Merdeka.com – Serving as eyes in the sky and space mirrors reflecting phone calls from Earth are two of the main functions of satellites for human life. Thousands of carefully engineered satellites fly around Earth’s sky, invisible to the naked eye.
Satellites, which are out of sight and out of mind, may often be underestimated by humans. In fact, satellites play an important role in everything from TV broadcasts to transcontinental phone calls to weather forecasts and the Internet.
A satellite is a moon, planet, or machine that orbits a planet or star. For example, Earth is a satellite because it orbits the sun. Likewise, the moon is a satellite because it orbits the Earth. Usually, the word “satellite” refers to a machine that is launched into space and moves around the Earth or other object in space.
However, what exactly are satellites and how do they work? The following is complete information that is interesting to learn, reported from nasa.gov.
Know What is a Satellite
A satellite is any object that moves in a curved path around a planet. The Moon is Earth’s original natural satellite, and there are also many man-made satellites, which usually circulate closer to Earth. The path that a satellite travels is an orbit, which is sometimes circular.
To understand why satellites move in a circle, you must first understand Newton’s principle of force. Newton proposed that the force of gravity exists between any two objects in the universe. If it weren’t for this force, a satellite moving near a planet would continue to move at the same speed and direction, in a straight line.
However, the satellite’s straight-line inertial path is offset by the strong gravitational attraction directed towards the center of the planet. Sometimes, a satellite’s orbit looks like an ellipse, a squashed circle moving around two points known as foci. The same basic laws of motion apply, except that the planet is located at one of the foci.
As a result, the net force applied to the satellite is not uniform throughout the orbit, and the speed of the satellite changes constantly. It moves fastest when it is closest to the planet, at a point known as perigee, and slowest when it is farthest from the planet, at a point known as apogee.
Some satellites take pictures of the planet that help meteorologists predict the weather and track storms. Some satellites take pictures of other planets, suns, black holes, dark matter, or distant galaxies. These images help scientists better understand the solar system and the universe.
Other satellites are still used primarily for communications, such as transmitting TV signals and telephone calls around the world. A group of more than 20 satellites makes up the Global Positioning System, or GPS. These satellites can help determine your exact location.
The Important Role of Satellite
The wide view that the satellite has allows it to observe a large area of the Earth at one time. With this capability, satellites can collect more data more quickly than instruments on the ground.
Satellites can also see into space better than telescopes at the Earth’s surface. That’s because satellites fly above clouds, dust, and molecules in the atmosphere that can block views from ground level.
Before satellite, TV signals couldn’t reach very far. The TV signal only travels in a straight line. So, this signal will quickly go into space instead of following the curve of the Earth. Sometimes, mountains or tall buildings can even block this TV signal.
Phone calls to faraway places are also a problem. Installing telephone wires long distances or underwater is a difficult thing to do, and even if done, it would cost a lot of money.
But with satellite, TV signals and phone calls are sent upwards. Then, almost instantly, the satellite can send them back to a different location on Earth. This certainly facilitates human activities.
Types of Satellites and Their Uses
Satellites come in various types and sizes. Satellites also play various roles. The following are some types of satellites and their uses;
- Weather satellites help meteorologists predict the weather or see what’s happening right now. Geostationary Operational Environment Satellite (GOES) is an example. These satellites generally contain cameras that can return photos of Earth’s weather, either from a fixed geostationary position or from polar orbits.
- Communication satellites allow telephone conversations and data to be forwarded via satellite. Common communications satellites include Telstar and Intelsat. The most important feature of a communications satellite is a transponder, or radio that receives a conversation on one frequency and then amplifies it and sends it back to Earth on another frequency. A satellite usually contains hundreds or thousands of transponders. Communication satellites are usually geosynchronous.
- Broadcast satellites broadcast television signals from one point to another (similar to communications satellites).
- Scientific satellites, such as the Hubble Space Telescope, perform all manner of scientific missions. They see everything from sunspots to gamma rays.
- Navigation satellites help ships and planes navigate. The most famous is the GPS satellite NAVSTAR.
- Rescue satellites respond to radio distress signals.
- Earth observation satellites check the planet for changes in everything from temperature to greenery to ice sheet coverage. The most famous is the Landsat series.
- Military satellites also exist, but most of the information is classified. Applications may include relaying encrypted communications, nuclear monitoring, observing enemy movements, early warning of missile launches, eavesdropping on terrestrial radio links, radar imaging and photography (using large telescopes that take pictures of areas of military interest).
How Communication Satellites Work
Satellites tend to be grouped according to their occupation or the orbits they follow. These two things are closely related, because the work a satellite does usually determines how far it is from Earth, how fast it must move, and the orbit it must follow. The three main uses of satellites are;
- Photography, imaging and scientific surveys
The workings of communication satellites are described as follows. Communication satellites are “space mirrors” that can help reflect radio, TV, Internet data, and other types of information from one side of the Earth to the other. If you want to send something like a TV broadcast from one side of the Earth to the other, there are three ways satellites work involved.
First, there is the uplink, where data is transmitted to the satellite from an earth station on Earth. Second, the satellite processes data using a number of onboard transponders (radio receiver, amplifier, and transmitter). This boosts the incoming signal and changes its frequency, so that the incoming signal is not confused with the outgoing one.
Different transponders on the same satellite are used to handle different TV stations being carried on different frequencies. Third, there is the downlink, where data is sent back to another earth station elsewhere on Earth.
The way a satellite works is almost the same as a vehicle in general, because a satellite also has two main parts, namely the public vehicle itself and the special thing it carries (load) to perform its unique task.
The “vehicle” part of the satellite is called the bus, and this includes the outer casing, solar panels and batteries that provide power, telemetry (a remotely controlled system that sends monitoring data from the satellite to Earth and operational commands back in the other direction), boosters rockets to keep them in position, and reflective materials or other systems (“heat pipes”) to protect them from solar radiation and dissipate heat.
Meanwhile, the payloads carried by the satellites are transponders for communication satellites, computers and atomic clocks to generate time signals for navigation satellites, cameras and computers for images back into digital data for photographic satellites, and so on.
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