The new prime real estate? Earth’s orbit

0:00A live short, daily news podcast focused on just one story. But right now, you probably need more. On Up First from NPR, we bring you three of the world's top headlines every day in under 15 minutes. Because no one's story can capture all that's happening in this big, crazy world of ours on any given morning. Listen now to the Up First podcast from NPR. There are about 15,000 satellites whizzing around the planet right now. Since these small spacecraft are now essential for everything from GPS and mobile connectivity to broadband, internet and scientific data collection, there are people whose whole job it is to try and keep them from crashing into each other. And governments and companies around the world have announced plans to add almost two million more satellites in the next few years.

1:00From KERA in Dallas, this is think, I'm Chris Boyd. Outer space may be endless, but there is actually a finite amount of prime real estate for objects launched into Earth's orbit. As my guests will tell us, many entities seem eager to get their satellites out there before any regulation might try to limit them. And at present, experts are not even sure how many would be too many to manage safely. Jonathan O'Callaghan is a freelance space journalist. His article in Scientific American is titled Battle for the Night Sky. Jonathan, welcome to think. Hey, thanks very much. Thanks for having me. We ought to start by explaining what we are talking about here. The satellites that have been working for decades to say transmit TV and radio signals. Those are actually installed in geostationary orbit, right? What does that mean? Yeah, sure. So geostationary orbit is a very high above Earth. We're talking about 35,000 kilometers. Typically, people probably think of satellites as these big bulky machines.

2:05Maybe they take months to build maybe years. For a long time, you might get a launch slot. Eventually, the satellite will launch good as base. But things have changed dramatically in the past five years. And satellites now are churned out as quickly as items of clothing. Some companies are building satellites multiple times a day. We're seeing stacks of them launched together like pest dispensers. It's changed from these being one of machines that one satellite might do a whole host of things to, here's a hundred satellites ready to go, let's launch them and put them into space. So geostationary satellites are quite literally few and far between. When we talk about plans to add hundreds or thousands or millions more, these are the ones that would be much closer than the kilometer translates to miles as 22,000 miles away. What is different about how satellites are placed in low Earth orbit?

3:05Yeah, so with geostationary orbit, you're kind of always over the same points on Earth. So that's useful for your TV satellites because you might be, you might have a country that served by a couple of satellites that provide TV stations just to that country or to that region. So having one satellite overhead works quite well. But if you want to provide a service around the globe, maybe to multiple countries or to everyone, then you need your satellites to be a lot lower so they can orbit the Earth quicker and cover more of the surface. So that is when you want to go down to low Earth orbit, then we're talking out to a few hundred miles and these satellites are whizzing around the planet once every 19 minutes or so. You think about the International Space Station, that orbits in low Earth orbit about 400 kilometers or 250 miles above Earth. So it's relatively easy for astronauts to reach, but it also covers a lot of the ground as well. You can see it in the sky.

4:06And the same is true with satellites down in low Earth orbit, that they're trying to cover lots of the Earth. It's also easier to reach, need less fuel. And you can put many, many satellites here. You talked to an astronomer who moved to a farm in Saskatchewan in part so she could view the night sky without a lot of urban light pollution. Turns out those dark skies also make it pretty easy to glimpse constellations of satellites. What do they look like? As a constellations are these massive groups of satellites that we're seeing. You probably might have heard of SpaceX's Starlink constellation, which now has 10 million users and counting. These are big groups of satellites. They are in the thousands, if not tens of thousands, and maybe one day millions. And they encompass the Earth, essentially. They provide constant streams of data with Starlink. It's beaming the internet back to the ground. So you can access the internet anywhere on Earth surface by connecting to Starlink.

5:06The goal is to make sure there are enough satellites in space to handle the demand from millions and millions of users. But we didn't really predict the rise of these constellations. No one really knew that you could orbit so many satellites in space. Maybe back in the day, we might have thought a few hundred in one group was a lot. But SpaceX now has 10,000 in its Starlink constellation, actually 10,700 at last count. And this thing is enormous. And we just didn't know you could actually do this in SpaceX to the credit option. You can kind of do it. But there are major concerns with what comes next. So part of it is what they look like in the sky, although that turns out to be ultimately maybe a relatively small part of the concern. What makes them visible though? I mean, they're in low Earth orbit, but they are still pretty small and pretty far away. They just reflect whatever light hits them. Yeah, basically that. They are giant mirrors. Essentially, they have big solar panels to collect energy from the sun.

