- Okay, good evening and welcome to Space Place. This is our guest speaker night, and I'm very pleased to introduce tonight Dr. Lisa Ruth Rand, who is a postdoctoral researcher here at the university. She has an appointment at the Institute for Research and the Humanities and came here from the University of Pennsylvania where she received a PhD in the history of science. So tonight we're going to talk a little bit about the history of space junk. So help me welcome Ruth Rand. 
(audience applauds)

- Okay, great, so, space junk.

So in official policy held by NASA and other space organizations, space junk is defined as anything that's designed and created by human beings specifically for use in outer space that no longer serves a designated purpose or use. This can include objects that remain in space and objects that are returning to Earth through the atmosphere. These are two distinct kinds of space junk, which we will be looking at both of those tonight. 

So what does this include? It can include things like dead satellites. Satellites that we've launched that have run out of fuel, that never worked in the first place, but that remain in space not providing information to the ground. It can be pieces of things that put our satellites and other spacecraft into space, like pieces of rockets that launched those satellites. 

It can be lens caps popped off of space telescopes or surveillance satellites, but also smaller things like errant screws or flecks of paint. Things that are shed over the course of normal operations of spacecraft.

So space junk is produced as a result of rocket launches, satellite operations, and even satellite litter, astronauts, I'm sorry, astronaut litter. So astronauts have dropped things, either intentionally or unintentionally, ranging from tool bags, pliers, spatulas, cameras, and even gloves. So this is the very first America spacewalk. You can see Ed White up in the corner here walking in space. And that is an extra glove that flew out of the door in the middle of his spacewalk in 1965 on Gemini 4. And it was tracked by sensors on the ground until it eventually reentered the atmosphere and burned up.

We've even left waste behind on the moon. Now, this is actually the very first photograph that Neil Armstrong took on his first full spacewalk on the moon in July, 1969.

You can see the leg of the Eagle lunar module in the background there, and what's underneath it is this white bag called a jettison bag, or a jet bag for short. And these jettison bags were commonly used on Apollo missions. They contained a lot of things that astronauts no longer needed, included human waste. 

So what's interesting about these is that they left quite a few of these jet bags on the surface of the moon, and those objects will remain up there indefinitely, so there's quite a bit of human poop on the moon that's going to stay up there much longer than human beings may survive on this planet. So in a later mission, actually, astronauts even threw one of these jet bags out of the window during a return trip to Earth, and they sent it off with a fond bye-bye, bag.

So space, including the moon and orbit, is like any other place that human beings have visited. Where humans go, we create waste, and we've made a lot of it over the course of the past 60 years. So right now there's some 1,100 working satellites in orbit at the current moment. And the rest of the objects that you'll see growing over the course of time in this animation, the rest of these objects are non-functioning space junk. 

And as of April of this year, there are a total of some 18,922 cataloged human-made orbiting objects tracked by the U.S. Space Surveillance Network. But the Orbital Debris Program Office run through NASA puts the total number of objects larger than 10 centimeters in orbit at around 21,000. And this doesn't include small debris. So particles between one and 10 centimeters in diameter, they estimated about 500,000 in orbit right now. 

And particles smaller than one centimeter, a number in excess of 100 million.

So we have all this stuff up here, up in space, but what is it doing? Is space junk dangerous?

So objects in space, especially in orbit, are moving at very, very quick speeds, so particularly in lower orbits, objects can travel anywhere up to seven or eight kilometers per second. So even an object that's very, very small, this is a simulated orbital collision that was taken-- that was demonstrated by the European Space Agency recently. Even objects very small can have a-- can pack a real punch moving at velocities of seven or eight kilometers per second. 

An analogy that's used by NASA is that a piece of debris smaller than a half an inch around, like the object shown here, traveling at about six miles per second could hit as hard as a bowling ball traveling at 300 miles per hour. So it could have a really devastating effect on functioning spacecraft, on spacecraft that we've spent millions or even billions of dollars sending up into space and want to protect. 

Now, I don't know, hopefully some of you have seen or saw the 2013 movie Gravity, in which Sandra Bullock gets kind of walloped by debris and learns to hate space.

And in this movie, spoiler alert, space junk is the enemy. I'll move on from this animation quickly 'cause it's kind of dizzying. The biggest threat in gravity is to astronauts' bodies, right, these uncommonly beautiful astronauts.

