Speaker 1: Get in tech with Technology with tech Stuff from Stuff
Speaker 1: stateolland Hey there, and welcome to Tech Stuff. I'm Jonathan Strickland,
Speaker 1: your lovable host, and today we're gonna do an episode.
Speaker 1: That was a request from Matthew Aisles who wrote to
Speaker 1: me on Twitter. He actually requested at two part episode
Speaker 1: about satellites. Uh, and I think it's a great idea.
Speaker 1: I don't know if I'll do a second part right away,
Speaker 1: but this first part is going to be a bit
Speaker 1: about the history of satellites, how they work in general,
Speaker 1: and also some cool information about them, like how relativity
Speaker 1: comes into play. I guess it's relatively cool. Whacketty smacketty do. Alright,
Speaker 1: So let's talk about satellites and what they are. So
Speaker 1: satellite is something that's in orbit around another object. And
Speaker 1: of course Earth has had a satellite for billy 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 the foundation for man made satellites, the principles, the
Speaker 1: idea of what would be required, go back well before
Speaker 1: the space race ever started. That would be Isaac Newton
Speaker 1: who came up with the idea of what would be
Speaker 1: required to create a satellite. Now that's not what he
Speaker 1: necessarily called it, but this was published in a famous
Speaker 1: thought experiment back in seventeen twenty nine, and at the
Speaker 1: time he was really concentrating on gravity, which is pretty
Speaker 1: heavy stuff. So Newton's thought experiment was famous. People have
Speaker 1: talked about this a lot. You've probably heard about it.
Speaker 1: He said, what if you were to go at the
Speaker 1: top of a really really tall mountain, and you build
Speaker 1: a cannon on the top of that mountain, and you
Speaker 1: aim that cannon so that the barrel is parallel with
Speaker 1: the Earth below you, so it's at at the same
Speaker 1: you know, same uh angle as the ground down at
Speaker 1: the base of the mountain. You fire the cannon. The
Speaker 1: cannonball flies out and it moves away from the cannon,
Speaker 1: but it also starts to fall because gravity has been
Speaker 1: pulling on the cannonball the whole time. You know, the
Speaker 1: gravity was pulling on the cannonball when it was in
Speaker 1: the cannon. It's pulling on the cannonball now that it's
Speaker 1: emerged from the cannon. Eventually, this cannonball is going to
Speaker 1: fall to the ground. And by eventually it's it's based
Speaker 1: upon the altitude that the cannonball already is at. Uh.
Speaker 1: Doesn't have anything to do with the forward velocity so
Speaker 1: much as the altitude. He said, Well, what if you
Speaker 1: were to to pack more gunpowder in this cannon and
Speaker 1: you fire it, might it will go further because it's
Speaker 1: moving at a forward velocity that's that's greater than the
Speaker 1: previous one. But 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 afford velocity at a at
Speaker 1: a rate that is equal to how the Earth is
Speaker 1: curving away from the cannonball. So, in other words, the
Speaker 1: cannonballs falling toward the Earth, but the Earth is curving
Speaker 1: away from the cannonball at that same rate, So the
Speaker 1: cannonball never falls down to hit the Earth's surface because
Speaker 1: the Earth is falling away from the cannonball at the
Speaker 1: same rate that the cannonball itself is falling. This would
Speaker 1: 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 fifty seven,
Speaker 1: and that's when the then Soviet Union made history by
Speaker 1: launching the first man made satellite into Earth orbit, and
Speaker 1: that satellite was the spot Nick one. But it was
Speaker 1: fairly simple. It was a ball 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 center from the bear 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 barometric switch were in there. So and it
Speaker 1: 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 systems,
Speaker 1: like how hot was it? Or cold was it? What
Speaker 1: was the pressure like? And then it would beam down
Speaker 1: information in a series of beeps. In fact, my former
Speaker 1: co host Chris Palette used to refer to Sputnik as
Speaker 1: the thing what beats. It actually sounded a bit like
Speaker 1: this so if you had had a ham radio back
Speaker 1: in n and you were tuning in, you could actually
Speaker 1: pick up that signal as sput Nick passed overhead, because
Speaker 1: it was broadcasting on a frequency that was within the
Speaker 1: citizen band radio frequency, and that meant that people could
Speaker 1: actually listen in as sput Nick went overhead. It only
Speaker 1: took ninety eight minutes for the satellite to go around
Speaker 1: the Earth, so every hour and a half or so
Speaker 1: you would be able to pick this up. And it
Speaker 1: freaked people out, particularly in the United States. People were
Speaker 1: freaking out because they were able to actually hear evidence
Speaker 1: of the Soviet Union's ability to send an object into space,
Speaker 1: and if they could do that, there was also the
