Speaker 1: Welcome to tech Stuff, a production from My Heart Radio.
Speaker 1: Hey there, and welcome to tech Stuff. I'm your host,
Speaker 1: Jonathan Strickland. I'm an executive producer with my Heart Radio
Speaker 1: and how the Tech Area. It is time for a
Speaker 1: tech Stuff classic episode. This episode originally published back on
Speaker 1: December nine, two thousand fifteen. It is titled how Satellites Work. Enjoy.
Speaker 1: Let's talk about satellites and what they are. So satellite
Speaker 1: is something that's in orbit around another object. And of
Speaker 1: course Earth has had a satellite for billions of years.
Speaker 1: That would be the Moon. That's a natural satellite. But
Speaker 1: if we want to look at man made satellites, we
Speaker 1: have to go back a few decades. And in fact,
Speaker 1: the foundation for man made satellites, the principles, the idea
Speaker 1: of what would be required go act well before the
Speaker 1: space race ever started. That would be Isaac Newton who
Speaker 1: came up with the idea of what would be required
Speaker 1: to create a satellite. Now that's not what he necessarily
Speaker 1: called it, but this was published in a famous thought
Speaker 1: experiment back in seventeen twenty nine, and at the time
Speaker 1: he was really concentrating on gravity, which is pretty heavy stuff.
Speaker 1: So Newton's thought experiment was famous. People have talked about
Speaker 1: this a lot. You've probably heard about it. He said,
Speaker 1: what if you were to go at the top of
Speaker 1: a really really tall mountain and you build a cannon
Speaker 1: on the top of that mountain, and you aim that
Speaker 1: cannon so that the barrel is parallel with the earth
Speaker 1: below you, so it's at at the same you know,
Speaker 1: same angle as the ground down at the base of
Speaker 1: the mountain. You fire the cannon, the cannon ball flies
Speaker 1: out and it moves away from the cannon, and but
Speaker 1: it also starts to fall because gravity has been pulling
Speaker 1: on the cannonball the whole time. You know, gravity was
Speaker 1: pulling on the cannonball when it was in the cannon.
Speaker 1: It's pulling on the cannonball now that it's emerged from
Speaker 1: the cannon. Eventually, this cannonball is going to fall to
Speaker 1: the ground. And by eventually, it's it's based upon the
Speaker 1: altitude that the cannonball already is at. Uh doesn't have
Speaker 1: anything to do with the forward velocity so much as
Speaker 1: the altitude. He said, well, what if you were to
Speaker 1: to pack more gunpowder in this cannon and you fire it,
Speaker 1: might it will go further because it's moving out a
Speaker 1: forward velocity. That's that's greater than the previous one, but
Speaker 1: it still will eventually fall to the earth. Uh really
Speaker 1: in that same amount of time. It's just gonna be
Speaker 1: further out from their first shot. But then you keep
Speaker 1: packing more and more gunpowder in, and eventually you pack
Speaker 1: enough gunpowder in so that when you fire the cannonball,
Speaker 1: it is flying out at a forward velocity at a
Speaker 1: at a rate that is equal to how the Earth
Speaker 1: is curving a way from the cannonball. So, in other words,
Speaker 1: the canniballs falling toward the Earth, but the Earth is
Speaker 1: curving away from the cannonball at that same rate, so
Speaker 1: the cannibal never falls down to hit the Earth's surface
Speaker 1: because the Earth is falling away from the cannonball at
Speaker 1: the same rate that the cannonball itself is falling. This
Speaker 1: would mean that eventually you would shoot yourself in the back,
Speaker 1: because the cannonball would make a full rotation around the
Speaker 1: Earth and come back to its point of origin. At least,
Speaker 1: that was the thought experiment that Newton had proposed, which
Speaker 1: seemed like a really clever idea, but there was no
Speaker 1: practical means of testing it or putting it to any
Speaker 1: use back in Newton's day, it was just an interesting idea.
Speaker 1: It would not be until October four, nineteen seven, and
Speaker 1: that's when the then Soviet Union made history by launching
Speaker 1: the first man made satellite into Earth orbit, and that
Speaker 1: satellite was the spot Nick one. But it was fairly simple.
Speaker 1: It was a ball all that was silver in color.
Speaker 1: It was about twenty two point eight inches in diameter,
Speaker 1: which is around fifty eight centimeters, so not very big,
Speaker 1: and it weighed a hundred eighty three point nine pounds
Speaker 1: or eighty three point six ms. The body was made
Speaker 1: out of an aluminum alloy, and the shell of that
Speaker 1: aluminum was just two millimeters thick. It was actually two
Speaker 1: hemispheres of a globe that were connected together by thirty
Speaker 1: six bolts around the circumference of those hemispheres. It had
Speaker 1: two antennas, and each antenna had two beams, so like
Speaker 1: four prongs extending backward from the scent from the sphere itself,
Speaker 1: almost like it had four legs. One pair of antenna
Speaker 1: where seven point nine feet long or about two point
Speaker 1: four meters. The other pair was twelve point eight feet
Speaker 1: long or three point nine meters. Inside the satellite. There
Speaker 1: wasn't a whole lot, not compared to what had originally
Speaker 1: been planned to put in the satellite. Inside it was
Speaker 1: a radio transmitter so it could communicate back to Earth,
Speaker 1: had three silver zinc batteries that would provide power. It
Speaker 1: had a couple of different switches inside of it, remote switches,
Speaker 1: a thermal system fan was in there, a controlled thermal switch,
Speaker 1: and a barrel metric switch. We're in there. So and
Speaker 1: it was also filled with nitrogen gas to create internal pressure. Essentially,
Speaker 1: the only things this this was really the only thing
Speaker 1: this this um satellite could do was monitor its own
Speaker 1: systems like how hot was it or cold was it?