6:09And they glint. They shine. They appear bright. They are particularly bright just before dawn and just after dusk. So when the sun is kind of low, that kind of twilight lights. And the night sky has kind of got that little ethereal whiteness to it. The satellites appear bright because the light is reflecting off them from the low sun in the sky. But you know, that's a popular time for astronomers to go out and observe asteroids and other parts of the solar system. We're talking, you know, hours of observing time every night. I now kind of littered with these many, many satellites. Now in SpaceX's defense and other companies' defense, they have taken steps to try and reduce the brightness. So they have tried to kind of paint the satellites in their darkened coating. They tried to tilt them so they don't properly reflect down to the grounds. But astronomers are dealing with these things enormously now that, you know, if you use any telescope on Earth, you will encounter satellites coming through and obscuring your view of the

7:09heavens. And some people might argue that's a small price to pay to have internet around the globe and maybe it is. But for astronomers, it does mean that, you know, studying the universe and our beginnings and where we are in space. These are all much, much more difficult now. And those constellations of satellites are designed to work together as part of a system. How does that work? Are they talking to one another and what is the process? Yeah, they have communications with each other. SpaceX is starting to use laser links between it, starting satellites. And they are constantly talking to each other. It's essentially like a big kind of ball-like network to use a Star Trek, that's for. Yeah, they are, you know, the big systems, they're living breathing things, essentially. They can all talk to each other. They all know where each other are and where other satellites are. And they make decisions on the fly, which is very important at the moment because in the past with satellites, they would, to avoid a collision with another satellite, you would,

8:11you know, it would take days or weeks to have a conversation with another satellite operator to ensure you didn't accidentally cross paths or move into them and you decide who might move. But with these big constellations now, they have to make quick decisions. And they do this by themselves, really, that these big living groups of things that are waving in space, they move with the sun's influence as solar flares come in, some of them will, and it's kind of trigger their thrusters to change their altitude. Occasionally, one of them will, will die and its thrusters will run out and they'll be pulled back into the atmosphere. It's a giant living mesh of metal around our planet that is quite fascinating and quite incredible when how it is operating, but a bit daunting at the same time. Even when you have systems that can talk to one another or operators that are in charge of these things, presumably you have the potential problem of like two people passing each other in a narrow hallway, right? Like they both know they don't want to hit each other. They could potentially both step in the same direction and therefore move even closer.

9:15Yes, collisions in space are one of the big talking points at the moment. We've only ever had one collision in space that was back in 2009 when an active American satellite crashed into a dead Russian satellite, producing thousands of pieces of debris, about half of which are still in orbit today, more than 15 years later. That threat of collision is always there. It's always very aware that another collision could render parts of orbit unusable or exceedingly dangerous. And these are called to make sure these don't happen satellites perform collision avoidance maneuvers. So they will look at their motion for the next 24 to 48 hours. Maybe they'll work out where they're going to pass. And if they are going to cross paths or go near to another satellite, one of those satellites will move. A few years ago, maybe a satellite might perform three or four of these a year, quite small. It was quite easy to manage. Now with Starlink, these maneuvers have exploded.

10:16SpaceX reported that in 2025, it performed 300,000 avoidance maneuvers of its Starlink constellation. And it's on track to maybe double that this year in 2026. These are unfathomable numbers, massive amounts of maneuvers. These satellites are dotting each other constantly. Every day there is a maneuver to avoid a collision with another one. And these are going to grow and grow and grow. Yeah, I mean, it's impressive how well it has worked thus far. However, it's like a busy freeway. At some point, even if everybody is trying to follow the rules, more vehicles are going to increase the possibility that two of them will hit. Yeah, I think there's a kind of acceptance that we are going to get collisions at some point, which kind of seems a bit weird to say, but I think we probably will start seeing satellites hit each other in the next few years. And what will come of that, I'm not sure. But the number of constellations launching and the number of satellites launching is so