Speaker 1: fear that they could perhaps fire a ballistic missile, maybe
Speaker 1: with a nuclear warhead at the United States that they
Speaker 1: had had now had the capability to fire massive destructive
Speaker 1: weapons at the US from a world away, and at
Speaker 1: this time the Cold War was going on strong, so
Speaker 1: it caused more than a little stir. It was the
Speaker 1: fuel for tons of different science fiction films. Uh they're
Speaker 1: all these different um uh 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 Sputnik itself, you actually have to go back much
Speaker 1: further back to the nineteen forties in fact, or even earlier,
Speaker 1: when you're looking at the the rocket program out of
Speaker 1: the Soviet Union during World War Two. So officially you
Speaker 1: would argue that nineteen fifty two was was what got
Speaker 1: Sputnik itself going. Within the Soviet Union, that's when an
Speaker 1: organization called the International Council of Scientific Unions called for
Speaker 1: artificial satellites to be launched in order to study solar activity,
Speaker 1: which was going to be reaching a peak in nineteen
Speaker 1: fifty eight, and the United States started planning a launch
Speaker 1: at least as far back as nineteen fifty five, and
Speaker 1: their project was called Vanguard, and pretty much the world
Speaker 1: was looking at the United States as the leader it
Speaker 1: was going to be the US that would be launching
Speaker 1: a UH satellite sometime around the summer of nineteen fifty seven.
Speaker 1: But the Soviet Union thought, hey, we have the opportunity
Speaker 1: to show up our rival, and so they really put
Speaker 1: Sputnik on the fast track. Now to to look at
Speaker 1: what was going on in the Soviet Union going back
Speaker 1: to the nineteen thirties and nineteen forties, there was a
Speaker 1: man named Mikhail ticknor Revov. I'm gonna mess up that
Speaker 1: name all the time. Tick Hanravov who led a team
Speaker 1: of scientists to design, build, and launch spot Nik one.
Speaker 1: But their early work was really looking at missile systems,
Speaker 1: ballistic missile missile systems for military use. UH. They just
Speaker 1: saw the potential for using those same systems to launch
Speaker 1: satellite into space. And they were really looking at the
Speaker 1: possibility of using multi stage rockets in order to get
Speaker 1: the right amount of acceleration to push an object into orbit.
Speaker 1: And they were often relying on research performed not just
Speaker 1: by their team, but by other scientific teams around the world.
Speaker 1: Often this was information that we're that was pulled in
Speaker 1: through espionage. It wasn't necessarily the scientific community openly sharing
Speaker 1: this information. And originally UH they were really looking at
Speaker 1: how can we make missiles better missiles for the Soviet Union.
Speaker 1: The group would form in nineteen forty six, so not
Speaker 1: long after the end of World War Two, and the
Speaker 1: team worked on satellite plans pretty much in secret because
Speaker 1: they weren't sure if the Soviet government would actually appreciate
Speaker 1: their interest in scientific research that did not have an
Speaker 1: immediate military application. Now keep in mind that until nineteen
Speaker 1: fifty three, the Soviet Union was being led by Joseph Stalin,
Speaker 1: and he was an incredibly brutal dictator, and paranoia was
Speaker 1: rampant in the Soviet Union. There were stories about secret
Speaker 1: police and kidnappings in the middle of the night. People
Speaker 1: lived in constant fear of being arrested or executed. But
Speaker 1: after Stalin died in March nineteen fifty three, people were
Speaker 1: able to concentrate on something beyond just not being noticed.
Speaker 1: It's hard to imagine how terrifying that time must have been,
Speaker 1: but it's probably no coincidence that it was nineteen fifty
Speaker 1: four when the Soviet scientists stopped hiding the fact that
Speaker 1: they were performing this satellite research. They would talk about
Speaker 1: it openly, and the project received support from various scientific
Speaker 1: societies within the USSR, but it wouldn't be until nineteen
Speaker 1: fifty six that they received official approval from the Kremlin.
Speaker 1: So if you want to hear a really amazing story
Speaker 1: about bureaucracy, science, politics, and how messed up everything was
Speaker 1: in the Soviet Union in the nineteen fifties, you should
Speaker 1: really research the full story of spot Nik, because it's
Speaker 1: amazing that this project ever really got a lot of
Speaker 1: of support. In large part the support was coming from
Speaker 1: the Soviet Union wanting to demonstrate its power, not to
Speaker 1: pursue science, but in order to show the rest of
Speaker 1: the world where the Big Bear don't mess with us.
Speaker 1: There were a whole bunch of different departments that all
Speaker 1: worked on the design of the spot Nick project, and
Speaker 1: it's kind of interesting to see how diverse this group was.
