Did you know that there are currently 3,500 artificial satellites in motion, and that in addition to fulfilling scientific functions , some of them respond to commercial interests
? Did you know that the moon is the only non-artificial satellite that we have?
Below you will discover which are the most important and the amazing things about these human space contraptions. Keep reading, you will be surprised.

  • You can also read: The 8 planets of the solar system and their characteristics.

1. What are artificial satellites?
2. Functions of artificial satellites.
3. Types of artificial satellites.
4. Characteristics of artificial satellites.
5. The 10 most important artificial satellites. What are artificial
satellites? Artificial satellites are devices made for human beings launched into space so that, orbiting around a celestial body, they provide information of scientific interest . These high-precision machines are launched at a minimum speed of 8 kilometers per second so that they pass through the Earth’s atmosphere and remain in orbit.
Once in orbit, the satellite follows a marked route according to its objective, and continues to function for a certain time thanks to an energy charge. When the battery runs out, the satellite becomes unused, adding to what is considered “space debris”. Currently, it is estimated that there are 3,500 satellites in motion , and about 17,000 pieces of space debris.
These satellites were imagined by the human being several centuries ago, but Konstantin Tsiolkovski in 1903, and Herman Potocnik in 1928 laid the scientific foundations for the construction and launch of these machines. The cold war and the space race opened the possibility for its realization, materialized in 1957 by the Russians. Functions of artificial satellites
Most of the satellites have a scientific purpose, although we can also classify the types of satellites according to other functions. These are the main functions of satellites. 1. Scientific functions
Although there are more and more satellites for other purposes, most are artificial satellites built by scientific institutions to collect information about celestial bodies and the universe in general.
Satellites have been designed to obtain information on various aspectsrelated to our planet and beyond, such as the density and composition of the atmosphere, the ionized layers, the intensity of the thermal radiation received by the Earth, the measurement of interplanetary radiation or the evolution of sunspots. 2. Communication functions
It is one of the main functions of satellites today, since communication satellites allow television and radio waves to be broadcast from one point on Earth to any other place on the planet.
To understand how a communication satellite works, we have to imagine them with large antennas suspended above the earth. When a station emits a signal, the satellite picks it up and bounces it to other places.of the Earth that have a receiver. Due to the convenience of stationary orbits, most use a geostationary orbit. The space for communication satellites is limited , and this has caused a conflict between different countries to obtain transmission licenses. The entity that regulates transmissions and their concessions is the International Telecommunications Union. 3. Navigation
satellites The GNSS (Global Navigation Satellite System) is the global satellite navigation program that allows, through a network, to transmit signals for location and positioning on Earth for navigation and transportation purposes.
The best-known application of this type of navigation is the North American Global Position Satellite (GPS) system, which allows any geographical point to be recognized in real time and with high precision thanks to the coordinated action of 24 satellites.
Navigation satellites originate from the recognition of objects and people for military purposes, but today they are used, above all, for air navigation. They are also useful for orientation aid, timing, tracking devices used in wildlife (animal chips) and emergency locator system. 4. Reconnaissance satellites
They are also called spy satellites, since their main function is the photographic recognition of objects and people for military purposes. However, the utilities of this type of gadgets skyrocket, and allow, among other things, to detect nuclear tests anywhere in the world or act as a support object for tactical attack or defense maneuvers.
In recent years, these reconnaissance satellites or spy satellites have played a special role in the recognition and dismantling of terrorist cells .
The number and location of the spy satellites are jealously confidential, but it is known that the countries with the most spy satellites are the United States and Russia, followed by China, that there are several countrieswith orbital reconnaissance programs, among others Spain . 5. Meteorological
functions Artificial satellites with meteorological functions, responsible for collecting information on the atmospheric climate on Earth, are also well known.
Geostationary meteorological satellites are the most widely used for weather forecasts. Located high above the equator, they remain static with respect to the Earth’s rotational motion and can record or transmit images of the hemisphere below using infrared lights and sensors.
In addition, there are polar orbiting satellites, which move at much lower altitudes passing over the poles and can observe any place on earth, twice a day, with greater resolution. However, due to their cost, only the United States, Russia, China and India have polar-orbiting meteorological satellites.

  • It may interest you: The 8 most interesting mysteries about the Moon.

