IRA FLATOW: This is Science Friday. I’m Ira Flatow. Later in the hour, we’ll talk about circadian rhythms and the biology of time.

But first, last month SpaceX launched 60 satellites into low Earth orbit as part of its Starling project, which Elon Musk’s ambitious goal to provide satellite based broadband. He’ll need to launch 42,000 total satellites to complete the project. But each of those satellites is program to deorbit and burn up in the atmosphere. And unless there is a problem then, the satellites will burn up in Earth’s atmosphere within one to five years.

And you add to that the roughly 2000 satellites already in low Earth orbit, then, well, space is getting pretty crowded with our stuff. And all our stuff is creating a lot of junk. Estimates for the big pieces of trash– about 10 centimeters. That’s about the size of your palm. About 20,000 of those objects.

The real tiny stuff? Over 100 million particles floating around above our heads. How can we clean up the planet’s atmospheric attic? And what questions should we be thinking about as more and more satellites and companies are getting into the game?

My next guests are here to talk about that. Moriba Jah is an associate professor of aerospace engineering and engineering mechanics at the University of Texas at Austin. Welcome to Science Friday.

MORIBA JAH: Hey, how’s it going, brother? Good to be here.

IRA FLATOW: Nice to have you. Alice Gorman is a space archeologist, associate professor in the Humanities, Arts, and Social Sciences at Flinders University in Adelaide, South Australia. Her new book is called Dr. Space Junk versus The Universe– Archeology and the Future. Welcome to Science Friday.

ALICE GORMAN: Good to be here.

IRA FLATOW: Alice, I want to read from your book about just what is up there in space. You say, orbiting Earth, right now– satellites that work, satellites that don’t work, the rocket stages that delivered them, bolts, canisters, faring, exploded fragments, flecks of paint, shrapnel, tools, fuel, and possibly a remnant or organic waste from human spaceflight missions. Yes, I mean space poo. Is there any way to keep track of all of this, Alice?

ALICE GORMAN: Well, we have a whole range of different instruments on earth who are actively tracking many of these space objects. But they tend to be the larger ones, the ones that [INAUDIBLE] watching them all the time because, to say, lose five of them per a minute, as it were. Orbits are very non-linear and non-predictable, so things can get lost quite easily.

So there is a whole bunch of stuff that we know where it is. And there’s a whole bunch of stuff we don’t know where it is. And another millions and millions of all those tiny little things [INAUDIBLE]

So we don’t know where they are. And we need to predict and model all of this stuff to work out what the risks of collision are. And we’ve just got massive debt in the data that we have about what’s up there.

IRA FLATOW: Moriba, most low Earth satellites and decommissioned space stations are programmed to fall back to Earth and burn up, right? What is creating, then, all of this debris if those satellites are supposed to burn up?

MORIBA JAH: Yeah, so interestingly enough, I think a good way to think about this stuff is that we don’t put stuff in random orbits around the planet. We try to take advantage of mother nature, of gravity, as much as possible to spend the least amount of fuel. And as such, you can envision these kind of orbital highways in space. And they’re very specific, depending on the kind of mission you have and what you want your satellites to do.

So a lot of these satellites in low Earth orbit, even though you could just leave them by themselves, they would eventually re-enter. But it takes a long time, depending on the altitude. And I can tell you that things that are, I don’t know, about 1,000 kilometers or so above the Earth’s surface won’t be returning for several generations and even more. And so that is definitely a problem.

So this idea of, well, things are programmed to come back, things go wrong, Murphy’s law, so to speak. And you definitely need intent and purpose and, hopefully, everything working right to make that happen. But even if you try to do that, then you have to figure out how do you avoid stuff on the way down. And that’s another complicated issue.

IRA FLATOW: Yeah, let’s talk about that a little later. But let’s first talk about the mentality we have about earth orbit. I mean, it seems like we just throw things up there. And thinking about them coming down is like an afterthought, is it not?

MORIBA JAH: Well, so one of the interesting things is that I would say that is, by and large, seems to be the behavior that people have taken. At the United Nations level, there is this thing called the Office of Outer Space Activities in Vienna. And there is a committee on peaceful uses of outer space.

And in fact, this calendar year, they just passed 21 guidelines towards long term sustainability of near Earth space. But these things, in and of themselves, are not legally binding. They could be if each of the 93 countries that signed made them space law in their own country.

