From First Principles - Can We Stop an Asteroid? The Physics Behind NASA’s DART Mission (EP. 30)

Episode Date: March 16, 2026

Hosted by Lester Nare and Krishna Choudhary, this episode is a full deep dive on planetary defense. We break down NASA’s DART mission, why the goal was never to “blow up” an asteroid but to gently nudge it, and why the newest result is even bigger than the original headline: scientists can now directly detect that the Didymos–Dimorphos system changed not just locally, but in its heliocentric path around the Sun.Summary DART actually worked — not just by shortening Dimorphos’s local orbit around Didymos by 33 minutes, but by measurably changing the motion of the whole binary system around the Sun. Planetary defense is a measurement problem — the new result hinges on detecting a velocity shift of just 11 microns per second in an asteroid system moving tens of kilometers per second. Why ejecta matters — the impact transferred more momentum than the spacecraft carried in, thanks to debris blasting off the asteroid and boosting the total deflection. Why this matters for Earth — for the first time in our planet’s history, life on Earth may actually have the tools to alter its own cosmic fate.Support the showDonate: FFPod.com/donateFollow: @FFPod on X / Instagram / TikTok / FacebookChapters 00:00 New single-story format 01:53 DART mission setup 18:26 Why the binary asteroid system matters 31:36 Measuring the heliocentric deflection 46:28 Planetary defense implications 53:37 OutroShow Notes DART heliocentric deflection result — Science Advances NASA DART mission overview ESA HERA mission

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Just steps from the water. The Hilton sale is on now. Book on Hilton.com or the Hilton app and save up to 20% to get the stay you expected. When you want savings, not surprises. It matters where you stay. Hilton for the stay. Hello, internet. This is your captain speaking. Lester Nare, joined as always by my co-host and our resident PhD, Krishna Chowdhury. Today we have a wonderful episode. We're going to do a story, a research paper on planetary defense, covering one of NASA's most audacious missions, the Dart mission. Spoiler alert, it worked. But where it gets interesting is in the how and the why.

We're going to take a quick pause here to talk about a slight change to the programming. For many of you who have been listening to us for quite some time, you know that we do weekly episodes, and the demand has just been insane for us to do more. So what we're going to try out here is actually doing multiple episodes a week, but having our episodes be focused on a single story. So today, we're going to just be focused on the DART mission with planetary defense, but you will see our faces two more times this week with a follow-up story, and we will have the rundown be its own episode type. And I have some ideas about some game show elements to test our resident PhD.

As always, we are going to learn about the science from the ground up today, because this is from first principles. So, if there is an asteroid coming to Earth, I would like to not die. Armageddon, Deep Impact. Yeah, all of these, I would like that not to happen. Yes. Okay? And it turns out the best way to have that happen is actually not to, like, blow it up,

but to just gently nudge it out of the way. Gently because, you know, it's a giant asteroid. You got to get a little aggressive because it's a giant asteroid. But at the end of the day, all we have to do is gently nudge it out of the way, and maybe it'll avoid Earth, okay? And the first time that this happened was on September 26th, 2022. This was NASA's double asteroid redirection test. I was watching it live.

This was the Dart mission. It collided with a moonlit of a two asteroid system. Okay. And I remember watching it live. You could literally see there was a little satellite that acted like a projectile, like a missile. And it had a camera on it. And it was taking a photo of the moon. as it was getting closer and closer and closer.

And when it finally hit, the other satellite took photos of it. It hit this moon at 14,000 miles per hour, which is about six kilometers per second. And the key result that we got immediately was that the orbit of this moonlit, the name was dimorphous, orbiting around didomus. The orbit of that moon around the main big asteroid had reduced, by 33 minutes. Okay. So it went from something like 12 hours to 11 and a half hours. So the contact changed the trajectory, the path that this two moonlit system was traveling on.

Yeah, but so the contact changed the orbit of the two moonlit system. The orbit. That's what we could confirm. Okay. What you're saying is what this paper is about. I see. Okay, which is I ran into the moon and now the orbit has changed. Yes.

But what does that do for how this moon, this two asteroid system goes around Earth? Because the orbit you're talking about is locally. Yes, exactly. And getting that signal is super easy. 30 minutes less than 12 hours. That's what, like a little bit less than like 5%. Right? That's a change that is doable, like pretty immediately,

especially because we've got the Dart mission in that asteroid system that's like monitoring the two going around. Right. So getting that data. data is very quick. Happened in 2022. We got that confirmation within, I think, like, a month. Okay. Okay. This is now, what, four years later? Three and a half years later. And now we have a paper that's out in science advances. And it confirms that there's a measurable change in the berry center of that two moon system going around the sun. Meaning those two asteroids now have a different orbit around the sun itself because of that crash on its moon.

Does that make sense? It makes total sense. And I want to briefly talk about why the implications of something like this are so historical. You know, Earth has been around for four billion years. Life on Earth has been around for hundreds of millions of years. Yep. Some simple life billions of years. Yeah.

And in the entirety of that time period, the life on Earth has never had control of its own destiny. Yeah. As it relates to celestial eyes. and their impact on the planet. So what you're suggesting is that humanity, for the first time in the four plus billion year history of Earth, has finally enabled itself to have agency on its cosmic destiny based on these objects potentially coming in to impact us.

