ROCKET SCIENCE explained in 15 minutes! And How do satellites work?

Summary

This video, sponsored by Square Space, delves into the fascinating world of rocket science and satellite technology. It explains how communications satellites operate and are launched into geostationary orbits, where they remain fixed relative to the Earth's rotation. The script covers the physics behind orbital mechanics, the role of Kepler's laws and Newton's laws, and the engineering marvels that enable satellites to transmit signals globally. It also touches on the practical aspects of satellite placement, the challenges of space real estate, and the future of satellite technology. Viewers are encouraged to appreciate the complexity behind everyday technologies like GPS and live TV broadcasts.

Takeaways

• 🚀 Rocket science is often considered the epitome of complexity, but this video aims to demystify it by explaining satellite communications.
• 🌐 Communications satellites are integral to our daily lives, impacting activities like GPS navigation, weather updates, and live TV broadcasts.
• 🛰️ There are nearly 3000 operational satellites orbiting Earth, with many more planned, highlighting the importance of satellite technology.
• 🌍 Geostationary satellites, which remain stationary relative to the Earth's rotation, are crucial for continuous communication and broadcasting services.
• 📚 Orbital mechanics, based on Kepler’s laws and Newton’s laws of gravitation, is fundamental to calculating satellite orbits and speeds.
• 🔢 The geostationary orbit is at an altitude of 35,786 km from the equator, with an orbital period that matches the Earth's rotation, minus the time it takes for the Sun to reappear in the same position.
• 🚀 Launching satellites into geostationary orbit requires powerful rockets like the Atlas V, which can carry heavy payloads and provide the necessary speed.
• 🔥 Rocket engines operate on the principle of Newton's third law, where the expulsion of exhaust gases generates the thrust needed to propel the rocket.
• 🛰️ Achieving geostationary orbit involves multiple stages, including launching into an elliptical orbit and then circularizing it at the correct altitude.
• 🌐 The International Telecommunication Union (ITU) strictly regulates the placement of satellites in geostationary orbit to avoid congestion.
• 🔋 Once in orbit, satellites deploy solar panels to power their operations, including receiving, amplifying, and relaying signals back to Earth.

Q & A

What is the significance of rocket science in our daily lives?

Rocket science plays a significant role in our daily lives through communication satellites, which enable services like GPS navigation, weather updates, and live TV broadcasts from foreign countries.

How many operational satellites are orbiting the Earth currently?

There are almost 3000 operational satellites orbiting the Earth, owned by over 100 different countries.

What is a geostationary orbit and why is it important for communication satellites?

A geostationary orbit is a circular orbit 35,786 km from the equator where satellites appear stationary relative to the Earth's rotation. This allows for a fixed position of satellite dishes on the ground, making it ideal for communication satellites.

How do Kepler's laws of planetary motion contribute to the understanding of satellite orbits?

Kepler's laws allow us to calculate the period and speed of satellites in geostationary orbits, which is crucial for determining their positioning and maintaining their orbits.

What is the orbital period of a geostationary satellite and how does it relate to the Earth's rotation?

The orbital period of a geostationary satellite is 23.93 hours, which is slightly less than 24 hours to match the Earth's rotation with respect to a non-rotating frame of reference, known as a sidereal day.

Why do rockets carry their own oxidizer instead of relying on atmospheric oxygen like jet engines?

Rockets carry their own oxidizer because they operate in outer space where there is no atmosphere available, unlike jet engines which require atmospheric oxygen to combust fuel.

What is the role of Newton's third law in rocket propulsion?

Newton's third law, which states that for every action, there is an equal and opposite reaction, is fundamental to rocket propulsion. The expulsion of high-pressure exhaust gases from the rocket engine generates the thrust that propels the rocket forward.

How do modern rockets maintain stable flight without the use of large fins?

Modern rockets maintain stable flight through gimbaled thrust, which involves swiveling the thrust nozzle to keep the rocket stable, instead of relying on large fins which add extra weight and aerodynamic drag.

What is the significance of launching rockets close to the equator and how does it affect their trajectory?

Launching rockets close to the equator is beneficial because it allows the rocket to take advantage of the Earth's rotational speed, reducing the amount of fuel needed to reach orbit and helping to achieve the desired trajectory with less effort.

How are communication satellites adjusted to achieve a geostationary orbit after launch?

After launch, communication satellites are initially in an elliptical orbit. They are adjusted to a geostationary orbit through a series of burns at the apogee of the orbit, which circularize the orbit and raise the perigee to the geostationary altitude.