Speaker 1: So those those different departments included the Academy of Sciences
Speaker 1: of USSR, which oversaw the scientific research and development of
Speaker 1: the project. There was the organization Okay b DASH one,
Speaker 1: which was the U s s R Experimental Design Bureau.
Speaker 1: It's essentially was the equivalent of our DARPA here in
Speaker 1: the United States. It was a research and development program
Speaker 1: that really took big risks to see if they could
Speaker 1: find big reward from scientific research implemented in practical ways.
Speaker 1: That particularly, that particular department fell under the direction of
Speaker 1: the Ministry of Defense Industry, so that group was responsible
Speaker 1: for designing the body of the satellite, and in the
Speaker 1: satellite biz we refer to this as the bus. The
Speaker 1: bus is essentially the the body or shell inside which
Speaker 1: all the instrumentation exists, apart from you know, some instrumentation
Speaker 1: obviously has to be on the outside of the bus,
Speaker 1: like any sort of imagery or antenna, but you get
Speaker 1: what I mean. Next, we have the Ministry of Radio Industry.
Speaker 1: They were in charge of flight control systems, radio and
Speaker 1: telemetry systems. Then you had the Ministry of ship Building.
Speaker 1: The ship Building Ministry was responsible for designing the gyroscopes
Speaker 1: that would go in the satellite. You had the Ministry
Speaker 1: of Machine Building. They were responsible for a ground processing, transport, fueling,
Speaker 1: and launch hardware. You had the Ministry of Defense itself,
Speaker 1: which was in charge of launch operations. You had the
Speaker 1: Ministry of Avia Aviation Industry which was in charge of
Speaker 1: the tracking systems, and the Special Committee of the Soviet
Speaker 1: of Ministers, which were all about the management and coordination
Speaker 1: of the program overall. Now, originally spot Nick was referred
Speaker 1: to as Object D and it was supposed to be
Speaker 1: a much larger, much more sophisticated satellite. It was not
Speaker 1: supposed to just be the thing what beeps. It was
Speaker 1: supposed to have a lot of instrumentation for actual scientific
Speaker 1: study with a collection of useful instruments. But the projects
Speaker 1: suffered several setbacks in the design process that kept pushing
Speaker 1: back when they would be able to launch, and there
Speaker 1: was a growing concern that the United States was going
Speaker 1: to be able to launch a satellite in orbit starting
Speaker 1: on July first, nine seven. So they had a new goal.
Speaker 1: They wanted to strip down their ideas to just the
Speaker 1: most essential elements to try and beat America to the punch,
Speaker 1: and they did. They were able to create a much smaller,
Speaker 1: more basic satellite, and they were able to launch it
Speaker 1: before the United States could send their own satellite into space,
Speaker 1: and they set a precedent, and in fact only did
Speaker 1: the USSR beat the USA, they did it twice. The
Speaker 1: second satellite, which was spot Nick two, contained the first
Speaker 1: life form sent into Earth orbit, and that was the
Speaker 1: dog named Lyca and Lica was always destined to die
Speaker 1: during this mission. There was no plan for Lyca to
Speaker 1: return to Earth safely. Uhlica was going to die inside
Speaker 1: the satellite, either by starvation or thirst. It was just
Speaker 1: no or suffocation. That was just known that this was
Speaker 1: a one way trip for the dog. Um the dog
Speaker 1: likely died due to overheating fairly early in the mission,
Speaker 1: based upon what the instrumentation was saying. And there have
Speaker 1: been a lot of web comics, card tunes, and an
Speaker 1: amazing song, more than one song, but there's a great
Speaker 1: song called Space Doggedy which was written by Jonathan Colton
Speaker 1: and obviously has uh a lot of influence from Space
Speaker 1: Oddity from David Bowie Space Oddity in there. Space Doggedy,
Speaker 1: great song. There's actually a video on YouTube someone's put
Speaker 1: together with actual footage of like a from spot Nick two.
Speaker 1: And that's all I'm going to say about that, because
Speaker 1: 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 Likeca 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: that they had planned to launch, but that now felt
Speaker 1: that it was no longer a strong enough offering. They
Speaker 1: needed to come up with a better satellite to really
Speaker 1: be a good response to the Soviet Union's project. So
Speaker 1: the new USA project was called Explorer, and it was
Speaker 1: led by a rocket scientist named Werner von Brown. Von
Speaker 1: Brown was a brilliant physicist, a very intelligent rocket 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 Himler.