11:20extreme. It's hard to not see that happening. We mentioned, yes, SpaceX so far. They've done a great job. They have performed probably millions of maneuvers now and they've not had a single collision. They've dodged their own satellites. They've dodged other satellites. They have a really low risk thresholds. They move. If there's any small chance of collision, they'll move out the way of other satellites. And they to their credit, they've done a very good job. But we're about to see other constellations, multiple efforts from China, other efforts in the US and other countries. Are they going to be as good as SpaceX and can SpaceX manage these collision avoidance maneuvers as their constellation grows? Currently, they have 10,000 satellites. What about when they hit 20,000, 30,000? Can they still do it? And can Chinese companies do the same thing? Can Amazon with their constellation do the same thing? We don't know. And that is a big unknown that we are heading towards as these other massive constellations

12:20also begin launching. You alluded to this briefly earlier, but I want to talk more detail about how those avoidance maneuvers even work. What does it take to shift the orbital position of a satellite once it has detached from whatever rocket initially put it into space? Yeah, it's as simple as firing the satellite's thrusters to give it a little nudge so that its path over time will change ever so slightly. The spacecraft can, with SpaceX's starling constellation, can kind of do it itself by having this autonomous system on board. We know from a NASA test a couple of years ago, kind of how this works, SpaceX is constantly kind of keeping track of the satellites and they are constantly tracking their position for the next day or two so they know if there's going to be any kind of risk of hitting another satellite. And if they do see that's going to happen, it's quite simple. They have these special thrusters, these kind of ion thrusters that have lots and lots

13:23of fuel that can last many, many years and they can just give themselves a little burst and make sure that their predicted path for the next couple of days takes them nowhere near the other satellite that they might hit. Does it seem like the autonomous systems to avoid collisions are even better at this than the old way where a human operator had to become aware of the threat and then negotiate with some other human operator elsewhere? Yeah, I mean, they seem to be coping so far. We don't really know the exact details of how SpaceX's system works. A lot of it has kept them to wraps probably for valid reasons because they have several competitors trying to catch up with them. So they might not want to share all of their secrets. But yeah, but then there is a danger that we are relying on SpaceX continuing to perform their autonomous maneuvers as they have done to keep Earth a little bit safe. We are relying on this one company to continue operating this algorithm or program that they run perfectly and flawlessly and how long they can do that.

14:26I don't know, but that is a little annoying. Jonathan, what are the advantages of putting satellites into orbit relatively close to the planet? Is it simply a matter of they are cheaper to launch than something that's tens of thousands miles away? There's a few factors. Yeah, cheaper to launch is relatively easy to reach that region of space, a few hundred miles up. It's not too far. It's the distance between many close major cities on Earth. It's not an unfathomable to kind of imagine. But the main reason to do that is because of the nature of these constellations we're seeing at the moment. So Starlink is an internet constellation. So for it to operate properly, you need to be able to beam the internet from the satellites down to the ground. It's relatively close so that there's low latency when you connect to the internet. People don't want to load a web page through Starlink and have to wait seconds for it to ping up to thousands of miles and come back down again by having the satellites in 250 miles or so orbits.

15:27The journey taken to get that signal up to the satellite and back down again or vice versa is short. And it means that for most people using Starlink, they might not notice much of a difference between that service and an irregular fiber optic service. If they try to do something more intensive and playing a video game down on a large file, yeah, maybe they might start to notice some differences then. But for the most part, it can kind of operate similarly to a fiber system. That's the major benefit really. You want that low latency. You want to give people the same internet service. They would get through their household Wi-Fi connecting to a local internet fiber optic system. Yeah, that's kind of the main use case at the moment. We should talk about some of the reasons we've become so dependent on these. We rely on this technology for one thing to assist people responding to natural disasters that might wipe out land-based communication networks. Yeah, Starlink is a wide variety of use cases at the moment.

16:28If you've flown recently, you might well have connected to Wi-Fi networks on the plane that are powered by Starlink. As you mentioned, natural disaster response. If a country experiences a debilitating earthquake or other events, and it loses its ground-based and trust-rule internet service, having starting dishes is great. You can connect to the incident now. This is why countries are so keen to kind of have their own Starlink networks. China wants to have their own Europe as well. They want to have their own sovereign response to things like Starlink can enable. You can vote out at sea, suddenly it backs us to the internet. They'd never had before. They had access to a very slower satellite internet decade to go. But now they're getting near fiber speeds from this Starlink constellation. Now you can browse TikTok while you're in the middle of the Pacific Ocean. It's wonderful. Or not. Or not. Yeah, or not. But yeah, there are plenty of use cases of it.