But then it’s like, well, how do you enforce that? What court of law do you bring stuff to? Like there’s a variety of issues and complications that follow. But implementing those would be kind of the next step.

IRA FLATOW: Alice, do you get the point I’m trying to make? And I think you make it in the book also that there’s sort of this disconnect, that this is, well, it’s not here on Earth. So it’s not really that close to us.

ALICE GORMAN: Yeah, so you think, well, usually we can’t see any of this stuff. People on earth are using all of these satellite services. But they don’t sort of think or visualize or connect to everything that’s over our heads.

And in the space science community, I think, and the space industry community, it’s pretty much like that. Like you launch your space asset to do the job it’s going to do. Once that job is done, you just don’t think about it anymore. Calling it junk means, in one sense, you can forget about it and discount it in your planning. Except, of course, as we now know, you absolutely cannot do that anymore.

IRA FLATOW: Mm-hmm, you mention in your book– and this was an interesting comment you made– you talk about when a big project happens on Earth, you put out an environmental impact statement. Do we need one for when we put something in orbit?

ALICE GORMAN: I really think we do. So at the moment, there’s a whole bunch of things people have to do to get permission to put stuff into orbit. But because we’re not really used to thinking of space as an environment– like, for most people, space is a vacuum. There’s nothing much up there. So we don’t kind of have a much broader view of what all of the factors we need to take into account are.

And the environmental management process basically involves taking into account impacts of all kinds, including social. And this is where I think we can connect with people on earth, who maybe don’t normally think about satellites, to maybe exert a bit of pressure on all of these big corporations and these big space agencies who have up until now been kind of pretty content to put stuff up there and then just forget about it. So I think those social factors that come into environmental management are actually quite important.

IRA FLATOW: Mm-hmm, well, what about– oh, I’m sorry, Moriba. Did you want to do something there?

MORIBA JAH: Yeah, a sort of thing that I wanted to follow up on that is that, interestingly enough, if you look at sustainability, I think, first and foremost, people globally need to accept that near Earth space is a finite resource. And until that happens, we can’t talk about environmental protection. So I think saying, yep, you know, outer space is probably infinite. But near Earth space is finite and back to these specific orbital highways that are getting more and more congested with traffic.

But once we can accept that you know near Earth space is a finite resource, then we can talk about environmental protection. And one of the things that I’d like to underscore, going to what Alice was saying, in terms of bringing the social peace, is that, if we look at models of sustainability on the planet, we can look no further than our indigenous people and what they’ve done to actually achieve sustainability.

If you look at the Aborigines and the Maori in New Zealand and Inuit in the Arctic, each of these indigenous peoples have, for thousands of years, developed, let’s say, a code of behavior, some norms and practices, that have allowed them to be sustainable over thousands of years in harsh environments and ecosystems of scarce resources. We should apply these tenets of so-called traditional ecological knowledge to achieve space sustainability. And this would allow people to be more inclusive and bring these sociological aspects that Alice was referring to.

IRA FLATOW: I–

ALICE GORMAN: I’d just like to follow up on a Moriba’s point there as well because I think one of the issues is, who owns space? The situation of Earth’s orbit has been called a tragedy of the commons. Space is meant to be the common heritage or province of Humanity. But in fact, very few nations and corporations sort of have control of that.

So we need some different models those of us who can have access to space and who can use it. That sort of blanket phrase, common heritage, isn’t really sufficient at the moment. And picking up on what Moriba says, there are a lot of indigenous models of resource ownership– I don’t mean ownership. Resource use or resource responsibilities for resource that I think we can also co-opt into being more creative about how we develop a sustainable long term use of space.

IRA FLATOW: Our number is 844-724-8255 if you would like to talk about this. This is a huge multicultural, multi-level problem. I know, Alice, you even talk about the value of this space so-called junk, where somebodies junk is someone else’s treasure, and actually using it as museum pieces up there.

ALICE GORMAN: Well, there’s some extraordinary objects. In that class of things that we just say, oh, you know, this is junk, there are some spacecraft that have incredible stories and that are connected to communities of people on Earth. And I don’t think enough people know about this stuff.

