The Future of Space Junk

ANNA PLOSZAJSKI

You're floating through outer space, looking back down at the earth with wonder. And from the safety of your spacecraft, it's very peaceful. Maybe you see a satellite or two. Some space junk might float past. But really, it's just you, the stars, and the whole entire universe. I'm Anna Ploszajski and for this edition of Create the Future I'm going where no episode has gone before and tackling the issue of space debris.

HUGH LEWIS

Every single year since the beginning of the space age we have added more debris into the environment than we have functional satellites. Every single year.

ANNA PLOSZAJSKI

Countless bits of trash are cluttering up our orbit, and posing all kinds of risks to astronauts, space stations and even us back on Earth. We need some out of this world engineering solutions to clean things up and our guests today are leading that mission.

MIKE LINDSAY

We need to start thinking of maybe not burning up everything that we launch into space. We want to support a circular economy in space.

ANNA PLOSZAJSKI

I'll be chatting to Professor Hugh Lewis, a world renowned astronautics expert who's been studying this issue for decades. And Mike Lindsay from the sustainable space innovation company Astroscale, which is testing new ways to clean up outer space. Nice to meet you both. Very, very excited to hear more about this. Hugh, I'll come to you first, since you're first on my screen.

HUGH LEWIS

I'm Hugh Lewis. I'm a professor of astronautics at the University of Southampton here in the UK.

ANNA PLOSZAJSKI

And what does astronautics mean? How is that different from aeronautics?

HUGH LEWIS

I guess I deal with things that are in space, sometimes things that are traveling through the atmosphere to get to space. But generally speaking, I don't really touch the air stuff. A lot of my colleagues do, but yeah, I don't know anything about that.

ANNA PLOSZAJSKI

Got it. You're further away. Yes. And Mike, how about you?

MIKE LINDSAY

My name is Mike Lindsay. I'm the Chief Technology Officer for a company called Astroscale, which is dedicated to the safe and sustainable development of outer space for the benefit of future generations. And we are headquartered in Tokyo, which is where I reside.

ANNA PLOSZAJSKI

Wonderful. Thank you. Our topic today is space debris. And I'd really love to kick off by asking you to help us get our heads around this problem. How big is this problem? What's the scale? How much space junk, space debris is out there already?

HUGH LEWIS

So I think that there are a couple of perceptions. One is that space is big and that it doesn't really matter how much stuff we put into orbit. And then there's another perception that we make quite heavy use of very particular orbits. And then as a result we have some congestion, and it probably doesn't take too many objects, too many satellites and so on, to cause that congestion. So those two perceptions often kind of compete. What I would say from a quantitative point of view is that we're probably tracking around 30,000 objects that are bigger than a tennis ball and that there are estimates of about 1 million objects in orbit that are larger than a thumbnail. And all of those objects would be lethal were they to hit an operational satellite. When you get into those kind of numbers, we find that that tends to cause a lot of problems.

ANNA PLOSZAJSKI

Okay. Yeah, it's hard to imagine, isn't it? A million objects sounds like a lot, but as you say, the amount of volume, the amount of space that we're talking about is also a lot. Would it be possible to put it into terms that we'd be familiar with on Earth? For example, if I was walking down my road, if it's the same density as what's up there in space, how likely would it be that I crash into an object that's going to cause me harm?

HUGH LEWIS

If you're walking down your road, I don't know, maybe you're doing four or five miles an hour, you're not going to be seeing anything. The density is really quite low. Now, if you were to be traveling at the speed of an object in orbit, 17,500 miles an hour, you'd actually encounter probably quite a few objects and have a chance of colliding with them.

ANNA PLOSZAJSKI

Wow, so it is actually very high risk once you get into that scenario with those densities and those speeds.

HUGH LEWIS

Yes, yeah, absolutely. The challenge that you have on the ground, you know, maybe with your eyes, you could see something coming. For the objects in orbit, we rely on telescopes, on radar that are actually on the ground. So it's not just that we have a large number of objects. It's also that we're not quite sure what trajectory is there on.

ANNA PLOSZAJSKI

Got it. So it's as if you're walking down your road and you're very short-sighted or it's late at night. Yeah, exactly. You can't quite see what's coming.

HUGH LEWIS

And you haven't got your glasses on. Yeah, exactly.

ANNA PLOSZAJSKI

Yes. Got it. Got it.

