Planetary Radio • Aug 30, 2023

A new algorithm finds its first potentially hazardous asteroid

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On This Episode

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Mario Jurić

Professor of Astronomy and Senior Data Science Fellow at the University of Washington, Director of the DiRAC Institute

Aren heinze portrait

Ari Heinze

Research Scientist at the University of Washington

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Rae Paoletta

Director of Content & Engagement for The Planetary Society

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Bruce Betts

Chief Scientist / LightSail Program Manager for The Planetary Society

Sarah al ahmed headshot

Sarah Al-Ahmed

Planetary Radio Host and Producer for The Planetary Society

A next-generation asteroid discovery algorithm, HelioLinc3D, has successfully identified its first potentially hazardous asteroid. Mario Jurić and Ari Heinze from the University of Washington join Planetary Radio to discuss the upcoming Vera Rubin Observatory and how their team's new asteroid detection algorithm can help defend our world. The Planetary Society's director of content and engagement, Rae Paoletta, marks the successful landing of the Indian Space Research Organization's (ISRO's) Chandrayaan-3 mission on the Moon. Then Bruce Betts, the chief scientist of The Planetary Society, pops in for What's Up and a conversation about space dreams.

The orbit of 2022 SF289
The orbit of 2022 SF289 This rendering shows the orbit of asteroid 2022 SF289 (green) at its closest approach to Earth (orbit in blue). The orbits of Venus and Mars are shown in orange and red, respectively. Asteroid 2022 SF289 was detected by HelioLinc3D, an asteroid detection algorithm created for the upcoming Vera C. Rubin Observatory.Image: Joachim Moeyens / University of Washington / OpenSpace
ATLAS observations of 2022 SF289
ATLAS observations of 2022 SF289 These are the ATLAS survey observations used to detect asteroid 2022 SF289, visible in the red boxes.Image: ATLAS / University of Hawaii Institute for Astronomy / NASA


Sarah Al-Ahmed: A new asteroid hunting algorithm proves its worth this week on Planetary Radio. I'm Sarah Al-Ahmed of The Planetary Society. With more of the human adventure across our Solar System and beyond, a next generation asteroid discovery algorithm called HelioLinc3D has successfully identified its first potentially hazardous asteroid. Mario Jurić and Ari Heinze from the University of Washington join us this week to discuss the upcoming Vera Rubin Observatory and how their team's new asteroid discovery algorithm could help us defend our world. In a moment, The Planetary Society's editorial director, Rae Paoletta will join us to celebrate the successful landing of the Indian Space Research Organization's Chandrayaan-3 mission on the moon. Then Bruce Betts, the chief scientist of The Planetary Society, will pop in for what's up and a conversation about space dreams. It's the first week of a new month, which usually means that it's time for a new space policy edition of Planetary Radio, but I want to remind all of our loyal space wonks that our monthly space policy edition is on hiatus for September and October. And for the happiest of reasons, our chief of space policy, Casey Dreier, is on paternity leave. He and his family are busy welcoming a new tiny human to the planet Earth. Congrats to you and your family, Casey. But in the meantime, if you're a fan of space policy, Casey's recent episodes on the Artemis program, Mars Sample Return and the policy implications of active SETI are fantastic and totally worth listening to. You can listen to them on any of your favorite podcasting apps or find them on our website at But we have to start this episode off by sending a huge congratulations to ISRO, the Indian Space Research Organization. The Chandrayaan-3 mission successfully touched down in the moon's south polar region on August 23rd, 2023. It's a huge victory for their space agency, but also for all of humanity. Here's our editorial director, Rae Paoletta with the details. Hey Rae.

Rae Paoletta: Hey, how's it going? Happy to be back.

Sarah Al-Ahmed: And we have a lot to celebrate. This is a huge moment not just for ISRO, but I think for all of humanity.

Rae Paoletta: Yeah, what a moment indeed. I mean, India's officially the first nation to successfully land near the lunar South Pole.

Sarah Al-Ahmed: And the only reason we know that that's such an important place on the moon is because of India's previous missions there. This is so cool.

Rae Paoletta: Yeah, it's really incredible. It's cool to see that this is sort of the follow-up and that we're going to learn potentially so much more about this really permanently shadowed, interesting mysterious region of the moon.

Sarah Al-Ahmed: And this is a place that could potentially be really key to our future exploration of the moon if we're going to be sending humans there. Can you tell us a little bit about why the South Pole is such a great location?

Rae Paoletta: Absolutely. I mean, there's just so much scientific mystery that's just waiting to be unraveled over there. I mean, so just for context, for those who don't know, the lunar South Pole region has a ton of these cratered, permanently shadowed regions that scientists think might have water ice deposits. And so water ice is extremely interesting for a number of reasons, but one of them is that if you're thinking about potentially establishing lunar settlements or places for astronauts on the moon, it's going to be really helpful to have water there because water is super heavy and it can be really expensive to travel with. So having that on the moon would be really helpful for those teacher missions. There's also just so much we can learn about this region from a geological perspective, right? I mean, you can learn so much potentially about the history of geological activity on the moon, perhaps past volcanic activity. A lot of people don't know that the moon was volcanically active for potentially long stretches of time. So what can the South Pole teach us about this from a scientific perspective? There's just so many questions. I'm looking forward to finding out the answers together.

Sarah Al-Ahmed: And I feel like we got to double praise ISRO for this because it was their Chandrayaan-1 mission that detected this water at the South Pole with their moon mineralogy mapper. It completely changed everything about what's going to be in our future on the moon, and so all the props to their space agency. They've done a fantastic job.

Rae Paoletta: This is so cool because also from a historical perspective, India joins a very small group of countries now that have ever successfully landed a spacecraft with on the moon. So it's really just the US, China and the former Soviet Union. Those are the only other nations. So the fact that this is the fourth country to ever accomplish that particular feat is so cool, and my hat's off to ISRO and just India. I'm so, so excited and congratulations to everybody.

