Ep. 591: Space Junk

Remember the good old days, where there were only a few thousand living and dead satellites? Those days are long over. We’re now entering an era where there will be tens of thousands of satellites, not to mention the spent rocket boosters and other space junk. What kind of a risk do we face and what can be done about it?

Download MP3 | Show Notes | Transcript

Show Notes

AAS Meeting

Can scientists fill the science journalism void? Online public engagement with science stories authored by scientists (PLOS ONE)

The Atlantic

Washington Post

Los Angeles Times

Universe Today



Space debris by the numbers (ESA)

Types of Orbits (NASA)

Satellite Drag (NASA)

International Space Station (NASA)

U.S. Satellite Destroyed in Space Collision (SpaceNews)

India tests anti-satellite weapon (SpaceNews)

The Kessler Syndrome (Space Legal Issues)

Solving the space junk problem (CU Boulder Today)

Prototype Satellite Launched on SpaceX Rocket Will Try to Clean Up Space Junk (Popular Mechanics)

Robotic Refueling Mission (NASA)

The Forgotten Cold War Plan That Put a Ring of Copper Around the Earth (Wired)

Haystack Observatory (MIT)

Lincoln Laboratory (MIT)

Clusters, not constellations, pose biggest orbital debris risk (SpaceNews)

Project West Ford and the plan to pollute space (Boston Globe)

How to cast a wider net for tracking space junk (MIT Technology Review)

Kilometer-Long Space Tether Tests Fuel-Free Propulsion (Scientific American)

Planetary Society

LightSail 2 Launches to Space to Soar on the Power of Sunshine (Smithsonian Magazine)

Space Junk Solution? Tiny Cubesat to Test New De-Orbiting Thruster (Space.com)

Satellite uses giant net to practice capturing space junk (The Verge)

Here Come the Space Tugs, Ready to Tidy Up Earth’s Orbits (Wired)

China Has a Plan to Clean Up Space Junk with Lasers (Universe Today)


Transcriptions provided by GMR Transcription Services

Fraser:                         AstronomyCast, episode 591, What Are We Gonna Do With All That Space Junk? Welcome to AstronomyCast, our weekly facts-based journey through the cosmos, where we help you understand not only what we know but how we know what we know. I’m Fraser Cain, publisher of Universe Today. With me, as always, is Dr. Pamela Gay, a senior scientist for the Planetary Science Institute and the director of CosmoQuest.

                                    Hey, Pamela, how are you doing?

Pamela:                       I’m doing well. It’s a new year. We just survived covering the American Astronomical Society meeting and the days are finally getting longer, thanks to the tilt of the Earth tilting towards the sun. Go! Go, tilt!

Fraser:                         I heard a really troubling stat and I haven’t looked into it too deeply, but that before the internet age, there were about a hundred newspapers and television stations that had specific science journalists who specialized. There was a science section of the newspaper, a science section of the news. There were specialists. I can remember some of these people. We’re now down to one.

Pamela:                       Oh, dear.

Fraser:                         Essentially, the career, the job of the science journalist is no longer existent in traditional newspaper – the newspaper industry. Which means that if you’re getting your news from the newspaper, at best, you’ve got somebody who is covering a bunch of things trying to report on science news. Which is –

Pamela:                       Or freelancers. There are some amazing freelancers out there and also folks writing for various magazines. The Atlantic, for instance, regularly hires excellent science writers to write stories. But that’s not the same thing as having your salary, your insurance, and everything else you can count on, just to write science.

Fraser:                         I’m sure it’s just a matter of time until that number is eventually zero.

                        On the one hand, obviously, as a digital, science-based journalism machine that is Universe Today, we got you covered. But you’re not gonna find out about us in the Washington Post or the LA Times or whatever. You’re gonna have to come looking. And so there is this lack of just general science news that’s making its way into modern reporting at a high level of quality that’s able to give people the nuance, the skepticism that’s important for being able to properly digest science news.

                        I don’t know what the answer is. Obviously, for me, obviously everyone just come read Universe Today. But that’s not the answer. The answer is somehow to build proper science reporting back into the DNA of more general news organizations. I don’t know what the answer is. It’s sort of freaking me out.

