1 00:00:01,160 --> 00:00:04,720 Speaker 1: Hey, welcome to Science Stuff, the production of iHeartRadio. I'm 2 00:00:04,720 --> 00:00:08,920 Speaker 1: Moreham and today we are going to space. No, we're 3 00:00:08,920 --> 00:00:11,639 Speaker 1: not going to strap ourselves to a giant rocket full 4 00:00:11,680 --> 00:00:21,200 Speaker 1: of flammable fuel. Instead, we are going to take the elevator. 5 00:00:25,880 --> 00:00:29,120 Speaker 1: It may seem like science fiction, but a space elevator 6 00:00:29,240 --> 00:00:33,160 Speaker 1: is something serious scientists actually think is possible to build. 7 00:00:33,600 --> 00:00:35,680 Speaker 1: And it's not just something that can take you to space. 8 00:00:36,280 --> 00:00:39,720 Speaker 1: It might actually help you get to other planets. To 9 00:00:39,720 --> 00:00:43,720 Speaker 1: put on some relaxing music, step inside and ride with 10 00:00:43,880 --> 00:00:47,120 Speaker 1: us as we go up to answer the question, can 11 00:00:47,159 --> 00:00:49,919 Speaker 1: we build an elevator to space? 12 00:00:56,240 --> 00:00:56,440 Speaker 2: Hey? 13 00:00:56,440 --> 00:01:00,400 Speaker 1: Everyone, Okay, today we are tackling a pretty wild idea, 14 00:01:00,440 --> 00:01:03,000 Speaker 1: which is to build an elevator that can take you 15 00:01:03,240 --> 00:01:06,160 Speaker 1: to space. But I promise you that by the end 16 00:01:06,360 --> 00:01:09,720 Speaker 1: you're going to be thinking, my gosh, that totally makes sense. 17 00:01:10,160 --> 00:01:13,399 Speaker 1: Let's build one right now. Now. To get there, I 18 00:01:13,480 --> 00:01:16,559 Speaker 1: need you to imagine that you're getting into an elevator, 19 00:01:17,000 --> 00:01:19,480 Speaker 1: and at each floor we're going to be answering a 20 00:01:19,520 --> 00:01:25,680 Speaker 1: different question about space elevators. So step inside, perfect now, 21 00:01:25,760 --> 00:01:35,199 Speaker 1: hit the button for the first floor, and we're going up. Okay, 22 00:01:35,319 --> 00:01:37,679 Speaker 1: while we go up, I'll just tell you that the 23 00:01:37,760 --> 00:01:40,720 Speaker 1: idea of a space elevator is that instead of taking 24 00:01:40,720 --> 00:01:44,720 Speaker 1: a rocket to go to space, you just take an elevator. 25 00:01:45,120 --> 00:01:47,640 Speaker 1: There would be a structure that is based here on Earth, 26 00:01:48,120 --> 00:01:51,280 Speaker 1: and it would extend up past the tallest building we've 27 00:01:51,280 --> 00:01:56,680 Speaker 1: ever built, past the clouds, past the atmosphere, and into space. 28 00:01:57,560 --> 00:01:59,520 Speaker 1: And so if you want to go to space or 29 00:01:59,680 --> 00:02:02,840 Speaker 1: take something into space, all you have to do is 30 00:02:02,920 --> 00:02:06,480 Speaker 1: get on, and then you'd be in space. And if 31 00:02:06,520 --> 00:02:09,240 Speaker 1: you go up high enough, when you get off, you'll 32 00:02:09,240 --> 00:02:13,040 Speaker 1: actually be in orbit around Earth, meaning you wouldn't fall 33 00:02:13,120 --> 00:02:17,880 Speaker 1: back down to Earth. Oh, which has got to our 34 00:02:17,919 --> 00:02:22,720 Speaker 1: first stop. Okay, Here, I imagine we are ten kilometers 35 00:02:22,800 --> 00:02:25,800 Speaker 1: above the surface of the Earth. This is about twelve 36 00:02:25,800 --> 00:02:29,000 Speaker 1: times higher than the Birch Khalifa, which is the highest 37 00:02:29,000 --> 00:02:32,600 Speaker 1: building we've ever built. Here, at ten kilometers, we're at 38 00:02:32,600 --> 00:02:35,560 Speaker 1: the top of the troposphere, which is the main layer 39 00:02:35,760 --> 00:02:38,600 Speaker 1: of our atmosphere. It's the lear where all the weather 40 00:02:38,680 --> 00:02:41,360 Speaker 1: happens because it has most of the water that's in 41 00:02:41,360 --> 00:02:44,640 Speaker 1: the atmosphere. And this is about as high as even 42 00:02:44,639 --> 00:02:50,720 Speaker 1: the highest clouds go. Oh, and here joining us is 43 00:02:50,760 --> 00:02:55,080 Speaker 1: our first expert, Professor Matthew Pete, come in, doctor Pete, 44 00:02:55,360 --> 00:02:56,440 Speaker 1: thanks for joining us. 45 00:02:56,639 --> 00:02:57,840 Speaker 2: Well, thank you for having me. 46 00:02:58,360 --> 00:03:00,720 Speaker 1: Keith, Please tell us who you are and you do so. 47 00:03:00,760 --> 00:03:04,480 Speaker 2: I'm a professor at Arizona State University and teach and 48 00:03:04,560 --> 00:03:09,360 Speaker 2: do research in orbital mechanics and controls and dynamical systems theory. 49 00:03:09,760 --> 00:03:11,640 Speaker 1: Okay, so to thee on the program, we're answering the 50 00:03:11,720 --> 00:03:14,880 Speaker 1: question what is a space elevator? So where did this 51 00:03:15,040 --> 00:03:15,880 Speaker 1: idea come from? 52 00:03:16,120 --> 00:03:18,040 Speaker 2: Well, you know, that's an interesting story. 53 00:03:18,400 --> 00:03:18,880 Speaker 1: Arthur C. 54 00:03:19,000 --> 00:03:21,600 Speaker 2: Clark had a great paper on this and he counted 55 00:03:21,600 --> 00:03:23,400 Speaker 2: the number of times it had been reinvented, and I 56 00:03:23,440 --> 00:03:25,800 Speaker 2: think he was at eleven. The first invention of the 57 00:03:25,840 --> 00:03:29,880 Speaker 2: space elevator was by Konstancy Sokowsky. If you don't know 58 00:03:29,919 --> 00:03:32,320 Speaker 2: who is you might be forgiven. But he was one 59 00:03:32,360 --> 00:03:36,200 Speaker 2: of these very early rockets guys, and living in a 60 00:03:36,240 --> 00:03:40,280 Speaker 2: cabin outside of Moscow back in eighteen ninety five. What 61 00:03:40,400 --> 00:03:43,480 Speaker 2: he was doing inventing rockets and space elevators we could 62 00:03:43,520 --> 00:03:47,560 Speaker 2: leave to our imagination. So who knows what he was 63 00:03:47,560 --> 00:03:50,760 Speaker 2: doing out in his cabin. But although famous for space elevators, 64 00:03:50,800 --> 00:03:54,680 Speaker 2: he's of course far more famous for inventing the rocket equation. 65 00:03:55,040 --> 00:03:58,360 Speaker 2: So he laid out the basic mathematical foundations for the 66 00:03:58,440 --> 00:03:59,960 Speaker 2: use of rockets back in eighteen ninety. 