Daniel and Kelly’s Extraordinary Universe - How do you navigate in deep space?

Episode Date: June 9, 2020

Daniel and Jorge talk about a potential new GPS: the Galactic Positioning System. Learn more about your ad-choices at https://www.iheartpodcastnetwork.comSee omnystudio.com/listener for privacy information.

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But, no, mostly I couldn't live without the directions. Right, yeah. Are you the kind of driver that needs to check the map every 10 seconds? Oh yeah, that is me. I like to know exactly where I am on the surface of the earth. At all times, huh? At all times. I need constant updates to make sure I've not gone off course.

Well, what are you going to do when humans get out into space? Are you going to get around there? I'm just going to wait until there are enough cell towers. Or at least Wi-Fi? Yeah, basic human survival needs in space. Air, food, and Wi-Fi. Hi, I'm Jorge. I'm a cartoonist and the creator of PhD comics. Hi, I'm Daniel. I'm a particle physicist, and I plan to be the one millionth person in space.

The one million. You know, there are seven billion of us, so that's pretty far ahead in line. Yeah, well, I don't want to be the first person or the second person or the hundredth person. But I also don't want to be the last person. You know, I want to go when it's still kind of new and fresh, but not dangerous. I'm not a test pilot kind of a person. I see. So a million sounds about right. Million sounds about right.

But, hey, I'm flexible. Two million, million and a half. You know, I'm not going to elbow my way in that line. Well, welcome to our podcast where you are first in line to hear this. It's called Daniel and Jorge Explain the Universe, the production of IHeart Radio. Where normally we take you on a mental trip around the cosmos, zooming out from the tiniest little particles that define the basic building blocks of the universe all the way out to the grandest structures that shape the nature of the cosmos itself. Yeah, just think of us as your guides, as your personal GPS to all of the amazing and wonderful things that are in the universe and also all of the unknown things that are out there for us to discover. Do you think we're a good mental GPS? Sometimes we get lost. We get on a discussion about neutrinos.

and we end up talking about snack foods or something else. Well, you know, I think detours are part of the fun of a trip, right? I wish that my navigation, like Siri would tell me like, hey, pull over and get some chips. There's a good snack shop right here. Why not? Yeah, that should be a setting, right? Suggest snacks. I like that. Suggest, yeah. AI engineers get on it.

Not in a hurry. It should be maybe an option. Open to wonderful discoveries. That's right. And on this podcast, we try to open your mind to all the future wonderful discoveries that science will bring us. And we do that by talking about the cutting edge of science. All the questions that science has not answered, all the things scientists are trying to figure out and all the technical problems they are trying to solve

on their journey to give us the answers. Yeah, because I think sometimes the thing about a journey of discovery is the journey itself, you know? And the friends you make along the way. Oh, yeah, you know, not just where you go and what you find when you get there, but also how do you get there? And how do you even know where to go when you're going?

Yeah, I think people imagine that it's hard to get to Jupiter or Pluto because it's so far out there. It's just like you've got to throw a rock really far into space. But it's not just really far away. It's like a very hard to find. You know, Pluto is a small rock in the vast, vast reaches of space. If you're going to throw something in that direction, you have to be really precise. You have to really know how to aim it and it has to be able to course correct along the way. And that turns out to be not so easy.

It's much harder than stopping for snacks. Yeah, you know, they have good snacks in Jupiter. You know, it makes you a little gassy at the end, but, you know, it's all totally worth it. Right, right, the Red Storm Chips. I love those. Yeah, so today we're going to be asking a question that I personally have had a lot of curiosity about over the years. I've always wondered about this question. And even more so now recently that I've been rewatching all the Star Wars movies.

And so this is a question that's really present in my mind that I've been asking. I'm asking myself recently. And why is that? Are you imagining how you're going to navigate to your in-laws house on the Jovian moons from your vacation place in Saturn? Or what inspires you to think about this? Well, my wife and I are immigrants,

but we're not that kind of alien. But no, I just kind of wonder, you know, in Star Wars, they always get lost or they pop up in all kinds of places. And so how do you know where you are and how do you know where to go? Or, you know, they talk about like a map of the galaxy. What does that even look like?

or how would that even be useful? Yeah, it's very rare that they're like, make a wrong turn. They're like, were we supposed to turn left at that pulsar or right? I don't even really remember. It feels like that's all just sort of been integrated into the electronics they have in front of them. But those are hard problems, right? It's not necessarily trivial to figure out. Yeah, and if you think about it, in popular culture,

there's only been like one TV show about getting lost in space. You mean? It was called lost in space. You know, at least you know what it's about. Yeah, so today on the program, we'll be asking the question. question. How do you navigate in space? Space, space.

And this is a problem that's relevant to future navigation. Like imagine, you are flying a spaceship with lots of people on board and trying to get everybody safely to Alpha Centauri. And it's also a question today as NASA and the ESA launched satellites to explore our solar system. How do they make sure they get to the right spot? How do they course correct if they are off? Who does those calculations? Is it on board the satellite or back here on Earth? Are there people with protractors and pencils scribbling things furiously?

