1 00:00:04,400 --> 00:00:07,800 Speaker 1: Welcome to Text Stuff, a production from my Heart Radio. 2 00:00:12,080 --> 00:00:15,240 Speaker 1: Hey there, and welcome to tech Stuff. I'm your host, 3 00:00:15,480 --> 00:00:19,360 Speaker 1: Jonathan Strickland. I'm an executive producer with I Heart Radio 4 00:00:19,480 --> 00:00:23,079 Speaker 1: and I love all things tech and today's episode is 5 00:00:23,120 --> 00:00:27,440 Speaker 1: in response to a request Carlos wrote to me and 6 00:00:27,520 --> 00:00:30,240 Speaker 1: asked me this. He said, Hey, Jonathan, great work on 7 00:00:30,280 --> 00:00:33,760 Speaker 1: your podcast. I am looking at satellite communications and I 8 00:00:33,880 --> 00:00:36,920 Speaker 1: find it hard to understand how are they used for 9 00:00:37,000 --> 00:00:40,680 Speaker 1: Internet access, why they use mega hurts instead of megabits 10 00:00:40,720 --> 00:00:43,400 Speaker 1: per second, and in general, how they communicate to Earth 11 00:00:43,720 --> 00:00:47,879 Speaker 1: perhaps a continuation episode. Well that's a great topic, and 12 00:00:47,920 --> 00:00:50,440 Speaker 1: I get how it can be confusing when a technology 13 00:00:50,520 --> 00:00:54,880 Speaker 1: uses different but similar sounding terms. So today we're going 14 00:00:54,920 --> 00:00:58,600 Speaker 1: to break down satellite communications and how they work. Now, 15 00:00:59,080 --> 00:01:01,560 Speaker 1: the simple and there to the question is that satellites 16 00:01:01,600 --> 00:01:05,200 Speaker 1: communicate using radio waves, and in fact that's where the 17 00:01:05,200 --> 00:01:08,720 Speaker 1: mega hurts stuff comes in. But that doesn't really create 18 00:01:08,800 --> 00:01:11,920 Speaker 1: an understanding of what's going on. To do that, we 19 00:01:11,959 --> 00:01:14,520 Speaker 1: need to jump into some history. And you might think 20 00:01:14,560 --> 00:01:17,400 Speaker 1: I would start with nineteen fifty seven with the first 21 00:01:17,440 --> 00:01:21,199 Speaker 1: satellite to achieve orbit, but you're wrong. We're going back 22 00:01:21,240 --> 00:01:24,839 Speaker 1: a bit further I'm going to start all the way 23 00:01:24,880 --> 00:01:29,840 Speaker 1: back in nineteen o three, which sounds crazy, right, but 24 00:01:30,440 --> 00:01:35,040 Speaker 1: that's when a Russian scientist named Konstantine Selkovsky worked out 25 00:01:35,160 --> 00:01:38,200 Speaker 1: the mass that suggested that, yeah, it would be possible 26 00:01:38,560 --> 00:01:41,520 Speaker 1: to build a rocket that we could launch from Earth 27 00:01:41,800 --> 00:01:45,720 Speaker 1: and lift a payload into space, so that that payload, 28 00:01:45,880 --> 00:01:50,040 Speaker 1: that object would be in an orbit around Earth. Now, 29 00:01:50,080 --> 00:01:54,160 Speaker 1: see gravity pulls downward, or if you prefer it, pulls 30 00:01:54,200 --> 00:01:57,560 Speaker 1: towards a center of mass, because you know, once we 31 00:01:57,560 --> 00:02:00,960 Speaker 1: get out into space, concepts like up and down don't 32 00:02:01,320 --> 00:02:05,840 Speaker 1: have so much meaning. Inertia of a moving body tends 33 00:02:05,920 --> 00:02:08,280 Speaker 1: to make it move in a in a straight line. 34 00:02:08,360 --> 00:02:11,440 Speaker 1: So think of it as we have a perfectly leveled table. 35 00:02:11,639 --> 00:02:13,360 Speaker 1: Now we've got a ball on the table, and you 36 00:02:13,440 --> 00:02:16,240 Speaker 1: give a push on the ball, it will tend to 37 00:02:16,240 --> 00:02:18,840 Speaker 1: travel in a straight line in the same direction as 38 00:02:18,919 --> 00:02:23,760 Speaker 1: your push. So if there is a balance between gravity 39 00:02:23,880 --> 00:02:27,280 Speaker 1: and inertia, an object will continue in a straight line 40 00:02:27,320 --> 00:02:31,040 Speaker 1: while being pulled toward a center of mass. So, if 41 00:02:31,040 --> 00:02:33,320 Speaker 1: the object is moving fast enough, the ground of the 42 00:02:33,360 --> 00:02:37,360 Speaker 1: Earth will curve away from its path as it falls 43 00:02:37,400 --> 00:02:40,240 Speaker 1: towards the Earth. So it's kind of in a constant 44 00:02:40,280 --> 00:02:43,320 Speaker 1: state of falling. This, by the way, is one of 45 00:02:43,520 --> 00:02:46,880 Speaker 1: many proofs that the Earth is round, because if it weren't, 46 00:02:47,320 --> 00:02:50,959 Speaker 1: orbits would not work. But we know they work because 47 00:02:50,960 --> 00:02:54,000 Speaker 1: we built stuff, we put it in orbit, We depend 48 00:02:54,040 --> 00:02:56,600 Speaker 1: on that stuff on a day to day basis, So 49 00:02:56,919 --> 00:03:00,440 Speaker 1: that alone is proof that the Earth is round. Now, 50 00:03:00,560 --> 00:03:05,000 Speaker 1: Silkovski proved that an orbiting satellite was possible from a 51 00:03:05,080 --> 00:03:08,720 Speaker 1: mathematical point of view, but there was no real, you know, 52 00:03:09,080 --> 00:03:12,600 Speaker 1: rush to prove him right. For one thing, what the 53 00:03:12,639 --> 00:03:15,640 Speaker 1: heck would the ding dang durn thing do once it 54 00:03:15,720 --> 00:03:19,160 Speaker 1: was up there? I mean, would we just be throwing 55 00:03:19,240 --> 00:03:22,480 Speaker 1: resources at something just to say we did it? I mean, 56 00:03:22,480 --> 00:03:24,919 Speaker 1: this would be the equivalent of answering the question why 57 00:03:24,960 --> 00:03:28,560 Speaker 1: do you want to climb Mount Everest with because it's there? 58 00:03:29,400 --> 00:03:32,520 Speaker 1: That might not be the best answer for all situations. Besides, 59 00:03:32,680 --> 00:03:37,280 Speaker 1: Silkowsky's work wasn't widely known for many years. In fact, 60 00:03:37,520 --> 00:03:42,040 Speaker 1: two decades later, a Romanian scientist named herman O Birth 61 00:03:43,080 --> 00:03:48,040 Speaker 1: essentially worked out the same stuff completely independently of Solkovsky's work. 62 00:03:48,040 --> 00:03:51,920 Speaker 1: He wasn't aware of Silkovsky. But again, even ober It's 63 00:03:51,960 --> 00:03:56,600 Speaker 1: work was confined to a relatively small circle of physicists, 64 00:03:56,720 --> 00:04:00,520 Speaker 1: or as the British would say, Boffin's he. Even well 65 00:04:00,640 --> 00:04:04,160 Speaker 1: read physicists in the United States had never heard of 66 00:04:04,200 --> 00:04:07,920 Speaker 1: either of these two people, and while they were all 67 00:04:07,960 --> 00:04:12,880 Speaker 1: thinking about space, none of them had actually proposed an 68 00:04:12,960 --> 00:04:18,040 Speaker 1: artificial satellite as of yet. Robert Goddard, an American, made 69 00:04:18,040 --> 00:04:21,720 Speaker 1: another important contribution to our space efforts. While pursuing post 70 00:04:21,800 --> 00:04:26,720 Speaker 1: graduate studies at Princeton University. He demonstrated that rocket propulsion 71 00:04:26,760 --> 00:04:30,719 Speaker 1: would work even in the airless environment of space, and 72 00:04:30,760 --> 00:04:34,640 Speaker 1: this was around nineteen sixteen or so, and he built 73 00:04:34,680 --> 00:04:39,039 Speaker 1: a solid fuel rocket in nineteen eighteen. But his funding 74 00:04:39,160 --> 00:04:41,960 Speaker 1: dried up around the time that World War One ended, 75 00:04:42,080 --> 00:04:44,359 Speaker 1: and this is going to be an ongoing theme in 76 00:04:44,360 --> 00:04:47,680 Speaker 1: the space industry. Scientists seem to get way more funds 77 00:04:48,279 --> 00:04:52,160 Speaker 1: when there are possible military applications to the technology they're developing, 78 00:04:52,360 --> 00:04:55,799 Speaker 1: you know, beyond just putting stuff up into space. Goddard 79 00:04:55,800 --> 00:04:59,080 Speaker 1: would continue his work through various colleges up until World 80 00:04:59,120 --> 00:05:01,640 Speaker 1: War Two, when a again he would receive funding to 81 00:05:01,680 --> 00:05:04,840 Speaker 1: work on rocketry with applications for the military, in this 82 00:05:04,920 --> 00:05:08,120 Speaker 1: case largely in the world of jet assisted takeoff or 83 00:05:08,520 --> 00:05:14,080 Speaker 1: j to j A. T O. Germany also famously pursued 84 00:05:14,160 --> 00:05:17,159 Speaker 1: rocketry in World War Two, using it to great effect 85 00:05:17,240 --> 00:05:20,839 Speaker 1: with devastating weapons like the V two rocket. One of 86 00:05:20,839 --> 00:05:24,880 Speaker 1: the scientists chiefly responsible for that V two rocket was 87 00:05:24,960 --> 00:05:29,840 Speaker 1: Werner von Braun, sort of Germany's equivalent of Goddard. Von 88 00:05:29,880 --> 00:05:34,039 Speaker 1: Braun was interested in spaceflight, but like Goddard, he put 89 00:05:34,080 --> 00:05:36,560 Speaker 1: his mind to work for a military in an effort 90 00:05:36,560 --> 00:05:41,159 Speaker 1: to fund his research. Germany used von Braun's rockets to 91 00:05:41,440 --> 00:05:45,719 Speaker 1: fire upon cities like London, killing thousands and devastating entire 92 00:05:45,800 --> 00:05:51,040 Speaker 1: sections of the city. Von Braun wasn't necessarily the most 93 00:05:51,400 --> 00:05:55,000 Speaker 1: ardent supporter of the Nazi regime during World War Two, 94 00:05:55,320 --> 00:05:57,880 Speaker 1: but he joined the Nazi Party and became a member 95 00:05:57,880 --> 00:06:00,080 Speaker 1: of the s S and while he didn't seem to 96 00:06:00,120 --> 00:06:03,440 Speaker 1: share any real political views with the Nazis, he did 97 00:06:03,520 --> 00:06:06,320 Speaker 1: see the allegiance to the party as a necessity for 98 00:06:06,400 --> 00:06:08,760 Speaker 1: him to get the resources he wanted to pursue the 99 00:06:08,800 --> 00:06:13,120 Speaker 1: goal of space flight, so to him, the ends justified 100 00:06:13,200 --> 00:06:17,480 Speaker 1: the means. In nineteen forty three, scientists working for the U. S. 101 00:06:17,560 --> 00:06:20,440 Speaker 1: Navy began to look into the possibility that the Nazis 102 00:06:20,480 --> 00:06:24,680 Speaker 1: were developing rockets capable of putting an artificial satellite into orbit. 