Speaker 1: What was the pressure like, and then it would beam
Speaker 1: down information in a series of beeps. In fact, my
Speaker 1: former co host Chris Palette used to refer to spot
Speaker 1: Nick as the thing what beeps. It actually sounded a
Speaker 1: bit like this. So if you had had a Ham
Speaker 1: radio back in nine and you were tuning in, you
Speaker 1: could actually pick up that signal as sput Nick passed
Speaker 1: overhead because it was broadcasting on a frequency that was
Speaker 1: within the citizen band radio frequency, and that meant that
Speaker 1: people could actually listen in as sput Nick went overhead.
Speaker 1: It only took ninety eight minutes for the satellite to
Speaker 1: go around the Earth, so every hour and a half
Speaker 1: or so you would be able to pick this up.
Speaker 1: And it freaked people out, particularly in the United States.
Speaker 1: People were freaking out because they were able to actually
Speaker 1: hear evidence of the Soviet Union's ability to send an
Speaker 1: object into space. And if they could do that, there
Speaker 1: was also the fear that they could perhaps fire a
Speaker 1: ballistic missile, maybe with a nuclear warhead, at the United
Speaker 1: States that they had had now had the capability to
Speaker 1: fire massive destructive weapons at the US from a world away,
Speaker 1: and at this time the Cold War was going on strong.
Speaker 1: So it caused more than a little stir. It was
Speaker 1: the fuel for tons of different science fiction films. Uh,
Speaker 1: They're all these different U instructional movies that explained what
Speaker 1: you need to do in the case of a nuclear war,
Speaker 1: and most of them were freakishly optimistic. At any rate,
Speaker 1: it propelled the United States into a new era of
Speaker 1: research and development. The US had already been planning on
Speaker 1: getting into the space race, but this meant that suddenly
Speaker 1: everything was cranked up to eleven, as spinal tap would say.
Speaker 1: So it really literally launched the space race between the
Speaker 1: United States and the Soviet Union. Now, for the story
Speaker 1: of spot Nick itself, you actually have to go back
Speaker 1: much further back to the nineteen forties in fact, or
Speaker 1: even earlier, when you're looking at the the rocket program
Speaker 1: out of the Soviet Union during World War Two. So
Speaker 1: officially you would argue that nineteen fifty two was was
Speaker 1: what got Sputnik itself going. Within the Soviet Union, that's
Speaker 1: what an organization called the International Council of Scientific Unions
Speaker 1: called for artificial satellites to be launched in order to
Speaker 1: study solar activity, which was going to be reaching a
Speaker 1: peak in nineteen fifty eight, and the United States started
Speaker 1: planning a launch at least as far back as nineteen
Speaker 1: fifty five, and their project was called Vanguard, and pretty
Speaker 1: much the world was looking at the United States as
Speaker 1: the leader. It was going to be the US that
Speaker 1: would be launching a satellite sometime around the summer of
Speaker 1: nineteen fifty seven. But the Soviet Union thought, hey, we
Speaker 1: have the opportunity to show up our rival, and so
Speaker 1: they really put Sputnik on the fast track now to
Speaker 1: to look at what was going on in the Soviet Union.
Speaker 1: Going back to the nineties, there was a man named
Speaker 1: Mikhail tiken Revov. I'm gonna mess up that name all
Speaker 1: the time. Tick Hanravov who led a team of scientists
Speaker 1: to design, build, and launch spot Nick one. But their
Speaker 1: early work was really looking at missile systems, ballistic missile
Speaker 1: missile systems for military use. Uh, they just saw the
Speaker 1: potential for using those same systems to launch satellite into space.
Speaker 1: And they were really looking at the possibility of using
Speaker 1: multi stage rockets in order to get the right amount
Speaker 1: of acceleration to push an object into orbit. And they
Speaker 1: were often relying on research performed not just by their team,
Speaker 1: but by other scientific teams around the world. Often this
Speaker 1: was information that we're that was pulled in through espionage.
Speaker 1: It wasn't necessarily the scientific community openly sharing this information.
Speaker 1: And originally, uh, they were really looking at how can
Speaker 1: we make missiles better missiles for the Soviet Union. The
Speaker 1: group would form in nineteen forty six, so not long
Speaker 1: after the end of World War Two, and the team
Speaker 1: worked on satellite plans pretty much in secret because they
Speaker 1: weren't sure if the Soviet government would actually appreciate their
Speaker 1: interest in scientific research that did not have an immediate
Speaker 1: military application. Now, keep in mind that until nineteen fifty three,
Speaker 1: the Soviet Union was being led by Joseph Stalin, and
Speaker 1: he was an incredibly brutal dictator, and paranoia was rampant
Speaker 1: in the Soviet Union. There were stories about secret police
Speaker 1: and kidnappings in the middle of the night. People lived
Speaker 1: in constant fear of being arrested or executed. But after
Speaker 1: Stalin died in March ninette, people were able to concentrate
Speaker 1: on something beyond just not being noticed. It's hard to
Speaker 1: imagine how terrifying that time must have been, but it's
Speaker 1: probably no coincidence that it was nineteen fifty for when
Speaker 1: the Soviet scientists stopped hiding the fact that they were
Speaker 1: performing this satellite research. They would talk about it openly,
Speaker 1: and the project received support from various scientific societies within
Speaker 1: the USSR, but it wouldn't be until nineteen fifty six
Speaker 1: that they received official approval from the Kremlin. So if
Speaker 1: you want to hear a really amazing story about bureaucracy, science, politics,
Speaker 1: and how messed up everything was in the Soviet Union
Speaker 1: in the nineteen fifties, you should really research the full
Speaker 1: story of spot Nik because it's amazing that this project
Speaker 1: ever really got a lot of of support. In large
Speaker 1: part the support was coming from the Soviet Union wanting
Speaker 1: to demonstrate its power, not to pursue science, but in
Speaker 1: order to show the rest of the world we're the
Speaker 1: big bear, don't mess with us. There were a whole
Speaker 1: bunch of different departments. It all worked on the design
Speaker 1: of the spot Nick project, and it's kind of interesting
Speaker 1: to see how diverse this group was. So those those
Speaker 1: different departments included the Academy of Sciences of USSR, which
Speaker 1: oversaw the scientific research and development of the project. There
Speaker 1: was the organization Okay b DASH one, which was the
Speaker 1: u s s R Experimental Design Bureau. It's essentially was
Speaker 1: the equivalent of our DARPA here in the United States.