Exactly. This is a very interesting story for us to understand. Yes, yes. And I just want to say a quote from the lead author of that paper. He said, if an asteroid is ever on its way to hitting the earth, we can more confidently now say that we have the ability to push them around and away from Earth. This was by the lead author Rahila Makadia from the University of Illinois Urbana-Champaign. And can I just say the news article where this quote comes from, they quote him as a planetary

defense research. When I was in grad school, on my CV is written graduate student. researcher. This guy can write planetary defense researcher on his CV. How sick is that? That's so awesome. Right? All right. So, as you said, let's get into the history and why this is so important. The threat comes from these things called near-Earth objects. This is an animation showing all of the near-Earth objects that we've ever seen. The blue circle or the, you know, the blue orbit in the middle, that's the Earth. Okay. And look at all of these dots. Yes. All of these dots are threats to us.

For those who are listening and not watching the pod currently, there are thousands, hundreds of thousands of these objects in near Earth orbit. It's actually a very nauseating amount. Yeah, yeah. It's actually quite concerning, right? Because if you look, like, let's just linger on this animation for a second. The Earth's orbit, there's already a bunch that are sharing Earth's orbit. Yes.

Right? Then you see there's a faint line. where Mars's orbit is, that's the red line. And then there's this giant belt, almost cloud of orbits. That's the asteroid belt in between Mars and Jupiter, right? Those are also threats, not just the ones that are near right in Earth orbit, but you can imagine like some random gravitational anomaly, like Jupiter pushes one of these asteroids out of the way,

or these two asteroids get a little bit together, and then they get nudged into the inner solar system. Exactly. It's like in a car accident. you're changing lanes and you sidestwip the car next to you. Yeah. And then they're now sidest wiping the car next to there. And then there's an 18 wheeler behind. Like it can get bad really fast.

Really fast. Right? Similar to the Kessler effect when a satellite. That's right. Crashes in orbit and it basically creates catastrophic failure for everything because there's just these little things flying around. Yeah. And it's going to impact everything else.

Yeah, exactly. And any momentum transfer can be really bad. Yes. Right. And Hollywood is obviously obsessed with this. We've got, as you were mentioning, Armageddon, deep impact

I can't think of many more Oh don't look up is a big one That's the most recent one That was more about like climate change Yes but it would still like the metaphor Was really funny and at the end of the day The literal movie is about a comet That is coming into earth

And nobody believes the scientists So this has actually happened In human recorded history 1908 was the Tunguska event In Siberia It was a 50 to 80 meter object And it burst 10 months miles above the surface. So it didn't even make contact with the earth. It exploded because it was

heated up by so much. And it flattened 30 million trees over hundreds of kilometers squared. Fortunately, it was in the middle of nowhere in Siberia, right? But imagine if that happened on a population center. Yeah. It would be way, way worse than Hiroshima Nagasaki. Yes. In 1980, there was the Alvarez hypothesis, which was linking the Cretaceous paleogen extinction, which is the extinction of the dinosaurs 66 million years ago, it linked that to a cosmic impact. In 1991, the Chiksa Club crater was discovered in the Yucatan Peninsula because a bunch of oil companies were charting the gravity, the specific gravity around the Yucatan Peninsula,

looking for oil, right? And so in order to look for oil, what you want to look for is like low density packets. under the earth's crust. And one of the best ways to do that is to literally just measure the acceleration due to gravity. The thing that we learn in high school being 9.8 meters per second squared, well, if you go 9.8, 1, you know, all of the little digits, the little tiny deviations of that acceleration due to gravity, if it's a little less than normal here versus somewhere else, that could mean that there's a low density packet underneath the ground, which is why it's not pulling on whatever object that you're using to measure that acceleration. So oil companies were doing that. They actually found a ring of high density. Oh.

And that ring was the size of the Yucatan Peninsula. And it was this primordial crater from 66 million years ago. I have one clarifying question. When you mentioned like low density pocket, what you're referring to is like a lake of oil under the ground. Exactly. Okay. Yeah, yeah. Instead of rock.

Instead of rock. Right? The oil is less dense than rock. And so what they're looking for is an underground. lake of oil. Exactly, yeah. And that underground lake of oil would decrease the effect of gravity in that location. So if you were to measure gravity very, very precisely, you'd be able to chart out where the oil is. That makes sense. This is also why science is so important to capitalism. Yeah. Because the alpha matters. The alpha matters. And like the, you know, the closer you get to this

precision, the more you can unlock, you know. And then finally in 2013, there was the Chelybinsk's Meteor, which was a 20 meter object. Over a thousand injuries. It happened also over Russia. Yes. And this was one that was very, there was video, like, you know, it was very, because we had media and technology and devices, it's probably the most prominent,

atmospheric, large object atmospheric breakup explosion. And over a thousand. I mean, it was a lot. It was a lot. It was a lot of broken windows and things like that. one of the reasons why we have so much footage on that is because the Russians love having dash cams. Yeah, yeah. Because, I don't know.

I mean, I don't want to say anything. Comment in the thread if you know the reason why that's true. Yeah, yeah. But anyways, Russians love having dash cams. And so there's so much dash cam footage of the meteor just like coming down, right? It's pretty incredible. I want to just reemphasize that that 2013 meteor was only 20 meters. Yeah.

And I guess diameter. Yeah. It's not a super large object. No, no, no. And the size of a house. The force and the impact. And the thousand, because the devastation was pretty severe.

Yeah. Right. So in any event. So our best strategy when it comes to planetary defense is actually to nudge it. We want to give it some momentum and then we want to get out of the way. And hopefully that thing gets out of the way, right? Because we've nudged. it and it just avoids earth. It keeps going around the sun, but now it's, or orbit has changed a little bit.