How does that actually work? Yeah, because you know, space is pretty big and it's three-dimensional, you know? At least three-dimensional. At least that we know of that we think about right now. But it's multidimensional and you're out there and, you know, there's no mountain to reference, no street signs. How do you get around? How do you know where to go? think that third dimension is going to lead to like a lot more marital arguments in the

future like I told you to turn up at that moon. Oh man. Why did you turn down? This is like so many more ways to go. It's a whole new dimension to divorces probably. No, but it is really hard and it's also vital because you're so much further away from your resources. Like these spaceships, they leave Earth. They're never getting a refill. Like they run out of gas because they got lost. They're just lost. So you have like a very limited window to. To make the moves you need to make, to enter that orbit or to fly by the moon, there's no redos. You have one tank and that's it. So it's absolutely critical that you don't get lost and that you figure out how to get where you need to go.

Yeah. So as usual, we were wondering how many people out there had thought about this question or even have an idea about how to navigate in space. So as usual, Daniel went out there and asked the internet to try to answer this question, how do you navigate in space? That's right. And if you'd like to participate in our virtual person on the street interviews, just shoot us an email to questions at danielanhorpe.com. We would love to put your uninformed speculation on the podcast. And so think about it for a second.

If you were out in space in the middle of the galaxy or in between galaxies, how would you know which way to make your way home? Here's what people had to say. Because gravity distorts space and time and everything, maybe you'd have to go, maybe you'd have to shoot a little bit off it because as you go close to an object, you'd kind of be taken into its gravitational swing. Other than that, I don't know, how do you navigate through deep space? Do you just keep a set of stars to your left and hopefully you're going the same direction? I have no idea. Maybe by extracting energy from the sun or if we're very patient,

and maybe with solar sails, we could navigate deep space. Maybe through a pulse of a star, or like, I don't know, pulsars or something. I think the only way you can navigate in deep space is the way we do it now by using stars and galaxies, things that are consistent. Not necessarily constellations, because that could, you know, in 3D space, they have depth and they have angles that they are relative to each other, you know, constellations do. But if we use stuff like pulsars and quasars and, you know, the Andromeda Galaxy, those things we can coordinate ourselves, using a couple of those angles, we can coordinate ourselves in deep space, I think.

Navigating in deep space, I'd imagine, would still need the basic rules of navigation. You'd either use inertial navigation, setting time, speed, and direction from some initial stuff. You'll have to pick something like the sun and navigate in reference to the sun. Let's say if we are heading to a prime centauri, we should at least have to. an in-built special IR and visible telescopes, I mean, lens and mirrors, and special lasers, and optimal path correction systems, and some kind of special clocks. Navigating in deep space, I would have to assume, is much like sailing the ocean. You look at the stars and see where you're at relative to the stars.

After your statement that space is expanding faster than the speed of light or faster than light can travel through it, I really have no idea now. I think you could go anywhere you go. Yeah, well, hopefully you can do that. But how you do it, my idea would be to mount a big giant telescope on the top of your spacecraft on the front. and the back so you can see where you're going and where you came from. Maybe a telescope is big as Hubble because your spacecraft's going to have to be that big.

After we leave the planet and learn about the further stars that we don't see on Earth, we can pick three stars and by keeping track of the distance between us and the stars, we can know our position. And when the stars are too far away,

we can always pick three new stars. that we found out about along the way in our journey. So there are a lot of ideas there. What do you think of those? Pretty good, pretty good. I feel like people were sort of thinking about triangulation and using the stars somehow to tell where you are.

I feel like that's a pretty common idea in science fiction movies and books. It's like, oh, you just look at the stars around you and you know where you are and you know where to go. Or like if you look at the stars and you don't recognize things, then you're kind of in trouble. I like the guy who said, let's put a huge telescope on the front. and on the back of your spaceship, because I want that anyway. Like, if I'm flying through space, I want a big telescope because I want to see what stuff's around me.

You know, I want to do some sightseeing when I'm out there. But why do you need one in the back, though, just to see the faces of people that you leave behind? Well, because, I mean, I guess you could turn your telescope. Maybe you're saying you'll need one telescope plus like a mount or something. But, hey, more telescopes are better. Well, I feel like that is sort of a common thing is to look at the stars around you and somehow use that to orient yourself.

You know, kind of like we used the north star for a long time to kind of tell which way it was north when you're out in the middle of the ocean. Is that kind of an idea that we can use at all? It is an idea that we can use. And it rests on this notion that if you have an accurate map of the stars, you can compare that to what you're seeing and look for landmarks and try to measure angles between the stars to give you a sense for where you are. For example, if two stars are almost lined up in your vision,

then that tells you that you're a long, line drawn between those two stars. And if you can find other examples measuring angles between stars, you can give you sort of a point in 3D space for where you are at that moment. Well, I guess the problem that I've always sort of thought about is like, what if you find yourself on the other side of the galaxy? How would you even recognize any of the stars? Because the stars are going to look totally different from the other side of the galaxy.

Yeah. If you just look at it, like, teleported to a random place in the universe where you have no reference points, there's literally no way to know where you are because there's no absolute reference. There's no like point in space that's defined at zero and you can measure your location relative to that. If you get teleported to an arbitrary point in space, special relativity says it's impossible to know where you are. You can only measure your distance relative to other stuff. So if you have no familiar references, you're totally screwed. Wow. And things are like changing in time also? Everything's moving. So you're sort of totally lost in? You're totally lost. Yeah. The

only way to orient yourself in space is relative to known things. Wow. So if you get teleported to some part of space that's totally unfamiliar, then you literally have no way to find your way back except for randomly exploring until you do find a landmark. I'm going to try that the next time I get lost and my spouse is complaining. I'm like, it's special relativity. It's a law of the universe. It's not my fault.

