Whether it’s to find out new information about the wonders of space and keep a close eye on our atmosphere, to make sure you can call your parents from the other side of the world, to broadcast television programs, or to help us find our way around planet Earth, satellites have become an essential part of our lives.
Satellites are the result of expert engineering and come in many shapes and sizes.
Many of us take satellites for granted because they’re out of sight, spinning in orbit far above us. But how are satellites controlled from Earth? Read on to find out.
Satellites are like mirrors in space. We send a signal out to space and it bounces back to Earth and to the required destination. Satellites help us navigate Earth’s limitations by sitting just outside of them.
We normally place satellites into groups according to their function or orbit. A satellite’s function determines the distance from Earth it needs to be, its required speed, and which orbit it follows.
Communications satellites utilize radio waves by sending them from one destination on Earth to another by capturing the signals fired up from a ground station, or satellite dish on Earth.
The signals are amplified by the satellites so they are strong enough to continue, then they are bounced back down to the required ground station.
Communication satellites defeat the issue of sending radio waves in straight lines around a spherical planet.
They have made our planet interconnected and have therefore advanced our species greatly through the means of global communication.
How Do Communications Satellites Work?
Communications satellites work through the use of uplinks and downlinks. Uplinks involve data being sent up to the satellite from a ground station.
The satellite processes this data using transponders such as radio transmitters and amplifiers, which strengthen the signals and modify their frequency, so that incoming data doesn’t get mixed up with outgoing data.
Specific transponders within the satellite are used for different functions.
For example, different TV stations are controlled by separate transponders at different frequencies.
Downlinks, on the other hand, involve data being beamed back down from the satellite to a new ground station on Earth which is different from the sender.
When a phone call is being sent up, there is only one uplink and a downlink, however, for things such as TV broadcasting, there is normally one or more uplink and multiple downlinks, allowing multiple viewers.
Because satellites work using radio waves (which travel at the speed of light) the signal only takes a few seconds to reach the required destination.
What Are The Different Orbits Followed By Satellites?
Satellites follow different orbits at different heights depending on their grouping. These are low-earth orbits, medium-earth orbits, and high-earth orbits.
What Are Low-Earth Orbits?
Scientific satellites are normally quite near to the Earth, tending to be a few hundred kilometers high.
They follow a relatively circular orbit and move extremely fast around the Earth to avoid the effects of gravity.
They have quite a small orbit because they’re so close to the Earth, but have good coverage across large regions of the world because of how quickly they orbit.
Some low-earth orbits follow a polar orbit, which causes them to move over both the North and South poles in just over an hour and a half.
What Are Medium-Earth Orbits?
Medium-earth orbits are around ten times higher than low-earth orbits. Navigation satellites used for GPS tend to follow a medium-earth orbit.
These orbits are known as semi-synchronous, meaning that even though they’re not always in the same place directly above us, they move above the same points on the equator at the same time every day.
The higher up a satellite, the more time it spends in certain regions of the Earth.
What Are High-Earth Orbits?
Satellites in high-earth orbits operate at a distance of about 36,000 km from the Earth’s surface.
This specific position makes sure that they take exactly one full day to orbit the Earth and always come back to the exact same position at the same time.
This specific type of high-Earth orbit is referred to as geosynchronous, due to its synchronization with the rotation of Earth, or geostationary because it remains over the same point at all times.
In modern times, satellites are significant to our lives and help us to do many of the things we take for granted, such as making phone calls and watching TV, checking the weather, or driving to an unknown location with GPS.
Without many of these functions, a lot of us would be lost (literally). Satellites are an ingenious invention, dating right back to 1958 when the first successful satellite was launched (Explorer 1).
It’s easy to see how much our species has advanced since we decided to send satellites into space, so maybe our lives would be enhanced even further if we continue to explore the wonders of space.
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