In the same analogy of the car accident, like before, imagine you're in a James Bond movie, and James Bond is in a car in the left lane, and the love interest in that movie is handcuffed to the steering wheel in the car in the right lane, and they're both going 90 miles an hour down a road, and the right car is about to hit something. He's like, well, let me just bump it out of the way, because that'll change how it's driving out of the way of about to hit this brick wall that's in front of us. Just as like a grounded analogy. Yeah, yeah, yeah.

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Whatever needs to be done for your thing, Canva can make it in each. even better and bigger thing. Canva, the thing that makes anything a thing. Yeah, he had a lot of detail in that one, guys. Yeah, but that's exactly right. We want to just nudge it, get it out of the way. Okay, in 2022, that was the DART mission. It was the first intentional deflection. It was actually launched out of Vandenberg in 2013, which is right down the street of Southern California. It went with the Earth to meet up with this double asteroid

system. So this double asteroid system, which is didimus and dimorphis, so we can look at an animation of their orbits, right? The green is the double asteroid system. The teal is Earth. Yes. And the pink is what we're seeing of

the our, like, what you're going to call it? The Dart Mission. The Dark Mission itself. Okay, sorry. So let me just recap. The Blue is Earth. Yes. The Dart Mission comes out in pink from Earth. It's following Earth, as you can see. It's just leading it a little bit.

Yes, yes. And the green double asteroid system that we're trying to hit is going to come meet up with us. The double asteroid system is actually a near-Earth orbit, and there you go. Yep. That's when the impact happens.

You can tell that the impact is happening pretty close to Earth, because both are moving together, and then the impact happens here, but Earth is pretty close. Yes. That is by design, because what we want to do is we want to have all of the observatories on Earth looking at this thing to get as much data as possible.

The impact was like 6 million miles, which in the grand scheme of things is not that far away. I want to just pull this back up really quick, this animation. Because I think what's so interesting is when you look at where it launches from, the launch of Dart happened on the opposite side, like it first left Earth, on the opposite side of the sun from where the asteroid was coming in. And it did almost a three-quarters orbit prior to contact. And I just want to, the distance, look, if I'm trying to throw a paper ball,

a paper towel ball into the trash can from my desk, I'm maybe going to hit it six times out of time. We're trying to send this thing in an orbit. Around the sun. Around the sun. With the earth. With the earth. Millions of miles.

Yeah. And it made direct contact. I just want to really emphasize the... It's level of precision that is required to... Because that's not the point of this story per se. It's the second piece. But that initial part in and of itself is an exceptional piece of just both the engineering,

the math, and the operational planning to execute on. Yeah, I mean, NASA's just incredible at doing this kind of stuff. And as you mentioned, right, like the thing gets released. it makes almost full circle. So it's almost like if it got launched in, I wish I knew the exact date that it got launched, right? But if it got launched somewhere, it's going to almost do a full year.

Yes. Around, right? Yes. Before actually getting there. Pretty incredible. So that's what we want to do, right? We want to have it impact very close, and then we want to have all of the observatories

watch this impact happen. Yes. Right? Yes. Yeah. Because we don't have a lot of impact. instruments deeper in space. And so the best way we can capture data is when it's as close to our instruments as

possible. That's right. Yeah, that's right. And before we move on, yes. Let's do some housekeeping. Yes. So housekeeping notes, again, we are testing our new format, two to three episodes a week. Each episode, when it's a research paper or a deep dive, is going to be fully focused

just on that topic matter. We are also going to do the rundown as its own standalone episode. One, so we can have a little bit of fun, talk about a variety of things, a little grab bag, think about it like the weekend update on SNL, and I am determined to make a science game show out of this with Krishna as our recurring contestant, which you can't see from the current angle. He's getting a little bit of indigestion at the thought of that. But if you are intrigued by the concept or you're a long-time listener, As you know, we are a victim like we all are to the billionaire algorithm.

So a like, follow, share, subscribe is super valuable for us to help get the show to more people. And if you are really passionate about what we're doing, it really feels your cup every day and you want to find a way to support us. We do have our donation portal at fpodd.com backslash donate. if you want to catch us on socials, so you see us casually as you're scrolling the TikToks in between cat dancing videos and whatever the next trending voiceover topic is, we are at FFP pod across all of the socials. And I believe that is the conclusion of our show notes this week. Yeah, one more thing, just for me on a personal end. So for those listening, if anyone is going to APS, the Global Summit meeting in Denver.

That's the American Physical Society Global Summit in Denver this coming week. So the week of this podcast release. On Thursday, I'm giving a talk. So, you know, if you're going, just look me up on the schedule and come check out my talk on Thursday. I'm still, you know, doing stuff and talking to people about all the research that I'm doing. And if you want to know about the research that he's doing, which is very interesting, make sure, if you're at APS, you go see it. and embarrass Krishna by asking for an autograph in front of all the scientists and academics. Okay, let's get back to the story, please.

All right, the target of the Dart mission was the Didymus dimorphous binary system. Just to show how the two asteroids compare, the moon, the moonlit that we were trying to target is a bit bigger. It's in between the Statue of Liberty and the Eiffel Tower in terms of how big it is. Didimus is like Bourge-Khalifa type in terms of how big it is like the diameter and what we're trying to

Kamikaze is the moonlit Yes the little small one Yep Okay so In during the mission actually The main dart Like asteroid or sorry

The main dart probe The satellite Yes Actually stood behind to watch this unfold And it let out A little like Comakazi satellite drone Fox 1, go.

Yeah, exactly. And so this guy's job was to go and bomb dimorphus. Let's say make contact. Make contact, sorry. I shouldn't, yeah, in today's world, let's rephrase that. We're trying to make contact with dimorphus. And the other, the mainship, the mothership, is watching this all in action. Because it wants to see what is the effect of that contact on the system.