Daniel said this should work. Don't you feel like smartphones must have solved this marital complaint? Right. Spouses don't have to argue about how they're navigating anymore. They just listen to the phone. That's right. The phone has saved a lot of marriages probably. Maybe.

Or maybe people are like, no, listen to my phone. Well, my phone says it's faster to take the expressway. You're using Google Maps. No way. Why aren't you using ways? People who argue are going to argue anyway. I guess so. I guess phones can't fix that.

Yeah. And, you know, navigators throughout history have used the stars. Like if you have sailed the oceans, then to figure out where you all. are in this vast sea where you can see no landmarks is just to look up and look for star marks, right? To look for positions of stars in the sky that gives you a sense for where you might be. All right. Well, let's get into the sort of the nitty-gritty of this problem.

And because I know you've told me that there are sort of several ways in which we can right now sort of calculate where we are in space, you know, barring kind of like a complete map of the entire galaxy. So step us through. What's the sort of the basic way that we get around in space? So the simplest way and the dumbest way and the worst way is basically dead reckoning. And that says you know where you started, right? You started on Earth.

And if you have a record of all the moves you took, you went in this direction at this velocity, you should be able to calculate where you went because, you know, spacecraft followed the laws of physics. And we know what those laws are. We have a whole model of the solar system. So we should be able to predict if you leave in this direction at this time and you fire your rockets here and, there, we should be able to predict where you end up.

That's kind of like closing your eyes and like knowing where you are right now, closing your eyes and just by like counting your steps and how you think you turn, sort of like making it to your fridge or something like that. Yeah, it's like following one of those treasure maps, like 15 paces forward, then turn left, step four paces, then dig, right? Right. And that's a little terrifying. Like if you remember the days before smartphones where people had to like actually write

down directions and there were things like, drive for 15 miles. then take a left. Right. And you had no idea, is this the correct left or not, you know? Yeah. Yeah, and we all know how well that works in the middle of the night when you have to go to the bathroom in total darkness, you know. You better put your hands in front of you just in case.

Yeah, and so sailors used to call this dead reckoning. And, you know, it's not terrible. Like, it works okay. We have a pretty good model of the solar system. And we have rockets and we can even measure. We don't even have to just guess at, like, the effect of thrust. You can measure how much you've experienced. accelerated using accelerometers.

You can measure the direction that you ended up in using gyroscopes. So we've tried to be really careful about this. And some spacecraft in the history of American exploration have used dead reckoning. But I guess it's tricky too because in space you can't count your steps. Like there's nothing to hold on to tell you how far you move. You have to measure your acceleration and then integrate that to convert that to velocity and then integrate that to convert that to distance. So it's like a lot of room there to get errors.

Yes, and you mentioned a very critical step there, which is integration, and that requires knowing the time. You can't count your steps. What you need is a very accurate clock. And the more accurate your clock, the more accurately you can calculate how far you've gone. Right. So if you said, I shot off in this direction at this speed, well, did you go for 2.7 seconds or 2.8 seconds? When you're traveling at 10,000 kilometers per second, that makes a big difference.

Yeah. And when distances are so huge, right? And the stakes are so high. Like, you can't, if you miss Jupiter by a few miles, it could be bad news. Yeah, if you're going to do a Jupiter drive-by, right, then you only get one shot at it literally. Right. And so it's pretty tricky. And the problem here is that errors build up.

Like, you make a little mistake because you turned a little too far, then you're off. And the next time you can't correct it. And so the errors just build up and they integrate. And eventually you can be pretty far from where you thought you were. Right. It literally is like walking around with your eye. eyes closed. Yeah, exactly.

So that's the most basic strategy. Okay. And you can make that more sophisticated by doing corrections. You can say, well, I'm going to use dead reckoning, plus I'm going to look at the stars and I'm going to try to figure out if I'm off. And this is what like a lot of astronauts did like Apollo 11, Apollo 13. They flew to the moon by dead reckoning. But occasionally they would check in and they would look at the stars and try to get a more precise measurement for where they were. and they would use that to correct their flight path.

Really? So I guess two questions. One is, why didn't they just use the moon as a reference? Because they were flying towards it. And they could tell if they were going away from it or towards it. And the size of it, too, wouldn't it tell you sort of the distance? And then my second question was, you know, can you actually use the stars to tell where you are? You can. So, yes, they were pointed at the moon, but that's pretty rough, right?

And what you want to do was get to the moon and then enter into orbit around the moon. And that was a very precise maneuver. And just like with the spacecraft, they had a limited amount of fuel. So if they burnt their fuel the wrong time, they might not be able to make it home. Oh, I see. And fuel is very expensive to lift off the surface of the earth. And so everything was a very tight budget. So they had to be really precise.

There are no Ui's. Exactly. You can't just pull a Ui in space. That costs a lot of energy to pull a Ui. Like you missed the snack shop. You missed the snack shop, man. You are not going back. And yes, they did stellar navigation.

and they looked by eye to find stars and they measured the declination using gyroscopes and they used that to correct their calculations. A huge fraction of the time they actually spent in that module was typing data into that computer. Wow. Yeah, it's a complicated system. And remember, the whole program was loaded into the computer

before it launched. You didn't have guys up there like, you know, tip-tapping, editing the program being like, I think we might change the flight path or something. They had it all built in with the opportunity for small corrections based on looking at those stars. So what do you mean declination,

like where the constellation was relative to the Earth or something like that? No, relative to them, right? They had an idea for where they were and they had an idea for if we are here, the star should appear at this angle relative to the spaceship. And then they would measure

where is the star relative to where the spaceship is pointing because they had careful gyroscopes. Interesting. And those angles help them figure out exactly where they are. All right. Well, that sounds like it worked because they got to the moon a few times,

so I can't argue with that. All right, well, let's get into some of the other ways that we can navigate in space and whether or not they could help us explore the furthest reaches of the cosmos. But first, let's take a quick break. A foot washed up a shoe with some bones in it. They had no idea who it was.