Speaker 1: It was a research and development program that really took
Speaker 1: big risks to see if they could find big reward
Speaker 1: from scientific research implemented in practical ways. That particularly, that
Speaker 1: particular department fell under the direction of the Ministry of
Speaker 1: Defense Industry. So that group was responsible for designing the
Speaker 1: body of the satellite, and in the Satellite biz we
Speaker 1: referred to this as the bus. The bus is essentially
Speaker 1: the the body or shell inside which all the instrumentation
Speaker 1: exists apart from you know, some instrumentation obviously has to
Speaker 1: be on the outside of the bus, like any sort
Speaker 1: of imagery or antenna, but you get what I mean. Next,
Speaker 1: we have the Ministry of Radio Industry. They were in
Speaker 1: charge of flight control systems, radio and telemetry systems. Then
Speaker 1: you had the Ministry of ship Building. The ship Building
Speaker 1: Ministry was responsible for designing the gyroscopes that would go
Speaker 1: in the satellite. You had the Ministry of Machine Building.
Speaker 1: They were responsible for ground processing, transport, fueling, and launch hardware.
Speaker 1: You had the Ministry of Defense itself which was in
Speaker 1: charge of launch operations. You had the Ministry of Avia
Speaker 1: Aviation Industry which was in charge of the tracking systems,
Speaker 1: and the Special Committee of the Soviet of Ministers, which
Speaker 1: were all about the management and coordination of the program overall. Now,
Speaker 1: originally spot NICK was referred to as Object D and
Speaker 1: it was supposed to be a much larger, much more
Speaker 1: sophisticated satellite. It was not supposed to just be the
Speaker 1: thing what beeps. It was supposed to have a lot
Speaker 1: of instrumentation for actual scientific study, with a collection of
Speaker 1: useful instruments but the projects suffered several setbacks in the
Speaker 1: design process that kept pushing back when they would be
Speaker 1: able to launch, and there was a growing concern that
Speaker 1: the United States was going to be able to launch
Speaker 1: a satellite in orbit starting on July first nine. So
Speaker 1: they had a new goal. They wanted to strip down
Speaker 1: their ideas to just the most essential elements to try
Speaker 1: and beat America to the punch, and they did. They
Speaker 1: were able to create a much smaller, more basic satellite
Speaker 1: and they were able to launch it before the United
Speaker 1: States could send their own satellite into space, and they
Speaker 1: set a precedent, and in fact, only did the USSR
Speaker 1: beat the USA, they did it twice. We'll be back
Speaker 1: with more of this classic episode about how satellites work
Speaker 1: after this quick break. The second satellite, which was Sputnik two,
Speaker 1: contained the first life form sent into Earth orbit, and
Speaker 1: that was the dog named Lyca, and Likeca, was always
Speaker 1: destined to die during this mission. There was no plan
Speaker 1: for Lyca to return to Earth safely. Uhlica was going
Speaker 1: to die inside the satellite, either by starvation or thirst.
Speaker 1: It was just no or suffocation that was just known
Speaker 1: that this was a one way trip for the dog. Um,
Speaker 1: the dog likely died due to overheating fairly early in
Speaker 1: the mission based upon what the instrumentation was saying. And
Speaker 1: there have been a lot of web comics, cartoons and
Speaker 1: an amazing song. More than one song, but there's a
Speaker 1: great song called Space Doggedy which was written by Jonathan
Speaker 1: Colton and obviously has uh a lot of influence from
Speaker 1: Space Oddity from David Bowie Space Oddity in there. Space
Speaker 1: Doggy great song. There's actually a video on YouTube someone's
Speaker 1: put together with actual footage of like a from spot
Speaker 1: Nick two. And that's all I'm going to say about that,
Speaker 1: because otherwise I'm gonna get all choked up because to me,
Speaker 1: it's a very sad story and necessary story. I totally
Speaker 1: understand why we need to use animals to test the systems,
Speaker 1: because clearly you can't just put a human in there
Speaker 1: and hope everything turns out all right. But it's still
Speaker 1: a very sad story to me because I'm I'm a
Speaker 1: squishy dog lover. I have a dog, and I when
Speaker 1: I look at my dog and imagine what Lica was
Speaker 1: going through, I just fall to pieces. At any rate,
Speaker 1: the United States response to sput Nick was to go
Speaker 1: back to the drawing board. They had their Vanguard design
Speaker 1: mind that they had planned to launch, but that now
Speaker 1: felt that it was no longer a strong enough offering.
Speaker 1: They needed to come up with a better satellite to
Speaker 1: really be a good response to the Soviet Union's project.
Speaker 1: So the new USA project was called Explorer, and it
Speaker 1: was led by a rocket scientist named Werner von Brown.
Speaker 1: Von Brown was a brilliant physicist, a very intelligent rockets scientist,
Speaker 1: but he had an incredibly dark past. UH. He was
Speaker 1: born in Germany in nineteen twelve and he was part
Speaker 1: of the Rocket Society as early as nineteen twenty nine.
Speaker 1: As the Nazis gained power in Germany during the thirties,
Speaker 1: Von Brown chose to work for the German Army to
Speaker 1: develop missiles. He wanted to continue his research and work,
Speaker 1: and it seemed like the UH the most opportune place,
Speaker 1: and his work was instrumental in the development of the
Speaker 1: V two ballistic missile, which was a tool the Nazis
Speaker 1: used to some effect, perhaps not as great as it
Speaker 1: could have been, but certainly was a destructive weapon that
Speaker 1: caused a lot of damage and death. He was eventually
Speaker 1: awarded an honorary rank in the s S by Heinrich Himmler.