Types of artificial satellites according to the type of orbit
In addition to the classification according to the function they fulfill, this type of machine sent into space by human beings can be classified according to the distance at which these satellites are from the earth.
These are the three types of satellites by the type of orbit. 1. Low Earth Orbit
They are short-range satellites, since they orbit at a distance of between 700 and 1,400 km . Most of the satellites orbit at this altitude, which is why it is an increasingly saturated orbit, also due to the large presence of space debris.
The satellites that are in low Earth orbit travel around 27,400 kilometers per hour, going around the earth every 90 minutes. As advantages, low Earth orbit satellites require less energy and less powerful transmitters .
The most used satellites in low orbit are communication, remote sensing and earth observation. 2. Medium Earth orbit
Satellites that are located in a medium Earth orbit usually orbit at a distance of between 2,000 and 36,000 kilometers away from the Earth’s surface, and go around the globe in an average of 12 hours. Most medium orbit satellites are used for observation, defense, and positioning, like GPS.
In the medium orbit, Russia has developed the Molnya orbit, which is very elliptical and inclined to have high visibility from the polar areas. The advantage of this orbit is that it allows the Nordic countries to establish communications satellites for regions where geostationaries cannot reach. 3. Geostationary orbit
We have already discussed the geostationary satellites which, at a distance of about 35,700 km above the Earth’s equator, are used above all for climate monitoring. It was imagined as early as 1928 by Potocnik, and in 1945 it served as the basis for science fiction writer Arthur Clarke to devise a utopian planetary communications system .
all the satellites thatprovide internet, television, telephone and data to different points on Earth orbit at this height. Characteristics of artificial satellites
A satellite is an artificial solid body whose function is to orbit around a celestial body obtaining and emitting information. The characteristics of each satellite vary depending on its mission, but they share some common features. 1. Composition and materials of the structure
All the satellites have systems that guarantee their correct operation in orbit. The structure of the satellite is its skeleton, made up of metal trays that support the different equipment and serve as a protective screen against radiation, temperature changes and micrometeorites.
Normally, mixtures of light metals such as aluminum and titanium , or composite materials, which are formed from other different materials that, when together, offer special properties, are used for their construction. 2. Rocket
For a satellite to be put into orbit successfully it has to be propelled from Earth with a rocket at a speed of about 8 kilometers per hour , and the one in charge of doing it is a rocket that, once reached the appropriate height and through signals from the control center on Earth, it releases the satellite, which descends to orbit.
The rocket is mounted on a platform pulled by a traction system to the launcher. inside the rocketThe ideal thermal conditions are foreseen so that the satellite structure does not suffer any damage, and the external climatic conditions must be ideal.
The rockets also have a safety explosive system , in such a way that if there is an error in the ascent process or the rocket loses speed and descends, the control center can activate the preventive explosion so that the satellite does not cause damage. 3. Guidance
system The Attitude, Control and Security determination system of an artificial satellite serves to correct the orbital trajectory , always under the orders of the central control, which has several mechanisms to guide the actions of the device.
In this case, when you want to correct a direction, the guidance system releases gases in the opposite direction to which you want to orient the satellite, and its position is controlled by means of a reaction wheel.
Today, satellites are powered by solar panels , which guarantee the necessary energy reserves to stay in orbit. 4. Sensors
The satellite sensors capture information that is later distributed to the control center for its use, but in addition, these sensors allow the control center to know exactly and in real time the situation of the parts of the satellite and the conditions of the surrounding environment.
In addition, all satellites have a payload, which is made up of a series of observation systems, cameras, lenses , infrared sensors, X-rays and radars or simply antennas for transmitting and receiving frequencies to obtain information. 5. Communications exchange system
To communicate with the earth, the satellite has a specific communications exchange system made up of antennas, radiofrequency receivers, signal amplifiers and transponders. The 10 most important artificial satellites
Since the Russians successfully launched the first artificial satellite in 1957, the presence of these devices in space has not stopped growing, with various functions and features that will surprise you. 1. Sputnik
At the dawn of the cold war, the Soviet Union surprised in 1957 with a historic feat: the launch of the first artificial satellite. The “Sputnik” was a metal sphere 58 centimeters in diameter and weighing just over 80 kilos that took, on its first trip, 98 minutes to go around the Earth.
Although its objectives were limited in scope (obtaining information from the upper layers of the atmosphere and the planet’s electromagnetic field), in reality Sputnik had a much more important role asSoviet propaganda engine and pioneering experiment in expanding the frontiers of space conquest.
Sputnik, in Russian, means satellite and started the space race between Russians and Americans . 2. Explorer 1
Sputnik accelerated the space race and only a year later the Americans managed to put their first artificial satellite into orbit, “1958 Alpha 1”, better known as Explorer 1. It managed to detect the Van Allen radiation belts , Named after James Van Allen, director of the design and construction of Explorer 1.
The American satellite had a cylindrical shape, 2 meters long and 15 centimeters in diameter, and weighed almost 14 kilos. Wasequipped with two fiberglass antennas for capturing and recording information, and on its first flight it took 114 minutes to go around the Earth.
Explorer 1 was launched on January 31 and on May 23 it stopped emitting signals, although it remained in orbit for twelve years until it was destroyed during the fall. 3. Meteosat
Surely the best known satellite in Spain is Meteosat and, as its name suggests, it is an artificial meteorological satellite whose function is to monitor the Earth’s climate. Actually, Meteosat is not a satellite but a group of satellites whose system was launched in 1977, although the second generation have been in operation since 2002.
This group of satellites were placed in geostationary orbit through the European Space Agency over the Atlantic Ocean in order to provide meteorological information from Africa and Europe.
Through the Meteosat satellite we obtain information on temperature, altitude, speed and direction of the wind , temperature and altitude of the nines, humidity, ozone concentration and temperature at ground level. The satellite offers a series of images in different bands, from ultraviolet to infrared. 4. Disaster Monitoring Constellation
Disaster Monitoring Constellation (DMC) are five artificial satellites designed and built by Surrey Satellite Technology, and operated by the governments of Nigeria, Algeria, Turkey, Great Britain and China. The satellite has a sophisticated system for obtaining images that allow knowing emergency situations on Earth and preventing disasters.
In fact, the DMC satellite is a perfected reproduction of the Landsat, but it surprises with its technological precision. Thanks to its system, it has managed to monitor disasters such as the Indian Ocean tsunami in 2004, Hurricane Katrina in 2005 and other natural disasters.
One of these satellites is responsible, for example, for monitoring the Greenland ice sheet, the most sensitive of all to global warming, because if it melted it would increase the level of evil by 7 meters. The device provides information on the decrease in the thickness of the cap, the movement of the masses of water that are generated on its edges and the influence on sea currents. 5. Landsat 8
The generation of Landsat satellites was a revolution for obtaining images of the earth through a sophisticated space photography system . Until now, this system of satellites operated by the United States has evolved to eight types of gadgets, with constant improvements and improvements that make it more powerful.
The latest, Landsat 8, has served, for example, to perfect the well-known Google Earth exploration and mapping system. Thanks to Landsat 8, Google Earth offers sharper and more precise images of all geographic points on Earth.