17:29It's hard to argue against that, really. I mean, giving internet to everyone from space, it sounds like a kind of worthwhile goal, doesn't it? I mean, why would you not want people in remote locations that couldn't access the internet to suddenly habits? So we have mostly liked what these satellites can do for us. Therefore, it is likely we will keep wanting more. How many more entities are thinking about putting these out there? Like how many have declared plans to launch a lot of satellites? Currently, the tally is two million satellites are proposed to launch the space. So currently there are 16,000 satellites in space. Two million is the number that if you combine all the different proposals from various companies and countries, that is what they're talking about putting into space. Now, this is not a true number. There are probably not going to be two million satellites in space, at least for the foreseeable future. Often these are a bit of land grabs, a bit of kind of attempt to show.

18:32You have these big plans to launch these big constellations. But there are going to be 10 to 1000s added to space. And how many can be added is a very, very interesting question that we don't really know the answer to. It kind of depends who you ask. Some people say we're already at capacity. There are already so many satellites in space that it's too crowded. And even if we stopped all launches today, we disaster is still inevitable. We are still going to see collisions. Satellites will still hit each other, even with the things we've left in orbit right now. Other models kind of propose you could launch maybe hundreds of thousands to millions of satellites if everything worked perfectly, perfectly well. And you had some sort of super advanced rates, avoidance, algorithm that everyone used or some amazing grid mesh, perfect system network. But there are so many factors that play that it's really hard to know exactly how many satellites we can operate in space, which is a little bit worrying,

19:33because we don't really know what we should do from here. Should we keep launching satellites, which we are doing, and they're constantly going up, you know, hundreds are launching every month, or should we kind of slow down, and there's not really a great agreement on that, because some people say, well, space is big, we've got loads of room up there, but there is plenty of space for everyone to operate. And others might say, well, that's true, but some companies like SpaceX have kind of taken the best property already. They've already got the best beachfront property, they've got the best orbits, and now other people that might want to orbit their own satellites in space are kind of running into barriers where we can't really also go to the same place as starting, because they've already got 10,000 satellites here. Let's go to this other slightly lesser further from the beach property that is maybe a bit swampier and more rugged, but you know, might get the job done to some extent. Your article references an agreement that at least sounds almost comically retro. What is covered under the outer space treaty of 1967?

20:36Yeah, one of my favorite treaties. The outer space treaty is kind of the main law that we have that governs all space activities. It says that for us, if things, you cannot lay claim to bodies in space, it kind of bans nuclear weapons testing in space, it says not to be a bad actor in space, not to start a complex in space, kind of the things you would expect, but it doesn't really address like Earth orbit. It doesn't really address constellations. The outer space treaty was written in the 60s when concept of having thousands of satellites in space was just beyond imagination. There was tens to hundreds of satellites being in space at the time. The idea of having tens of thousands to millions was really been ridiculous at the time. So people didn't really expect that one company or country might orbit so many satellites in orbit around Earth and what the outcomes of that would be.

21:36So we are in a bit of a legal unknown at the moment where you can't really lay claim to anything in space under the outer space treaty, but space X have kind of claims large swaths of orbit where their satellites are orbiting, but there's not really a rule or a law that says they can't do that. We're in a bit of a great area right now where you could read it in one of two ways and then decide to act one way or another. But that does bring up the issue that we don't really have a space police. There's no space government that would govern this. The outer space treaty is set by the UN, but is a kind of rule with guidelines that countries say they were here to and if one country did massively break the treaty, I'm sure there would be big ramifications, but having one company launched 10 to thousands of satellites, it's not something we're ready prepared for. Jonathan, I'm not all confessed. I'm not exactly sure how this is administered, but we do have a remarkably effective system

22:39for managing where planes go around the planet and obviously it involves multiple countries. Is there anything like an air traffic control system or is that even possible for satellites? The closest thing we have is run by the US military. The US military operates this regularly updated list of satellites in space and whether they're going to pass close to other satellites. This, surprisingly, is the best thing we have at the moment. There isn't any formal air traffic control or way to manage these satellites in space that there's no space traffic control yet. But even then, that's quite a hard task to do. How would operate that? Who would decide who goes where and so on. But there are efforts to improve this. There are several companies deploying radar systems and other ways to better track satellites in space to know where everything is. There are individuals around the world that out of the kindness of their own hearts

