WEBVTT - TechStuff to Major Tom 0:00:04.400 --> 0:00:07.800 Welcome to Text Stuff, a production from my Heart Radio. 0:00:12.080 --> 0:00:15.240 Hey there, and welcome to tech Stuff. I'm your host, 0:00:15.480 --> 0:00:19.360 Jonathan Strickland. I'm an executive producer with I Heart Radio 0:00:19.480 --> 0:00:23.079 and I love all things tech and today's episode is 0:00:23.120 --> 0:00:27.440 in response to a request Carlos wrote to me and 0:00:27.520 --> 0:00:30.240 asked me this. He said, Hey, Jonathan, great work on 0:00:30.280 --> 0:00:33.760 your podcast. I am looking at satellite communications and I 0:00:33.880 --> 0:00:36.920 find it hard to understand how are they used for 0:00:37.000 --> 0:00:40.680 Internet access, why they use mega hurts instead of megabits 0:00:40.720 --> 0:00:43.400 per second, and in general, how they communicate to Earth 0:00:43.720 --> 0:00:47.879 perhaps a continuation episode. Well that's a great topic, and 0:00:47.920 --> 0:00:50.440 I get how it can be confusing when a technology 0:00:50.520 --> 0:00:54.880 uses different but similar sounding terms. So today we're going 0:00:54.920 --> 0:00:58.600 to break down satellite communications and how they work. Now, 0:00:59.080 --> 0:01:01.560 the simple and there to the question is that satellites 0:01:01.600 --> 0:01:05.200 communicate using radio waves, and in fact that's where the 0:01:05.200 --> 0:01:08.720 mega hurts stuff comes in. But that doesn't really create 0:01:08.800 --> 0:01:11.920 an understanding of what's going on. To do that, we 0:01:11.959 --> 0:01:14.520 need to jump into some history. And you might think 0:01:14.560 --> 0:01:17.400 I would start with nineteen fifty seven with the first 0:01:17.440 --> 0:01:21.199 satellite to achieve orbit, but you're wrong. We're going back 0:01:21.240 --> 0:01:24.839 a bit further I'm going to start all the way 0:01:24.880 --> 0:01:29.840 back in nineteen o three, which sounds crazy, right, but 0:01:30.440 --> 0:01:35.040 that's when a Russian scientist named Konstantine Selkovsky worked out 0:01:35.160 --> 0:01:38.200 the mass that suggested that, yeah, it would be possible 0:01:38.560 --> 0:01:41.520 to build a rocket that we could launch from Earth 0:01:41.800 --> 0:01:45.720 and lift a payload into space, so that that payload, 0:01:45.880 --> 0:01:50.040 that object would be in an orbit around Earth. Now, 0:01:50.080 --> 0:01:54.160 see gravity pulls downward, or if you prefer it, pulls 0:01:54.200 --> 0:01:57.560 towards a center of mass, because you know, once we 0:01:57.560 --> 0:02:00.960 get out into space, concepts like up and down don't 0:02:01.320 --> 0:02:05.840 have so much meaning. Inertia of a moving body tends 0:02:05.920 --> 0:02:08.280 to make it move in a in a straight line. 0:02:08.360 --> 0:02:11.440 So think of it as we have a perfectly leveled table. 0:02:11.639 --> 0:02:13.360 Now we've got a ball on the table, and you 0:02:13.440 --> 0:02:16.240 give a push on the ball, it will tend to 0:02:16.240 --> 0:02:18.840 travel in a straight line in the same direction as 0:02:18.919 --> 0:02:23.760 your push. So if there is a balance between gravity 0:02:23.880 --> 0:02:27.280 and inertia, an object will continue in a straight line 0:02:27.320 --> 0:02:31.040 while being pulled toward a center of mass. So, if 0:02:31.040 --> 0:02:33.320 the object is moving fast enough, the ground of the 0:02:33.360 --> 0:02:37.360 Earth will curve away from its path as it falls 0:02:37.400 --> 0:02:40.240 towards the Earth. So it's kind of in a constant 0:02:40.280 --> 0:02:43.320 state of falling. This, by the way, is one of 0:02:43.520 --> 0:02:46.880 many proofs that the Earth is round, because if it weren't, 0:02:47.320 --> 0:02:50.959 orbits would not work. But we know they work because 0:02:50.960 --> 0:02:54.000 we built stuff, we put it in orbit, We depend 0:02:54.040 --> 0:02:56.600 on that stuff on a day to day basis, So 0:02:56.919 --> 0:03:00.440 that alone is proof that the Earth is round. Now, 0:03:00.560 --> 0:03:05.000 Silkovski proved that an orbiting satellite was possible from a 0:03:05.080 --> 0:03:08.720 mathematical point of view, but there was no real, you know, 0:03:09.080 --> 0:03:12.600 rush to prove him right. For one thing, what the 0:03:12.639 --> 0:03:15.640 heck would the ding dang durn thing do once it 0:03:15.720 --> 0:03:19.160 was up there? I mean, would we just be throwing 0:03:19.240 --> 0:03:22.480 resources at something just to say we did it? I mean, 0:03:22.480 --> 0:03:24.919 this would be the equivalent of answering the question why 0:03:24.960 --> 0:03:28.560 do you want to climb Mount Everest with because it's there? 