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Listen to the new season of Grasasas Come Again as part of My Cultura Podcast Network on the IHart Radio app, Apple Podcasts, or wherever. you get your podcast. All right, Diner, we're talking about navigating in space. Space, space, space. You know, I just wonder why there's always an echo when people talk about space, because there's no echoes in space. It's because it's cool, man. It's so cool, cool, cool, cool.

It makes it sound mysterious. It gives you a sense of literally space. right echoes give you a sense of big emptiness but you know that's just the um audio version of the artistic impression which you know i'm not a fan of the echoes in space no i'm a fan of realistic science fiction and should give us a sense for what it's actually like to be out there though maybe you know if you're in a tiny little metal box maybe there are actually a lot of echoes but inside i see well we're talking about how to navigating space which is a big question you know I feel like, you know, whenever you watch a movie like Star Wars, it's like, how are they getting around?

How do they know where to go? And so we talked about it one way, which is dead reckoning. Like, if you know you're on Earth and you leave Earth, you can sort of track your progress. But then you also have to kind of correct your errors as you go. That's right. And a better way to do that is not just be based on your initial calculation from Earth, but take inspiration from how your smartphone gets you to your friend's house, which is that it gets messages from satellites. Here on Earth, we have the GPS system. which is constantly broadcasting messages that's giving your phone an idea for where it is.

And your phone figures out where it is by hearing these messages and knowing how long it took the message to get here from the satellite and it uses that to figure out where the phone is. Right. And it also uses like a map. Like your phone knows where all the satellites should be at any time. So once it gets a signal, it sort of knows where it is. Yeah, precisely. It knows where the satellites are. And then it gets these messages and the messages have a little timestamp on them. They say, I sent this message at exactly this time. And if you get this message, you know, 17 milliseconds later, then you know how far the message flew because you knew it flew at the speed of light.

And you get enough of these things and you can figure out where you are. I see. And there's an analogous system, there's GPS for deep space. There is. There's a space GPS. Yeah. There's a space GPS. And it's called the Deep Space Network and NASA runs it.

And it basically sends messages out in deep space from three locations. on the Earth. And satellites get those messages, send them back, and then we can use that to figure out where the satellite is. Oh, it's like a reverse. What, are you serious? It's like a reverse GPS. It's like a reverse GPS.

Yeah. What happens is you send a message to a satellite, and then it comes back, and you count, well, how long did it take for the message to go there and come back? And that gives you a sense for the distance. And then when the message comes back, it's a little bit Doppler shifted based on the speed of the satellite. And that tells you how fast this satellite is moving away from you. So it gives you a measure of the current position and the velocity of the satellite.

But I guess that only works for satellites, right? Like it doesn't work if I'm in Jupiter or does it? Well, it works for anybody that can receive these deep space messages and send them back. So it doesn't give you your position relative to Jupiter. No, it only gives you your position and velocity relative to Earth. Right. But if you know where Earth is, would this signal help you know where you know where you are in this solar system?

No, because you can't actually do the calculation yourself. And that's one problem with this deep space network is that only Earth gets to figure it out. Earth gets your message. And then the second link gives Earth the information about where you are. And then the folks on Earth have to calculate, okay, turns out you were in this position

and send it to you. So it's kind of a lot of back and forth. It's not like you can just get this message from the deep space network and figure it out yourself the way your phone can from GPS. GPS is one directional, right? because it comes with these time stamps.

Right. So why couldn't this work the same way? The reason is the clock. The clock on the satellite is not very good because really accurate clocks are necessary to do these calculations because it's much more important to be super accurate, more important than your phone's GPS. And the clocks that are on the satellites are not good enough to do this.

So they have to do the calculation back on Earth and then send it to the satellite because on Earth they have these super precise atomic clocks that keep everything in lockstep. Interesting. All right. So we can't rely on the Earth to tell us where we are. Like if I'm out in space, or can we?

Can we rely on Earth to tell me where I am? Earth can figure out where you are, how far you are from the Earth, and how fast you're going. But, you know, it's kind of limited. Like, they can get really precise measurements of where you are up to about one meter, which is really pretty amazing. Like, you're out, you know, Jupiter distance, and Earth can measure how far away you are to within one meter. Well, based on the bounds of the echo,

like the signal coming back and going there and back? Yeah, just timing the echo, because they have really precise atomic clocks. But what they can't do is figure out where you are laterally, like your angle, because there they don't have an echo measurement, right? And so there the uncertainty is more like four kilometers for every AU,

the distance between the Earth and the Sun. Oh, I see. Because, you know, if we're out by Jupiter, we don't shine like a star. That's right. Right? Like we're not visible to the Earth. So they have no idea where we are.

They just know kind of how far we are. They know how far you are and they figure out where you are laterally, basically using dead reckoning and then correcting using these radial measurements. Oh, man. But, you know, that's a pretty big uncertainty. If you get out to like the distance of Pluto, then their uncertainty is 200 kilometers. What? Which is really big if you're trying to enter into the orbit of Pluto.