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 undeniable, 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 is used to charge
Speaker 1: batteries for power. Some of them actually use fuel cells
Speaker 1: rather than batteries to generate electricity. And we've used nuclear
Speaker 1: power 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 orbits,
Speaker 1: which are very regular and uh and predictable, but some
Speaker 1: have elliptical orbits. And elliptical orbits are interesting because a
Speaker 1: satellite will travel at different speeds along its orbital path.
Speaker 1: So there are two points along that path that we
Speaker 1: call the foci of the elliptical orbit. The point that's
Speaker 1: closest to the planet is the peerage, and that's the
Speaker 1: point at which the satellite will be moving fastest through
Speaker 1: its orbit. It's like think of it like the sling
Speaker 1: shot effect. The furthest point from a planet. The furthest
Speaker 1: point in the orbit of the satellites orbit from a
Speaker 1: planet is the apogee, and that's where the satellite will
Speaker 1: move the slowest in its orbital path. Now, launching a
Speaker 1: satellite into orbit obviously requires rockets and in a rocket launch,
Speaker 1: a special system is used called the inertial guidance system,
Speaker 1: which calculates the adjustments needed to push a satellite into
Speaker 1: the correct orbit. Talk about the different orbits in a second. Typically,
Speaker 1: rockets are fired so that they head eastward, and that
Speaker 1: means that the Earth's rotation gives those rockets a speed boost.
Speaker 1: It's like the rockets are actually flying faster than they
Speaker 1: really are because of the relative motion of the Earth.
Speaker 1: If you were to launch your rocket at the equator,
Speaker 1: you would get the biggest boost because the Earth bulgeon
Speaker 1: is out there. It's the largest diameter. So here's how
Speaker 1: you would determine the boost you get to your speed.
Speaker 1: You take the Earth's circumference, which is about four thousand,
Speaker 1: nine hundred miles or forty thousand, sixty kilometers. You figure
Speaker 1: out how fast the Earth rotates, which is one full
Speaker 1: rotation in approximately twenty four hours, which gives us a
Speaker 1: speed of around one thousand, thirty eight miles per hour
Speaker 1: or one thousand, six hundred sixty nine kilometers per hour.
Speaker 1: That's the rotational speed of the Earth. That's typically that's
Speaker 1: actually at the equator. If you were to look at
Speaker 1: a launch facility at Cape canaveral. The rotational speed is
Speaker 1: different because you're further north of the equator. You're not
Speaker 1: at the thickest part of the Earth. Therefore, the circumference
Speaker 1: is smaller and you have a slower speed, so a
Speaker 1: slower rotational speed at that point, so it's closer to
Speaker 1: around eight miles per hour or one thousand, four hundred
Speaker 1: forty kilometers per hour. But that speed boost gives us
Speaker 1: a big help. So to get the satellite into orbit,
Speaker 1: you have to be going wicked fast, but not as
Speaker 1: fast as what you would need to actually escape Earth's gravity.
Speaker 1: So if you wanted to go out into space and
Speaker 1: beyond Earth's gravity, you're leaving Earth orbit, you're heading out
Speaker 1: to Mars or something. You would have to accelerate to
Speaker 1: at least twenty five thousand, thirty nine miles per hour
Speaker 1: or forty kilometers per hour to escape Earth's gravity and
Speaker 1: enter outer space. Putting a satellite in orbit requires less speed,
Speaker 1: and it all depends upon which orbit you're trying to
Speaker 1: insert the satellite into. The orbits determine the speed, so
Speaker 1: lower orbits require faster speeds, which might seem counterintuitive at first,
Speaker 1: but you gotta remember those lower orbits that that speed
Speaker 1: is meant to counteract the gravitational pull of Earth so
Speaker 1: that the object in orbit remains in orbit, doesn't get
Speaker 1: pulled back down to the ground. So when you're closer
Speaker 1: to Earth, the force of gravity is greater. As you
Speaker 1: probably remember, gravity is dependent upon two things, the mass
Speaker 1: of two objects and their relative distance to one another.
Speaker 1: So as distance increases gravitation gravitational pull decreases, and you
Speaker 1: don't need to counteract that with more velocity to make
Speaker 1: sure an object stays within its orbital path and doesn't
Speaker 1: deteriorate and fall into the Earth. So higher orbits require
Speaker 1: lower speeds, and if you get far enough out there,
Speaker 1: you can have a satellite that orbits at the same
Speaker 1: speed as Earth's rotation. Uh those would be geostationary orbits.
Speaker 1: They would appear to be directly above a fixed point
Speaker 1: on the Earth and they would not move from that point.
Speaker 1: I'll get into that more in it just a second. First,
Speaker 1: let's talk about the various types of orbits from an altitude,
Speaker 1: because we can describe orbits in different ways. You can
Speaker 1: describe their orbital pathway, whether it's circular or elliptical, you
Speaker 1: can describe it in its altitude, and you can describe
Speaker 1: it in its orientation as in, is it equatorial, is
Speaker 1: it directly above the equator? Is there any degree of inclination? Uh?