0:03:29.400 --> 0:03:32.520 That might not be the best answer for all situations. Besides, 0:03:32.680 --> 0:03:37.280 Silkowsky's work wasn't widely known for many years. In fact, 0:03:37.520 --> 0:03:42.040 two decades later, a Romanian scientist named herman O Birth 0:03:43.080 --> 0:03:48.040 essentially worked out the same stuff completely independently of Solkovsky's work. 0:03:48.040 --> 0:03:51.920 He wasn't aware of Silkovsky. But again, even ober It's 0:03:51.960 --> 0:03:56.600 work was confined to a relatively small circle of physicists, 0:03:56.720 --> 0:04:00.520 or as the British would say, Boffin's he. Even well 0:04:00.640 --> 0:04:04.160 read physicists in the United States had never heard of 0:04:04.200 --> 0:04:07.920 either of these two people, and while they were all 0:04:07.960 --> 0:04:12.880 thinking about space, none of them had actually proposed an 0:04:12.960 --> 0:04:18.040 artificial satellite as of yet. Robert Goddard, an American, made 0:04:18.040 --> 0:04:21.720 another important contribution to our space efforts. While pursuing post 0:04:21.800 --> 0:04:26.720 graduate studies at Princeton University. He demonstrated that rocket propulsion 0:04:26.760 --> 0:04:30.719 would work even in the airless environment of space, and 0:04:30.760 --> 0:04:34.640 this was around nineteen sixteen or so, and he built 0:04:34.680 --> 0:04:39.039 a solid fuel rocket in nineteen eighteen. But his funding 0:04:39.160 --> 0:04:41.960 dried up around the time that World War One ended, 0:04:42.080 --> 0:04:44.359 and this is going to be an ongoing theme in 0:04:44.360 --> 0:04:47.680 the space industry. Scientists seem to get way more funds 0:04:48.279 --> 0:04:52.160 when there are possible military applications to the technology they're developing, 0:04:52.360 --> 0:04:55.799 you know, beyond just putting stuff up into space. Goddard 0:04:55.800 --> 0:04:59.080 would continue his work through various colleges up until World 0:04:59.120 --> 0:05:01.640 War Two, when a again he would receive funding to 0:05:01.680 --> 0:05:04.840 work on rocketry with applications for the military, in this 0:05:04.920 --> 0:05:08.120 case largely in the world of jet assisted takeoff or 0:05:08.520 --> 0:05:14.080 j to j A. T O. Germany also famously pursued 0:05:14.160 --> 0:05:17.159 rocketry in World War Two, using it to great effect 0:05:17.240 --> 0:05:20.839 with devastating weapons like the V two rocket. One of 0:05:20.839 --> 0:05:24.880 the scientists chiefly responsible for that V two rocket was 0:05:24.960 --> 0:05:29.840 Werner von Braun, sort of Germany's equivalent of Goddard. Von 0:05:29.880 --> 0:05:34.039 Braun was interested in spaceflight, but like Goddard, he put 0:05:34.080 --> 0:05:36.560 his mind to work for a military in an effort 0:05:36.560 --> 0:05:41.159 to fund his research. Germany used von Braun's rockets to 0:05:41.440 --> 0:05:45.719 fire upon cities like London, killing thousands and devastating entire 0:05:45.800 --> 0:05:51.040 sections of the city. Von Braun wasn't necessarily the most 0:05:51.400 --> 0:05:55.000 ardent supporter of the Nazi regime during World War Two, 0:05:55.320 --> 0:05:57.880 but he joined the Nazi Party and became a member 0:05:57.880 --> 0:06:00.080 of the s S and while he didn't seem to 0:06:00.120 --> 0:06:03.440 share any real political views with the Nazis, he did 0:06:03.520 --> 0:06:06.320 see the allegiance to the party as a necessity for 0:06:06.400 --> 0:06:08.760 him to get the resources he wanted to pursue the 0:06:08.800 --> 0:06:13.120 goal of space flight, so to him, the ends justified 0:06:13.200 --> 0:06:17.480 the means. In nineteen forty three, scientists working for the U. S. 0:06:17.560 --> 0:06:20.440 Navy began to look into the possibility that the Nazis 0:06:20.480 --> 0:06:24.680 were developing rockets capable of putting an artificial satellite into orbit. 