MIKE LINDSAY

I was going to say, imagine that someone calls you on your mobile and says, you might want to know there's someone headed in your general direction. You might run into them in about 10 seconds, but you have no idea where that person is. So you have to rely on the voice on the other line telling you which way to go or where that person is going.

ANNA PLOSZAJSKI

Okay, thank you. That really helps me to kind of imagine the situation up there, basically. And Mike, you work for Astroscale. That's a company that's been set up to try and tackle this problem. Why is now the time to be tackling it? Has the situation got much worse?

MIKE LINDSAY

One could argue that the time to tackle this was many years ago, unfortunately we found ourselves in a situation where there are thousands of objects up there of considerable mass that will not be re-entering Earth's atmosphere as soon as we'd like them to. And what's more is that these larger objects have the possibility of becoming thousands or even hundreds of thousands of these very small objects that Hugh was talking about, let's say a bus-sized piece of debris that is multiple tons suddenly becomes hundreds of thousands of small objects that now spread across multiple altitudes and orbits. So Astroscale wants to help expedite the process of removing these objects. We're developing the technologies and currently proving a number of technologies as well that are needed to rendezvous with, safely approach, dock with and take custody of these objects, and then bring them out of orbit much faster so they don't pose a threat to anyone else.

ANNA PLOSZAJSKI

Understood. I really want to hear more about these solutions shortly, but first I want to give our listeners a picture of why these objects are here in the first place. You know, what is it that is causing the junk in the first place?

MIKE LINDSAY

The easiest answer is us. Everything we've been talking about is artificial. It could be the part of the rocket, the orbital stage of the rocket. It could be the satellite itself. It's reached the end of its life. It's been abandoned in orbit. Or it could be something as seemingly as trivial as flakes of paint that come away from a painted surface on a spacecraft or on the rocket stage. Fundamentally, it's all about the fact that we put everything onto rockets and we launch to orbit. We're not doing this without cause, without reason. Satellites are essential to our modern society. I think as per pretty much everything that humans have touched, we haven't done a very good job of doing it in a clean way or at an early stage, recognizing what we need to do to make it truly sustainable.

ANNA PLOSZAJSKI

And is that because we are designing these things to have an end of life or to perhaps without an idea of how they're going to be recycled or what's going to happen at the end of their life?

Yeah, think fundamentally once we get satellite into orbit, that's it. We don't really have any means to kind of get back in contact with it and refurbish it, maintain it. So it runs out of fuel or in the harsh environment, something goes wrong. So everything that we do, including all the regulations, set up this idea that we have disposable satellites.

ANNA PLOSZAJSKI

And Mike, is this problem getting worse?

MIKE LINDSAY

Well, I think that's an interesting question because it depends on how you measure that. The number of objects is increasing. In fact, there are studies that show that if we were to stop launching objects altogether, that tomorrow and the next day after that and years into the future, the number of debris objects will actually increase because of the interactions and collisions that will occur in the future. So right now you could say that the situation is getting worse just looking at the number of objects. However, when you take a big picture look and you consider regulations, awareness, companies who are much more focused on sustainability, I think there's a notable increase in the recognition of the issue, and the efforts and investments that are being put towards solving this.

ANNA PLOSZAJSKI

Yeah. I mean, it seems like there's a huge amount of interest in this at the moment. Companies like yours and others trying to tackle the problem. Some of our listeners might have seen the film Gravity, which is all about the risks. Well, a worst case scenario, I guess, of when space debris hits a spacecraft that has humans on board. Is that at all a realistic scenario or what are the real risks to life on Earth for us?

HUGH LEWIS

I think Gravity did a great job in bringing this problem to the public and making it a topic of conversation. So in reality, the kind of phenomenon that was portrayed in the movie would have to take far longer to play out. So we're not talking about minutes, we're talking about decades, centuries. For that kind of thing. Obviously that would be a very boring movie to sit through. So ultimately, we've done studies that show if we continually provide the fuel for those collisions, so the objects that we're launching, then yeah, we can get to a situation where collisions are happening quite frequently.

ANNA PLOSZAJSKI

Yeah. And is there a risk that it would affect our life on earth? You know, I'm thinking if satellites are colliding and getting damaged, would we risk phone signal and GPS and the things, as you've said, that we've come to rely on.