Speaker 1: Is it a polar orbit which goes north south not
Speaker 1: east west? Lots of different ways to describe them. So
Speaker 1: from an altitude perspective, we start with lower thorbit. That's
Speaker 1: the one closest end to the Earth, and that's an
Speaker 1: arrange that's between a hundred eleven miles and one thousand,
Speaker 1: two hundred forty three miles above the surface of the Earth.
Speaker 1: In kilometers that would be a hundred eighty to two
Speaker 1: thousand uh. This tends to be the altitude we use
Speaker 1: for satellites that collect surface observations, photography, weather satellites, that
Speaker 1: kind of thing. When you go further out, you get
Speaker 1: to medium Earth orbit that's in a zone that's between
Speaker 1: one thousand, two hundred forty three miles and twenty two thousand,
Speaker 1: two hundred twenty three miles or in kilometers way easier
Speaker 1: two thousand to thirty six thousand kilometers. Navigation satellites like
Speaker 1: GPS tend to be at this altitude, although summer at
Speaker 1: higher altitudes. Then you get to geosynchronous orbit. That's when
Speaker 1: you are at an altitude that's greater than twenty two
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 is a
Speaker 1: subset of geosynchronous satellites called geo stationary satellites, So all
Speaker 1: geostationary satellites are also geosynchronous, but not all geosynchronous satellites
Speaker 1: are geo stationary. If you have a geostationary satellite, that's
Speaker 1: one of those satellites that remains over a fixed position
Speaker 1: on the Earth's sir So you could build an antenna
Speaker 1: at that point pointed straight up into the atmosphere and
Speaker 1: it's going to be aimed directly at that satellite, and
Speaker 1: as long as nothing changes in that satellite's orbit. Things
Speaker 1: do change over time, so you have to correct it occasionally,
Speaker 1: but as long as nothing changes, UH, the antenna and
Speaker 1: satellite will always be in alignment. That's a geostationary satellite. UH.
Speaker 1: It doesn't matter if it's day or night. You're always
Speaker 1: going to have a direct line of sight between the
Speaker 1: antenna and the satellite, and the satellite is gonna be
Speaker 1: too far away from you to see it, but there's
Speaker 1: a direct line of site as far as the antenna
Speaker 1: is concerned. All geostationary satellites are geosynchronous, like I said,
Speaker 1: But if the opposite isn't true, what's going on? How
Speaker 1: are geo secret as satellites that aren't geo stationary? 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: If the satellite has any inclination or a non circular
Speaker 1: orbital path, it will not be geo stationary. The satellite
Speaker 1: will appear to roam over the Earth's surface, so in
Speaker 1: elliptical orbits, those egg shaped orbits, the satellite would be
Speaker 1: moving at different speeds along its journey. Remember the paragean apogee.
Speaker 1: It's going to be moving at at different velocities as
Speaker 1: it goes around the Earth. Inclination, by the way, is
Speaker 1: the angle between a reference plane and the orbital plane.
Speaker 1: The reference plane in this case, UH, we're talking specifically
Speaker 1: about the equator. So imagine you've got the Earth's globe,
Speaker 1: You've got it tilted at a slight angle because the
Speaker 1: axis is on an angle, and you've got the equator.
Speaker 1: If you have a geosynchronous satellite directly above the equator,
Speaker 1: it's going to be geo stationary. It's gonna stay around
Speaker 1: that fixed point. But if you go north or south
Speaker 1: of the equator and you place a satellite there, it
Speaker 1: will it will not stay above a fixed point. Its
Speaker 1: orbit is going to be slightly angled. That's the inclination
Speaker 1: we would talk about. UH. So as it would go
Speaker 1: around the pathway, uh, it would actually roam over the
Speaker 1: surface of the Earth. So a satellite that has degrees
Speaker 1: of inclination and its orbit with respect to the equator
Speaker 1: will move north and south of the equator as it
Speaker 1: completes an orbit. So this satellite is going to stay
Speaker 1: more or less in the same east west area, but
Speaker 1: it's going to go north south as it goes throughout
Speaker 1: its orbit. Satellites with an elliptical path will drift east
Speaker 1: and west from any fixed point on the Earth as
Speaker 1: a satellite moves faster or slower through its Earth orbit.
Speaker 1: We have seen there are several satellites that use this
Speaker 1: where they are both the inclination and an elliptical path,
Speaker 1: so they make this almost like a figure eight kind
Speaker 1: of pattern over a general region of the Earth's surface,
Speaker 1: which could be really useful for things like communication satellites
Speaker 1: or or even GPS in that in that sense, there
Speaker 1: are some GPS satellites that work under this principle. Geo
Speaker 1: stationary satellites have a view of about of the Earth's surface.