0:06:25.120 --> 0:06:27.680 Their worry was that a device like that might be 0:06:27.760 --> 0:06:31.800 used for reconnaissance or spy technology, or maybe even as 0:06:31.800 --> 0:06:35.920 a weapon, whether a weapon capable of actually creating physical 0:06:36.000 --> 0:06:39.960 destruction or a more psychological weapon to terrorize people into 0:06:40.000 --> 0:06:43.599 thinking they'd be subjected to death rays or something. The 0:06:43.680 --> 0:06:47.680 scientists concluded that it could be possible to launch a 0:06:47.720 --> 0:06:51.040 satellite into orbit. Essentially, they were retreading the ground that 0:06:51.120 --> 0:06:54.719 Siolkovsky and o Berth had already walked, and there was 0:06:54.760 --> 0:06:58.520 some early interest in exploring that as an actual option. 0:06:59.120 --> 0:07:02.839 In nineteen four be four, while at a party, Von 0:07:02.960 --> 0:07:06.599 Brown got inebriated and he let it slip that he 0:07:06.720 --> 0:07:09.880 thought the war wouldn't end well for Germany, which was 0:07:09.920 --> 0:07:13.320 pretty much a foregone conclusion, but it was essentially a 0:07:13.360 --> 0:07:16.760 treasonous act. To actually suggest that Germany would lose the 0:07:16.800 --> 0:07:21.200 war was an act of treason. So he was arrested. However, 0:07:21.240 --> 0:07:24.800 he was never incarcerated. It did send a message to him, 0:07:24.960 --> 0:07:28.200 you know, Von Brown said, Wow, my place here is 0:07:28.240 --> 0:07:30.200 not as secure as I would like it to be. 0:07:30.800 --> 0:07:34.880 So he and several other rockets scientists went into hiding. 0:07:35.280 --> 0:07:40.800 Upon hearing that Hitler had committed suicide, these scientists surrendered 0:07:40.800 --> 0:07:44.160 to American soldiers and they were part of a negotiation 0:07:44.560 --> 0:07:47.840 to come to America and essentially pursue the same sort 0:07:47.880 --> 0:07:50.640 of work they had been doing for Germany, but in 0:07:50.680 --> 0:07:54.520 the United States. Now. This was known in classified circles 0:07:54.600 --> 0:07:57.800 as Operation paper Clip, and it involved bringing more than 0:07:57.880 --> 0:08:02.760 fifteen hundred scientists from Germany to the United States. Von 0:08:02.840 --> 0:08:06.240 Braun would continue developing rockets in the US under various 0:08:06.280 --> 0:08:10.840 military projects and research facilities, still with the dream of 0:08:10.880 --> 0:08:14.360 achieving space flight. Now to say that he's a controversial 0:08:14.600 --> 0:08:18.840 historical figure is really putting it mildly, but he's definitely 0:08:19.200 --> 0:08:22.120 an inspiration for science fiction authors who like to create 0:08:22.400 --> 0:08:26.880 sort of those amoral scientists who pursue their obsession with 0:08:27.000 --> 0:08:30.040 no regard for the consequences, you know, following in that 0:08:30.120 --> 0:08:33.640 old Jurassic Park line of you spent so much time 0:08:33.640 --> 0:08:36.800 thinking if you could, you never thought if you should. 0:08:36.840 --> 0:08:41.079 That kind of thing. Anyway, German and American scientists would 0:08:41.080 --> 0:08:45.000 work together in numerous laboratories run by several universities as 0:08:45.000 --> 0:08:48.240 well as the military branches, and they created rockets that 0:08:48.360 --> 0:08:52.200 carried payloads holding scientific equipment designed to measure phenomena in 0:08:52.240 --> 0:08:55.760 the upper atmosphere. So these were rockets that wouldn't escape 0:08:56.080 --> 0:08:59.880 into orbit, but they would go very, very very high up. 0:09:00.360 --> 0:09:04.040 As early as nineteen forty six, these different facilities were 0:09:04.040 --> 0:09:07.160 looking at the possibility of launching a satellite into orbit, 0:09:07.520 --> 0:09:11.439 but they largely concluded that these technologies weren't sophisticated enough 0:09:11.480 --> 0:09:14.400 to make that a reality just yet. It was, however, 0:09:14.440 --> 0:09:17.120 a long term goal. Now this brings us up to 0:09:17.160 --> 0:09:20.280 the nineteen fifties. That's when the United States and the 0:09:20.280 --> 0:09:23.640 then Soviet Union were deep in the Cold War. The 0:09:23.679 --> 0:09:27.079 two nations had become more antagonistic to one another since 0:09:27.120 --> 0:09:30.040 