So I think we can look on it as not just on Earth’s orbit but not just as a, as Moriba says, a limited resource that we can use for our own ends to create situation on Earth. It’s a cultural resource as well.

The junk up there is the story of the early space age. 500 years from now, how are people going to look at some of these objects? They’re going to be like a paleolithic handex. They’re going to be these extraordinary things that are a window into the minds of the people on Earth now, who, if you think about it, we’re really only just starting to get into space.

IRA FLATOW: Alice Gorman, author of Dr. Space Junk versus the Universe– Archeology and the Future. Also, Moriba, I will come back and take your questions 844-724-8255. Also take your tweets at @scifri. So stay with us when we talk about more space junk after the break.

This is Science Friday. I’m Ira Flatow. We’re talking this hour about space junk and how to cleanup, live with it up there in low Earth orbit. The guests are Moriba Jah, associate professor of aerospace engineering and engineering mechanics at UT Austin, Alice Gorman, author of the new book. It’s called Dr. Space Junk versus the Universe– Archeology and the Future.

Our number, 844-724-8255. Let’s go to the phones to Jeffrey in Cedar Rapids, Iowa. Hi, Jeffrey.

JEFFREY: Hello.

IRA FLATOW: Hi, go ahead.

JEFFREY: Yeah, I was wondering if there’s no way to bring this more down to earth in a sense that is there website that we could go to where we could see the space junk so we could get a feeling for what kind of a mess we’re making up there, kind of to get a better hold on it.

IRA FLATOW: Good question. Alice, can you go see– is there a website to see what space junk looks like?

ALICE GORMAN: There are places you can go to see visualizations of the density of space junk and its location. So there’s some great images that NASA and ESA have. There’s also a database called Heavens-Above that you can go in and look up any satellite and see where it is at the moment.

And there are some great software things. One of them is ATK that will give you visualizations of space junk in actual motion as it’s going around the Earth. But Moriba, you have your own one of these, too, don’t you?

MORIBA JAH: Yeah, so basically, if you Google Astria– A-S-T-R-I-A, AstriaGraph, you’ll find it. And we actually have a crowdsourced database of multiple catalogs from different– from the US, from Russia, and from other people that shows all these opinions in one common framework. And it’s been up and running autonomously for over a year now. So I would definitely suggest checking that out.

IRA FLATOW: Here’s a question from Facebook. Keith asks, is there any pollution or waste created when something burns up in the Earth’s atmosphere? And if so, does the pollution stay in the Earth’s atmosphere? Or does it float off into space?

ALICE GORMAN: That’s a really great question. And in fact, some people have done studies on rocket exhaust fumes from launches and their effect on the upper atmosphere. I haven’t seen any studies on impacts of the reentry of space junk. But Moriba might be aware of some of this research.

MORIBA JAH: Yeah, I can say that as objects are getting ablated and are dissolving in the Earth’s atmosphere, certainly those particulates are part of the atmosphere constituents at those altitudes. In terms of how long does it take those things to dissipate, I’m not sure.

I think– here’s the thing, right, certainly it’s not great. I mean, if you look at the oceans and what we’ve done there, what happens if you take a one liter bottle of Coke and just dump it off to side of the ship? I mean, yes, eventually that gets diluted.

But as you can see, if you do enough of that, then there’s significant long term impact of that sort of thing. Are we there yet? Probably not. But at the same time, it’s something that we should be mindful of, for sure.

IRA FLATOW: The first thing that comes to mind when you ask people about what their reaction to this is, like I do, when they say, why can’t we just take a net up there and just collect it all?

ALICE GORMAN: [LAUGHS]

IRA FLATOW: Right, Alice? Isn’t that what people must be saying?

ALICE GORMAN: It sounds like an easy thing to do. So that’s what we do on Earth. We get some kind of garbage truck. We get containers. We gather it all up.

The problem in space is that, despite some of the visualizations you’ll see, things are actually quite far apart. And they’re moving at incredibly high speed. So you don’t want to take your garbage truck or your neck up there, have it collide with a piece of space junk, explode and create more space junk.

And at the moment, with the propulsion systems that we have, it’s actually really expensive to kind of maneuver around in orbit. You have to take all of your fuel with you. And the idea that you just sort of zip around with your net and your harpoon and catch all these things and bring them back is just not possible at this point in time.