Speaker 1: It is said, however, that von Brown only accepted that
Speaker 1: rank because he and his team were worried that Himmler
Speaker 1: would be angry if he had declined it. So at
Speaker 1: least some accounts state that von Brown didn't share the
Speaker 1: political ideology of the Nazis. He just saw this as
Speaker 1: the opportunity for him to actually do his work, and
Speaker 1: if he didn't join the Nazis then he would not
Speaker 1: be able to do his work. Von Brown realized that
Speaker 1: Germany would lose the war. I think a lot of
Speaker 1: people realized that it was getting to a point where
Speaker 1: it was deniable, and so he made plans to surrender
Speaker 1: himself and his team of around five rockets scientists to
Speaker 1: the Allies and offered to do research for the United
Speaker 1: States to help them develop their ballistic missiles. Further So,
Speaker 1: Fan Brown and his scientists would create a rocket research
Speaker 1: center that originally fell under the guidance of the United
Speaker 1: States Army, but eventually it would get shifted to a
Speaker 1: new organization called NASA, which was founded mainly in reaction
Speaker 1: to spot Nick and really be part of the space race.
Speaker 1: Explorer one would launch on January thirty one, nineteen eight,
Speaker 1: and it made an actual scientific discovery on its orbital flight.
Speaker 1: It discovered magnetic radiation belts around the Earth, which are
Speaker 1: now called the Van Allen Belt after one of the
Speaker 1: lead researcher on the project. Now, these days, satellites are
Speaker 1: way more sophisticated than spot Nick or even Explorer one,
Speaker 1: and they typically use solar panels to capture solar energy
Speaker 1: and convert it into electricity that's used to charge batteries
Speaker 1: for power. Some of them actually use fuel cells rather
Speaker 1: than batteries to generate electricity, And we've used nuclear power
Speaker 1: in some probes that we've sent away from our planet,
Speaker 1: but in general we tend to be a bit skittish
Speaker 1: about the idea of putting nuclear power into stuff that's
Speaker 1: going to be orbiting our own planet. Satellites tend to
Speaker 1: have some pretty sophisticated stuff inside them these days, like
Speaker 1: computer control systems, which were well beyond the abilities of
Speaker 1: the early satellites which had electro mechanical controls. But now
Speaker 1: we've got computer control systems, radio communications, attitude control systems.
Speaker 1: Attitude in this case isn't about personality, but rather the
Speaker 1: satellites orientation with respect to the position of the Earth,
Speaker 1: and satellites can have different shaped orbits. Some have circular
Speaker 1: or bits, which are very regular and uh and predictable,
Speaker 1: but some have elliptical orbits. And elliptical orbits are interesting
Speaker 1: because a satellite will travel at different speeds along its
Speaker 1: orbital path. So there are two points along that path
Speaker 1: that we call the foci of the elliptical orbit. The
Speaker 1: point that's closest to the planet is the parage, and
Speaker 1: that's the point at which the satellite will be moving
Speaker 1: fastest through its orbit. It's like think of it like
Speaker 1: the sling shot effect. The furthest point from a planet.
Speaker 1: The furthest point in the orbit the satellite's orbit from
Speaker 1: a planet is the apogee, and that's where the satellite
Speaker 1: will move the slowest in its orbital path. Now, launching
Speaker 1: a satellite into orbit obviously requires rockets, and in a
Speaker 1: rocket launch, a special system is used called the inertial
Speaker 1: guidance system, which calculates the adjustments needed to push a
Speaker 1: satellite into the correct orbit. I'll talk about the different
Speaker 1: orbits in a second. Typically, rockets are fired so that
Speaker 1: they head eastward, and that means that the Earth's rotation
Speaker 1: gives those rockets a speed boost. It's like the rockets
Speaker 1: are actually flying faster than they really are because of
Speaker 1: the relative motion of the Earth. If you were to
Speaker 1: launch your rocket at the equator, you would get the
Speaker 1: biggest boost because the Earth bulge is out there. It's
Speaker 1: the largest diameter. So here's how you would determine the
Speaker 1: boost you get to your speed. You take the Earth's circumference,
Speaker 1: which is about two thousand, nine hundred miles or forty
Speaker 1: thousand sixty kilometers. You figure out how fast the Earth rotates,
Speaker 1: which is one full rotation in approximately twenty four hours,
Speaker 1: which gives us a speed of around one thousand, thirty
Speaker 1: eight miles per hour or one thousand, six hundred sixty
Speaker 1: nine kilometers per hour. That's the rotational speed of the Earth.
Speaker 1: That's typically that's actually at the equator. If you were
Speaker 1: to look at a launch facility at Cape Canaveral, the
Speaker 1: rotational speed is different because you're further north of the equator.