the end of World War Two, and each nation was 0:09:30.080 --> 0:09:33.240 attempting to keep the other in check while expanding its 0:09:33.240 --> 0:09:37.160 own power. They were also both racing to develop technologies 0:09:37.160 --> 0:09:41.120 that can demonstrate superiority over the other. This is part 0:09:41.200 --> 0:09:44.199 of what fueled the space race. Now, I don't want 0:09:44.200 --> 0:09:49.360 to take anything away from the thousands of scientists, engineers, pilots, 0:09:49.400 --> 0:09:51.920 and everyone else who worked on those early days in 0:09:51.960 --> 0:09:55.199 the space industry. Though at this point it wasn't yet 0:09:55.440 --> 0:09:59.560 an industry, there were lots of people who genuinely wanted 0:09:59.600 --> 0:10:03.400 to use technology to explore beyond what humans had previously 0:10:03.440 --> 0:10:07.400 been capable of and to push back our boundaries of ignorance. 0:10:07.640 --> 0:10:09.800 There were a lot of brilliant people who worked on 0:10:09.840 --> 0:10:13.680 projects with the motivation to further our scientific knowledge. But 0:10:13.840 --> 0:10:16.720 the reason they really got the chance to do this 0:10:16.920 --> 0:10:19.480 was because governments were willing to pour a lot of 0:10:19.559 --> 0:10:22.800 resources into the endeavor in an effort to try and 0:10:22.880 --> 0:10:27.120 get ahead of the opposition. So that's the backdrop, but 0:10:27.200 --> 0:10:30.679 let's get to some details. In nineteen fifty two, the 0:10:30.720 --> 0:10:35.240 International Council of Scientific Unions established that the period of 0:10:35.320 --> 0:10:39.439 July one, nineteen fifty seven to December thirty one, nineteen 0:10:39.520 --> 0:10:44.479 fifty eight, would be the international geophysical year to coincide 0:10:44.480 --> 0:10:48.320 with a cycle of increased solar activity. And in case 0:10:48.400 --> 0:10:51.320 you didn't know, the Sun goes through these cycles in 0:10:51.360 --> 0:10:55.320 which there's more solar events like solar flares that happen 0:10:55.440 --> 0:10:58.520 in that cycle. Then that's followed by a period of 0:10:58.640 --> 0:11:02.640 decreased solar act ativity, not no solar activity, but less 0:11:02.800 --> 0:11:06.040 of it. And these are regular and predictable, though the 0:11:06.080 --> 0:11:11.440 individual activities the individual flares are not as predictable. Then 0:11:11.640 --> 0:11:15.800 in nineteen fifty four, this same council said, Hey, you 0:11:15.880 --> 0:11:18.280 know what would be really needo if we figured out 0:11:18.280 --> 0:11:21.559 how to launch a scientific device up so that could 0:11:21.720 --> 0:11:25.559 enter Earth's orbit. Such a thing had never been done before, 0:11:25.840 --> 0:11:28.040 and the proposed goal was a device that would be 0:11:28.040 --> 0:11:31.040 capable of mapping the surface of the Earth, giving us 0:11:31.240 --> 0:11:34.520 the most accurate vision of the Earth's surface to date. 0:11:35.080 --> 0:11:38.520 Several organizations had been looking at the logistics of getting 0:11:38.559 --> 0:11:41.920 a payload up into orbit, though not necessarily as part 0:11:41.920 --> 0:11:45.559 of the Council's proposal. The dream back in nineteen six 0:11:45.679 --> 0:11:48.480 had never really gone away. It just was on the 0:11:48.480 --> 0:11:52.120 back burner because it wasn't really possible. And then something 0:11:52.160 --> 0:11:55.680 happened to spur the American government to put more support 0:11:55.720 --> 0:12:00.000 behind this endeavor. A nineteen fifty four broadcast on Moscow 0:12:00.000 --> 0:12:03.960 our radio revealed that the Soviets were seriously gearing up 0:12:04.000 --> 0:12:06.679 to push for space flight. Now, that bit of information 0:12:06.720 --> 0:12:10.640 didn't reach the general American public, but you can bet 0:12:10.800 --> 0:12:13.480 that the federal government was very much aware of it. 0:12:14.040 --> 0:12:17.960 A year later, in nineteen fifty the US government announced 0:12:17.960 --> 0:12:20.480 a plan to launch a satellite, and that timing is 0:12:20.600 --> 0:12:25.080 definitely not a coincidence. The government began to request proposals 0:12:25.120 --> 0:12:29.720 from various laboratories to assist in getting this done, essentially