Skip to Content

Podcast: The satellite boom that threatens to clog the skies

We’re entering the era of satellite mega-constellations, but so far there are no rules for how to avoid collisions in orbit
April 7, 2020
Yoshi Sodeoka

Deep Tech is a new subscriber-only podcast that brings alive the people and ideas in our print magazine. Episodes are released every two weeks. We’re making the first four installments, built around our 10 Breakthrough Technologies issue, available for free.

Every two weeks, give or take, SpaceX puts another 60 Starlink communications satellites into low Earth orbit. Its initial goal is to launch 12,000 of these small mass-produced satellites—six times the number of operating satellites currently in orbit—with another 42,000 possibly to follow. Other companies such as Amazon, Telesat, and Planet are planning their own satellite “mega-constellations.” The result could be a welter of new space-based services, from Internet connectivity to continuous mapping. But there’s also growing attention to the potential downsides, including an increased risk of collisions that could end up littering low Earth orbit with dangerous debris and rendering it unusable. In this episode of Deep Tech, we hear from OneWeb founder Greg Wyler and science writer and former astrophysicist Ramin Skibba about efforts to mitigate the hazards.

Show Notes and Links

Satellite mega-constellations, from the March-April 2020 print issue, p. 22

Sky’s the limit, from the March-April 2020 print issue, p. 30

The number of satellites orbiting Earth could quintuple in the next decade, June 26, 2019

Episode Transcript

Wade Roush: Far above our heads a couple thousand satellites circle the planet… helping us do things like communicate, navigate, and forecast the weather. It took decades to put that many satellites into the sky. But soon, they’ll be joined by tens of thousands more. It could turn the orbits closest to Earth into something like a freeway at rush hour.  

Greg Wyler: We all thought the ocean was big, right? You just throw your bottles in there, who cares? But it's not big. And all these environments play on each other and affect each other. And you think about space, it's sort of big, but the objects are moving at 17,000 miles an hour. That's a lot of coverage every second.  

Wade Roush: At that speed there’s no such thing as a fender-bender. One collision can generate a catastrophic volume of space debris. 

Ramin Skibba: If everybody does whatever they want with the night sky, then at some point you're going to have satellite collisions that make low-Earth orbit basically unusable. It could take many billions of dollars and many decades, seriously, until low-Earth orbit is usable again.  

Wade Roush: The new generation of  satellites could help us achieve all sorts of goals -- like Internet connectivity for everyone on the planet. The problem is, there aren’t any traffic cops up there to set and enforce rules of the road. We talked with the experts about how space companies are dealing with the lack of regulation—and what could happen if the congestion in low-earth orbit gets out of hand. 

I’m Wade Roush, and this is Deep Tech.

[Deep Tech theme music]

Wade Roush: it won’t be long before Earth is blanketed in a cloud of new satellites. While that brings new risks, it should also bring some huge benefits, including providing new services like broader wireless Internet connectivity and nearly continuous mapping of the Earth’s surface. That’s why the editors of MIT Technology Review decided to put satellite mega-constellations on this year’s list of 10 Breakthrough Technologies. And to write about that development, the magazine turned to a San Diego-based science writer and former astrophysicist, Ramin Skibba. 

Wade Roush: So, Ramin, tell us what a satellite mega-constellation is.

Ramin Skibba: Right. So a satellite mega-constellation is not like a constellation of stars like Ursa Major or whatever. But it is like a constellation in the sense that they are associated with each other. So you could have just a couple of satellites or you could have dozens or hundreds or even thousands all coordinating with each other.

Wade Roush: How many conventional satellites are there in orbit and how many more are coming? How many of these constellations exist as yet?

Ramin Skibba: Just to give a ball-park numbers, there are a couple of thousand satellites in the sky. But we're talking about not just thousands, but really tens of thousands of more satellites coming up soon. And so there's a couple of major players involved, like Space X, Planet Labs and One Web. Those are the three biggest. And then, of course, NASA and the European Space Agency and other space agencies are also working on these satellite constellations.

Wade Roush: According to Ramin, what’s enabling all this is a combination of engineering advances, such as smaller electronics, and a new generation of ion thrusters that use tiny amounts of fuel.