HUGH LEWIS

Yeah, you're absolutely right that those kind of services you could argue are kind of like lifelines, life support to our society. If you think about natural hazards that can occur, we rely upon satellites to keep us informed, to guide response, to manage the recovery. And so without those services, you we'd be facing, I think, some quite horrendous situations on the surface. But whether or not humans are affected, it's not just about services. There are actually physical risks that can arise. The process that satellites and launch vehicles and other things go through as they re-enter the atmosphere, that heating is delivering chemicals into parts of the atmosphere where there's a chance that they cause harm to the ozone layer. That they might affect climate change. Those things have real meaningful impacts to everybody on the planet.

ANNA PLOSZAJSKI

Mike, do you agree with that? Is there anything that you'd add in terms of the risks and sort of why you're doing what you're doing?

MIKE LINDSAY

Yes, I definitely agree. And I think I said earlier, it would have been great if we started this years ago. Solving the problem is not easy. It's a technical challenge that Astroscale is actively solving, but it's not just technical. There needs to be policy changes that help support this. There needs to be recognition of the business case as well. I think when we look at this issue, sometimes we focus on what happens 100 years in the future. As Hugh mentioned, this process can be distant, but it always gets worse over that timeframe. Worsening means that there's higher risk for science missions, for commercial missions, their expenses go up, so it impacts their revenue generation. Some people may have issues even accessing space. As a hypothetical, it could go that direction sooner than later. So we need to start investing in this more today because it's going to take a while before we start noticing the positive impacts of remediating the environment.

ANNA PLOSZAJSKI

I wanted to briefly ask, perhaps Mike .. Could you take us through the Kessler effect, what it is and why it's useful for us to think about?

MIKE LINDSAY

I could, I'm happy to. I think Hugh Lewis is the expert here. I don't mean to punt it off, but I just think he's the best person to explain the physical phenomenon.

HUGH LEWIS

It feels somewhat like passing the buck here, Mike. So, okay. The Kessler effect, Kessler syndrome, I think is Something that's become popularised, it was actually, I think, a joke. It was named for the chief scientist of the orbital debris office at NASA, Don Kessler, who with colleagues there proposed this theory that if we didn't get on top of this space debris problem, we'd potentially end up with a debris ring or debris field around Earth. He proposed a mechanism by which this would happen, which was essentially collisions between objects that are in orbit. These generate fragments. Those fragments can then go on and hit other objects. What people refer to as a chain reaction, a collision cascade. The reason it's a joke is because one of Don Kessler's colleagues proposed the name and it stuck. And I don't know how Don feels about it, having this named after him, but it's become a really useful way in to talk about the topic. And the science essentially boils down to the more objects you put into the finite region of space, the more likely it is you have collisions. Those collisions increase the risk of even more collisions until you kind of change the properties of the objects in orbit. You no longer have the big derelict objects. You have lots of smaller objects. I would hope that we would not continue to throw large objects into that kind of environment that we would be sensible. In fact, know, what Astroscale and what Mike, what they're looking at is something actually that Don Kessler suggested back in 1978, which is, you know, remove objects so that they can't be fragmented into these huge clouds. It seems crazy to me that we had the warning back in the 1970s that everybody talks about that work thanks to this popularisation of the concept, yet only now actually starting to see the removal happening.

ANNA PLOSZAJSKI

It's a depressing aspect of human nature, isn't it? That we have to wait too long to act on a problem that has been warned about previously. I'm thinking other types of pollution, climate change, antibiotic resistance, maybe, you know, lots and lots of existential problems. So Mike, what are the solutions? How might we actually tackle this problem?

MIKE LINDSAY

As Hugh mentioned, the more objects you put into space, the more likely it is that you have collisions that then spur more debris and more collisions. So in the near term, it's very important to prioritise the removal of these massive objects, particularly ones in crowded orbits. At the same time, what we're trying to do is support this philosophy of forward thinking, sustainable mindset, instilling this culture of reusability, preparation for worst case scenarios. And this means thinking about the environmental impacts from the day you start designing your satellite. There's various ways you can, you can think about this. You can add redundancy to your satellite. You budget fuel that allows you to move your satellite out of the way of debris. Then when it's done with its mission, it can use that fuel to de-orbit itself and then re-enter the atmosphere safely without posing a hazard to anyone else. Things can and do go wrong with satellites. So even if you do have the right amount of functionality and fuel budgeted, you may experience a failure. Then you'd be left with a satellite that was once operational, but now is one of these defunct objects that we're saying is a hazard to the environment. So one way to protect against that is what we call preparation for removal. So you design your satellite with some features, let's say a docking plate or interface that would allow one of our servicers to then dock with, take custody of your object and remove it from orbit.