103 00:06:25,120 --> 00:06:27,680 Speaker 1: Their worry was that a device like that might be 104 00:06:27,760 --> 00:06:31,800 Speaker 1: used for reconnaissance or spy technology, or maybe even as 105 00:06:31,800 --> 00:06:35,920 Speaker 1: a weapon, whether a weapon capable of actually creating physical 106 00:06:36,000 --> 00:06:39,960 Speaker 1: destruction or a more psychological weapon to terrorize people into 107 00:06:40,000 --> 00:06:43,599 Speaker 1: thinking they'd be subjected to death rays or something. The 108 00:06:43,680 --> 00:06:47,680 Speaker 1: scientists concluded that it could be possible to launch a 109 00:06:47,720 --> 00:06:51,040 Speaker 1: satellite into orbit. Essentially, they were retreading the ground that 110 00:06:51,120 --> 00:06:54,719 Speaker 1: Siolkovsky and o Berth had already walked, and there was 111 00:06:54,760 --> 00:06:58,520 Speaker 1: some early interest in exploring that as an actual option. 112 00:06:59,120 --> 00:07:02,839 Speaker 1: In nineteen four be four, while at a party, Von 113 00:07:02,960 --> 00:07:06,599 Speaker 1: Brown got inebriated and he let it slip that he 114 00:07:06,720 --> 00:07:09,880 Speaker 1: thought the war wouldn't end well for Germany, which was 115 00:07:09,920 --> 00:07:13,320 Speaker 1: pretty much a foregone conclusion, but it was essentially a 116 00:07:13,360 --> 00:07:16,760 Speaker 1: treasonous act. To actually suggest that Germany would lose the 117 00:07:16,800 --> 00:07:21,200 Speaker 1: war was an act of treason. So he was arrested. However, 118 00:07:21,240 --> 00:07:24,800 Speaker 1: he was never incarcerated. It did send a message to him, 119 00:07:24,960 --> 00:07:28,200 Speaker 1: you know, Von Brown said, Wow, my place here is 120 00:07:28,240 --> 00:07:30,200 Speaker 1: not as secure as I would like it to be. 121 00:07:30,800 --> 00:07:34,880 Speaker 1: So he and several other rockets scientists went into hiding. 122 00:07:35,280 --> 00:07:40,800 Speaker 1: Upon hearing that Hitler had committed suicide, these scientists surrendered 123 00:07:40,800 --> 00:07:44,160 Speaker 1: to American soldiers and they were part of a negotiation 124 00:07:44,560 --> 00:07:47,840 Speaker 1: to come to America and essentially pursue the same sort 125 00:07:47,880 --> 00:07:50,640 Speaker 1: of work they had been doing for Germany, but in 126 00:07:50,680 --> 00:07:54,520 Speaker 1: the United States. Now. This was known in classified circles 127 00:07:54,600 --> 00:07:57,800 Speaker 1: as Operation paper Clip, and it involved bringing more than 128 00:07:57,880 --> 00:08:02,760 Speaker 1: fifteen hundred scientists from Germany to the United States. Von 129 00:08:02,840 --> 00:08:06,240 Speaker 1: Braun would continue developing rockets in the US under various 130 00:08:06,280 --> 00:08:10,840 Speaker 1: military projects and research facilities, still with the dream of 131 00:08:10,880 --> 00:08:14,360 Speaker 1: achieving space flight. Now to say that he's a controversial 132 00:08:14,600 --> 00:08:18,840 Speaker 1: historical figure is really putting it mildly, but he's definitely 133 00:08:19,200 --> 00:08:22,120 Speaker 1: an inspiration for science fiction authors who like to create 134 00:08:22,400 --> 00:08:26,880 Speaker 1: sort of those amoral scientists who pursue their obsession with 135 00:08:27,000 --> 00:08:30,040 Speaker 1: no regard for the consequences, you know, following in that 136 00:08:30,120 --> 00:08:33,640 Speaker 1: old Jurassic Park line of you spent so much time 137 00:08:33,640 --> 00:08:36,800 Speaker 1: thinking if you could, you never thought if you should. 138 00:08:36,840 --> 00:08:41,079 Speaker 1: That kind of thing. Anyway, German and American scientists would 139 00:08:41,080 --> 00:08:45,000 Speaker 1: work together in numerous laboratories run by several universities as 140 00:08:45,000 --> 00:08:48,240 Speaker 1: well as the military branches, and they created rockets that 141 00:08:48,360 --> 00:08:52,200 Speaker 1: carried payloads holding scientific equipment designed to measure phenomena in 142 00:08:52,240 --> 00:08:55,760 Speaker 1: the upper atmosphere. So these were rockets that wouldn't escape 143 00:08:56,080 --> 00:08:59,880 Speaker 1: into orbit, but they would go very, very very high up. 144 00:09:00,360 --> 00:09:04,040 Speaker 1: As early as nineteen forty six, these different facilities were 145 00:09:04,040 --> 00:09:07,160 Speaker 1: looking at the possibility of launching a satellite into orbit, 146 00:09:07,520 --> 00:09:11,439 Speaker 1: but they largely concluded that these technologies weren't sophisticated enough 147 00:09:11,480 --> 00:09:14,400 Speaker 1: to make that a reality just yet. It was, however, 148 00:09:14,440 --> 00:09:17,120 Speaker 1: a long term goal. Now this brings us up to 149 00:09:17,160 --> 00:09:20,280 Speaker 1: the nineteen fifties. That's when the United States and the 150 00:09:20,280 --> 00:09:23,640 Speaker 1: then Soviet Union were deep in the Cold War. The 151 00:09:23,679 --> 00:09:27,079 Speaker 1: two nations had become more antagonistic to one another since 152 00:09:27,120 --> 00:09:30,040 Speaker 1: the end of World War Two, and each nation was 153 00:09:30,080 --> 00:09:33,240 Speaker 1: attempting to keep the other in check while expanding its 154 00:09:33,240 --> 00:09:37,160 Speaker 1: own power. They were also both racing to develop technologies 155 00:09:37,160 --> 00:09:41,120 Speaker 1: that can demonstrate superiority over the other. This is part 156 00:09:41,200 --> 00:09:44,199 Speaker 1: of what fueled the space race. Now, I don't want 157 00:09:44,200 --> 00:09:49,360 Speaker 1: to take anything away from the thousands of scientists, engineers, pilots, 158 00:09:49,400 --> 00:09:51,920 Speaker 1: and everyone else who worked on those early days in 159 00:09:51,960 --> 00:09:55,199 Speaker 1: the space industry. Though at this point it wasn't yet 160 00:09:55,440 --> 00:09:59,560 Speaker 1: an industry, there were lots of people who genuinely wanted 161 00:09:59,600 --> 00:10:03,400 Speaker 1: to use technology to explore beyond what humans had previously 162 00:10:03,440 --> 00:10:07,400 Speaker 1: been capable of and to push back our boundaries of ignorance. 163 00:10:07,640 --> 00:10:09,800 Speaker 1: There were a lot of brilliant people who worked on 164 00:10:09,840 --> 00:10:13,680 Speaker 1: projects with the motivation to further our scientific knowledge. But 165 00:10:13,840 --> 00:10:16,720 Speaker 1: the reason they really got the chance to do this 166 00:10:16,920 --> 00:10:19,480 Speaker 1: was because governments were willing to pour a lot of 167 00:10:19,559 --> 00:10:22,800 Speaker 1: resources into the endeavor in an effort to try and 168 00:10:22,880 --> 00:10:27,120 Speaker 1: get ahead of the opposition. So that's the backdrop, but 169 00:10:27,200 --> 00:10:30,679 Speaker 1: let's get to some details. In nineteen fifty two, the 170 00:10:30,720 --> 00:10:35,240 Speaker 1: International Council of Scientific Unions established that the period of 171 00:10:35,320 --> 00:10:39,439 Speaker 1: July one, nineteen fifty seven to December thirty one, nineteen 172 00:10:39,520 --> 00:10:44,479 Speaker 1: fifty eight, would be the international geophysical year to coincide 173 00:10:44,480 --> 00:10:48,320 Speaker 1: with a cycle of increased solar activity. And in case 174 00:10:48,400 --> 00:10:51,320 Speaker 1: you didn't know, the Sun goes through these cycles in 175 00:10:51,360 --> 00:10:55,320 Speaker 1: which there's more solar events like solar flares that happen 176 00:10:55,440 --> 00:10:58,520 Speaker 1: in that cycle. Then that's followed by a period of 177 00:10:58,640 --> 00:11:02,640 Speaker 1: decreased solar act ativity, not no solar activity, but less 178 00:11:02,800 --> 00:11:06,040 Speaker 1: of it. And these are regular and predictable, though the 179 00:11:06,080 --> 00:11:11,440 Speaker 1: individual activities the individual flares are not as predictable. Then 180 00:11:11,640 --> 00:11:15,800 Speaker 1: in nineteen fifty four, this same council said, Hey, you 181 00:11:15,880 --> 00:11:18,280 Speaker 1: know what would be really needo if we figured out 182 00:11:18,280 --> 00:11:21,559 Speaker 1: how to launch a scientific device up so that could 183 00:11:21,720 --> 00:11:25,559 Speaker 1: enter Earth's orbit. Such a thing had never been done before, 184 00:11:25,840 --> 00:11:28,040 Speaker 1: and the proposed goal was a device that would be 185 00:11:28,040 --> 00:11:31,040 Speaker 1: capable of mapping the surface of the Earth, giving us 186 00:11:31,240 --> 00:11:34,520 Speaker 1: the most accurate vision of the Earth's surface to date. 187 00:11:35,080 --> 00:11:38,520 Speaker 1: Several organizations had been looking at the logistics of getting 188 00:11:38,559 --> 00:11:41,920 Speaker 1: a payload up into orbit, though not necessarily as part 189 00:11:41,920 --> 00:11:45,559 Speaker 1: of the Council's proposal. The dream back in nineteen six 190 00:11:45,679 --> 00:11:48,480 Speaker 1: had never really gone away. It just was on the 191 00:11:48,480 --> 00:11:52,120 Speaker 1: back burner because it wasn't really possible. And then something 192 00:11:52,160 --> 00:11:55,680 Speaker 1: happened to spur the American government to put more support 193 00:11:55,720 --> 00:12:00,000 Speaker 1: behind this endeavor. A nineteen fifty four broadcast on Moscow 194 00:12:00,000 --> 00:12:03,960 Speaker 1: our radio revealed that the Soviets were seriously gearing up 195 00:12:04,000 --> 00:12:06,679 Speaker 1: to push for space flight. Now, that bit of