How GPS shaped our world

[THEME MUSIC] IRA FLATOW: Hey, it’s Ira, and you’re listening to Science Friday. In early 1990, I was given a tour of the San Andreas Fault line by US Geological Survey scientist, the late great Al Lind. I was riding in his red pickup truck, and between us in the front seat was this little wooden box with little red numbers that jumped around as we drove.

So I asked Al, hey, what is this box all about? And he turns the steering wheel in different directions, and he says, look at the numbers. And I did, and these little red Nixie tube numbers danced all around as he drove.

And I said, hey, Al, what’s going on here? And he said, believe it or not, there’s this satellite overhead that is transmitting our exact location to us, our exact coordinates to this box, and the numbers change as I drive back and forth over the road. Now, I couldn’t believe it until about a year later when the Gulf War broke out and the world’s global positioning system emerged from obscurity.

No one could imagine how GPS would become such an essential part of our lives. A whole generation of people today never knew a world without it. But GPS, like many tech advancements of the 20th century, was originally created by the US military. So how did it become a routine part of civilian life, and how vulnerable is it to manipulation?

My guest, Katherine Dunn, has written all about this and more in her book, Little Blue Dot, How GPS Shaped the Modern World. Welcome to Science Friday. Thank you so much for having me. Is that a familiar-sounding story that I told?

KATHERINE DUNN: Yeah, it comes up again and again, actually, that people tend to remember the first time they encountered GPS. And the closer they were to logistics or they were hikers or they were sailors or whatever, the more explosive that moment is. And there was a lot of people who told me they saw the little box, like you, and they said, wow, OK, this is going to change everything.

IRA FLATOW: So what sparked your interest in GPS? Give us your story.

KATHERINE DUNN: I had a weird route into this, and my route was through some bad Russians, basically. I was covering oil products, how things moved around the world. And it was in 2018. So it was the year after this happened. I stumbled on an article that told the story of these ships arriving in a Russian port city called Novorossiysk, on the north edge of the Black Sea, very near Crimea, which becomes relevant.

And when these ships arrived, the alarms started blaring, saying there wasn’t really reliable GPS. And the crews looked out the window. They were at port. They knew exactly where they were. And then they looked at the screens, and it showed that they were on the tarmac at Russian airports.

IRA FLATOW: No.

KATHERINE DUNN: Yeah. So it was like a weird mystery. But I was not the only one who stumbled across this and said, wow, there’s something really weird going on here. Reality and GPS have diverged.

And it turns out for people in the GPS community, which is a small but intense community, there have been people warning that this could happen. And now this was the first time they saw it out in the wild, as it were. And it was clearly connected to the Russian government, and it was very connected to– Putin was in the area, shall we say. And that’s what got me hooked.

IRA FLATOW: What do you mean Putin was in the area? So they were hacking the GPS?

KATHERINE DUNN: So it took quite a while for them to put the pieces together. There was a young researcher called Hugh Bradshaw, and he got hooked around the same time as me. And he decided to investigate what was going on here. So one of the things he did in the ship-tracking software, he programmed it to look every time a ship showed up at an airport, was something weird going on?

But eventually, they compared it with Putin’s public schedule. Wherever Putin went, GPS behaved strangely. And eventually, what they kind of realized– and a guy called Dr. Todd Humphreys, who’s at the University of Texas at Austin, was one of the other main players unraveling this mystery. What they realized is there was a quirk here.

Commercial drones can’t go near airports, for really obvious reasons. They’d be totally disruptive and dangerous. So commercial drones were programmed so that if they got near the location of an airport, they would either drop or they would turn around.

So over time, they realized what the Russian government– they deny all of this, of course. But what seems to have happened is they would turn Putin into an airport. They would essentially geofence him so that his location registered as being at a Russian airport.

And this was to deter drones. And clearly, what they were worried about is assassinations. So wherever Putin went, this truck seems to have followed him. And it was directed at drones.

But because our world is so dependent on GPS, the boats would pick this up, the taxis would pick this up. Around the Kremlin, the same thing was happening. The taxis would all of a sudden be at the airport. And planes were picking it up. So it was in this– the real civilian world was picking up on the shadowy sort of ripples of something that was happening in a world of conflict and semiconflict.

IRA FLATOW: So how can GPS signals be manipulated so easily? What’s going on? Are there other techniques?

KATHERINE DUNN: Yeah, they can be disrupted worryingly easily. There are two main ways to do it. Obviously, anybody listening, do not do this. It is super illegal.