Sarah Al-Ahmed: They should be really proud of themselves because we all saw what happened with their last Chandrayaan-2 mission. They tried so hard to land on the moon and space is hard. We have to keep relearning this, but unfortunately Chandrayaan-2 crashed. So seeing the lessons that they learned from that applied to this new mission and seeing just the joy in that audience when they landed. I loved watching that live stream, it filled my heart with joy.

Rae Paoletta: Oh, yeah. Seeing the joy in the control room, it felt like you were right there and it was just so cool to watch. I'm just so happy for the whole team really.

Sarah Al-Ahmed: So what is Chandrayaan-3 going to be doing at the South Pole location?

Rae Paoletta: So the lander and the rover will... I think they've actually turned on several of their instruments already to do a whole host of exploration. For example, I know that obviously they'll be making measurements of the lunar soil. They'll also be taking a look at the ionosphere. A lot of people think the moon doesn't really have an atmosphere and it has a very tenuous atmosphere. So doing some further calculations and research into that, should be really interesting. Yeah, looking forward toward the next, I think it's 14 days that it'll be taking experiments, so it'd be cool to see what comes out of that.

Sarah Al-Ahmed: I don't know if this is just me, but I feel like there's something about this mission that makes me just a little emotional, and it's because you and I, we weren't alive when the first humans landed on the moon. And back then it was a space race between two nations trying to get there competitively, but now we're at this dawn of a new age of lunar exploration, not fighting each other but going together, and India just signed on to the Artemis Accords in June. So we're all on a team together and I think there's something really beautiful about that.

Rae Paoletta: Yes, I agree completely. Space belongs to everybody and I think that it's a team effort and it's just really cool to see this all come in together. And there does feel like a real sense of comradery with this.

Sarah Al-Ahmed: So if people want to learn more about Chandrayaan-3 or the other missions, where can they look for that on our website?

Rae Paoletta: Well, you can definitely take a look on our website on our Chandrayaan-3 missions page that's got all the latest up-to-date information there about this mission. You can also check out this really, really cool collaboration that our digital community manager, Ambre Trujillo did with Rashmi Sheoran, aka @astro_roxy, who's a space tutor at ISRO. Definitely check out one of her videos. She's a wonderful science communicator, so that's where you can find out more.

Sarah Al-Ahmed: And I'll link to all of these things on the page for this episode of Planetary Radio along with a link to the live stream because if you want a moment to make yourself happy about the future of space exploration, this is it and there's a lot worth celebrating. Congrats ISRO.

Rae Paoletta: Yes, congrats ISRO. Yay. Congrats India

Sarah Al-Ahmed: And thanks, Rae.

Rae Paoletta: Oh yeah, my pleasure. Any time.

Sarah Al-Ahmed: And now for our main topic of the day, using algorithms to save the world from asteroid impacts. When it comes to planetary defense, algorithms are often the unsung heroes. We use them to process data collected by asteroid hunters and surveys, but the existing algorithms have their limits. A next generation asteroid discovery algorithm called HelioLinc3D has just proven its prowess by identifying its first potentially hazardous asteroid called 2022 SF289. This algorithm is being developed in preparation for the Vera C. Rubin's 10-year sky survey. The observatory isn't online yet, but the teams that are working on it are preparing for the data that's to come by making new algorithms to process it. Now that they're testing their algorithm on actual data, they've managed to detect an object with fewer observations than currently existing algorithms required. That means we're going to have an easier time detecting and tracking near-earth asteroids, which could literally help us save the world. The Vera Rubin Observatory is being built in the beautiful Chilean Andes and it's such a commence operations and join the hunt for asteroids in early 2025. The new observatory uses a massive 8.4 meter mirror and it's attached to a 3,200 megapixel camera that will allow it to scan the sky at an unprecedented pace. It should dramatically increase the discovery rate for potentially hazardous asteroids, but crunching that amount of data poses some really interesting challenges. The telescope's observing cadence visits spots in the sky twice per night instead of the typical four times. That means that we need a new kind of discovery algorithm to see the asteroids in the data. HelioLinc3D is being developed by a team at the University of Washington's DiRAC Institute and the fact that it's already spotted an asteroid and data when other algorithms missed that asteroid bodes really well for the future of planetary defense. Joining us to talk about the new algorithm are Mario Jurić and Ari Heinze. Mario is a Rubin scientist, the director of the DiRAC Institute, and a professor of astronomy and senior data science fellow at the University of Washington. He's the leader of the team behind the software that Rubin will use to discover the asteroids. Ari Heinze also works at the University of Washington as a research scientist. He's also a Rubin scientist and the principal developer of HelioLinc3D. Hi Ari and Mario.

Mario Jurić: Hi, Sarah.

Ari Heinze: Hello.

Sarah Al-Ahmed: I wanted to say congratulations to your team for making this discovery because I'm sure it's really validating to have this kind of proof that your HelioLinc3D algorithm is actually effective.

Ari Heinze: Yes, it is. Thank you.

Mario Jurić: Thank you.

Sarah Al-Ahmed: This is really just the beginning. This discovery was made in preparation for the Vera Rubin Observatory coming online and joining the hunt for near-earth objects, which we really, really need. There's a lot of them out there that we don't know of yet. And Ari, would you mind telling us a little bit about this new observatory?

Ari Heinze: So the Vera Rubin Observatory will be the biggest survey telescope ever built. It's designed to survey the whole sky or the whole accessible sky from its location and do all kinds of interesting science from the Big Bang and the first galaxies to really near-earth stuff like the asteroids that we are looking for. And because it has this huge flexibility, the observing cadence is not quite what the dedicated asteroid surveys use, and so that's why we've needed to pursue different algorithms to discover near-earth asteroids with the Vera Rubin Observatory.

Sarah Al-Ahmed: When is this observatory actually going to be joining the hunt for asteroids? Because it hasn't seen first light yet, right?