The concern is, will they survive with all this space debris traveling at seven or eight kilometers per second?

So this scenario in Gravity, can it happen? Well, not exactly as it happened in the movie.

I'm going to try to, here we go. So not exactly as it happened in the movie, but collisions in space have started to happen with, accidental collisions in space have started to happen, and intentional collisions in space. Now in 2009, this animation shows the very first head-on accidental collision in orbit between a functioning American Iridium satellite and a non-functioning Russian satellite. 

And these two collided over Siberia and created two large plumes of debris circling the globe over their former orbital paths. And so the collision, again, destroyed both satellites and created large, new plumes of debris. This came on the heels of an intentional debris-causing event when China, in 2007, attempted to bring down one of its own defunct weather satellites and accidentally, instead of bringing it down cleanly, destroyed it and created a whole other plume of debris. 

So you can see here, this animation shows the debris caused by that 2009 accidental collision mixing with all of the other objects, both functioning and non-functioning, that are currently in orbit.

So yes, this kind of cascading collision creating debris can happen, of the kind that was shown in Gravity, but not at that sort of instantaneous moment that it happens in Gravity, and not at all orbital altitudes as happens in that movie. And we have evidence that astronauts are indeed threatened by space debris that's currently in orbit. This is an image taken in 2016. This is a pit in the window of the cupola of the International Space Station. Now the astronauts are fine. 

There's multiple layers of glass. They're safe. But you can see here, this is kind of a catastrophic-looking little like impact crater caused by a small piece of debris.

And so it happens occasionally that astronauts do in fact have to take shelter in either more heavily shielded parts of the space station or have to take shelter in the Soyuz module if the space station has a close encounter with a piece of debris or may have a close encounter with debris. 

So the main threat in Gravity, the fictional movie Gravity, is definitely something that, on a much smaller scale, is taking place currently in space, this threat to human bodies, to astronauts' bodies, but not in the same sense in Gravity where an entire infrastructure, which I'll get to in a little bit, an entire infrastructure is taken down within seconds, within minutes, by a debris event. 

And I want to, before we move on, I want to look at one moment from that movie to kind of bring us in a little more closely to think about the threat from debris. So there's this moment in Gravity where the astronaut played by George Clooney is speaking to ground control, and he finds out that apparently most of the all the satellites in space are gone, just gone. And Matt Kowalsky, the astronaut played by George Clooney's response is pretty glib. Half of North America just lost their Facebook. 

Okay, of course with what's happened recently with Facebook and information, I think a lot of people may think that's actually a good thing, but in 2013, this seemed like it was both glib but also, you know, kind of scary. Now, that said, this is again very, very flippant. What's happening on the ground if we were to lose all of our satellites would be very, very, would be much, much more devastating than just losing Facebook.

So I want to ask, how many of you have used a satellite today? Everyone should be raising their hands. I see a few of you aren't, but everyone should be. So there are some obvious products from satellites that many of us use, many of us in America and Wisconsin use every day. Whether the things that are more obvious, like satellite television or satellite, that's by the way, satellite television is much older than kind of these recent consumer products. 

This Elvis Aloha from Hawaii via Satellite from the-- I believe this is early '70s based on his outfit.

You know, this is, satellite television kind of has been a big kind of exciting idea for a long time.

Satellite radio is another consumer product that a lot of people use. And some of you may have, not everyone has this anymore, but you may have had a GPS unit that helps you navigate or you may have used a satellite phone if you're in a more remote area. But even if you've used your smartphone or any sort of a cellphone, not even a smartphone, a regular cellphone. 

If you've ever engaged in banking-- you can see this is just an ad-- but even if you've used an ATM, any sort of financial transaction.

If you've consulted an advanced weather forecast, if you're involved with agriculture, or if you consume products of agriculture, which we all do, that's something that's tied to satellites. Disaster relief, these are images from the Fukushima disaster of 2013.

If you use an airplane, the entire civil air infrastructure is now being increasingly tied into satellites. If you've used WiFi at any point today, you've used a satellite. 

Basically anything that uses time and location switching is often tied particularly to GPS satellites, but all of these products, whether they're consumer products, individual consumer products that you and I might use every day or information that's required by our defense communities or by agriculture or by any number of different industries or communities in America and around the world, so much of what we do every day is tied into satellites. 