Yeah. Yeah. That sounds like a pretty big error. If you were off by 200 kilometers in your phone GPS, you'd be in a whole different state. Yeah, and so practically what these folks do is they use landmarks in the solar system to correct. So if you're getting near Jupiter,

it's not like, okay, I see where Jupiter is. It can compare it to where it thought Jupiter should be, and it can use that to correct. So you're like, you're getting landmarks. You're like, oh, you're driving your friend's house. It's supposed to be a hill there. Oops, I must be in the wrong spot. I'm passing to McDonald's.

I know I'm halfway there. kind of thing? Yeah, and so cameras on board can give accurate measurements of nearby objects, not very far away, only very nearby. You see a big well-known asteroid,

you pass a moon or a planet, then you can correct. You're no longer reliant on the messages from Earth. Interesting, but the satellite does that calculation or like it has to send the picture back and then here on Earth, we're like, oh, it just passed Jupiter, this is where you are.

Yeah, that's all done on Earth currently. Sends the data back, and then we can get corrections. All right. And that's one of the problems is that a lot of this stuff relies on calculations done on Earth, and then these back and forth communications

with the Deep Space Network, which tie up the Deep Space Network. You're only talking to one satellite. All the other ones are waiting. So you can only talk to a few of them at a time. And that's pretty serious, because GPS doesn't work that way. GPS just sends out its messages

and all the phones in the world just kind of listen. It doesn't have to be bothered by the fact that I'm using it and somebody else is using it at the same time. But Deep Space Network gets tied up every time a satellite needs to figure out its position. So they have a new idea for how to improve this so that it can be more like GPS. I see. How does that work?

Just put more clocks in it? Yes, build a really precise clock and put it on the satellite. The most precise clocks we have are atomic clocks. These are clocks that measure little atoms doing very precise wiggles. They're like vibrated a very specific frequency. One of the most precise things in the universe because it just happens over and over and over again. exactly the same time step. But these atomic clocks, they're expensive and they're big. And so the reason that we don't have good clocks on satellites is because nobody's ever miniaturized them before.

So NASA spent a lot of time building a deep space atomic clock, basically a miniaturized version of an atomic clock you can put on the satellite. And is it a lot smaller? Yeah, it's a lot smaller and it's a lot cheaper. And it's about the size of a toaster. Wow. So you wouldn't want to wear this atomic clock. It's not ready for wristwatch use yes. If you want to be super on time to meetings and podcast recordings, could wear an

atomic clock, but it might be a little inconvenient. No, and these atomic clocks cost, you know, now $50,000 to $100,000, which amazingly is actually cheaper than some wrist watches you can buy for wear it. I never understood that, but some people spend a ridiculous amount. Like gold-plated iPhones, right? Yeah, well, I spent a few

years in Switzerland where they have these ridiculous watch shops you can go in and spend $200,000 on a fancy watch. But it's like hand-built with all these little levers and gears in there by, you know, dwarves underground or something. I don't know. And it's not even as accurate as a toaster. No, exactly.

Exactly. I'll take a toaster-sized atomic watch from my wrist any day. Any day. But the idea there is if you have this atomic clock on the satellite, then it can get messages from the deep space network that have timestamps on them that say, we sent this message at whatever time. and they can just compare that to its atomic clock. And it's say, oh, it took X seconds to get here.

I can figure out where I am myself. And that's a big step forward in what they call autonomous satellite navigation, where the satellites are just sort of driving themselves. Right. Then it's more like the GPS we have in our phones. Yeah, exactly. And it can just be sort of passive. The folks at home don't have to do these calculations themselves

and updated to the satellite, so there are fewer links. Right. Because the deep space network is kind of sort of overburdened right now. It's got like too many things to do. It's being time-slice between too many projects. So this would really free it up. All right. Well, it sounds like things are looking good for navigating within the solar system.

So we're getting better clocks on these satellites and spacecraft. And we're also, we can also use familiar landmarks like Jupiter or other planets or the sun to sort of orient where we are within the solar system. That's right. But then it sort of gets trickier once we get out into space, right? Yeah. All these things still rely on being able to contact. Earth. You're getting these messages

from the Deep Space Network, which is on Earth. And if you wanted to navigate to like Alpha Centauri or halfway across the galaxy, you don't want to be getting messages from Earth. They're going to be way too faint. You're not going to be able to pick them up. So you need a broader system. You need a galaxy spanning system

in order to get you out of the solar system and still make it to McDonald's. We need like a capital GPS, galactic positioning system. All right, well, let's get into how you would actually navigate if you wanted to venture out from the solar system or even go to another galaxy. But first, let's take a quick break. Your entire identity has been fabricated. Your beloved brother goes missing without a trace. You discover the depths of your mother's illness, the way it has echoed and

reverberated throughout your life, impacting your very legacy. Hi, I'm Danny Shapiro. And these are just a few of the profound and powerful stories I'll be mining on our 12th season of Family Secrets. With over 37 million downloads, we continue to be moved and inspired by our guests and their courageously told stories. I can't wait to share 10 powerful new episodes with you, stories of tangled up identities, concealed truths,

and the way in which family secrets almost always need to be told. I hope you'll join me and my extraordinary guests for this new season of Family Secrets. Listen to Family Secrets Season 12 on the IHeart Radio app, Apple Podcasts, or wherever you get your podcasts. Hola, it's Honey German, and my podcast, Grasias Come Again, is back. This season, we're going even deeper into the world of music and

entertainment with raw and honest conversations with some of your favorite Latin artists and celebrities. You didn't have to audition? No, I didn't audition. I haven't auditioned in, like, over 25 years. Oh, wow. That's a real genius. You talk right there.