23:41track these satellites and keep very long databases and lists of where everything is in space. There are different companies that are trying to come up with ways to make sure that everything is in order in space at all the time. But it's a bit of a, kind of a having a space traffic control is something that's been talked about for a long time. But no one's really sure how you would do it. Who would do that? How would you cope with so many satellites? Who would fund it? Which country would run it? Who is in charge? All questions that we don't really have answers to. The language of the outer space treaty says that this is a quote, space cannot be appropriated by means of use or occupation. In practical terms, what does that mean for a company like Starlink, which, as you said, is all but overtaken the altitude where its satellites are installed, which I think is like 350 to 550 kilometers above the Earth. Yeah, we don't know at the moment. We don't know where the outcomes of that would be.

24:43What if China or another nation went to the UN and said, hey, they've taken over this altitude. We want to also operate there. There isn't really grounds for how that would progress. And we don't really have a good outcome of that at the moment. So I guess that's just a way to see what will happen. The closest thing we do have to someone that pleases this is the lovingly named International Telecommunications International Telecommunications Union, which is run by the runners part of the UN. And they kind of decide who goes into space and who is allowed to launch their constellations. You kind of go to them with your application and you say, I want to launch 10,000 satellites. And they say, yeah, that's probably OK. They don't tend to say no to anything, but the closest thing we have to a body that keeps track of all the satellites going to space and everyone has to apply to them to communicate back to the Earth so that they do have to kind of say,

25:44well, if you launch this constellation here, you might interfere with this constellation that's already in space. So you might have to hold there for the time being. But they don't really have jurisdiction. They don't really have any way to stop these satellites from launching or to not approve things, although there are talks about refining their processes in the coming years and making them have some sort of bigger say in how this works. But they're kind of the closest thing we have to a traffic controller for space at the moment. Do different national governments around the world have different rules for approving plans to launch a satellite from their soil? Very different. In the US, the FCC is kind of the main body that handles that. And they enfand us to them. They do some checks on these constellations going up. And if you want to launch your constellation from the US, your satellites from the US, you have to go to the FCC. And you have to show they will be safely brought back.

26:44Walk back down from space at some point. They won't impact other satellites. Although the US is looking at rolling back some of this regulation, particularly around launches and environmental concerns around the launches themselves. But remains to be seen what the outcome of that will be. But each country does have its own system in place for approving or denying satellite constellations. We haven't seen any country take a hard line on this yet. No country has kind of said, we're going a bit too far here. Let's rein back this constellation that's been prepared by one of our companies. But in essence, each country is supposed to be responsible for their satellites that are launched by their companies when they go to space. And we have seen some interesting outcomes of that. There's a famous act called the Liability Convention Act, which in the late 20th century, a Russian satellite spread some toxic debris over Canada. And they successfully sued Russia for a few million dollars,

27:47which is one of the only cases in space where we've seen someone actually come up with a legal basis and argue that someone acted inferiously and that there was a negative outcome. So that could be grounds for more things like that in the future. There's not been another case with that so far. But maybe something like that could be grounds for managing this in future. If two countries did come to log ahead so there's some issue in orbit. OK, people may not have even been thinking about toxic materials. Should we be worried that heavy metals or whatever is used to build these satellites could somehow end up in the upper atmosphere and cause problems across a wide swath of land on Earth? Yeah, this is a big, I realize that we've said this, a lot of the things that are known at the moment. But I think it's worth highlighting that this is such a new field. You know, having so many satellites launched so quickly, so often into space, people have really kind of racing to work out what the impacts of this are.

28:48And yeah, satellites can be backed through the atmosphere. Is it is a huge unknown? These things are made of aluminum and other metals. Sometimes they have toxic fuels on boards. They can release aluminum oxide, super particles, carbon dioxide, and the atmosphere. And we do not know what that means for the atmosphere. Currently, a starting satellite reenters Earth's atmosphere every two or three days. That is a satellite, the size of a dinner table made mostly of metal coming back to the atmosphere and burning up. What does it mean to add hundreds to thousands of tons of metal to Earth's atmosphere from space? We don't know the answer to that. But there are efforts to find out. There is multiple European missions on the, it in works at the moment that are trying to work out what happens to satellites when they reenter. Because these are dramatic events. When a satellite comes back through the atmosphere, at the end of its life, it reaches 150, 100 kilometers, it impacts the kind of hotter, thicker atmosphere and it gets torn apart.