Why is the geostationary orbit also known as the 'Clarke orbit'?

The geostationary orbit is sometimes called the 'Clarke orbit' after science fiction writer Arthur C. Clarke, who was the first to detail its usefulness in a story he wrote in 1945,预见了这种轨道在未来科学事实中的应用。

Outlines

00:00

🚀 Introduction to Rocket Science and Satellites

The script begins by highlighting the complexity of rocket science, often used as a benchmark for difficulty. It introduces the concept of communication satellites and their significant impact on daily life, such as GPS navigation, weather updates, and live TV broadcasts. The video promises to demystify the science behind how these satellites work and are launched into orbit. The script explains that there are nearly 3000 operational satellites, with about 550 in geostationary orbits, which appear stationary relative to the Earth's rotation. It delves into the basics of orbital mechanics, mentioning Kepler's laws and Newton's laws of universal gravitation, essential for calculating a satellite's orbit. The geostationary orbit's distance from the equator and its period are also discussed, along with the reasons behind the slight discrepancy from a 24-hour period.

05:04

🔧 How Rockets Work and Launch Satellites

This section explains how rockets function, focusing on the principle of Newton's third law, which is crucial for propulsion. It describes the role of rocket engine nozzles in increasing exhaust gas velocity to enhance thrust. The script also covers the importance of fuel pumps in delivering fuel at high pressure and the method of using a small amount of fuel to drive turbines that power these pumps. The discussion then shifts to the stability of rocket flight, contrasting early rocket designs with modern approaches that use gimbaled thrust for stability instead of fins. The process of achieving a geosynchronous orbit is outlined, including the transition from an elliptical to a circular orbit and the precise timing of thruster ignition at the apogee. The script also touches on the limitations of space real estate in geostationary orbits, the challenges of launching from non-equatorial locations, and the benefits of launching close to the equator.

10:08

🌐 Satellite Operations and the Role of ITU

The final paragraph discusses the operational aspects of satellites once they are in orbit. It covers the deployment of solar panels to power the satellite and the satellite's primary function of receiving, amplifying, and relaying radio transmissions back to Earth. The script explains the importance of frequency shifting to prevent signal interference and the challenges of transmitting radio waves over long distances. It also mentions the size limitations of satellite antennas due to space constraints within the rocket. The paragraph introduces the term 'Clarke orbit' for geostationary orbits, named after science fiction writer Arthur C. Clarke, who foresaw their utility. The video concludes with a sponsorship mention for Squarespace, a website builder, and an invitation for viewers to ask questions in the comments section.

Keywords

💡Rocket Science

Rocket Science refers to the field of engineering and physics that deals with the design, construction, and operation of rockets. In the video, it is used to emphasize the complexity of understanding and launching satellites into space. The script mentions, 'Wouldn't it be nice to be able to say something like, "well, I actually know rocket science, and I think this is more difficult than rocket science."' This highlights the video's aim to demystify the perceived difficulty associated with the subject.

💡Communications Satellites

Communications satellites are artificial satellites used for telecommunications, including television, radio, telephone, and internet. The video explains how they work and their impact on daily life, stating 'Although there are several different types of satellites, these types are the ones that probably have the biggest impact in our daily lives.'

💡Geostationary Orbit

A geostationary orbit is a circular orbit 35,786 km above the Earth's equator and at the same rotational speed as the Earth, making satellites appear stationary from the ground. The video explains, 'What this means is that, the satellite appears stationary compared to the rotation of the earth.' This is crucial for satellites providing continuous coverage for services like live TV broadcasts.

💡Orbital Mechanics

Orbital mechanics is the study of the motions of artificial satellites and the forces that affect them. The video connects this concept to the historical context, mentioning 'Orbital mechanics is rooted in Keppler’s laws of planetary motion, published way back in 1609.' It is essential for calculating the paths and speeds of satellites.

💡Newton’s Laws of Universal Gravitation

Newton’s Laws of Universal Gravitation are fundamental to understanding how gravity affects objects in space. The script states, 'Newton’s laws of universal gravitation, published in the Principia Mathematica around 1687 also plays a role in many calculations.' These laws help in calculating the necessary speed and altitude for satellites to maintain their orbits.

💡Atlas V

Atlas V is a type of rocket used to launch satellites into orbit. The video mentions, 'In the United States, one workhorse rocket for this task has been the Atlas V.' It is an example of the technology used to overcome the challenges of space travel and place satellites into geostationary orbit.