Pamela:                       Now Media is actually really helping to, hopefully, start a new thing. At least I hope this is the start of a new thing, where they’re running this show as well as the Daily Space on a regular basis. And we’re so grateful to be out there in front of all of you in Houston. If you like this, please tell other people, “There’s this way you can go get science.” Maybe we can start a trend. Maybe we can make the cool shows in the evening not just about what’s in entertainment but what’s also out in the universe.

Fraser:                         All right. Well, we will get on with this week’s show but first, a message from our sponsor.

                                    This episode of AstronomyCast is brought to you by Universe Today. If you want space news, you should come to Universe Today. It’s the best place for space news. Space news, space news.

                                    And we’re back.

                                    Remember the good old days, when there were only a few thousand living and dead satellites? Well, those days are long over. We’re now entering an era where there will be tens of thousands of satellites, not to mention the spent rocket boosters and other space junk. What kind of risk do we face and what can be done about it?

                                    We stand here and, obviously, I am contributing as a beta test user of Starlink. I am part of the problem. But there is a lot of space junk, lots of satellites, more mayhem, more mischief. Set the scene. Where do we stand in the junkification of the universe?

Pamela:                       We are currently at a place where it is very hard to near impossible to keep up with just how much stuff and fragments of stuff is orbiting our planet. A few years ago we could easily say there is exactly 2,000-some-odd satellites. At any moment exactly how many that were functional and orbiting our planet, while at the same time there were hundreds of thousands of pieces of space junk, of shards of this, that, or the other thing that had been dropped (wrenches, golf balls), all orbiting our planet, constantly being tracked.

                                    Nowadays, we have a variety of different communications companies that are orbiting constellations of thousands of satellites, such that as we record this today, with a Starlink potentially launching between now and when this show airs, I’m just gonna say there’s more than 6,000 satellites functionally orbiting our planet and just shy of a million pieces of junk joining them in those orbits.

Fraser:                         But I think it’s important to break up the junk into groups because some are really bad. Others seem bad but they’re actually almost entirely harmless. Can we segment the space junk into the stuff that is up there and seems concerning but it’s actually probably not a big problem?

Pamela:                       The probably-not-a-problem stuff is dead geosynchronous satellites that have been lifted up into parking orbits. These are missions that no longer either have the fuel, the energy, or just the ability to control themselves; that before they got shut off, before they got completely worn down, they lifted themselves up into a high enough orbit that they’re not in anybody’s way and they’re just going around and around our planet, a little over 24 hours per orbit as they’re not quite in geosynchronous space.

Fraser:                         They’re gonna stay up –

Pamela:                       Forever.

Fraser:                         – essentially, practically forever.

Pamela:                       Yes.

Fraser:                         Maybe in a few million years the interactions with the sun and the moon and the Earth will kick them out of Earth orbit and they’ll orbit the sun. But the chances of them causing any kind of mayhem… And they are moving even out of geosynchronous orbit when they die, so that they are very safe.

                                    At the other end of the spectrum, we have the stuff that’s very close to the Earth and that stuff is actually surprisingly safe, as well.

Pamela:                       The stuff that’s the closest in to the top of our atmosphere, it doesn’t last very long once it breaks down because the drag of the atmosphere is just slowing it and slowing it and slowing it until, very quickly, it falls out of orbit, deteriorates in our atmosphere (assuming it’s small enough) and we might get a great spark of light streaking across the sky in its final crash through the atmosphere. But it doesn’t really have an opportunity to crash into anything before it does that final plunge. So, this close-in stuff, the atmosphere takes care of it for us and we are grateful.

Fraser:                         Right. People keep bringing up this argument, even about Starlink; about how Starlink is – they’re gonna be sending up, eventually, tens of thousands of these satellites?

Pamela:                       Yes.

Fraser:                         But they’re only orbiting at an altitude of about – I think it’s about 350 to 500 kilometers. So, they’re sort of in the same place that the International Space Station is. They’re a little above the Space Station. And they are under constant deterioration of their orbit. The only way they can stay up is that they’re constantly having to fire their krypton ion engine. Without that, within just a couple of years at the most they’ll all just reenter the Earth’s atmosphere and burn up.