29:49It's ripped up in this fiery and furno. It's burnt shreds, it's burnt to pieces. And almost all the time, these satellites are completely decimated by the process, by these very, very hot temperatures, by the high pressure environment. But we don't really know what happens during this process. So there's a European mission in launching next year called Draco that was send this kind of mock spacecraft into space and then bring it straight back into the atmosphere. And it's laden with all sorts of sensors that are going to track exactly what happens as a satellite falls back into the atmosphere. And the big question is, what does happen? What exactly happens when you bring back thousands of satellites back into Earth's atmosphere? Are we looking to get a big impact on the atmosphere? Like we had with chloro-flora carbons that caused a big impact on the ozone in the 90s and we had to bring in the Montreal Protocol to lessen that impact and to stop the hole in the ozone forming? Is it that extreme? Or are we talking about a very small effect on the atmosphere and we don't need to worry too much? Or do we need to completely redefine how satellites work?

30:52Do we need to change what they're made of? Do we need to completely eradicate and remove some of the materials that are used in them? Are those we could massively heat the stratosphere? Cause huge weather systems to change? We don't know. These are all unknown questions and the experiment is happening right now because there are hundreds of satellites reentering the atmosphere every year and we don't know what the outcome of that will be. Jonathan, I want to go back to something you said a moment ago very quickly, very blindly. You said almost all the time. These satellites being brought back totally incinerate when they hit the Earth's atmosphere. Almost all the time is not 100% of the time. Is there a chance that the objects we have put into orbit and then ultimately decommission will have chunks that survive that reentry and fall somewhere and hurt somebody? To put it bluntly, there is a chance. It's a very, very, very, very, very small chance but we do know that satellites can somewhat survive reentry sometimes, a very famous instance of this happens last year

31:54when a starting satellite didn't quite burn up as intended. So SpaceX is part of their due diligence and is part of their license for the FCC. They have to show that their satellites completely burn up on entry so that they're designed to break apart, they get torn apart and that they've shredded to nothing. Nothing made it back to the surface. Except last year when a piece of starting satellite landed on a farm in Canada and was recovered by the farmer who found this piece of debris and said, hey, I think this might be a piece of SpaceX satellite and SpaceX said, yep, it's one of our, it's a very small piece of one of our starting satellites can we have it back please? SpaceX have said this is the only time any piece of starting satellite has made it back to the surface. Whether that's true or not, I don't know, we cannot verify that. It's possible that starting satellites might have fallen to remote areas but they haven't been, where they haven't been tracked and the debris hasn't been picked up. It's possible they might have fallen to the ocean and pieces of the satellites might have fallen there.

32:55We don't entirely know whether these satellites can survive regularly and how much does make it back into the atmosphere. Now, that being said, the risk of a satellite breaking apart and a piece of that satellite landing on a person is so vanishing these more. It is not something to be worried about. These satellites are not gonna fall, the pieces of these satellites are not going to cause any major issues on the ground. We should be keeping tabs on this. We should know whether there are pieces of metal falling back from space to the ground and we should know if they can't necessarily harm people. They could damage buildings, they could damage property, they could damage wildlife. We do need to know what is happening here. So, yeah, ants that would be useful, whether there'll be any more pieces of starting satellite coming back to the atmosphere or any other satellites will have to keep an eye on that. But for the time being, seems to have just been a very rare occurrence that this has happened. Anybody operating a satellite clearly has a vested interest in keeping it from being destroyed by an orbital collision.

33:59Besides the catastrophic risk though, to two spacecraft that might slam into one another because all the fail saves have failed, what sort of hazard is associated with the broken pieces that would suddenly be flying around in orbit? Yeah, the problem with broken pieces of space debris is that you don't entirely know where they are and you don't know exactly what risk they pose to other satellites. To explain, when there is a risk of collision in space, we don't tend to say, oh, look, this satellite is, you know, this big is the size of a table. It might hit this other table-sized satellite. What you say is, I think the satellite is probably about here in space. Give or take tens of meters. So it's going to pass within tens of meters of this other satellite. Let's move them just in case they do overlap because we can't be 100% sure where they are in space. If you have these big clouds of debris, you might say, well, there's this big cloud of debris with lots of pieces of metal that could destroy a satellite. Let's give it a wide burr, so you don't go anywhere near it.

