What are satellites for?

Who among us did not shout joyfully, looking into the deep starry sky: - Look, look, the satellite is flying! And this satellite was not at all associated with anything other than space.
But now - a completely different story! Satellites are communications, television, determination of coordinates, security, and the Internet. And many more things people will come up with for space technologists to serve for the benefit of man.
And we will tell you why and what are the most popular ways of using satellite systems today.

Why sometimes only satellite technology can be the only development option?
When installing land lines, wires are used - fiber optic or copper, or when wireless technology - cellular networks or radio internet. All these rather costly work always have significant disadvantages:

limiting the coverage of the territory. Any transmitter or receiver of a signal has a certain area of \u200b\u200bwork, which depends on the power and terrain of the area;
issues of network modernization always relate to technical capabilities and the feasibility of spending financial resources;
it is often impossible to quickly dismantle equipment and deploy a station to a new location.

And in some cases, the most justified in a technical and financial sense to ensure reliable and high-quality communication is the use of satellite systems.

Satellites will always find us

Without satellite technology, we would never be able to find each other on our large planet.
The global coordinate system allows you to accurately determine the location of objects (longitude, latitude, and even altitude above sea level), as well as the direction and speed of this object.
The well-known American system GPS (Global Positioning System) includes 24 artificial satellites, a wide network of ground stations that have unlimited connectivity to user terminals.
GPS - the system works continuously. Anyone on the planet can use it, you just need to purchase a GPS navigator. Manufacturers offer portable, automotive, aviation, marine models. Search work and rescue operations in no country in the world are complete without gPS assistance.

Not so long ago, Russia deployed its GLONASS navigation system, similar to the American one, and with the same level of positioning accuracy.
Both systems are completely available and free.

Satellites guard us

This is especially true in the automotive industry. The main security system is successfully combined with channels satellite communications, GPS and traditional radar methods.
How do satellite security systems work?
The central unit with security sensors is discreetly installed on the car. In the event of an emergency, the signal from the central unit is transmitted via communication channels to the owner or dispatcher. GPS system helps to track route, location, driving mode in real time.

Satellites entertain us

The most relevant and well-known topic is satellite TV. But we are already so used to the plates in our houses that we practically do not notice it. But only three devices: an antenna, a receiver, a converter give us extraordinary pleasure from watching our favorite TV programs.
The difference from a traditional television antenna is that instead of a tower, a satellite appears and transmits digital signal... This results in a large selection of channels and image quality.

Satellites connect us with friends

The most widespread and well-known global satellite communication systems (GSSS): Globalstar, Inmarsat, Iridium, Thuraya. At the very beginning of their creation, it was assumed that these systems organize a mobile and fixed telephony where there are no communication lines. In the further development, new opportunities appeared: access to the Internet, transfer of information in various formats. And GSSS have become multi-service.
If you describe the operation of these systems in a nutshell, it will turn out like this.
The satellite receives the subscriber's signal and transmits it to the nearest station on Earth. The station determines the signal, selects a route and sends it over terrestrial networks or satellite channel to the point of reception.
The difference between global satellite communication systems in the cost of traffic, the size and cost of subscriber terminals, coverage areas, as well as technical features the concept of the system itself.

Satellites help us live comfortably

The Very Small Aperture Terminal - VSAT satellite system is actively developing. This system - as a basis for the constructor: you can add equipment and access the Internet, other equipment - and have already been combined local area networks users in different territories. And you can also - collect data, reserve communication channels, manage various production processes, organize remote video and audio conferencing.
Such a system is easy to deploy and get started. The quality of communication, ease of content and use have already been appreciated by financial institutions, retail chains, and large industrial enterprises.

A VSAT-based network consists of a central control station (NCC), subscriber terminals and a satellite relay.
With further development, all systems will inevitably become more accessible, cheaper, more convenient and easier to manage and understand the ongoing processes of assimilation of our everyday life with satellite technologies.

Now, dreamily looking at the night sky and seeing a moving star, you will think that they, satellites, greatly facilitate and diversify life. And that is great.

Why sometimes only satellite technology can be the only development option?
When installing land lines, wires are used - fiber optic or copper, or with wireless technology - cellular networks or radio internet.

All these rather costly work always have significant disadvantages:

Territory coverage limitation. Any transmitter or receiver of a signal has a certain area of \u200b\u200boperation, which depends on the power and terrain of the area;
issues of network modernization always relate to technical capabilities and the feasibility of spending financial resources;
it is often impossible to quickly dismantle equipment and deploy a station to a new location.

And in some cases, the most justified in a technical and financial sense to ensure reliable and high-quality communications is the use of satellite systems.

Satellites will always find us

Without satellite technology, we would never be able to find each other on our large planet.
The global coordinate system allows you to accurately determine the location of objects (longitude, latitude, and even height above sea level), as well as the direction and speed of this object.
The well-known American GPS (Global Positioning System) system includes 24 artificial satellites, a wide network of ground stations that have unlimited connectivity to user terminals.
GPS - the system works continuously. Any person on the planet can use it, you just need to purchase a GPS navigator. Manufacturers offer portable, automotive, aviation, marine models. Search work and rescue operations in no country in the world are complete without the help of GPS.

