WEBVTT - How do you navigate in deep space? 0:00:08.360 --> 0:00:12.480 Hey, Daniel, do you remember the days before we had smartphones? 0:00:13.440 --> 0:00:15.920 I try not to think about it too much. Well, 0:00:15.920 --> 0:00:19.000 you can't live with that, Wikipedia do your fingertips? How 0:00:19.040 --> 0:00:21.160 else would I seem like an expert on anything? But no, 0:00:21.320 --> 0:00:24.840 mostly I couldn't live without the direction right. Yeah. Are 0:00:24.880 --> 0:00:26.640 you the kind of driver that needs to check them 0:00:26.640 --> 0:00:29.120 out every ten seconds? Oh? Yeah, that is me. I 0:00:29.200 --> 0:00:32.120 like to know exactly where I am on the surface 0:00:32.159 --> 0:00:34.600 of the air at all times. At all times, I 0:00:34.640 --> 0:00:37.600 need constant updates to make sure I've not gone off. Well, 0:00:37.600 --> 0:00:40.320 what are you gonna do when humans get out into space? 0:00:40.600 --> 0:00:42.760 Are you gonna get around there? I'm just gonna wait 0:00:42.840 --> 0:00:46.320 until there are enough cell towers or at least WiFi. Yeah, 0:00:46.920 --> 0:01:06.959 basic human survival needs in space, air, food, and WiFi. Hi. 0:01:07.000 --> 0:01:10.360 I'm Jorge. I'm a cartoonist and the creator of PhD comments. Hi. 0:01:10.480 --> 0:01:14.480 I'm Daniel. I'm a particle physicist, and I plan to 0:01:14.520 --> 0:01:19.960 be the one million person in space. One million there. 0:01:20.000 --> 0:01:21.800 You know there are seven billion of those, so you 0:01:21.840 --> 0:01:24.440 know you let's put it pretty far ahead in line. Yeah. Well, 0:01:24.440 --> 0:01:26.360 I don't want to be the first person, or the 0:01:26.400 --> 0:01:29.160 second person or the hundredth person, but I also don't 0:01:29.160 --> 0:01:30.440 want to be the last person. You don't want to 0:01:30.440 --> 0:01:32.720 go when it's still kind of new and fresh but 0:01:32.800 --> 0:01:35.160 not dangerous. I'm not a test pilot kind of a person. 0:01:35.680 --> 0:01:38.200 A million sounds about right. A million sounds about right, 0:01:38.240 --> 0:01:40.720 but hey, I'm flexible two million, million and a half. 0:01:40.800 --> 0:01:42.240 You know I'm not going to elbow my way in 0:01:42.280 --> 0:01:45.360 that line. Well, welcome to our podcast where you are 0:01:45.440 --> 0:01:48.200 first in line to hear this. It's called Daniel and 0:01:48.280 --> 0:01:51.040 Jorge Explain the Universe, a production of I Heart Radio 0:01:51.120 --> 0:01:54.080 where normally we take you on a mental trip around 0:01:54.160 --> 0:01:57.800 the cosmos, zooming out from the tiniest little particles that 0:01:57.840 --> 0:02:00.600 define the basic building blocks of the universe all the 0:02:00.600 --> 0:02:04.320 way out to the grandest structures that shape the nature 0:02:04.320 --> 0:02:06.080 of the cosmos itself. Yeah. I just think it was 0:02:06.160 --> 0:02:09.400 as your guide, as your personal GPS to all of 0:02:09.400 --> 0:02:12.560 the amazing and wonderful things that are in the universe 0:02:12.560 --> 0:02:15.000 and also all of the unknown things that are out 0:02:15.000 --> 0:02:16.760 there for us to discover. Do you think we're a 0:02:16.760 --> 0:02:19.320 good mental GPS. Sometimes we get lost, We get on 0:02:19.360 --> 0:02:21.919 a discussion about neutrinos and we end up talking about 0:02:21.919 --> 0:02:25.399 snack foods. Well, you know, I think detours are part 0:02:25.400 --> 0:02:28.079 of the fun of a trip. Right. I wish that 0:02:28.200 --> 0:02:30.679 my navigation like Siri would tell me, like, hey, pull 0:02:30.720 --> 0:02:33.680 over and get some chips. There's a good snack shop 0:02:33.800 --> 0:02:36.359 right here. Why not? Yeah, that should be a setting, right, 0:02:37.360 --> 0:02:41.239 suggests snacks. I like that suggests yeah, AI engineers, get 0:02:41.240 --> 0:02:43.400 on it. Not in a hurry. Should be maybe an 0:02:43.400 --> 0:02:46.280 option open to wonderful discovery. That's right. And on this 0:02:46.360 --> 0:02:48.960 podcast we try to open your