Ramin Skibba: So you can do in a shoebox-sized satellite what you would have needed a suitcase-sized one before to do. And that matters because it's cheaper to make and cheaper to launch. Now you can fit, say, dozens of these satellites onto a single rocket.

Wade Roush: One promise of these new satellite constellations is that they’ll help bring Internet access to the 3.5 billion people who still don’t have it. But no one’s really regulating this revolution. And no one’s forcing the companies to come up with a way to make sure their satellites won’t collide in orbit. On top of that, nations such as China, Russia, India, and the United States have all tested missiles designed to blow satellites to smithereens.

Ramin Skibba: I mean, the movie Gravity with Sandra Bullock really brought it home for some people.

[Audio clip from Gravity]

George Clooney: Houston, update?

Ed Harris: Well, we have a full-on chain reaction. It’s been confirmed that it’s the unintentional side effect of the Russians striking one of their own satellites.

Astronaut: They shot down their own satellite?

George Clooney: Right of disposal. Most likely a spy-sat gone bad. Now it’s shrapnel.

Ed Harris: The debris chain reaction is out of control and rapidly expanding. Multiple satellites are down, and they keep on falling.

Wade Roush: Ramin says some aspects of the film were very realistic. In 2007 China destroyed one of its own weather satellites in a test of its anti-satellite missile technology. 

Ramin Skibba: Just thousands of bits of debris were created by this single missile hitting a single satellite. It's not that hard to imagine a conflict in space that creates this time not thousands, but even millions of bits of debris. It really is a situation where at some point there could be too much debris. And so right now it's critical that more debris is not created. That should be the number one concern.

Wade Roush: What can satellite builders do to minimize the chances in advance that their satellites won't wind up as space junk?

Ramin Skibba: So yes, there's a lot of things that satellite operators can do. I would say Planet Labs is one of the ones that have been very conscientious about this. Most of their satellites, they’re in low-Earth orbit. And they’re designed so that when they’re no longer useful, they fall down towards the Earth and then they burn up in the atmosphere.

Wade Roush: So they're so low to begin with that they basically are guaranteed to fall back into the atmosphere, just because of friction or something?

Ramin Skibba: That's correct, yeah. So air resistance slows down these satellites. And then they start falling. For satellites that are higher up, air resistance is so close to nothing that that won't work. And basically they have two options. One of them is, if there's a propulsion system on that satellite, they can move it down to a lower orbit and then pull the same maneuver. Or if they're so high up, they can push the satellite up to a higher orbit. It's called a graveyard orbit. And so when you're that far from the earth, the odds of a collision are basically negligible.

Wade Roush: But what about when unexpected things happen? Last month SpaceX launched a mission to put 60 more of its small Starlink communications satellites in orbit.

SpaceX launch announcer: Five. Four. Three. Two. One. Zero. Ignition. Liftoff…

Wade Roush: This is a recording from the company’s webcast.

SpaceX launch announcer: And there is that live view. So you can see on your screen the satellites are slowly separating away from the second stage. And over the next few weeks they will distance themselves from each other and eventually use their onboard ion thrusters to make their way to their final orbit.

Wade Roush: There are now 360 of these satellites in orbit, out of a planned 12,000. But the most famous Starlink satellite is probably Starlink 44. Last year, as it was changing orbit, a European Space Agency weather satellite had to fire its thrusters to get out of its way. Maybe they never would have hit. But maybe they would have, and as we prepare for a world with tens of thousands of satellites in the sky there needs to be a plan for how to prevent accidents.

Greg Wyler: It's a very interesting area of law, and if you like space law or you like international law this is going to be a big topic.

Wade Roush: Greg Wyler founded telecommunications company OneWeb. The company actually went bankrupt last month, an economic casualty of the coronavirus pandemic. But until then it had plans to launch 2,000 of its own satellites, and las fall, at our EmTech conference, Wyler talked to our executive editor Michael Reilly about his experiences trying to build a safe mega-constellation even in the absence of regulation. We're going to listen for several minutes, because in this conversation Wyler and Reilly covered several questions that show how tricky space law is. The first: who's liable if one satellite hits another?

Greg Wyler: Whoever is the launching state takes responsibility for any damages they cause.

Michael Reilly: Okay.

