have anything like that again in our lifetimes, but we need to know and if we have the capability we've got the technological know-how, then it's time to get to that point and that's what Lindley and others in the community have been working so hard for so many years.

Lindley Johnson: We now have the knowledge and the technology to prevent this from ever being a major natural disaster. I think it is prudent to take those steps to make sure that asteroid impact isn't one of the natural disaster we need to fall victims to.

Mat Kaplan: Kelly, I want to come back to you for a moment because I didn't let you respond when I talked about the advances that we have made and how much better prepared we are now to find these objects and do all the other stuff we need to learn about them. And I mentioned Spacewatch, Catalina Sky Survey, both of those principal investigators gave lots of credit to the PDCO and NASA for making it possible to do the work that they do. I mean, there are so many resources that NASA is in support of, the Sky Surveys and so much of the other stuff that we've already talked about on the show. Is there anything else that you want to call out? I mean I think of the Minor Planet Center or CNEOS, that center run not far from The Planetary Society at JPL.

Kelly Fast: Right. The Near-Earth Observations Program, it handles the funding of all the non flight activities in the Planetary Defense Coordination Office, which are the surveys, the telescopes looking every night to find the asteroids and all the follow ups like when you've spoke to Catalina and to Spacewatch. As you said, there are other activities that are really, really important because it doesn't help to observe an asteroid if you don't know something about where it's going to be in the future. And so the program does fund the Minor Planet Center, which is the International Astronomical Union recognized repository for small body position measurements from all over the world of all small bodies, not just near-earth asteroids. But that's funded by the program and then the Center for Near-Earth Object Studies. They take those data that are submitted to the Minor Planet Center and they look at the orbits of these objects way out into the future to try to determine if any pose and impact threat into really do that precision orbit determination. We had a kind of little exercise case earlier this year when an asteroid that ended up being designated 2022 EB5 ended up being discovered in space and then impacting Earth and their prediction was spot on. And so it was a nice little exercise with an asteroid that only would've made a pretty fireball, but helps us to know we're ready for the future. We have the Asteroid Threat Assessment Project out at NASA Ames, which does the impact modeling of what happens to an asteroid as it passes through earths atmosphere and what would the impact effects be with what survives to the ground. And all of that is very valuable for this large interagency exercise that was held earlier this year with other US agencies looking at the roles in the National Near-Earth Objects Strategy and Action Plan. Plus we also have efforts that characterize asteroids, that do spectroscopy to look at their physical properties, which feeds into what the impact effects might be of an object. So all of those things really tie in closely together to give that all of the data needed should we ever find ourselves in an impact threat situation to be able to pull all of that together. And so a lot of really important research just going on day to day through the program and coordinating strongly with our interagency and international collaborators around the world. The International Asteroid Warning Network, as Lindley said, this is planetary defense. It's a team sport and so it's really important to grow the activities at NASA to the appropriate level so that we do what Congress tasked us with and what the decadal is pointing to, but also to collaborate and to assist with activities around the world since it is such an important team sport.

Lindley Johnson: It's not an accident that the word coordination is in our office name, Planetary Defense Coordination Office. There's a lot of work to coordinate all the efforts that go into this. You could think of the PDCO as being the coach for planetary defense.

Mat Kaplan: Planetary Defense Coaching Office. I want to circle back, Lindley, because I said I would to that international participation. Have you seen growth in concern and interest in planetary defense initiatives growing around the world in parallel with what we have seen in the United States?

Lindley Johnson: Well, certainly, and actually Kelly can give you some firsthand knowledge about this, but from when we started more organized international efforts back in about 2007 because it had been identified on the program for the United Nations Committee on Peaceful Uses of Outer Space as an activity that needed to be at least studied by the international space community if not agreements made on what should be done. That effort started back in 2007 as part of a action team that the committee had set up. There was maybe be a handful of representatives from space agencies like NASA and ESA, European Space Agency that were involved in those original studies and such. We pulled some of the other major agencies in the course of four or five years, which then led in 2013 sort of as the emphasis put on it by Chelyabinsk, a recommendation as to what the international community should be doing at the very same time that Chelyabinsk happened. I was actually in Vienna at the committee meeting, subcommittee meeting actually preparing to present our recommendations for the establishment of the International Asteroid Warning Network. Chelyabinsk happened the morning, the day before we were to do that.