Mario Jurić: No, it hasn't. So it's been in the process of being constructed in Chile since... Oh my God, now it's been a while. Since 2015, 2014, and it will start in about a year. So in a year we get to first light or to what we're calling first photon and then about a year after that, so in about two years from now, that's when it's going to really be on the sky 24/7 or during the night.

Sarah Al-Ahmed: And it's going to be doing a very long survey of the sky. It has some kind of 10-year survey coming up that you're planning?

Mario Jurić: 10 years, that's right. The idea with this observatory, as I already mentioned, the way I like to think about it is we're trying to download the sky and put it into a database, sort of what Google does with the internet where they crawl the entire internet and then organize that information and then make it available to you through a simple query interface. That's sort of what Rubin is trying to do for astronomy. We're trying to image the entire sky, do it repeatedly over 10 years, take all those data, automatically process it, understand what's what, put the results into a database, and then allow astronomers throughout the US, throughout the world to write queries to ask for particular things that they're interested in from that database without actually having to go to a telescope.

Sarah Al-Ahmed: Of course, the fact that this thing isn't online yet means that you couldn't actually use data from the telescope in order to shape this algorithm for the telescope. I'm sure that was kind of challenging.

Ari Heinze: Yes. It doesn't feel like you can be sure the thing will work unless you can actually try it on real data. So that's why we've pursued these other data sets and they were challenging in another way because they're from the existing asteroid surveys, which use a different cadence, taking four images per night rather than two.

Sarah Al-Ahmed: What kind of cadence is this new telescope going to be taking images compared to the previous surveys?

Ari Heinze: So it's really a big paradigm shift in that the previous surveys take four images per night of each patch of sky that they cover and maybe they would cover 200 patches of sky per night, something like that, 200 fields. And they take the four images of each field over a period of typically about an hour or less, and they aim to discover something with one night's data. So at the end of the night, they submit asteroid candidates to the Minor Planet Center. People all over the world follow them up and they say, oh, we have a new near-earth asteroid with such and such an orbit that was confirmed by some list of observatories that got additional images. But the Vera Rubin Observatory will take just two images per night and the specifications for HelioLinc3D or for the Rubin asteroid link in general are that anything that is detected twice per night on at least three different nights within a two-week period should be discovered. We're not aiming for single night discovery anymore. That's actually impossible with only two images per night, but we are tackling the more sophisticated mathematical problem of combining data from multiple nights to make the discoveries.

Mario Jurić: One way to think about this is if you take four images per night, you can only cover half of the sky you would be able to cover if you take two images per night. So the reason why we traditionally took four images is because we just didn't have the software and the algorithms to connect all these dots that we see in any given night and be certain that these are asteroids. So that's what's novel in the code that Ari is writing that now we can, in some sense, unleash the full power of our telescopes because we can go and observe twice as much of the sky every night and discover all the asteroids at the same time and enable all other kinds of astrophysics from exactly the same dataset.

Sarah Al-Ahmed: Does that mean that because you're going to be taking only two of these kind of large images per night, are they more sensitive to light? Are you going to be able to see objects that are fainter within them?

Mario Jurić: That's one way to think about it, yes, because we'll be able to spend more time. I think the biggest gain though is just the area that we'll be able to cover. So one of the other things that this telescope is going to do for example, is look for supernovae and look for strange and variable and very rare phenomena out there in the universe. And so instead of covering the entire visible sky every week, we can now do it twice a week. So if there's something very odd that goes off somewhere, we have almost a factor of to a larger chance of seeing it. That's really where the big gain is.

Sarah Al-Ahmed: That's going to be so useful. I honestly wish we had these giant telescopes all around the world studying the sky because can you imagine what we would find out there if we could detect things overnight and had full data on the whole sky at all times? It would be amazing.

Mario Jurić: Well, we'll find out in two years and then if it's as good as we think it will, who knows? Maybe we'll have a network of telescopes like this.

Sarah Al-Ahmed: What dataset did you end up using in order to test your algorithm since you couldn't use this beautiful observatory that's still kind of waiting to turn online?

Ari Heinze: I used a dataset from a project that I used to work on actually until I moved to Washington two years ago called the Asteroid Terrestrial-impact Last Alert System or ATLAS. It's a NASA funded survey that is operated from the University of Hawaii, and it's actually not too different from the scenario you just mentioned, only with very small telescopes. They have two telescopes in Hawaii, one on the Big Island and one on Maui, and they have a telescope in Chile not too far from where the Vera Rubin Observatory is being built, and another one in South Africa. And so between those four telescopes, they try to monitor the sky as close to continuously as possible, but with far less sensitivity to faint objects than the Vera Rubin Observatory will have. So that was the dataset that I used and I chose that one because it's run by my former bosses and so I could ask them to share their data and that was easier than getting my hands on some of the other data that's out there.

Sarah Al-Ahmed: But that's a good connection to have, and if there's already a data set just waiting there with all this information within it, it seems like a perfect strategy. So far we've found about 2,000 potentially hazardous asteroids through detection methods, using algorithms, looking at these data sets. But how many of these things do we think are actually lurking out there that we haven't found yet?

Ari Heinze: We've found maybe 40 or 50% of them. That's my understanding of the current estimates.

Mario Jurić: Yeah.

Ari Heinze: And NASA has this directive from the US Congress to find 90% of them or 95% by some date, which I don't remember, but which is actually not physically possible at this point. So we're doing the best we can. An encouraging thing is that because of all the good work that's been done by ATLAS and all the other asteroid surveys in the past, we found the vast majority of the big asteroids that could cause a global catastrophe. And we're working our way down now to the smaller ones that are very dangerous. They could destroy cities or even countries, but they're not really a global Armageddon style disaster. The ones that are that big have essentially all been found, and so now we're working our way down to these dangerous but only sort of regionally dangerous, potentially hazardous asteroids.