And we don't really think about it all that often. Kind of one of the few ways that it's visible on a day to day basis is the occasional sighting of a satellite dish. But, really, what would happen if all of these services just suddenly disappeared?

We would be in some major trouble. And it wouldn't be something that we would necessarily notice right away. So satellites, in many ways-- I like to talk about satellites as being part of an infrastructure. Now, when we think about infrastructure, another example would be the electrical grid, for instance, or the sewage system. Infrastructures are technological systems that provide the backbone of daily smaller technological practices.

And these infrastructures provide that support in a way that becomes invisible, in a way that we don't notice it until it fails. So we don't think necessarily about the electrical grid until the lights go out, and then suddenly you think oh, the lights are off, something's wrong. I can't use my electronic devices, something's wrong. The sewage system fails, things get really exciting then. But we don't think about them when we flush the toilet. It just happens. 

And the satellite infrastructure, in many ways, is even more invisible because I just showed you all of those different kinds of services that are provided that rely on satellites to relay information, but if all the satellites were to fall out of the sky at once like they do in Gravity, it wouldn't be like the lights going off. It wouldn't be something we would see right away. We would almost feel it in our bodies that something was wrong. Things aren't working the way that they're supposed to. 

Our calls get dropped. We can't navigate using our phones like we're accustomed to. We can't get money out of the ATM. You can't-- The Internet wouldn't be working quite right. Things would just stop functioning in a way that was completely invisible. And it would be pretty chaotic, I imagine, should such a scenario happen. 

Now, that said, space policy analysts, both in America and elsewhere in the world, are very concerned about what space junk might do to our critical satellite infrastructure in space. Many of them think that this is a very recent problem and the product of either negligence or ignorance on the part of the American and Soviet space programs during the '60s and '70s. 

And as a historian, this is something that I've been trying to get at the base of for some time now, and what I've found is that space junk is a much, much older problem, and really, we've been aware of it since the beginning of the Space Age. Since Sputnik 1, the very first satellite that reached space, the very first artificial satellite that the Soviet Union launched into space in 1957.

Now what's kind of interesting about Sputnik is, and some of you in the audience may be old enough to remember when Sputnik launched. Some of you maybe even tried to go outside and look up and see Sputnik with your own eyes, and many people were able to do so. I don't have an image of that, it's very hard to find video of the actual object moving through the sky, but I did take a video in Philadelphia two years ago of the International Space Station going overhead, and hopefully we can see this. 

That's the International Space Station, that little star there. And that's Jupiter, just for kind of for scale-- not for scale but for-- 

(audience laughs)

 obviously, but so you can see what I'm looking, well, to show the relative motion. So when those who went out to look for Sputnik with their own eyes would have seen something a little like this. They would have seen what looked like a moving star crossing the night sky. And you can hopefully see here that International Space Station. 

Do you see it moving through the sky relative to Jupiter? So that's what-- I took this in the early evening when the night sky was dark, but the sunlight was still traveling enough around the Earth that it illuminated this object and it made it appear shiny against the dark background of space. So those who went out and looked for Sputnik would have seen something like this, and some of you may have actually done that. 

And now I'm about to ruin your childhood and tell you that that was not in fact Sputnik that you were seeing. So Sputnik itself was only about the size of a beach ball. Even though it was polished to a very high shine, it would not have been visible to the naked eye from the ground. You would have needed at least binoculars, if not a specialized telescope, to see it. 

However, the rocket that launched into space was a good 20 meters long, and the Soviet engineers realized that Sputnik itself would not be visible to the naked eye and instead decided to rig up the core of the rocket that launched into space with reflective prisms that would catch more of that sunlight going around the curvature of the Earth and illuminate it and make it much more visible from the ground. This wasn't a secret. 

A lot of American newspapers published that you could go outside and see Sputnik's companion, Sputnik's rocket companion in outer space crossing overhead at this place and time. But for whatever reason, we've kind of engaged in a collective act of forgetting. What we were actually seeing was a piece of space junk, perhaps the first piece of space junk. Now does it matter? Not really. 

Right, whether it was a piece of the rocket or this object with the trailing mustaches coming off the edges, it didn't matter. Either way it was showing that the Soviets had gotten there first and would inspire either fear or pride depending on your political affiliations. What it really did was provide, regardless of what you were seeing. This was the first encounter that most human beings had with outer space and with the beginning of this time period that we now think of as the Space Age.

