Transcript
Julie Kiefer: Welcome to U Rising. I'm Julie Kiefer, associate director of science communications at University of Utah Health and host of this episode of U Rising.
Utah has a lot of wide-open spaces that are ideal for stargazing and if you have a telescope or star app, it's easy to figure out what you're looking at. But these tools may have helped you spot something else in the night sky: junk. Space junk. Dead satellites and rockets and lots of them.
My guest today is Jake Abbott, a professor of mechanical engineering, and we're going to talk about space junk—what it is, how it got there and his idea for how to clean it up. Welcome to U Rising, Jake!
Jake Abbott: Thanks, thanks for having me.
Julie Kiefer: Jake, apparently the old saying of, ‘What goes up must come down’ isn't true when it comes to space junk. So, what's happening up there and how much debris is circling the planet?
Jake Abbott: Yeah, it's funny. I think the saying, ‘What goes up must come down’ is actually true. What the problem is, is what goes up doesn't come down and we have to figure out how to get it down.
Jake Abbott is a professor of mechanical engineering at the University of Utah.
Julie Kiefer: And why is that?
Jake Abbott: Well, if you're up in space, you have a fixed amount of energy if you're an object and so your orbit is really stable. It might be a circular orbit or it might be an ellipse, but it doesn't really change over time and it's because there's nothing putting energy into you or taking energy out of you when you're up in space.
What we need to do is we need to figure out a way to take energy out of these objects and when you take energy out of them, they slow down and their orbit goes into a lower altitude. And as you get into a lower altitude, you start entering where the atmosphere, which is super thin up there, gets a little thicker, and then you start to experience a little drag like you would if you were in your car driving down the freeway. You're very aware of the wind drag on Earth, but up in space the atmosphere is so thin that it's very faint, but it's there, and then that takes a little energy out of you and then you slow down a little more and that makes your orbit drop a little lower.
Now the air gets a little thicker and the process kind of builds on itself and before you know it you're down in a point in the atmosphere where the air is thick enough that the drag is really meaningful and the object is going so fast that now it starts getting really hot and eventually just sort of spirals into space quite rapidly and burns up.
Julie Kiefer: And burns up and then we don't need to worry about it falling on us.
Jake Abbott: That's the hope. Yeah, there's a lot of debris circling the planet, some people . . . do you have any guess of how much there is? You think you have any intuition for it?
Julie Kiefer: How do you even measure it? In times?
Jake Abbott: I know. How do you even measure it?
Julie Kiefer: Yeah.
Jake Abbott: Yeah. So, in objects there's estimates that there's something like 130 million objects, which is like a number you can't wrap your head around really. But that's including really tiny, little things, little things that are less than a centimeter in size, really far away.
If we think about bigger objects, the kind of things we mostly think about, there's about 7,000 active satellites in our orbit that are currently working. And then there's another something like 30,000, I think, objects that are being tracked by United States government military.
It almost looks like air traffic control where you're tracking these objects as they fly around to keep track of known objects. And these are all objects that are sort of like 10 centimeters and bigger. So, you should picture 10 centimeters is maybe like a baseball, so that size and bigger, and those are things that are in low Earth orbit. And then in geosynchronous orbit, which is actually way farther away from Earth, we can only track things that are a meter and bigger. So now you're talking about quite big things, the size of like a human body and bigger.
Julie Kiefer: So, things, I mean, are these debris, are they actual, could there be spy satellites? I mean, just different things that maybe we don't exactly know what they are?
Jake Abbott: It’s a whole host of things. So, this term ‘debris’ typically gets, everything gets lumped into it. That means stuff that isn't serving a purpose. So, it's satellites that used to work but don't work anymore. It's parts of rocket bodies that were thrown off, stages that are just floating around now, just big, huge cylinders of metal. And it's things that have already had the types of accidents that we're trying to avoid where something has crashed into it and it has shattered and blown into a ton of pieces that all flew in different directions.
And so it's all of these things all together and, depending on what the object is, the kind of interest on how to solve it is different. So, if you have a satellite that's defunct, maybe the solution is to somehow make it have a useful life again. So, it's not a salvage operation as much as a repair operation. Where some objects were never intended to have any use, they're just up there as junk and they have the potential to become lots of junk and so those are high-priority objects that you want to somehow figure out how to get out of orbit and get out of orbit means burn up in the atmosphere basically.
Julie Kiefer: So, do we have to worry about this junk? I mean, are they in a fixed orbit where they're kind of keeping away from each other and other things? Or could there be crashes and these things come tumbling down and we have to cover our heads to watch out?