Mat Kaplan: Talk about cosmic timing.

Lindley Johnson: Yeah, well that's the second time in my planetary defense career that cosmic timing came into play that really put an emphasis, exclamation point, if you will, on our recommendation for establishing these two international entities. They are not UN, United Nations entities. They are international collaborative efforts, a coalition of the willing, if you will. And all they started off of fairly small with only a few members. That membership has grown now. We just had meetings of these two entities last week. We are now 18 space agencies and space offices. National space offices are full fledged members of that organization and we have a couple of more that are looking at joining as well. They've been observers in the last couple of meetings and we fully expect them to submit their petitions for being admitted to membership here in the next meeting or two. Kelly can tell you about the IAWN's growth as well.

Kelly Fast: Yeah, the International Asteroid Warning Network has now grown to 40 signatories from 20 countries. There's a lot more participation now from everyone ranging from space agencies and institutes and universities down to very capable, independent and amateur astronomers all contributing to the observation effort, whether survey or follow up or characterization or orbit determination. And so it's come a long way from that meeting in 2013 that Lindley mentioned with that Chelyabinsk exclamation point.

Lindley Johnson: And those are just the official members.

Kelly Fast: Yeah, that's right. That's right. The IWAN has worldwide observing campaigns to kind of exercise the worldwide system on the observing side or to improve, check the status of our capabilities and prove them. And you don't have to be a member of IWAN to participate. And so that's been really important too. And so as more participate, we're encouraging them to actually join IWNA and there's more at on that, but we're very proud of how far things have come and how much fantastic work the participants have been doing, especially on the campaign front.

Mat Kaplan: We will put up a link among many others that are relevant to this conversation to that IWAN, site that you can explore on this week's show page at I'm glad you mentioned the work of amateurs. Kelly, as you know, I can't help mention it. Of course, our Shoemaker NEO program that we do out of The Planetary Society assisting mostly amateur astronomers to improve their abilities to help find and now more often track and characterize these objects. So it's a game that apparently almost everybody can participate in.

Kelly Fast: Right. In those cases. I know that there's some of those very capable amateurs that have benefited from the Shoemaker grants. I know that some of them are members of IWAN and so that's really fantastic too. So that contribution, the ripples continue there.

Mat Kaplan: Last year I very much enjoyed having the writer, director, producer, Adam McKay on our show. He of course made that what I think was a terrific movie, Don't Look Up, he was joined by Amy Mainzer, who the two of well. We've already mentioned she was the science advisor to that production and I just want to congratulate you on being played so well by the actor Rob Morgan in that movie.

Lindley Johnson: Yeah, I thought he did a fantastic job as well and he was one of the few characters that came off looking pretty good in the whole fiasco of that movie. So I was happy about that.

Mat Kaplan: I don't think that there has been in the history of this planetary defense effort, anything quite as visible in the popular media as that movie. Even though that movie, the director will tell you, was not really about planetary defense, but they did a pretty good job, didn't they?

Lindley Johnson: Yeah. Well, they did a pretty good job of spoofing just about everybody. Well, that's the most recent example certainly. But cosmic impact, asteroid comet impact, it's been a genre of science fiction since it's very start almost. And so there have been a number of movies over the years. Maybe not everybody remembers Armageddon and Deep Impact, but certainly our generation does.

Mat Kaplan: They should remember Deep Impact. Maybe not Armageddon.

Lindley Johnson: Armageddon had a great soundtrack. I like the soundtrack anyway. But I like the movies all the way back to the movie Meteor back in the late 60s.

Kelly Fast: Which I'll say... I'll throw this in there because Lindley won't. In the movie Meteor, Sean Connery played him.

Lindley Johnson: And that's even before Planetary Defense Office existed.

