How Does a Rocket Work?

Rockets are the perfect way to get around in space. But how do they work?

Space travel and rockets, it’s like ice cream and apple pie, or ice cream and apple pie and my face. They just go together. They belong together.
But what if I’m allergic to rockets, or have some kind of cylindrical intolerance, or flaming column sensitivity that makes me hive out? Why can’t I fly to space in balloons or airplanes or helicopters? Why do we need these pointy cubist eggplant flame tubes?
The space age followed the development of powerful V2 rockets in WW II. They could hit targets 320 km away and reach an altitude of 200 km. They were a new kind of war machine, a terrifying weapon that could hurl payloads of destruction from the skies. But this terrifying development is what brought us our modern rockets as their propulsion system can work up where there’s no air, in the vacuum of space.

Dr. Robert H. Goddard (second from right) and his colleagues hold a liquid-propellant rocket in 1932 at their New Mexico workshop. Credit: NASA Goddard Space Flight Center

How do they actually work? It all comes down to that “every action, equal and opposite reaction” thing that Newton was always going on about.
If you take a balloon, fill it with air, and then let it go. All that air rushing out propels the balloon around. This kind of balloon rocket would work perfectly well in space too although it might be a little too fragile and unpredictable to want to strap yourself to.
If we take that idea and scale it up, add some fuel tanks and fins, attitude control and optionally: astronauts. We’ve got ourselves a rocket. It works by pushing “stuff” out one end of a tube at the highest possible velocity. The faster you can blow stuff out the end, the faster the tube itself is going to go.
This means rocket science is really all about how to get the exhaust gases hurling out the backside of the rocket as quickly and forcefully as possible. The fuel can be solid, like the space shuttle’s solid rocket boosters. Or the fuel can be liquid, like the shuttle’s main fuel tank filled with liquid oxygen and hydrogen.

Liquid-Propellant Rocket

This fuel is ignited and completely converted into exhaust gases which blast out of the rocket’s nozzles at high velocity. Really, really high velocity.
The scary part for passengers is that modern rockets are mostly made of fuel. In fact, the weight of the space shuttle’s fuel was 20 times more than the weight of the shuttle itself. Which I believe really puts a fine point on the bravery of any astronaut. Think of a rocket as a beer can, filled with explosives, that you strap yourself to the outside of. To make a rocket go faster and shorten the travel time, you want to kick material out at a higher velocity.
NASA has experimented with ion drives for some of its missions. These highly efficient engines use electric fields to accelerate particles of xenon at much higher velocities. Even though they use a fraction of the amount of fuel, ion engines can reach much higher speeds because of the high exhaust velocity.

The Vasimir experiment (Ad Astra Rocket Corporation)

And even higher velocity rockets have been tabled, such as the VASIMIR engine and even antimatter engines. So how do rockets work? Just like deflating balloons, only bigger. Much much bigger. And full of explosives and modeled on a horrible and terrifying weapon from the second world war. Really, not much like a balloon at all…

About Satellites

About the Communications satellite

From Wikipedia, the free encyclopedia

  (Redirected from communication satellite)

An Advanced Extremely High Frequency communications satellite relays secure communications for the United States and other allied countries.

Communications Satellites act as the middleman in the realm of telecommunications. These satellites are specifically designed to relay information from a source to a receiver. Types of information that can be transferred include: television, telephone, radio, internet, and military. As of May 11, 2015, there are over 2,000 communications satellites in Earth’s orbit that are being used by private and government organizations.
In order to communicate wirelessly, signals must be sent using electromagnetic waves. However, these waves cannot bend around the curvature of the Earth. So, in order for people to communicate over long distances, a satellite (or multiple satellites) must be used to help redirect the signals.
There are two major classes of communications satellites. The first class is called the “passive satellite”. This type of satellite only redirects the signal coming from the source, and points in the direction of the receiver. With passive satellites, the transmitting signal has the tendency to be weak. This is because, as the electromagnetic wave moves through the atmosphere, particles will interrupt the wave and cause it to be muffled. Active satellites, on the other hand, allow for a signal that is much more clear. These satellites can take a signal that they receive, and amplify it to make it clearer. However, these satellites will often times amplify unwanted signals. Because of this, they also need a processor on board. A processor will filter out any of the unwanted amplified signals before sending it back down to earth.
There are three major ways in which communications satellites orbit the Earth. One of these orbits is called geosynchronous Earth orbit (GEO), which is 19,300 nautical miles from Earth’s surface. This orbit has the special characteristic in which satellites placed in this orbit can “stand still” with respect to a certain location on earth. That is, if a viewer on Earth were to look up into the sky and spot a satellite in GEO, it would seem as if it isn’t moving. Below GEO is medium Earth orbit (MEO). It ranges from 500-1200 nautical miles above Earth. Below MEO is low Earth orbit (LEO) and is about 200 nautical miles above Earth. MEO and LEO are not able to keep satellites “stationary” like GEO, so more satellites would be needed to cover a certain area. However, they transmit clearer signals because of their relatively small distance to the earth. In this case, the contractor must make a decision to use more satellites in order to have a clearer signal, or use one satellite while having a muffled signal.
The electromagnetic signals that communication satellites work with, have a large spectrum of wavelengths and frequencies. To keep these waves from interfering with one another, the United States and other international organizations have certain rules and regulations describing which wavelength a certain company or group can use. By separating out wavelengths, communication satellites will have minimal interference and be able to communicate effectively.    




^{As published on ; 11th June 2005}