Jake Abbott: The tumbling down isn’t, I think, so much of a problem. Most things are small enough that they would burn up before they hit Earth, and most of the Earth is ocean, and then a rest of the Earth that isn’t an ocean doesn't have people in it. So the chances of you getting hit on the head by something is very low, but there is a real worry that they will crash into each other.
And not that long ago, the International Space Station actually had to do an evasive maneuver and they changed their altitude because they saw a piece of debris that was coming that they knew was just going to be a little too close for comfort. And so they changed their altitude and that takes energy. It takes fuel to change your altitude if you're the Space Station.
Julie Kiefer: Watch out.
Jake Abbott: And it's like a bullet.
Julie Kiefer: Yeah, right, so, it could do real damage, something like that.
Jake Abbott: Yeah, poke a hole in something that's a sealed environment.
Julie Kiefer: And does that happen very often or that was a rare thing?
Jake Abbott: That's a rare thing, but the problem with the way we put things into space at this really rapid rate is that the chances of these sort of things happening is going up and up in an exponential way. And there's a famous thing known as the Kessler Syndrome. This scientist named Kessler, he describes a process, decades ago, in which you will eventually get to the point where there's enough objects that the probability that there will be collisions goes up to the point where it almost becomes a chain reaction that you can't stop.
Julie Kiefer: Okay, so that's a big problem. So, we talked about the possibility of collisions and space debris causing collisions. Are they causing other troubles, too?
Jake Abbott: Well, I have heard indirectly that some of these satellites that are being put up into space are causing problems for telescopes, basically creating light pollution for telescopes. So, if you imagine seeing these Starlink satellites flying overhead, you can see them. They're a bright little light and, in fact, they're like one of the brightest stars in the sky. And so if you're a telescope that's trying to look out into the darkness of space and see very faint things, all of these new satellites are some form of light pollution for you.
Julie Kiefer: I was in Capitol Reef camping this summer and it's a dark sky area, designated dark sky area, so I was looking forward to seeing constellations in the Milky Way. And the first thing I see at night is Starlink, this chain of satellites put up there by Elon Musk. And it's like, well, that's not really what I came here to see.
But it seems like that's the start of something that's probably going to keep happening a lot more frequently. Is that something we need to be concerned about?
Jake Abbott: Well, I think so. I mean, I don't know the exact numbers, but I know that a significant percentage of all of the satellites that are in space, active satellites, are Elon Musk satellites.
Julie Kiefer: Oh, interesting.
Jake Abbott: Yeah, and it is very interesting. I mean, not that many years ago I would sit out and look at the sky and you'd see the Space Station go around and you'd notice it because it was like the one star that was moving.
And you could watch it, and if you stayed out all night, you can maybe see it pass you a couple of times, right, a few times. But now, yeah, Starlink, it looks like there's a highway, right, one behind the other, behind the other. And with each of these new additions, there's just more chance something like this can happen.
Fortunately, the community has decided that anything that's being put into space now has to have a plan to de-orbit itself within five years of end of life. And sometimes that just means operating at such a low altitude that there actually is still a little atmosphere, and that atmosphere will slow you down. And if you stop sort of fighting against it, the atmosphere will naturally slow the satellite down and burn it up on its own.
Julie Kiefer: So there is kind of a regulatory body that's starting to look at these things.
Jake Abbott: Yeah, and make it be sort of a priority that you can’t ignore.
Julie Kiefer: So, in the meantime, your work directly has to do with this issue. And you published a paper describing an idea and a technology that could be used to clean up this debris. So, tell us about that idea, the Omnimagnet?
Jake Abbott: So the Omnimagnet is actually an invention that came from my lab a decade ago, and what an Omnimagnet is, is it's an electromagnetic cube that can make a magnetic field that's pointing in any direction. It makes a dipole field.
So, if you were to hold a little magnet in your hand, the kind of magnet you imagine with a north pole and a south pole, the field it makes is a dipole field. The field of the Earth is actually a dipole field also. So, you can picture that magnetic field that such a magnet makes. An Omnimagnet is a cube that's really three sets of wires and a core but what we can do is we can make a field that looks like a dipole field, but we can point it in any direction and we can rotate it rapidly without any moving parts.
And when we first invented that, I was mostly interested in uses in medical robotics because most of my career I've been focused on using magnetic fields to manipulate medical devices. So, these would be things that are inside of your body like capsules moving through your intestines or micro robots that are drilling through your brain tissue. I'm still working on those things.