💡Rocket Propulsion

Rocket propulsion is the means by which rockets are able to generate thrust and move through space. The video explains, 'A rocket does not rely on the atmosphere to oxidize the fuel like a jet engine does. That’s because it carries its own oxidizer.' This is a key concept in understanding how rockets are able to operate in the vacuum of space.

💡Gimbaled Thrust

Gimbaled thrust refers to the ability of a rocket engine to swivel its thrust nozzle to maintain stability during flight. The script mentions, 'Stability comes from swiveling the thrust nozzle to keep it stable. This is called gimbaled thrust.' This technology is crucial for ensuring that rockets maintain a stable trajectory as they ascend.

💡International Telecommunication Union (ITU)

The ITU is an organization that regulates and assigns slots for satellites in geostationary orbit to prevent congestion and interference. The video states, 'The international telecommunications union (ITU) which assigns each satellite a slot at this perimeter.' This highlights the importance of international cooperation in managing space resources.

💡Geostationary Orbit Real Estate

The term 'Geostationary Orbit Real Estate' refers to the limited and valuable space in geostationary orbit where satellites can be positioned. The video describes, 'The real estate here has is a prized commodity, as you might imagine, and is tightly controlled by an organization called the international telecommunications union (ITU).' This underscores the competitive nature of securing space for satellites in this orbit.

💡Low Earth Orbit (LEO)

Low Earth Orbit refers to an orbit around Earth with an altitude of approximately 2,000 km (1,200 miles) or less. The video contrasts this with geostationary orbit, noting, 'Not all communications satellites are placed in geostationary orbits. Some are placed in low earth orbit too.' LEO satellites require more frequent handoffs of transmissions but are less expensive to launch and operate.

Highlights

Rocket science is often considered synonymous with difficulty.

The video aims to demystify how communications satellites work and are launched into orbit.

Satellites have a significant impact on our daily lives, with nearly 3000 operational satellites orbiting the Earth.

Geostationary satellites appear stationary from the Earth's surface.

Orbital mechanics is based on Kepler’s laws of planetary motion and Newton’s laws of universal gravitation.

The speed and period of a satellite depend only on its radius from the center of the Earth, not its mass.

A geostationary orbit is at an altitude of 35,786 km from the equator.

The orbital period of a geostationary satellite is 23.93 hours, matching the Earth's rotation.

Communications satellites are launched using rockets like the Atlas V, which can carry heavy payloads.

Rockets function based on Newton's third law, with combustion creating thrust.

Modern rockets use gimbaled thrust for stability instead of large fins.

Achieving a geostationary orbit involves several stages, starting with an elliptical orbit.

The International Telecommunication Union (ITU) controls and assigns slots for satellites in geostationary orbit.

Launching rockets near the equator is beneficial due to the Earth's rotational speed and reduced inclination.

Not all communications satellites are in geostationary orbit; some are in low Earth orbit.

Once in orbit, satellites deploy solar panels for power and use antennas to receive and transmit signals.

Geostationary orbit is also known as the 'Clarke orbit', named after science fiction writer Arthur C. Clarke.

The video is sponsored by Squarespace, offering a website builder for creators and entrepreneurs.

Transcripts

This video is sponsored by Square  Space. Stay tuned to the end to

find out about their special  offer for Arvin Ash viewers.

How many times have you heard someone  describe a difficult concept as

“it’s not rocket science” – meaning  it’s not as difficult to understand

as rocket science is. Rocket science  is synonymous with difficult subjects.

Wouldn’t it be nice to be able  to say something like, "well,

I actually know rocket science, and I think  this is more difficult than rocket science."

After watching today’s video, I think  you may very well have the background

to be able to say just that, because I’m going  to show you how communications satellites work,

and how they are launched into orbit.

Although there are several  different types of satellites,

these types are the ones that probably  have the biggest impact in our daily lives.

But to understand what these things  do and how they are launched,

you’re going to have to learn  something about…you got it,

rocket science. And I’m hoping you’ll find that  it’s really not as hard as it’s cracked up to be.

That’s coming up right now…

If you’ve ever used a GPS app to find directions,

or if you have looked up the weather for your  town, or watched a live TV broadcast from a

foreign country – you have interacted with a  satellite. Satellites affect our daily lives.

There are almost 3000 operational satellites,  owned by over 100 different countries, orbiting

the earth right now. And thousands  more are planned for the future.

About 550 of these are in what’s  called geo stationary orbits.