Why binary? it's because we want rapid measurement of deflection, right? We want to, the orbit is going one way. We want to see if it's slowed down or sped up. Okay, whatever. And with a dual orbit system, it is easier to ascertain the answer to that than a single object moving. Yes, yes, exactly. And here's why.

Okay. The mutual orbit velocity of dimorphous and dynumous is about 17 centimeters per second. Okay. Okay. which means that if we were to impact some momentum, 17 centimeters per second, even for something as large as a rock, a mountain, let's say, I can reasonably try and discern some change

because I'm going at it at 6 kilometers per second. So reasonably some of my momentum is going to get transferred and then I'm going to be able to see a change. And they were able to see a change. They saw that the mutual orbit period was altered by 33 meters. And this is something that we can rapidly measure. The orbit got smaller. It got shorter by 33 meters.

And the DART system, which is monitoring this, can calculate that, measure it, no problem. Makes total sense. We sent up an observer and a probe to make contact. The initial data point that was going to be captured is, is the local orbit going to change from 17 center meters per second to something else? because by making contact, going back to our car analogy, if you're in two-lane highway and you're one car and you swerve to the right and make contact with the other car, your momentum in part will be transferred to that other car.

Exactly. Which is why then you have to see the driving scenes with like, oh, yeah, sure, scroo, to counteract the transfer of momentum. Yeah, and that's why the double system matters, right? Because like this is a small enough system where like I can make that, I can make that change discernible. 33 minutes out of 12 hours, something I can easily measure now. That makes sense.

When it comes to the big thing, now let's think about the big thing. There's the big system that's moving around the sun. That thing is moving at 23 kilometers per second. Okay? The change that my momentum is going to cause is going to be less than a millimeter per second. That's way harder to measure. Yeah. And that is what this paper is doing.

I see. This paper is measuring the big one. So let's get into some of the physics that we were talking about, right? Okay. We've got the kinetic impactor, which is this idea of a sort of satellite drone going in, making contact, and its momentum getting transferred. Now, it's not that simple because it's not a simple momentum conservation undergrad problem, okay? Okay. It turns out that when I go and make this contact at high velocity at six kilometers per second to this little moon,

that's going to generate shockwaves so the asteroid is going to ring a little bit there's going to be an impact crater and there's also going to be massive ejecta that is flying the opposite direction so imagine my hand is the moon I make contact there's going to be ejecta flying this way

it's almost like another little rocket impulse that's going the opposite direction so what I'm going to get is something called momentum enhancement the amount of momentum that gets transferred is not just how much I went in with but also how much that it threw out.

Yes. Right? Yes. And so there's this beta factor called momentum enhancement factor, and that's the ratio of the total momentum that was transferred to the target divided by the total momentum that I had. If beta is greater than one, that means that I've actually impacted more momentum than I originally had because the original object has pushed out a bunch of debris in the opposite direction. Does that make sense? Yeah. So what we're saying is we have an object.

Our objects coming in to make contact with something. This actually dovetails with the panspermia story we talked about in our last episode about impacts. Yeah. That there's ejecta. Yeah. And the velocity by which you hit something can shoot that stuff very, very far. Very, very fast. And can potentially spread life.

But what we're saying here is is the amount of stuff that gets ejected out almost creates this additional push in the direction you were already going. Yes. In addition to the amount of push that you. individually as the object was giving. Yes, and that's that enhancement. And that's the enhancement. Right, yes. And so it's really important for us to calculate what this enhancement is.

Because if, God forbid, there's an asteroid coming for us. Yes. Knowing this value of beta is going to be instrumental for figuring out how fast do I need to nudge it, right? Yes. How big of the drone does the satellite need to be in order to make contact? How much momentum am I trying to put in there? Because the momentum transfer is not just what I'm putting in initial. but it's this beta factor multiplied by the initial momentum.

So the idea here is when Morgan Freeman is in the classified room talking and someone says we have an Ellie, an extinction level event because this rock is coming and they're saying, okay, what options do we have? NASA would be able to come into the room and say because we had our dart mission where we were able to get real world data about what the momentum, enhancement factor is, we know that because this trajectory is X, Y, or Z, we're going to need to send this amount of payload at this speed because the math is mathing. Exactly.

And now we have all the parameters to make that math math. Right. Right. Okay. Okay. With the DART mission, we got a local version of beta, right? Yes. But let's do a little lesson in undergrad physics.

Okay. We're going to talk about systems and what are the? their components. Whenever we do undergrad physics, we always trying to think of what is the system that is isolated from the environment that we're trying to work with. For example, the Earth, Sun, Moon system. Yes. There's three bodies, right?

When we think about, like, you know, shooting something off Earth or we think about just tides, for example, actually tides is a bad idea because we need both the sun and the moon. Sure. But if there's stuff that's local to the Earth and the Moon, we don't really need to worry about the Sun too much. Okay. Okay. We can have momentum transfer in between the Earth and the Moon, and we'll be fine. Would satellite stuff be an example of the?

Yeah, satellite stuff would kind of be an example of that because, like, the Sun is kind of far away. It's, like, really big, but it's still, like, it doesn't, it doesn't, like, come into the equation, or it comes into the equation in another way. The idea is that like there's granular levels of how we want to describe a physics problem, right? And my point here is when the local measurement was made, when we figured out, oh, the orbit decreased by 30 minutes between the two of them, what we really did was figure out a local beta. We figured out a local momentum transfer that happened because of the moon and how much escaped the little moon's gravity, right? To create a nudge between the moon in relation to the big didymus. So dimorphis is now speeding up in relation to didimus.

