Why do we need an artificial earth satellite? What is a satellite? What is the difference between a satellite and space debris
Satellites and planets of the solar system
The natural satellites of planets play a huge role in the life of these space objects. Moreover, even we humans are capable of feeling the influence of our planet’s only natural satellite – the Moon.
The natural satellites of the planets of the solar system have aroused keen interest among astronomers since ancient times. To this day, scientists are studying them. What are these space objects?
Natural satellites of planets are cosmic bodies of natural origin that orbit around planets. The most interesting for us are the natural satellites of the planets of the solar system, since they are in close proximity to us.
There are only two planets in the solar system that do not have natural satellites. These are Venus and Mercury. Although it is assumed that Mercury previously had natural satellites, this planet lost them in the process of its evolution. As for the rest of the planets in the solar system, each of them has at least one natural satellite. The most famous of them is the Moon, which is our planet’s faithful cosmic companion. Mars has, Jupiter -, Saturn -, Uranus -, Neptune -. Among these satellites we can find both very unremarkable objects, consisting mainly of stone, and very interesting specimens that deserve special attention, and which we will discuss below.
Classification of satellites
Scientists divide planetary satellites into two types: satellites of artificial origin and natural ones. Satellites of artificial origin or, as they are also called, artificial satellites are spacecraft created by people that make it possible to observe the planet around which they orbit, as well as other astronomical objects from space. Typically, artificial satellites are used to monitor the weather, radio broadcasts, changes in the topography of the planet's surface, and also for military purposes.
The ISS is the largest artificial satellite of the Earth
It should be noted that it is not only the Earth that has satellites of artificial origin, as many people believe. More than a dozen artificial satellites created by mankind revolve around the two closest planets to us - Venus and Mars. They allow you to monitor climate conditions, changes in terrain, and also receive other relevant information regarding our space neighbors.
Ganymede is the largest moon in the solar system
The second category of satellites - natural satellites of planets - is of great interest to us in this article. Natural satellites differ from artificial ones in that they were created not by man, but by nature itself. It is believed that most of the satellites of the solar system are asteroids that were captured by the gravitational forces of the planets of this system. Subsequently, the asteroids took on a spherical shape and, as a result, began to revolve around the planet that captured them as a constant companion. There is also a theory that says that the natural satellites of planets are fragments of these planets themselves, which for one reason or another broke away from the planet itself during the process of its formation. By the way, according to this theory, this is how the Earth’s natural satellite, the Moon, came into being. This theory confirms chemical analysis of the Moon's composition. He showed that the chemical composition of the satellite is practically no different from the chemical composition of our planet, where the same chemical compounds are present as on the Moon.
Interesting facts about the most interesting satellites
One of the most interesting natural satellites of the planets of the solar system is the natural satellite. Charon, in comparison with Pluto, is so huge that many astronomers call these two space objects nothing more than a double dwarf planet. The planet Pluto is only twice the size of its natural satellite.
The natural satellite is of keen interest to astronomers. Most of the natural satellites of the solar system's planets are composed primarily of ice, rock, or both, resulting in them lacking an atmosphere. However, Titan has this, and quite dense one, as well as lakes of liquid hydrocarbons.
Another natural satellite that gives scientists hope for discovering extraterrestrial life forms is Jupiter’s satellite. It is believed that under the thick layer of ice that covers the satellite there is an ocean, within which there are thermal springs- exactly the same as on Earth. Since some deep-sea life forms on Earth exist thanks to these sources, it is believed that similar life forms may exist on Titan.
The planet Jupiter has another interesting natural satellite -. Io is the only satellite of a planet in the solar system on which astrophysicists first discovered active volcanoes. It is for this reason that it is of particular interest to space researchers.
Natural satellite research
Research on the natural satellites of the planets of the Solar System has interested the minds of astronomers since ancient times. Since the invention of the first telescope, people have been actively studying these celestial objects. The breakthrough in the development of civilization made it possible not only to discover a colossal number of satellites of various planets of the solar system, but also to set man on the main, closest to us, satellite of the Earth - the Moon. On July 21, 1969, American astronaut Neil Armstrong, together with the crew of the Apollo 11 spacecraft, first set foot on the surface of the Moon, which caused rejoicing in the hearts of humanity at that time and is still considered one of the most important and significant events in space exploration.
In addition to the Moon, scientists are actively studying other natural satellites of the planets of the solar system. To do this, astronomers use not only visual and radar observation methods, but also use modern spacecraft, as well as artificial satellites. For example, the “” spacecraft for the first time transmitted to Earth images of several of Jupiter’s largest satellites:,. In particular, it was thanks to these images that scientists were able to record the presence of volcanoes on the moon Io, and the ocean on Europa.