But we came to know about this problem of space debris and I was interested, I've always been interested in the idea of can you use magnetic fields to manipulate things that people don't think of as magnetic. So it's pretty easy to manipulate a magnet. So, the things, when we talk about these medical robots, we're literally putting a magnet, a permanent magnet, inside the human body in some way in a capsule on the end of a catheter. But this stuff in space isn't what you'd consider magnetic. It's mostly all aluminum. And if you right now come upon an aluminum object and try and stick a magnet to it, it won't stick to it. It seems like it's not affected by the magnet.
But it turns out, and this is something people have known for a long time, if you expose any conductive metal, including aluminum, to a time-varying magnetic field, in that moment while the field is changing, the aluminum will experience forces and torques on it, but only while the field is changing. So, our idea was basically if we always keep the field changing in some way, and we do that by rotation, if the field is always changing, then we can always be inducing forces and torques on these metals.
And the first thing we did is we said, okay, are these meaningful forces? They're very small compared to the kinds of magnetic forces we're used to. But it turns out, yes, when I expose a piece of metal like aluminum to a rotating magnetic dipole field, it will experience forces and torques. And we modeled that very well. And then we sort of invert that model and we say, okay, now we have an object and it's surrounded by these field sources, and I want to generate some specific force and torque on that object. What combinations of things do I need to do from my different magnetic field sources to, on average, make the force and torque that I want? And then we solved that problem and we demonstrated that we can actually manipulate non-magnetic objects in our lab using magnetic fields.
Julie Kiefer: Interesting. So, the idea is that you would be changing the direction of the space debris if we're putting the application in there, that context.
Jake Abbott: So, the killer app for us, the thing that everyone was really excited about, is a problem that no one seemed to be able to solve. And it's this problem of what’s called de-tumbling. So, when you come upon an object in space, it has over time, this piece of debris, it has started rotating, and it probably started rotating slowly at first, but then it rotates faster and faster. So now as you come upon this object, it’s woof, woof, woof, woof, rotating and there's no safe way to reach out and grab it.
When you think of these objects, you need to picture fragile objects. These are things that were designed to be light because the weight is hard to get up into space and they can have antenna sticking off of them and solar cells sticking off of them. And what you don't want to do when you grab the object is break it and create a bunch of space debris, which is the problem you're trying to avoid.
And so there's different ideas that people have proposed largely from the robotics community, which I’m part. One idea is that you kind of would throw a net over these objects.
And another idea is, it almost, the way I think of it, is how you would sort try and break a wild horse. You basically just jump on it and ride it until you get it to settle down.
And so the notion is if you can somehow figure out how to grab onto this tumbling object and then just ride it, but you're a little spacecraft that has thrusters on it, then once you've grabbed onto it, you can bring it down to a controlled motion. But these are all really risky.
And so our idea is that you can basically approach this tumbling object and using our magnetic field sources, we can induce a torque that opposes the angular velocity of the object, and we just slowly slow it down. And these are small torques, so you have to picture long timescales that are very uncomfortable for humans to think about in normal robotic tasks.
So, you know, maybe it takes us a day to slow the object down. Maybe it takes us a month to slow the object down. But at some point we slow this object down while also keeping the object centered between our magnets. Without going to the details, as we try and de-tumble it, it will naturally try and get pushed away from us. So, we have to actively pull the object back in. And that's one of our papers that we've published recently is almost like a kind of real-life tractor beam concept where we can reach out with our magnets and pull the object between them. So, we have this conception where we will de-tumble the object, and then once the object isn't spinning anymore, then there's lots of traditional robotic approaches you can use. You can reach out and grab it with a hand basically.
Julie Kiefer: Okay. So, the main function is to stop this, well, stop it from tumbling and slow down the speed, I guess.
Jake Abbott: That’s our principle task. And the task that really no one else has been able to propose a viable solution for.
Julie Kiefer: So, Jake, tell me a little bit more about how this works. I'm trying to visualize it. Would there be a space mission for every piece of debris or does one craft go up there and take care of a lot of these things at one time? And tell me a little bit more about that process of how it brings it down.
Jake Abbott: Yeah, so you definitely wouldn't want to have a new craft for every piece of debris. The idea would be that you have these kind of maintenance, robotic maintenance craft that live in space and this is their job, going from one piece of debris to the next.
And you would probably target high importance targets. So, these would be big things that if they ever got crashed into would create lots and lots of debris so you'd want to bring down the big things first. You wouldn't want to be chasing down individual flecks of paint in space.
So, the idea would be you'd approach an object and you’d de-tumble the object. And once you de-tumble it, depending on what the type of object is, you do something different. So, for example, maybe it's a satellite that you just want to repair and repair could even be as simple as add more fuel. Like some of these satellites, they use consumable fuels where once you expel all of the gas you have, you don't have any jet thrusters anymore, so you just need to add more fuel to these things.