Sarah Al-Ahmed: That's actually really comforting to know.

Mario Jurić: While we're talking, I looked up the current numbers just because they change almost on a daily basis and we know of roughly 2,400 potentially hazardous objects, but we expect about 3000 more are out there and hiding and waiting to be found. And so with Rubin, we hope to find at least another 2,500.

Ari Heinze: An interesting detail there is that these smaller but still dangerous asteroids can only be seen when they are relatively close to the Earth. And I don't mean they're heading for impact with the Earth, but just in relatively close passes. And that's part of the importance of the 10-year survey that the Vera Rubin Observatory will perform. We have to watch for a while in order to find all these things. We have to watch until they've all gone by the Earth at least once.

Mario Jurić: Yeah, they have to come to us so we can see them, but not too close.

Sarah Al-Ahmed: Not too close, stay away you guys. But these kinds of algorithms and more sensitivity in our instruments for detecting them will help with that and hopefully we'll be able to catch all those smaller, still dangerous ones before anything hits. I believe we can do it, especially now that we have this kind of technology. And it's also part of why at The Planetary Society we've been advocating so hard for missions like NEO Surveyor and other telescopes we can throw into space to try to help us out with this because there are some challenges trying to detect these things from the ground.

Ari Heinze: NEO Surveyor will be a great compliment to the Vera Rubin Observatory. They're optimized in different ways and they'll discover different subsets of the remaining potentially hazardous asteroids.

Mario Jurić: Yeah, 100%. The combination of the two is going to be incredibly powerful with NEO Surveyor not just finding objects but telling us how bright they are in the infrared and Rubin both finding objects and telling us how bright they are indivisible. So combine those two missions and we both get a very complete catalog of asteroids and we know exactly their sizes. So those there are going to game changers.

Sarah Al-Ahmed: And the more data we have on their location and where they're moving, the more accurately we can predict whether or not they're actually going to hit Earth because you can't just get that from two images unfortunately. You can try.

Mario Jurić: Yes. I think on average, Rubin will observe a typical asteroid, it's something between 100 to 200 times over its 10 years. So we'll not just know that it's out there, we'll know very precisely where it's moving and where it's going to go.

Sarah Al-Ahmed: Can we get any kind of data on maybe what they're made of? Is there any kind of spectroscopy that's paired with us?

Mario Jurić: So Rubin will not do spectroscopy directly, but we will observe these objects in six different optical bands. That gives you a sense of their colors, of some of the properties of their surfaces. So from just that, it's already possible to tell whether this is an object that's made out of silicates, a stony asteroid or whether it's a metallic asteroids or something else. So we'll have pretty good taxonomy by the end.

Sarah Al-Ahmed: That's amazing. Ari, I wanted to ask you this because you're the principal developer of this algorithm and you've already kind of touched on this, but how do asteroid detection algorithms actually work?

Ari Heinze: So the older kind looks for anything that's moving in a straight line across the sky for one night, and we can't use something exactly like that for linking data across multiple nights because asteroids don't continue to move in a straight line because of the curvature of the Earth's orbit around the sun, the curvature of the asteroid's own orbit, the fact that it might be getting closer to the Earth and speeding up its motion across the sky or getting farther from the Earth and slowing down its motion, we can't use the approximation that they go in a straight line at a constant velocity anymore. But the power of the HelioLinc algorithm comes from an idea that was originally published by Matt Holman at Harvard, Harvard Smithsonian in 2018. And his concept was, if you guess how far away the object is from the sun, then assuming your guess is right, you can get its motion in quite a bit of detail from the observations that you have from Earth. And so the idea is that we take in a lot of data at the same time, say two weeks worth of data, and the data is just millions of measurements per night of individual things in the sky that might be asteroids, things that are not stars, that are not there all the time. And we sort that data into pairs, so things that we're seeing twice on a given night that are close enough together that they could represent the same object. So an asteroid could move from position A at time A to position B at time B on some kind of reasonable trajectory. And so we find millions, even hundreds of millions of those candidate pairs. And then for each pair, if we guess how far away it is from the sun, we can calculate its total motion in the Solar System. And based on that guess we can figure out which pairs from different nights could go together. So for example, if I have a pair of observations from September 21st and another one from September 23rd and another one from September 24th, I might say, wow, if the object was exactly 158 million miles from the sun, then the motions for all those pairs line up perfectly. And so one object at that exact distance would have had a trajectory on the sky that exactly matches those three pairs. And so that's the way HelioLinc works. We guess distance from the sun and we interpret all the pairs of observations as if that distance is correct and we find ones that line up perfectly or very close, very accurately at that distance. And then we sort of store that information, these were the good pairs for that distance guess, and we move on to another distance guess through thousands of different guesses. And of course, we try to arrange the set of guesses so that by the end we've guessed every distance that a near-earth asteroid could have and hopefully linked all of them that were in the data.

Sarah Al-Ahmed: See, now the name of the algorithm is beginning to make sense, HelioLinc3D. I was trying to figure out how is this connected to the sun? And that makes perfect sense.

Ari Heinze: Yes, that was a major insight or a breakthrough by Matt Holman in that he realized that the motion of an asteroid as viewed from the sun is much simpler than it is as viewed from the Earth. And so if you make a guess about its motion relative to the sun, you can get by with a manageable set of guesses in a way that you couldn't if your reference point remains the Earth.

Sarah Al-Ahmed: That's really clever, and you bring up a great point, which is that this wasn't just your team working on this. There've been many different universities and people working on this over time to try to help out. How many different people are involved in this project?

Mario Jurić: For Rubin, it's hundreds. To be honest, I actually don't know the total number. We're talking about something like a dozen universities and national labs that have been working together to build this telescope. The data management team alone, this is our folks who are writing and thinking about software. The data management team alone had at one point over 100 people involved one way or another. This is currently the largest nationally funded project in astronomy, and I heard as of a couple of years, it was the largest project NSF has ever directly funded in all of sciences. So it's quite an endeavor.