Today, the global community of space researchers continues to be actively engaged in the study of the natural satellites of the planets of the solar system. In addition to various government programs There are also private projects aimed at studying these space objects. In particular, the world-famous American company Google is currently developing a tourist lunar rover, on which many people could take a walk on the Moon.
Galaxy star system Milky Way, in which we live, includes the Sun and 8 other planets revolving around it. First of all, scientists are interested in studying the planets closest to Earth. However, the satellites of the planets are also very interesting. What is a satellite? What are their types? Why are they so interesting for science?
What is a satellite?
A satellite is a small body that rotates around a planet under the influence of gravity. Currently, we know of 44 such celestial bodies.
Only the first two planets of our star system, Venus and Mercury, have no satellites. The Earth has one satellite (the Moon). The “Red Planet” (Mars) has 2 celestial bodies accompanying it - Deimos and Phobos. The largest planet in our star system, Jupiter, has 16 satellites. Saturn has 17, Uranus has 5, and Neptune has 2.
Types of satellites
All satellites are divided into 2 types - natural and artificial.
Artificial - celestial bodies created by people, which open up the opportunity to observe and explore the planet, as well as other astronomical objects. They are necessary for drawing maps, weather forecasts, and radio broadcasting of signals. The largest man-made "fellow traveler" of the Earth is (ISS). Artificial satellites are not only found on our planet. More than 10 such celestial bodies revolve around Venus and Mars.
What is a natural satellite? They are created by nature itself. Their origin has always aroused genuine interest among scientists. There are several theories, but we will focus on the official versions.
Near each planet there is an accumulation of cosmic dust and gases. The planet attracts celestial bodies that fly close to it. As a result of such interaction, satellites are formed. There is also a theory according to which fragments are separated from cosmic bodies colliding with a planet, which subsequently acquire a spherical shape. According to this assumption, there is a fragment of our planet. This is confirmed by the similarity of the terrestrial and lunar chemical compositions.
Satellite orbits
There are 3 types of orbits.
The polar plane is inclined to the equatorial plane of the planet at a right angle.
The trajectory of the inclined orbit is shifted relative to the equatorial plane by an angle of less than 90 0 .
Equatorial (also called geostationary) is located in the plane of the same name, along its trajectory heavenly body moves at the speed of the planet's revolution around its axis.
Also, the orbits of satellites according to their shape are divided into two basic type- circular and elliptical. In a circular orbit, a celestial body moves in one of the planes of the planet with a constant distance above the surface of the planet. If the satellite moves in an elliptical orbit, this distance changes within the period of one orbit.
Natural satellites of the planets of the solar system: interesting facts
Saturn's moon Titan has its own dense atmosphere. On its surface there are lakes containing liquid hydrocarbon compounds.
Following the USSR and the United States, satellites were launched by France (1965), Australia (1967), Japan (1970), China (1970) and Great Britain (1971).
The implementation is based on international scientific and technical cooperation. For example, countries friendly to the USSR launched satellites from Soviet spaceports. Some satellites, manufactured in Canada, France, and Italy, have been launched since 1962 using launch vehicles developed by the United States.
What is a cosmic body rotating in orbit around a particular planet? By origin they are natural and artificial. The world community is of particular interest natural satellites planets, because they still conceal many mysteries, and most of them are still waiting to be discovered. There are projects to study them of private, state and global significance. Artificial satellites make it possible to solve applied and scientific problems both on the scale of an individual planet and the entire outer space.
In a broad sense, a companion is a fellow traveler or comrade, someone who accompanies someone on a journey. But not only people have satellites. Planets also have their “fellow travelers”. What are they? When first appeared artificial satellite?
The emergence of satellites
In astronomy, the concept of “satellite” first appeared thanks to the scientist Johannes Kepler. He used it back in 1611 in his work Narratio de Iovis Satellitibus. In the usual sense, planetary satellites are cosmic bodies that revolve around planets. They rotate in their own orbit under the influence of the gravitational forces of their “senior companion”.
Natural satellites are bodies that appeared naturally, without human intervention. They can be formed from gas and dust or from a fragment of a celestial body, captured by the gravitational forces of the planet. When they come under the influence of gravitational forces, they are transformed, for example, they compress and become denser, acquire a spherical shape (not always), etc.
It is assumed that most of the modern satellites of the planets are their fragments, broken off as a result of a collision, or former asteroids. As a rule, they consist of ice and minerals, unlike planets, do not have a metallic core, and are dotted with craters and faults.
When you open a satellite, it is assigned a number. Then the discoverer has the right to name it at his own discretion. Traditionally, their names are associated with mythology. Only Uranus has them named after literary characters.
Satellites of the planets
Planets can have a wide variety of “companions.” The Earth has only one - the Moon, but Jupiter has 69 of them. Venus and Mercury have no satellites. Claims about their discovery appear from time to time, but all of them are soon refuted.