35:00If you suddenly start getting more and more clouds of debris, more debris swirling around, smaller and smaller pieces, some of which we know can impact satellites and damage them, of course, failures and satellites do get hit by small pieces of shrapnel in space that do cause them to have outages or even fail entirely. Then if you can't entirely account for all the debris in space, it starts to render possible at Earth orbit extremely dangerous. And if we did start to see collisions in orbit, which some experts think we are going to see at some point, it could start to see parts of Earth orbit kind of rendered, maybe there'd be a risk threshold, you might say. If you try to launch into this orbit, there's a high risk of collision, you might be hit by some debris, launch your launchers satellite at your own risk, hopefully it will survive. There might be some orbits where we say, oh, there's no debris here, put your things here nice and safely, there's no issue. How far this goes is still a bit of an open question.

36:02What about launching humans into space? If we do start seeing collisions more and more, and we do start seeing more and more debris orbiting the planet, will it still be safe to launch humans and say, okay, these humans can go to the moon, but they might render this cloud debris from this collision a few years ago. That was a big open question. What is the risk threshold of launching humans in a spacecraft that could be impacted by clouds of debris? Still we're still yet to see more of these collisions happening, but I think when we do see another satellite collision, which I think we will see at some point in the near future, that will raise big questions. We'll start to think, what is, how do we assess the risk of Earth orbit and how do we decide how this is going to work with these pieces of debris in space? Taken to the extreme, this problem of space debris could be really catastrophic. Will you explain the Kessler syndrome? The Kessler syndrome is the idea that you could have kind of run away chain reaction of debris in space

37:04as more and more satellites and more and more debris hits each other. So if you've seen the film Gravity from a few years ago, you might remember Sandra Bullock and George Clooney being in space and being somewhat stranded by these clouds of debris swinging around the planet with questionable science, but it was pretty accurate. And that is the risk here. If we do start seeing collisions, those collisions could then hit other satellites. They could be destroyed and form more cloud of debris. You have more and more and more until at some point, you essentially reach this point where any launch to space is going to be destroyed by debris because of the large amount of debris in space. Now, it's hard to say if things will ever get so bad, but some experts argue that we're kind of already in the syndrome. If you stop launches today, we would see collisions at some point in space. If you stop all satellites operating today, you'd see collisions in days and weeks. It's arguable that already there are enough satellites in space

38:06that over very, very long time scales, we're talking thousands of years, collisions are inevitable. And we are already in the cluster syndrome. It's just that the timelines for collisions are very long. As we launch more and more satellites, the syndrome becomes shorter, the time between collisions decreases, and it gets more and more dangerous. But the idea, basically, that there could be these chain reactions of collisions in space is the cluster syndrome. And it's a very, very, very concerned and very worrying because if it did happen, we could be talking about entire networks, entire satellite constellations being taken out of service. Space takes wouldn't want their starlic constellation operating inside a cloud of debris. They'd have to change how that operated. It could affect how GPS satellites work, if it can't be launched anymore to replace other ones. Whole infrastructures now rely on space activities. And if we do start to act irresponsibly and produce these large amounts of debris in space

39:07and head toward this unsustainable chain reaction phase, then that could impact everyone. On the other hand, maybe it's not so bad to be can cope with everything. That's also a possibility as well. Maybe we'll find a limit on satellites and we'll manage to avoid the collisions enough that it kind of works out okay. And the debris will get sweeped back down to Earth safely. That could also be a scenario. We just, we don't really know at the moment, which I think is what is causing a lot of worry among experts. Has anyone been able to float even a theoretical plan for retrieving those orbital projectiles? There's been several debris removal ideas. There's been some satellites are equipped with kind of grappling points where if they died, they could be brought back into the atmosphere and burnt up. People have proposed launching harpoons to capture debris or even giant nets to sweep up debris. There's been proposals to fire lasers from the ground

40:07or in space to heat up debris so that it kind of gets a boost of energy and kind of pushes itself back to the atmosphere. There's no shortage of ideas for how to clean out this debris, but in practice, it's kind of who was going to fund that and is it workable, is it feasible? You know, the idea of bringing back down a couple of dead satellites isn't a terrible idea, but when there are 50,000 satellites, what is one dead satellite among that many? Now, there are actually some steps to remove some of the more dangerous pieces of debris so we've mostly spoken about satellites so far, but there's also giant rockets orbiting Earth that have been kind of discarded there for decades. They were launched and putting these wide orbits around the planet and they are just swinging around constantly. They're the size of school buses. They could at any point collide with each other or the satellites. There are some proposals and some missions ongoing right now to kind of retrieve and remove some of these from space. There's a Japanese mission that's been ongoing, that's been looking at a spacecraft has gone up