Satellites guard us

This is especially true in the automotive industry. The main security system is successfully combined with satellite communication channels, GPS system and traditional radar methods.

How do satellite security systems work?

The central unit with security sensors is discreetly installed on the car. In the event of an emergency, the signal from the central unit is transmitted via communication channels to the owner or dispatcher. GPS system helps to track route, location, driving mode in real time.
Satellites entertain us
The most relevant and well-known topic is satellite TV. But we are already so used to the plates in our houses that we practically do not notice it. But only three devices: an antenna, a receiver, a converter give us extraordinary pleasure from watching our favorite TV programs.
Difference from traditional television antenna in fact, instead of a tower, a satellite acts and transmits a digital signal. This results in a large selection of channels and image quality.

Satellites connect us with friends

The most common and well-known global satellite communication systems (GSSS): Globalstar, Inmarsat, Iridium, Thuraya. At the very beginning of their creation, it was assumed that these systems organize mobile and fixed telephony where there are no communication lines. In the further development, new opportunities appeared: Internet access, information transfer in various formats. And GSSS have become multi-service.
If you describe the operation of these systems in a nutshell, it will turn out like this.
The satellite receives the subscriber's signal and transmits it to the nearest station on Earth. The station determines the signal, selects a route and sends it over terrestrial networks or satellite channel to the point of reception.
The difference between global satellite communication systems is in the cost of traffic, the size and cost of subscriber terminals, coverage areas, as well as in the technical features of the concept of the system itself.

Satellites help us live comfortably

The satellite system is actively developing Very Small Aperture Terminal - VSAT... This system is like the basis for the constructor: you can add equipment and get access to the Internet, other equipment - and the local networks of users in different territories are already united. And you can also - collect data, reserve communication channels, manage various production processes, organize remote video and audio conferencing.
Such a system is easy to deploy and get started. The quality of communication, ease of content and use have already been appreciated by financial institutions, retail chains, and large industrial enterprises.

Now, dreamily looking at the night sky and seeing a moving star, you will think that they, satellites, greatly facilitate and diversify life. And that is great.

On the outside of Sputnik, four whip antennas were transmitting at shortwave frequencies above and below the current standard (27 MHz). Tracking stations on Earth picked up the radio signal and confirmed that the tiny satellite survived the launch and successfully entered a course around our planet. A month later, the Soviet Union launched Sputnik 2 into orbit. Inside the capsule was Laika the dog.

In December 1957, desperate to keep up with their Cold War opponents, American scientists attempted to put a satellite into orbit alongside the planet Vanguard. Unfortunately, the rocket crashed and burned out during the takeoff stage. Shortly thereafter, on January 31, 1958, the United States repeated the success of the USSR by adopting Wernher von Braun's plan to launch the Explorer-1 satellite carrying the U.S. Redstone. Explorer-1 carried cosmic ray detection tools and discovered in an experiment by James Van Allen of the University of Iowa that there were far fewer cosmic rays than expected. This led to the discovery of two toroidal zones (ultimately named after Van Allen) filled with charged particles trapped in the Earth's magnetic field.

Encouraged by these successes, several companies began developing and launching satellites in the 1960s. One of them was Hughes Aircraft, along with star engineer Harold Rosen. Rosen led the team that implemented Clark's idea of \u200b\u200ba communications satellite orbiting the Earth in such a way that it could reflect radio waves from one place to another. In 1961, NASA contracted Hughes to build the Syncom series of satellites (synchronous communications). In July 1963, Rosen and his colleagues saw Syncom-2 take off into space and enter a rough geosynchronous orbit. President Kennedy used new systemto speak with the Prime Minister of Nigeria in Africa. Soon, Syncom-3 took off, which could actually broadcast a television signal.

The era of satellites has begun.

What's the difference between satellite and space debris?

Technically, a satellite is any object that orbits a planet or lesser celestial body. Astronomers classify moons as natural satellites, and over the years they have compiled a list of hundreds of such objects orbiting the planets and dwarf planets of our Solar system... For example, 67 moons of Jupiter were counted. And still.

Man-made objects such as Sputnik and Explorer can also be classified as satellites because, like moons, they revolve around the planet. Unfortunately, human activity has resulted in a huge amount of debris in Earth's orbit. All these pieces and debris behave like large rockets - they revolve around the planet at high speed in a circular or elliptical path. In the strict interpretation of the definition, each such object can be defined as a satellite. But astronomers, as a rule, consider as satellites those objects that perform useful function... Debris and other debris fall into the orbital debris category.

Orbital debris comes from many sources:

The rocket explosion that produces the most junk.
The astronaut relaxed his hand - if the astronaut repairs something in space and loses the wrench, he is lost forever. The key goes into orbit and flies at a speed of about 10 km / s. If it hits a person or a satellite, the results can be disastrous. Large objects like the ISS are a big target for space debris.
Discarded items. Parts of launch containers, camera lens caps and so on.