So then you'd repair those objects. And then once they're repaired, they're now not space debris anymore. Other objects, you are ultimately trying to de-orbit them. And by one means or another, what that basically means is slow them down, you slow them down, and then they spiral into Earth's atmosphere.
And different people have different approaches of how you might slow things down. Like, for example, one idea is you attach what's called an electrodynamic tether, and you should sort of imagine a long rope, I mean really long, like a kilometer long, that just sort of hangs down and goes down into Earth's atmosphere. And this rope is electrically conductive, so as it flies through Earth's atmosphere, it's also flying through Earth's magnetic field. And you're basically figuring out how to transduce that physics into a force that will slow you down. But, I mean, if you want to think of something in a very simple way, you could just literally imagine attaching some sort of rocket thruster to the debris that fires backward just to slow it down. And as the object slows down, it will naturally spiral into Earth.
Julie Kiefer: Okay. Interesting. So yeah, I mean it's interesting to think about, I mean, things have been shot up into space since 1965, so that's 60 years and there's that much accumulation of stuff. And only now are we coming up with technologies to actually be able to deal with that.
Jake Abbott: Yeah, it is interesting, and at least people have understood it's a priority now. Like, I have funding that's coming from the Space Force to work on this. That was specifically a specific call for universities to partner with companies to work on this problem of space debris, so people know it's a problem and there's resources being put into solving it.
Julie Kiefer: And so what are some of the companies and institutions that you're collaborating with to get this done? I think there was maybe a company that saw your paper and automatically thought of this application.
Jake Abbott: Yeah, so in just a complete coincidence that really has been great for me, we published this paper in the journal Nature showing that it's possible to manipulate non-magnetic things with magnetic fields. That was very exciting for me to publish that paper.
But then coincidentally, just a short time afterward, the Space Force announced this call for companies and universities to partner together to solve this problem of space debris. And so immediately a lot of companies reached out to me, actually, and I chose to work with this company, Rogue Space Systems in New Hampshire, on this problem.
Julie Kiefer: It sounds like there's still a lot that needs to be done. Talk about that a little bit. Where does it go from here?
Jake Abbott: Yeah, so I'm primarily interested in the basic science questions that I can answer in my lab and analytically. And then Rogue is actually designing the space mission and building the spacecraft that will implement these things that we're developing. And so that's currently where we're at. Rogue is actively designing spacecraft and space missions that will use this technology to go up and deal with objects.
Julie Kiefer: Is there a timeline for launch?
Jake Abbott: Well, I'm scared to speak of the timeline. I know they're very motivated to have something happen within just a couple of years.
Julie Kiefer: That would be amazing.
Jake Abbott: So it's proceeding quickly.
Julie Kiefer: Yeah, well, there's definitely a need for it. It's so fascinating to think about all this action that's happening around this we're not even aware of. But it's also to think about where this started. I mean, you started in the medical field thinking about this in applications for things that are being put in our bodies.
I'm wondering how you went from one to the other, but also is it working the other way around, too? Are you learning things from this experience that are going to inform your other work in the biomedical field?
Jake Abbott: Yeah, that's a good question. For sure the things I've learned from the biomedical field have helped me quickly realize these things for space. So far, there's no knowledge going the other way.
It turns out this ability to manipulate non-magnetic metals, it seems to me like space is the place for that to happen. And it's not very interesting on Earth, for me personally, although it is used already, this effect is used in recycling now. It's not dexterous the way we do it. We can really push on objects in very controlled directions and torque them to cause them to rotate in very controlled directions.
But in recycling, they basically flow trash over spinning magnets. And anything that's conductive metal will just get a little push and it can be enough that part of your trash falls into one bin as it comes off the conveyor belt and part of your trash gets this push and it jumps a little farther and jumps into a different bin. And this is how you can recycle metals from non-metals. So, these physics are used on Earth, but in this dexterous approach, robotic approach, space seems to be the place for that.
Julie Kiefer: Yeah, it's really fascinating. Well, we look forward to hearing how this goes. I'll be keeping a close eye on it for sure and we'll have you back to give us an update.
Jake Abbott: Thanks. Thanks for having me. This was a nice conversation.
Julie Kiefer: Well, thank you very much for being my guest on U Rising.
Listeners, that's it for today's episode of U Rising. Our executive producer is Brooke Adams and our technical producer is Robert Nelson.
I hope you'll tune in next time. I'm Julie Kiefer. Thanks for listening.