ANNA PLOSZAJSKI

How does that work? Sorry to jump in. I just really want to know about the kind of the engineering behind that. How does that exactly work?

MIKE LINDSAY

Yeah. So if you imagine that your spacecraft has lost all control, and you have no communications with it, it becomes tricky to safely approach and to safely dock unless you are prepared with reflectors on board, markers that help you identify the spacecraft features, which then you can assess, okay, how is the spacecraft moving? How is it rotating? And where is the right place to safely approach and then dock with the spacecraft? In this case, Astroscale's docking plate is a ferromagnetic disk. So it responds to magnetic fields. And that allows us to have a literal magnet on our spacecraft that will approach, dock, and then the magnetic forces keep them held together. So now you have two spacecraft that essentially become one, and you can control that derelict satellite and safely bring it out of orbit. I think it's important at this point to say that this is not sci-fi. In fact, there are hundreds of satellites in orbit today that have docking plates. These docking plates come from a company called Altius. And in March of 2021, Astroscale launched its first mission to demonstrate that we can approach one such docking plate. In this case, this was on a kind of a dummy satellite that launched by Astroscale, we can approach and dock with that docking plate using magnetics. So at this point, we've proven that that methodology works and we call this our end of life service.

ANNA PLOSZAJSKI

Amazing. I'm sure that that's what the Spice Girls were thinking about when they talked about 2 Become 1. It's about satellites and recycling. Hugh, can you take us through any other technologies or the kind of the cutting edge of the engineering that is being looked at at the moment or being trialled?

HUGH LEWIS

Yeah, happy to. So Mike talked about the docking plates and spacecraft that have been prepared. But then there's also the question of what do you do for objects in orbit that haven't been prepared? Overcoming that, I think, is quite difficult. Something that struck me when Mike was talking is that the ideas that Mike's talking about are actually simple. Magnets, little reflectors on a spacecraft. You know, we have these kinds of things. We see these things every day. Sometimes the simple ideas there are the best way to go. So, and that's true of some of the ideas that have been proposed for dealing with these unprepared objects. For example, nets have been suggested, harpoons, you know, and again, these are really, really old technologies. But I always come back to the systems that have been proven in orbit because you want to also reduce the risk and make sure that they work. And we have flown plenty of missions that have used things like robotic arms. And those missions have been proven in orbit and we understand those. The question then is what do those robotic arms grab on the derelict objects? For some, as I'm sure we're going to discover, it's actually really quite tricky. In other cases, you actually have parts of the object that you can access. What's important is we use technologies that we know are going to be reliable. And in some cases that means that they're the things that we're really familiar with and potentially quite simple.

ANNA PLOSZAJSKI

I love that, the simple engineering solutions being the most effective sometimes.

MIKE LINDSAY

Yeah, Hugh, you're talking my language. I say that because Astroscale is actually at this point contracted by the Japanese space agency JAXA to remove a derelict upper stage rocket body from orbit and that's exactly the methodology we're using. A robotic arm that will deploy and then grab onto this very known feature that we know is very stiff, it's strong. It was built to support the satellite during launch. And so this adapter ring is what connects the rocket to the satellite. So it's very strong point, that is exactly where we will approach the rocket body and where we will grab it and take custody of it with a robotic arm.

ANNA PLOSZAJSKI

I was just going to make a silly point about how like, actually, maybe it's not a silly point. In the future, ideally, it sounds like we need all of these objects to have a universal adapter, basically. Like we need a USB-C equivalent for satellites. So the little WALL-E robots or your craft, they're up there to tidy them up. We'll always be able to dock on and we'll always be able to securely attach.

HUGH LEWIS

Yeah, absolutely. I mean, it's not a silly suggestion at all. I think this point about preparing your spacecraft that Mike was talking about, I think is vital. Once the spacecraft is finished, get them out of orbit. It provides a way, even if your spacecraft were to fail, that's the thinking behind it. It just adds this extra layer of reliability, redundancy that could make the difference.

