ROCKET SCIENCE explained in 15 minutes! And How do satellites work?
Summary
TLDRThis 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
🚀 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.
🔧 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.
🌐 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.
Mindmap
Keywords
💡Rocket Science
💡Communications Satellites
💡Geostationary Orbit
💡Orbital Mechanics
💡Newton’s Laws of Universal Gravitation
💡Atlas V
💡Rocket Propulsion
💡Gimbaled Thrust
💡International Telecommunication Union (ITU)
💡Geostationary Orbit Real Estate
💡Low Earth Orbit (LEO)
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.
I’m excited to tell you about Square Space, today’s sponsor.
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If you want to give it a try for free, visit squarespace.com/arvinash, and if you like it,
you can even get 10% off your very first purchase by clicking the link in the description below.
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!
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