But the first is jamming. And jamming is the simple way. It’s just body checking the GPS signals out of the sky. So it’s exactly the same as if you ask me a question and I shout over you. You’re still talking, but I’m drowning you out. That is jamming.

And we’re talking about radio signals here. So it works the same way. But a spoofing, which is what was happening when the ship showed up at the airports, that is a hijacking. It’s a hijacking of the electromagnetic realm, in a way.

So if you’re talking, and then all of a sudden, I take over your frequency and your voice, and now I’m asking the question, that is like a spoofing. And spoofing is much harder, much more technically difficult. And for a long time, people told me the US government seemed to believe that it was too difficult to do. And unfortunately, now it’s very achievable for somebody with the right technical how a little bit of money and a willingness to break the law. So don’t do this.

IRA FLATOW: Don’t do it. What about the countermoves? Can you do that too?

KATHERINE DUNN: Well, what you see happening is this cat-and-mouse game. And for anybody who follows the war in Ukraine very closely– part of my book is about this, is about this cat-and-mouse game of, you develop a method to disrupt GPS and its other systems. There are other national systems there. And then you develop a method to counter that, or you get receivers that are more robust to this kind of interference.

Things are changing by the day. That’s how fast this cat-and-mouse game is moving of attack, counterattack, attack, counterattack.

IRA FLATOW: We have to take a quick break, but don’t go away. More on this when we come back.

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And, Katherine, we’ve talked about how it shaped the modern world so far but not how it works. I’m sure our audience wants to get into the weeds of how GPS works. So give us a thumbnail, at least, of that.

KATHERINE DUNN: Right, so the way GPS works is there’s satellites encircling the globe. There’s at least 24. There’s actually more in practice. And what it means for you– you probably have your phone sitting right beside you right now. I certainly do.

And it is within sight of, minimum, four satellites at any one time. And this four is important because four calculations are going on– so your longitude, your latitude– of course, we know that– but your altitude, so if you’re listening to this on a second-story flat or whatever, that too. And then the fourth one is time in a simple sense.

And that is the secret sauce of GPS. What it’s giving you is not just time, but it’s giving you the gift of ultra, ultra, ultra accurate time because there are atomic clocks in the satellites. And they are transmitting– basically, a super expensive clock is transmitting you time to your cheap clock in your iPhone.

And so those are working together. And the way this works, this process called trilateration, so it’s the difference between the time when the radio signal left the satellite to when it arrived, that difference, times the speed of light. It’s a very simple calculation.

1 nanosecond is equivalent to 30 centimeters, so basically the length of a standard ruler. So time and space are very, very interlinked here. So in order to do this, you’re getting time to the billionth of a second. And GPS really combines time and space in this important way.

IRA FLATOW: Timing is everything. Tell me the story of how GPS was created. You write that without the drive to bomb entire nations into oblivion, this vast system would not exist.

KATHERINE DUNN: Yeah, this is tied 100% into the story of the Second World War, but also the Cold War, the Vietnam War. The strongest sort of push came from the Vietnam War and the fact that the US Air Force had really struggled to bomb the Ho Chi Minh Trail. They had struggled to take down certain bridges. There was a real lack of precision.

And the idea here was that if you could get this bombing precision, theoretically, war would be a little bit more moral, would be more precise, and its sort of origin is usually brought back to 1973, in or around Labor Day weekend, when a group of military officials gathered at the Pentagon– there’s some controversy around this, but probably at the Pentagon. And they set out this system and what it was going to look like.

The thing to is that there were systems before this. In World War II, there were radio navigation systems for submarines and for ships and for planes. And they would all have their strengths and weaknesses. But the idea that you could use radio as a navigation tool dates from the ’30s, basically.

So they were taking this, and they were kind of combining them all into this one system to rule them all. So it came out of 1973, but the whole system wasn’t completely finished until 1995. So the time when you encountered it, the system wasn’t quite done. Even when it was used in the Gulf War, that’s probably the first time it was used in an active conflict.

But it had this really long lead time where they’re launching satellites, and the system is getting better and better and better. But yeah, you need to think of this as a product of war that we just use to order takeaway at this point.

IRA FLATOW: Tell me about Gladys West and her role. She was like a hidden figure but played a crucial role here.

KATHERINE DUNN: Yeah, she was part of this generation of Black women mathematicians that entered the Department of Defense and entered these research labs just as segregation was ending. She spent her career as a coder and trying to understand the gravitational field. And her job was really about the trajectory a ballistic missile can take from A to B and the little intricacies of the gravitational field that it will take on the way there.