Now Sputnik was only the very first, Sputnik and Sputnik's rocket were only obviously the very beginning of the rise of our satellite infrastructure.

And it was kind of this moment where the idea of satellites, being able to use satellites for information became a reality, became something that was full of possibility. And the, you know-- So researchers in America, particularly those who were working for the military, began to think of ways that we might use satellites to communicate, particularly in times of nuclear war. 

And we think of satellites now as being these large objects, or even smaller when we think about these nanosats that are real popular right now, but single objects that have electronics on board that can receive and transmit signals. But that wasn't necessarily the way that satellites started out. There were a lot of different ways, forms that satellites could take from the very beginning of the Space Age. 

And I wanted to give you an example of a kind of satellite that was passive, one that didn't have any electronics on board, but rather the body of the satellite itself served as a reflector for signals sent from the ground. Now you can see here, based on a thumb for scale, these little tiny fibers that are thinner than a human hair and only about a couple centimeters long. Those don't really look like satellites, do they?

But they were. So in beginning of 1958, researchers at the MIT Lincoln Laboratory came up with an idea of creating an artificial ionosphere for use to transmit radio signals from one place on the ground to another point on the ground. And it's actually a really kind of simple kind of satellite form where you can send something up that's very cheap. Those fibers were all made of copper, so a cheap, easily-launched kind of material. 

And they planned to launch some 400 million of these copper dipoles into a ringer on the planet. And, again, you could see a signal could be sent from one point the ground, scattered by the dipoles, and then picked up by a receiver on another point on the ground. And this was something that they did in fact launch in 1961. It did not succeed, and then tried again in 1963 and it did succeed. They were able to transmit a signal from a point on the east coast to a point in California. 

And the researchers who designed this planned to eventually have two different rings, one oriented across the poles and one oriented around the equator. And the plan would be that way you could get to anywhere on the Earth with only one transfer point.

And in many ways this was a really elegant solution to a distinctly Cold War problem. So nuclear war can not only destroy things on the ground, but if a bomb was detonated in space, as both the United States and Soviet Union were doing at the time, it could disrupt radio communications, which means that the President can't communicate with his nuclear arsenal, which could be a major, major problem in the case of a need for a counterattack. 

So this project was a really wonderful solution because it could be launched like that with very short warning, but also because, you know, if you destroy one satellite that has active electronics on board, it's just gone. If you have a field of dipoles, that's something where it can re-congeal, multiple points can be used. 

So it's really, it seems a little strange, and when the 50th anniversary happened in 2015, there were a lot of very interesting articles about the crazy experiment that the United States military conducted to create a ringer on the planet as if it was like Saturn. But, ultimately, it was very much a well-designed, interesting idea for a satellite network.

But when details of the project were made public, astronomers in particular were very, very concerned about these needles. And they brought their protest even to the floor of the United Nations, claiming that no individual government had the right to take risks in outer space without consulting the international scientific community.

They really acted to drum up popular support for their cause in international presses. And eventually even the United States State Department had to enter the fray to mediate the conflict. And in the course of my archival research, I found a really amazing note attached to a file within one State Department official's files that stated, "Astronomers seem to be "a remarkably noisy and parochial group." 

(audience laughs)

 So why were astronomers so concerned about these West Ford dipoles, these copper fibers, thinner than a human hair and only a few centimeters long each? Well, roughly at the time that the West Ford controversy was raging, the first space telescopes were being developed.

And the very first space telescopes were called the Orbiting Astronomical Observatories. And, in fact, we have, next door at Space Place, a--

Sorry, a prototype, I will say, to plug Space Place, their standards for artifacts are in line with the Smithsonian's, in fact, by having these actual, you know, artifacts that were either test models or actually used, which is a really high level of rigor, I think, for a museum, so you have a really wonderful resource here, and I highly encourage you to go take a look at the OAO2 artifact that's on display. So these Orbiting Astronomical Observatories were developed here at UW by astronomers. 

monly used, could not only create problems for astronomy on the ground, that if there were a lot of these needles in space, there might be a lot of reflective material and make it hard for astronomers to observe the cosmos as they had for centuries, but also what might happen if a dipole-type of system were to become common? It could provide either a collision hazard for space telescopes like the OAOs, or the OAOs would have to be put above those dipoles, which would be higher cost, higher risk. 