Speaker 1: Just a single geo stationary satellite can see about of
Speaker 1: the Earth's surface from where it is. So if you
Speaker 1: just create a network of a few geo stationary satellites,
Speaker 1: you can get a view of practically the entire Earth,
Speaker 1: really everything between eighty one degree south and eighty one
Speaker 1: degrees north. Beyond those those uh those degrees, you wouldn't
Speaker 1: be able to see it just from the way the
Speaker 1: Earth is curved, but you'd get to see everything between
Speaker 1: the two. Geo stationary satellites tend to be used for communications.
Speaker 1: It's great solution for us on the ground because you
Speaker 1: don't need to move the antenna on the surf to
Speaker 1: stay in contact with the satellite. If the satellite we're drifting,
Speaker 1: if it if it orbited the Earth multiple times during
Speaker 1: a rotation, you would constantly have to adjust your antenna
Speaker 1: to remain in contact with the satellite, and there will
Speaker 1: be times where you would be out of contact with
Speaker 1: the satellite. It would have the Earth between you and
Speaker 1: the antenna. So geo stationary makes this easy because it's
Speaker 1: always going to be directly above the antenna. So it
Speaker 1: makes an ideal communication satellite in that respect, But there
Speaker 1: are a limited number of slots for geostationary satellites. You know,
Speaker 1: you could go to different altitudes, but you're going to
Speaker 1: be you're going to be stuck at that equator plane.
Speaker 1: So you don't want satellites to collide with one another.
Speaker 1: Obviously they would destroy or at least damage one or
Speaker 1: both satellites, and you don't want the actual data communication
Speaker 1: to interfere with each other, so you have to separate
Speaker 1: them out by space. You can't have them to pack
Speaker 1: pecked in too closely together, and a satellite geo stationary
Speaker 1: orbit will not stay there forever. Other gravitational forces from
Speaker 1: the Sun and the Moon, plus the fact that the
Speaker 1: Earth is not perfectly round, will cause the satellites to
Speaker 1: increase in inclination over time, so they'll they'll start to
Speaker 1: drift a little bit, and then they will no longer
Speaker 1: be geo stationary UH satellites. They'll have thrusters on them
Speaker 1: and fuel inside them in order to make small corrections,
Speaker 1: which is called station keeping, and that's so that they
Speaker 1: can stay in the right relative location. But once the
Speaker 1: satellite is used up all its fuel, it will experience
Speaker 1: an increase in inclination. It's unavoidable. You can't fix it
Speaker 1: at that point, and it's possible, depending upon how the
Speaker 1: satellite is located, that it could become a hazard to
Speaker 1: other geo stationary or geosynchronous satellites. So normally, at the
Speaker 1: end of a geostationary satellites useful lifespan will send a
Speaker 1: command to the satellite to say, get the heck out
Speaker 1: of the neighborhood. Boost it at a higher altitude, a
Speaker 1: higher orbit, which moves out of the way of other satellites,
Speaker 1: because it's not gonna be useful anyway, so you might
Speaker 1: as well boost it further out and not have it
Speaker 1: become space junk closer into the Earth. There's already a
Speaker 1: lot of space junk that's out there. Fortunately, space is
Speaker 1: really big, so while there's always a threat of space
Speaker 1: junk being a problem with satellites, it's such a huge
Speaker 1: space that the odds on any given day are fairly
Speaker 1: low of an incident. But the more stuff we send
Speaker 1: up there, the better the odds are that something bad
Speaker 1: will happen. Now, not all orbits are in an east
Speaker 1: west orientation. You're probably imagining that these satellites are orbiting
Speaker 1: the Earth more or less in the same direction that
Speaker 1: the Earth rotates, that they are going around and around, uh,
Speaker 1: the same axis of rotation. Not all of them do.
Speaker 1: Some of them are rotating north south. They're going around
Speaker 1: uh the poles, you know, Poller orbits, which are really
Speaker 1: good for photography and mapping because as these satellites move
Speaker 1: north to south or south and north, depending upon which
Speaker 1: way you're going, UM, the Earth is rotating under the satellites,
Speaker 1: so they get a really good view of the Earth.