Why this is important for GPS is because you’ve got all these little intricacies of the fact that the gravitational field around the Earth is not completely smooth and even. And so as a shortcut, we use mathematical models to represent the Earth. And she was one of the core people who trained those models.

People sometimes say that she invented GPS. She didn’t, but she played a really key role, as did her colleagues, in how this developed, because there was a lot of technologies converging into one when you’ve got GPS.

IRA FLATOW: How did the space race play a role in the creation of GPS?

KATHERINE DUNN: Well, the space race was really all about the satellites. So you have this race to put up the first satellite in the late ’50s. And obviously, the Soviets got there first with Sputnik. So this put the satellites up.

And once the satellites were up, the science of finding out where a satellite was in the atmosphere, in a very simple term, it was turned around and reversed, where some of the physicists working at the Applied Physics Lab at Johns Hopkins, they realized, OK, you can use the science to be on Earth, looking up the satellite, finding the satellite. What if you use the satellite to find where we are on Earth?

So it was the foundation. We often think about the space race and the drive to understand the heavens. But once we shot these things up, we kind of used them to turn around and look at ourselves, which I’m sure there’s a metaphor in there somewhere.

IRA FLATOW: Yeah, we sort of flipped it around. How did it move from military tech to being used by pretty much everyone in our smartphones?

KATHERINE DUNN: Well, it was never classified. It was always open to civilians. But it was a very particular kind of civilian. You had to know about it. You had to know how to make a receiver. It wasn’t open to the general public.

And some of the first people to do that were surveyors in the ’80s. They immediately realized this was going to make their work way, way easier. A lot of academics realized very early on, and so they started building receivers for their own purposes. One of the big pushes also to use GPS in a civilian sense was the US Coast Guard, which realized it was incredibly useful for safety applications and in ports and in harbors and all these kinds of things. And the Department of Defense, I think they weren’t super keen on letting it go.

So the US Coast Guard actually set up ways to get around some of the corrections the Department of Defense put in the signal to make it less accurate, and they really embraced it. Farmers really embraced it for precision planting. So it was all these specialists that saw. And then, of course, a commercial market emerged starting to make these civilian receivers.

One of the things I say in the book that’s quite interesting is that Japan saw the relevance really early. They saw the relevance to track the impact of earthquakes. But they also saw that they could put it in cars. So the very first car to have GPS, kind of in the way we think of it now, were these experimental kind of supercars that were appearing at the Tokyo Motor Show in 1989.

But you also find it in places like the airport in Fiji– they realized right away that, oh, wow, this is great, or Qantas, the Australian airline. So people just picked up on it, and it kind of burst out of the military world as people realized how much you could do with it.

IRA FLATOW: You write that one of the most persistent misunderstandings about GPS, especially about its use in mobile phones, is that it makes you trackable. So you say the system has no idea where or who its users are. I think a lot of people would find that really surprising.

KATHERINE DUNN: Yeah, the thing to know about GPS is that it is a one-way system. These radio signals are just raining down on you. It’s a lot like if you listen to this show on a radio, the radio station doesn’t know who’s listening on the other end. It’s one way.

Why this can feel confusing is because in reality, we use GPS as one part of a two-way system. We take the information about where we are, and we transmit out our location once we have it. And modern technology, and even ships and planes, they have this transmitting aspect where, once you have your location, you transmit it out.

IRA FLATOW: Wow. That’s more comforting to know.

KATHERINE DUNN: [CHUCKLES]

IRA FLATOW: One last question– has writing this book made you think any differently about how we as humans navigate through the world?

KATHERINE DUNN: Yes, it definitely has. And I found it so fascinating, this idea that our Earth is always changing, and it’s so hard to truly know it in this way, to pin it down with complete, utter accuracy. And I found that really, really interesting and touching that it’s really hard to truly know our own planet.

IRA FLATOW: Katherine, it’s a fantastic book. Thank you for writing it.

KATHERINE DUNN: Oh, thank you so much for reading it.

IRA FLATOW: Katherine Dunn, author of Little Blue Dot, How GPS Shaped the Modern World. This episode was produced by Shoshannah Buxbaum. And if you have any questions or comments, please give us a call, 877-4-SCIFRI. That’s 877, the number 4, SCIFRI. We always love to hear from you. Thanks for listening. I’m Ira Flatow.

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