Oh, yeah. We've got some of the biggest actors, musicians, content creators, and culture shifters sharing their real stories of failure and success. You were destined to be a start. We talk all about what's viral and trending with a little bit of chisement, a lot of laughs, and those amazing vivras you've come to expect.

And of course, we'll explore deeper topics dealing with identity, struggles, and all the issues affecting our Latin community. You feel like you get a little white, whitewash because you have to do the code switching. I won't say whitewash because at the end of the day, you know, I'm me. Yeah. But the whole pretending and code, you know, it takes a toll on you.

Listen to the new season of Grasas Has Come Again as part of my Cultura podcast network on the Iheart radio app, Apple Podcasts, or wherever you get your podcast. I had this, like, overwhelming sensation that I had to call it right then. And I just hit call. I said, you know, hey, I'm Jacob Schick. I'm the CEO of One Tribe Foundation. And I just wanted to call on and let her know. There's a lot of people battling some of the very same things you're battling, and there is help out there. The Good Stuff podcast, Season 2, takes a deep look into One Tribe Foundation, a non-profit fighting suicide in the veteran community.

September is National Suicide Prevention Month, so join host Jacob and Ashley Schick as they bring you to the front lines of One Tribe's mission. I was married to a combat army veteran, and he actually took his own life to suicide. One Tribe saved my life twice. There's a lot of love that flows through this place, and it's sincere. Now it's a personal mission. I don't have to go to any more funerals, you know. I got blown up on a React mission. I ended up having amputation below the knee of my right leg

and a traumatic brain injury because I landed on my head. Welcome to Season 2 of the Good Stuff. Listen to the Good Stuff podcast on the IHeart Radio app, Apple Podcasts, or wherever you get your podcast. All right, Diana, we're talking about how to not get lost in space. Although that's such a fun show Is it? You like that show? The new one or the old one? I like the old one, but the new one's fun.

Watch it with the whole family. Because, you know, it's a bit of a family adventure, some family tension there, you know? Do we leave somebody behind? If you were frozen underwater on some alien moon, would your family stop and save you or not? Oh, man. To me, it was almost too much family drama. I'm like, where's the space and they're getting lost in space? They're like melting ice.

Yeah, exactly. I thought it was good. Anyway, it's a lot of fun. Anyway, so, yeah, it's a problem. If you go out into space, especially in another part of the galaxy where the stars are in a totally different arrangement, how do you get around?

How do you know where you are and how do you know where to go? So what can we do then, Daniel? Yeah, well, what you need is some other source of signals. You either have a very accurate galactic map of where all the stars are. But as you say, these things are changing in time, and we have only measurements from Earth,

and those positions are not that accurate. What you really need is some sort of network of signals from all over the galaxy sending you time-stamped messages. I mean, if you could design it yourself, you would have a bunch of sources around the galaxy sending you messages saying time equals one, time equals two, time equals three. Right. And from those. Like the GPS satellites we have now on Earth.

Yeah, you just have, if you just have GPS satellites all the way through the galaxy, super powerful, that would be enough because you could use the nearest satellites to figure out how far you are from each one. and you'd need three of them to triangulate your position in 3D space, and then you'd be golden. But that's a trillion-dollar program. Right. Could you use like galaxies to orient yourself?

Like, you know, like if I'm somewhere in the Milky Way, I could tell where the center of the Milky Way was, maybe, and I could look for other galaxies out there, and sort of can I use that to orient myself? Yeah, and you can get a rough orientation that way, right? You can tell you know where Indromeda is relative to the Milky Way, so you can spin yourself around and tell, where Indromeda is. But it's very rough. I mean, Indromeda is really far away. And so measuring

its location precisely is not that helpful. We need much more precision than you can get from just like fixing the positions of other galaxies. Yeah, that'll tell you roughly. But if you want to navigate and you want to save fuel and you want to make it with your thousand frozen human bodies to Alpha Centauri or whatever, then you've got to be more precise than that. You don't want to miss by a few million kilometers. You go to. No, you do not. And then they start to warm up. and they're, you know, expecting to land on Alpha Centauri and have breakfast and you didn't bring any croissants. And so, anyway. And so you're saying that one idea could be like to make these GPS satellites and put them all over the galaxy, but that's really expensive.

Yeah, that's ridiculous. Like we even know how to get them there, right? That's the whole problem. You're right. How would the satellites know where to go or where they are? You'd have to like... How would we know where they are? We'd have to bootstrap them somehow.

If you don't know where the satellites are, then they're not very... useful. They're like, here's a signal from some place we don't know. Thank you very much. That's useless. So what you need to do is find some naturally occurring equivalent. Something in the galaxy that operates similar to GPS

that lets you figure out where you are. And it turns out the galaxy provides. Is it alien satellites, Daniel? Are you going for the alien button? I didn't even think about the alien button. But now I am. Now I'm wondering if aliens are using our GPS system to

navigate our solar system, right? To us. Yes. If you entered a solar system that already had alien civilization and had GPS signals, then yeah, you could use it without them even noticing because it's a passive system. Right, right. Then maybe they're using us as a GPS. Exactly.

Exactly. That's the concern. But even without aliens, there are naturally occurring very regular clocks in our galaxy. Interesting. And they are called pulsars. Oh, you don't have to build them. They're already there. They are already there.