67 00:04:00,560 --> 00:04:03,160 Speaker 1: So he sort of invented rocket signs in a way. 68 00:04:03,600 --> 00:04:06,360 Speaker 2: Yeah, I would give him credit for inventing rocket scignen. 69 00:04:06,440 --> 00:04:07,960 Speaker 1: So the same person who came up with the rocket 70 00:04:08,000 --> 00:04:10,360 Speaker 1: equation came up with this idea of the space elevator 71 00:04:10,400 --> 00:04:11,040 Speaker 1: for the first time. 72 00:04:11,120 --> 00:04:11,360 Speaker 3: Yeah. 73 00:04:11,400 --> 00:04:14,320 Speaker 2: He was inspired by the Eiffel Tower and how far 74 00:04:14,360 --> 00:04:16,560 Speaker 2: it reached up, and he said, well, if you reach 75 00:04:16,680 --> 00:04:19,240 Speaker 2: far enough, you could just drop things off the ever 76 00:04:19,440 --> 00:04:21,880 Speaker 2: tower and it we'd be in orbit. So he laid 77 00:04:21,880 --> 00:04:24,479 Speaker 2: out the basics and then it was invented a couple 78 00:04:24,520 --> 00:04:25,880 Speaker 2: more times. 79 00:04:25,360 --> 00:04:27,520 Speaker 1: Like people would just come up with it and work 80 00:04:27,560 --> 00:04:30,520 Speaker 1: it out without knowing what somebody else had already done. 81 00:04:30,760 --> 00:04:33,520 Speaker 2: Yeah, because it's an eminently logical and interesting idea. 82 00:04:34,560 --> 00:04:37,280 Speaker 1: So this idea of a space elevator that we're writing 83 00:04:37,360 --> 00:04:41,920 Speaker 1: right now came up a long time ago, back before 84 00:04:41,960 --> 00:04:45,240 Speaker 1: we even had rockets, And he keeps popping up over 85 00:04:45,400 --> 00:04:48,279 Speaker 1: and over again over the last one hundred and thirty 86 00:04:48,360 --> 00:04:51,800 Speaker 1: years because it kind of makes sense. If you want 87 00:04:51,800 --> 00:04:54,320 Speaker 1: to get to space, why not just build something that 88 00:04:54,400 --> 00:05:02,839 Speaker 1: can get you there directly. Oh, we're in our next up. Okay, 89 00:05:03,200 --> 00:05:06,640 Speaker 1: Here we are one hundred kilometers above the surface of 90 00:05:06,640 --> 00:05:09,919 Speaker 1: the Earth, meaning about one hundred and twenty times the 91 00:05:10,000 --> 00:05:14,240 Speaker 1: height of the bird khalifa. Oh, what's your step? You 92 00:05:14,360 --> 00:05:17,920 Speaker 1: definitely don't want to fall from here. At one hundred kilometers, 93 00:05:18,160 --> 00:05:22,200 Speaker 1: this is what's called the Carmen line. We're technically still 94 00:05:22,200 --> 00:05:24,680 Speaker 1: in the atmosphere, but this is the point that people 95 00:05:24,720 --> 00:05:29,200 Speaker 1: say separates being on Earth and being in space. It's 96 00:05:29,200 --> 00:05:32,479 Speaker 1: a little bit of an arbitrary number, mostly chosen because 97 00:05:32,560 --> 00:05:35,480 Speaker 1: one hundred kilometers is a nice round number. But at 98 00:05:35,480 --> 00:05:38,880 Speaker 1: around this level is where airplanes can no longer fly 99 00:05:39,400 --> 00:05:42,880 Speaker 1: or stay flying, because there isn't enough air to keep 100 00:05:42,920 --> 00:05:49,000 Speaker 1: them afloat. It's also around here that there isn't enough 101 00:05:49,040 --> 00:05:52,560 Speaker 1: air to burn up meteorites, so if you see shooting stars, 102 00:05:52,920 --> 00:05:56,160 Speaker 1: they would be below you. It's also where the International 103 00:05:56,360 --> 00:06:01,680 Speaker 1: Aeronautic Federation defines the beginning of space, which technically means 104 00:06:01,839 --> 00:06:06,160 Speaker 1: you and I in this space elevator are now officially astronauts, 105 00:06:06,680 --> 00:06:09,719 Speaker 1: although if you step outside right now, you would basically 106 00:06:09,800 --> 00:06:13,440 Speaker 1: just fall straight down because the force of gravity is 107 00:06:13,480 --> 00:06:16,200 Speaker 1: pretty much the same as on the surface of Earth. 108 00:06:16,640 --> 00:06:20,720 Speaker 1: It's only three percent lower. Okay, let's keep going like 109 00:06:20,800 --> 00:06:22,640 Speaker 1: the pet. Can you please press a button for the 110 00:06:22,680 --> 00:06:27,320 Speaker 1: next floor, of course. Okay, our next stop is going 111 00:06:27,400 --> 00:06:31,040 Speaker 1: to be one thousand kilometers above the surface of Earth. 112 00:06:31,360 --> 00:06:32,800 Speaker 1: It's going to take a little bit to get there. 113 00:06:32,960 --> 00:06:35,599 Speaker 1: So in the meantime, dark the peed. Can you tell 114 00:06:35,680 --> 00:06:38,039 Speaker 1: us why build this space elevator? 115 00:06:40,080 --> 00:06:44,800 Speaker 2: So the obvious reason is that if you're not using 116 00:06:44,800 --> 00:06:48,480 Speaker 2: a space elevator, the alternative is a rocket, and rockets 117 00:06:48,560 --> 00:06:52,560 Speaker 2: are dangerous and rather explosive. And there's this thing called 118 00:06:52,560 --> 00:06:55,680 Speaker 2: the rocket equation, which tells you that the amount of 119 00:06:55,720 --> 00:06:58,479 Speaker 2: propellant you need to get a certain amount of mass 120 00:06:58,560 --> 00:07:01,920 Speaker 2: up into space grows very large the farther you go up, 121 00:07:02,160 --> 00:07:05,480 Speaker 2: so that the fraction of mass to propellant would be 122 00:07:05,920 --> 00:07:08,680 Speaker 2: maybe one thousand to one, right, a lot of propellant 123 00:07:08,720 --> 00:07:10,160 Speaker 2: for very little mass to get up there. If you 124 00:07:10,200 --> 00:07:12,400 Speaker 2: want to put a city on space, for example, it 125 00:07:12,400 --> 00:07:14,120 Speaker 2: would be very difficult with rockets. 126 00:07:16,000 --> 00:07:19,000 Speaker 1: Okay, what doctor P is saying is that rockets are 127 00:07:19,040 --> 00:07:23,440 Speaker 1: just fundamentally inefficient, and that's because of something called the 128 00:07:23,600 --> 00:07:27,160 Speaker 1: rocket equation. It tells you that the amount of fuel 129 00:07:27,360 --> 00:07:30,800 Speaker 1: you need to put something in space using rockets grows 130 00:07:30,880 --> 00:07:34,600 Speaker 1: exponentially the more mass you want to take to space. 