Right. What we really care about when it comes to planetary defense is the sun binary system. What we care about is the heliocentric momentum enhancement factor, not the center of mass frame momentum enhancement factor. Here what we're looking at is from Earth, the impact on dynumous. Okay. Okay? And what you can see is you don't even resolve the binary system. It looks like a single dot.

Yes. But we didn't hit the main dot. We hit the moon. And yet there's all this ejecta that came out. Yes. All of that ejecta that came out has escaped the binary system. That ejecta not only escaped the moon, the main didymus, big asteroid couldn't even keep it together. Right.

So all of that ejecta escaped the moon. Yes. And the big asteroid. Yes. And has gone out into outer space. Yes. Which means that there is a momentum enhancement. factor on the entire system as a whole. It's a really nice, like, sort of little undergrad problem

on conservation of energy, right? Which is this idea that, like, even though I only hit the moon, I'm actually changing the trajectory of the entire moon planet or moon asteroid system. I didn't touch the asteroid. Yes. But the asteroid's orbit has been changed because I hit its moon. So, so as a maybe a pop culture reference point, let me know if this actually tracks with what you're saying. There's a famous, not a famous, there's a movie that came out maybe in the last two, three years called Moonfall. Okay. And the moon fell. Oh, dude.

Yeah, I know. I know this one. And so the point, even though the moon had yet to make contact with Earth, the simple fact that it moved from its existing orbital position around the Earth to being getting closer, totally disrupted a variety of things in Earth because the tides change. and the proximity. And so it's like a local move. It's like local, but it had this larger impact, even though it's maybe not the right analogy. Okay. So I want to take that a step further because in that one, what you're talking about is local changes again.

Oh, right? What I'm saying what I'm saying here is like suppose something hit the moon, which caused it to fall. Yes. Right. There would be an energy transfer into the moon. Yes. Right. So looking from Earth's perspective, the moon would gain some energy, let's say.

Now, looking from an alien perspective that looks at the Earth and Moon system as a single system, there would be a change in energy in that entire system. Both the Earth and the Moon would gain some energy. So both that system as a whole would change its trajectory around the sun. That's the idea. Depending on how granular you make your system, at the end of the day, conservation of energy and conservation of momentum are paramount. Yes. So if the momentum was transferred to the Moon, it'll also be transferred.

to the Earth-moon system. Yes. Which means that the Earth-moon system moving around the sun is going to change. That's what's happening here. That makes sense. That's the key that I need that I need everyone to try to

sort of internalize. Yes. Which is conservation of energy and momentum is true regardless of the size of your system. Yeah, right. At whatever level or layer you're observing the system, a change of momentum

in one of those layers will then will transcend across all of the downstream or upstream. I don't know which direction it is either. But I think one of those two. You get exactly what I'm saying, right?

And so if that ejecta is escaping the combined gravity of didymus and dimorphis, then it's going to change the trajectory of the entire system. I see now. Which means that I need to figure out a beta for the entire system.

Yes. Not just what I had figured out before, which is just the little moon. Right. around this. Yes. That makes sense. Because ultimately,

from a planetary defense perspective, that's what matters. You care about the whole system. Yeah, yeah. Yeah, that's what matters. And being able to change the whole system. The whole system. But in order to do so,

you need to understand the component parts necessary. Yeah. To be able to impart that level of change on the whole system. Exactly. Yeah. And to tell you just how hard that is to do. Right. The heliocentric velocity,

this is something that I covered a little bit earlier, The system moves at 23 kilometers per second, and I'm trying to detect a change that is less than 1 millimeter per second. This thing is moving at 26 kilometers per second, and I need... 23. Sorry, yeah, 23 kilometers per second. This thing is moving at 23 kilometers per second, and that velocity is going to change by a millimeter per second, actually less. Does that I accept that several orders of magnitude? A millimeter is a thousandth of a meter, which is a thousandth of a kilometer.

So this is about 10 millionth. One part in 10 million is what I'm trying to sense. Or an asteroid that is millions of miles away. We like to say this is non-trivial. This is extremely non-trivial, right? Yeah. Like to make that measurement, this is another lesson in, again, some of our favorite topics on the podcast, precision measurement.

Right. That's such a key. We have a toolbox in science with hammer, screwdriver. Some tools are more useful than others. Yeah. Some tools you use all the time. Like a hammer, there's a lot of things you can do with a hammer. Lasers is the thing. And physics.

You see, I put a laser out. Put a lady out. But I think, again, measurement, it's not, measurement is a whole craft in and of itself with a level of density of complexity and expertise necessary to be able to do so in a robust enough way. Yeah. And this is a measurement challenge.

Speaking of measurement challenges, in our first nine minutes of our appearance on the Dave Chang show, which is on Netflix, check it out. Oh, yeah. What's spent on the double slit experiment, which is a measurement problem. Yeah, that is a measurement problem. That completely caught me off guard.

Because we just got there and he was like, came in with a hard letting. What about the MIT paper? I'm like, that was like months ago. What is going on? I can't believe he like watched that one. Like that's, he's, he's an OG fan. And he's also quite, quite sharp.

Yeah, dude. He remembered so much. He's quite sharp on that. Yeah, that was really cool. But the measurement problem is the idea. Measurement problem. And this is where this particular paper comes in. It's measuring this unmeasurable one millimeter per second,

actually a lot less change. Change in a 23 kilometer per second object. That is millions of miles away. And this was a paper that came out in science advances, direct detection of an asteroid's heliocentric deflection. Okay? The target change that they measured was 11 microns per second. Jesus.