So, in fact, having a lot more satellites flying closer to the Earth is better. What’s the worst is the stuff that’s in that middle range. And we’ll get to that in a second but first we’ve gotta have a break.

Pamela:                       Well done!

Fraser:                         I can be professional.

                                    And we’re back. Let’s talk about the dangerous stuff, the stuff that’s too close to the Earth to just drift away harmlessly; the stuff that’s too far from the Earth to get nicely cleaned up on a regular basis; the stuff that’s in the middle.

Pamela:                       Yeah. There was actually a case a few years ago of a Soviet dead satellite crashing into an Iridium communications satellite and leaving behind order of 2,000 shards of former spacecraft. This is what happens when you have something that is in orbit, is dead, that may sometimes just happen to cross the orbit of something else because it’s not like all the satellites are going in one direction. If you get two satellites meeting in the night, that crash is going to fling pieces in all directions, entering both higher and lower orbits.

Fraser:                         Right. Yeah, yeah. We saw that with – there was a recent anti-satellite test that was carried out by, I think, the Indians, about a couple of years ago. They blew up one of their satellites. They thought, “Okay. It’s just gonna – it’s a low-flying satellite. It’s almost dead. The debris is all gonna enter the atmosphere. It’s fine.”

                                    But no. Some of the pieces went low and crashed immediately. Others are still flying around a year plus into the test. And it looks like it was a terrible mistake. Some which could potentially even interact with the International Space Station.

When you get these kinds of collisions, you don’t just get this nice, little debris cloud that maintains the same orbit that the satellite was there before. You get chaos. And chaos makes chaos.

Pamela:                       And the problem here is that exploding cloud of debris ends up forming a belt of debris around the planet as some of the pieces move faster, some of the pieces move slower, and as they end up with different velocities in all the directions around their orbit.

So, we’re running into problems where the lower orbiting ones can get annoying because you have to sometimes wait to launch a vehicle for something to get out of your way as you go to a higher orbit. But that’s something we can generally plan around. It’s annoying when you have a two-minute delay that suddenly becomes a 20-minute delay because of that thing that has to move. But if you instead end up with a belt of debris you may not be able to get to the orbit you want from the place you want to launch if this becomes a serious problem.

So far, we only have these few incidents. There’s been a couple of purposeful satellite tests. There’s been that accidental collision. But things in the middle ranges, we’re going to eventually have to figure out a solution for as that space gets more and more crowded. Those things may eventually come down; very, very slowly getting dragged on by the tiny amount of atmosphere that is still up at those heights. But we’re adding things faster than things are coming back. It’s becoming a crowded space.

Fraser:                         So, give us the worst case scenario.

Pamela:                       The worst case scenario is you have some of the larger satellites that are up there collide and create entire bands of debris that are areas that aren’t safe to put spacecraft. And we have to figure out how to go gather up all the small stuff. It’s sort of like cleaning your house. It’s a lot easier to clean up a cardboard box that your dog hasn’t shredded.

Fraser:                         Right. Yeah. But imagine if the pieces from the cardboard box, to really stretch your metaphor; if the pieces from your cardboard box, any other box that they touch explode those boxes into other little pieces, and you live in a box factory.

Pamela:                       Yeah. This is like a Christmas day nightmare of cardboard boxes, wrapping paper, everything else shredded in all directions, but attached to moving objects.

Fraser:                         Yeah. Yeah. That are moving 28,000 kilometers per hour.

                                    There’s actually a name for this, called the Kessler Syndrome? I think so.

Pamela:                       Yes.

Fraser:                         This idea that you just get this chain reaction of satellites crashing into other satellites, creating debris fields, shifting to different orbits, reaching other satellites, grinding those satellites up, until you get to this point that you’ve got this impenetrable shield of shrieking metal that surrounds planet Earth. And we talked about this: the stuff that’s low down interacts with the Earth’s atmosphere, returns safely. The stuff that’s high up, you’ve got some spaces, some gaps you could get through. But the middle stuff, the stuff that’s in the 800 to 1200 kilometers high, it’s never going away, and you can never clean it up except one fragment at a time. And as you wait, every second you wait, they just get smaller and smaller, into smaller pieces of metal, until you’re trapped on Earth forever.