Speaker 1: They're great if you want to have a satellite map
Speaker 1: of a region. They're also not bad if you're hoping
Speaker 1: for satellite to pass over a certain region on the
Speaker 1: Earth so you can get a better look. In other words,
Speaker 1: these are used for spying. And one particular type of orbit,
Speaker 1: very specific type of orbit, is the mulnia or lightning orbit,
Speaker 1: and the orbit takes its name from Soviet satellites that
Speaker 1: use this particular style of orbit for communications networks. It's
Speaker 1: an elliptical shape, which means the satellite spends a lot
Speaker 1: of its time near the apogee poet point the of
Speaker 1: the orbit, because that's where it moves the slowest. So
Speaker 1: if you plan out the telemetry of your satellite in
Speaker 1: such a way so that the apogee is over a
Speaker 1: specific region, you know that when the satellite orbits the Earth,
Speaker 1: it's gonna be spending the majority of its orbit over
Speaker 1: where the apogee is. So if you locate it in
Speaker 1: a place that you're interested in, you're gonna get more
Speaker 1: coverage of that region throughout the duration of the orbit
Speaker 1: of the satellite. So the Soviets planned the apoge to
Speaker 1: be over the northern hemisphere so that they could serve
Speaker 1: as a communications network and maybe also you know, spy
Speaker 1: on Europe a little bit. Perhaps one thing we use
Speaker 1: satellites for is to spread a signal from one location
Speaker 1: to another. And this is a pretty simple idea. Actually,
Speaker 1: it's just bouncing a signal off of a satellite. It's
Speaker 1: almost like the satellite acts as a mirror, although it's
Speaker 1: also an amplifier. So we use an antenna on the
Speaker 1: Earth pointed up towards the satellite we're interested in, and
Speaker 1: we beam as signal into space. It might be audio,
Speaker 1: it might be video, it could be anything really, and
Speaker 1: that antenna is the up link. Now the satellite receives this.
Speaker 1: They have it has its own antenna and receives the
Speaker 1: signal and then runs it through an amplifier and the
Speaker 1: beams the amplified signal back down to the Earth. And
Speaker 1: on Earth we have other antenna known as the down links,
Speaker 1: that receive the incoming signal from the satellite. And using
Speaker 1: this model, we can beam all sorts of useful stuff
Speaker 1: like communication signals. Television studios would send feeds up to satellites,
Speaker 1: which then act as a distribution system. So you would
Speaker 1: have a centralized location where you would have the the
Speaker 1: video feed, video and audio feed. You would send that
Speaker 1: through an up link to a satellite that would receive
Speaker 1: it and beam it back down to receiving stations, and
Speaker 1: that was how you know, that's how we get television
Speaker 1: broadcast beyond just over the air broadcast. In fact, if
Speaker 1: you have a cable company, you could receive these signals
Speaker 1: yourself using satellites. Right, you could have part of the
Speaker 1: satellite TV system and you have your own little satellite
Speaker 1: that's pointed up and you receive your television signals that way.
Speaker 1: Or you could end up having cable but cable companies
Speaker 1: also use this method. You would have a centralized location
Speaker 1: that beams a signal up, it comes down so that
Speaker 1: various cable distribution networks received the signal and then they
Speaker 1: send that through the actual cables that eventually terminate at
Speaker 1: your television. So this is a very important way of
Speaker 1: using satellites. Now, I want to conclude this episode with
Speaker 1: a quick discussion about how relativity affects satellites, both special
Speaker 1: and general relativity. Now, these, of course, are the the
Speaker 1: theories proposed by Einstein that ultimately proved true at least
Speaker 1: in the case of time dilation, because we see it
Speaker 1: in practice with satellites. One of the things we use
Speaker 1: satellites for is GPS, the Global position system. So GPS
Speaker 1: positioning system, I should say, and GPS is incredibly useful.