Okay? Out of 26 kilometers per second. Okay? And what this means to just give you a sense of scale. Yes. So that asteroid system goes around the earth every 770 days, so that's about two years. And this tiny change in velocity means that the, Two years of orbit has been shortened by 0.15 seconds.

Oh, my goodness. Okay? So a year on that asteroid is now shorter by 0.15 seconds because we crashed into the moon. That's incredible. And so there's sort of two things about this, which is interesting. One is what an exceptional job we've done to be able to measure such a small scale change. And that's what we're going to get into next. And then the second piece is now we then have a reference point to be able to say,

how much do we need to scale up the, because we just have a small little thing. We didn't send a big old, because also getting payloads into space is expensive and cost money. And we don't like to spend too much money now on fundamental science stuff. But now you could go to the joint chiefs and say, we're going to need a 100,000 megaton X in order to get the level of momentum change. But we just have a baseline now. Yeah, we have the numbers now. Right. Right. So in order to make that detection, right? So 11 microns per second is the difference between before and after, before the explosion, before the impact and after the impact. Before the impact, it was going at about 26, 23 kilometers per second. Right. And after the impact, it's still going at 23 kilometers. This is like in the hypersonic velocity or like air. No, this is not even hypersone. This is not even way. Way. Way. Okay. Way. Yeah. Like the speed of sound is 343 meters. per second.

Okay. So 0.3 meters per second. Okay. Okay. This thing is 23. So that's what? Three times, 60 times about 60 times the speed of sound. Okay.

Hypersonic is five. Yeah. So we're in UAP land right now. Yeah. Yeah. We're most likely in UAP land. Here's the idea, right? In order to measure that change of 11 microns per second,

what I need to do is have that precision on the before and after. Before we get into the after, right? Like, if I were to say, if I were to measure something like, oh, the speed of the car, like, imagine I'm a cop on the, on the highway. And the guy is going at 70 kilometers per second. And then I say, oh, he decreased his, he decreased his speed by 0.003 kilometers per second. Well, I'd need to know what the initial thing was, right? Otherwise, like, how do you, I could just be going like 71. If you said 70, that's only one significant figure for those students in science.

That means it could be 71 or 69 or 68, right? So we need to know the before and after equally well in order to make that subtraction. That's a really good point. We don't have like the tools in physics where I can like do destructive interference where I don't actually need to know the answer because the answer cancels out. No, we're not doing any fancy. We just need to know what the number is and then do subtraction. So the point being we need to measure it before this. We need to measure before we do anything.

Yeah. And then that measurement needs to be very, very good. Very, very precise, down to the micrometer level, right? And the way they did that was, so this system, Dyrmus and Dymorphus, has approached Earth over the past 29 years. And we have massive radio telescopes that have bounced microwave signals off this thing. And we can now fit the orbit with a simulator, like a small body simulator and JPL's Comet and Asteroid Orbit Determination Program. And from that, we can figure out what was the before velocity. Because we have this historical data that has captured pictures over time. Yeah, over 29 years.

So you're capturing the movement, even though the picture is static. Exactly. And it's not just pictures, it's also radar. Okay, right? Because we can beam it and it'll come back. So it'll give us a distance at least from Earth. Yes. And then the beam will also get blue shifted.

Yes. Because the guy's either coming away from us or, like, if it's, If it's moving away, then it'll be redshifted. If it's moving towards us, the beam that bounces back will be blue shifted. And we can measure that difference in frequency to figure out the velocity. You do this over multiple years, 29 years, and you get a really nice number. And that's the before. And this is like we basically have a, it's like when you go on a run on an app, like whatever, Strava or whatever,

and you get the little trail and it shows like where you've run before. It's like we have that very precise. of the movement of this over time. Over 29 years. It's been doing the same thing, right? Over and over again. Okay. So now, how do we get after?

Because it's only been three years. We've only got three years, not 29, in order to gather this data. So there's two ways to do it. One is through radio astronomy, astrometry, which is the same thing that I was saying earlier. So radio astrometry is simply you use radar to bounce a microwave signal there and back. They actually use the Goldstone Solar System radar, which is part of J-Based. APL's deep space network. This is actually whenever we go to Mammoth.

You know, next time when we go, we should like just pull over. And I don't think we can get in because it's like security or whatever. Hey, let us in. It's still like next time we go, I'll point out the radio dishes to you. So we use that. And from that, we can get the time delay. So that'll tell us within tens of meters what the position is. We get multiple positions.

Then we can calculate the momentum. And also the fact that the signal is ready. shifted or blue shifted, that Doppler shift is going to give us some idea about velocity. But over three years, it's not going to give us enough of that error bar going down. It's going to be part of it, but we need something else. And this is where something very cool comes in. It's called stellar occultations. Okay?

The idea is the asteroid is going to pass in front of stars in the night sky. No way. And it's going to eclipse stars. No way. And so we can measure whenever it eclipses stars, the star is going to blink. And we know the star doesn't actually blink, right? The star has a constant brightness. So when it like goes down and up, and we know where it's going to be.

So we're like, dude, this thing is going to move in front of that star. Yeah. Like around this time. Yeah. So we can have volunteer astronomers. And that's what I found very cool about the story. There were volunteer astronomers that went out. Yes.

And tried to capture these stellar occultations. We're effectively trying to capture the shadow of this asteroid passing in front of a Star and the night sky. And then the star. Yeah. The shadow is only about a kilometer wide. Oh my God. Okay.