We talked on the podcast before about what happens when really massive stars collapse, that they blow up. This is a supernova. And then if there's enough stuff in the center of it in the core, but not enough to make a black hole, it can form this thing called a neutron star, which is a ridiculously dense ball of matter. It's called like the mass of the sun, but it's the size of a city. Right. It's like almost a black hole.

It's almost a black hole. Yeah. If your star was like 80 to 30 months. masses of the sun, then you're probably going to turn into a neutron star. If it was heavier, then you probably get into a black hole. But some of these neutron stars are amazing because they have a magnetic field, which is really intense. Right. And the magnetic field means that there's a huge column of radiation that spewed out from the north magnetic field and the south magnetic field. So they're like shining a really bright light of radiation in two directions in space.

Right, because the stars themselves don't shine that much, but like the, the, the, the chaos they cause around them with the magnetic field and all the stuff around them, then that is what glows and points in a particular direction. Exactly. There's no fusion happening inside a neutron star, but there's still an intense amount of other radiation produced. And the magnetic field funnels it into these tight beams. And then if the magnetic north pole is not aligned with the spinning of the star, right? If it's not perfectly aligned like on Earth, then what you get is this neutron star that's sweeping around. It's rotating, but the direct. in which its signal is beaming, keeps scanning through the galaxy. Like a galactic lighthouse, you know, like a spotlight that just spins. Just like that. Yeah, or like just like on the top of a police car, you have this rotating red light.

And it never turns out or off, but it looks to you like it's flashing. So from Earth, if you look at a pulsar, it goes on off, on off, on off, very regularly, just like a lighthouse would or a police light. And it's not actually turning on or off. It's just sort of sweeping past you. Right. So we can use these to kind of tell where we are, like as literally like lighthouses in space? Sort of like lighthouses in space.

And the reason is that they're incredibly accurate. They have about as much regularity as an atomic clock. Really? Like these little particles in very special conditions and cold climates and special laboratories are very regular. But these enormous, massive, spinning hunks of neutrons are also regular. And so they're basically like a very powerful galactic clock that's constantly descending out a pulse, like tick, tick, tick, tick, tick. Wow. Suddenly that makes a nice guy a little more stressful.

It's full of ticking clocks. But it's like crazy periods too, right? It's not like tick, tick, tick, it's like every 20 milliseconds they're shining. There's a big variety of them from radio pulsars down to x-ray pulsars. It depends, as you say, on their period. and these ones that are very fast on like 20 milliseconds, these are the best ones to use for timing. And it's hard to imagine like an enormous, super dense star

boiled down into a tiny object that spins every 20 milliseconds, right? It's like thousands and thousands of times a second. This huge thing is spinning. It's an incredible amount of energy. Yeah, it's mind-blowing. So we can use these because we know from Earth where they are. And so if you are out there in space, you could maybe find them by looking out

and then you can tell it kind of where you are because you could recognize them by what, their period? Yeah, each one has its own fingerprint because of its period and you already know where they are so you find them. You identify them, you're like, okay, this is Pulsar XJ-17 or whatever.

And then you listen to the pulses, you know, tick, tick, tick. And based on the pulses that you hear, you can tell where in the waveform you are. Now, the problem is they don't send messages like the GPS satellites, a GPS satellites say, okay, it's time equals seven, it's time equals eight. And then when it gets to you, you can compare against your own clock. You have like synchronized clocks on each side. So you can measure how long it takes the signal to get there.

That's from the GPS. Pulsars aren't as convenient. They don't have a clock built in that labels each pulse separately. So it's harder to tell exactly how long it took the pulse to get there. Right. But why do you need to know that? Couldn't you just kind of look where they are, you know, the angle to you and then use like three or four of them to kind of triangulate where you are? What you really want to know is your distance to an individual pulsar because that defines your position

on the surface of a sphere that surrounds that pulsar. Then you do it for another pulsar and then your distance is defined by where those spheres intersect. If you do it for three pulsars, then you can figure out where your distance is exactly in 3D space. You're right that you can tell roughly where you are by the angles, but

that's not precise enough. What you really want to know is the distance to these things. Really? Why is the angle not precise enough? Because these things are really, really far away, right? And so a pretty big change in the location of the pulsar relative to you corresponds to a really small change in the angle. So what you really want to know is the radial distance, not just the angle. Oh, I see.

It works if you're moving a huge distances, but it couldn't tell you by the meter where you are. Yeah. Or if you're really close to something. Like, if you're really close to Jupiter, then its angle relative to you has a lot of powerful information about your location. But if Jupiter is really far away, then that information loses value. And all these pulsars are pretty far away.

But there's actually a really cool trick to overcoming this problem of pulsars not being like GPS satellites. Just using, because Greg, because I don't have the timestamp, they just have a pulse. Yeah, so all you know is where you are on the pulse. And so say these pulses are like, you know,

a kilometer long, for example. So if you listen to a specific pulsar, then you could tell where you are within that one kilometer long pulse. You're like, oh, I'm at the top of it, or I'm at the bottom of it, or I'm the quiet part of it, or the loud part of it. That doesn't actually tell you how far you are from the pulsar. What you know is how far you are through one pulse length,

but you don't know how many more pulse lengths there are between you and the pulsar. If you know you're halfway through its pulse, then you could be half a pulse length away from the original pulsar, or you could be one and a half pulse lengths away, or 342 and a half pulse lengths away. There's an infinite number of possibilities. So instead of locating you onto a single sphere when you know the distance, it's actually giving you an infinite number of spheres,

each one one pulse length away because all of those are consistent with what you're seeing. That's not as good as GPS, but, you know, it can still work because you can do the same thing for another pulsar and get another set of spheres and then find a third pulsar and get a third set of spheres. And where those spheres intersect is the number of places that you could be, places that are consistent with the signals you're seeing. Now, that's not just one place. It's not an unique solution.