131 00:07:35,160 --> 00:07:37,680 Speaker 1: That's because in a rocket, you not only have to 132 00:07:37,800 --> 00:07:40,240 Speaker 1: lift the thing you want to take to space, you 133 00:07:40,280 --> 00:07:42,480 Speaker 1: also have to lift all the fuel you're going to 134 00:07:42,560 --> 00:07:45,000 Speaker 1: need along the way, and that's going to make your 135 00:07:45,120 --> 00:07:48,960 Speaker 1: rocket heavier. So you need to bring more fuel, which 136 00:07:49,120 --> 00:07:52,320 Speaker 1: makes your rocket even heavier, which means you need to 137 00:07:52,320 --> 00:07:56,520 Speaker 1: bring more fuel, et cetera, et cetera. This is why 138 00:07:56,640 --> 00:07:59,040 Speaker 1: when you look at a rocket, most of the long 139 00:07:59,120 --> 00:08:02,040 Speaker 1: cylinder that you see are the tanks for the fuel. 140 00:08:02,600 --> 00:08:05,040 Speaker 1: Only the small part of the bottom is the engine, 141 00:08:05,200 --> 00:08:08,280 Speaker 1: and only the very tippy top is where the astronauts sit. 142 00:08:08,960 --> 00:08:11,640 Speaker 1: So if we're ever going to launch a large spaceship 143 00:08:11,680 --> 00:08:14,520 Speaker 1: with food and people to other planets, it's going to 144 00:08:14,560 --> 00:08:17,920 Speaker 1: take a lot of fuel, and that brings other problems, 145 00:08:18,360 --> 00:08:19,120 Speaker 1: right like your beat. 146 00:08:19,600 --> 00:08:23,160 Speaker 2: Yes, so recent rockets tend to use slightly different fuels, 147 00:08:23,480 --> 00:08:27,440 Speaker 2: using etholocks and cara locks, which are petroleum based. So 148 00:08:27,440 --> 00:08:30,720 Speaker 2: there's an environmental question which says that if you're going 149 00:08:30,760 --> 00:08:32,760 Speaker 2: to put lots of things in space, well maybe it's 150 00:08:32,840 --> 00:08:35,480 Speaker 2: not a great idea to burn quite that much petroleum. 151 00:08:35,520 --> 00:08:38,120 Speaker 1: Product, it's not good for the environment. 152 00:08:38,320 --> 00:08:40,680 Speaker 2: Yeah, Okay. 153 00:08:40,960 --> 00:08:43,559 Speaker 1: When we come back, we're going to continue our elevator 154 00:08:43,640 --> 00:08:46,640 Speaker 1: ride into space, and we're going to talk about the 155 00:08:46,720 --> 00:08:51,079 Speaker 1: big question, which is how do you build a space elevator? 156 00:08:51,400 --> 00:08:54,640 Speaker 1: So don't hop off, keep writing with us. We'll be 157 00:08:54,840 --> 00:08:55,360 Speaker 1: right back. 158 00:09:02,679 --> 00:09:03,319 Speaker 3: Welcome back. 159 00:09:03,960 --> 00:09:07,800 Speaker 1: All right, we're writing an elevator to space, and you're 160 00:09:07,840 --> 00:09:11,559 Speaker 1: probably wondering, how do you build an elevator to space. 161 00:09:11,920 --> 00:09:14,079 Speaker 1: We'll get to that in a minute, but first we're 162 00:09:14,080 --> 00:09:24,520 Speaker 1: going to make another stop right about now. Okay, right now, 163 00:09:24,600 --> 00:09:28,800 Speaker 1: we are one thousand kilometers above the surface of the Earth, 164 00:09:30,000 --> 00:09:33,640 Speaker 1: which is twelve hundred times higher than the tallest building 165 00:09:33,679 --> 00:09:37,440 Speaker 1: in the world, the Birch Khalifa. So you can imagine 166 00:09:37,440 --> 00:09:40,080 Speaker 1: to get to where we are, you'd have to stag 167 00:09:40,360 --> 00:09:44,200 Speaker 1: twelve hundred of the tallest building on Earth, one on 168 00:09:44,320 --> 00:09:47,320 Speaker 1: top of the other. At this height, we are still 169 00:09:47,400 --> 00:09:51,280 Speaker 1: technically in Earth's atmosphere, but we're in the last layer, 170 00:09:51,600 --> 00:09:55,200 Speaker 1: which is the exosphere. Below us, you can see the 171 00:09:55,280 --> 00:09:58,200 Speaker 1: northern lights and there's almost no air. 172 00:09:59,400 --> 00:09:59,600 Speaker 3: Now. 173 00:10:00,040 --> 00:10:04,800 Speaker 1: About five hundred kilometers below us, we passed the International 174 00:10:04,880 --> 00:10:08,199 Speaker 1: Space Station and you might be wondering, or hey, why 175 00:10:08,280 --> 00:10:10,920 Speaker 1: didn't you stop the elevator. You could have just hopped 176 00:10:10,920 --> 00:10:15,160 Speaker 1: off and boarded the space station. Uh not really. That's 177 00:10:15,200 --> 00:10:20,240 Speaker 1: because the International Space Station zip past us at seventeen thousand, 178 00:10:20,440 --> 00:10:24,320 Speaker 1: four hundred miles per hour, which is about eight times 179 00:10:24,360 --> 00:10:28,280 Speaker 1: faster than a rifle bullet. The International Space Station has 180 00:10:28,320 --> 00:10:31,040 Speaker 1: to go that fast in order to stay in orbit. 181 00:10:31,720 --> 00:10:34,120 Speaker 1: If we were to step off this elevator right now, 182 00:10:34,480 --> 00:10:37,480 Speaker 1: you'd still fall straight down. The force of gravity right 183 00:10:37,480 --> 00:10:40,360 Speaker 1: now is still about seventy five percent of what it 184 00:10:40,480 --> 00:10:43,360 Speaker 1: is on Earth, so we feel a little lighter, but 185 00:10:43,480 --> 00:10:46,840 Speaker 1: you still definitely have your feet planet on the elevator floor. 186 00:10:47,360 --> 00:10:47,560 Speaker 3: Now. 187 00:10:47,640 --> 00:10:51,720 Speaker 1: The reason we stopped here was to pick up another passenger. Ope, 188 00:10:51,840 --> 00:10:57,320 Speaker 1: here he is, Hey, doctor Wright, did you take an 189 00:10:57,400 --> 00:10:58,560 Speaker 1: uber up here? Uh? 190 00:10:58,679 --> 00:10:59,400 Speaker 3: No, I don't think so. 191 00:11:00,240 --> 00:11:01,920 Speaker 1: Okay, I want to ask you how you got here. 192 00:11:02,000 --> 00:11:03,240 Speaker 1: But thanks for joining us. 193 00:11:03,400 --> 00:11:05,120 Speaker 3: You're welcome, happy you could have me on. 194 00:11:05,240 --> 00:11:06,680 Speaker 1: Can you please tell us who you are and what 195 00:11:06,720 --> 00:11:07,079 Speaker 1: do you do. 196 00:11:07,320 --> 00:11:10,559 Speaker 3: I'm currently serving as the president of the International Space 197 00:11:10,600 --> 00:11:14,080 Speaker 3: Elevator Consortium, which is basically a group of people who 198 00:11:14,160 --> 00:11:16,880 Speaker 3: want to advance the development of the space Elevator and 199 00:11:17,120 --> 00:11:20,400 Speaker 3: hopefully get it built within our lifetimes. We talk to 200 00:11:20,559 --> 00:11:23,920 Speaker 3: people who do calculations for the space elevator, we talk 201 00:11:23,960 --> 00:11:27,400 Speaker 3: to people who develop materials for it, and basically anybody 202 00:11:27,440 --> 00:11:31,280 Speaker 3: who might be interested in investing in it and promoting 203 00:11:31,280 --> 00:11:31,960 Speaker 3: its construction. 