Jupiter's moon Ganymede is considered the largest in the solar system. It consists of silicates and ice, and reaches a diameter of 5,268 kilometers. It takes him 7 days and 3 hours to complete a revolution around Jupiter.
Mars has two “fellow travelers” with the impressive names Deimos and Phobos, which are translated from Greek as “horror” and “fear”. They have a shape close to a triaxial ellipsoid (the length of the semi-axes is not the same). Scientists say that the speed of Phobos is gradually decreasing, and it is approaching the planet. One day it will simply fall to Mars or collapse, forming a planetary ring.
Moon
The only natural satellite of the earth is the Moon. This is the closest and most studied celestial body by us outside of planet Earth. It has a core, lower, middle, upper mantle and crust. The Moon also has an atmosphere.
The satellite's crust consists of regolith - residual soil made of dust and rocky fragments of meteorites. The surface of the Moon is covered with mountains, furrows, ridges, as well as seas (large lowlands covered with solidified lava). Its atmosphere is very rarefied, which is why the sky above it is always black and starry.
The movement of the Moon around the Earth is complex. It is influenced not only by the gravity of our planet, but also by its oblate shape, as well as the gravity of the Sun, which attracts the Moon more strongly. Its complete circulation takes 27.3 days. Its orbit is in the ecliptic plane, while most other satellites are located in the equator.
The moon also rotates around its own axis. However, this movement is synchronized in such a way that it always faces the same side towards the Earth. The same phenomenon is observed in Pluto and its satellite Charon.
Artificial satellites
Artificial satellites are devices created by man and sent into near-planetary orbit. Inside they contain various instruments necessary for research.
As a rule, they are unmanned and controlled from earthly space stations. To launch them into space, special manned vehicles are used. Satellites are:
- research - for studying space and celestial bodies;
- navigation - to determine the location of Earth objects, determine the speed and direction of the signal receiver (GPS, Glonas);
- communications satellites - transmit radio signals between distant points on Earth;
- meteorological - receives data on the state of the atmosphere for weather forecasting.
The first artificial Earth satellite was launched during the Cold War in 1957. It was sent from the USSR and was called Sputnik 1. A year later, the United States released Explorer 1. Only a few years later they were followed by Great Britain, Canada, Italy, France, Australia and many other countries.
In our VK group (vk.com/posterspbru) one of the users left the following playfully sarcastic comment:
- Monya, where are you looking?
- To the stars. You won’t believe it, there are 8000 satellites there!
- So, did it become easier to breathe?
He gave us the idea for this article.
Perhaps Monya’s friend is right - in the literal sense of the word, satellites do not help people breathe. Although this is a controversial issue, because satellites can save people from situations in which people could suffocate. Probably many of us rarely think about how much our companions influence our lives.
These are some of the applications that satellites provide us.
1. Satellites send television signals to homes, but they are also the basis for cable and network TV. In other words, no satellites - no news, no broadcasts of sports matches, no Olympics in live and so on. Satellites transmit signals from central station, which generates programs for smaller stations that transmit signals locally. All direct broadcasts are possible thanks to satellites.
2. Satellites provide telephone communications on airplanes and are often the only link telephone communication for many rural regions and areas where telephone lines damaged as a result of natural disasters. Satellites also provide the primary timing source for cell phones and pagers. In 1998, a satellite failure demonstrated this dependence - 80% of pagers in the United States were temporarily silenced, National Public Radio was unable to distribute its broadcasts to affiliates and transmitted only through its website, and the CBS Evening News video was frozen and broadcast only audio.
3. Satellite navigation systems allow any user to navigate the terrain. GPS navigators are part modern world, regardless of whether they are used in private cars or for commercial or military purposes for navigation on land, sea or in the air. And by the way, GPS navigation plays a decisive role in many situations, such as when a ship is heading towards a harbor in bad weather.
4. Satellites connect companies with suppliers, are the basis for international video conferencing, and provide instant authorization credit card and conducting banking operations. Without a satellite in orbit, you will not be able to pay for goods in a hypermarket with your bank card.
5. Satellites provide meteorologists with weather data, with which they monitor not only whether it will be cloudy or sunny today, but also volcanic eruptions, hurricanes, gas leaks, and the like. Returning to the question about Monet and his friend, in some cases, satellites will help a person breathe, simply because they will warn him that a cloud of toxic gases is moving towards the place where he is. Or a satellite can rescue him at sea or on land by transmitting a beacon signal to rescue services.
Satellites are one of the main sources of data for climate change research. Satellites monitor ocean temperatures and currents. They can indicate air pollution, help organize rescue operations in disaster areas, help locate people in remote regions, transmit distress signals, etc.