MIKE LINDSAY

Yeah. And having a known interface point also, it ensures that the docking and taking control is a very safe operation that preserves the client spacecraft as well. And if you want to start thinking long-term and addressing these issues such as depositing materials into the upper atmosphere during reentry or the risk of harming life on earth, long term we need to start thinking of maybe not burning up everything that we launch into space. We want to support a circular economy in space. So having a known interface or a robotic arm that can grab a satellite safely and then maybe bring it someplace else to be reused or recycled, that's a very enabling feature for the future of sustainable space.

ANNA PLOSZAJSKI

And do you think that's going to be possible?

MIKE LINDSAY

Yes, absolutely. In fact, our US office is working with a partner. The study that they're doing right now is looking at how we can collect space debris. And again, instead of burning it up into Earth's atmosphere, we can bring it to a sort of foundry or processing plant in space, harvest the aluminium, reform it into let's say a rod that can then be fed into a type of propulsion. So the space debris now becomes fuel for other spacecraft. What I envision for the future is that once more people realize that we can dock with satellites and start to reuse the materials, that they will actually start to design their spacecraft and use materials that are easier to recycle in the future or structures that can be reconfigured.

ANNA PLOSZAJSKI

One thing I was thinking when you were both talking is this is starting to sound very much like a culture change within the industry needing to happen. People accepting ideas of reduce, reuse, recycle, I guess.

HUGH LEWIS

Yeah, it's a paradigm shift. It's a transition from single use disposable spacecraft to reusable spacecraft, which have multiple uses, long lifetimes and so on. But every part of our system at the moment, essentially says that's an impossible thing to do. We have debris mitigation guidelines that say you have to dispose of your spacecraft once it's finished. So if you're operating in low Earth orbit, as part of your license to operate, you may be mandated to send that spacecraft back into the atmosphere to burn up once the mission is finished. So we throw it away. And in some places, that's a law that you have to follow. So there's not just a technical transition that's needed. There's also a policy transition that's needed. And I think both are hard, but I think companies like Astroscale and others are demonstrating the technical side of things. Whilst behind the scenes, Mike hasn't said this, working really hard on the policies and getting those ready, getting those to a position where they're actually going to serve and work with the technical developments and innovation as well.

ANNA PLOSZAJSKI

Hugh, Mike, we've got to wrap up our conversation. I'm sorry, I feel like we could talk for so much longer about this, but thank you for inviting us into your world. It's one that at the start I knew very little about actually. I wonder if you could, yeah, each give us maybe your hopes for the future. Where do you see us in 10 years from now?

MIKE LINDSAY

Yeah, in 10 years, I think we're going to be seeing much more frequent missions like the ones that Astroscale is doing. To generalise, this means that one spacecraft can safely approach and interact with another spacecraft. And I think this will be very beneficial because these in-orbit services will first enable the removal of derelict objects, but we will also provide life extension of satellites. So this means a satellite that has lost its functionality. And then there are future services that we will be enabling such as refuelling, refurbishment, part replacement, reuse and recycling as we discussed. So we want a much more sustainable environment so that we can see more value come out of it.

HUGH LEWIS

For me, what I kind of have seen over the last 10 years is this huge shift. This commercialisation of space. And over the next 10 years, I think that's only just going to accelerate. And I think what that does is it brings in the power of the consumer. Consumers want choices, they want things to work. And we've seen, I think, how that works in relation to things like climate change. Those kind of things will actually increase the connection between people on the ground and space. And that, I think, is what I'm hoping will start to drive companies, governments towards the business models that Mike was talking about, towards the sustainable solutions, the power of the consumer.

ANNA PLOSZAJSKI

Thank you. It's been so interesting to hear your insights and I'm really looking forward to following what happens next. So thank you both for being here and for sharing those. Well, that was a fascinating discussion and I mean, what a multi-pronged engineering problem. I mean, it really has got it all, robotic arms, tricky policy aspects, massive commercial pressures and that all too familiar question of whether we are actually going to get ahead of the game for once. But I have to say, you know, chatting to Hugh and Mike, it does make the clean-up of our orbit feel possible and if there's one thing I know about engineers, it's that the sky is never the limit. You've been listening to Create the Future, a podcast from the Queen Elizabeth Prize for Engineering and Peanut & Crumb. This episode was presented by me, Anna Ploszajski, and was produced by Jude Shapiro. It featured Professor Hugh Lewis and Mike Lindsay. To find out more, follow QEPrize on Twitter, Instagram and Facebook. Thanks for listening and see you next time.