  • Also consult the NASA image bank.

Among other advantages, Landsat 8, launched into orbit in 2013, allows twice as many images to be captured and is therefore constantly updated. The satellite completes its orbit at a height of 705 km every 99 minutes , and revisits the same point on the earth’s surface every 16 days. Get 650 images daily. 6. GOCE What is the shape of the earth? This question motivated the creation and launching into orbit of the Gravity Ocean Circulation Explorer (GOCE) on March 17, 2009 by the European Space Agency. Its mission was to determine the anomalies of the Earth’s gravitational field and determine the shape of the Earth with an accuracy of 1 to 2 centimeters.
The peculiarity of this satellite is that, although it weighed 1,100 kilos, thanks to ainnovative ion engine managed to stay four years in orbit at a very low altitude, 260 km. On October 21, 2013, it re-entered the atmosphere and disintegrated without causing any damage.
Thanks to GOCE we have a much more detailed knowledge of the shape of the geoid , the hypothetical body that would form a global ocean at rest, information that is being used to study the sea level and the interior of the Earth. 7. Intelsat and Hispasat
Intelsat is the most extensive network of communication satellites in the world, and its most important satellite is Intelsat 1R. This took off aboard a rocket on November 15, 2000, and its mission was at various levels: telecommunications, digital video and Internet. Its long range reception allowed it to cover parts of Europe, North America and North Africa.
The Spanish satellite operator is called Hispasat, with coverage in America, Europe and North Africa since 1989. Hispasat’s fleet of satellites allows the distribution of more than 1,250 television and radio channels to more than 30 million homes. 8. Minisat
On April 21, 1997, the Minisat, weighing 200 kilos , was launched from the Grando air base in the Canary Islands . This group of satellites was designed, built and put into orbit by the National Institute of Aerospace Technology in the 1990s, and was the first mini-satellite orbited by Spain. The Minisat orbited until 2002 at an altitude of 11,000 meters. After takeoff, the instruments released the satellite in free fall, and for 5 minutes, the rocket began its march until it reached its orbit at a distance of about 600 km. 9. EECS
The most complex and expensive space system in the world, that of the United States, is also the most secret, since it has an entire network of spy satellites that had remained hidden for years. But in 2013 the names of several of those satellites detailed in a secret Pentagon report and brought to light by Edward Snowden in the Washington Post were revealed.
Within those satellites, reference was made to the Evolved Enhanced CRYSTAL System. Until now, it was believed that the KH-11 were the latest generation spy satellites, but the name of this group appears in the document, which, with military objectives, cost 1,250 million dollars in 2012 and 1,550 in 2013 .
In addition, the report reveals, among others, the names of the satellites, hitherto unknown, to spy on the enemy’s communications and electronic systems. 10. Chang’e-4
On December 12, the Chinese space probe Chang’e-4 slowed down and entered lunar orbit achieving a first step for a whole feat: the first controlled landing in history on the far side of the Moon. Moon.
After flying for 110 hours, the control center in Beijing ordered the deceleration to 129 km from the moon , and the next step is to adjust the orbit and check the transmission between the probe and the Queqiao satellite so that the control center decides the right time to land.
Since the cycle of translation of the moon is the same as that of rotation, it is always the same side that faces the Earth, while there is a part that is always hidden .
The Chang’e-4 is tasked with conducting low-frequency radio astronomical observation, terrain and relief analysis , and determining the mineral composition and structure of the lunar surface, among others.

  • You can also read: 15 curiosities about outer space that you did not know.