mind to all the 0:02:49.000 --> 0:02:52.240 future wonderful discoveries that science will bring us. And we 0:02:52.280 --> 0:02:55.280 do that by talking about the cutting edge of science, 0:02:55.560 --> 0:02:58.720 all the questions that science has not answered, all the 0:02:58.720 --> 0:03:00.880 things scientists are trying to think ground, and all the 0:03:00.919 --> 0:03:04.000 technical problems they're trying to solve on their journey to 0:03:04.040 --> 0:03:06.440 give us the answers. Yeah, because I think sometimes to 0:03:06.800 --> 0:03:09.760 think about a journey of discovery is the journey itself, 0:03:10.080 --> 0:03:15.080 you know, and the friends you make along the way. Yeah, 0:03:15.160 --> 0:03:16.480 you know, not just where you go and what do 0:03:16.480 --> 0:03:18.560 you find when you get there? For also how do 0:03:18.639 --> 0:03:20.639 you get there and how do you how do you 0:03:20.639 --> 0:03:22.440 even know where to go when you're going? Yeah, I 0:03:22.440 --> 0:03:25.680 think people imagine that it's hard to get to Jupiter 0:03:26.040 --> 0:03:28.640 or Pluto because it's so far out there. It's just 0:03:28.720 --> 0:03:31.640 like you gotta throw a rock really far into space, 0:03:32.040 --> 0:03:35.360 but it's not just really far away. It's like very 0:03:35.400 --> 0:03:38.160 hard to find. You know. Pluto is a small rock 0:03:38.240 --> 0:03:41.720 in the vast, vast reaches of space. If you're gonna 0:03:41.960 --> 0:03:44.720 throw something in that direction, you have to be really precise. 0:03:44.800 --> 0:03:46.640 You have to really know how to aim it and 0:03:46.680 --> 0:03:48.560 have to be able to course correct along the way. 0:03:48.600 --> 0:03:51.040 And that turns out to be not so easy. It's 0:03:51.120 --> 0:03:53.760 much harder than stopping for snacks. Yeah, you know, they 0:03:53.760 --> 0:03:56.840 have good snacks and jubiter. You know, it makes a 0:03:56.880 --> 0:03:59.160 little gassy at the end, but you know it's all 0:03:59.280 --> 0:04:02.560 totally worth it, right right the Red Storm chips. I 0:04:02.640 --> 0:04:05.440 love this. Yeah. So today we're gonna be asking a 0:04:05.520 --> 0:04:08.160 question that I personally have had a lot of curiosity 0:04:08.200 --> 0:04:10.760 about over the years. I've always wondered about this question, 0:04:10.840 --> 0:04:13.440 and even more so now recently I've been rewatching all 0:04:13.480 --> 0:04:16.240 the Star Wars movies and so this is a question 0:04:16.240 --> 0:04:18.679 that's really present in my mind that I've been asking 0:04:18.720 --> 0:04:21.520 myself recently, And why is that? Are you imagining how 0:04:21.600 --> 0:04:24.000 you're going to navigate to your in law's house on 0:04:24.040 --> 0:04:27.839 the Jovian moons from your vacation place in Saturn or 0:04:27.920 --> 0:04:30.000 what inspires you to think about this? Well, my wife 0:04:30.040 --> 0:04:31.800 and I are immigrants, but we're not that that kind 0:04:31.800 --> 0:04:36.440 of alien. But no, I just kind of wondered, you know, Um, 0:04:37.040 --> 0:04:39.479 in Star Wars they always get lost or they pop 0:04:39.560 --> 0:04:41.479 up in all kinds of places, and so how do 0:04:41.520 --> 0:04:43.960 you know where you are? And how do you know 0:04:43.960 --> 0:04:45.560 where to go? Or you know, they talk about like 0:04:45.600 --> 0:04:48.120 a map of the galaxy, what does that even look like? 0:04:48.200 --> 0:04:50.240 Or how would that even be useful? Yeah, it's it's 0:04:50.320 --> 0:04:52.880 very rare that they're like, make a wrong turn. They're like, 0:04:53.040 --> 0:04:55.520 we're we supposed to turn left at that pulsar or right. 