204 00:11:32,520 --> 00:11:34,680 Speaker 1: Great, hold on, let me press the button for the 205 00:11:34,679 --> 00:11:37,960 Speaker 1: next top, which is going to be thirty five thousand, 206 00:11:38,320 --> 00:11:41,560 Speaker 1: seven hundred and eighty six kilometers from the surface of 207 00:11:41,559 --> 00:11:47,560 Speaker 1: the Earth. We'll explain why we're going to that height 208 00:11:47,679 --> 00:11:50,320 Speaker 1: in a minute. But docked right, I want to ask 209 00:11:50,360 --> 00:11:53,920 Speaker 1: you most people listening probably assume that to build a 210 00:11:53,960 --> 00:11:57,000 Speaker 1: space elevator like the one we're writing right now, you 211 00:11:57,080 --> 00:11:59,679 Speaker 1: have to build it from the ground up, like you 212 00:11:59,760 --> 00:12:02,680 Speaker 1: start building a base on Earth, and you just keep 213 00:12:02,720 --> 00:12:05,000 Speaker 1: building up higher and higher and higher. 214 00:12:05,600 --> 00:12:09,559 Speaker 3: Yeah, pretty much, the ground up way is impractical. So 215 00:12:09,880 --> 00:12:12,720 Speaker 3: Konstantin Sarkowski he came up with the idea of building 216 00:12:12,760 --> 00:12:15,520 Speaker 3: a tower. He was thinking that of a rigid structure 217 00:12:15,920 --> 00:12:19,360 Speaker 3: fixed to the equator, and he figured, well, if you 218 00:12:19,360 --> 00:12:21,440 Speaker 3: build it high enough, yeah, you can get something into 219 00:12:21,520 --> 00:12:24,320 Speaker 3: orbit that way, and it would be very efficient. 220 00:12:24,280 --> 00:12:29,080 Speaker 1: Right, like basically building a super gigantic Eiffel tower, or 221 00:12:29,200 --> 00:12:33,280 Speaker 1: like a Birch Khalifa. But on steroids. But that wouldn't work, right, Like, 222 00:12:33,600 --> 00:12:36,440 Speaker 1: you can't build a tower that tall exactly. 223 00:12:36,960 --> 00:12:39,680 Speaker 3: He realized that would not be practical because he was 224 00:12:39,679 --> 00:12:42,520 Speaker 3: thinking of a compressive structure, in other words, a tower 225 00:12:42,920 --> 00:12:47,360 Speaker 3: based on Earth, and so calculating the strength of steel 226 00:12:47,600 --> 00:12:51,079 Speaker 3: and the mass of such a long structure it would 227 00:12:51,080 --> 00:12:53,120 Speaker 3: take I think he estimated the mass of all the 228 00:12:53,160 --> 00:12:54,360 Speaker 3: steel in the Solar System. 229 00:12:54,800 --> 00:12:57,240 Speaker 1: Okay, what doctor Wright is saying here is that to 230 00:12:57,280 --> 00:13:00,520 Speaker 1: build a space elevator you can't build it from the 231 00:13:00,559 --> 00:13:04,000 Speaker 1: ground up. That's because at some point the weight of 232 00:13:04,040 --> 00:13:07,439 Speaker 1: the tower is too much and the whole thing which 233 00:13:07,559 --> 00:13:10,320 Speaker 1: just collapse. You'd have to build a structure that is 234 00:13:10,400 --> 00:13:14,240 Speaker 1: so ginormous you would use up all the steel in 235 00:13:14,280 --> 00:13:18,920 Speaker 1: the Solar System, which is impossible. So then how do 236 00:13:18,960 --> 00:13:20,840 Speaker 1: you build a space elevator? 237 00:13:21,559 --> 00:13:24,800 Speaker 3: The way we like to think of deploying it is 238 00:13:24,880 --> 00:13:28,560 Speaker 3: starting with something in orbit. In geosynchronis orbit sending a 239 00:13:28,559 --> 00:13:31,560 Speaker 3: cable down until you have a cable that reaches the Earth. 240 00:13:31,720 --> 00:13:34,439 Speaker 1: In other words, the way to build a space elevator 241 00:13:34,840 --> 00:13:39,000 Speaker 1: is from the top down. But how do you do that? 242 00:13:40,840 --> 00:13:45,439 Speaker 1: And that brings us to our next stop. We are 243 00:13:45,520 --> 00:13:50,680 Speaker 1: now thirty five thousand, seven hundred and eighty six kilometers 244 00:13:50,920 --> 00:13:53,960 Speaker 1: from the surface of the Earth. In other words, we 245 00:13:54,080 --> 00:13:58,160 Speaker 1: are standing on the equivalent of forty three thousand, one 246 00:13:58,240 --> 00:14:03,000 Speaker 1: hundred and fifteen birds, which khaliphas stacked one on top 247 00:14:03,080 --> 00:14:06,040 Speaker 1: of the other. At this point, we are about three 248 00:14:06,280 --> 00:14:10,360 Speaker 1: earth diameters away from the surface of Earth and about 249 00:14:10,400 --> 00:14:12,880 Speaker 1: a tenth of the way to the Moon. If you 250 00:14:12,920 --> 00:14:16,160 Speaker 1: look down, you'd see the whole Earth about the size 251 00:14:16,200 --> 00:14:20,240 Speaker 1: of a basketball held at arm's length. Now, why do 252 00:14:20,400 --> 00:14:23,200 Speaker 1: we make a stop here. The reason is that at 253 00:14:23,200 --> 00:14:29,080 Speaker 1: this distance from Earth, you fall into a geosynchronous orbit. Look, 254 00:14:29,080 --> 00:14:31,480 Speaker 1: you're right, Can you explain that for us? 255 00:14:31,960 --> 00:14:34,840 Speaker 3: So this is a particular kind of orbit in which 256 00:14:34,960 --> 00:14:38,360 Speaker 3: the object in the orbit at that altitude seems to 257 00:14:38,720 --> 00:14:40,960 Speaker 3: keep the same position over the Earth when you're at 258 00:14:41,000 --> 00:14:46,080 Speaker 3: the equator. So essentially, the velocity at geosynchronous orbit is 259 00:14:46,120 --> 00:14:48,520 Speaker 3: the same as the angular velocity at the