How do satellite communications work from space?
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How do satellite communications work from space?
The International Space Station (ISS) orbits the Earth about 217 miles (350 kilometers) above the Earth's surface. That's about 1,148,294 feet (yes, over a million feet) or 350,000 meters above you. That's some crazy altitude! The ISS and other satellite communications equipment have to be able to cover a ton of the Earth's surface from up there, right?
Maybe. Maybe not. Let's explore...
If the Earth were an apple
If the Earth is approximately the size of an average apple, how far away from it is the International Space Station in orbit (on a proportional basis)?
Maybe this far?
What to do when it’s so far?
No. It's only this far from the surface of the Earth's apple... 2.7 millimeters.
By the way…if the Earth were the size of an apple, your eyeball would be about the same size as our Moon.
Some people think that astronauts can see half of the Earth from the ISS, but in reality, they can only see a small portion of the entire Earth's surface (only about 3% at any given time). I'm sure it's still an awesome view from up there!
By the way…if the Earth were the size of an apple, your eyeball would be about the same size as our Moon.
Some people think that astronauts can see half of the Earth from the ISS, but in reality, they can only see a small portion of the entire Earth's surface (only about 3% at any given time). I'm sure it's still an awesome view from up there!
Satellite Type
Geostationary satellites (GEO) are placed in orbit about 22,236 miles (35,786 kilometers) above the Earth's surface. That's about 117,408,136 feet above you. At this distance, the satellite orbits the Earth once in 24 hours. That's about the speed at which the Earth rotates in one day. This allows a GEO satellite to hover in 1 specific position relative to the Earth. There are over 350 GEO satellites in orbit today.
From a person standing on Earth, these satellites appear to be perfectly still in the sky. But in reality, this satellite is orbiting the Earth at almost 2 miles per second! (3 km/s). This makes GEO satellites ideal for telecommunications by connecting 2 or more points/towers on Earth that are thousands of miles apart. This also provides fast data transmission to fixed antennas.
Newer and smaller satellites, called Low Earth Orbit (LEO) satellites, orbit closer to the Earth (as the name implies), but require more satellites to work together. These satellites are placed in orbit about 14,912 miles (24,000 kilometers) above the ground. These satellites are strategically placed in orbit and travel in different directions over the Earth while communicating with each other and various points on the Earth.
Their orbital positions and frequencies are regulated by the International Telecommunication Union, a United Nations agency, to avoid interference with signals from orbiting satellites. For the signals to be received back on Earth, receivers use antennas of various sizes, depending on several factors:
Satellite communication antennas are designed to cover a precise area anywhere from a country to an entire continent. Believe it or not, there are certain frequency bands that must be considered for satellites transmitting to locations where climate conditions often change or are extreme.
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