Communications satellites are typically  in such orbits. What this means is that,

the satellite appears stationary compared  to the rotation of the earth. It stays in

the same point in the sky at all times. In  other words, you can leave your satellite

dish that receives your favorite TV shows in  one position, and never have to change it.

So the question is how do scientists calculate  where to put the satellite so that it remains

at the same point in space? Orbital mechanics  is rooted in Keppler’s laws of planetary motion,

published way back in 1609. Newton’s  laws of universal gravitation,

published in the Principia Mathematica around  1687 also plays a role in many calculations.

Keppler’s laws allow us to calculate the  period and speed of such a satellite.

Speed is the square root of mu over r, where mu  is the standard gravitational parameter, equal

to the Newtont’s gravitational  constant times the mass of the planet,

r is the radius of the satellite  from the center of the earth.

And the period has the following  formula. Note that the speed and period

only depends on the radius of the  satellite, and not on its mass.

A geo stationary orbit is circular,

and since the altitude of the satellite does not change, its speed must be constant.

If you do the calculations, you will  find that the geostationary orbit is

35,786 km from the equator. The  orbital period is 23.93 hours,

or 23 hours 56 minutes. You might say,  why isn’t It exactly 24 hours? Well,

23 hours and 56 minutes is actually equal to one  sidereal day. This is the time it actually takes

for the earth to complete one rotation with  respect to a non-rotating frame of reference.

The reason we normally count 24 hours as being one  day, is because 24 hours is the precise time the

sun is at the same spot in the sky every day. But  you have to keep in mind that the earth moves with

respect to the sun. The earth moves 1/365th of the  arc around the sun during this time. That’s about

4 minutes. In other words, the earth has to rotate  just a little bit more about 4 minutes, before the

sun is directly overhead. But one full rotation  around its axis is actually 4 minutes less than that.

Now the question is how is a communications  satellite inserted into such an orbit? The first

step in this process is to launch the satellite  on a rocket that has the payload capacity to carry

the satellite to this orbit, and can impart  the speed necessary to maintain this orbit.

In the United States, one workhorse  rocket for this task has been the Atlas V.

This rocket weighs about 700,000 lbs, or 317,000  kilograms at launch and can lift 28,000 lbs,

or 12,700 kilograms to geostationary orbit. 90% of its weight is fuel, which is typical for rockets.

The main engine is powered by  liquid oxygen and RP-1 – which

is a highly refined form of kerosene, similar to

jet fuel.

How does a rocket work? First, a rocket does not  rely on the atmosphere to oxidize the fuel like

a jet engine does. That’s because it carries  its own oxidizer. This

allows it to be able to function in outer  space where there is no atmosphere available.

A jet engine would not work here because  there is no oxygen available to burn the fuel.

Rocket engines are an application of Newton’s  third law, for every action, there is an equal

and opposite reaction. The combustion of  fuel causes high pressure exhaust gases

to be expelled at supersonic speed.  The rearward acceleration of the

mass of the fuel leaving the rocket  nozzle causes the equal and opposite

reaction of forward thrust powering the  rocket forward or upward during launch.

The shape of the nozzle of the rocket

is designed to increase the velocity of the  exhaust gases further to increase its thrust.

Highest thrust is achieved when the mass flow rate  of the fuel and exit velocity of the propellant

is high according to this equation.

The fuel has to be delivered at high volume and  pressure to get the thrust required for lift.

This pressure is provided by fuel pumps  that boost the pressure of the gases

before entering the combustion chamber.  Because these pumps can boost the pressure,

the fuels do not have to be pressurized so  high, and the thickness of their storage

tanks can be reduced resulting in weight  savings, and increased payload capacity.

Now you might ask, how are these pumps driven? They're typically driven by using a

small amount of fuel to drive a  turbine which drives the pump.

Maintaining a stable straight flight is an issue.  Early rockets were stabilized by large fins.

For stable flight the center of pressure  where the net aerodynamic force acts,

must be lower than the center of  gravity. This is because if its

angle of attack changes relative to its  flight path, the net force acting below the

center gravity cam restore the stability  that realigns the nose of the rocket.

Modern rockets don’t use fins though, because of the  extra weight and aerodynamic drag they cause.

Stability comes from swiveling the thrust nozzle  to keep it stable. This is called gimbaled thrust.

A geosynchronous orbit is achieved in stages.  Typically, the rocket will take the satellite

on its orbital altitude, but  the initial orbit is elliptical.

This elliptical orbit has to be changed to  a circular orbit to become geostationary.