Speaker 1: You're not at the thickest part of the Earth. Uh Therefore,
Speaker 1: the circumference is smaller and you have a slower speed,
Speaker 1: So a slower rotational speed at that point so it's
Speaker 1: closer to around eight miles per hour or one thousand,
Speaker 1: four hundred forty kilometers per hour, but that speed boost
Speaker 1: gives us a big help. So to get the satellite
Speaker 1: into orbit, you have to be going wicked fast, but
Speaker 1: not as fast as what you would need to actually
Speaker 1: escape Earth's gravity. So if you wanted to go out
Speaker 1: into space and beyond Earth's gravity, you're leaving Earth orbit,
Speaker 1: you're heading out to Mars or something. You would have
Speaker 1: to accelerate to at least twenty five thousand, thirty nine
Speaker 1: miles per hour or forty kilometers per hour to escape
Speaker 1: Earth's gravity and enter outer space. Putting a satellite in
Speaker 1: orbit requires less speed, and it all depends upon which
Speaker 1: orbit you're trying to insert the satellite into. The orbits
Speaker 1: determine the speed, so lower orbits require faster speeds, which
Speaker 1: might seem counter and tuitive at first, but you gotta
Speaker 1: remember those lower orbits that that speed is meant to
Speaker 1: counteract the gravitational pull of Earth so that the object
Speaker 1: in orbit remains in orbit doesn't get pulled back down
Speaker 1: to the ground. So when you're closer to Earth, the
Speaker 1: force of gravity is greater, as you probably Remember, gravity
Speaker 1: is dependent upon two things, the mass of two objects
Speaker 1: and their relative distance to one another. So as distance
Speaker 1: increases gravitation, gravitational pull decreases, and you don't need to
Speaker 1: counteract that with more velocity to make sure an object
Speaker 1: stays within its orbital path and doesn't deteriorate and fall
Speaker 1: into the Earth. So higher orbits require lower speeds, and
Speaker 1: if you get far enough out there, you can have
Speaker 1: a satellite that orbits at the same speed as Earth's rotation. Uh,
Speaker 1: those would be geostationary orbits. They would appear to be
Speaker 1: directly above a fixed point on the Earth and they
Speaker 1: would not move from that point. I'll get into that
Speaker 1: more just a second. First, let's talk about the various
Speaker 1: types of orbits from an altitude, because we can describe
Speaker 1: orbits in different ways. You can describe their orbital pathway
Speaker 1: whether it's circular or elliptical. You can describe it in
Speaker 1: its altitude, and you can describe it in its orientation
Speaker 1: as in is it equatorial, is it directly above the equator?
Speaker 1: Is there any degree of inclination? Um? Is it a
Speaker 1: polar orbit which goes north south not east west? Lots
Speaker 1: of different ways to describe them. So from an altitude perspective,
Speaker 1: we start with lower orbit. That's the one closest end
Speaker 1: to the Earth, and that's an a range that's between
Speaker 1: a hundred eleven miles and one thousand, two hundred three
Speaker 1: miles above the surface of the Earth. In kilometers, I
Speaker 1: would be a hundred eighty to two thousand uh. This
Speaker 1: tends to be the altitude we use for satellites that
Speaker 1: collects surface observations, photography, weather satellites, that kind of thing.
Speaker 1: When you go further out, you get to medium Earth
Speaker 1: orbit that's in a zone the between one thousand, two
Speaker 1: hundred forty three miles and twenty two thousand, two hundred
Speaker 1: twenty three miles or in kilometers way easier two thousand
Speaker 1: to thirty six thousand kilometers. Navigation satellites like GPS tend
Speaker 1: to be at this altitude, although summer at higher altitudes.
Speaker 1: Then you get to geosynchronous orbit. That's when you are
Speaker 1: at an altitude that's greater than twenty two thousand, twenty
Speaker 1: three miles, in other words, greater than thirty six thousand kilometers.
Speaker 1: The orbital period is the same as the Earth's rotational period,
Speaker 1: meaning it takes a full day for the satellite to
Speaker 1: go all the way around the Earth. There are is
Speaker 1: a subset of geosynchronous satellites called geo stationary satellites, So
Speaker 1: all geostationary satellites are also geosynchronous, but not all geosynchronous
Speaker 1: satellites are geo stationary. If you have a geostationary satellite,
Speaker 1: that's one of those satellites that remains over a fixed
Speaker 1: position on the Earth's surface, So you could build and
Speaker 1: enter at that point pointed straight up into the atmosphere,
Speaker 1: and it's going to be aimed directly at that satellite.
Speaker 1: And as long as nothing changes in that satellite's orbit.
Speaker 1: Things do change over time, so you have to correct
Speaker 1: it occasionally, but as long as nothing changes, uh, the
Speaker 1: antenna and satellite will always be in alignment. That's a
Speaker 1: geostationary satellite. Uh. It doesn't matter if it's day or night.
Speaker 1: You're always going to have a direct line of sight
Speaker 1: between the antenna and the satellite, and the satellite is
Speaker 1: gonna be too far away from you to see it,
Speaker 1: but there's a direct line of site as far as
Speaker 1: the antenna is concerned. All geostationary satellites are geosynchronous. Like
Speaker 1: I said, But if the opposite isn't true, what's going on?
Speaker 1: How are geo secret as satellites that aren't geostationary. How
Speaker 1: does that work? Well, the geosynchronous satellite does make one
Speaker 1: orbit around the Earth in the same amount of time
Speaker 1: it takes Earth to make one rotation in inertial or
Speaker 1: fixed space, which is also called a sidereal day. It's
Speaker 1: actually not twenty four hours. Specifically, it is twenty three hours,
Speaker 1: fifty six minutes and four seconds of mean solar time.
Speaker 1: You've got a bit more to say about how satellites work,
Speaker 1: but before we get to that, we need to take
Speaker 1: another quick break. If the satellite has any inclination or
Speaker 1: a non circular orbital path, it will not be geo stationary.
Speaker 1: The satellite will appear to roam over the Earth's surface,
Speaker 1: so in elliptical orbits, those egg shaped orbits, the satellite
Speaker 1: would be moving at different speeds along its journey. Remember
Speaker 1: the paragean apogee, It's going to be moving it at
Speaker 1: different velocities as it goes around the Earth. Inclination, by
Speaker 1: the way, is the angle between a reference plane and
Speaker 1: the orbital plane. The reference plane in this case, Uh,
Speaker 1: we're talking specifically about the equator. So imagine you've got
Speaker 1: the Earth globe, you've got it tilted at a slight
Speaker 1: angle because the axis is on an angle, and you've
Speaker 1: got the equator. If you have a geosynchronous satellite directly
Speaker 1: above the equator, it's going to be geo stationary. It's
Speaker 1: going to stay around that fixed point. But if you
Speaker 1: go north or south of the equator and you place
Speaker 1: a satellite there, it will it will not stay above
Speaker 1: a fixed point. Its orbit is going to be slightly angled.