Pamela:                       And one of the hard parts about this problem is there are amazing teams of engineers who have been out there partnering with various space agencies since the mid-80s to develop spacecraft capable of going out, grabbing dead satellites, and either dropping them into lower orbits or moving them into higher orbits; essentially, getting them out of danger’s way. But while we’ve had the prototypes under development, going from inexpensive (relatively speaking) prototypes to actually expending the money to make a space-borne vehicle and expending the money on a launch, that final motivation is only now starting to be seen. And it’s not being seen in terms of picking up space junk. It’s being seen in terms of “We finally have the ability to go glom onto old satellites and, essentially, refuel them.” And that’s only been down twice, so far.

Fraser:                         We’re gonna talk about solutions in a second, and one of, I guess, the worst examples of unintended consequences that I think I’ve heard in space junk. We’ll get to that in a second, after the break.

                                    This episode of AstronomyCast is brought to you by CosmoQuest. If you love finding rocks, measuring their size, just day after day, hour after hour, if you’ve never wanted to hate an asteroid more, you should join CosmoQuest. They’ll put you to work categorizing rocks, finding landing sites, hating asteroids.

                                    And we’re back.

                                    You told me a story before we started today that I had never heard of. Tell me about this.

Pamela:                       I really can’t believe I didn’t know about this until recently, either. One of our good friends of the show, Gordon Dewis, was telling me about a specific form of space junk that was launched in 1961 and 1963, called either Westford Needles, Project Needles, or Project West Ford. This name caught my attention because I grew up in Westford, Massachusetts. I was like “Huh. I wonder if they have anything to do with each other.” Even though I come from a small town that basically has two things: apple orchards and Haystack Observatory. Well, it turned out it has everything to do with Haystack Observatory’s location, which is MIT’s Lincoln Labs.

                                    Back in the 1950s, when we were just starting to see the rise of the Cold War, there was a lot of concern that the transoceanic communications cables could get purposefully cut by the Soviet Union. We only really had two ways to communicate around the planet at that point. We could either bounce radio signals off the ionosphere, which is a hit or miss thing that really depends on stuff like weather and solar activity, or we had the transoceanic cables. The idea was if we launch a whole bunch of little tiny reflective surfaces that are halfthe wavelength used for communications into orbit, they could scatter all those radio signals back down, essentially reinforcing the ionosphere, making this communication something that works more consistently.

                                    There was order of 500 million, less than two-centimeter long, roughly thin-hair sized needles of copper launched into a medium-sized orbit, where some of it continues to be today. There are over 30 clumps of these needles still in orbit. One of the clumps actually came down a couple of weeks ago, which is how this came to Gordon’s attention and then my attention.

                                    When this was first done, scientists around the world were like “Bad idea!”

Fraser:                         Oh, good!

Pamela:                       “Do not do this, U.S.!”

Fraser:                         At least people understood that at the time.

Pamela:                       And this, apparently, didn’t stop us. But so far, these haven’t caused a huge problem. And part of the reason they haven’t caused a huge problem is they only had one successful launch of this program. All the successive plans to launch more of these into belts around the planet were cancelled. So, we have deteriorating belts of little tiny needles that were planned out in my home town of Westford, Massachusetts, and are great if you’re a ham radio operator and want something to bounce your signal off of and you know exactly where to point, but otherwise are a special misbegotten mistake of doing things without understanding their consequences.

                                    Luckily, shortly after they started launching these things folks realized we can just launch communication satellites and so instead of launching things to bounce radio signals off of we just started launching relay stations.

Fraser:                         Much smarter idea.

                                    It’s just the example of somebody – like somebody saying, “Oh, I really miss Scotland. I wish I could have a Scottish broom in my garden here on Vancouver Island or in New Zealand.” That’s all we have now. It’s everywhere. Unintended consequences. We have tons of invasive species. There’s plenty of examples in the past where someone just thinks of this idea and they just do it. Then we suffer the consequences of it for decades.