Earth, and 260 00:14:48,560 --> 00:14:50,680 Speaker 3: it would just look like it's staying there. In fact, 261 00:14:50,840 --> 00:14:53,000 Speaker 3: it's really moving at a pretty significant clip. 262 00:14:54,200 --> 00:14:57,440 Speaker 1: Okay, Remember I told you that the International Space Station, 263 00:14:57,880 --> 00:15:00,800 Speaker 1: which was in orbit about four hundred klumter from Earth, 264 00:15:01,080 --> 00:15:04,600 Speaker 1: had to go at about seventeen thousand miles per hour 265 00:15:04,880 --> 00:15:08,360 Speaker 1: to stay in orbit, otherwise it would just crash down 266 00:15:08,400 --> 00:15:11,800 Speaker 1: to Earth. Well, as you go further away from Earth, 267 00:15:12,120 --> 00:15:16,520 Speaker 1: that speed gets slower and slower, and at some point 268 00:15:16,720 --> 00:15:18,920 Speaker 1: the speed you have to keep to stay in orbit 269 00:15:19,320 --> 00:15:22,720 Speaker 1: it's the same speed as the rotation of the Earth, 270 00:15:23,440 --> 00:15:28,640 Speaker 1: and that orbit at that altitude is called the geosynchronous orbit. 271 00:15:29,240 --> 00:15:32,600 Speaker 1: So the Earth is rotating and we're flying around the Earth, 272 00:15:32,960 --> 00:15:35,840 Speaker 1: but it looks like we're just floating because the two 273 00:15:35,960 --> 00:15:40,040 Speaker 1: speeds match each other, and so we're always above the 274 00:15:40,160 --> 00:15:43,680 Speaker 1: same spot on Earth. Okay, I think you know where 275 00:15:43,720 --> 00:15:46,280 Speaker 1: this is going. What happens next, doctor B. 276 00:15:48,120 --> 00:15:50,320 Speaker 2: And So the idea of a space elevator is if 277 00:15:50,320 --> 00:15:53,480 Speaker 2: you put like a really big spool of cable right 278 00:15:53,560 --> 00:15:56,440 Speaker 2: at that geosynchronous altitude and just sort of let it 279 00:15:56,480 --> 00:16:00,440 Speaker 2: down very gradually and slowly, it would just come all 280 00:16:00,440 --> 00:16:02,880 Speaker 2: the way down to the surface of the Earth, and 281 00:16:02,920 --> 00:16:05,080 Speaker 2: you could just tie it down and have a very 282 00:16:05,240 --> 00:16:08,040 Speaker 2: long cable which you can then run some mechanical device 283 00:16:08,120 --> 00:16:10,360 Speaker 2: up to get things up into geosynchronous orbit. 284 00:16:10,920 --> 00:16:13,240 Speaker 1: It's like if you were trying to build an elevator 285 00:16:13,280 --> 00:16:15,680 Speaker 1: to a cloud. One way to do it is to 286 00:16:15,720 --> 00:16:19,880 Speaker 1: build a huge tower from the ground that reaches the cloud, 287 00:16:20,200 --> 00:16:22,800 Speaker 1: or you could just fly a balloon up to the 288 00:16:22,800 --> 00:16:26,480 Speaker 1: cloud and once you're there, lower a rope or a 289 00:16:26,560 --> 00:16:29,760 Speaker 1: cable down to the ground and use that to climb 290 00:16:29,880 --> 00:16:33,239 Speaker 1: up to the cloud. The idea for this space elevator 291 00:16:33,560 --> 00:16:37,320 Speaker 1: is the same, except instead of a balloon, you're putting 292 00:16:37,320 --> 00:16:40,160 Speaker 1: something in geosynchronous orbit. 293 00:16:40,520 --> 00:16:43,520 Speaker 3: And then you have this straight or mostly straight cable 294 00:16:43,560 --> 00:16:45,520 Speaker 3: that goes from the surface of the Earth, so it's 295 00:16:45,520 --> 00:16:50,400 Speaker 3: a big stationary cable. And on this cable you would 296 00:16:50,440 --> 00:16:53,960 Speaker 3: put a climber or an elevator car or something which 297 00:16:54,040 --> 00:16:57,160 Speaker 3: lifts your payload up to whatever altitude you want. 298 00:16:57,760 --> 00:17:00,280 Speaker 1: And at this distance from Earth, if you s depth 299 00:17:00,320 --> 00:17:04,560 Speaker 1: outside the elevator, you would just float. You wouldn't fall 300 00:17:04,600 --> 00:17:07,800 Speaker 1: back down because the gravity would be weaker, and it 301 00:17:07,840 --> 00:17:11,760 Speaker 1: would exactly match this interpretal force you get from going 302 00:17:11,840 --> 00:17:15,119 Speaker 1: in a circle around the Earth. And the idea is 303 00:17:15,119 --> 00:17:17,960 Speaker 1: that at this point you could bring materials up to 304 00:17:18,000 --> 00:17:21,879 Speaker 1: the elevator and build a whole city up there in space. 305 00:17:22,600 --> 00:17:24,000 Speaker 3: So there are a lot of things we can do. 306 00:17:24,480 --> 00:17:27,800 Speaker 3: So that's a perfect place to build solar power satellites. 307 00:17:28,080 --> 00:17:32,080 Speaker 3: Rather large habitats could be built there. Okay, colonies things 308 00:17:32,160 --> 00:17:33,879 Speaker 3: like that, orbibal factories. 309 00:17:36,040 --> 00:17:38,359 Speaker 1: Okay, when we come back, we're going to talk about 310 00:17:38,480 --> 00:17:41,879 Speaker 1: another really cool thing you can do with a space elevator, 311 00:17:42,200 --> 00:17:45,000 Speaker 1: and we're going to answer the question you're probably thinking 312 00:17:45,280 --> 00:17:49,280 Speaker 1: right now, which is why haven't we built them? If 313 00:17:49,320 --> 00:17:52,679 Speaker 1: space elevators are so great, why are we still sending 314 00:17:52,720 --> 00:17:56,760 Speaker 1: things to space using rockets? Well, answer that question after 315 00:17:56,920 --> 00:18:09,240 Speaker 1: the break. You're listening to science stuff and we're back. Okay, 316 00:18:09,600 --> 00:18:13,399 Speaker 1: you and I are currently in space thirty five thousand, 317 00:18:13,720 --> 00:18:17,800 Speaker 1: seven hundred and eighty six kilometers above the surface of 318 00:18:17,840 --> 00:18:22,600 Speaker 1: the Earth. At this point, we are definitely outside Earth's atmosphere. 