Speaker 1: That's the inclination we would talk about. UH, So as
Speaker 1: it would go around the pathway, uh, it would actually
Speaker 1: roam over the surface of the Earth. So a satellite
Speaker 1: that has degrees of inclination and its orbit with respect
Speaker 1: to the equator will move north and south of the
Speaker 1: equator as it completes an orbit. So this satellite is
Speaker 1: going to stay more or less in the same east
Speaker 1: west area, but it's going to go north south as
Speaker 1: it goes throughout its orbit. Satellites with an elliptical path
Speaker 1: will drift east and west for any fixed point on
Speaker 1: the Earth. As a satellite moves faster or slower through
Speaker 1: its Earth orbit. We have seen There are several satellites
Speaker 1: that use this where they are both a inclination and
Speaker 1: an elliptical path, so they make this almost like a
Speaker 1: figure eight kind of pattern over a general region of
Speaker 1: the Earth's surface, which could be really useful for things
Speaker 1: like communication satellites or or even GPS in that In
Speaker 1: that sense, there are some GPS satellites that work under
Speaker 1: this principle. Geo stationary satellites have a view of about
Speaker 1: of the Earth's surface. Just a single geo stationary satellite
Speaker 1: can see about fort of the Earth's surface from where
Speaker 1: it is. So if you just create a network of
Speaker 1: a few geostationary satellites, you can get a view of
Speaker 1: practically the entire Earth, really everything between eighty one degree
Speaker 1: south and eighty one degrees north. Beyond those those uh
Speaker 1: those degrees, you wouldn't be able to see it from
Speaker 1: the way the Earth is curved, but you'd get to
Speaker 1: see everything between the two. Geo stationary satellites tend to
Speaker 1: be used for communications. That's great solution for us on
Speaker 1: the ground because you don't need to move the antenna
Speaker 1: on the surface to stay in contact with the satellite.
Speaker 1: If the satellite we're drifting if it if it orbited
Speaker 1: the Earth multiple times during a rotation, you would constantly
Speaker 1: have to adjust your antenna to remain in contact with
Speaker 1: the satellite, and there will be times where you would
Speaker 1: be out of contact with the satellite. It would have
Speaker 1: the Earth between you and the antenna. So geo stationary
Speaker 1: makes this easy because it's always going to be directly
Speaker 1: above the antenna. So it makes an ideal communication satellite
Speaker 1: in that respect. But there are a limited number of
Speaker 1: slots for geostationary satellites. You know, you could go to
Speaker 1: different altitudes, but you're going to be You're going to
Speaker 1: be stuck at that equator plane. So you don't want
Speaker 1: satellites to collide with one another. Obviously, that would destroy
Speaker 1: or an least damage one or both satellites, and you
Speaker 1: don't want the actual data communication to interfere with each other,
Speaker 1: so you have to separate them out by space. You
Speaker 1: can't have them to pack pecked in too closely together,
Speaker 1: and a satellite geo stationary orbit will not stay there forever.
Speaker 1: Other gravitational forces from the Sun and the Moon, plus
Speaker 1: the fact that the Earth is not perfectly round, will
Speaker 1: cause the satellites to increase in inclination over time, so
Speaker 1: they'll they'll start to drift a little bit and then
Speaker 1: they will no longer be geo stationary UH satellites. They'll
Speaker 1: have thrusters on them and fuel inside them in order
Speaker 1: to make small corrections, which is called station keeping, and
Speaker 1: that's so that they can stay in the right relative location.
Speaker 1: But once the satellite is used up all its fuel,
Speaker 1: it will experience an increase in inclination. It's unavoidable. You
Speaker 1: can't fix it at that point, and it's possible, depending
Speaker 1: upon how the satellite is located, that it could become
Speaker 1: a hazard to other geo stationary or geosynchronous satellites. So
Speaker 1: normally at the end of a geo stationary satellites useful
Speaker 1: LIFESPAN will send a command to the satellite to say,
Speaker 1: get the heck out of the neighborhood. Boost it at
Speaker 1: a higher altitude, a higher orbit, which moves out of
Speaker 1: the way of other satellites, because it's not gonna be
Speaker 1: useful anyway, so you might as well boost it further
Speaker 1: out and not have it become space junk closer into
Speaker 1: the Earth. There's already a lot of space junk that's
Speaker 1: out there. Fortunately, space is really big. So while there's
Speaker 1: always a threat of space junk being a problem with satellites,
Speaker 1: it's such a huge space that the odds on any
Speaker 1: given day are fairly low of an incident. But the
Speaker 1: more stuff we send up there, the better the odds
Speaker 1: are that something bad will happen. Now, not all orbits
Speaker 1: are in an east west orientation. You're probably imagining that
Speaker 1: these satellites are orbiting the Earth more or less in
Speaker 1: the same direct shouldn't that the Earth rotates, that they
Speaker 1: are going around and around, uh, the same axis of rotation.