                                    Let’s talk about what we can do to mitigate this problem. How can we, I guess, minimize creating new space junk and then how can we clean up the space junk that already exists?

Pamela:                       The first thing that we have to do is track the space junk. We’re doing this with radar facilities. Ironically enough, Haystack Observatory at that Lincoln Labs, where the Westford Needles were developed, is now one of the places doing the tracking. So, it first created the junk; now, it watches the junk.

Fraser:                         It’s only fair.

Pamela:                       This helps us learn just what kinds of things we have to worry about. It allows us to know okay, we want to launch things that have the ability to get out of the way of other stuff. So, once you’re on orbit you need the ability to maneuver. We now have a plan that once things are launched, not only do they regularly get out of the way of other missions, but before they run out of fuel they’re supposed to put themselves someplace safe; either deorbiting by coming down through the atmosphere or boosting themselves up out of the way into a parking orbit, a graveyard orbit, if you will. That’s step one: have an exit strategy and know how to dance when you’re on orbit.

Fraser:                         And there’s been some pretty clever ideas for this. Not just – you talk about thrusters. There’s been some ideas about a tether that you unreal from the bottom of your spacecraft. It can be very small and very light. It actually only adds a couple of kilograms to the weight of your satellite. They can even be involved on cubesats, miniature versions of these. Imagine: you’re dragging behind this 10-kilometer long wire that is dragging you back down to the atmosphere. What might take you decades, hundreds of years to come back through the atmosphere happens over the course of a couple of months. So, you’ve got lots of great ways to, fairly inexpensively and not very difficultly, to make your spacecraft crash back into the atmosphere.

Pamela:                       And these space tethers, there’s been some really good articles and work done in collaboration with the Planetary Society. We look forward to seeing all the ways that people find to take advantage of tethers, light sails, and things that, like you said, aren’t propulsion that allow them to move around on orbit.

Fraser:                         That’s fine for the future satellites. Each one has to have some mechanism for returning itself back into the atmosphere or into the ocean or into the cosmic graveyard. What about the stuff that was launched before anybody thought that this was maybe a problem? Some satellite that is too high. It’s gonna be there for a few hundred thousand or a thousand years. It’s a potential to crash into other things. It’s dead now. What do we do with it?

Pamela:                       This is where we are seeing a few different kinds of plans. One is to use little tiny things that you go, maneuver yourself up to one satellite, and then in a single use, bring that satellite either up or down, pick a direction. So, you can launch a bunch of, essentially, cubesat thrusters that each go and take care of one piece of junk that’s big enough to grab hold of.

                                    A lot of stuff isn’t big enough to grab hold of. So, there’s also plans to build what, essentially, to me is not sporty in any way. It looked like giant baseball mitts of net to go up and sweep up stuff and then gather it up and bring it down. Then there’s the idea of having – some of the coolest designs I’ve seen look like giant Os, giant doughnuts flying through space, that will go up, grab something, move it, let go, go grab something else, move it. So, you essentially have these reusable flying tugboats.

Fraser:                         I think the biggest problem that people need to understand is that it’s not like a – you say tugboat. So, you imagine this boat is going putt, putt, putt and it’s moving around the ocean. It goes over to one piece of junk and it grabs it. It goes over to another piece of junk and grabs it.

It’s not that. It’s each piece of junk, and we talked about this, that there are tens of thousands if not already 100,000 pieces of junk of various sizes from a centimeter up to spent rocket boosters. Each one has its own special trajectory that it’s moving at; say, seven to eight kilometers per second. So, each one is like trying to catch a bullet. So, if you wanna catch one, you have to launch your spacecraft, you have to match orbit with it. You grab onto this thing with your little tweezers and then you hug the booster. Then you and the booster crash into the atmosphere. Well, you just spent 100 million dollars to launch one of these little catchers. One down, 99,000 to go. Launch your next rocket to grab one more little piece of space junk, dock with it, take it down. The scale is incomprehensible to try to bring these down.

Pamela:                       And this is where you really have to see it in terms of taking care of things in a band around the planet. I always imagine this sort of like in old westerns, where you see the person on horseback racing down to catch the runaway carriage and somehow getting from the back of one horse onto the runaway carriage. It’s that order of chaos but at thousands of times faster speeds.