So you need very precise, like, timing of, like, where you need to be in order to capture it. And also space. And one thing that I found really cool was there was a guy, volunteer again. He observed two of these occultations. He drove two days each way in the Australian outback. To get it. In order to get this data. That's, we, that's.

Like, shout out to this kangaroo. Jack guy, dude. The Ozzy, Ozzy, Ozzy, Ozzy. Yeah, it's pretty awesome. But this is so interesting, again, because sometimes, you know, there's a lot of astro photographers, I guess, that are very popular now on socials and stuff like that. And it's a real craft in and of itself. Yeah, yeah, yeah.

This guy had to know where to point, like how to get the data, exactly, exactly where to be. Because you've got a one kilometer radius that you need to get this thing. And you can not only do it for the joys of being curious about the universe around us, but also be a participant and a contributor into sort of institutional research. I think he should put planetary defense. Yeah, a researcher on a CV, right? Whatever he's doing in the Australian Outback, that should be part of a CV. So with this international network, they captured 22 distinct occultations between October 2020 and March 2025.

Okay. And that is where they got all of their data to where they can say 11 micrometers per second is the change in the velocity of this asteroid. Because now we have like another reference point, another reference frame by which to like understand because we have the historical data set from the 29 years. Yeah, and that's the before and we need it after. And we need an after. And so basically the the stars that are behind in between, the stars that are behind this passing

in between us create a reference point for us to make. measure against. Yes. And that allows us to get the after because we have such a precise understanding of the stars and their positions. And their positions. So it's almost like they're a ruler. Yeah.

The stars become a ruler by which we're measuring. And it's extremely precise. And that's how you get that precision in such a short time. Yeah. If we just waited for Goldstone radar to keep going, we'd have to wait for it to come back. And then like, you know, that's just going to take forever. That makes so much sense. But if we supplement that with this really tight astronomical data, right?

And then we run the models on it. Then we can get the error rate down to where we can really say, yep, 11 micrometers per second is how much we took away from that asteroid, which means that it's year, which is about two years, is going to be shorter by 0.15 seconds. And that's how we get that data. That's so fascinating. That's how we conclude that number. Right. But it's hard work. And it's a really creative solution to the time problem.

Because it's like, you know, what is it? A necessity breeds invention. and they're like, okay, you don't got time. Yeah. What are we going to do? Yeah. Well, what if? Yeah.

And it worked. Very good. Very good. And so now from there we can actually calculate the momentum enhancement along the heliocentric path, not just the local path. Yes. But how much boost did both of them get on their way around the sun? Yeah. Given that my, you know, Kamikaze drone satellite had a certain momentum, how much momentum boosted they get?

And the beta that we get is about two, a little bit more. more than two. So twice as much momentum was transferred to that system than what we put in because of all the ejected that came out. So basically the amount of momentum we put in, that same amount was ejected out. Mm-hmm. Yeah, yeah. I thought it was pretty cool.

That's very nice. It also confirms like the density of this moonlit. Yeah, it's about significantly lower than solid silicate rock, which means that it's like highly porous. It's actually not like just like normal rock. It's like a very light rock. It's like the rock you are supposed to wash your feet with, what do they call it?

Pummois stone. Yeah, yeah, pumice stone. Exactly. Yeah, yeah. It's 1630 kilograms per meter cubed. Okay. Which is, so it's still gonna, um, it's still gonna sink in water. Water is a thousand kilograms per meter cubed. I just want to, you know, it's not that much more dense than water. I just want to note we, uh, just implemented a latex notation in our script notes. Yeah, it's pretty great. Uh, which look at that plus or minus sign. It displays a real formula. Yeah. And I'm looking at this and you just riff that off the cuff so quick. Relax and let Ralph's delivery handle your grocery shopping this week. We start with only the freshest items, then review your list and carefully choose each one.

Then we pack it all up and deliver it in as little as 30 minutes, so you can feel confident it's what you ordered. Fresh groceries, your way, with Ralph's delivery and pickup. And right now, you can save $20 on your first delivery or pickup order. Ralph's, fresh for everyone. Ambition comes in all shapes and sizes. At First Citizens Bank, we roll with your goals because we're built for what you're building. Fit for your ambition for Citizens Bank. Yeah, because I can actually read it.

Also, the beta with the under, like there's a subscript, you know, Beta H along, because that's the beta heliospheric along the path. Before I had to like read the latex where it would go slash BETT. T-A underscore squiggly parentheses H. Oh my God. Now it's an English. Yeah. Now it's an actual English. Very good. So broader implications.

Yes. We've got a valid measurement of beta. Yes. Now that validates this kinetic impactor. That means that like in the future we're not blowing things up. Right. Like if we're going to get twice the momentum enhancement. Yeah. That means like, you know, all we need to really toggle is how big is the payload. Yep.

Which we can. We can toggle as much as we want. Right. We can do multiple hits if we need to. And then, like, how fast are we moving? How big is the payload? How fast are we moving? And then multiple if we need it. Right. Right.

So this is now like a strategic advantage for us. It confirms that we can actually do this. All the things we've seen in all these asteroid movies, some of which they just tried to put a drill. I think Armageddon, they tried to drill and then blow it up. Yeah. But then it just created thousands of pieces that still came into the earth. We're not doing that.

We're not doing that. less, okay, it's less Hollywood-esque. There's no big nuclear explosions in space, but I just want to live. Right, right. And we just need to nudge it. We just need to hit it. Yeah, side swipe it a little bit. Yeah, yeah, exactly. To go in the other direction. Yeah, it's like a hockey puck, right?