information 196 00:12:06,720 --> 00:12:10,640 Speaker 1: didn't reach the general American public, but you can bet 197 00:12:10,800 --> 00:12:13,480 Speaker 1: that the federal government was very much aware of it. 198 00:12:14,040 --> 00:12:17,960 Speaker 1: A year later, in nineteen fifty the US government announced 199 00:12:17,960 --> 00:12:20,480 Speaker 1: a plan to launch a satellite, and that timing is 200 00:12:20,600 --> 00:12:25,080 Speaker 1: definitely not a coincidence. The government began to request proposals 201 00:12:25,120 --> 00:12:29,720 Speaker 1: from various laboratories to assist in getting this done, essentially saying, 202 00:12:30,280 --> 00:12:32,320 Speaker 1: give us your plan so we can figure out where 203 00:12:32,320 --> 00:12:35,640 Speaker 1: we're going to put our money. The Naval Research Laboratory 204 00:12:35,720 --> 00:12:40,080 Speaker 1: responded to this request for proposals with a project called Vanguard, 205 00:12:40,440 --> 00:12:44,080 Speaker 1: while other groups had alternative proposals and lacking a real 206 00:12:44,200 --> 00:12:47,880 Speaker 1: sense of urgency, the White House kind of waffled on this. 207 00:12:47,960 --> 00:12:50,640 Speaker 1: They delayed on selecting an option. They were kind of 208 00:12:50,679 --> 00:12:54,440 Speaker 1: weighing all of the choices, and this was somewhat understandable 209 00:12:54,480 --> 00:12:59,360 Speaker 1: as any path was going to require millions of taxpayer dollars, 210 00:12:59,400 --> 00:13:02,080 Speaker 1: so if the project was a success, it would be 211 00:13:02,120 --> 00:13:05,160 Speaker 1: a high point in science history. But if it failed, 212 00:13:05,720 --> 00:13:09,160 Speaker 1: taxpayers would get mighty miffed at what had been seen 213 00:13:09,200 --> 00:13:12,520 Speaker 1: as a huge waste of money, Like you took millions 214 00:13:12,520 --> 00:13:14,600 Speaker 1: of our dollars and you put it towards something that 215 00:13:14,640 --> 00:13:18,240 Speaker 1: didn't even work. That would be disastrous. Ultimately, the White 216 00:13:18,240 --> 00:13:21,560 Speaker 1: House chose Project Vanguard, and the hope was to be 217 00:13:21,640 --> 00:13:24,920 Speaker 1: the first nation to launch a man made satellite into orbit. 218 00:13:25,800 --> 00:13:29,000 Speaker 1: But that's not how things turned out. While Project Vanguard 219 00:13:29,080 --> 00:13:33,120 Speaker 1: was underway, the Soviets had been busy, and on October fourth, 220 00:13:33,400 --> 00:13:38,439 Speaker 1: nineteen fifty seven, the USSR shocked the world by launching 221 00:13:38,480 --> 00:13:43,199 Speaker 1: a nearly four pound or eighty three point six kilogram 222 00:13:43,360 --> 00:13:48,400 Speaker 1: satellite into orbit. That satellite's name was Sputnik. It was 223 00:13:48,480 --> 00:13:51,480 Speaker 1: about the size of a beach ball, and it would 224 00:13:51,559 --> 00:13:53,880 Speaker 1: orbit the Earth every hour and a half or so, 225 00:13:54,440 --> 00:13:58,120 Speaker 1: and it also essentially went beep. It sent out a 226 00:13:58,240 --> 00:14:00,960 Speaker 1: radio ping signal that could be picked up by radio 227 00:14:01,120 --> 00:14:06,160 Speaker 1: stations as the satellite passed overhead. That included radio sets 228 00:14:06,160 --> 00:14:10,440 Speaker 1: that were operated by amateurs, so ham radio operators could 229 00:14:10,480 --> 00:14:14,800 Speaker 1: hear as the satellite passed over and this launch shocked 230 00:14:14,960 --> 00:14:18,160 Speaker 1: the American public. Americans were under the belief that the 231 00:14:18,200 --> 00:14:21,600 Speaker 1: Soviet Union was far behind the United States from a 232 00:14:21,640 --> 00:14:26,480 Speaker 1: scientific and technological standpoint. Spot Nik flew in the face 233 00:14:26,560 --> 00:14:29,960 Speaker 1: of that, and it also raised a terrifying possibility. If 234 00:14:30,000 --> 00:14:33,520 Speaker 1: the USSR could launch a payload into space, could it 235 00:14:33,640 --> 00:14:36,280 Speaker 1: also create a weapon that could be fired from across 236 00:14:36,360 --> 00:14:40,240 Speaker 1: the world and still hit the United States. Spot Nik 237 00:14:40,400 --> 00:14:44,520 Speaker 1: launch spurred the U s Government into emergency mode. Vanguard 238 00:14:44,600 --> 00:14:46,880 Speaker 1: was still on the books, but the White House would 239 00:14:46,920 --> 00:14:50,760 Speaker 1: turn to the Army Redstone Arsenal Team led by one 240 00:14:51,160 --> 00:14:54,600 Speaker 1: Werner von Braun for an alternative, and it would be 241 00:14:54,640 --> 00:14:57,960 Speaker 1: called the Explorer one, and it would become the first 242 00:14:58,000 --> 00:15:01,320 Speaker 1: satellite launched by the United Dates. We have a bit 243 00:15:01,320 --> 00:15:03,120 Speaker 1: more history to go through when we come back, but 244 00:15:03,200 --> 00:15:05,960 Speaker 1: after that we'll go into how we get these satellites 245 00:15:05,960 --> 00:15:09,200 Speaker 1: into orbit, and then how they communicate with each other 246 00:15:09,240 --> 00:15:11,680 Speaker 1: and with stations here on Earth. But first let's take 247 00:15:11,920 --> 00:15:22,640 Speaker 1: a quick break. The first Spotnik satellite orbited the Earth 248 00:15:22,800 --> 00:15:26,200 Speaker 1: in October nineteen fifty seven, and it was never intended 249 00:15:26,240 --> 00:15:30,400 Speaker 1: to be a permanent fixture. It's orbit gradually decayed until 250 00:15:30,520 --> 00:15:33,840 Speaker 1: in January nineteen fifty eight, it burned up while re 251 00:15:34,000 --> 00:15:37,240 Speaker 1: entering the Earth's atmosphere. The Soviets launched spot Nick two 252 00:15:37,360 --> 00:15:40,720 Speaker 1: in November of nineteen fifty seven, and that's all I'm 253 00:15:40,760 --> 00:15:43,520 Speaker 1: going to say about that story. I've covered it before, 254 00:15:43,680 --> 00:15:46,680 Speaker 1: and that story makes me super sad and I hate 255 00:15:46,720 --> 00:15:50,200 Speaker 1: to talk about it. So the United States would launch 256 00:15:50,320 --> 00:15:54,480 Speaker 1: Explorer one on January thirty one, nineteen fifty eight, So 257 00:15:54,600 --> 00:15:57,760 Speaker 1: several months after both spot Nik and spot Nick two, 258 00:15:58,280 --> 00:16:02,280 Speaker 1: it did more than beep. Explore one did not just beep. 259 00:16:02,360 --> 00:16:05,360 Speaker 1: It also didn't kill a dog, So that's two things 260 00:16:05,400 --> 00:16:08,160 Speaker 1: that made it more advanced than either of the Sputnik satellites. 261 00:16:08,800 --> 00:16:13,160 Speaker 1: It carried scientific equipment designed to detect cosmic rays, and 262 00:16:13,200 --> 00:16:16,320 Speaker 1: the fact that it sent data with lower cosmic raid 263 00:16:16,400 --> 00:16:20,520 Speaker 1: counts than was anticipated. Let a scientist named James Van 264 00:16:20,600 --> 00:16:23,920 Speaker 1: Allen to hypothesize about the existence of a belt of 265 00:16:24,080 --> 00:16:28,040 Speaker 1: charged particles that were trapped by Earth's magnetic field. A 266 00:16:28,120 --> 00:16:32,040 Speaker 1: second satellite confirmed this hypothesis a couple of months later, 267 00:16:32,120 --> 00:16:35,840 Speaker 1: and the scientific community would name the charged particles the 268 00:16:35,960 --> 00:16:40,320 Speaker 1: Van Allen Belts. It took Explore one just under one 269 00:16:40,800 --> 00:16:44,160 Speaker 1: fifteen minutes to complete an orbit around the Earth, so 270 00:16:44,320 --> 00:16:46,880 Speaker 1: it would go around the planet about twelve and a 271 00:16:46,960 --> 00:16:50,200 Speaker 1: half times per day. It stayed in orbit a little 272 00:16:50,200 --> 00:16:53,320 Speaker 1: longer than Sputnik did. While the Soviet satellite burned up 273 00:16:53,320 --> 00:16:56,000 Speaker 1: on reentry just a few months after being launched, the 274 00:16:56,080 --> 00:17:01,480 Speaker 1: Explorer one remained in orbit from ninety eight until eighteen seventy. 275 00:17:01,520 --> 00:17:06,879 Speaker 1: It completed fifty eight thousand trips around Earth. The era 276 00:17:07,040 --> 00:17:10,000 Speaker 1: of the satellite was just beginning. While a lot of 277 00:17:10,040 --> 00:17:15,000 Speaker 1: media attention would shift towards space flights with humans and spacecraft, 278 00:17:15,000 --> 00:17:18,280 Speaker 1: the scientific community around the world continued to develop new 279 00:17:18,359 --> 00:17:22,480 Speaker 1: satellites for all sorts of purposes, from scientific research to 280 00:17:22,720 --> 00:17:27,840 Speaker 1: military reconnaissance to eventually global communications. One other thing I 281 00:17:27,880 --> 00:17:30,840 Speaker 1: want to mention before getting into the communications tech is 282 00:17:30,880 --> 00:17:34,200 Speaker 1: how a science fiction author proposed a type of satellite 283 00:17:34,200 --> 00:17:38,000 Speaker 1: that would be capable of communicating with a ground station 284 00:17:38,680 --> 00:17:41,119 Speaker 1: every hour of the day. See, if you have a 285 00:17:41,119 --> 00:17:44,240 Speaker 1: satellite in orbit like Explorer one, there's going to be 286 00:17:44,320 --> 00:17:47,639 Speaker 1: times when that satellite cannot send communications back to a 287 00:17:47,720 --> 00:17:51,560 Speaker 1: specific ground station because it's going to be out of sight. 288 00:17:52,080 --> 00:17:56,320 Speaker 1: Once the satellite passes a certain point overhead, communications will 289 00:17:56,359 --> 00:17:59,719 Speaker 1: start to drop. Placing ground stations around the world can 290 00:17:59,760 --> 00:18:02,159 Speaker 1: saw of that problem, but that gets into the issue 291 00:18:02,160 --> 00:18:06,720 Speaker 1: of establishing listening stations in places that you know aren't yours, 292 00:18:07,000 --> 00:18:11,040 Speaker 1: and that gets tricky from a political and real estate standpoint. 