Mat Kaplan: I'll go back even further When Worlds Collide, which I actually read the book before I saw the movie. You're right, I guess. This is a genre in filmmaking. Well, let's hope that it stays in the area of filmmaking, the disasters that these often depict. And we can thank the two of you, the PDCO and this worldwide effort if we are able to avoid that fate that is depicted in so many of those movies. Just one of the question for you, the next Planetary Defense conference is coming up in spring of 2023 in Vienna. Will I see either or both of you there?

Lindley Johnson: Well, hopefully if all the asteroids align, you'll see both of us there.

Mat Kaplan: Thank you both very much. It has been a great pleasure to talk to you yet again on Planetary Radio. Thanks for all the great work that you're doing. Keep looking up.

Lindley Johnson: Absolutely.

Kelly Fast: Thank you Mat.

Mat Kaplan: It's time for What's Up on Planetary Radio and we have the chief scientist of The Planetary Society to walk us through it. Welcome Bruce Betts.

Bruce Betts: Thank you. Thank you very, very much. Thank You.

Mat Kaplan: From Laura Dodd in California. You're awesome too, Bruce, please don't announce your retirement just so you could get some of the love lavished on Mat.

Bruce Betts: Aww. Thanks to you Laura. I won't. I'll be here. I'll be here with Sarah pining for whatever that guy's name was, who used to be the host.

Mat Kaplan: How soon they forget. And I'm not retiring. How many times do I have to say it? I am leaving behind being host. Go on to What's Up.

Bruce Betts: Okay, so in the sky we got a bunch of stuff. Jupiter and Saturn in the south and the early evening are south east. The moon is hanging out between them from the 2nd to the 4th of November. On the 4th it's hanging out near Jupiter. We've got reddish Mars rising in the mid evening and it's very bright. Very bright, spectacular. Will continue to brighten all month as Earth and Mars grow closer in their orbits. Now we move on, not to another segment, but to the cool total lunar eclipse that will be visible from the Americas, the Pacific Ocean and everything in it, Eastern Asia and Australia. Okay, maybe not everything in it. Things really deep won't see it. I can see Mat's preparing to school me on that. And that is the night of November. November 7th through the 8th. So for most people the date will be November 8th, but it's the night that starts on the 7th. Partial eclipse when it gets easy to start being seen will be about nine o'clock UT, 9:00 UT which of course if you're there means you're bumming because it's daylight. But if you're say where we are, it'll be at 1:00 in the morning-ish for Pacific time. You can look up the times and find the maximum eclipse is about two hours later. The eclipse ends about three and a half hours of good eclipse. Although if you're on the eastern coast, say of the Americas, the moon will set during totality, but we get to see all of it.

Mat Kaplan: That's a very thorough explanation and so nobody has any excuse for missing this unless you live at the bottom of the ocean or past the [inaudible 00:49:46].

Bruce Betts: Giant squid will be challenged to see this, but those giant eyes may help out. We move onto this week in space history. 1973, the launch of Mariner 10, first mission to go hang out at two planets studying Venus and the first and only for a few decades to study Mercury up close.

Mat Kaplan: Till Messenger got there.

Bruce Betts: Onto random space facts. Ganymede is the largest moon in the solar system. But you knew that, but did you know that even though it's the largest moon in the solar system, more than 14 Ganymedes would fit inside the earth?

Mat Kaplan: No reason for us to feel inferior in this collection of worlds that we fly around in.

Bruce Betts: Yeah, we'll just ignore those big gassy things.

Mat Kaplan: Yeah.

Bruce Betts: We move onto the trivia contest where I asked you what video game popular in the 1980s owes its name to William Herschel? How'd we do, Mat?

Mat Kaplan: There was not a huge response. In fact, we only got maybe a third of the normal number of entries for this one. I was surprised. I thought that this would be a pretty popular one. Interestingly, and this is maybe a first, Dave Fairchild, our poet laureate doesn't always prepare a poem, but with this one, he didn't have the answer. He said, "I have nothing." Bruce has beaten the poet laureate.