0:04:55.560 --> 0:04:57.960 I don't even really remember. It feels like that's all 0:04:58.000 --> 0:05:00.360 just sort of been integrated into the electron next they 0:05:00.360 --> 0:05:02.800 have in front of them. But those are hard problems, right, 0:05:02.839 --> 0:05:05.400 it's not necessarily trivial to figure out. Yeah, and if 0:05:05.440 --> 0:05:07.600 you think about it, in popular culture, there's only been 0:05:07.680 --> 0:05:11.520 like one TV show about getting lost in space. You mean, 0:05:11.839 --> 0:05:15.080 it was called space and you know at least you 0:05:15.120 --> 0:05:17.400 know what it's about. Yeah, So today on the program, 0:05:17.440 --> 0:05:24.840 we'll be asking the question, how do you navigate in 0:05:24.960 --> 0:05:28.760 space space, and this is a problem that's relevant to 0:05:29.120 --> 0:05:32.719 future navigation. Like imagine you are flying a spaceship with 0:05:32.800 --> 0:05:34.719 lots of people on board and trying to get everybody 0:05:34.720 --> 0:05:38.039 safely to Alpha Centauri. And it's also a question today 0:05:38.160 --> 0:05:41.120 as NASA and the E s A launched satellites to 0:05:41.200 --> 0:05:43.600 explore our Solar system. How do they make sure they 0:05:43.640 --> 0:05:45.839 get to the right spot? How do they course correct 0:05:46.120 --> 0:05:48.760 if they are off? Who does those calculations? Is that 0:05:48.880 --> 0:05:51.120 on board the satellite or back here on Earth? Are 0:05:51.200 --> 0:05:55.240 there people with protractors and pencils scribbling things furiously? How 0:05:55.279 --> 0:05:57.719 does that actually work? Yeah, because you know, space is 0:05:57.760 --> 0:06:00.840 pretty big, and it's three dementi all, you know, at 0:06:00.920 --> 0:06:04.120 least three dimensions at least, yeah that we know of 0:06:05.240 --> 0:06:07.680 that we think about right now. But it's a multi 0:06:07.680 --> 0:06:11.600 dimensional and you're out there and you know, there's no 0:06:11.720 --> 0:06:15.839 mountain to reference, no street signs. How do you get around? 0:06:15.839 --> 0:06:17.120 How do you know where to go? Do you think 0:06:17.160 --> 0:06:18.880 that third dimension is going to lead to like a 0:06:18.920 --> 0:06:21.719 lot more marital arguments in the future, Like I told 0:06:21.720 --> 0:06:24.720 you to turn up at that move man, why did 0:06:24.800 --> 0:06:26.920 you turn down? This is just like so many more 0:06:26.920 --> 0:06:32.120 ways to call new dimension to divorces. Probably no, but 0:06:32.160 --> 0:06:34.880 it is really hard and it's also vital because you're 0:06:34.920 --> 0:06:39.000 so much further away from your resources. Like these spaceships 0:06:39.120 --> 0:06:41.640 they leave Earth, they're never getting a refill, like they 0:06:41.760 --> 0:06:44.280 run out of gas because they got lost. They're just lost. 0:06:44.760 --> 0:06:47.279 So you have like a very limited window to make 0:06:47.320 --> 0:06:50.040 the moves you need to make to enter that orbit 0:06:50.160 --> 0:06:53.120 or to fly by the moon. There's no reduce, like 0:06:53.200 --> 0:06:55.599 you have a one tank and that's it. So it's 0:06:55.680 --> 0:06:58.720 absolutely critical that you don't get lost and that you 0:06:58.760 --> 0:07:01.440 figure out how to get where you need to go. Yeah, So, 0:07:01.480 --> 0:07:03.680 as usually, we were wondering how many people out there 0:07:04.040 --> 0:07:06.279 have thought about this question or even have an idea 0:07:06.279 --> 0:07:09.360 about how to navigate in space. So as usual, Daniel 0:07:09.400 --> 0:07:12.120 went out there and ask the internet to try to 0:07:12.160 --> 0:07:15.200 answer this question, how do you navigate in space? That's right, 0:07:15.200 --> 0:07:18.320 and if you'd like to participate in our virtual person 0:07:18.440 --> 0:07:21.040 on the street interviews, just shoot us an email two 0:07:21.120 --> 0:07:23.960 questions at Daniel and Jorge dot com. We would love 0:07:24.000 --> 0:07:26.640 to put your uninformed speculation on the podcast. And so 0:07:26.680 --> 0:07:28.560 think about it for a second. If you were out 0:07:28.640 --> 0:07:31.440 in space in the middle of the galaxy or in 0:07:31.480 --> 0:07:34.320 between galaxies? How would you know which way to make 0:07:34.320 --> 0:07:36.560 your way home? Here's what people had to say. Because 0:07:36.600 --> 0:07:39.640 gravity distill space and