saying, 0:12:30.280 --> 0:12:32.320 give us your plan so we can figure out where 0:12:32.320 --> 0:12:35.640 we're going to put our money. The Naval Research Laboratory 0:12:35.720 --> 0:12:40.080 responded to this request for proposals with a project called Vanguard, 0:12:40.440 --> 0:12:44.080 while other groups had alternative proposals and lacking a real 0:12:44.200 --> 0:12:47.880 sense of urgency, the White House kind of waffled on this. 0:12:47.960 --> 0:12:50.640 They delayed on selecting an option. They were kind of 0:12:50.679 --> 0:12:54.440 weighing all of the choices, and this was somewhat understandable 0:12:54.480 --> 0:12:59.360 as any path was going to require millions of taxpayer dollars, 0:12:59.400 --> 0:13:02.080 so if the project was a success, it would be 0:13:02.120 --> 0:13:05.160 a high point in science history. But if it failed, 0:13:05.720 --> 0:13:09.160 taxpayers would get mighty miffed at what had been seen 0:13:09.200 --> 0:13:12.520 as a huge waste of money, Like you took millions 0:13:12.520 --> 0:13:14.600 of our dollars and you put it towards something that 0:13:14.640 --> 0:13:18.240 didn't even work. That would be disastrous. Ultimately, the White 0:13:18.240 --> 0:13:21.560 House chose Project Vanguard, and the hope was to be 0:13:21.640 --> 0:13:24.920 the first nation to launch a man made satellite into orbit. 0:13:25.800 --> 0:13:29.000 But that's not how things turned out. While Project Vanguard 0:13:29.080 --> 0:13:33.120 was underway, the Soviets had been busy, and on October fourth, 0:13:33.400 --> 0:13:38.439 nineteen fifty seven, the USSR shocked the world by launching 0:13:38.480 --> 0:13:43.199 a nearly four pound or eighty three point six kilogram 0:13:43.360 --> 0:13:48.400 satellite into orbit. That satellite's name was Sputnik. It was 0:13:48.480 --> 0:13:51.480 about the size of a beach ball, and it would 0:13:51.559 --> 0:13:53.880 orbit the Earth every hour and a half or so, 0:13:54.440 --> 0:13:58.120 and it also essentially went beep. It sent out a 0:13:58.240 --> 0:14:00.960 radio ping signal that could be picked up by radio 0:14:01.120 --> 0:14:06.160 stations as the satellite passed overhead. That included radio sets 0:14:06.160 --> 0:14:10.440 that were operated by amateurs, so ham radio operators could 0:14:10.480 --> 0:14:14.800 hear as the satellite passed over and this launch shocked 0:14:14.960 --> 0:14:18.160 the American public. Americans were under the belief that the 0:14:18.200 --> 0:14:21.600 Soviet Union was far behind the United States from a 0:14:21.640 --> 0:14:26.480 scientific and technological standpoint. Spot Nik flew in the face 0:14:26.560 --> 0:14:29.960 of that, and it also raised a terrifying possibility. If 0:14:30.000 --> 0:14:33.520 the USSR could launch a payload into space, could it 0:14:33.640 --> 0:14:36.280 also create a weapon that could be fired from across 0:14:36.360 --> 0:14:40.240 the world and still hit the United States. Spot Nik 0:14:40.400 --> 0:14:44.520 launch spurred the U s Government into emergency mode. Vanguard 0:14:44.600 --> 0:14:46.880 was still on the books, but the White House would 0:14:46.920 --> 0:14:50.760 turn to the Army Redstone Arsenal Team led by one 0:14:51.160 --> 0:14:54.600 Werner von Braun for an alternative, and it would be 0:14:54.640 --> 0:14:57.960 called the Explorer one, and it would become the first 0:14:58.000 --> 0:15:01.320 satellite launched by the United Dates. We have a bit 0:15:01.320 --> 0:15:03.120 more history to go through when we come back, but 0:15:03.200 --> 0:15:05.960 after that we'll go into how we get these satellites 0:15:05.960 --> 0:15:09.200 into orbit, and then how they communicate with each other 0:15:09.240 --> 0:15:11.680 and with stations here on Earth. But first let's take 0:15:11.920 --> 0:15:22.640 a quick break. The first Spotnik satellite orbited the Earth 0:15:22.800 --> 0:15:26.200 in October nineteen fifty seven, and it was never intended 0:15:26.240 --> 0:15:30.400 to be a permanent fixture. It's orbit gradually decayed until 0:15:30.520 --> 0:15:33.840 in January nineteen fifty eight, it burned up while re 0:15:34.000 --> 0:15:37.240 entering the Earth's atmosphere. The Soviets launched spot Nick two 0:15:37.360 --> 0:15:40.720 in November of nineteen fifty