Bruce Betts: Yes, it has been so long. I may now turn on my microphone. No, I'm just kidding. Don't worry, Laura. I'm staying around.

Mat Kaplan: Matthieu Atzenhoffer in California. Not the winner, I'm sorry, Matthieu. He said, "Why? It's my favorite game from the 1980s. There was one at the po-boy stand across the street from my family owned service station when I worked as a kid and now I'm homesick and hungry." What's he talking about, Bruce? What video game?

Bruce Betts: Asteroids.

Mat Kaplan: Yes.

Bruce Betts: Of course, you can still find even online. Now they can just shove it into a web browser. Yeah, because William Herschel, although I hear we have some debate on this that you'll tell me about. William Hirschel is usually given credit for coining the term asteroid to describe Ceres when they gave up on it being a planet.

Mat Kaplan: Yes, asteroid. Asteroids was the term that Bruce was looking for. And you're right. I mean, we heard for example, from Robert Johannesson in Norway. He says, "I learned that the term asteroid may not have been coined by Sir William, but rather Charles Bernie Junior, son of Charles Bernie Senior, of course, a friend and colleague of Herschel's." But wait, Claude Plymate said, "It has recently been stated by a noted British historian that it was Stephen Weston who coined the term asteroid and he was applying it to Ceres and Pallas." Oh my gosh. There's more. Esson Beglue in Ontario, Canada, Caroline Herschel's younger brother Frederick William coined the term asteroid for minor planets. He did so after observing and confirming the recently discovered bodies, Ceres. So everybody connected to Herschel, but I don't know, there's this conspiracy to take away credit from Sir William, I guess.

Bruce Betts: I did find out that William Herschel actually discovered centipedes, so he's also responsible for the video game Centipede.

Mat Kaplan: Nice try. I do have one poem for you from Gene Luen the state of Washington, "The golden age of arcade games, the 80s are so known, and fighting in a 2D space is how dart skills once were honed. They came at you from every angle, zap the big ones into rubble. But if you found yourself surrounded, hyperspace could get you out of trouble. Though this small move of desperation placed you at random in the void and could drop you directly in the path of a cathode-ray tube asteroid."

Bruce Betts: Wow.

Mat Kaplan: Here's the winner. I don't actually have a name. All I have is BP. That's what he or she entered with, BP in Oklahoma. Congratulations. The response had asteroids. I couldn't have said it better. Thank you BP. And you are going to be getting one, a Planetary Society kick asteroid, rubber asteroid of your very own that you can characterize and track. That's going to be the prize next time as well, Bruce, since we just finished talking to those two leaders of the Planetary Defense Coordination Office. Another rubber asteroid for the winner of the contest that Bruce is going to introduce right now.

Bruce Betts: What former JPL director or directors have won the US National Medal of Science, a very prestigious award. Go to

Mat Kaplan: Come on folks. This ought to be fairly easy to Google, or Bing, or DuckDuckGo. You have until the 9th. You have until November 9th, Wednesday at 8:00 AM Pacific time. November 9th, get the chance to win yourself one of those fabled rubber asteroids.

Bruce Betts: AltaVista.

Mat Kaplan: Yahoo.

Bruce Betts: Yahoo. All right, everybody go out there, look up the night sky and think about how we would say asteroid, if Scooby Doo had recommended the word. Thank you and goodnight.

Mat Kaplan: I'll bite. Lay it on us.

Bruce Betts: Asteroid.

Mat Kaplan: Thank you, Scooby. He's Bruce Betts and sometimes Scooby, the chief scientist of The Planetary Society, who joins us every week for What's Up.

Bruce Betts: I love you, Mathew.

Mat Kaplan: Down, boy. Join me again next week for a Sagan Day conversation with Ann Druyan. Planetary Radio is produced by The Planetary Society in Pasadena, California and is made possible by its members who are defenders of earth. You can become part of this important quest when you visit Mark Hilverda and Rae Paoletta, associate producers Josh Doyle, composed our theme, which is arranged and performed by Pieter Schlosser. Ad astra.