Speaker 1: Not all of them do. Some of them are rotating
Speaker 1: north south, they're going around the poles. You have polar orbits,
Speaker 1: which are really good for photography and mapping because as
Speaker 1: these satellites move north to south or south and north,
Speaker 1: depending upon which way you're going, um, the Earth is
Speaker 1: rotating under the satellites, so they get a really good
Speaker 1: view of the Earth. They're great if you want to
Speaker 1: have a satellite map of a region. They're also not
Speaker 1: bad if you're hoping for satellite to pass over a
Speaker 1: certain region on the Earth so you can get a
Speaker 1: better look. In other words, these are used for spying,
Speaker 1: and one particular type of orbit, very specific type of
Speaker 1: orbit is the mulnia or lightning orbit, and the orbit
Speaker 1: takes its name from Soviet satellites that use this particular
Speaker 1: style of orbit or communications networks. It's an elliptical shape,
Speaker 1: which means the satellite spends a lot of its time
Speaker 1: near the apoge poet point the of the orbit, because
Speaker 1: that's where it moves the slowest. So if you plan
Speaker 1: out the telemetry of your satellite in such a way
Speaker 1: so that the apoge is over a specific region, you
Speaker 1: know that when the satellite orbits the Earth, it's gonna
Speaker 1: be spending the majority of its orbit over where the
Speaker 1: apogee is. So if you locate it in a place
Speaker 1: that you're interested in, you're gonna get more coverage of
Speaker 1: that region throughout the duration of the orbit of the satellite.
Speaker 1: So the Soviets planned the apoge to be over the
Speaker 1: northern hemisphere so that they could serve as a communications
Speaker 1: network and maybe also you know, spy on Europe a
Speaker 1: little bit. Perhaps one thing we use satellites for is
Speaker 1: to spread a signal from one location to another, and
Speaker 1: this is a pretty simple idea. Actually, it's just bouncing
Speaker 1: a signal off of a satellite. It's amost like the
Speaker 1: satellite acts as a mirror, although it's also an amplifier.
Speaker 1: So we use an antenna on the Earth pointed up
Speaker 1: towards the satellite we're interested in, and we beam a
Speaker 1: signal into space. It might be audio, it might be video,
Speaker 1: it could be anything really, and that antenna is the
Speaker 1: up link. Now the satellite receives this. They have it
Speaker 1: has its own antenna and receives the signal and then
Speaker 1: runs it through an amplifier and the beams the amplified
Speaker 1: signal back down to the Earth. And on Earth we
Speaker 1: have other antenna known as the down links, that receive
Speaker 1: the incoming signal from the satellite. And using this model,
Speaker 1: we can beam all sorts of useful stuff like communication signals.
Speaker 1: Television studios would send feeds up to satellites, which then
Speaker 1: act as a distribution system. So you would have a
Speaker 1: centralized location where you would have the the video feed,
Speaker 1: video and audio feed. You would send that through an
Speaker 1: up link to a satellite. It would receive it and
Speaker 1: beam it back down to receiving stations. And that was
Speaker 1: how you know, that's how we get television broadcast beyond
Speaker 1: just over the air broadcast. In fact, if you have
Speaker 1: a cable company, you could receive these signals yourself using satellites. Right,
Speaker 1: you could have part of the satellite TV system and
Speaker 1: you have your own little satellite that's pointed up and
Speaker 1: you receive your television signals that way. Or you could
Speaker 1: end up having cable but cable companies also use this method.
Speaker 1: You would have a centralized location that beams a signal up,
Speaker 1: it comes down so that various cable distribution networks received
Speaker 1: the signal and then they send that through the actual
Speaker 1: cables that eventually terminate at your television. So this is
Speaker 1: a very important way of using satellites. Now, I want
Speaker 1: to conclude this episode with a quick discussion about how
Speaker 1: relativity affects satellites, both special and general relativity. Now, these,
Speaker 1: of course are the the theories proposed by Einstein that
Speaker 1: ultimately proved true at least in the case of time dilation,
Speaker 1: because we see it in practice with satellites. One of
Speaker 1: the things we use satellites for is GPS, the Global
Speaker 1: Position System. So GPS positioning system, I should say, and
Speaker 1: GPS is incredibly useful. That's what lets us use real
Speaker 1: time maps on our phones and GPS devices to go
Speaker 1: from point A to point B. But in order for
Speaker 1: GPS to work, it needs to be able to measure
Speaker 1: time very accurately, both for the person who's on Earth
Speaker 1: and the satellite that is providing the very satellites I
Speaker 1: should say that are providing the information that allows us
Speaker 1: to UH to triangulate where we are on the service
Speaker 1: of Earth. So here's the problem. Time dilation. Einstein's theory
Speaker 1: gives us some uh some issues with time. Special relativity
Speaker 1: tells us that the faster we move relative to an
Speaker 1: independent observer, the slower time seems to pass for ourselves.
Speaker 1: Um again, based upon the relative observer to us, time
Speaker 1: will pass exactly the same way. No matter how fast
Speaker 1: we're going we will it will feel the same. So
Speaker 1: if you get on a spaceship that's going near the
Speaker 1: speed of light and you look at your watch, the
Speaker 1: second hand is going to take away as if you
Speaker 1: were on Earth. But to an independent observer, it would
Speaker 1: look like that second hand is going super slow, and
Speaker 1: it would mean that when you finished your journey and
Speaker 1: came back to Earth, more time would appear to have
Speaker 1: passed on Earth than it did for you, even though
Speaker 1: for people on Earth, time was passing normally. For you
Speaker 1: on the spaceship, time was passing normally. It's really only
Speaker 1: when you have this point of reference that you realize
Speaker 1: that you've experienced different amounts of time. Uh, it's kind
Speaker 1: of a mind bender. Well, special relativity tells us that
Speaker 1: these clocks on board the satellites will take a little
Speaker 1: more slowly because they're moving so fast out in space.
Speaker 1: They should actually fall behind the clocks here on Earth
Speaker 1: by about seven micro seconds per day, which doesn't sound
Speaker 1: like a lot, but if you're talking about very precise
Speaker 1: measurements to give you an idea of where you are
Speaker 1: before long, that becomes an insurmountable problem. So seven micro
Speaker 1: seconds per day slower on the satellites compared to the
Speaker 1: clocks on Earth. If that were all there were to it,
Speaker 1: then we would just say, well, we have to find
Speaker 1: a way, like a program that will build in this
Speaker 1: error so that we know ahead of time how to
Speaker 1: adjust for it. But it gets more complicated than that.