319 00:18:22,920 --> 00:18:25,800 Speaker 1: We left that at ten thousand kilometers, but we're still 320 00:18:25,880 --> 00:18:31,040 Speaker 1: under the influence of Earth's gravity barely. At this height 321 00:18:31,119 --> 00:18:34,879 Speaker 1: and at this speed, we are logged in geosynchronous orbit, 322 00:18:35,320 --> 00:18:38,600 Speaker 1: which means we're always above the same point on the 323 00:18:38,680 --> 00:18:42,640 Speaker 1: surface of Earth as it rotates. And I should mention 324 00:18:42,840 --> 00:18:46,960 Speaker 1: this only works of our orbit goes around Earth's equator. Now, 325 00:18:47,000 --> 00:18:49,199 Speaker 1: if we were to lower a cable down to the 326 00:18:49,240 --> 00:18:52,440 Speaker 1: surface of Earth thirty five thousand, seven hundred and eighty 327 00:18:52,480 --> 00:18:56,520 Speaker 1: six kilometers, we would create a link between us and 328 00:18:56,720 --> 00:19:00,800 Speaker 1: Earth that we could use as an elevator. You could 329 00:19:00,800 --> 00:19:04,160 Speaker 1: attach a platform that climbs up the cable to bring 330 00:19:04,240 --> 00:19:08,880 Speaker 1: things to space without having to use expensive, dangerous and 331 00:19:08,960 --> 00:19:14,199 Speaker 1: polluting rockets. That's the idea of a space elevator. And 332 00:19:14,240 --> 00:19:16,119 Speaker 1: what school is that you can use it not just 333 00:19:16,160 --> 00:19:19,480 Speaker 1: to put things in space, but to fling them to 334 00:19:19,720 --> 00:19:21,919 Speaker 1: other planets, right the repete. 335 00:19:22,200 --> 00:19:25,400 Speaker 2: Yeah, And the final argument that people put forward is 336 00:19:25,440 --> 00:19:29,880 Speaker 2: that you know, there's this balance between centripetal and gravitational acceleration, 337 00:19:30,680 --> 00:19:33,840 Speaker 2: and when you're in geosynchronous they're precisely balanced and you're 338 00:19:34,000 --> 00:19:38,520 Speaker 2: precisely above the Earth. But everything beyond that centripetal acceleration 339 00:19:38,640 --> 00:19:42,120 Speaker 2: is actually larger than gravitational force. So if you run 340 00:19:42,160 --> 00:19:45,320 Speaker 2: a cable beyond the space elevator, if you run some 341 00:19:45,400 --> 00:19:48,720 Speaker 2: kind of structure beyond the space elevator, at some point, 342 00:19:48,880 --> 00:19:52,280 Speaker 2: if you go an additional three thousand kilometers, that tip 343 00:19:52,600 --> 00:19:55,920 Speaker 2: the apex of the space elevator is actually moving faster 344 00:19:56,400 --> 00:19:59,320 Speaker 2: than the velocity you need to escape the Earth's gravitational influence, 345 00:19:59,359 --> 00:20:00,680 Speaker 2: so you could go to other planets. 346 00:20:02,119 --> 00:20:04,840 Speaker 1: Okay, this is pretty cool. So where we are now 347 00:20:05,040 --> 00:20:09,040 Speaker 1: in geosynchronous orbit, it's sort of perfectly balanced. But if 348 00:20:09,080 --> 00:20:12,359 Speaker 1: I were to extend the space elevator further out, like 349 00:20:12,600 --> 00:20:15,040 Speaker 1: if I were to not just drop a cable down 350 00:20:15,080 --> 00:20:17,760 Speaker 1: to Earth, but also let loose a cable the other 351 00:20:17,840 --> 00:20:21,480 Speaker 1: way away from Earth, you could use that cable to 352 00:20:21,680 --> 00:20:26,159 Speaker 1: fling things out into space. So, for example, if I 353 00:20:26,200 --> 00:20:29,600 Speaker 1: attach a dumbbell to that cable above us, we would 354 00:20:29,640 --> 00:20:33,000 Speaker 1: see that dumbell start moving away from us because of 355 00:20:33,160 --> 00:20:37,240 Speaker 1: centripetal acceleration. That's the force that pushes you out when 356 00:20:37,520 --> 00:20:40,159 Speaker 1: say you're going around a Narry go round, or the 357 00:20:40,160 --> 00:20:42,760 Speaker 1: force that pulls your arms out if you spin in place. 358 00:20:43,520 --> 00:20:46,720 Speaker 1: So we'd see the dumbbell move away from us, going 359 00:20:46,840 --> 00:20:50,439 Speaker 1: faster and faster, and then if the cable ends, the 360 00:20:50,520 --> 00:20:54,359 Speaker 1: dumbo would get flung out into space. And that's how 361 00:20:54,400 --> 00:20:57,560 Speaker 1: you can use a space elevator to launch things to 362 00:20:57,760 --> 00:20:58,800 Speaker 1: other planets. 363 00:21:00,440 --> 00:21:02,760 Speaker 3: Yeah, you could let it go off the end of 364 00:21:02,800 --> 00:21:06,560 Speaker 3: the cable and that would have its maximum release velocity. 365 00:21:06,640 --> 00:21:10,080 Speaker 3: So if you release at one hundred thousand kilometers, then 366 00:21:10,119 --> 00:21:12,520 Speaker 3: you can reach the inner edge of the asteroid belt 367 00:21:12,640 --> 00:21:16,720 Speaker 3: without any extra rocket thrust. If you want to go 368 00:21:16,760 --> 00:21:21,280 Speaker 3: to Mars, you can release at that altitude or a 369 00:21:21,320 --> 00:21:24,120 Speaker 3: lower one. But if you release at that altitude, then 370 00:21:24,160 --> 00:21:26,639 Speaker 3: you can get to Mars in about sixty one days 371 00:21:26,640 --> 00:21:29,480 Speaker 3: as oppose to you know, they're talking about one hundred 372 00:21:29,480 --> 00:21:31,280 Speaker 3: and eighty days for a typical mission. 373 00:21:31,680 --> 00:21:35,320 Speaker 2: Exactly, you wouldn't need any rockets at all. Presumably once 374 00:21:35,320 --> 00:21:37,399 Speaker 2: you got to Jupiter, you wouldn't want to like crash 375 00:21:37,440 --> 00:21:39,719 Speaker 2: into one of the moons, so there'd have to be 376 00:21:39,720 --> 00:21:42,680 Speaker 2: some aerobraking, or you might want to like have a 377 00:21:42,760 --> 00:21:44,480 Speaker 2: rocket to slow down at some point. 378 00:21:44,640 --> 00:21:48,320 Speaker 1: Yeah, so this space elevator wouldn't just get you to space. 379 00:21:48,720 --> 00:21:50,960 Speaker 1: If you want to, say, live in a space station 380 00:21:51,160 --> 00:21:56,280 Speaker 1: in geosynchronous orbit, you could also sling you to other planets. Okay, 381 00:21:56,280 --> 00:21:59,720 Speaker 1: you're probably thinking, now this sounds great, Jorge, but why 382 00:21:59,760 --> 00:22:02,440 Speaker 1: haven't we built one? What's the catch? 