There's still a few ambiguities. There's more than one possible location that's consistent with those signals. And then you have to figure out which one is yours based on where you thought you were recently and, you know, other clues. Oh, I see. You're sort of converting the timestamp of these. pulses to like using the speed of light to kind of tell where you are in terms of space. Yeah, exactly. And you don't know exactly how far away you are from the pulsar. You know,

like I'm a certain number of beats of this pulsar's pulse away plus a little bit. You know, only that extra little bit. And so there's lots of different solutions. Lots of different possibilities for how far you might be away from one pulsar. But if you have two or three or four, then you can narrow it down. You can say, I'm a certain distance from this one, a certain distance from that one. It's a harder problem because these pulsars aren't nicely timestamped, but people have figured it out. And if you do all the mathematics, you can figure out where you are in the solar system to within five kilometers. Wow. That's pretty good. That's pretty good. That's better than the 200 from before. Yeah, exactly. It's pretty good. And it works all the way across the galaxy,

not just within our solar system. So you can be far from Earth. Even if Earth emboats and nuclear war, you can still figure out where you are. From these pulsars, are the pulsars distributed all over the galaxy? Or are we only looking at the ones around us? They're distributed across the galaxy. People have done a study and they found like 50 or 60 good X-ray pulsars that are distributed well enough across the galaxy that you could use them as reference points. Oh, wow.

And they've actually tried this. They've done it. They've built a little one and they flew it on the International Space Station and they tried it and it worked. Oh, wow. Pretty cool. All right. So it sounds like we do have a GPS for the galaxy.

We have a galactic pulsar system. We should also call it GPS. It's pretty awesome. It's pretty awesome. I love this idea of like, you know, astronomers don't get to build what they want. They just get to look out there and find stuff and use it to be clever to extract the information they need. And here's another great example of just like making do with what you have. Right.

It's almost like nature and the universe made these lighthouses and put them all over the galaxy just for us to. kind of used to get around. Yeah, probably not just for us, but it would be a cool science fiction universe where we actually visit one of these pulsars and discover, oh, they're artificial. Maybe they're part of some alien global position system. Oh, it is a lighthouse.

It didn't occur naturally. Yeah, that would be pretty awesome. That would be worth some echoes in space, space, space, space, space, space. Cool, cool, cool. All right, well, I feel a lot better now about Star Wars and about other science fiction movies and books, it sounds like

in the future, we could be using these pulsars to kind of know where we are in the galaxy and to kind of build a map of the entire place. Yeah. And as we venture out further and further beyond our solar system and try to explore other solar systems, this will be a critical way to know where we are and

hopefully how to come home. Yeah. And so future space explorers flying around with their partners and spouses can not argue about where they are getting lost, which would probably make for a messy divorce out in space. Well, they'll probably still argue, like, let's not use that Pulsar. That one's not reliable.

Everybody's using that Pulsar. You sound like your father. All right. Well, I hope that was interesting and gives you a little bit more of a sense that we kind of know where we are in the universe and the galaxy and that it would be a little bit hard to get lost in space. That's right.

And this idea of Pulsars took decades to figure out, to narrow down, to make it work and it only gives us 5 km uncertainty, probably somebody out there will have an even better idea for how to narrow down our position. So have that idea today so that it's ready for us to use in 20 or 30 years. That's right. You don't want to miss those snacks. You know, if you miss that snack by 5 kilometers, that's not good. You're not eating that day. If you learn nothing else today, remember, there are no U-turns in space. Or echoes. But there probably are snacks. All right. Thanks for joining us. See you next time.

Thanks for listening and remember that Daniel and Jorge Explain the Universe is a production of IHeartRadio. For more podcasts from IHeartRadio, visit the IHeartRadio app, Apple Podcasts, or wherever you listen to your favorite shows. Don't let biased algorithms or degree screens or exclusive professional networks or stereotypes. Don't let anything keep you from discovering the half of the workforce who are stars. Workers skilled through alternative routes rather than a bachelor's degree. It's time to tear the paper ceiling and see the stars beyond it. Find out how you can make stars part of your talent strategy at tear the paper sealing. Brought to you by opportunity at work and the ad council.

Tune in to All the Smoke Podcast, where Matt and Stacks sit down with former first lady, Michelle Obama. Folks find it hard to hate up close. And when you get to know people and you're sitting in their kitchen tables and they're talking like we're talking. You know, you hear our story, how we grew up, how I grew up. And you get a chance for people to unpack and get beyond race. All the Smoke featuring Michelle Obama. To hear this podcast and more, open your free Eye Heart Rate. app search all the smoke and listen now i'm simone boys host of the bright side podcast and on this

week's episode i'm talking to olympian world cup champion and podcast host ashlyn harris my worth is not wrapped up in how many things i've won because what i came to realize is i valued winning so much that once it was over i got the blues and i was like this is it for me it's the pursuit of greatness it's the journey it's the people, it's the failures, it's the heartache. Listen to The Bright Side on the IHeart Radio app, Apple Podcasts, or wherever you get your podcasts. This is an IHeart podcast.