Just like, you know, you just move it out of the way. The Near Earth Orbiter Surveyor. Yes. So this thing is NASA's next generation space-based infrared telescope. It's going to launch in 2027 in September. And it's designed to detect dark asteroids that are not visible by ground-based optical telescopes. For whatever reason, sometimes they're coming right at us from the sun. They're like in our orbit, things like that.

So that's what this surveyor is going to do. That's going to give us more and more, you know, just in case some random crap happens. I want to note that the 2013 Russia example that we talked about because some of the question might be like, oh, well, planetary defense. We already know where all this stuff is, so we'll be fine anyway. That 2013 one came out of nowhere. It came out of nowhere and no one saw it. Yeah.

And it was super alarming because I was like, I thought you guys. had this together. Right. And so planetary defense is not, we are a single point of failure. Yeah. Like, like, species. I think, I think we have, I think NASA says that we've got all of the, um,

all of the like, really bad ones, like the dinosaur impact type ones, probably under control, but still like, like, the one, the one on Russia, right? If, if that had not exploded out in, right, 10, you know, whatever

the altitude, like, that could have been really bad. That could have been really bad. That could have taken out a small city. Yeah. I don't want that either. Right. Right. Because the other flip side of this, which is just sort of an interesting dynamic in the world we live in today, which is relevant, is I think this is actually the

this is the plot to Paradise, the Hulu show. Yeah. Where it was an external object that was coming in, like a comet or an asteroid. And it triggered nuclear war because of its like as extensional context. So like if something has impact

and then there's misinformation like there's not good information sharing about what the thingy. Yeah. I mean we're going to war for a lot less. You know? So it just creates, you know, planetary defense is really important.

Yeah. We, you know, we are not well equipped to survive a massive impact. No. So I'd rather not have it. And we now have at least a baseline to be able to provide the defense

industry, the answer when they all get around that round table and they have an extinction level event from a celestial or cosmic object had its earth, the NASA scientists have the math now. Exactly, yeah. And one last thing that I want to highlight is that this is an international effort, right? Planetary

Defense, we're on the same planet. The ESA has Hira, which is arriving at didymus and dimorphis. It's actually going to map out the DART Impact Crater. And it's going to directly measure dimorphis' mass via radio tracking and really refined those values of delta v and then beta subsequently and so on and so

forth. So it's really international effort that we've just sort of created a lab test bed in space of Didius and Dymorphus, this binary asteroid system. It's very cool. Look, any space story you know I'm in on. I owned both Armageddon and Deep Impact on VHS when they both came out and whatever it was in 1997. I still think it's hilarious to think that Bruce Willis and Ben Affleck, who were a bunch of guys who worked on an oil rig, were the only people who could save Earth and had to learn how to become astronauts. And apparently it was easier to train people who worked in an oil rig to be astronauts than it was to change. Astronauts how to drill on this thing.

Ben Affleck did it. If you, one of the, you're a movie buff, I think in the extra scenes, whatever, the, when we used to have the DVDs with the extra stuff. the director, like the director's cut where they would voice over while it was playing. He was just taking the piss about how ridiculous the plot was to the movie. That makes sense. Very, very cool story. Dart, our planetary defense story today.

And the key piece to this was the ability to calculate the heliocentric momentum change. It's really, it's really a precision physics and precision astronomy story more than anything else. Right, you know? Right. But the media, it's, it's really a precision physics and precision astronomy story more than anything else. Right. like to say planetary defense. Yeah, yeah.

What is the, how do we make this militarized? Yeah. But I just, I just love that like, you know, for astronomers, like, this kind of precision is like unprecedented, right? They're like plus or minus 10,000 kilometers, you know, type of guys. Right. Right. Right.

And just to recap, this was in science advances. Came out March 5th, March 6th. University of Illinois, Urbana, Champagne, which has been a key. institution we've talked about quite a bit on the pod. Also Nash's JPL, Johns Hopkins Applied Physics Lab, and a few European universities in collaboration, as you were just mentioning, from the ESA side. Really fantastic story. We're going to wrap up on the episode for the day. However, we have one, we have two things. One, we need our comment, which we did not write out in our script notes. Oh, no, why do you? No, we do. No, we do.

It was, why do you think the Russians have so many dash cans? Oh, yes, yes. So if you're still listening, an hour in, because we are now not doing two and a half hour episodes, we're doing multiple, more bite-sized, more digestible episodes that are focused. So, why do you think they have so many dash cams? And we do want to do one correction from episode 29, which was from the rundown related to the research study about the Neanderthal human mating. bias. We really appreciate all of the comments from folks on a variety of platforms on that story.

Part of the challenge is with the rundown. It is not a main focus. So we don't necessarily get into the weeds as much. We use some imprecise language in that segment. And the study itself was really just focused on mating bias. There was a conversation about the difference between consensual and non-consensual that was not in the purview of the study itself. And so we appreciate that feedback. We will keep that in mind in terms of making sure we are much more attuned and accurate as we cover things, even if it's in the rundown and not a main story. So we really appreciate that feedback from you guys. I am your host. Lester Nare, joined as always by my co-host and our resident PhD, who is not a planetary defense researcher. No, just a measly grad student.

We'll catch you guys for the next episode this week. Yamava Resort and Casino at San Manuel is California's number one entertainment destination for today's superstars. Catch the Jonas Brothers return to the Yamava Theater stage on April 30th, the powerful vocals of Demi Lovato on May 17th, and the signature Southern Country Rock of Eric Church on July 19th. Tickets on sale now at Yamavat Theater.com, only at Yamava Resort and Casino, celebrating its 40th anniversary. You in? Must be 21 to enter.

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