Greg Wyler: So in most countries, if you launch, you're required to take out insurance against damage you might cause. So if a satellite hits something else, you're liable and the state's liable because usually the company's not gonna be able to pay for the damage, cause the damage, the magnitude of the damage can be much larger than any company.

Michael Reilly: Sure.

Greg Wyler: I mean, maybe Amazon. And maybe not even Amazon, if you think about the potential ongoing damages of taking out the space station or something like that.

Wade Roush: Wyler went on to explain that because space is essentially unregulated, OneWeb designed its satellite constellation to be what he called "naturally safe."

Greg Wyler: Like literally there’s no one at the wheel right? There's nobody. The FCC put out an NPRM - a Notice of Proposed Rule Making on space debris. Didn't do anything about it. Commerce says ‘We're going to take control,’ but they don't have the regulatory authority to take control. FAA hasn't said anything. They said “That's above this line, it's not us.’ So what we did at OneWeb was right in the beginning, I put together a team to deal with space debris and we designed our constellation so it was naturally safe. What I mean by naturally safe is that as the satellites are orbiting, if they all break, they don't hit each other. It's a very key piece of it. Now, if you design a constellation that is not naturally safe, it means you require active maneuvers to not hit each other.

Wade Roush: Even though there's no FAA for space, Wyler told Reilly that there are actually a lot of useful parallels with air traffic control in the aviation world that could be applied to managing collision avoidance in space. It's just...nobody's applying them.

Greg Wyler: I'm a pilot, so used to flying and you have levels that you're flying and over time the spacing, the vertical spacing has gotten narrower, and narrower. So you're trying to get better vertical spacing, closer and closer, but you have to have knowledge of where you are. You have to have somebody at the controls. Now you could say, I'm going to do it all automated and do it in an AI world. I'm not prepared to do that in a plane. And I'm certainly not prepared to do that in satellites, because I might be able to use AI to figure out my own stuff. But now I've got all these other people and how do their AI systems work with my AI systems, since there's no rule set. What if we both turned right or left or one turns right one turns left or one goes up or both go down. So there is no short term, five-year term way, to automate collision avoidance. Okay? You can automate collision discussions, you can automate understanding of it, but lights out collision avoidance—that's not even on the table as a safe possibility in the next five years.

Michael Reilly: Okay, so what do we need to do? I'm curious about who becomes a traffic cop, and what does the traffic cop look like when we're not just talking about say American airspace we're talking about low earth orbit.

Greg Wyler: So what I had hoped would happen, hoping that the US would take a forward looking stance on this and senators were writing into the FCC and saying you should do something. And a lot of people started talking about this. The US should craft a rule, a set of rules, and they should then say to the world, ‘Since we have a lot of satellites, we're going to force this on our satellite systems and we're going to ask you to adopt these rules and create an international agreement on it.’ Didn't happen. And they have a whole set of rules. You can go look it up on the website, but they haven't acted on it. But the FCC is not in charge of space. They're sort of in charge of licensing for spectrum rights to use space, which is kind of a gate... But you could launch a satellite that doesn't use FCC spectrum...

Wade Roush: But even if satellite companies and governments do eventually get a handle on all this, science writer Ramin Skibba says there’s another problem with satellite mega-constellations. The more satellites there are in low-earth orbit, the more often they get in the way of ground-based telescopes looking at the night sky.

Ramin Skibba: Quite a few astronomers are upset about mega-constellations because of how they affect their observations. I mean, they're bright enough and they're big enough that they can affect a decent number of images. And so it's a real challenge for astronomers. And it's not just the technical challenge. I think it's also the principle of it. They're not too happy about just the possibility of satellite constellations messing with their science.

Wade Roush: We invited SpaceX to participate in this podcast, and they declined. But the company has said that it’s going to great lengths to make sure its satellites don’t become space debris. Starlink satellites can maneuver out of the way when there’s a detectable risk of a collision, and in fact the company said it would have moved Starlink 44 out of the way of the ESA weather satellite last September, except there was a bug in its paging system that prevented Starlink operators from seeing ESA’s warnings. In addition, the company says aging Starlink satellites will use their on-board propulsion systems to deorbit before they die, and that even if the propulsion fails, the satellites are in such a low orbit that they’d fall back to earth within one to five years anyway. And on the question of how to keep the satellites interfering with ground-based astronomy, here’s what the SpaceX announcer had to say during the webcast of that March 18 Starlink launch that you heard earlier.