time and everything. Maybe you'd have 0:07:39.760 --> 0:07:42.240 to go. Maybe you'd have to shoot a little bit 0:07:42.240 --> 0:07:45.920 off it because as you as you go close to 0:07:46.040 --> 0:07:50.520 and an object, you'd kind of be taken into its 0:07:50.680 --> 0:07:53.720 gravitational swing. Other than that, I don't know how do 0:07:53.800 --> 0:07:56.760 you navigate through deep space to just keep a set 0:07:56.760 --> 0:07:59.480 of stars to your left and hopefully you're going the 0:07:59.520 --> 0:08:03.720 same direct action. I have no idea. Maybe like by 0:08:03.760 --> 0:08:08.000 distracting energy from the Sun, or if we're very patient, 0:08:08.040 --> 0:08:12.080 maybe with solar sales, we could navigate deep space, maybe 0:08:12.200 --> 0:08:15.960 through a pulse of a star, or like I don't know, 0:08:16.120 --> 0:08:18.760 pole stars or something. I think the only way you 0:08:18.760 --> 0:08:20.880 can navigating these spaces the way we do it now 0:08:20.920 --> 0:08:24.320 by using stars and galaxies, things that are consistent, not 0:08:24.360 --> 0:08:27.720 necessarily constellations, because that could you know, in three D 0:08:27.800 --> 0:08:30.440 space they have depth and they have angles that they 0:08:30.440 --> 0:08:34.120 are relative each other. You know, constellations do. But if 0:08:34.120 --> 0:08:36.760 you use stuff like pulsars and quasars and you know 0:08:36.800 --> 0:08:40.160 the Andromeda gag, see those things, we can coordinate ourselves 0:08:40.240 --> 0:08:42.520 using a couple of those angles, we can coordinate ourselves 0:08:42.520 --> 0:08:45.040 in deep space. I think navere taking in a deep 0:08:45.120 --> 0:08:49.400 space or americum woulds to need the bicycles of navigation. 0:08:51.280 --> 0:08:55.440 You're do either use inertial navigation, sitting time, speed, and 0:08:55.480 --> 0:08:57.760 directions from someone In a short stuff you will have 0:08:57.880 --> 0:09:03.120 to pick something like the sun and navigating reference to 0:09:03.160 --> 0:09:06.520 the sun. Let's see, if you're heading to a prime centuri, 0:09:06.760 --> 0:09:09.559 we should at least have an inbuilt special I had 0:09:09.559 --> 0:09:15.800 invisible telescopes, I mean lens and meadows and special lists 0:09:16.360 --> 0:09:22.520 and optimal path correction systems and some kind of special clocks. 0:09:23.480 --> 0:09:26.199 Navigating in deep space, I would have to assume is 0:09:26.280 --> 0:09:29.280 much like seiling the ocean. You look at the stars 0:09:29.360 --> 0:09:32.880 and see whe're at relative to the stars. After your 0:09:34.000 --> 0:09:39.880 statement that space is expanding faster than um the speed 0:09:39.880 --> 0:09:42.640 of light, or faster than light can travel through it, 0:09:43.840 --> 0:09:49.040 I really have no idea. Now I think you could 0:09:49.040 --> 0:09:53.880 go anywhere you you go. Yeah, well, hopefully you can 0:09:53.880 --> 0:09:56.640 do that, but how you do it? My idea would 0:09:56.679 --> 0:09:59.720 be to mount a big giant telescope on the top 0:09:59.760 --> 0:10:03.080 of your spacecraft, on the front and the back, so 0:10:03.160 --> 0:10:05.559 you can see where you're going and where you're where 0:10:05.559 --> 0:10:07.800 you came from. Maybe a telescope as big as hubble, 0:10:07.840 --> 0:10:09.920 because your spacecraft is going to have to be that big. 0:10:10.000 --> 0:10:14.160 After we leave the planet and learn about the like 0:10:14.320 --> 0:10:17.880 further stars that we don't see on Earth, we can 0:10:17.960 --> 0:10:21.160 pick three stars, and by keeping track of the distance 0:10:21.280 --> 0:10:24.920 between us and the stars, we can know our position. 