seven, and that's all I'm 0:15:40.760 --> 0:15:43.520 going to say about that story. I've covered it before, 0:15:43.680 --> 0:15:46.680 and that story makes me super sad and I hate 0:15:46.720 --> 0:15:50.200 to talk about it. So the United States would launch 0:15:50.320 --> 0:15:54.480 Explorer one on January thirty one, nineteen fifty eight, So 0:15:54.600 --> 0:15:57.760 several months after both spot Nik and spot Nick two, 0:15:58.280 --> 0:16:02.280 it did more than beep. Explore one did not just beep. 0:16:02.360 --> 0:16:05.360 It also didn't kill a dog, So that's two things 0:16:05.400 --> 0:16:08.160 that made it more advanced than either of the Sputnik satellites. 0:16:08.800 --> 0:16:13.160 It carried scientific equipment designed to detect cosmic rays, and 0:16:13.200 --> 0:16:16.320 the fact that it sent data with lower cosmic raid 0:16:16.400 --> 0:16:20.520 counts than was anticipated. Let a scientist named James Van 0:16:20.600 --> 0:16:23.920 Allen to hypothesize about the existence of a belt of 0:16:24.080 --> 0:16:28.040 charged particles that were trapped by Earth's magnetic field. A 0:16:28.120 --> 0:16:32.040 second satellite confirmed this hypothesis a couple of months later, 0:16:32.120 --> 0:16:35.840 and the scientific community would name the charged particles the 0:16:35.960 --> 0:16:40.320 Van Allen Belts. It took Explore one just under one 0:16:40.800 --> 0:16:44.160 fifteen minutes to complete an orbit around the Earth, so 0:16:44.320 --> 0:16:46.880 it would go around the planet about twelve and a 0:16:46.960 --> 0:16:50.200 half times per day. It stayed in orbit a little 0:16:50.200 --> 0:16:53.320 longer than Sputnik did. While the Soviet satellite burned up 0:16:53.320 --> 0:16:56.000 on reentry just a few months after being launched, the 0:16:56.080 --> 0:17:01.480 Explorer one remained in orbit from ninety eight until eighteen seventy. 0:17:01.520 --> 0:17:06.879 It completed fifty eight thousand trips around Earth. The era 0:17:07.040 --> 0:17:10.000 of the satellite was just beginning. While a lot of 0:17:10.040 --> 0:17:15.000 media attention would shift towards space flights with humans and spacecraft, 0:17:15.000 --> 0:17:18.280 the scientific community around the world continued to develop new 0:17:18.359 --> 0:17:22.480 satellites for all sorts of purposes, from scientific research to 0:17:22.720 --> 0:17:27.840 military reconnaissance to eventually global communications. One other thing I 0:17:27.880 --> 0:17:30.840 want to mention before getting into the communications tech is 0:17:30.880 --> 0:17:34.200 how a science fiction author proposed a type of satellite 0:17:34.200 --> 0:17:38.000 that would be capable of communicating with a ground station 0:17:38.680 --> 0:17:41.119 every hour of the day. See, if you have a 0:17:41.119 --> 0:17:44.240 satellite in orbit like Explorer one, there's going to be 0:17:44.320 --> 0:17:47.639 times when that satellite cannot send communications back to a 0:17:47.720 --> 0:17:51.560 specific ground station because it's going to be out of sight. 0:17:52.080 --> 0:17:56.320 Once the satellite passes a certain point overhead, communications will 0:17:56.359 --> 0:17:59.719 start to drop. Placing ground stations around the world can 0:17:59.760 --> 0:18:02.159 saw of that problem, but that gets into the issue 0:18:02.160 --> 0:18:06.720 of establishing listening stations in places that you know aren't yours, 0:18:07.000 --> 0:18:11.040 and that gets tricky from a political and real estate standpoint. 0:18:11.200 --> 0:18:13.640 But obviously, if a satellite is on the opposite side 0:18:13.640 --> 0:18:16.880 of the Earth from a listening station, the radio signals 0:18:16.960 --> 0:18:19.920 can't get to the listening station, so you really only 0:18:19.960 --> 0:18:24.119 have a window where you can have useful communications with 0:18:24.200 --> 0:18:28.800 that particular type of satellite. For an effective communication satellite, 0:18:28.840 --> 0:18:31.679 you need something in orbit that will remain over the 0:18:31.760 --> 0:18:36.040 same fixed point here on Earth or in a pattern 0:18:36.119 --> 0:18:39.119 that keeps it over the same general area of the Earth. 