Sarah Al-Ahmed: Wow. Even more than Arecibo. Thinking back on that, that's wild.

Mario Jurić: Yeah, it is. There's this interesting little facto and Rubin, usually when you build a telescope, there's a certain cost you expend on the telescope itself. So imagine the mirrors, imagine the steel that goes into the mouth and so on, and then there's cost for the instruments. But now we also have to start thinking about the software because it's not sufficient anymore to just build a telescope, put a great camera on it, and only the astronomers use it because those cameras can generate so much data today. So you have to build a full-blown software system that's going to be able to "look at these images" to make those data useful in any way. So now instead of just building a telescope and the camera, you have the software system that is as complex and as costly and as big as the other two more traditional components.

Sarah Al-Ahmed: We'll be right back with the rest of my interview with Mario Jurić and Ari Heinze after the short break.

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Sarah Al-Ahmed: As you've been combing through this ATLAS data with this algorithm. This was just the first detection of a potentially hazardous asteroid, but have you found any other cool things with your algorithm so far in that data?

Ari Heinze: I haven't found any other near-earth asteroids that were not already known. I actually found dozens of already known ones and in each case I was sort of hoping this would finally be it, this would be the discovery. But that's actually a challenge with using the data from a very effective, powerful, ongoing survey like ATLAS in that they take four images per night. They really have state-of-the-art software that is designed to find every asteroid that shows up four images per night. And it's not just ATLAS, there's several other surveys operating that can recover and confirm detections by ATLAS or have ATLAS confirm their own detections. I had to find something that slipped through the cracks of what is actually a very efficient system in order to actually have a discovery that was made with HelioLinc and not preempted by any of the currently operating and also very effective algorithms.

Sarah Al-Ahmed: That's a challenge though. I'm guessing that you're going to need to at least keep running this algorithm through a few more bits of data to fully prove that it's ready to go.

Mario Jurić: Yes, we will continue running this algorithm both on existing data and on LSST simulations. But really now I think the big next step for us is actual Rubin data. So that will start flowing in about a year internally. That's when we get first images and we'll spend then about a year of doing tests. And I think I am 99.9% confident we're not going to be surprised that Ari's code will work as phenomenally well as it has been so far, but in about a year we'll know at 100%.

Sarah Al-Ahmed: And did you have to do any follow-up observations to make sure that this was actually a true detection of a potentially hazardous asteroid?

Mario Jurić: So there's an interesting story behind that as well, because the moment Ari identified it and reported it to the Minor Planet Center, they were able to find fragments of observations from other surveys that weren't recognized as this object, as belonging to this asteroids and quickly basically confirmed it. And we then ran another code called ADAM Recovery built by another nonprofit called B612 Foundation Asteroid Institute that then uncovered eight more observations. So the moment we had a clue where to look, it all kind of fell into place.

Sarah Al-Ahmed: Does this give us some clue that maybe we should be giving this algorithm out to other surveys and other people that might be able to use it? Because it sounds like there's a lot of data that's just waiting to be figured out, but in this case, maybe you saw it three times instead of four.

Mario Jurić: Yes, yes, yes, definitely. So one of the things that Ari and I are trying to do is build a service that would run on the web where you could upload your observations and then we will run HelioLinc on them. And then you can imagine going one step beyond that because once you have a place where data are being uploaded, you can run not only our code, but you can run any code that anyone in the world comes up with or contributes because there may be things that slip through our nets, but a different kind of code catches them. So we're imagining maybe a few years from now, having this hub where it's possible not just for existing surveys, but Rubin as well, to upload their data and to have a multitude of codes developed both by professionals and amateurs running to find asteroids. I think it'll be really, really fun to see what's going to come out of all of that.

Sarah Al-Ahmed: Yeah, that would be immensely helpful. I'm sure there's all sorts of things that are just hiding in that data that we haven't detected yet. Let's actually talk about this asteroid now that we know that you've found it. It's called 2022 SF289. It's a potentially hazardous asteroid. What kind of criteria is required to classify an asteroid as potentially hazardous?

Ari Heinze: So there's two criteria. One has to do with how close its orbit comes to Earth's orbit, and the other has to do with the size. If it's small enough, then it doesn't count as potentially hazardous. And the orbital approach distance is 0.05 astronomical units, which is about 5 million miles or 7.5 million kilometers. And that just means that the closest approach of the Earth's orbit to the asteroid's orbit has to be that distance or less. It doesn't mean the asteroid has actually passed that distance from the Earth because the encounter distance, the actual distance between the Earth and the asteroid at a given moment in time, that can only be as small as the minimum orbital intersection distance if the two objects arrive at the closest point in their orbits at the same moment. That distance between the orbits, which is called the minimum orbital intersection distance or MOID, that's the maximum close approach. It can't come any closer than that in its current orbit, and that has to be less than 5 million miles or 7.5 million kilometers. And then on the side side it has to be 140 meters or bigger approximately. It's actually a brightness cut technically, but that brightness corresponds to the size of about 140 meters.

Sarah Al-Ahmed: What kind of damage could an object of that size do if it actually hit the Earth? Not to say that this one will, it's just a potentially hazardous asteroid. It's not going to hit us anytime soon, but if it did.

Ari Heinze: So I'm not an expert on that, but there are things I can say. So one comparison would be the 2013 Chelyabinsk impactor over Russia. That was a estimated 20-meter object, so much smaller. It didn't kill anyone, but it did many millions of dollars worth of damage, mainly in the form of broken windows because it exploded with the energy of a hydrogen bomb, but much higher than a hydrogen bomb would explode. It exploded tens of kilometers high, I've forgotten the exact height. So that was a tiny object compared to the minimum size for potentially hazardous objects, and it still did a bunch of damage on the ground. But the damage was mostly just a windows broken by the shockwave of this very powerful but very high altitude explosion.