293 00:18:11,200 --> 00:18:13,640 Speaker 1: But obviously, if a satellite is on the opposite side 294 00:18:13,640 --> 00:18:16,880 Speaker 1: of the Earth from a listening station, the radio signals 295 00:18:16,960 --> 00:18:19,920 Speaker 1: can't get to the listening station, so you really only 296 00:18:19,960 --> 00:18:24,119 Speaker 1: have a window where you can have useful communications with 297 00:18:24,200 --> 00:18:28,800 Speaker 1: that particular type of satellite. For an effective communication satellite, 298 00:18:28,840 --> 00:18:31,679 Speaker 1: you need something in orbit that will remain over the 299 00:18:31,760 --> 00:18:36,040 Speaker 1: same fixed point here on Earth or in a pattern 300 00:18:36,119 --> 00:18:39,119 Speaker 1: that keeps it over the same general area of the Earth. 301 00:18:39,480 --> 00:18:42,240 Speaker 1: The satellite would need to travel around an orbital path 302 00:18:42,480 --> 00:18:45,240 Speaker 1: that keeps pace with the rotation of the Earth itself, 303 00:18:45,560 --> 00:18:49,880 Speaker 1: and this is called a geosynchronous orbit. The satellite will 304 00:18:49,880 --> 00:18:52,320 Speaker 1: travel over the same general region of the Earth because 305 00:18:52,359 --> 00:18:55,040 Speaker 1: it will orbit at the rate of once per day, 306 00:18:55,640 --> 00:18:59,520 Speaker 1: the same as the Earth's rotation. Now, science fiction author 307 00:18:59,640 --> 00:19:02,919 Speaker 1: Arthur See Clark, known for writing stuff like two thousand 308 00:19:03,000 --> 00:19:06,439 Speaker 1: one a Space Odyssey, made a sort of observation and 309 00:19:06,480 --> 00:19:10,720 Speaker 1: prediction back in nine It was published in a magazine 310 00:19:10,760 --> 00:19:14,080 Speaker 1: called Wireless World, and it proposed the idea of a 311 00:19:14,160 --> 00:19:19,040 Speaker 1: geo stationary satellite. Clark stated that a satellite at sufficient altitude, 312 00:19:19,400 --> 00:19:22,879 Speaker 1: and he was talking about a an altitude of forty 313 00:19:22,880 --> 00:19:26,480 Speaker 1: two thousand, one sixty four kilometers or around thirty five thousand, 314 00:19:26,560 --> 00:19:31,320 Speaker 1: seven eighty seven miles above the Earth's surface and placed 315 00:19:31,359 --> 00:19:34,879 Speaker 1: over the equator would have an orbital period equal to 316 00:19:34,920 --> 00:19:38,359 Speaker 1: the Earth's rotation, and so would remain above the same 317 00:19:38,440 --> 00:19:43,359 Speaker 1: fixed point on the equator. Now, forty two thousand, sixty 318 00:19:43,400 --> 00:19:48,720 Speaker 1: four kilometers altitude is obviously a lot, but without any context, 319 00:19:48,840 --> 00:19:52,160 Speaker 1: it's hard to say that's not so bad or wow, 320 00:19:52,400 --> 00:19:55,440 Speaker 1: that's way the heck out there. So just for comparison's sake, 321 00:19:55,720 --> 00:19:58,760 Speaker 1: it's good to remember that the International Space Station, which 322 00:19:58,960 --> 00:20:01,960 Speaker 1: isn't in geo sin grannous orbit, is a mirror four 323 00:20:02,080 --> 00:20:07,719 Speaker 1: hundred kilometers in altitude typically four hundred versus forty two thousand, 324 00:20:07,880 --> 00:20:12,720 Speaker 1: one d sixty four. Wow. Still as far out as 325 00:20:12,840 --> 00:20:17,880 Speaker 1: geosynchronous orbital areas are. That's not even halfway to the Moon. 326 00:20:18,000 --> 00:20:21,920 Speaker 1: The Moon is three four thousand, four hundred kilometers from Earth, 327 00:20:22,600 --> 00:20:27,399 Speaker 1: So a geostationary orbit is a specific subset of orbits 328 00:20:27,480 --> 00:20:31,440 Speaker 1: that fall into the geosynchronous orbit category. A satellite in 329 00:20:31,520 --> 00:20:35,280 Speaker 1: geosynchronous orbit will remain over a general region of Earth, 330 00:20:35,440 --> 00:20:39,399 Speaker 1: but if the satellite isn't directly above the equator, that 331 00:20:39,600 --> 00:20:42,720 Speaker 1: region varies a bit due to the Earth's tilt. In fact, 332 00:20:43,400 --> 00:20:45,920 Speaker 1: from the Earth's standpoint, it looks like the satellite is 333 00:20:45,960 --> 00:20:50,160 Speaker 1: moving in a figure eight pattern across the Earth's surface. 334 00:20:50,560 --> 00:20:53,680 Speaker 1: That's because the path of the satellite crosses above and 335 00:20:53,800 --> 00:20:57,240 Speaker 1: below the equator during the orbit and the Earth's rotation 336 00:20:57,359 --> 00:21:00,159 Speaker 1: throughout the day. A geo stationary orbit has to be 337 00:21:00,359 --> 00:21:03,360 Speaker 1: above the equator, and a satellite along that orbital path 338 00:21:03,640 --> 00:21:07,960 Speaker 1: will remain over its fixed point on Earth. Uh with 339 00:21:08,200 --> 00:21:11,360 Speaker 1: some caveats that I'll get to. Such a satellite could 340 00:21:11,400 --> 00:21:15,360 Speaker 1: remain in constant contact with the exact same ground stations, 341 00:21:15,680 --> 00:21:18,360 Speaker 1: and those ground stations would never need to move their 342 00:21:18,400 --> 00:21:21,800 Speaker 1: antenna to maintain contact, right they would just point their 343 00:21:21,840 --> 00:21:24,480 Speaker 1: antenna where the satellite is, and that's where the satellite 344 00:21:24,520 --> 00:21:27,880 Speaker 1: is going to stay. So it really makes it simplified 345 00:21:28,000 --> 00:21:31,800 Speaker 1: to communicate with that particular satellite. A network of those 346 00:21:31,840 --> 00:21:34,840 Speaker 1: types of satellites could communicate with one another as well 347 00:21:34,920 --> 00:21:37,320 Speaker 1: as their respective ground stations, and boom, you've got your 348 00:21:37,359 --> 00:21:41,840 Speaker 1: framework for a global communications infrastructure using radio signals beamed 349 00:21:41,880 --> 00:21:45,119 Speaker 1: out into space and then beamed back down to the Earth. Now, 350 00:21:45,240 --> 00:21:48,440 Speaker 1: Clark's idea was sound, but there wasn't really any practical 351 00:21:48,520 --> 00:21:52,520 Speaker 1: way to achieve it. Back in it would take twenty 352 00:21:52,640 --> 00:21:55,359 Speaker 1: years before the world would see the first commercial geo 353 00:21:55,480 --> 00:21:59,800 Speaker 1: stationary communications satellite, and that was called the Intel SAT one. 354 00:22:00,440 --> 00:22:02,640 Speaker 1: I think it would be handy for us to look 355 00:22:02,680 --> 00:22:06,560 Speaker 1: at what makes putting satellites into geo stationary orbits so tricky, 356 00:22:06,880 --> 00:22:09,280 Speaker 1: because it gives us an appreciation for the amount of 357 00:22:09,400 --> 00:22:13,320 Speaker 1: science and technology required to make stuff like communication networks 358 00:22:13,680 --> 00:22:19,200 Speaker 1: actually work. So let's start with just putting something into orbit. First, 359 00:22:19,400 --> 00:22:22,199 Speaker 1: you gotta put your satellite on a launch vehicle. Now, 360 00:22:22,359 --> 00:22:24,960 Speaker 1: essentially what we're talking about is a rocket. Now, back 361 00:22:25,000 --> 00:22:27,560 Speaker 1: in the old days, it was the Space Shuttle. We 362 00:22:27,680 --> 00:22:30,160 Speaker 1: often use the Space Shuttle to put satellites up into orbit, 363 00:22:30,280 --> 00:22:32,960 Speaker 1: and the Space Shuttle had rocket boosters attached to it 364 00:22:33,040 --> 00:22:36,200 Speaker 1: as well as its own rocket engine. But these days 365 00:22:36,240 --> 00:22:38,520 Speaker 1: we don't have a space Shuttle. We're talking about a 366 00:22:38,600 --> 00:22:42,359 Speaker 1: rocket here. Usually from our perspective, we launch those rockets 367 00:22:42,640 --> 00:22:45,680 Speaker 1: straight up from the Earth's surface. And there's a good 368 00:22:45,760 --> 00:22:48,720 Speaker 1: reason for this when you think about it. If you're 369 00:22:48,760 --> 00:22:52,840 Speaker 1: looking anywhere from above the horizon in one direction across 370 00:22:52,920 --> 00:22:55,760 Speaker 1: the entire arc of the sky to the horizon, and 371 00:22:55,840 --> 00:22:58,520 Speaker 1: the other direction. So let's say you're doing it from 372 00:22:58,560 --> 00:23:00,720 Speaker 1: east to west. Well, the whole time you do that, 373 00:23:00,880 --> 00:23:04,000 Speaker 1: you're technically looking out towards space. So why would you 374 00:23:04,080 --> 00:23:08,320 Speaker 1: launch straight up if every direction in that arc is 375 00:23:08,560 --> 00:23:11,760 Speaker 1: out towards space. What's because the shortest distance between two 376 00:23:11,800 --> 00:23:15,400 Speaker 1: points is a straight line, and launching straight up means 377 00:23:15,440 --> 00:23:18,960 Speaker 1: you're taking the shortest path to push through the thickest 378 00:23:19,000 --> 00:23:21,800 Speaker 1: part of the atmosphere. You're doing it in the most 379 00:23:21,880 --> 00:23:25,480 Speaker 1: efficient way, and that's really important because that means you're 380 00:23:25,480 --> 00:23:29,560 Speaker 1: consuming less fuel. Since fuel is one of the expensive 381 00:23:29,640 --> 00:23:33,800 Speaker 1: factors in space launches, and since adding more fuel adds 382 00:23:33,920 --> 00:23:36,520 Speaker 1: more weight to your launch vehicle, which means you then 383 00:23:36,600 --> 00:23:40,560 Speaker 1: have to factor that weight into your calculations, being frugal 384 00:23:41,040 --> 00:23:44,879 Speaker 1: with stuff is generally a really good idea. Once the 385 00:23:45,000 --> 00:23:48,960 Speaker 1: rocket reaches a certain altitude, the flight plan will call 386 00:23:49,280 --> 00:23:52,000 Speaker 1: for the rocket to adjust its direction so that the 387 00:23:52,040 --> 00:23:55,520 Speaker 1: payload our satellite in other words, gets to where it's 388 00:23:55,520 --> 00:23:58,639 Speaker 1: supposed to be, and a system called the inertial guidance 389 00:23:58,800 --> 00:24:01,840 Speaker 1: system will calculate the specific adjustments needed to put the 390 00:24:01,920 --> 00:24:06,600 Speaker 1: rocket on the correct path. That system uses accelerometers to 391 00:24:06,920 --> 00:24:10,400 Speaker 1: measure the various stresses it's experiencing in order to interpret 392 00:24:10,520 --> 00:24:14,359 Speaker 1: that as how the rocket is oriented with respect to 393 00:24:14,400 --> 00:24:17,719 Speaker 1: the Earth and what altitude it's at. Those accelerometers are 394 00:24:17,800 --> 00:24:20,439 Speaker 1: in gimbals so that they remain in the same orientation 395 00:24:20,520 --> 00:24:23,600 Speaker 1: with respect to the Earth. Typically, the rocket will head 396 00:24:23,880 --> 00:24:27,959 Speaker 1: toward the east once it reaches that altitude. So why 397 00:24:28,040 --> 00:24:30,320 Speaker 1: does it go toward the east was because the Earth 398 00:24:30,440 --> 00:24:33,159 Speaker 1: rotates to the east, and by going in that direction, 399 00:24:33,240 --> 00:24:37,120 Speaker 1: the rocket gets a bit of a boost, and you'd 400 00:24:37,160 --> 00:24:39,639 Speaker 1: get the best boost in speed if you happen to 401 00:24:39,720 --> 00:24:43,280 Speaker 1: be traveling along the path of the equator and going east. 402 00:24:43,800 --> 00:24:47,920 Speaker 1: The circumference of the Earth is approximately forty thousand kilometers, 403 00:24:48,160 --> 00:24:51,639 Speaker 1: and we know the Earth rotates once every twenty four hours, 404 00:24:52,800 --> 00:24:55,600 Speaker 1: not exactly twenty four hours, but close enough, so that 405 00:24:55,760 --> 00:24:58,280 Speaker 1: means a point on the equator must travel at a 406 00:24:58,359 --> 00:25:02,800 Speaker 1: speed of one thousand, six hundred sixty nine kilometers per hour. 407 00:25:03,240 --> 00:25:06,200 Speaker 1: If you are further north or south of the equator 408 00:25:06,640 --> 00:25:09,480 Speaker 1: and you are traveling east, you don't get quite that 409 00:25:09,760 --> 00:25:13,440 Speaker 1: same speed boost. For example, at Cape Canaveral, which is 410 00:25:13,480 --> 00:25:16,480 Speaker 1: in Florida in the United States, you start off at 411 00:25:16,520 --> 00:25:19,720 Speaker 1: a latitude that is twenty eight degrees thirty six minutes 412 00:25:19,800 --> 00:25:23,440 Speaker 1: twenty nine point seven seconds north of the equator, and 413 00:25:23,680 --> 00:25:27,000 Speaker 1: at this latitude the rotational speed of the Earth is 414 00:25:27,119 --> 00:25:31,119 Speaker 1: one thousand, four hundred forty kilometers per hour, so a 415 00:25:31,240 --> 00:25:34,880 Speaker 1: little bit less than the equatorial speed of one thousand, 416 00:25:34,960 --> 00:25:38,760 Speaker 1: six hundred sixty nine kilometers per hour. It might not 417 00:25:39,080 --> 00:25:42,359 Speaker 1: seem like a huge difference, but again that speed boost 418 00:25:42,440 --> 00:25:46,000 Speaker 1: means that you consume less fuel, So a flight path 419 00:25:46,119 --> 00:25:48,840 Speaker 1: that moves closer to the equator also means you need 420 00:25:49,000 --> 00:25:51,800 Speaker 1: less juice to get to your final orbit, as long 421 00:25:51,880 --> 00:25:55,040 Speaker 1: as that orbit is also near the equator. To escape 422 00:25:55,080 --> 00:25:58,040 Speaker 1: Earth's gravity, a rocket would have to accelerate to at 423 00:25:58,119 --> 00:26:03,159 Speaker 1: least forty thousand, three hundred twenty kilometers per hour. That 424 00:26:03,440 --> 00:26:06,960 Speaker 1: is Earth's escape velocity. If you move slower than that, 425 00:26:07,800 --> 00:26:10,359 Speaker 1: gravity claims the rocket, it will go into an orbit, 426 00:26:10,480 --> 00:26:15,040 Speaker 1: it won't escape Earth's gravitational pull, and eventually it'll fall 427 00:26:15,160 --> 00:26:18,560 Speaker 1: back to Earth if it's uh. If it's inertia, isn't 428 00:26:19,000 --> 00:26:22,520 Speaker 1: enough to keep it in space. But to put a 429 00:26:22,560 --> 00:26:26,400 Speaker 1: satellite into orbit, you don't need escape velocity, right, You're 430 00:26:26,440 --> 00:26:30,159 Speaker 1: not trying to escape Earth's gravity because an orbit is 431 00:26:30,320 --> 00:26:34,040 Speaker 1: a kind of controlled fall. It depends upon a gravitational pull. 432 00:26:34,400 --> 00:26:37,600 Speaker 1: So instead you have to reach orbital velocity. That's that 433 00:26:37,760 --> 00:26:41,480 Speaker 1: balance between a satellite's inertia and moving in a generally 434 00:26:41,600 --> 00:26:45,520 Speaker 1: straight line and the force of gravity that's pulling it downward. 435 00:26:46,040 --> 00:26:50,400 Speaker 1: That speed is dependent upon altitude. The closer the satellite 436 00:26:50,520 --> 00:26:53,880 Speaker 1: is to Earth, the greater the orbital velocity is required 437 00:26:53,920 --> 00:26:57,080 Speaker 1: in order to balance out the force of gravity. If 438 00:26:57,119 --> 00:27:00,440 Speaker 1: the satellite we're at two kilometers over the Earth, it 439 00:27:00,480 --> 00:27:03,760 Speaker 1: would have to travel at twenty seven thousand, four hundred 440 00:27:03,840 --> 00:27:07,919 Speaker 1: kilometers per hour to maintain orbit and not come falling 441 00:27:08,000 --> 00:27:12,120 Speaker 1: back down. But in a geo stationary orbit much much 442 00:27:12,240 --> 00:27:15,320 Speaker 1: much further out from Earth, it can travel at a 443 00:27:15,359 --> 00:27:20,440 Speaker 1: comparatively sluggish eleven thousand, three hundred kilometers per hour to 444 00:27:20,560 --> 00:27:23,679 Speaker 1: keep pace. Now remember that's to stay in a fixed 445 00:27:23,760 --> 00:27:26,359 Speaker 1: position above a point on the Earth that's traveling at 446 00:27:26,760 --> 00:27:29,760 Speaker 1: one thousand, six hundred sixty nine kilometers per hour. So 447 00:27:29,840 --> 00:27:33,320 Speaker 1: the satellite has to cover more distance because it's further 448 00:27:33,440 --> 00:27:35,680 Speaker 1: out in the same amount of time as the fixed 449 00:27:35,680 --> 00:27:37,560 Speaker 1: point on Earth, which is why it has to travel 450 00:27:37,720 --> 00:27:42,240 Speaker 1: faster than that relative position. And this is also why 451 00:27:42,359 --> 00:27:44,680 Speaker 1: we need to remember that those satellites that are closer 452 00:27:44,800 --> 00:27:48,280 Speaker 1: to us, they're actually going around the Earth more than 453 00:27:48,440 --> 00:27:50,760 Speaker 1: once per day. They might not be a whole lot 454 00:27:50,840 --> 00:27:52,800 Speaker 1: more than once per day, depending on how far out 455 00:27:52,840 --> 00:27:56,360 Speaker 1: it is, but they are not maintaining a fixed position 456 00:27:56,640 --> 00:27:59,320 Speaker 1: above a point on the Earth, so they actually do 457 00:27:59,440 --> 00:28:05,520 Speaker 1: have to travel faster. Not around in altitude, the rocket 458 00:28:05,600 --> 00:28:10,680 Speaker 1: will fire smaller thrusters to change that rocket's altitude and orientation, 459 00:28:10,840 --> 00:28:14,080 Speaker 1: so it enters into a more horizontal position relative to 460 00:28:14,160 --> 00:28:18,200 Speaker 1: the Earth, and at that orientation, the rocket releases its payload. 461 00:28:18,320 --> 00:28:21,240 Speaker 1: The satellite will part ways with the rocket and the 462 00:28:21,359 --> 00:28:23,840 Speaker 1: rocket will then fire some other thrusters that will help 463 00:28:23,920 --> 00:28:27,879 Speaker 1: create separation between the rocket and the satellite. Okay, so 464 00:28:28,440 --> 00:28:31,040 Speaker 1: we've boosted a satellite with a rocket so that it 465 00:28:31,119 --> 00:28:34,960 Speaker 1: can move into its orbital path. Upon separation, the satellite 466 00:28:35,080 --> 00:28:38,160 Speaker 1: is at the parage. Now, this is the lowest point 467 00:28:38,480 --> 00:28:41,719 Speaker 1: of its orbit, the closest it will be to the Earth. Now, 468 00:28:41,800 --> 00:28:44,520 Speaker 1: the satellite may cross the equator a couple of times 469 00:28:44,600 --> 00:28:47,480 Speaker 1: and it will reach its apogee, or its highest point 470 00:28:48,400 --> 00:28:51,360 Speaker 1: at at this section. And you can think of this 471 00:28:51,680 --> 00:28:55,160 Speaker 1: orbit is looking like it's spiraling out from the Earth, 472 00:28:55,240 --> 00:28:58,520 Speaker 1: like it starts off close and then as the satellite 473 00:28:58,560 --> 00:29:01,600 Speaker 1: goes around the planet, it starts to get further away 474 00:29:01,760 --> 00:29:04,920 Speaker 1: before it starts to come back in. So when we 475 00:29:04,960 --> 00:29:07,680 Speaker 1: talk about lowest and highest points, there's really quite a range. 