A celestial body that orbits another larger celestial body is a satellite. An artificial satellite is a manufactured object or vehicle intended to orbit the earth, moon, or other celestial body. Since October 4, 1957, humanity has been able to put artificial satellites in orbit around the Earth. The Russians were the first with Sputnik; a small satellite that orbited the Earth for a couple of months and transmitted beeps for 21 days.
The United States launched its first satellite on January 31, 1958. This satellite was named Explorer 1 and, through data transmitted to Earth by Explorer 1, scientists discovered the Van Allen radiation belts, the areas in the space around the Earth and the planets Jupiter. and Saturn, which contains high-energy protons and electrons.
50 years ago there were no artificial satellites. Since Sputnik, governments and private companies around the world have launched more than 4,800 satellites. Satellites are used for satellite television, of course, but there are many more purposes for satellites.
Types of satellites
The Moon is a satellite of the Earth; the earth is a satellite of the sun. The first is called the moon, the second planet. Man-made (artificial) satellites orbit any celestial body and are always called a satellite, whether they orbit the earth, the moon, the sun, or any other celestial body.
We use satellites for different purposes and all satellites can be placed in one of the following categories:
The distribution of television and audio signals, and the telephone connections via satellite are carried out by means of communication satellites. These types of communications often require a satellite in geostationary orbit. In 1964, the United States Department of Defense launched the first satellite to be placed in geostationary orbit. This satellite was called Syncom 3.
Today, geostationary satellites are used to provide voice, audio and video communications such as Dish Network Satellite television.
These satellites were of enormous help to transport companies, especially water and air transport. US GPS satellites are in Low Earth Orbit (LEO) and can determine position to within 1 cm (0.4 in). However, such precise positioning is available only for military purposes. For commercial use, the precision is less precise.
Navigation satellites are also used to measure distances, for example between buildings.
Observing the earth is the task of meteorological satellites and, above all, what happens in the atmosphere. Different types of cameras, such as infrared and normal cameras, are used to observe the same part of the earth, from geostationary orbit, or more closely from polar orbits to obtain more detailed images. These low-orbit weather satellites are more focused on studying the atmosphere than on the current weather itself.
Very similar to weather satellites, military satellites are also used to observe the Earth. Generally, with higher resolution cameras and instead of normal communications equipment, they also use encryption. Sometimes these types of satellites have very different types of orbits. For example, a highly elliptical orbit that takes the satellite as far from the earth as the moon and so close to the earth that it soon enters the atmosphere, to get as close to the earth’s surface as possible without falling back to earth.
Many more tactics are probably used, but for obvious reasons these are unknown.
Observing the earth for scientific purposes is also very possible with satellites. Mapping with satellites of low polar orbits, for example, but also measuring the exact shape of the earth, geological research, etc. they can benefit greatly from science satellites.
But science satellites aren’t just used to observe Earth. Space research also benefits from science satellites. For example, the Hubble satellite, which is actually a huge telescope orbiting the Earth. Because the Hubble telescope does not have to “see” through the atmosphere, it can produce much clearer and more detailed images than ground-based telescopes.