41:10to a dead Japanese rocket has inspected it and has worked out how we might bring that dead rocket back down to the atmosphere. So there are kind of steps to look at removing some of the more dangerous pieces of debris, but for these big clouds of thousands of small pieces of debris, and we're talking very small here, centimeters, millimeters, size of an air post, the size of an air post case or smaller, the measures you would need to remove debris of that size is unfathomably difficult and whether we could ever do that, I'm not sure that would be possible. This is really interesting, Jonathan, as scientists try to figure out the kind of maximum carrying capacity of near-earth orbit for satellites, why might climate change have an effect on the ultimate number? Yeah, one study recently has found that as the atmosphere warms, it could change how many satellites can orbit in space. That one of our best ways to keep orbit clean and to keep things safe is actually the atmosphere itself.

42:14The atmosphere can naturally sweep up dead satellites and debris from orbit. So we spoke earlier about lower orbit, being 250 miles above Earth, if a satellite fails at this altitude, thanks to the atmosphere, which is very thin here, but nothing, you experience atmospheric drag. And over maybe five to 10 years, your satellite falls back into the atmosphere, burns up without you doing anything amazing. As you go to higher altitudes, this drag, lessons and lessons, and you don't want to reach about a thousand or more miles, the time scale is for drag to remove your satellite or in the tens of thousands of years, very, very long. But the atmosphere does provide this kind of natural, cleaning remedy for Earth orbit, and theory increases the capacity because it sweeps up some of this debris. But this study last year, I found that climate change through the heating of the atmosphere actually cools some sections of it and it causes it to shrink and lower intensity and this diminishes the sweeping up mechanism.

43:16This study found that the capacity of Earth's orbit could be reduced by half because of climate change. The sweeping effect of this atmospheric drag might massively reduce its climate change increases. And suddenly you lose this natural, amazing space cleaning up remedy that we have. So that is a real possible outcome as climate change continues. That the capacity of Earth orbit could decrease. We've been talking so far about trying to avoid collisions because decent, reasonable people understand how detrimental they could be. Should we worry about deliberate sabotage of satellites in low Earth orbit? Yeah, absolutely. We're seeing more and more attacks in Earth orbit right now. GPS satellites have been subjected to spoofing and other attacks in the past year. There's various risks of... There's long been concerns of some countries kind of settling up to other satellites in space

44:17and kind of inspecting them and getting a handle on them. There's even been rumors that some countries might have... The capacity to launch weapons or explosives or other things into space that could disrupt entire networks like Starlink. Obviously that would be against the outer space treaty but that is a real concern. There are possibilities that if you wanted to wipe out the Starlink network, you could launch a massive EMP or a nuclear bomb and essentially wipe out a huge chunk of the constellation. Now that seems a bit beyond reach right now but if things escalated on Earth and there was a war between a couple of countries, why wouldn't they target these satellite networks that are providing internet to their military and in remote locations? It would seem like a bit of a no-brainer. So that is a concern. We've also seen anti-Satellite tests in the past where countries have deliberately blown up their own satellites with missiles. The US did this, so China and India and Russia

45:20and each time this has happened, it's that in itself has produced big clouds of debris that has orbited the planet but it's also been a demonstration of, well, if we wanted to, we could blow up one of these satellites. Since those tests have been conducted, of course, we now have tens of thousands of satellites whether you could destroy a meaningful number of them with missiles is another question. But yeah, there are concerns there that, you know, a country if it wanted to could take dramatic action and could knock out satellites with a weapon and that could cause huge problems for Earth a little bit. Jonathan O'Callahan is a freelance space journalist. His article in Scientific American is titled Battle for the Night Sky. Jonathan, you've given us a lot to think about. Thank you for the conversation. No worries, thanks for having me. Think is distributed by PRX, the public radio exchange. You can find us on Facebook and Instagram and you can listen to our podcast for free wherever you like to get podcasts. Just search for KERA Think. Once again, I'm Chris Boyd. Thanks for listening. Okay.