Speaker 1: So that's special relativity. But general relativity also plays a part.
Speaker 1: So one of the predictions made by general relativity is
Speaker 1: that clocks closer to a massive object will seem to
Speaker 1: take more slowly than those that are further away from
Speaker 1: a massive object. So if we look at it that way,
Speaker 1: these satellites are very far away from the surface of
Speaker 1: the Earth, so the clocks on the surface of the
Speaker 1: Earth are much closer to a massive object. The clocks
Speaker 1: on the satellites are much further away from a massive object,
Speaker 1: and it's enough to make a big difference. It also
Speaker 1: means that the clocks on the satellites appear to be
Speaker 1: taking faster than the clocks on the ground. So if
Speaker 1: you calculate a prediction using general relativity as your basis
Speaker 1: for how fast those clocks will be ticking on the satellites,
Speaker 1: you would see that they be ahead of our ground
Speaker 1: clocks by about forty five micro seconds per day. Now,
Speaker 1: this actually means that you have to take the difference
Speaker 1: between the forty five seconds in advance and the our
Speaker 1: forty five micro seconds I'm sorry, forty five micro seconds
Speaker 1: in advance from general relativity, and you have to act
Speaker 1: the seven micro seconds behind from special relativity. And it
Speaker 1: tells you that the clocks on board the satellites should
Speaker 1: take a little bit faster than the clocks here on
Speaker 1: the ground. By the tune of thirty eight microseconds per day.
Speaker 1: You take those forty microseconds ahead general relativity, subtract the
Speaker 1: seven microseconds from behind from special relativity, and you get
Speaker 1: thirty eight microseconds ahead uh net. So it again is
Speaker 1: enough for it to cause a high precision system like
Speaker 1: GPS two have errors after just a few days, so
Speaker 1: you have to correct for that. You actually have to
Speaker 1: create a navigational fix so that the system is accurate. Uh.
Speaker 1: Otherwise you would get errors in where the map would
Speaker 1: say you were. You would look at the map and
Speaker 1: as time would go by, these errors would get worse
Speaker 1: and worse, to the point where it would show you
Speaker 1: locations that are just ridiculous, you blocks away from where
Speaker 1: you actually were, and uh and more if time went
Speaker 1: on long enough. In the GPS satellite system was limited,
Speaker 1: so you're talking about you know, errors of around ten
Speaker 1: kilometers every day. That's that's a big deal. You know,
Speaker 1: you're trying to get from point A to point B
Speaker 1: and you're getting errors that are ten kilometers off. That
Speaker 1: could be disastrous. So it would actually be useless after
Speaker 1: a very few days. That's why you have to have
Speaker 1: algorithms built in that take these relativistic effects into account
Speaker 1: so that the results you get on your GPS device
Speaker 1: remain accurate. So I think that's pretty cool that you know,
Speaker 1: satellites are a practical way for us to see how
Speaker 1: relativity can affect us, and that relativity is in fact real.
Speaker 1: It's it's it's not it's not quote unquote just a theory.
Speaker 1: It's something that we can observe directly and though and
Speaker 1: know that this is at play. So I wanted to
Speaker 1: mention that because you know, it's it's pretty cool stuff.
Speaker 1: And honestly, when I was first looking into it years ago,
Speaker 1: when I was looking at how GPS works, I had
Speaker 1: a handle on special relativity. I understood that the speed
Speaker 1: of the movement of the satellites would affect how time
Speaker 1: passes compared to what we see here on Earth on
Speaker 1: the surface, but I was not aware of the effects
Speaker 1: of general relativity. That was something I had to learn
Speaker 1: when I looked up GPS back in the day, which
Speaker 1: I think was a Tuesday, if I'm not mistaken, so
Speaker 1: relatively obviously a very fascinating subject. I would love to
Speaker 1: go into further detail, but I think that's more of
Speaker 1: a stuff to blow your mind than a tech stuff topic.
Speaker 1: We have, of course touched upon RelA ativity a few
Speaker 1: times in our conversations about various types of technology. But
Speaker 1: maybe one day I'll get some stuff to blow your
Speaker 1: mind folks in here, and then we'll have a big
Speaker 1: discussion about relativity, not just what it is, but how
Speaker 1: it directly affects some of the things we do. All right,
Speaker 1: So that wraps up this discussion about satellites, and I
Speaker 1: may do a future episode where I go into board
Speaker 1: detail about the different types of satellites, the instrumentation that
Speaker 1: is aboard these satellites, how they work, who owns them,
Speaker 1: maybe some interesting stories about notable discoveries that satellites have
Speaker 1: made and notable incidents that have happened because of satellites.
Speaker 1: I hope you enjoyed that classic episode of tech stuff
Speaker 1: on how satellites work. I know I've talked about satellites
Speaker 1: and how they work several times since then. I often
Speaker 1: do kind of a truncated abbreviated version, if you will.
Speaker 1: When I have to talk about stuff like Starlink, for example,
Speaker 1: which is space x is uh satellite based internet service
Speaker 1: provider and similar things, you know, I have to talk
Speaker 1: about how the satellites get into orbit, how they maintain orbit,
Speaker 1: what the different orbits mean, how satellites are able to
Speaker 1: keep track of things like making sure that you know
Speaker 1: when you're using a GPS device that you're getting accurate
Speaker 1: information instead of something that's telling you you're in a
Speaker 1: totally different time zone. All this is incredible technology. It's
Speaker 1: really amazing stuff, and it's based off amazing ingenuity, and
Speaker 1: I'll constantly be going back and talking about it. But
Speaker 1: this is sort of the basic information about how satellites work.
Speaker 1: So I hope you enjoyed that. If you have suggestions
Speaker 1: for topics I should cover in future episodes of tech Stuff,
Speaker 1: please reach out to me. One way to do that
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Speaker 1: a guest. I'm always eager to see what you have
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