383 00:22:03,080 --> 00:22:03,199 Speaker 3: All? 384 00:22:03,280 --> 00:22:07,760 Speaker 1: Right, there are two caveats. The first one comes if 385 00:22:07,760 --> 00:22:10,639 Speaker 1: you think about where the energy is coming from in 386 00:22:10,720 --> 00:22:13,720 Speaker 1: a space elevator. I mean, you get to put things 387 00:22:13,720 --> 00:22:16,720 Speaker 1: in space and even fling them to other planets without 388 00:22:16,840 --> 00:22:21,000 Speaker 1: needing rockets. It sounds too good to be true, doesn't it, 389 00:22:21,040 --> 00:22:21,760 Speaker 1: doctor Pete. 390 00:22:22,040 --> 00:22:26,280 Speaker 2: Yeah, now that's a great insight. So there's no free launch, 391 00:22:26,359 --> 00:22:29,680 Speaker 2: I guess, But weird things happen in space because it's 392 00:22:29,680 --> 00:22:34,200 Speaker 2: an energy conserving field, So where is the energy coming from. 393 00:22:34,320 --> 00:22:38,040 Speaker 2: It's interesting because once you get beyond geosynchronous, the acceleration 394 00:22:38,200 --> 00:22:41,080 Speaker 2: to get to the velocity to get to Jupiter is 395 00:22:41,480 --> 00:22:45,640 Speaker 2: coming from actually the rotational inertia of the Earth itself. 396 00:22:46,119 --> 00:22:49,760 Speaker 2: So the Earth is spinning and pulling the space Elevator 397 00:22:49,800 --> 00:22:53,960 Speaker 2: along with it, and so that acceleration is transferred to 398 00:22:54,000 --> 00:22:56,720 Speaker 2: the base of the space Elevator, and every launch would 399 00:22:57,080 --> 00:23:00,359 Speaker 2: very slightly slow down the spin of the Earth. So 400 00:23:00,520 --> 00:23:03,879 Speaker 2: presumably we wouldn't launch too much or people would have 401 00:23:03,920 --> 00:23:08,120 Speaker 2: to adjust their atomic clocks eventually, but I don't think 402 00:23:08,119 --> 00:23:09,040 Speaker 2: we'd get to that point. 403 00:23:09,200 --> 00:23:12,280 Speaker 1: The day would get longer eventually if we launch enough things, the. 404 00:23:12,320 --> 00:23:14,920 Speaker 2: Day would slightly longer eventually if we launch it enough. 405 00:23:14,760 --> 00:23:16,919 Speaker 1: Stuff That doesn't sound good for the planet. 406 00:23:18,240 --> 00:23:20,560 Speaker 2: Well, if you compared it to the amount of rocket 407 00:23:20,560 --> 00:23:22,560 Speaker 2: fuel we would have to burn in order to do 408 00:23:22,640 --> 00:23:25,480 Speaker 2: the same thing, I think we could make an environmental 409 00:23:25,520 --> 00:23:26,040 Speaker 2: case for this. 410 00:23:26,520 --> 00:23:30,159 Speaker 1: So basically, if we use the space Elevator too much, 411 00:23:30,640 --> 00:23:35,359 Speaker 1: we would slow down the earth rotation. Now, the Earth 412 00:23:35,440 --> 00:23:38,879 Speaker 1: is huge and massive, so we would barely affect it 413 00:23:39,240 --> 00:23:42,280 Speaker 1: and besides, who wouldn't mind having a few extra minutes 414 00:23:42,280 --> 00:23:45,600 Speaker 1: of time each day? And the other caveat is a 415 00:23:45,600 --> 00:23:48,760 Speaker 1: big one. You've probably been wondering why how would we 416 00:23:48,760 --> 00:23:51,960 Speaker 1: build a space elevator, And the answer is that it's 417 00:23:52,040 --> 00:23:56,960 Speaker 1: really hard to make. Remember how we're thirty five seven 418 00:23:57,040 --> 00:24:00,520 Speaker 1: hundred and eighty six kilometers above Earth, and to make 419 00:24:00,560 --> 00:24:03,440 Speaker 1: a space elevator you have to lower a cable down 420 00:24:03,480 --> 00:24:06,760 Speaker 1: to the surface thirty five seven hundred and eighty six 421 00:24:06,840 --> 00:24:11,679 Speaker 1: kilometers below. That's a lot of cable. If you were 422 00:24:11,720 --> 00:24:15,040 Speaker 1: to hang down a steel cable that long, at some point, 423 00:24:15,600 --> 00:24:18,919 Speaker 1: the weight of the cable itself being pulled down by 424 00:24:18,960 --> 00:24:22,400 Speaker 1: the Earth would break the cable. And if you try 425 00:24:22,400 --> 00:24:24,840 Speaker 1: to make the cable thicker to make it stronger, that 426 00:24:24,880 --> 00:24:28,000 Speaker 1: would just make the cable heavier and it would still break. 427 00:24:28,760 --> 00:24:32,120 Speaker 1: It's like imagine trying to hang a long, long strand 428 00:24:32,160 --> 00:24:36,240 Speaker 1: of cook spaghetti off the side of a building. At 429 00:24:36,240 --> 00:24:39,720 Speaker 1: some point, the amount of spaghetti hanging would weigh so 430 00:24:39,880 --> 00:24:43,359 Speaker 1: much you would break the spaghetti at the top, which 431 00:24:43,400 --> 00:24:47,520 Speaker 1: is holding all the weight. Scientists have calculated that basically 432 00:24:47,800 --> 00:24:52,040 Speaker 1: it's not really possible to make a single space elevator 433 00:24:52,080 --> 00:24:56,639 Speaker 1: cable that would work for materials we currently have, but 434 00:24:57,119 --> 00:25:01,159 Speaker 1: that doesn't mean it's impossible. One postle idea is to 435 00:25:01,280 --> 00:25:03,680 Speaker 1: use carbon nanotubes. 436 00:25:06,119 --> 00:25:10,560 Speaker 3: In nineteen ninety one, the carbon nanotubes were discovered, and 437 00:25:10,600 --> 00:25:13,720 Speaker 3: that was really the first material that was ever demonstrated 438 00:25:13,760 --> 00:25:16,840 Speaker 3: to have the sufficiently high strength and blow a mass 439 00:25:16,880 --> 00:25:19,760 Speaker 3: at the same time. Okay, that you could conceive of 440 00:25:19,800 --> 00:25:22,800 Speaker 3: building a tether that would support itself. Since then, there 441 00:25:22,840 --> 00:25:26,520 Speaker 3: have been other discoveries of materials. One is graphene, and 442 00:25:26,760 --> 00:25:29,679 Speaker 3: there's a third candidate called texagonal boron nitride. 443 00:25:30,040 --> 00:25:34,800 Speaker 1: These materials could potentially work, except we still haven't figured 444 00:25:34,840 --> 00:25:38,640 Speaker 1: out how to really make them. They're still very experimental. 445 00:25:39,160 --> 00:25:43,160 Speaker 1: And the other possible solution is to use carbon fibers 446 00:25:43,200 --> 00:25:45,720 Speaker 1: in the shape of a thirty five thousand, seven hundred 447 00:25:45,720 --> 00:25:50,480 Speaker 1: and eighty six kilometer tall inverted Eiffel Tower. 