6. The satellite can be detected The groundwater and mineral springs, monitor the transfer of nutrients and pollutants from land to water sources, measure land and water temperatures, measure algae growth in the seas and topsoil erosion on land. They can effectively monitor large-scale infrastructure, such as fuel pipelines, which need to be checked for leaks using satellites rather than manual labor (which would take many hours). Satellite images help various industries and even you can use Google Earth because of satellites.
Satellites provide great importance on developing countries, as they provide their populations in remote regions with access to data, educational information, medical information, etc. A person can receive the correct treatment only because his doctor has consulted with a more experienced colleague.
7. Space research is impossible without satellites. Telescope satellites play a critical role in understanding many cosmic phenomena.
Man-made satellites orbiting the Earth greatly influence our modern lives, although many do not realize it. To some extent, satellites help us breathe freely by providing us with data, timely assistance, and opportunities. Satellites make life safer, provide many modern conveniences, and also help broadcast entertainment and study the Earth and space.
Why, in order to transmit, for example, a television signal from New York to Moscow, is it necessary to launch some kind of apparatus far into space? The answer to this question is very simple: the Earth is spherical. Radio waves, which carry sound, images, and even computer data as electromagnetic waves, travel in a straight line. They cannot go around the Earth and cannot pass through its thickness. No matter where on Earth we send radio waves, they will inevitably go away from our planet, into space. True, part of the radio waves is reflected from the ionosphere - a special layer surrounding the Earth, as if from a mirror. It is reflected and again falls on the surface of the planet, many hundreds and thousands of kilometers from the transmitter. Long-distance radio communication is based on this phenomenon. That is why, with the help of a regular receiver, we can hear radio broadcasts from America or China.
But the problem is that with the help of such waves (they are called short, medium and long) it is impossible to transmit either a television image or high quality sound, nor a large amount of data. For transmission TV signal or high-quality music requires special radio waves with high frequency hesitation. They are called ultrashort. Ultrashort waves are not reflected from the ionosphere and freely go into space. How can we make sure that television images on ultrashort waves can be transmitted over long distances? Right! We need to catch waves in space and redirect them back to Earth. To where the receiver is located. That's what communications satellites are for. To put it simply, a communications satellite is a mirror for radio waves suspended in space. The satellite hangs so high that for it, cities located far from each other, for example, London and Istanbul, are “visible” at a glance. Radio waves can travel freely from the satellite to both cities without encountering any obstacles. And the waves also travel freely to the satellite from these capitals (and from many other places on Earth). The satellite helps the radio signal "jump" over the curvature globe.
In some ways, a communications satellite is similar to tall television towers. After all, the higher the tower, the further the radio signal can be transmitted. If the top of the TV tower is within line of sight, you can receive TV shows from it on your TV. But as soon as you drive further, the tower will disappear behind the horizon (that is, behind the curve of the Earth). Now the radio waves will not reach your TV. The satellite is tens of thousands of kilometers higher than the tallest tower. Therefore, it can simultaneously transmit its waves to a huge part of the globe.
However, there is a significant difference between satellite and tower. If the television tower stands in one place, then the satellite must fly at enormous speed (more than 8 kilometers per second!) around the Earth. Otherwise he will just fall. These are the laws of physics. How can we make sure that, like the top of a TV tower, it is always at the same point? Satellites observing the earth's surface or orbiting spacecraft do not fly very high - approximately at an altitude of 200 - 300 kilometers. On a good clear night they can even be seen from Earth. A bright point appeared above the horizon, flew across the sky and after a few minutes disappeared again behind the horizon. And although the point on Earth where the observer stands, as well as the satellite, rotate around the earth’s axis, the spacecraft overtakes the earth’s surface. He flies faster than the Earth rotates.
In order for the satellite to be constantly at the same point in the sky, it must be launched to a very high altitude. Then the orbit - the path that it will describe around our planet - will turn out to be very long. The satellite's orbital time and the orbital time of any point on the earth's surface around the planet's axis will become the same. Speaking scientific language, the angular velocity of the satellite and the surface of the planet will be equal.
This can be understood very clearly simple example. If you attach, for example, two plasticine balls to a rotating wheel - one on the outside of the wheel, the other on the inside, closer to the axis, then you will notice that the ball at the rim is carried with high speed, and the one near the center barely moves. However, relative to each other they are motionless and are on the same line. Angular velocity they have the same one. The ball at the axis is the surface of the Earth. The ball on the outside of the wheel is a communications satellite rotating in orbit.
An orbit that allows a satellite to hang motionless above the Earth's surface is called geostationary. It has the shape of a circle and passes approximately above the earth's equator - the line separating the Northern Hemisphere from the Southern. It is from such a satellite, located 35 - 40 thousand kilometers away, that we receive television programs on the “antennas” that little by little began to grow in homes in our country.