And space astronomy is something we kind of take for granted right now, but at the time astronomers, many astronomers saw it as potentially revolutionary. So our atmosphere absorbs a lot of the electromagnetic spectrum.

And being able to put a telescope above the atmosphere would open up whole new regions of that spectrum to observation. So those astronomers who were excited about space astronomy saw West Ford, or rather what might happen if West Ford were to succeed, as a major existential crisis.

Now, the test version of West Ford operated as designed, and astronomers were consulted and they were not able to detect it. And, for better or for worse, it never-- It did not become a common form of satellite communications. That said, some of those dipoles are still up there. 

They were designed to come back down over the course of only three to five years, and most of them did, but some of them clumped together, which destroyed their mass to area ratio, which meant that they stayed up at a pretty high altitude. And some of them are even being tracked. If you go online and look at some of the space tracking software, you can actually search for West Ford and see where they are in real time.

So, I bring up West Ford not only because we have this wonderful artifact next door and it kind of demonstrates a very early episode of awareness about the way that we, the kinds of things that we put into outer space and what effects they might have.

So, and astronomers' protests eventually made it into the Outer Space Treaty of 1967. No nation is supposed to launch a potentially damaging mission without consulting with the international scientific community. And astronomers continue to kind of raise the alarm. They did so recently when the Humanity Star was launched, this large geodesic dome or geodesic sphere that was meant to be seen from the ground. It was meant to promote unity among anyone on the ground who could see it. 

But astronomers called it space graffiti. They were very concerned with what something like this might do if it, again, any amount of reflective material in space is something that's an obstruction to astronomers. So this shows, again, that this is, the idea of something--

Excuse me, this demonstrates that space junk has been a concern for a very long time, but also that space junk, like any other form of waste, is open to interpretation. What's one person's space junk is another person's spacecraft and vice versa.

Now, I also want to talk a little bit about the other kind of space junk that I mentioned at the beginning of this talk, the kind that returns to Earth through the atmosphere and lands in the oceans, the oceans that cover three-quarters of the planet's surface, or, in some cases, even hit solid ground. It's very rare, but it does happen. Now, again, some of you might remember one of the most famous incidences of a reentry that did hit solid ground. 

This was when Skylab, the very first American space station, fell to Earth in 1979. I just realized that it was July, 1979, which is exactly a decade after the first moon landing, so I feel like this is kind of an interesting milestone.

So when Skylab fell to Earth, it was done in a matter that they could no longer control it. They didn't have a way of controlling where it would land. And this inspired a lot of kind of macabre humor around the Earth, around the planet, this idea that eventually people would wear target kitsch and, you know, Skylab hit me, there were tinfoil hats that people could wear and cut out and protect themselves from Skylab. When eventually pieces did reenter, they fell into a remote part of Australia. 

Several large pieces were recovered, and one of them even was featured in the 1979 Miss Universe pageant in Perth. 

(audience laughs)

 And the local government fined NASA $400 for littering. And that went unpaid until relatively recently when a disc jockey, I believe in either Texas or California, raised the money and paid them back. So that said, that was kind of one of the most widely known, widely feared reentries in the Space Age, but we even had one pretty recently. 

Hopefully some of you may have noticed within the recent months there was this concern that the very first Chinese space station, Tiangong-1, was reentering in an uncontrolled fashion. And eventually it did reenter on April 2nd of this year. But you can see it was about the size of a small bus, and-- a small school bus-- and there was a lot of concern about what might happen, again, if it were to fall over dry land. 

And for a while there, Wisconsin, southern Wisconsin was kind of in the path of possible reentry landing sites, and people were kind of really scared about what might happen, but the likelihood of it hitting ground was still so tiny because, A, the atmosphere destroys a lot of what falls back to Earth, and, B, the likelihood that it would fall in the ocean was so high. So this was actually an image of Tiangong-1 as it began to reenter. 

And, again, I wanted to show also some of the very terrified headlines that were circulating in recent months about what might happen, again, if things were, this thing was falling, it could crash anywhere, we don't know where it's going to fall.