0:10:25.640 --> 0:10:29.360 And when the stars are too far away, we can 0:10:29.440 --> 0:10:34.320 always peak three new stars that we found out about 0:10:35.080 --> 0:10:37.600 along the way in our journey. So there are a 0:10:37.600 --> 0:10:39.079 lot of ideas there. What do you think of that? 0:10:39.320 --> 0:10:41.560 Pretty good? Pretty good? I feel like people were sort 0:10:41.559 --> 0:10:45.240 of thinking about triangulation and using the stars somehow to 0:10:45.480 --> 0:10:47.240 tell where you are. I feel like that's a pretty 0:10:47.240 --> 0:10:50.920 common idea in science fiction movies and boots. It's like, oh, 0:10:50.960 --> 0:10:53.360 you just look at the stars around you, and do 0:10:53.400 --> 0:10:54.960 you know where you are and you know where to go? 0:10:55.160 --> 0:10:56.640 Or like if you look at the stars and you 0:10:56.679 --> 0:10:59.520 don't recognize things, then you're kind of in trouble. I 0:10:59.600 --> 0:11:01.800 like the I said, let's put a huge telescope on 0:11:01.840 --> 0:11:03.880 the front and on the back of your spaceship, because 0:11:04.480 --> 0:11:06.720 I want that anyway, Like, if I'm flying through space, 0:11:06.760 --> 0:11:08.520 I want a big telescope because I want to see 0:11:08.520 --> 0:11:10.120 with what stuffed around me. You know, I want to 0:11:10.160 --> 0:11:12.240 do some sight seeing when I'm out there. But what 0:11:12.360 --> 0:11:13.960 do you need one in the bag though, just to 0:11:14.040 --> 0:11:18.120 see the fit is of people that you leave behind. Well, 0:11:18.160 --> 0:11:20.840 because I mean, I guess you could turn your telescope. 0:11:20.840 --> 0:11:23.600 Maybe you're saying you'll need one telescope plus like a 0:11:23.640 --> 0:11:27.160 mount or something, but hey, more telescopes are better. Well, 0:11:27.200 --> 0:11:29.120 I feel like that is a sort of a common thing, 0:11:29.200 --> 0:11:31.120 is to look at the stars around you, and somehow 0:11:31.120 --> 0:11:32.839 you use that to orient yourself, you know, kind of 0:11:32.880 --> 0:11:35.400 like we use the North Star for a long time 0:11:35.440 --> 0:11:37.439 to kind of tell which way was north when you're 0:11:37.440 --> 0:11:39.559 out in the middle of the ocean. Is that kind 0:11:39.600 --> 0:11:41.600 of an idea that we can use at all? It 0:11:41.720 --> 0:11:43.280 is an idea that we can use. And the rest 0:11:43.320 --> 0:11:45.480 on this notion that if you have an accurate map 0:11:45.600 --> 0:11:48.040 of the stars, you can compare that to what you're 0:11:48.080 --> 0:11:51.880 seeing and look for landmarks and try to measure angles 0:11:51.920 --> 0:11:54.040 between the stars to give you a sense for where 0:11:54.080 --> 0:11:57.600 you are. For example, if two stars are almost lined 0:11:57.679 --> 0:11:59.920 up in your vision, then that tells you that you're 0:12:00.040 --> 0:12:03.200 along a line drawn between those two stars. And if 0:12:03.240 --> 0:12:07.240 you can find other examples measuring angles between stars, you 0:12:07.240 --> 0:12:09.240 can give you sort of a point in three D 0:12:09.400 --> 0:12:11.880 space for where you are at that moment. Well, I 0:12:12.080 --> 0:12:14.080 guess the problem that I have always should have thought 0:12:14.120 --> 0:12:15.920 about is like, what if you find yourself on the 0:12:15.960 --> 0:12:18.439 other side of the galaxy, how would you even recognize 0:12:18.520 --> 0:12:20.640 any of the stars because the stars are gonna look 0:12:20.679 --> 0:12:23.480 totally different from the other side of the galaxy. Yeah, 0:12:23.480 --> 0:12:25.880 if you just look at like teleported to a random 0:12:25.920 --> 0:12:28.760 place in the universe where you have no reference points, 0:12:28.960 --> 0:12:31.840 there's literally no way to know where you are because 0:12:31.960 --> 0:12:35.200 there's no absolute reference there's no like point in space 0:12:35.240 --> 0:12:38.560 that's defined in zero and you can measure your location 0:12:38.640 --> 0:12:41.560 relative to that. If you get teleported to an arbitrary 0:12:41.600 --> 0:12:44.880 point in space, special relativity says it's impossible to know 0:12:44.920 --> 0:12:48.080 where you are. You can only measure your distance relative 0:12:48.120 --> 0:12:50.280 to other stuff. So if you have no familiar references, 0:12:50.520 --> 0:12:53.760 you're totally screwed. Wow, and things are like changing in time. Also, 0:12:53.920 --> 0:12:56.720 everything's moving, so you're sort of totally lost in You're 0:12:56.760 --> 0:12:59.280 totally lost. You have. The only way to orient yourself 0:12:59.320 --> 0:13:02.440 in space is relative to known things. So if you 0:13:02.480 --> 0:13:05.640 get teleported to some part of space that's totally unfamiliar. 