476 00:29:07,960 --> 00:29:12,040 Speaker 1: So for example, the g Sat fourteen communications satellite, which 477 00:29:12,080 --> 00:29:16,840 Speaker 1: had a geostationary orbit, had a parody of KOs that's 478 00:29:16,840 --> 00:29:20,040 Speaker 1: where it's separated from its launch vehicle and its APOGE 479 00:29:20,560 --> 00:29:24,720 Speaker 1: was thirty six thousand kilometers now an appo G. The 480 00:29:24,800 --> 00:29:28,360 Speaker 1: satellite will conduct a series of controlled burns with onboard 481 00:29:28,440 --> 00:29:32,240 Speaker 1: thrusters on the satellite itself. This helps reshape the orbit 482 00:29:32,400 --> 00:29:36,040 Speaker 1: from being an elliptical path where it's further out from 483 00:29:36,080 --> 00:29:38,080 Speaker 1: the Earth on one side and closer to the Earth 484 00:29:38,160 --> 00:29:41,000 Speaker 1: on the other side, into a more circular path where 485 00:29:41,080 --> 00:29:44,840 Speaker 1: the Earth is at the center. This typically takes a 486 00:29:45,000 --> 00:29:48,440 Speaker 1: few different controlled burns. You could technically do it in one, 487 00:29:49,120 --> 00:29:51,520 Speaker 1: but it would probably require a lot more fuel, so 488 00:29:51,960 --> 00:29:57,800 Speaker 1: it's more frequently done in short bursts to gently reshape 489 00:29:57,840 --> 00:30:01,480 Speaker 1: that orbit. Ultimately re each in orbit where the satellite 490 00:30:01,520 --> 00:30:05,760 Speaker 1: remains in a fixed position above a specific point somewhere 491 00:30:05,800 --> 00:30:09,960 Speaker 1: along the equator. However, the satellite won't stay there forever 492 00:30:10,080 --> 00:30:12,360 Speaker 1: if you just leave things the way they are, because 493 00:30:12,440 --> 00:30:15,320 Speaker 1: stuff like the Moon and even the Earth itself will 494 00:30:15,440 --> 00:30:20,200 Speaker 1: affect the satellite's path through gravitational pull. Earth's gravitational field 495 00:30:20,360 --> 00:30:23,920 Speaker 1: is not uniform and these forces will slowly but surely 496 00:30:24,040 --> 00:30:26,400 Speaker 1: pull the satellite out of position, so once in a 497 00:30:26,440 --> 00:30:29,040 Speaker 1: while the satellite has to use those thrusters to correct 498 00:30:29,120 --> 00:30:31,480 Speaker 1: for that. It's another reason why it's really important to 499 00:30:31,520 --> 00:30:35,960 Speaker 1: conserve fuel. It conserves the lifespan of that satellite. The 500 00:30:36,040 --> 00:30:39,920 Speaker 1: more fuel you use, the less time that satellite is 501 00:30:39,920 --> 00:30:42,240 Speaker 1: going to be able to maintain that position, and it 502 00:30:42,280 --> 00:30:46,320 Speaker 1: will ultimately have an orbital decay and eventually it will 503 00:30:46,400 --> 00:30:50,320 Speaker 1: fall back to the Earth and break apart upon re entry. Now, 504 00:30:50,360 --> 00:30:52,960 Speaker 1: when we come back, we'll talk about how these satellites 505 00:30:53,080 --> 00:31:04,040 Speaker 1: actually communicate. But first let's take another quick break. Okay, 506 00:31:04,120 --> 00:31:07,920 Speaker 1: we've covered the early history of satellites and the challenges 507 00:31:08,040 --> 00:31:11,320 Speaker 1: of getting one into geo stationary orbit. Let's tackle how 508 00:31:11,440 --> 00:31:15,480 Speaker 1: they communicate. Now. I mentioned that a geostationary satellite is 509 00:31:15,560 --> 00:31:19,040 Speaker 1: ideal for communications because it will always maintain its relative 510 00:31:19,080 --> 00:31:21,520 Speaker 1: position above the Earth. So once you know where the 511 00:31:21,560 --> 00:31:24,200 Speaker 1: satellite is, you point your antenna in that direction and 512 00:31:24,280 --> 00:31:27,320 Speaker 1: you can pick up signals from that satellite. So let's 513 00:31:27,320 --> 00:31:30,120 Speaker 1: say you are a satellite TV subscriber and the company 514 00:31:30,160 --> 00:31:33,800 Speaker 1: providing your signal beams information up to a communication satellite 515 00:31:33,840 --> 00:31:36,760 Speaker 1: that's up in orbit, which then can broadcast that same 516 00:31:36,840 --> 00:31:40,520 Speaker 1: signal back down toward a region on Earth. If your 517 00:31:40,520 --> 00:31:43,600 Speaker 1: satellite dish is pointed toward that satellite, you should be 518 00:31:43,680 --> 00:31:45,960 Speaker 1: able to pick up on that signal. But what do 519 00:31:46,080 --> 00:31:49,440 Speaker 1: I mean when I say signals. So we're talking about 520 00:31:49,480 --> 00:31:53,880 Speaker 1: the electro magnetic spectrum, and specifically we're talking about radio waves. 521 00:31:54,160 --> 00:31:58,240 Speaker 1: So remember that the electro magnetic spectrum is huge. On 522 00:31:58,400 --> 00:32:01,520 Speaker 1: one end, you have the long are electromagnetic waves that 523 00:32:01,600 --> 00:32:05,120 Speaker 1: carry less energy. We have radio waves in that section. 524 00:32:05,640 --> 00:32:08,560 Speaker 1: On the opposite side, you have very short waves that 525 00:32:08,680 --> 00:32:12,360 Speaker 1: carry more energy. Gamma rays are on that side. So 526 00:32:12,520 --> 00:32:16,000 Speaker 1: within this spectrum, if we go longest to shortest in 527 00:32:16,120 --> 00:32:20,200 Speaker 1: wavelength of the types of electromagnetic radiation we have discovered, 528 00:32:20,640 --> 00:32:23,520 Speaker 1: keeping in mind, there can be others out there on 529 00:32:23,720 --> 00:32:26,239 Speaker 1: either end of the spectrum, we just have no way 530 00:32:26,280 --> 00:32:30,160 Speaker 1: of really detecting them. We have radio waves on alongside, 531 00:32:30,400 --> 00:32:35,480 Speaker 1: than microwaves, then infrared radiation, than visible light, than ultra 532 00:32:35,600 --> 00:32:40,320 Speaker 1: violet radiation, then X rays, and finally gamma raise. All 533 00:32:40,400 --> 00:32:43,280 Speaker 1: of these forms of energy travel at the speed of light, 534 00:32:43,640 --> 00:32:46,520 Speaker 1: which makes sense right. I mean, light is one of 535 00:32:46,680 --> 00:32:51,560 Speaker 1: the forms of electromagnetic energy. But they all have different 536 00:32:51,800 --> 00:32:55,000 Speaker 1: frequencies and that can get a little confusing. And this 537 00:32:55,240 --> 00:32:58,080 Speaker 1: is where an audio podcast really hits the challenge. So 538 00:32:58,960 --> 00:33:01,280 Speaker 1: let's imagine first second, that you've got a sheet of 539 00:33:01,400 --> 00:33:03,760 Speaker 1: graph paper in front of you, and you draw a 540 00:33:03,920 --> 00:33:06,680 Speaker 1: center line in the middle of that sheet, so there's 541 00:33:06,720 --> 00:33:09,760 Speaker 1: a solid center line, and you start on the left 542 00:33:09,840 --> 00:33:12,000 Speaker 1: side of the sheet at that center line, and you 543 00:33:12,080 --> 00:33:15,440 Speaker 1: start drawing a curve that moves upward from the center 544 00:33:15,560 --> 00:33:19,080 Speaker 1: line and has a peak that's at five squares above 545 00:33:19,240 --> 00:33:22,200 Speaker 1: the center line. Then you curve it back down so 546 00:33:22,360 --> 00:33:25,880 Speaker 1: it crosses that center line. You keep going past it, 547 00:33:26,320 --> 00:33:29,800 Speaker 1: and you draw essentially the mirror image of that curve, 548 00:33:29,920 --> 00:33:32,760 Speaker 1: but you're going down now to you hit five squares 549 00:33:32,880 --> 00:33:36,480 Speaker 1: below center. Then you slowly go back up to the 550 00:33:36,600 --> 00:33:40,560 Speaker 1: center again. That's sort of a representation of a sign wave. 551 00:33:40,800 --> 00:33:46,160 Speaker 1: You've drawn one full wavelength. So electromagnetic energy travels in 552 00:33:46,280 --> 00:33:50,560 Speaker 1: waves like this, but radio waves have much longer wavelengths 553 00:33:50,640 --> 00:33:53,840 Speaker 1: than gamma waves. That's, by the way, a heck of 554 00:33:53,920 --> 00:33:57,680 Speaker 1: an understatement. Radio waves carry less energy than gamma rays 555 00:33:57,720 --> 00:33:59,520 Speaker 1: as well, But there are a couple of reasons that 556 00:33:59,600 --> 00:34:03,880 Speaker 1: we you radio waves for communication. One is that they 557 00:34:04,000 --> 00:34:07,200 Speaker 1: require way less energy to generate than stuff like light. 558 00:34:08,000 --> 00:34:11,800 Speaker 1: But another very practical reason is that light waves and 559 00:34:11,920 --> 00:34:16,359 Speaker 1: shorter wavelengths of electromagnetic radiation get absorbed and scattered by 560 00:34:16,400 --> 00:34:20,560 Speaker 1: the Earth's atmosphere. In fact, gamma rays can even penetrate 561 00:34:20,640 --> 00:34:23,600 Speaker 1: the air, which is really good news for us, because 562 00:34:23,640 --> 00:34:26,080 Speaker 1: otherwise life as we know it would not have formed 563 00:34:26,160 --> 00:34:29,520 Speaker 1: on this planet. Gamma radiation would have wiped out anything 564 00:34:29,680 --> 00:34:34,120 Speaker 1: remotely resembling life as we know it. Radio waves, though 565 00:34:34,360 --> 00:34:38,000 Speaker 1: lower energy, can pass through the atmosphere without distortion, so 566 00:34:38,160 --> 00:34:42,160 Speaker 1: they are ideal for communication. And because the radio waves 567 00:34:42,200 --> 00:34:45,640 Speaker 1: are longer, fewer full wave lengths will pass a given 568 00:34:45,880 --> 00:34:49,680 Speaker 1: fixed point within a second than with gamma waves. Now, 569 00:34:49,760 --> 00:34:52,800 Speaker 1: I always use the analogy of a road to understand 570 00:34:52,880 --> 00:34:56,200 Speaker 1: this concept. So let's say you're standing by a road 571 00:34:56,680 --> 00:34:59,319 Speaker 1: and there's going to be a line of smart cars 572 00:34:59,400 --> 00:35:02,120 Speaker 1: that are travel bumper to bumper, and they're all going 573 00:35:02,200 --> 00:35:05,320 Speaker 1: to pass by you. The cars are all going fifty 574 00:35:05,400 --> 00:35:08,440 Speaker 1: kilometers per hour, and your job is to count the 575 00:35:08,560 --> 00:35:12,120 Speaker 1: number of smart cars that go past you in thirty seconds. 