Sarah Al-Ahmed: That's a good thing to know though, because if an asteroid does come in, you see a bright flash, maybe step away from the windows for a little while just to see because that shockwave takes some time to get you. And I know that no one died in that impact, but several people were hurt by the glass blowing out of their windows all over the city. So that's a survival guide tip for anybody out there if there's an asteroid coming our way.

Ari Heinze: Yes, absolutely. Yeah, if you see a bright flash, the shockwave will probably arrive about a minute later. Don't stand by a window and maybe put a pillow over your ears. That would be a good safety measure too, I think. So that was a tiny asteroid, didn't count as potentially hazardous. The Tunguska impactor of 1905, I've forgotten the date. That was probably more like the minimum size for a potentially hazardous asteroid. And that leveled something like-

Mario Jurić: I think about 40 kilometers-

Ari Heinze: 40 kilometer radius of Siberian forest.

Sarah Al-Ahmed: Which of course is why we celebrate Asteroid Day every year. That was the anniversary of the Tunguska blast. That was just devastating. Thankfully no one lived in that forest, but the whole forest got flattened.

Ari Heinze: Right. So that's sort of what we might expect from the minimum size, potentially hazardous asteroid is a Tunguska-like event. So the evacuation zone should be maybe 100 kilometers in radius, if not more if we couldn't deflect it. Which with the amount of warning that Vera Rubin should give us, we probably would be able to deflect it.

Sarah Al-Ahmed: We'll just have to create a whole set of dart-like spacecrafts just waiting to be launched up there for just such an emergency. What else do we actually know about this asteroid now that we've detected it?

Mario Jurić: So I think the most important thing we know is that it's not a threat. It does come close to the Earth's orbit as Ari explained, but for the foreseeable future, a few hundreds of years out, we know that it will not cross paths with Earth and actually impact. The reason why it's interesting is just because of how we found it and that it shows that we can now find asteroids with much less data than we used to need before, and that's how we're going to find them with Rubin. But otherwise, and this is kind of the story for almost all of these objects, they're interesting for that one or two nights when you discover them where you're still uncertain where they're going to go, and the second you get more observations that tell you whether this is a threat or not, then they either become very interesting or you simply put them in a drawer and then move on. We hope that with Rubin, all of the asteroids we find that look like this, every one or two days we should be finding one of these with Rubin on average, we hope that they all end up in a drawer. That none of them turns into something where we really need to mobilize that system that our colleagues in NASA and elsewhere are developing to actually go into a defunction.

Sarah Al-Ahmed: That's part of why this field is so important and why so many people can contribute to it, honestly, because each and every discovery adds to a larger whole that can literally help us save the world. But that one little discovery might just tell you that a rock is going to fly between us and the moon and then you don't have to worry about it anymore. But we still need a robust system to detect these and people all around the world to give their time to it because one bad day, one bad asteroid can make a huge difference.

Mario Jurić: And I think that the beauty of this work is that it's really a massive worldwide collaboration, not just between space agencies and science agencies and observatories of professional astronomers, but of amateurs as well. Some of the most prolific observatories who do follow up, so who do that second and third observation once a potentially hazardous object is found, are actually run by amateurs and in some cases staffed by college students and high school students. And it's wonderful to see how it's possible to contribute in this system and how all the data, when they're put together, essentially lead us to a world that's safer, where we know that we don't have an object coming towards us.

Sarah Al-Ahmed: It's part of the beauty of citizen science, and there are some really wonderful places online that people can go to actually help out in this research. And if asteroid detection isn't your thing, you can help with planet hunting, finding life in the universe. There's all kinds of wonderful projects that you can contribute to.

Mario Jurić: 100%.

Sarah Al-Ahmed: And I wanted to say, Ari, as I was reading the article about this discovery that came out in the University of Washington's online website, there was this really beautiful video in there that I think summed up this discovery very well. And I think Ari, that you voiced it over, but the beginning had this not so subtle nod to Carl Sagan's Pale Blue Dot speech at the beginning. And I just wanted to say I thought that was a beautiful way to contextualize why this work is so important.

Ari Heinze: Yeah, I'm glad you enjoyed the video. That was fun to record. It's something that should bring us together as the human race that we are all in this together when it comes to the asteroid threat. No one is excluded from the threat, and if we can avert it, then we've helped everyone in the world, whether they like us or we like them or not. We're all in this together.

Sarah Al-Ahmed: I've been reflecting on that pale blue dot feeling a lot recently because I was very lucky last week, Mat Kaplan, the previous host of the show, and several of my colleagues and I went to go meet with Ann Druyan who was our co-founder, Carl Sagan's wife. And that was a very beautiful moment for me. And every time she opens up her mouth to talk about our place in the universe in protecting Earth, it's just a profound and beautiful thing.

Mario Jurić: This is the one planet we have. We have to do our best not to end up like the dinosaurs.

Sarah Al-Ahmed: So now that we've established that bettering these algorithms can help us find asteroids that are potentially hazardous, what does this tell us about the future of planetary defense, especially in an age where AI technology is just blowing up on the internet? What does the future of planetary defense look like?

Ari Heinze: It's interesting that technically HelioLinc is not AI. None of it was actually machine learning, it's all just math. And I do enjoy that kind of algorithm because if it doesn't work, you know exactly why. Whereas with AI, because it's a learning adaptive thing, you can be not sure how it will work. But I think there is a lot of synergy between what you might call deterministic math like HelioLinc and AI. One example of that would be something I did back with the ATLAS project where Larry Denneau, one of my bosses out there and a brilliant software engineer, he wrote a machine learning AI type analysis of the little postage stamp images that we cut out of the ATLAS images around each candidate asteroid. And so his system would analyze that to see if it was real or not. So it was a machine learning, is this a real asteroid or is this some kind of image junk like a cosmic ray artifact or something like that? And I had also written a deterministic code that we called VAR test for a variable star test that used a bunch of pixel math to do the same kind of analysis. And it turned out that VAR test was pretty good and the machine learning was pretty good and if you put them together, if you use both of them, then you've got better performance than either of them could do alone. So I think there's synergy between what you might call natural intelligence, the math that humans have derived over many years that we can put together into deterministic programs where we know what it's going to do, we can control exactly what it's going to do, and then the artificial intelligence where it's really learning. The computer is learning characteristics of the data, and we can't predict ahead of time exactly what it's going to do. And I think it's important to keep both things in mind that just because we have AI doesn't mean that we don't want the deterministic algorithms and the clever math that people have derived over the centuries. We can use both in parallel.