0:13:06.040 --> 0:13:08.800 Then you literally have no way to find your way 0:13:08.800 --> 0:13:12.400 back except for randomly exploring until you do find a landmark. 0:13:12.760 --> 0:13:14.079 And when I try that the next time I get 0:13:14.120 --> 0:13:17.960 lost and my spouse is complaining, I'm like, it's special relativity. 0:13:18.160 --> 0:13:20.680 It's it's law of the universe. It's not my fault. 0:13:20.840 --> 0:13:24.079 Daniel said, this should work. Don't you feel like smartphones 0:13:24.160 --> 0:13:27.720 must have solved this marital complaint? Right, houses don't have 0:13:27.720 --> 0:13:29.720 to argue about how to navigating anymore, and they just 0:13:29.840 --> 0:13:32.600 listened to the phone. That's right. The phone has saved 0:13:32.600 --> 0:13:35.680 a lot of marriages. Probably maybe, or maybe people are like, no, 0:13:35.800 --> 0:13:38.439 listen to my phone. Well, my phone says it's faster 0:13:38.520 --> 0:13:43.400 take the expressway using Google Maps. No way, we aren't 0:13:43.480 --> 0:13:46.760 using ways. People who argue are going to argue anyway. 0:13:46.880 --> 0:13:50.080 I guess, So I guess the phones can't fix that. Yeah, 0:13:50.120 --> 0:13:53.920 And you know, navigators in throughout history have used the stars. 0:13:53.960 --> 0:13:56.360 Like if you have sailed the oceans, then to figure 0:13:56.360 --> 0:13:59.120 out where you are in this vast sea where you 0:13:59.160 --> 0:14:01.480 can see no land marks is just to look up 0:14:01.600 --> 0:14:04.440 and look for star marks. Right, to look for the 0:14:04.440 --> 0:14:06.520 positions of stars in the sky that gives you a 0:14:06.520 --> 0:14:08.640 sense for where you might be. All right, well, let's 0:14:08.640 --> 0:14:11.120 get into the sort of the nitty gritty of this problem. 0:14:11.280 --> 0:14:13.000 And because I know you, you've told me that there 0:14:13.040 --> 0:14:16.200 are sort of several ways in which we can right 0:14:16.200 --> 0:14:18.480 now sort of calculate where we are in space, you know, 0:14:18.559 --> 0:14:22.440 barring kind of like a complete map of the entire galaxy. Um, 0:14:22.440 --> 0:14:24.320 so step us through. What's the what's the sort of 0:14:24.360 --> 0:14:26.760 the basic way that we get around in space. So 0:14:26.800 --> 0:14:29.200 the simplest way, in the dumbest way, and the worst 0:14:29.280 --> 0:14:33.080 way is basically dead reckoning. And that says you know 0:14:33.160 --> 0:14:36.000 where you started, and you started on Earth, and if 0:14:36.000 --> 0:14:38.320 you have a record of all the moves you took, 0:14:38.520 --> 0:14:41.080 you went in this direction at this velocity, you should 0:14:41.080 --> 0:14:43.680 be able to calculate where you went. Because you know, 0:14:43.800 --> 0:14:46.840 spacecraft follow the laws of physics, and we know what 0:14:46.920 --> 0:14:49.400 those laws are. We have a whole model of the 0:14:49.440 --> 0:14:52.360 Solar System, so we should be able to predict if 0:14:52.400 --> 0:14:55.120 you leave in this direction at this time, and you 0:14:55.200 --> 0:14:57.640 fire your rockets here and there, we should be able 0:14:57.640 --> 0:14:59.880 to predict where you end up. That's kind of like 0:15:00.040 --> 0:15:03.320 closing your eyes and like knowing where you are right now, 0:15:03.360 --> 0:15:05.880 closing your eyes and just by like counting your steps 0:15:06.280 --> 0:15:08.680 and how you think you turn, sort of like making 0:15:08.720 --> 0:15:10.360 it to your fridge or something like that. It's like 0:15:10.360 --> 0:15:13.200 following one of those treasure maps, like fifteen paces forward 0:15:13.440 --> 0:15:17.080 then turn left step four paces, then dig right right. 