IRA FLATOW: I think the greatest popular visualization we’ve had in recent years about what could happen in orbit with all the space junk is that movie Gravity, where the space station is just trashed, right, by collisions with space junk. Moriba, is that possible, something like that?

MORIBA JAH: Yeah, so here’s the thing, right. I mean, yes, it’s a bit of hyperbole in terms of this runaway process as accentuated as it was in the movie Gravity. But it’s not out of the realm of the possible for some sort of cataclysmic event like that to happen with the space station.

And we hope that it never comes to that. But it’s not out of the realm of the possible. And so this is something that we definitely have to be very careful of.

And interestingly enough, one of my good friends, former astronaut, Susan Helms, she was telling me that there was this module in the space station that she would go in. And she would hear these dings on the outer shell, you know, ding, ding, ding, ding. And it was fairly frequent.

And guess what that was. Space junk, whether it’s micrometeoroids or actual fragments, flecks of paint, that sort of stuff. So we know that these things exist. We know that they’re impacting different surfaces. We know that we face a tragedy of the commons unless we actually engage in sustainable behavior.

IRA FLATOW: A tweet from a Forrest who asks, what type of space junk is the most dangerous?

MORIBA JAH: [LAUGHS]

[INTERPOSING VOICES]

ALICE GORMAN: –there is actually–

MORIBA JAH: Go ahead, Alice.

ALICE GORMAN: I was just going to say there’s one object which is very dangerous, which is the NV set, which is kind of the number one old satellite on the top of everybody’s hit list. But that’s one satellite. And then there are classes of objects, which also have specific dangers.

IRA FLATOW: Let’s go to the phones to Keith in Cape Coral, Florida. Hi, Keith.

KEITH: Hello.

IRA FLATOW: Go ahead.

KEITH: I had a comment about the newly formed Space Force and how that might affect the debris in near Earth orbit? [INAUDIBLE]

MORIBA JAH: Yes.

KEITH: Putting weapons up there, any ordinance up there, or mining in space, and it has a lot of possibilities experiencing the Kessler syndrome.

MORIBA JAH: Yeah, so I guess on my end, what I can say to try to address that is the following– in terms of weaponization of space and that sort of stuff, I can tell you, having been part of the military myself and having worked for the Air Force research laboratory for a decade, nobody really wants to put weapons, as it were, in space. I think everybody agrees that that’s, in general, a really bad idea.

As far as military presence in space, look, it’s been up there since Sputnik. So the military, of not just the US but all these other nations, have been a part of space for a very long time. And I would say this, right, I mean, we have a booming space commerce landscape that is just growing by leaps and bounds.

And I would say, when people needed to cross the oceans or they needed to cross the United States from the East Coast to the West Coast, sometimes the government would provide, call it escorts, some sort of government presence to help protect the livelihood of these people going from point A to point B. My guess is– without currently working for the government, my guess is that it would make a lot of sense if the space for were analogous to the US Coast Guard, that is there to protect the interests of the citizenry and enable space commerce. So in that sense, I think it probably makes quite a bit of sense.

IRA FLATOW: One last question–

MORIBA JAH: Really quickly, regarding the whole Kessler syndrome, I have to tell you that I’m not a big fan of that concept. Everything that I’ve seen so far in nature is such that nature is always trying to seek some equilibrium state. And my guess is that, at some point things, become small enough to where it doesn’t make that much of a difference.

IRA FLATOW: I need to interrupt because we only have about a minute left. And one interesting tweet from Robin, who says, what are your thoughts on the benefits of the global satellite internet versus the drawbacks of having thousands of SpaceX satellites, obstructing our view of the celestial bodies and clogging up the Earth’s orbital highway? And Alice, your last thoughts on that.

ALICE GORMAN: Well, I’m not a fan of Starlink. Let’s just put it like that.

IRA FLATOW: OK. [LAUGHS] [INAUDIBLE] good succinct way to end it. Alice Gorman is author of the Dr. Space Junk versus the Universe– Archeology and the Future. Also Moriba Jah, associate professor of Aerospace Engineering at the University of Texas at Austin. Thank you both for taking time to be with us today.

MORIBA JAH: Thank you.

ALICE GORMAN: Thank you.

IRA FLATOW: You can read an excerpt from Dr. Gorman’s book on our website at sciencefriday.com/spacejunk.