576 00:35:12,880 --> 00:35:15,080 Speaker 1: Then you've got to do the exact same thing, except 577 00:35:15,200 --> 00:35:18,880 Speaker 1: this time, instead of using smart cars, we're using double 578 00:35:19,000 --> 00:35:22,239 Speaker 1: length buses. Those double length busses are also going by 579 00:35:22,360 --> 00:35:26,560 Speaker 1: bumper to bumper. They're also traveling at fifty kilometers per hour. Now, 580 00:35:26,719 --> 00:35:29,480 Speaker 1: the smart cars and the buses are all traveling at 581 00:35:29,600 --> 00:35:32,360 Speaker 1: the same speed. Right, they're all traveling at fifty kilometers 582 00:35:32,400 --> 00:35:35,040 Speaker 1: per hour, but you're going to count way more smart 583 00:35:35,120 --> 00:35:38,040 Speaker 1: cars in those thirty seconds because they're shorter, more can 584 00:35:38,120 --> 00:35:41,359 Speaker 1: fit in that space within that time. Well, the same 585 00:35:41,440 --> 00:35:45,040 Speaker 1: thing is true with electromagnetic radiation. The speed limit is 586 00:35:45,160 --> 00:35:48,120 Speaker 1: set right the speed of light. It's the length of 587 00:35:48,200 --> 00:35:52,279 Speaker 1: the vehicles that changes. Now we measure of frequencies in 588 00:35:52,480 --> 00:35:56,040 Speaker 1: hurts h E R t Z. This refers to the 589 00:35:56,200 --> 00:35:59,919 Speaker 1: number of cycles or wavelengths that pass a fixed point 590 00:36:00,560 --> 00:36:04,320 Speaker 1: within a second. So one hurts would mean one wavelength 591 00:36:04,400 --> 00:36:08,279 Speaker 1: would pass in one second. The U. S. Navy initiated 592 00:36:08,320 --> 00:36:11,759 Speaker 1: a project that would transmit radio signals at frequencies as 593 00:36:11,840 --> 00:36:15,880 Speaker 1: low as thirty hurts, so that's thirty wavelengths in a second. Now, 594 00:36:16,000 --> 00:36:18,719 Speaker 1: keep in mind this is energy that's traveling at the 595 00:36:18,840 --> 00:36:23,000 Speaker 1: speed of light. The speed of light is two hundred thousand, 596 00:36:23,120 --> 00:36:27,959 Speaker 1: seven kilometers per second, so if we divide that number 597 00:36:28,000 --> 00:36:30,719 Speaker 1: by thirty cycles per second, we would see that the 598 00:36:30,840 --> 00:36:34,680 Speaker 1: wave length for thirty hurts is somewhere around nine thousand, 599 00:36:35,120 --> 00:36:40,520 Speaker 1: nine hundred nine three kilometers per cycle. So that means 600 00:36:40,760 --> 00:36:43,880 Speaker 1: a thirty hurts radio signal has a wavelength that is 601 00:36:44,040 --> 00:36:49,160 Speaker 1: nearly ten thousand kilometers long. Using that to communicate is 602 00:36:49,480 --> 00:36:53,840 Speaker 1: tricky because typically we need antenna to be some regular 603 00:36:54,000 --> 00:36:58,239 Speaker 1: fraction of the length of the wavelength that we're transmitting 604 00:36:58,280 --> 00:37:02,560 Speaker 1: and receiving, and a very common one is to have 605 00:37:02,800 --> 00:37:05,640 Speaker 1: an antenna that is one half or one quarter the 606 00:37:05,840 --> 00:37:09,279 Speaker 1: length of the wavelength of radio wave. But at ten 607 00:37:09,320 --> 00:37:13,399 Speaker 1: thousand kilometers, even half or one quarter is still way 608 00:37:13,480 --> 00:37:18,120 Speaker 1: too long, right, So practically we use much shorter wavelength 609 00:37:18,840 --> 00:37:22,680 Speaker 1: radio communications. Uh, it just doesn't make sense to build 610 00:37:22,719 --> 00:37:26,319 Speaker 1: antenna for the longer ones, and different countries chop up 611 00:37:26,360 --> 00:37:31,120 Speaker 1: the radio spectrum and designate bands of frequencies for specific uses. 612 00:37:31,360 --> 00:37:34,440 Speaker 1: For example, in the United States, AM radio uses a 613 00:37:34,520 --> 00:37:38,080 Speaker 1: frequency range between five dred twenty five killer hurts that 614 00:37:38,200 --> 00:37:42,200 Speaker 1: means five twenty five thousand cycles per second, so five 615 00:37:42,880 --> 00:37:45,520 Speaker 1: five thousand wavelengths will pass a fixed point in a 616 00:37:45,640 --> 00:37:48,840 Speaker 1: second at that frequency all the way up to one thousand, 617 00:37:48,920 --> 00:37:52,400 Speaker 1: seven hundred five killer hurts, which would be one million, 618 00:37:52,520 --> 00:37:56,719 Speaker 1: seven hundred five thousand cycles per second or one point 619 00:37:56,800 --> 00:37:58,680 Speaker 1: seven oh five mega hurts if you want to think 620 00:37:58,680 --> 00:38:01,719 Speaker 1: of it that way. And here we get too part 621 00:38:01,760 --> 00:38:05,040 Speaker 1: of that original question. The hurts here refers to the 622 00:38:05,239 --> 00:38:09,000 Speaker 1: radio frequency we're using as a carrier signal. It's all 623 00:38:09,040 --> 00:38:13,040 Speaker 1: about the frequency used to transmit and to receive information. 624 00:38:13,120 --> 00:38:16,400 Speaker 1: It has nothing to do with the amount of information 625 00:38:16,560 --> 00:38:20,640 Speaker 1: in that signal. It's specifically the frequency we're using to 626 00:38:20,920 --> 00:38:24,000 Speaker 1: transmit that signal. It's not directly related to the amount 627 00:38:24,040 --> 00:38:27,680 Speaker 1: of information being sent or processed. This is the medium 628 00:38:28,000 --> 00:38:30,080 Speaker 1: through which we're sending data. So you can think of 629 00:38:30,120 --> 00:38:33,120 Speaker 1: it as serving the exact same purpose as a physical 630 00:38:33,280 --> 00:38:36,879 Speaker 1: wire or cable, except instead of sending a signal down 631 00:38:36,960 --> 00:38:40,279 Speaker 1: a physical piece of hardware, we're sending it through the 632 00:38:40,440 --> 00:38:44,040 Speaker 1: air and through space as radio waves. Now, you could 633 00:38:44,120 --> 00:38:48,480 Speaker 1: try and communicate with a basic unaltered radio wave, but 634 00:38:48,760 --> 00:38:51,560 Speaker 1: you would really be limited by just doing pulses. Right, 635 00:38:51,680 --> 00:38:54,960 Speaker 1: the wave is either on or it's off, and this 636 00:38:55,040 --> 00:38:58,480 Speaker 1: would be kind of like sending Morse code. And maybe 637 00:38:58,760 --> 00:39:01,160 Speaker 1: do you leave it on for a short amount, like 638 00:39:01,239 --> 00:39:03,800 Speaker 1: a very short pulse as a dot, and maybe you 639 00:39:03,880 --> 00:39:05,680 Speaker 1: leave it on a little bit longer as a dash. 640 00:39:06,400 --> 00:39:09,239 Speaker 1: And when you don't have it on, there's a gap, right, 641 00:39:09,280 --> 00:39:12,920 Speaker 1: You know that that's a gap between individual pulses, But 642 00:39:13,080 --> 00:39:16,640 Speaker 1: that's not terribly useful. It's also really easy to have 643 00:39:16,920 --> 00:39:20,359 Speaker 1: errors introduced in that kind of signal, so we don't 644 00:39:20,440 --> 00:39:25,279 Speaker 1: typically use it that way. Instead, radio communications take a 645 00:39:25,480 --> 00:39:30,160 Speaker 1: basic frequency as a carrier signal, like I mentioned a 646 00:39:30,280 --> 00:39:33,359 Speaker 1: minute ago, and this is sort of the baseline. You've 647 00:39:33,360 --> 00:39:37,840 Speaker 1: got a basic signal at a specific frequency. By altering 648 00:39:37,920 --> 00:39:42,320 Speaker 1: that signal or modulating it, we can encode information with it, 649 00:39:42,800 --> 00:39:46,440 Speaker 1: and the deviations from the carrier signal all have meaning. 650 00:39:47,080 --> 00:39:50,440 Speaker 1: As long as we define what those deviations from the 651 00:39:50,520 --> 00:39:54,839 Speaker 1: carrier signal represent, we can encode and decode information sent 652 00:39:54,960 --> 00:39:58,719 Speaker 1: along that carrier wave. I mentioned a M radio a 653 00:39:58,760 --> 00:40:02,719 Speaker 1: couple of moments ago, and that stands for amplitude modulation. 654 00:40:03,200 --> 00:40:07,040 Speaker 1: Amplitude describes the measure of change in a single period 655 00:40:07,280 --> 00:40:11,359 Speaker 1: or cycle. But what does that actually mean in practical terms. Well, 656 00:40:11,440 --> 00:40:14,239 Speaker 1: in our drawing of a sign wave, when we drew 657 00:40:14,360 --> 00:40:18,160 Speaker 1: that that curve that went up and down, that amplitude 658 00:40:18,160 --> 00:40:21,160 Speaker 1: would describe how tall the peak and how deep the 659 00:40:21,280 --> 00:40:24,520 Speaker 1: trough is. And in our example we said it was 660 00:40:24,640 --> 00:40:28,640 Speaker 1: five squares, So that would be the amplitude of that 661 00:40:28,800 --> 00:40:31,880 Speaker 1: sign wave. If we were describing amplitude in terms of 662 00:40:32,000 --> 00:40:37,640 Speaker 1: squares with sound waves, amplitude corresponds with volume. The greater 663 00:40:37,800 --> 00:40:40,600 Speaker 1: the amplitude of a sound wave, the louder it is. 664 00:40:40,920 --> 00:40:44,360 Speaker 1: This does not affect the frequency, which with sound waves 665 00:40:44,440 --> 00:40:48,239 Speaker 1: we would experience as pitch. Right, a higher frequency would 666 00:40:48,239 --> 00:40:52,439 Speaker 1: be a higher pitch sound, So amplitude and pitch are 667 00:40:52,760 --> 00:40:56,840 Speaker 1: not connected. There are two different things. By making precise 668 00:40:57,120 --> 00:41:00,640 Speaker 1: changes in the amplitude of a radio wave as a 669 00:41:00,719 --> 00:41:04,080 Speaker 1: carrier wave, you can encode information on that radio wave. 670 00:41:04,360 --> 00:41:07,440 Speaker 1: A receiver tuned to the proper frequency will pick up 671 00:41:07,520 --> 00:41:11,520 Speaker 1: this incoming signal. It will detect those changes in amplitude 672 00:41:11,880 --> 00:41:15,480 Speaker 1: and it will decode that into useful information. So all 673 00:41:15,560 --> 00:41:17,800 Speaker 1: you really need to do to make this work is 674 00:41:17,880 --> 00:41:20,520 Speaker 1: to come up with a set of rules that corresponds 675 00:41:20,560 --> 00:41:22,640 Speaker 1: to the changes you're going to make in that signal. 