Fraser:                         So, one satellite will grab one and then it will have a cone of catchability that it can move on to another and maybe it’s got one more in the can. Then it goes down.

Pamela:                       You’re gonna take care of things that are in a roughly equatorial orbit, inclined 20 degrees with a node in a certain place. You can take care of things roughly in this one orbital band. Then you have another one that takes care of things in another orbital band. We have satellites orbiting essentially around the equator on various inclinations and we have things orbiting the poles. So, there are things essentially at right angles to one another.

Fraser:                         Yes. And when they collide they will –

Pamela:                       It’s bad.

Fraser:                         This problem is only gonna get worse. They’ll put them into new directions.

                                    There is one idea that can solve all our problems but it means putting a weapon of mass destruction into space. That’s a gigantic laser. Let’s talk about this idea.

Pamela:                       With a laser, you can literally push things around. The idea is you simply launch an energy-guzzling, massive laser that works in probably something like the infrared and you use it to, hopefully, push into new stable orbits and not destroy. If you destroy, if you pop a satellite, you have just made your problem worse.

Fraser:                         Yeah. What you’re wanting to do is you’re wanting to zap the satellite a little bit so that a little piece of it vaporizes and you’ve made a little thruster, a random little thruster off the side of your – off your space junk. So, you’re sort of – as these pieces of junk are flying past you’re going zap! And each one gets a tiny little thrust and over time this laser can just be tracking piece after piece after piece and just shooting at everything that comes by and slowly pushing them all down.

                                    But the downside is a satellite-killing laser in space.

Pamela:                       And no one wants to let anyone else have the responsibility for something like that. If no nation wants to let any other nation do that, it’s one of those things that’s great on paper (also terrifying on paper) but is probably never going to happen unless the international community agrees on some very special who-do-we-let-control-this agreements that in this current world I don’t see happening.

Fraser:                         I think we painted a kind of dystopian possibility for the future. In all the reporting that we’ve done, the one that’s most likely over the long term is that it just adds additional risk. It is this additional cost of doing business; that you will lose more and more satellites. It will become more and more difficult. There will be more damage that’s done. It’s just friction to the entire future of space exploration and it’s gonna suck. And the sooner we get onto this the better.

Pamela:                       The future will tell. But until then, we’re just gonna watch those nearly a million pieces of debris and those over 6,000 active satellites and hope that their paths never cross.

Fraser:                         Exactly.

                                    Thanks, Pamela.

Pamela:                       Thank you, Fraser. We’ll see you next week.

Fraser:                         Right.

                                    Do you have names for us this week?

Pamela:                       I do. While we’re like fancy pants now on television, we don’t have any commercial sponsors yet. So, we rely on you to keep this content coming week after week. This week I wanna thank Ben Lieberman, Bill Hamilton, Joshua Pierson, Jack Mudge, Richard Riviera, Syndie Walker, Alexis, Thomas Sepstrup, Nicole Vorisek, William Andrews, Jeff Collins, Harald Bardenhagen, Arcticfox, Marek Vydareny, BenFloss, Elad Avron, Nate Detwiler, Ron Thorrsen, Phillip Walker, David, Karthik Venkatraman, Gfour 184, Andrew Stephenson, Donald E Mundis, Scott Bieber, Father Prax, Anitusar, Rachel Fry, Matt Newbold, Antony Burgess, Steven Shewalter, Dean McDaniel, Jen Greenwald, Bart Flaherty, and Dean.

Thank you all for being out there and being our patrons that allow us to do what we do and to have Richard, Nancy, Ally, all of them out there putting together our show, getting things on YouTube, on the various podcatchers, and hopefully every week improving our quality bit by bit.

Fraser:                         Thank you, everybody. And we’ll see you next week.

Recording:                  AstronomyCast is a joint product of Universe Today and the Planetary Science Institute. AstronomyCast is released under a Creative Commons Attribution license. So, love it, share it, and remix it but please credit it to our hosts, Fraser Cain and Dr. Pamela Gay. You can get more information on today’s show topic on our website, astronomycast.com.

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