Sarah Al-Ahmed: We survived a long time without ChatGPT, so we will be okay, but I really love that we're on this cusp of not just having better ways to analyze this data, but better instruments to do so and a wider network of sharing for these algorithms and the data because this is going to give us a more clear picture of what's going on in our Solar System. And someday if we save the world, literally save the world, it'll be because of you and the telescopes and all of the asteroid hunters around the world. We'll have to throw a serious party on that day

Mario Jurić: Or maybe one of your listeners here. I think one of the big opportunities in the next 10 years with all these large telescopes coming online, us with Rubin and say NEO Surveyor is there's going to be so much data out of there, and we're not going to be data limited anymore, but algorithm limited. So if there's someone who's passionate about space, passionate about astronomy, about planetary defense, who comes more from an applied math background or a software engineering background or AI background who's interested in tackling challenging algorithmic problems like this connecting the dot problem we have with asteroids, this is a wonderful way where they can contribute. All these data will be available and it'll just be up to how clever of an algorithm we can come up with as humanity, just how effective all of this is going to be. So I think there's a lot of opportunity for citizen science here as well.

Sarah Al-Ahmed: Absolutely. Well, thanks for joining me both Mario and Ari. I'm so excited for this observatory to come online and for everything it's going to do for us. And I'm really glad that we have a new algorithm that we can apply not just to this telescope, but also to all the others. This is going to be really cool.

Mario Jurić: Yeah, thank you for having us.

Ari Heinze: Yes, thanks for hosting.

Sarah Al-Ahmed: I've said it before and I'll say it again, not all heroes wear capes. Some save the world with observations, algorithms, and science. We owe it to the non-avian dinosaurs and honestly to all life on Earth to do everything that we can to protect our planet from asteroid impacts. As our co-founder Carl Sagan said, "It underscores our responsibility to deal more kindly with one another and to cherish and preserve the pale blue dot, the only home we've ever known." Defending Earth from impacts is one of our core enterprises here at The Planetary Society, and one of our greatest champions in the effort is our chief scientist, Bruce Betts. Let's check in with him for what's up. Hey Bruce.

Bruce Betts: Hey, Sarah.

Sarah Al-Ahmed: I'm always happy to talk with people who are trying to save the world from asteroids, and I feel like of the people out there that are trying to do the most to save the world, you're one of the people that pops up in my head because of all your work with our Shoemaker NEO grant program.

Bruce Betts: Well, thank you. I certainly have been working on it for 20 years or so. Obviously I'm just one tiny piece of a very large puzzle with a lot of people doing great stuff. But our Shoemaker NEO grants, we've been able to fund a whole lot, meaning over 70 different grants over the years to over 20 different countries to mostly so-called amateur observers, but they're really way crazed, highly technical, producing professional level results, and they're doing important, particularly follow-up observations to figure out orbits and also the characterization to figure out physical properties, things like that. But we've got, especially in the Southern Hemisphere right now, we've got some sites that are doing a fair amount of discovery, including the top discoverers in the world right now, except for the three big NASA surveys, and they operate out of Chile. But we've got a bunch of good stuff. It's amazing what they've accomplished. We also sponsor a NEO-related program through our STEP grants program. One of the first STEP grants was a study of near-earth asteroids. And we've talked about that before, and I won't go into detail, but it's important. We got to find that stuff. And of course, we're also about education of the asteroid threats. So thanks Sarah for helping out.

Sarah Al-Ahmed: It's nice to be a part of it because, I mean, maybe it's just that I watched too much Armageddon and Deep Impact as a kid, but I always felt like this was something that was a real threat and I was so worried as a child that no one was going to do anything about it. And then I grew up to learn that there are many people around the world working on it, and in fact, it's a colossal global effort. So that makes me feel safe.

Bruce Betts: But it's really changed over... As I say, I've been heavily involved for about 20 years since I came to The Planetary Society, and it was a much, much smaller effort. There's still an awful lot to do in a lot of things to find and a lot of techniques to develop. There's no shortage of work, but it's been great to see the community grow from a few tens of people to a few hundreds of people. And the funding overall massively increase, especially from NASA, partly through our efforts, but largely through a broader set of efforts to increase funding for the program. It's one of those things that's tough to get people's attention, but that's the other thing is the so-called giggle factor has gone down. People are less likely to laugh at you when you're say you're working on that now and go, oh, that's really good. Because if we don't do something, the probability is, let's see, 100% that we'll have a dangerous impact. And the question is when? And we don't know, so we will... So hey, go out there and support planetary defense efforts because they're really important. What do you think, Sarah? Do you think it's a good idea?

Sarah Al-Ahmed: Yes.

Bruce Betts: Okay, perfect.

Sarah Al-Ahmed: It's a very good idea.

Bruce Betts: All right, that was my random space fact for the day. I was just going to ask you.

Sarah Al-Ahmed: What do you think Sarah thinks about this one thing? But I did want to ask you something because they brought this up in the interview. How much do you think the impact the Chelyabinsk incident had on the funding for this?

Bruce Betts: It was significant, at least in the US and European programs. There already was significant increase, but that, especially near the time it happened, he could really point to it and go, look, this isn't something that is just a theoretical. This is a thousand people who got hurt in a real airburst impact. And that was on the small side. So no, it was definitely helpful. I don't have a quantitative answer for you because it would be pretty impossible to obtain, so thanks for arranging that if you had something to do with it. No, I'm kidding.