676 00:41:23,040 --> 00:41:25,799 Speaker 1: If you say, if I change the amplitude in this way, 677 00:41:26,280 --> 00:41:29,359 Speaker 1: it means X, and if I change it in that way, 678 00:41:29,800 --> 00:41:32,480 Speaker 1: it means why. And then you have a decoder that 679 00:41:32,560 --> 00:41:35,719 Speaker 1: follows those same rules, but just reverses the process. You 680 00:41:35,800 --> 00:41:40,080 Speaker 1: can encode and decode information. It's a really elegant way 681 00:41:40,320 --> 00:41:43,919 Speaker 1: of being able to send data. But what about FM 682 00:41:44,040 --> 00:41:47,440 Speaker 1: radio Then, well, that that still involves modulation. But now 683 00:41:47,480 --> 00:41:51,480 Speaker 1: we're talking about frequency modulation. So you take that carrier 684 00:41:51,600 --> 00:41:55,200 Speaker 1: signal of a very specific radio frequency, and then you 685 00:41:55,280 --> 00:41:58,879 Speaker 1: make small changes to that frequency, not not big ones, 686 00:41:59,000 --> 00:42:02,920 Speaker 1: just small one. You're actually changing the wavelength of the 687 00:42:03,080 --> 00:42:06,880 Speaker 1: wave that you're sending out, making it slightly shorter or 688 00:42:06,960 --> 00:42:11,320 Speaker 1: slightly longer, and you can encode information onto the carrier 689 00:42:11,400 --> 00:42:14,920 Speaker 1: signal in a way similar to you could with amplitude modulation. 690 00:42:15,400 --> 00:42:18,480 Speaker 1: Now you can't change the wavelength too much or else 691 00:42:18,520 --> 00:42:21,200 Speaker 1: you'll push the signal outside of the effectiveness of your 692 00:42:21,239 --> 00:42:24,239 Speaker 1: transmitting and receiving antenna. But you actually have a good 693 00:42:24,320 --> 00:42:29,000 Speaker 1: deal of leeway there. With communication satellites, the modulation is 694 00:42:29,080 --> 00:42:33,799 Speaker 1: a little more complicated than changing amplitude or frequency. Satellites 695 00:42:33,920 --> 00:42:37,560 Speaker 1: use what is called phase modulation. So for this, let's 696 00:42:37,600 --> 00:42:40,920 Speaker 1: imagine you've got two radio waves, and let's say that 697 00:42:41,040 --> 00:42:44,759 Speaker 1: they are absolutely identical radio waves. They both have the 698 00:42:44,840 --> 00:42:48,160 Speaker 1: same frequency, and they have it where the crest of 699 00:42:48,280 --> 00:42:50,839 Speaker 1: one wave is lined up with the crest of another wave. 700 00:42:50,920 --> 00:42:54,360 Speaker 1: So wave one's crest and wave two's crest are perfectly 701 00:42:54,520 --> 00:42:57,600 Speaker 1: in alignment, and because they're the same frequency, they match 702 00:42:57,680 --> 00:42:59,759 Speaker 1: up all the way down the line. So they're in 703 00:43:00,000 --> 00:43:02,440 Speaker 1: box step with each other, or they're in phase with 704 00:43:02,600 --> 00:43:06,399 Speaker 1: one another. However, if you offset those two waves even 705 00:43:06,520 --> 00:43:09,120 Speaker 1: just a little bit, they are out of phase with 706 00:43:09,239 --> 00:43:12,840 Speaker 1: each other, and we can measure that bit by degrees, 707 00:43:13,680 --> 00:43:15,520 Speaker 1: if it's a lot or a little. If you have 708 00:43:15,640 --> 00:43:18,440 Speaker 1: two waves that are one degrees out of phase with 709 00:43:18,520 --> 00:43:21,400 Speaker 1: each other, it would mean that the crest of wave 710 00:43:21,480 --> 00:43:24,000 Speaker 1: one would match up with the lowest point of the 711 00:43:24,160 --> 00:43:27,239 Speaker 1: trough of wave two. They would be as out of 712 00:43:27,360 --> 00:43:31,839 Speaker 1: phase as they possibly could be. So phase modulation first 713 00:43:32,000 --> 00:43:37,000 Speaker 1: establishes a baseline wavelength of the signal. Then you begin 714 00:43:37,080 --> 00:43:39,920 Speaker 1: to alter the phase of that signal by moving that 715 00:43:40,040 --> 00:43:42,960 Speaker 1: wave out of phase in predetermined ways to represent a 716 00:43:43,120 --> 00:43:46,239 Speaker 1: zero or a one communicating in binary data. And you 717 00:43:46,320 --> 00:43:50,239 Speaker 1: can do this at incredibly fast speeds. And this is 718 00:43:50,280 --> 00:43:53,279 Speaker 1: where we get to data throughput, which we measure in 719 00:43:53,440 --> 00:43:57,040 Speaker 1: bits per second. Remember a bit is a basic unit 720 00:43:57,320 --> 00:44:00,400 Speaker 1: of digital information. It's a zero or a one. A 721 00:44:00,560 --> 00:44:05,480 Speaker 1: high throughput satellite can communicate at really high data throughput rates. 722 00:44:05,520 --> 00:44:08,200 Speaker 1: We're talking about on the order of a hundred gigabits 723 00:44:08,280 --> 00:44:13,080 Speaker 1: per second or more, and a gigabit is one billion bits, 724 00:44:13,400 --> 00:44:18,160 Speaker 1: so one billion basic units of digital information every second. 725 00:44:18,520 --> 00:44:22,239 Speaker 1: One billion bits per second. That's a lot of information. 726 00:44:22,719 --> 00:44:26,560 Speaker 1: So now we see what the mega hurts versus megabits 727 00:44:26,719 --> 00:44:29,360 Speaker 1: thing really comes down to. Mega hurts refers to the 728 00:44:29,520 --> 00:44:32,640 Speaker 1: frequency of the radio wave signal that we're using as 729 00:44:32,719 --> 00:44:35,640 Speaker 1: a medium. It's really just telling us the type of 730 00:44:35,719 --> 00:44:38,480 Speaker 1: connection being used, the signal that's being sent out by 731 00:44:38,520 --> 00:44:41,239 Speaker 1: a transmitter and the signal that's being picked up by 732 00:44:41,280 --> 00:44:45,480 Speaker 1: a receiver. The receiver is ignoring all other signals except 733 00:44:45,520 --> 00:44:48,399 Speaker 1: for the one that it's tuned into. Otherwise you would 734 00:44:48,440 --> 00:44:50,880 Speaker 1: just be getting tons of noise and you wouldn't be 735 00:44:50,920 --> 00:44:53,239 Speaker 1: able to tell what was the signal you were looking 736 00:44:53,280 --> 00:44:56,600 Speaker 1: for versus everything else. There are a few other factors 737 00:44:56,719 --> 00:44:59,400 Speaker 1: that allow a receiver to lock into a specific transmission, 738 00:44:59,440 --> 00:45:02,800 Speaker 1: but that gets a lot more technical and uh, mega 739 00:45:02,880 --> 00:45:06,920 Speaker 1: hurts does not directly correlate to data throughput. Uh. The 740 00:45:07,040 --> 00:45:09,200 Speaker 1: frequency does have an effect, but I'll have to go 741 00:45:09,320 --> 00:45:12,040 Speaker 1: into more detail in the future episode because it requires 742 00:45:12,080 --> 00:45:18,040 Speaker 1: a more involved discussion about the nature of frequencies versus 743 00:45:18,160 --> 00:45:22,360 Speaker 1: data throughput. Megabits or gigabits or kill a bits or 744 00:45:22,400 --> 00:45:26,040 Speaker 1: whatever just tells us how much information can be transmitted 745 00:45:26,200 --> 00:45:30,040 Speaker 1: per unit of time per second, for example. Now, I 746 00:45:30,160 --> 00:45:33,000 Speaker 1: hope all of this gives you, guys a deeper understanding 747 00:45:33,040 --> 00:45:36,200 Speaker 1: of what's going on with satellites, including how amazing it 748 00:45:36,360 --> 00:45:38,640 Speaker 1: is the humans figured out how to get stuff out 749 00:45:38,719 --> 00:45:41,719 Speaker 1: into space in the first place, let alone use it 750 00:45:41,800 --> 00:45:46,680 Speaker 1: to communicate information back to Earth. It's a phenomenal achievement 751 00:45:46,960 --> 00:45:50,800 Speaker 1: and really a remarkable display of how a deep understanding 752 00:45:50,840 --> 00:45:53,520 Speaker 1: of science leads to us being able to leverage that 753 00:45:53,680 --> 00:45:57,399 Speaker 1: understanding through technology. It's also why I argue that exploratory 754 00:45:57,520 --> 00:46:00,879 Speaker 1: science is a great thing in gen a role where 755 00:46:01,000 --> 00:46:05,160 Speaker 1: you set out to understand more about the universe, not 756 00:46:05,440 --> 00:46:09,200 Speaker 1: for a specific application, but more just to get that understanding, 757 00:46:09,480 --> 00:46:13,839 Speaker 1: because you never know what kind of applications could come 758 00:46:13,960 --> 00:46:16,839 Speaker 1: from that as we learn more about how the universe works. 759 00:46:16,880 --> 00:46:20,080 Speaker 1: That's why I think funding for sciences is so important. 760 00:46:20,280 --> 00:46:22,520 Speaker 1: You never know what we'll learn and then how we'll 761 00:46:22,560 --> 00:46:25,800 Speaker 1: put that learning to use to benefit people in the future. 762 00:46:26,120 --> 00:46:29,239 Speaker 1: So um fund science, I guess, is what I'm saying. 763 00:46:29,719 --> 00:46:33,839 Speaker 1: All right, guys, that wraps up this discussion about communications satellites, 764 00:46:34,080 --> 00:46:38,040 Speaker 1: very very high overview pun intended of communication satellites. We 765 00:46:38,080 --> 00:46:39,759 Speaker 1: can get into a lot more detail if you guys 766 00:46:39,840 --> 00:46:43,000 Speaker 1: want to um, but it does get pretty tricky. Also, 767 00:46:43,040 --> 00:46:45,120 Speaker 1: it gets tricky for me because I have to get 768 00:46:45,160 --> 00:46:47,040 Speaker 1: a deeper understanding myself in order to be able to 769 00:46:47,080 --> 00:46:50,160 Speaker 1: communicate it properly. And also just figuring out how to 770 00:46:50,280 --> 00:46:53,319 Speaker 1: explain stuff without visual aids is always a challenge. If 771 00:46:53,360 --> 00:46:56,000 Speaker 1: you have any other suggestions, maybe there's some other topic 772 00:46:56,160 --> 00:46:58,960 Speaker 1: totally unrelated to satellite communications that you would like me 773 00:46:59,040 --> 00:47:01,360 Speaker 1: to talk about. Reach out to me on Twitter. The 774 00:47:01,440 --> 00:47:04,520 Speaker 1: handle is text stuff h s W and I'll talk 775 00:47:04,560 --> 00:47:12,440 Speaker 1: to you again really soon y. Text Stuff is an 776 00:47:12,480 --> 00:47:16,120 Speaker 1: I Heart Radio production. For more podcasts from my Heart Radio, 777 00:47:16,520 --> 00:47:19,640 Speaker 1: visit the i Heart Radio app, Apple Podcasts, or wherever 778 00:47:19,760 --> 00:47:21,280 Speaker 1: you listen to your favorite shows.