SpaceX launch announcer:  One quick update. As many of you know, we’ve been running a number of tests to reduce the reflectivity of the Starlink satellites on their way to orbit. The first of these tests is using paint to darken portions of the satellite. Preliminary results show a notable reduction. But we have a couple of other ideas that we think could reduce the reflectivity even further, the most promising being a sunshade that would operate in the same way as a patio umbrella or a sun visor, but for the satellite. The sunshade option is slated for a future Starlink launch. And all of these efforts are ongoing, and we’ll continue to report results back as we receive them.

Wade Roush: So, Ramin, it feels like the larger issue here is that we just don't have a set of rules to govern space commercialization or space development. Do you think we're getting any closer to having some kind of international agreement or some way of operating that will minimize the harms and maximize the benefits?

Ramin Skibba: That’s a good question. I think both at the national level and international level, agencies and institutions need to catch up. So developments are happening a lot faster than laws are to regulate them. There is a push to develop legislation for this. But I think it will take a few years before anything has a chance of passing.  And at the international level, the United Nations does have a group that is working on these issues as well. But to some extent, my impression, and it could be wrong, but my impression is that the international groups are sort of following the US's lead and the US hasn't had a whole lot of leadership on this. There's going to be pressure on companies to pay more attention to these issues. But that pressure may come more from public pressure than from political pressure. So I think it was more, like, news stories and  people complaining about SpaceX messing up their night sky that affected SpaceX. It’s not like a Congress member or someone from the Trump administration called up Elon Musk and said, ‘Hey, you’ve got to work on this.’

Wade Roush: A lot of environmentalists speak about the tragedy of the commons, which goes back to an idea from philosopher Garrett Harden in the 1960s. And I think specifically he was using a metaphor about cattle grazing on a common parcel of land. And if everybody used up their allotted portion of the land by putting more and more cattle out there, eventually there'd be no more grass. And so I wonder whether you think there's some danger that the same situation will occur in space. Will we have a tragedy of the commons where unregulated access ends up making low earth orbit basically unusable for everybody?

Ramin Skibba: Right. I think the tragedy of the commons is a good analogy for this situation. You know, there's limited space. Space should be for everybody. The night sky should be for everybody. But, yeah, if everybody does whatever they want with the night sky, then at some point you're going to have satellite collisions that make low-Earth orbit basically unusable. If you end up with that cascading effect of collisions, it could take many billions of dollars and many decades, seriously, until low-Earth orbit is usable again. It’s a situation that really should be avoided at all costs. And right now, it is kind of the Wild West up there.

[Deep Tech theme music]

Wade Roush: That’s it for this edition of Deep Tech. This is a podcast we’re making exclusively for MIT Technology Review subscribers, to help bring alive some of the people and ideas you’ll find in the pages of our website and our print magazine. But the first four episodes cover our annual 10 breakthrough technologies issue, and we’re making those episodes free for everyone.

Deep Tech is written and produced by me and edited by Michael Reilly and Jennifer Strong. Our theme is by Titlecard Music and Sound in Boston. Special thanks this week to Ramin Skibba, Margot Wohl, and Greg Wyler. I’m Wade Roush. Thanks for listening, and we hope to see you back here for our next episode in late April.

Deep Dive


The Biggest Questions: Are we alone in the universe?

Scientists are training machine-learning models and designing instruments to hunt for life on other worlds.

The Biggest Questions: Why is the universe so complex and beautiful?

For some reason the universe is full of stars, galaxies, and life. But it didn’t have to be this way.

This startup wants to find out if humans can have babies in space

SpaceBorn United wants to conduct an IVF experiment in Earth’s orbit to pave the way for long-term space missions.

Inside NASA’s bid to make spacecraft as small as possible

When it comes to exploring the solar system, we must grapple with the hard limits of physics.

Stay connected

Illustration by Rose Wong

Get the latest updates from
MIT Technology Review

Discover special offers, top stories, upcoming events, and more.

Thank you for submitting your email!

Explore more newsletters

It looks like something went wrong.

We’re having trouble saving your preferences. Try refreshing this page and updating them one more time. If you continue to get this message, reach out to us at with a list of newsletters you’d like to receive.