0:18:39.480 --> 0:18:42.240 The satellite would need to travel around an orbital path 0:18:42.480 --> 0:18:45.240 that keeps pace with the rotation of the Earth itself, 0:18:45.560 --> 0:18:49.880 and this is called a geosynchronous orbit. The satellite will 0:18:49.880 --> 0:18:52.320 travel over the same general region of the Earth because 0:18:52.359 --> 0:18:55.040 it will orbit at the rate of once per day, 0:18:55.640 --> 0:18:59.520 the same as the Earth's rotation. Now, science fiction author 0:18:59.640 --> 0:19:02.919 Arthur See Clark, known for writing stuff like two thousand 0:19:03.000 --> 0:19:06.439 one a Space Odyssey, made a sort of observation and 0:19:06.480 --> 0:19:10.720 prediction back in nine It was published in a magazine 0:19:10.760 --> 0:19:14.080 called Wireless World, and it proposed the idea of a 0:19:14.160 --> 0:19:19.040 geo stationary satellite. Clark stated that a satellite at sufficient altitude, 0:19:19.400 --> 0:19:22.879 and he was talking about a an altitude of forty 0:19:22.880 --> 0:19:26.480 two thousand, one sixty four kilometers or around thirty five thousand, 0:19:26.560 --> 0:19:31.320 seven eighty seven miles above the Earth's surface and placed 0:19:31.359 --> 0:19:34.879 over the equator would have an orbital period equal to 0:19:34.920 --> 0:19:38.359 the Earth's rotation, and so would remain above the same 0:19:38.440 --> 0:19:43.359 fixed point on the equator. Now, forty two thousand, sixty 0:19:43.400 --> 0:19:48.720 four kilometers altitude is obviously a lot, but without any context, 0:19:48.840 --> 0:19:52.160 it's hard to say that's not so bad or wow, 0:19:52.400 --> 0:19:55.440 that's way the heck out there. So just for comparison's sake, 0:19:55.720 --> 0:19:58.760 it's good to remember that the International Space Station, which 0:19:58.960 --> 0:20:01.960 isn't in geo sin grannous orbit, is a mirror four 0:20:02.080 --> 0:20:07.719 hundred kilometers in altitude typically four hundred versus forty two thousand, 0:20:07.880 --> 0:20:12.720 one d sixty four. Wow. Still as far out as 0:20:12.840 --> 0:20:17.880 geosynchronous orbital areas are. That's not even halfway to the Moon. 0:20:18.000 --> 0:20:21.920 The Moon is three four thousand, four hundred kilometers from Earth, 0:20:22.600 --> 0:20:27.399 So a geostationary orbit is a specific subset of orbits 0:20:27.480 --> 0:20:31.440 that fall into the geosynchronous orbit category. A satellite in 0:20:31.520 --> 0:20:35.280 geosynchronous orbit will remain over a general region of Earth, 0:20:35.440 --> 0:20:39.399 but if the satellite isn't directly above the equator, that 0:20:39.600 --> 0:20:42.720 region varies a bit due to the Earth's tilt. In fact, 0:20:43.400 --> 0:20:45.920 from the Earth's standpoint, it looks like the satellite is 0:20:45.960 --> 0:20:50.160 moving in a figure eight pattern across the Earth's surface. 0:20:50.560 --> 0:20:53.680 That's because the path of the satellite crosses above and 0:20:53.800 --> 0:20:57.240 below the equator during the orbit and the Earth's rotation 0:20:57.359 --> 0:21:00.159 throughout the day. A geo stationary orbit has to be 0:21:00.359 --> 0:21:03.360 above the equator, and a satellite along that orbital path 0:21:03.640 --> 0:21:07.960 will remain over its fixed point on Earth. Uh with 0:21:08.200 --> 0:21:11.360 some caveats that I'll get to. Such a satellite could 0:21:11.400 --> 0:21:15.360 remain in constant contact with the exact same ground stations, 0:21:15.680 --> 0:21:18.360 and those ground stations would never need to move their 0:21:18.400 --> 0:21:21.800 antenna to maintain contact, right they would just point their 0:21:21.840 --> 0:21:24.480 antenna where the satellite is, and that's where the satellite 0:21:24.520 --> 0:21:27.880 is going to stay. So it really makes it simplified 0:21:28.000 --> 0:21:31.800 to communicate with that particular satellite. A network of those 0:21:31.840 --> 0:21:34.840 types of satellites could communicate with one another as well 0:21:34.920 --> 0:21:37.320 as their respective ground stations, and boom, you've got your 0:21:37.359 --> 0:21:41.840 framework for a global communications infrastructure using radio signals beamed 0:21:41.880 --> 0:21:45.119 out into space and then beamed back down to the Earth. Now, 0:21:45.240 --> 0:21:48.440 Clark's idea was sound, but there wasn't really any practical 