This NASA team’s work means the whole world can sleep a little better

Tom Temin Okay. You launched a rocket that crashed into an asteroid. And I guess my first question is, was this rocket able to slightly change the trajectory of that asteroid? I want to understand what the mathematical calculus was. I mean, how did you discover this in general? Because an asteroid is very big. A rocket is very small. You could launch something as big as an asteroid. That is not possible. But if you shot a marble at it, it wouldn’t make any difference. What was the process of figuring out how to do this? Scott.

Scott Bellamy, I think the easiest way to start answering that question is to realize that it’s not just Brian and me. We have a whole team behind us. Here we are in a management position. But you know, this whole effort is supported by a large group of scientists and engineers who work at the Applied Physics Laboratory to help answer this.

Tom Temin But tell us what the team did.

Scott Bellamy So if you look at it like you’re playing billiards in space, you’re playing pool, galactic pool. So this is no different from how you described this scenario, where the smaller spacecraft hits the larger asteroid. But if you take the smaller spacecraft and look at how fast it’s flying, and what its mass is in relation to the object it’s hitting, then you determine how much kinetic energy needs to be transferred from one body to another to produce a change in space. his job. And so the scientists who worked on the design of the mission came up with the parameters that needed to be adjusted to achieve the result of changing the orbit of the Dimorphos.

Tom Temin Okay. And what happened when you launched it? It hit the asteroid.

Scott Bellamy Definitely. That’s actually the point of highest tension in this whole event: what happens when the asteroid is hit? It hit the asteroid. It’s, you know, a very high speed. And with the smaller asteroid Dimorphos, we got a lot of spacecraft confetti. We had a spacecraft with a mass of just over 1200 pounds, you know, a little bigger than, you know, your typical refrigerator. And he reached, you know, over 13,000, almost 21,500 miles per hour. So, you know, it wasn’t just a glancing blow. It was a very precisely targeted impact on a specific spot on the surface of Dimorphos to achieve that perfect little amount of English on the spacecraft’s trajectory and to, you know, sink that all into the core bag exactly the way they planned it.

Tom Temin’s Speed ​​is a big factor here, almost like a hypersonic missile. It is the impact of the waiting times and the speed that form the force. It doesn’t even have to contain an explosive.

Scott Bellamy That is the energy mass times the speed. You calculate the kinetic energy of the impact. And so with a known kinetic energy hitting an object moving at a certain speed in its orbit, you take the speed and split it into whatever you’re standing directly opposite. And then you know approximately what the mass is coming at you and you’ve made the spacecraft big enough to hopefully exceed what it takes to change it, because you could get hit by a Volkswagen on the highway. And if you drive a huge SUV, it will still affect your trajectory on the road.

Tom Temin Yes, it can turn you around if the angle is right, I think.

Scott Bellamy Yes that is true.

Tom Temin And Brian, you’re the program manager. How did you convince NASA? And I think ultimately Congress, I mean, sounds like a little bit of science fiction. You know, you’ve seen cartoons of rockets landing in the eyeball of the moon, this kind of thing. How did you convince them that this was a worthwhile experiment?

Brian Key It didn’t take much convincing. These ideas have been around for a while. The Science Mission Directorate headquarters established a planetary defense office within the Planetary Science Office. And it was the planetary defense agency that actually put forward the idea. Once they selected the mission, we took over leadership of it. So it was the Planetary Defense Office that brought it out and said, Yes, this is a good thing for us to try. And they went to APL and got a proposal of what was needed. They then handed it over to us to implement.

Tom Temin Was the rocket itself just a rocket with the weight of itself? Was there. Were there lead weights on the front or anything to get it to the right mass you thought was needed?

Scott Bellamy Let’s think about it this way first. It’s not the whole rocket. It’s just the spacecraft launching the rocket. So now everything about the spacecraft, the essentials to be able to fly it, you need to be able to have the items that control the trajectory of the spacecraft, aim the solar panels, the solar panels themselves, the optical instrument that needs to be there to do the targeting. So the spacecraft itself was literally what it needed to fit into the launch vehicle. The other fairing at the top has the housing and has enough mass to effect change. Now the weights are sometimes added to each spacecraft to get the balance where you want it. But no, it wasn’t like a race car that has to carry 1,500 pounds of extra weight just to get the mass where they want it. In this case, in most cases, if you still have room to play with, you prefer to put something useful in it to complete the mission. But different than just dead weight.

Tom Temin And it’s been, you know, a few centuries, I think, since an asteroid hit the Earth, 60, 65 million years, maybe a long time. Does NASA typically look at asteroids? And what is anyone’s best guess about the chances of being hit soon by another asteroid big enough to harm humanity? I think we get hit by small meteorites all the time.

Brian Key The last asteroid to hit was not 65 million years ago. More recently, fairly large asteroids have hit Earth. Just not in the United States. I think the last one was over in Russia. We have a sister mission that’s currently in development that will actually put a camera into orbit that will actually monitor the sky and collect data to determine where these asteroids are, what their trajectories are, or whether are they a danger to the Earth or not. I think that particular mission is scheduled for launch in 2027. It’s called Neo Surveyor.

Tom Temin Certainly. And a few final questions. The asteroid you created, is a proof of concept that you could change. What was its mass? And then what is the largest mass that you think could actually be affected by a launch?

Scott Bellamy So the Didymos system is the target for this test. Didymos is a binary asteroid. It has the larger primary and the smaller secondary moonlight that was targeted. This gave us the opportunity to actually observe the change we were hoping for. So the smaller asteroid is called Dimorphos. it has an average diameter of 160 meters. And we don’t necessarily have a good mass estimate for either the primary or the secondary. I can get something out of it to share with you, but it’s still just an estimate. The biggest factor here was that it is in a stable orbit around its parent. It is typically measured at an average plus or minus a few seconds of 11.9 hours. And we know how big it is. So we can estimate its mass and use that information compared to the orbital dynamics between the two to understand how big the change might be. Usually, I mean, you asked how heavy one of these is. We usually talk about them in terms of how big they are in average diameter. Yeah, there’s some interesting data out there, you know, about asteroids that are about four meters long and there could be 500 million of them that have, you know, teasers in their orbits, the ones that are about 25 meters long, you know you, 5 million. But then you get to the dinosaur killers, who are about 30,000 feet away, and they think these are just four of the ones hanging out there in space. These are the ones we need to worry about. They have orbits that periodically cross Earth’s orbit, or they can pose a potential danger to Earth-crossing. Now there are a large number of asteroids in the two belts, those between Earth and Mars and those beyond Pluto. There’s just, you know, LA 405 at five o’clock in rush hour, which looks something like this.

Tom Temin But you could change the trajectory of something that was 160 meters wide. Can you change the trajectory of something 10,000 meters in diameter?

Scott Bellamy My answer is yes. The answer depends: what’s more important in this scenario is when you find it, how big it is, and how quickly it will get here. So if you catch it early enough, you’ll have time to put the mission together, get it built, and launch it to travel there. If it’s too late, you’ll already be behind on catching up to get the most benefit from a mission like Dart. Do you want to find the asteroid when it is as far away as possible? Certainly. And that you can get there as quickly as possible. The further away the asteroid is, the smaller the change in its trajectory you need to make because a half-degree change in its trajectory over five years will result in a very large missed distance once it finally reaches Earth.

Tom Temin Is there a danger of it being accidentally hit, so it’s more likely to hit the Earth?

Scott Bellamy That’s a hard question to answer, and I don’t even know if I want to try.