0:15:17.360 --> 0:15:19.640 And that's a little terrifying. Like if you remember the 0:15:19.720 --> 0:15:22.960 days before smartphones where people had to like actually write 0:15:22.960 --> 0:15:26.080 down directions and there were things like drive for fifteen 0:15:26.080 --> 0:15:28.600 miles then take a left right, and you had no 0:15:28.680 --> 0:15:32.360 idea is this the correct left or not? You know, yeah, yeah, 0:15:32.400 --> 0:15:33.640 and we all know how well that works. In the 0:15:33.680 --> 0:15:34.760 middle of the night when you have to go to 0:15:34.800 --> 0:15:39.320 the bathroom in total darkness, you know, you better put 0:15:39.320 --> 0:15:41.080 your hands in front of you, just in cakes. Yeah, 0:15:41.120 --> 0:15:44.120 and so sailors used to call this dead reckoning, and 0:15:44.200 --> 0:15:47.040 you know it's not terrible, like it works. Okay, we 0:15:47.120 --> 0:15:49.640 have a pretty good model of the solar system, and 0:15:49.920 --> 0:15:52.000 we have rockets, and we can even measure we don't 0:15:52.040 --> 0:15:54.440 even have to just guess. And like the effect of thrust, 0:15:54.480 --> 0:15:59.080 you can measure how much you've accelerated using accelerometers, you 0:15:59.120 --> 0:16:01.440 can measure your the direction that you ended up in 0:16:01.560 --> 0:16:05.280 using gyroscopes, So we've tried to be really careful about this, 0:16:05.320 --> 0:16:08.280 and some spacecraft in the history of you know, American 0:16:08.360 --> 0:16:11.920 exploration have used dead reckoning. But I guess it's tricky too, 0:16:11.960 --> 0:16:15.240 because you know, in space you can't count your steps, 0:16:15.280 --> 0:16:17.280 like there's nothing to hold onto to tell you how 0:16:17.320 --> 0:16:20.000 far you move. You have to you have to measure 0:16:20.040 --> 0:16:24.240 your exploration and then integrate DAD to convert to velocity, 0:16:24.280 --> 0:16:26.880 and then integrate DAT to convert it to distance. So 0:16:26.960 --> 0:16:29.680 it's like a lot of room there to get error. Yes, 0:16:29.680 --> 0:16:33.000 and you mentioned a very critical step there, which is integration, 0:16:33.080 --> 0:16:36.280 and that requires knowing the time. You can't count your steps. 0:16:36.440 --> 0:16:39.360 What you need is a very accurate clock. And the 0:16:39.400 --> 0:16:42.080 more accurate your clock, the more you accurately you can 0:16:42.080 --> 0:16:45.240 calculate how far you've gone. Right, you said I shot 0:16:45.240 --> 0:16:47.280 off in this direction of the speed, Well did you 0:16:47.280 --> 0:16:50.240 go for two point seven seconds or two point eight seconds? 0:16:50.400 --> 0:16:53.600 When you're traveling at ten thousand kilometers per second, that 0:16:53.680 --> 0:16:57.640 makes a big difference. Yeah, And when distances are so huge, right, 0:16:57.920 --> 0:17:00.480 and the stakes are so high, like you can't if 0:17:00.480 --> 0:17:02.600 you miss Jupiter by a few miles, it could be 0:17:02.640 --> 0:17:05.520 bad us. Yeah, as you're gonna do a Jupiter drive by, right, 0:17:05.840 --> 0:17:08.480 then you only get one shot at it, literally, and 0:17:08.560 --> 0:17:11.000 so it's pretty tricky. And the problem here is that 0:17:11.200 --> 0:17:13.840 errors build up, Like you make a little mistake because 0:17:13.880 --> 0:17:16.520 you turned a little too far, then you're off, and 0:17:16.520 --> 0:17:18.560 the next time you can't correct it, and so the 0:17:18.680 --> 0:17:21.199 errors just build up in the integrate and eventually you 0:17:21.200 --> 0:17:23.520 can be pretty far from where you thought you right. 0:17:23.600 --> 0:17:27.119 It literally is like walking around with your eyes closed. Yeah, exactly. 