Sarah Al-Ahmed: It is totally me. That and Apophis is mine.

Bruce Betts: Apophis is good that I don't want people arranging impacts that actually hit, but Apophis, it'll fly by in 2029 closer than geostationary satellites is a good example of something that has and hopefully will get people's attention because that's a serious asteroid that's around 300 meters diameter. That's regional disaster if it hits. And it won't, but it's saying hi.

Sarah Al-Ahmed: It's going to terrify a bunch of people as it soars really, really close by our planet, but thankfully not hit us. So thanks to the asteroid hunters that found that guy. All right, what is your actual random space fact this week?

Bruce Betts: My random space fact. Chandrayaan-3. Hey, congratulations for landing on the moon. Excellent job. They've gotten a lot of press, which is great, but a lot of it said they landed at the South Pole with the Vikram lander and the Pragyaan rover, apologize for mispronunciation. And indeed, they were the highest latitude successful soft landing on the moon ever. But I was curious, I was like, is it really? No, it's around 69 degree. My dog's trying to correct me. You're right. It's 69.367 degrees south is in their initial take on it. So still very much they said polar regions, I wouldn't even question it is a big deal that it's down there, but it made me wonder. And so that's half of the random space fact, what they did, but the other half is what was the closest to the pole? Well, that was the closest successful soft landing, but the highest latitude impact mission on the moon was the Chandrayaan-1 Moon Impact Probe, the MIP, which was in 2008, and they were at 89.76 degrees south, so pretty much at the South Pole. It was designed as an impactor, so was not an accidental crash. It was intentional it's impact, and learned things from that. And they then named where they landed, which is part of the Shackleton impact crater complex. And again, I'm sorry if I mispronounce it, Jawahar Point, which was named after former Prime Minister Jawaharlal Nehru because his birthday was the date that they hit. But I noted at the risk of being inappropriate for just a moment, it's also my birthday, so that's a point.

Sarah Al-Ahmed: So you need a point on the moon named after you really, but I guess we'd have to impact something into the moon to earn it.

Bruce Betts: On my birthday, yeah. No, I don't actually claim that, but that's my third part of the fact, is they hit on my birthday in 2008. It was, thank you. Happy birthday.

Sarah Al-Ahmed: That's a good present.

Bruce Betts: It is. Anyway, great job, Chandrayaan-3. It's impressive India getting a successful land around the moon and down in the South Pole regions for the first time.

Sarah Al-Ahmed: Yeah, this kind of mission can make a big difference. The more we know about the water down there at the poles, that could change everything when it comes to human exploration in the future. I wanted to share this comment with you because this was actually something that stuck out for me in a previous conversation I had. It was in a show last week. We were talking about the slow evolution of Europa and one of our listeners, Sabine [inaudible] from Austria wrote in to say, "I was blown away by the hypothesis that Io may have had an ocean in the beginning. That's a fascinating thought." And I think of all the things we talked about in that conversation, that was the one that threw me for the biggest loop too. Can you imagine if Io had an ocean and then the whole thing got blown off by Jupiter and now it's just the most volcanic ball of volcanic volcanic anything? It's terrifying.

Bruce Betts: I wondered what emotions you were associating with it. I would go fascinating, but yeah, I suppose. I suppose, yeah.

Sarah Al-Ahmed: I had this nightmare once. This is actually true. I had a nightmare that I was standing on Io and water was pooling around my feet for some reason, and there's volcanoes in all directions. And I looked up into the sky and there was just Jupiter staring at me. I don't know how to describe it, but to this day, I still feel like Io is one of my favorite moons just because that dream terrified me.

Bruce Betts: I hope that you have only happy, sweet, wonderful dreams about planetary things. Is there anything that you received from any of our listeners that might help you?

Sarah Al-Ahmed: Maybe like a good bedtime poem? We got a poem from Jean Lewin who's referencing our August 2nd episode about the subsurface granite on the moon. He wrote, "For a decade, it perplexed us, but an update was in store. Through the use of microwaves, we may have opened up a door. Collected through orbital data, how did this lunar process evolve, presenting us this question that we now try to solve? A hotspot Compton-Belkovich on the far side of the moon, between two random craters, vulcanism here has bloomed. Subsurface granite formed on Earth volcanically, but without water or tectonics, a riddle of geology. Could this be from a pluton or a batholith? We spy bubbles of lunar magma 50 kilometers or so wide. We know the lunar near side, its crust is not as deep. And though it's a bit thick-skinned, the far side too has KREEP."

Bruce Betts: K-R-E-EP. That was pretty amazing, and I'm glad you enjoyed the word batholith-

Sarah Al-Ahmed: Batholith.

Bruce Betts: I always enjoy that.

Sarah Al-Ahmed: Yeah. See, I almost said bat lith when we were having that conversation. All those lunar magma tubes full of bats.

Bruce Betts: Wow. Okay, now I will be having nightmares about space, thank you. Thank you very much.

Sarah Al-Ahmed: You're welcome.

Bruce Betts: That's all I can think about. All right, everybody go out there looking at night sky and try not to think about being in a lunar lava tube with a bunch of bats. Thank you. Good night. Sleep well. Sweet dreams.

Sarah Al-Ahmed: We've reached the end of this week's episode of Planetary Radio, but we'll be back next week with even more space science and exploration. Planetary Radio is produced by The Planetary Society in Pasadena, California and is made possible by our Earth defending members. You can join us as we support the asteroid hunters; missions, observatories, and algorithms that keep our planet safe at Mark Hilverda and Rae Paoletta are our associate producers. Andrew Lucas is our audio editor. Josh Doyle composed our theme, which is arranged and performed by Pieter Schlosser. And until next week, ad astra.