And a colleague and friend an astrophysicist that I know, Jonathan McDowell, who is an expert on space debris, noted that he's constantly saying it's not a big deal, but nobody ever wants to hear that. They want to hear about the catastrophic possibility that someone will get beaned with a space station.

So as I mentioned, when things fall back to Earth through the atmosphere, this happens on a pretty regular basis, what goes up must come down, whether that happens over the course of weeks, months, or even millennia, everything that we put into orbit will eventually come back to Earth.

Our atmosphere does a really wonderful job for us in exerting pressure and friction and heat on objects that reenter. Typically they break apart, dissipate in the atmosphere, and any pieces that do survive typically fall into the ocean. So three cheers for the atmosphere for doing that work for us, because it's really hard to clean up outer space, which we'll get to in a moment. So thank you to the atmosphere for doing that for us.

But in instances like Skylab, things did fall back to Earth and did hit the ground and, more importantly for us here at UW Space Place, one of the few instances of recovering a piece of debris on solid ground happened not that far from here in Manitowoc in 1962 when the spacecraft Sputnik 4 landed in the middle of the night in the middle of a residential street in the middle of the town. 

And two policemen were called to stand guard until the government officials could come and examine this strange piece of metal and its concrete crater that it had produced. And not long after, two Soviet state officials came to Manitowoc to claim the remains of what turned out to be this Soviet satellite. 

Now, all that remains in Manitowoc now of this event are a ring in the middle of the street showing where the crater used to be, a cast of the fragment that was recovered, and this plaque near the ring on the sidewalk saying that a satellite fragment was recovered at this site in September 6, 1962.

And for the last 10 years, every year the town of Manitowoc has held a Sputnikfest to commemorate the event. And you can see it always draws kind of a feisty crowd. They have a reenactment of the event. They have green burgers. They have a Miss Space Debris pageant.

And people have a great time. 

t many Wisconsin residents are aware of, but I highly encourage you, the anniversary is coming up in September, go out to Manitowoc, enjoy Sputnikfest, and go into the Rahr-West Art Museum where they hold the festival and go take a look at this casting, because that's also when they block off the road and you can go take a look at the ring I've gone a couple times now, and you have to be careful with the traffic, but they shut down the road for Sputnikfest, so it's worth going and taking a look. 

So we have these two kinds of space junk here, right, we have the kind that stays up, the kind that falls down. So what. Okay? Now, often times when we think about space junk, it's often portrayed again, like not only in the movie Gravity, but just in general when you read about it in the newspaper or see videos online or hear podcasts, it's often portrayed as this major problem that space is really congested with junk. 

Now, that said, there's a lot of space in space, right? If you go up there, you're not going to see things whizzing around. It would be very rare that you might run into something. But that said, there have been some close calls. I mentioned with the International Space Station there have been moments where space telescopes, of which the OAO is an ancestor, have had close calls with space debris. 

For instance, the Fermi Gamma-ray Space Telescope had to be moved in 2012 because controllers on the ground were concerned that it was going to collide with a piece of debris. So they had to light up the thrusters and push it a little forward, and it was a risky maneuver given that it had been very, very cold and the engines hadn't been used. But luckily it succeeded, and this piece of astronomical hardware is still being used.

So there's the concern about the spacecraft that's in space, but also concerns about what happens when large objects fall back to Earth because there's always the possibility that it might fall somewhere, or even if it doesn't fall somewhere where people might be living, it could still cause environmental harm. These satellites often have dangerous hydrazine fuel on board. 

In some cases there have been nuclear materials on board that have threatened both human and non-human habitats on the Earth. So what do we do about this problem?

Now, the solutions kind of tend to fall into two categories. There's the idea of mitigation, which is creating less debris and letting the atmosphere and gravity and friction take care of our problem for us, which many of us think is a really wonderful, elegant solution to the problem. But then there's the idea of remediation or active removal. And that's something that's much sexier, particularly in America where we have our startups in Silicon Valley and we love to create new things. 

So there have been a lot of different models and ideas of how to clean up outer space of junk. There's some ideas, they range from using fishing net technologies, ancient fishing net technologies to wrap around debris and make it reenter the atmosphere and burn up. The laser broom, which would use a ground-based laser to clean things up, which even when I see this image, it scares me, 'cause that just looks like space war, and we do not want space war. 