0:17:27.280 --> 0:17:30.640 So that's the most basic strategy, and you can make 0:17:30.680 --> 0:17:33.640 that more sophisticated by doing corrections. You can say, well, 0:17:33.840 --> 0:17:37.040 I'm gonna use dead reckoning. Plus I'm going to look 0:17:37.040 --> 0:17:39.000 at the stars and I'm gonna try to figure out 0:17:39.160 --> 0:17:41.359 if I'm off. And this is what like a lot 0:17:41.400 --> 0:17:44.400 of astronauts did, like Apollo eleven and follow their team. 0:17:44.560 --> 0:17:48.080 They flew to the Moon by dead reckoning, but occasionally 0:17:48.119 --> 0:17:50.000 they would check in and they would look at the 0:17:50.040 --> 0:17:52.560 stars and try to get a more precise measurement for 0:17:52.600 --> 0:17:54.400 where they were, and they would use that to correct 0:17:54.600 --> 0:17:57.720 their flight path. Really, so I guess two questions. One 0:17:57.840 --> 0:18:00.480 is why didn't they just use the moon as reference 0:18:00.800 --> 0:18:03.480 because they were flying towards it, and they could tell 0:18:03.480 --> 0:18:06.399 her they were going away from it or towards it. 0:18:06.560 --> 0:18:08.159 And the size of it too, wouldn't it tell you 0:18:08.160 --> 0:18:10.399 said of the distance? But and then my second question was, 0:18:11.000 --> 0:18:13.280 you know, can you actually use the stars to tell 0:18:13.280 --> 0:18:16.280 where you are? You can? So, yes, they were pointed 0:18:16.280 --> 0:18:18.320 at the moon. But that's pretty rough, right, And what 0:18:18.359 --> 0:18:20.240 you want to do was get to the Moon and 0:18:20.240 --> 0:18:22.879 then enter into orbit around the Moon. And that was 0:18:22.880 --> 0:18:26.400 a very precise maneuver. And just like with the spacecraft, 0:18:26.440 --> 0:18:28.400 they had a limited amount of fuel, so if they 0:18:28.440 --> 0:18:30.480 burnt their fuel the wrong time, they might not be 0:18:30.520 --> 0:18:32.680 able to make it home. I said. The fuel is 0:18:32.760 --> 0:18:34.880 very expensive to lift off the surface of the Earth, 0:18:34.960 --> 0:18:37.600 and so everything was a very tight budget, so they 0:18:37.600 --> 0:18:41.240 had to be really precise. There are no exactly you 0:18:41.280 --> 0:18:43.639 can't just pull a eui in space. That costs a 0:18:43.680 --> 0:18:45.879 lot of energy to pull ui. Like you missed the 0:18:45.920 --> 0:18:48.320 snack shop. You missed the snack shop, man, you are 0:18:48.359 --> 0:18:51.280 not going back. And yes, they did stellar navigation. They 0:18:51.359 --> 0:18:54.520 looked by I to find stars, and they measured the 0:18:54.560 --> 0:18:58.920 declination using gyroscopes and they use that to correct their calculations. 0:18:58.960 --> 0:19:01.240 A huge fraction of the time they actually spent in 0:19:01.280 --> 0:19:05.359 that module was typing data into that computer. You know, 0:19:05.480 --> 0:19:08.320 it's a complicated system. And remember the whole program was 0:19:08.400 --> 0:19:11.320 loaded into the computer before it launched, Like you didn't 0:19:11.359 --> 0:19:13.800 have guys up there, like you know, tip tapping editing 0:19:13.800 --> 0:19:16.119 the program being like I think we must change the 0:19:16.160 --> 0:19:18.639 flight path or something. They had it all built in 0:19:18.840 --> 0:19:22.000 with the opportunity for small corrections based on looking at 0:19:22.000 --> 0:19:24.640 those stars. So what do you mean declination like where 0:19:24.680 --> 0:19:27.520 the constellation was relative to the Earth or something like that. No, 0:19:27.680 --> 0:19:30.240 relative to them, Right, they had an idea for where 0:19:30.240 --> 0:19:32.159 they were, and they had an idea for if we 0:19:32.240 --> 0:19:35.440 are here, the stars should appear at this angle relative 0:19:35.480 --> 0:19:38.200 to the spaceship, and then they would measure where is 0:19:38.240 --> 0:19:41.240 the star relative to where the spaceship is pointing because 0:19:41.240 --> 0:19:45.120 I had careful gyroscopes and and those angles helped them 0:19:45.119 --> 0:19:48.320 figure out exactly where they are. All right, Well that 0:19:48.359 --> 0:19:50.720 sounds like, um it worked because they got to the 0:19:51.840 --> 0:19:55.359 a few times, So I can't argue with that. All right, Well, 0:19:55.440 --> 0:19:57.320