So for example, An elliptical orbit may take the  satellite to an altitude of 150 km, at its

at its lowest point, called the perigee,  and to the geo stationary orbit of

35,786 km at its highest altitude, the apogee.  We can use Keppler’s laws to calculate the speeds

it will have at these points – about 36,500  km/hr at perigee, and 5800 km/hr at apogee.

The laws of physics are such that the  satellite continues on an elliptical orbit

until something changes its orbit. This  change is done by accelerating the rocket

at precisely the right time during its trajectory  so that it forms a more and more circular orbit

with every pass around the earth.

The thrusters have to be turned on precisely at  the apogee to accelerate the craft from 5800 km/hr

to 11,000 km/hr – which is the speed it needs to  have to maintain a circular geostationary orbit.

As you can probably surmise, there is only  one geostationary orbit and it is at 35,786 km

above the earth’s equator. There  is no other geostationary orbit.

And there are 500 satellites at that altitude.  This real estate, even in space is limited. The

total perimeter available is about 265,000 km.  This wouldn’t be a problem if each of the 500

satellites were placed equal distance apart,  there would be 500 km of space between them.

But that’s not the way the world works.  There are many more satellites above

the most developed regions of the earth.  They are sometimes less than 10 km apart.

And the speed with which they have  to move is 11,000 km per hour,

or 3 km per second, there is not much space.  They are less than 4 seconds apart. The real

estate here has is a prized commodity, as you might imagine, and is tightly controlled by an organization called, the

international telecommunications union (ITU) which  assigns each satellite a slot at this perimeter.

On addition, unless the rocket is launched from somewhere in the equator, it will have an orbit that is

not quite geo stationary because it will not be in  line or in the same plane relative to the equator.

So for example, when satellites are launched  from Cape Canaveral, Florida, which is located at about

28.5 degrees north latitude, the orbit will be  inclined 28.5 degrees from the equator. This has

to be adjusted. And this requires more fuel.

It is beneficial, therefore, for  countries to launch their rockets

as close to the equator as possible so that less  rocket fuel is needed to make this adjustment.

In addition, launching from close  to the equator gives the rocket

added inertia because of the earth’s greater speed  of spin near the equator, so that the launched

rocket will already be moving at the speed of  the earth's spin at the equator before the launch.

Note that not all communications satellites are  placed in geostationary orbits. Some are placed

in low earth orbit too. Low earth orbit satellites  can serve the same function, but you have to use

many of them as they are moving at such  high speeds. And there has to be constant

hand off of transmissions from one satellite  to another. But the advantage is that these

satellites are cheaper to launch and cheaper to  make because they don’t have to be as powerful,

since transmission distances are a lot shorter.

So what happens now, that we finally have  our satellite in orbit around the earth.

We have adjusted to make it a  circular geostationary orbit.

We have placed it in a correct  slot assigned by the ITU. And we

have adjusted its angle of orbit so that  it is in the same plane as the equator?

The first thing that happens is that solar  panels are deployed so that the satellite

can have power to function.

The main function of the satellite

is to receive signals from earth mainly  in the form of radio transmissions,

amplify them, and relay them back at a different  frequency back to the surface of the earth. The

shift in frequency is used to prevent interference  of incoming signals with outgoing signals.

Since radio waves are a form of electromagnetic  radiation, same as visible light,

they do not bend much around the curvature  of earth – photons are too fast after all.

The job of the satellite is to transmit  radio waves over long distances. Otherwise,

this would require a string of thousands of  relay stations on earth to do the same task.

These satellites usually have at least  two antennas which may be aimed at two

different points on the ground. Each is used  for both incoming and outgoing transmissions.

These antennas are generally made as large as  possible for greater sensitivity in receiving

signals from earth which can become quite faint  by the time they reach the satellite. But

the size is limited to about 10 feet diameter, or 3 meters, due to space restrictions inside the rocket.

Interestingly, a geostationary orbit is  sometimes called the "Clarke orbit," named

for science fiction writer Arthur C. Clarke, who  wrote "2001-A space odyssey." Believe it or not,

he was the first person to detail the usefulness  of such an orbit in a story he wrote back

in 1945. That tells you that science fiction  can sometimes foretell future science fact.

The next time you watch satellite TV, or  use your GPS app, listen to SiriusXM radio,

or check the weather, think about the  rocket science and the incredible technology

that goes into allowing us the privilege  to enjoy these fantastical technologies.

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If you want to give it a try for free, visit  squarespace.com/arvinash, and if you like it,

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And if you have a question, post it in the  comments below because I try to answer all of them.

I will see you in the next video my friend!