The Swiss have come up with this idea called CleanSpace One. They've already launched the cube set that they plan to take down with this grasping technology. I don't have an image of this one, but I believe that Airbus has designed a harpoon that just got launched by SpaceX. They're going to try to launch into a larger satellite, which, again, I'll get to in a moment why that's complicated.

NASA has come up with an idea to, based on a gecko's feet, to be able to grasp an object like gecko's feet do without a lot of velocity. So, you can see here on the upper right, there's one NASA researcher pretending to be a piece of space junk, the other is using the prototype, and he's just grasping him. You can see he doesn't have to launch. 

He can just kind of approach, grasp, and he's able to move this person there, they're in an airplane doing a parabolic flight path that allows them to experience microgravity for short periods of time. That said, this idea of active remediation, the active removal of debris, is very legally complicated because, as I mentioned before, one person's trash is another person's treasure. 

So if we were to go up and, say, take down an old satellite, an old Russian satellite, it's not necessarily a given that the Russian government would be happy about that, right? We have to be absolutely 100% clear that what we're taking down is either ours and that we have permission to take it down, or that everyone's on the same page with how objects, how space debris is being taken down and destroyed. 

And there's always the risk that things might go wrong, like the 2007 anti-satellite test that China conducted. If we were to send up a harpoon, like Airbus is trying out, and that high velocity impact were to destroy a satellite, suddenly instead of having one large satellite, we have thousands and millions of pieces of small debris all traveling at high speeds that could cause an even bigger problem. So, legally tricky, physically tricky, materially tricky. 

So this idea of active remediation though, again, is something that a lot of people are interested in trying out, but can cause problems along the way. Now, mitigation is also finding its feet in terms of being part of this innovation, the innovation trend. Several companies, and notably SpaceX, as shown in this image, in this animation here, are trying to build reusable rockets, which would mean at least one major source of debris, empty rocket bodies, would be reduced. 

And rocket bodies can be very, very dangerous, especially if they still have fuel in them, they can explode, cause more shards of debris to crowd orbit. So there's lots of different ways that different organizations, even private companies are trying to address the space debris problem.

Now, I want to wrap up by thinking a little bit, again, about not only about space junk itself, but how space junk can be tricky in terms of its definition over time. So I've shown you a few different moments in space history that I've kind of categorized as being moments related to space junk and the creation of debris in space. 

So this image here, this jet bag, is it space junk or is it space treasure? Now, there could very well be human feces in that bag, I'm not sure, so you could argue that yes, it's a piece of junk. It was left behind purposely by the astronauts because they no longer wanted it, it no longer served a purpose. But if you think about it, this whole site is a heritage site. 

It's something that has a lot of cultural value to people around the world, something that has a lot of value that if it were to be disturbed or destroyed, we would all feel a loss.

Is this, are these dipoles space junk or space treasure? Well, to those who needed a way to keep the lines of communication open during the Cold War, this was very, very valuable space infrastructure. For astronomers, it was dangerous space junk.

This is a piece of debris that fell into South Africa in 2000. This is a piece of a rocket. It's a gas canister.

Is this space junk or space treasure? Well, a piece of space junk fell in the same country years earlier. A piece of John Glenn's rocket fell in South Africa, and a piece of it, this was in 1962, and a piece of it ended up being returned to the government as an artifact of goodwill, kind of a cultural exchange. So even this kind of seemingly obvious piece of space junk, it still had value when value was applied to it in that particular geopolitical context.

This is the Hubble Space Telescope. It will eventually stop functioning, and now that the space shuttle can't go up and retrieve it, it will remain in orbit until it no longer, until it succumbs to gravity and friction and reenters the atmosphere and is destroyed. Now, I assume most of you out there are also space nerds, that's why you're here, and it hurts in a very deep place to think that the Hubble Space Telescope will be destroyed. 

But it eventually will have to be because there's no way to boost it into a higher orbit, like we used to be able to do with a space shuttle So, but I don't think any of us will argue that this his space junk. Even when it stops functioning, it's still something that has a lot of meaning for those of us on the ground, for us on the ground. 

So I want to leave you with these ideas, again, of thinking about how space junk itself, even defining space junk can be incredibly tricky, both legally and on a personal basis, on a cultural basis. That the things we throw out, whether on Earth or in space can have different meanings for different people at different places in time. And with that, thank you, and I would love to hear your questions. 
(audience applauds)