0:21:48.520 --> 0:21:52.520 way to achieve it. Back in it would take twenty 0:21:52.640 --> 0:21:55.359 years before the world would see the first commercial geo 0:21:55.480 --> 0:21:59.800 stationary communications satellite, and that was called the Intel SAT one. 0:22:00.440 --> 0:22:02.640 I think it would be handy for us to look 0:22:02.680 --> 0:22:06.560 at what makes putting satellites into geo stationary orbits so tricky, 0:22:06.880 --> 0:22:09.280 because it gives us an appreciation for the amount of 0:22:09.400 --> 0:22:13.320 science and technology required to make stuff like communication networks 0:22:13.680 --> 0:22:19.200 actually work. So let's start with just putting something into orbit. First, 0:22:19.400 --> 0:22:22.199 you gotta put your satellite on a launch vehicle. Now, 0:22:22.359 --> 0:22:24.960 essentially what we're talking about is a rocket. Now, back 0:22:25.000 --> 0:22:27.560 in the old days, it was the Space Shuttle. We 0:22:27.680 --> 0:22:30.160 often use the Space Shuttle to put satellites up into orbit, 0:22:30.280 --> 0:22:32.960 and the Space Shuttle had rocket boosters attached to it 0:22:33.040 --> 0:22:36.200 as well as its own rocket engine. But these days 0:22:36.240 --> 0:22:38.520 we don't have a space Shuttle. We're talking about a 0:22:38.600 --> 0:22:42.359 rocket here. Usually from our perspective, we launch those rockets 0:22:42.640 --> 0:22:45.680 straight up from the Earth's surface. And there's a good 0:22:45.760 --> 0:22:48.720 reason for this when you think about it. If you're 0:22:48.760 --> 0:22:52.840 looking anywhere from above the horizon in one direction across 0:22:52.920 --> 0:22:55.760 the entire arc of the sky to the horizon, and 0:22:55.840 --> 0:22:58.520 the other direction. So let's say you're doing it from 0:22:58.560 --> 0:23:00.720 east to west. Well, the whole time you do that, 0:23:00.880 --> 0:23:04.000 you're technically looking out towards space. So why would you 0:23:04.080 --> 0:23:08.320 launch straight up if every direction in that arc is 0:23:08.560 --> 0:23:11.760 out towards space. What's because the shortest distance between two 0:23:11.800 --> 0:23:15.400 points is a straight line, and launching straight up means 0:23:15.440 --> 0:23:18.960 you're taking the shortest path to push through the thickest 0:23:19.000 --> 0:23:21.800 part of the atmosphere. You're doing it in the most 0:23:21.880 --> 0:23:25.480 efficient way, and that's really important because that means you're 0:23:25.480 --> 0:23:29.560 consuming less fuel. Since fuel is one of the expensive 0:23:29.640 --> 0:23:33.800 factors in space launches, and since adding more fuel adds 0:23:33.920 --> 0:23:36.520 more weight to your launch vehicle, which means you then 0:23:36.600 --> 0:23:40.560 have to factor that weight into your calculations, being frugal 0:23:41.040 --> 0:23:44.879 with stuff is generally a really good idea. Once the 0:23:45.000 --> 0:23:48.960 rocket reaches a certain altitude, the flight plan will call 0:23:49.280 --> 0:23:52.000 for the rocket to adjust its direction so that the 0:23:52.040 --> 0:23:55.520 payload our satellite in other words, gets to where it's 0:23:55.520 --> 0:23:58.639 supposed to be, and a system called the inertial guidance 0:23:58.800 --> 0:24:01.840 system will calculate the specific adjustments needed to put the 0:24:01.920 --> 0:24:06.600 rocket on the correct path. That system uses accelerometers to 0:24:06.920 --> 0:24:10.400 measure the various stresses it's experiencing in order to interpret 0:24:10.520 --> 0:24:14.359 that as how the rocket is oriented with respect to 0:24:14.400 --> 0:24:17.719 the Earth and what altitude it's at. Those accelerometers are 0:24:17.800 --> 0:24:20.439 in gimbals so that they remain in the same orientation 0:24:20.520 --> 0:24:23.600 with respect to the Earth. Typically, the rocket will head 0:24:23.880 --> 0:24:27.959 toward the east once it reaches that altitude. So why 0:24:28.040 --> 0:24:30.320 does it go toward the east was because the Earth 0:24:30.440 --> 0:24:33.159 rotates to the east, and by going in that direction, 0:24:33.240 --> 0:24:37.120 the rocket gets a bit of a boost, and you'd 0:24:37.160 --> 0:24:39.639 get the best boost in speed if you happen to 0:24:39.720 --> 0:24:43.280