448 00:25:51,200 --> 00:25:55,159 Speaker 2: I would use a carbon fiber because it's well understood 449 00:25:55,400 --> 00:25:58,480 Speaker 2: and reliable, and then I would go from like one 450 00:25:58,520 --> 00:26:04,480 Speaker 2: cable at kilometers to three cables, and then five cables, 451 00:26:04,640 --> 00:26:06,439 Speaker 2: and then you know, just multiply the number of. 452 00:26:06,480 --> 00:26:09,000 Speaker 1: Cables because you just kind of like breed more cables 453 00:26:09,040 --> 00:26:09,840 Speaker 1: in as you go up. 454 00:26:10,040 --> 00:26:11,800 Speaker 2: So you can think of it as a really big 455 00:26:11,960 --> 00:26:15,000 Speaker 2: slag tight it's like very thick at the top and 456 00:26:15,040 --> 00:26:19,320 Speaker 2: then tapers down because all of that force has to 457 00:26:19,359 --> 00:26:23,480 Speaker 2: be structurally supported. So in practice, you'd have a very 458 00:26:23,520 --> 00:26:26,439 Speaker 2: thick cable at the geosynchronous and a very thin cable 459 00:26:26,680 --> 00:26:27,920 Speaker 2: at the surface of the Earth. 460 00:26:28,160 --> 00:26:30,639 Speaker 1: And the math works out like, he'll stay, I'll hold 461 00:26:30,800 --> 00:26:33,560 Speaker 1: that would work. How thick would the cable need to 462 00:26:33,560 --> 00:26:34,040 Speaker 1: be at the top? 463 00:26:34,240 --> 00:26:36,040 Speaker 2: I have not done the math on that one, but 464 00:26:37,040 --> 00:26:41,280 Speaker 2: I would estimate that it would probably be on the 465 00:26:41,400 --> 00:26:44,160 Speaker 2: order of one hundred meters still, which is not that big. 466 00:26:44,200 --> 00:26:46,560 Speaker 2: I mean, we have some spy satellites up in space 467 00:26:46,600 --> 00:26:48,640 Speaker 2: which have a radius of one hundred meters. 468 00:26:49,080 --> 00:26:52,160 Speaker 1: Okay, that sounds pretty good. What's the problem. 469 00:26:52,440 --> 00:26:56,200 Speaker 2: So creating a huge stalactite in space requires a great 470 00:26:56,200 --> 00:26:57,960 Speaker 2: deal of material and how do you get it up there? 471 00:26:58,480 --> 00:27:00,520 Speaker 2: And the answer is you have to strock it to 472 00:27:00,560 --> 00:27:01,200 Speaker 2: get it up there? 473 00:27:01,600 --> 00:27:04,280 Speaker 1: Oh wow, yeah, So I mean it would be super 474 00:27:04,400 --> 00:27:07,000 Speaker 1: duper expensive. At the beginning, you're saying. 475 00:27:07,080 --> 00:27:10,240 Speaker 2: Yeah, so there are people that study the economics of this, 476 00:27:10,320 --> 00:27:12,200 Speaker 2: and I think they're talking like a trillion dollars or 477 00:27:12,240 --> 00:27:13,200 Speaker 2: something like that. 478 00:27:13,200 --> 00:27:14,120 Speaker 1: That seems doable. 479 00:27:14,520 --> 00:27:17,040 Speaker 2: Oh, it's doable. Yeah. I mean the question is do 480 00:27:17,080 --> 00:27:20,240 Speaker 2: you have an economic case for doing so? Right? That's yeah, 481 00:27:20,280 --> 00:27:21,480 Speaker 2: that's a real question. 482 00:27:22,320 --> 00:27:25,480 Speaker 1: All right. I think that's the end of our elevator 483 00:27:25,560 --> 00:27:29,280 Speaker 1: right today. To recap, a space elevator would be a 484 00:27:29,320 --> 00:27:33,280 Speaker 1: more efficient and more environmentally friendly way to get to 485 00:27:33,440 --> 00:27:37,560 Speaker 1: space and beyond if we can figure out how to 486 00:27:37,600 --> 00:27:41,600 Speaker 1: hang a thirty five, seven hundred and eighty six kilometer 487 00:27:41,760 --> 00:27:46,560 Speaker 1: long cable from geosynchronous orbit. So the next time you 488 00:27:46,560 --> 00:27:49,239 Speaker 1: look up at this guy, try to imagine us in 489 00:27:49,240 --> 00:27:53,080 Speaker 1: this elevator car dreaming of pushing a button and getting 490 00:27:53,080 --> 00:27:56,720 Speaker 1: a lift into space. Okay, I just have one last 491 00:27:56,800 --> 00:28:00,560 Speaker 1: question for our experts. Last question is someone it's a 492 00:28:00,680 --> 00:28:03,159 Speaker 1: space elevator, what kind of music would you put in it? 493 00:28:06,400 --> 00:28:08,760 Speaker 3: Believe it or not. There's a British band called Space 494 00:28:08,840 --> 00:28:12,119 Speaker 3: Elevator and I don't know how you characterize their music, 495 00:28:12,160 --> 00:28:14,159 Speaker 3: but it is something different. 496 00:28:14,960 --> 00:28:17,000 Speaker 1: Well, it sounds like this band would by definition be 497 00:28:17,119 --> 00:28:18,240 Speaker 1: space elevator music. 498 00:28:18,440 --> 00:28:19,920 Speaker 3: That's what we were thinking. Yeah. 499 00:28:20,000 --> 00:28:23,760 Speaker 2: Well, Johannes Kepler, who discovered orbits and is sort of 500 00:28:23,760 --> 00:28:26,439 Speaker 2: one of my heroes, was also a very mystical person 501 00:28:26,480 --> 00:28:30,800 Speaker 2: and tried to design music based on the geometric relationships 502 00:28:30,800 --> 00:28:33,200 Speaker 2: of the planets in the sun, what you called the 503 00:28:33,280 --> 00:28:37,679 Speaker 2: music of the spheres. So it's not particularly good music, 504 00:28:37,960 --> 00:28:41,080 Speaker 2: but then most elevator music isn't very good anyway. 505 00:28:40,840 --> 00:28:44,200 Speaker 1: So thanks for taking a ride with us. See you 506 00:28:44,200 --> 00:28:50,520 Speaker 1: next time. Hey, if you like to join the movement 507 00:28:50,600 --> 00:28:53,640 Speaker 1: to get space elevators made, doctor Wright would like you 508 00:28:53,720 --> 00:28:59,360 Speaker 1: to visit the International Space Elevator Consortium website at ISEC 509 00:29:01,680 --> 00:29:05,120 Speaker 1: you've been listening to Science Stuff the production of iHeartRadio, 510 00:29:05,520 --> 00:29:09,400 Speaker 1: written and produced by me or Heycham, edited by Rose Seguda, 511 00:29:09,840 --> 00:29:14,040 Speaker 1: executive producer Jerry Rowland, and audio engineer and mixer Kasey Peckram. 512 00:29:14,280 --> 00:29:16,479 Speaker 1: You can follow me on social media just search for 513 00:29:16,640 --> 00:29:19,760 Speaker 1: PhD Comics and the name of your favorite platform. 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