Speaker 1: That's what lets us use real time maps on our
Speaker 1: phones and GPS devices to go from point A to
Speaker 1: point B. But in order for GPS to work, it
Speaker 1: needs to be able to measure time very accurately, both
Speaker 1: for the person who's on Earth and the satellite that
Speaker 1: is providing the very satellites I should say that are
Speaker 1: providing the information that allows us to UH to triangulate
Speaker 1: where we are on the service of Earth. So here's
Speaker 1: the problem. Time dilation. Einstein's theory gives us some uh
Speaker 1: some issues with time. Special relativity tells us that the
Speaker 1: faster we move relative to an independent observer, the slower
Speaker 1: time seems to pass for ourselves. Um again, based upon
Speaker 1: the relative observer to us, time will pass exactly the
Speaker 1: same way. No matter how fast we're going we will
Speaker 1: it will feel the same. So if you get on
Speaker 1: a spaceship that's going near the speed of light and
Speaker 1: you look at your watch, the second hand is going
Speaker 1: to take away as if you were on Earth. But
Speaker 1: to an independent observer, it would look like that second
Speaker 1: hand is going super slow, and it would mean that
Speaker 1: when you finished your journey and came back to Earth,
Speaker 1: more time would appear to have passed on Earth than
Speaker 1: it did for you, even though for people on Earth
Speaker 1: time was passing normally, for you on the spaceship time
Speaker 1: was passing normally. It's really only when you have this
Speaker 1: point of reference that you realize that you've experienced different
Speaker 1: amounts of time. Uh, it's kind of a mind bender, right. Well,
Speaker 1: special relativity tells us that these clocks on board the
Speaker 1: satellites will take a little more slowly because they're moving
Speaker 1: so fast out in space. Uh, they should actually fall
Speaker 1: behind the clocks here on Earth by about seven micro
Speaker 1: seconds per day, which doesn't sound like a lot, but
Speaker 1: if you're talking about very precise measurements to give you
Speaker 1: an idea of where you are before long, that becomes
Speaker 1: an insurmountable problem. So seven microseconds per day slower on
Speaker 1: the satellites compared to the clocks on Earth. If that
Speaker 1: were all there were to it, then we would just say, well,
Speaker 1: we have to find a way, like a program that
Speaker 1: will build in this error so that we know ahead
Speaker 1: of time how to adjust for it. But it gets
Speaker 1: more complicated than that. So that's special relativity. But general
Speaker 1: relativity also plays a part. So one of the predictions
Speaker 1: made by general relativity is that clocks closer to a
Speaker 1: massive object will seem to tick more slowly than those
Speaker 1: that are further away from a massive object. So if
Speaker 1: we look at it that way, these satellites are very
Speaker 1: are away from the surface of the Earth, so the
Speaker 1: clocks on the surface of the Earth are much closer
Speaker 1: to a massive object. The clocks on the satellites are
Speaker 1: much further away from a massive object, and it's enough
Speaker 1: to make a big difference. It also means that the
Speaker 1: clocks on the satellites appear to be taking faster than
Speaker 1: the clocks on the ground. So if you calculate a
Speaker 1: prediction using general relativity as your basis for how fast
Speaker 1: those clocks will be ticking on the satellites, you would
Speaker 1: see that they'd be ahead of our ground clocks by
Speaker 1: about forty five micro seconds per day. Now, this actually
Speaker 1: means that you have to take the difference between the
Speaker 1: forty five seconds in advance and the our forty five
Speaker 1: micro seconds I'm sorry, forty five micro seconds in advance
Speaker 1: from general relativity, and you have to subtract the seven
Speaker 1: micro seconds behind from special relativity, and it tells you
Speaker 1: that the clocks on board the satellites should take a
Speaker 1: little bit faster than the clocks here on the ground,
Speaker 1: by the tune of thirty eight my acrow seconds per day.
Speaker 1: You take those forty five microseconds ahead general relativity, subtract
Speaker 1: the seven microseconds from behind from special relativity, and you
Speaker 1: get thirty eight microseconds ahead. Uh net. So it again
Speaker 1: is enough for it to cause a high precision system
Speaker 1: like GPS two have errors after just a few days,
Speaker 1: so you have to correct for that. You actually have
Speaker 1: to 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 on slee When I was first looking into it
Speaker 1: years ago, when I was looking at how GPS works,
Speaker 1: I had a handle on special relativity. I understood that
Speaker 1: the speed of the movement of the satellites would affect
Speaker 1: how time passes compared to what we see here on
Speaker 1: Earth on the surface, but I was not aware of
Speaker 1: the effects of general relativity. That was something I had
Speaker 1: to learn when I looked up GPS back in the day,
Speaker 1: which I think was a Tuesday. If I'm not mistaken
Speaker 1: so relatively obviously a very fascinating subject. I would love
Speaker 1: to go into further detail, but I think that's more
Speaker 1: of a stuff to blow your mind than a tech
Speaker 1: stuff topic. We have, of course touched upon relativity a
Speaker 1: few times in our conversations about various types of technology.
Speaker 1: But maybe one day I'll get some stuff to blow
Speaker 1: your mind folks in here, and then we'll have a
Speaker 1: big discussion about relativity, not just what it is is,
Speaker 1: but how it directly affects some of the things we do. Alright,
Speaker 1: So that wraps up this discussion about satellites, and I
Speaker 1: may do a future episode where I go into more
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: There's a lot of information out there and it's really
Speaker 1: fascinating stuff. So that might end up being a future episode. Heck,
Speaker 1: it might be the next one. I haven't yet scheduled
Speaker 1: what my next episode will be, so keep any year
Speaker 1: out for that. But if you guys have suggestions for
Speaker 1: future episodes. Why don't you do what? What aisles? Did
Speaker 1: you know? It was very helpful sending me a message,
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