NASA has launched a special satellite called LDEF to study the long-term effects of collisions with space debris. Over six years, the satellite's instruments have recorded about 20,000 collisions, some of which were caused by micrometeorites and others by orbital debris. NASA scientists continue to analyze LDEF data. But in Japan there is already a giant net for catching space debris.

What's inside an ordinary satellite?

Satellites come in many shapes and sizes and perform many different functions, but they are all basically the same. They all have a metal or composite frame and body, which English-speaking engineers call a bus, and Russians call a space platform. The space platform puts everything together and provides enough measures for the tools to survive launch.

All satellites have a power source (usually solar panels) and batteries. Arrays of solar cells allow you to charge batteries. Newer satellites include fuel cells. The energy of the satellites is very expensive and extremely limited. Nuclear batteries are commonly used to send space probes to other planets.

All satellites have an on-board computer for control and monitoring different systems... They all have a radio and antenna. At a minimum, most satellites have a radio transmitter and a radio receiver, so the ground crew can query and monitor the satellite's status. Many satellites allow a lot of different things, from changing orbits to reprogramming computer system.

As you might expect, putting all these systems together is not an easy task. It takes years. It all starts with defining the purpose of the mission. Defining its parameters allows engineers to assemble the right tools and install them in the correct order. Once the specification is approved (and budget), the satellite assembly begins. It takes place in a clean room, in a sterile environment, which maintains the desired temperature and humidity and protects the satellite during development and assembly.

Artificial satellites are usually custom made. Some companies have developed modular satellites, that is, structures that can be assembled to fit additional elements to specification. For example, Boeing 601 satellites had two base modules - a chassis for transporting the propulsion subsystem, electronics and batteries; and a set of honeycomb shelves for storing equipment. This modularity allows engineers to assemble satellites from a blank, not from scratch.

How are satellites launched into orbit?

Today, all satellites are being launched into orbit on a rocket. Many transport them in the cargo department.

Most satellite launches launch a rocket straight upward, allowing it to navigate faster through the thick atmosphere and minimize fuel consumption. After the rocket takes off, the rocket's control mechanism uses the inertial guidance system to calculate the necessary adjustments to the rocket nozzle to achieve the desired tilt.

After the rocket exits into thin air, at an altitude of about 193 kilometers, the navigation system releases small rackets, which is enough to flip the rocket into a horizontal position. Then a satellite is released. Small rockets are fired again and provide the difference in distance between the rocket and the satellite.

Orbital speed and altitude

The rocket must pick up a speed of 40 320 kilometers per hour to completely escape from Earth's gravity and fly into space. The space velocity is much greater than the satellite needs in orbit. They do not avoid Earth's gravity, but are in a state of balance. Orbital speed is the speed required to maintain a balance between gravitational attraction and the inertial motion of the satellite. This is approximately 27,359 kilometers per hour at an altitude of 242 kilometers. Without gravity, inertia would carry the satellite into space. Even with gravity, if the satellite moves too fast, it will be blown into space. If the satellite moves too slowly, gravity will pull it back towards Earth.

The orbital speed of a satellite depends on its height above the Earth. The closer to Earth, the faster the speed. At an altitude of 200 kilometers, the orbital speed is 27,400 kilometers per hour. To maintain its orbit at an altitude of 35,786 kilometers, the satellite must rotate at a speed of 11,300 kilometers per hour. This orbital speed allows the satellite to fly once every 24 hours. Since the Earth also rotates 24 hours, a satellite at 35,786 kilometers is in a fixed position relative to the Earth's surface. This position is called geostationary. Geostationary orbit is ideal for weather and communication satellites.

In general, the higher the orbit, the longer the satellite can stay in it. At low altitude, the satellite is in the earth's atmosphere, which creates drag. At high altitude, there is practically no resistance, and a satellite, like the moon, can be in orbit for centuries.

Types of satellites

On earth, all satellites look similar - shiny boxes or cylinders decorated with wings from solar panels... But in space, these clumsy machines behave very differently depending on flight path, altitude and orientation. As a result, satellites are difficult to classify. One approach is to determine the orbit of the spacecraft relative to the planet (usually the Earth). Recall that there are two main orbits: circular and elliptical. Some satellites start out in an ellipse and then enter a circular orbit. Others follow an elliptical path known as the Lightning orbit. These objects, as a rule, circle from north to south through the poles of the Earth and complete a full circle in 12 hours.

Polar-orbiting satellites also pass through the poles with each revolution, although their orbits are less elliptical. The polar orbits remain fixed in space while the Earth rotates. As a result, most of the Earth passes under a satellite in polar orbit. Because polar orbits provide excellent coverage of the planet, they are used for mapping and photography. Forecasters also rely on a global network of polar satellites that orbit our balloon in 12 hours.

You can also classify satellites by their height above the earth's surface. Based on this schema, there are three categories:

Low Earth Orbit (LEO) - LEO satellites cover an area of \u200b\u200bspace from 180 to 2000 kilometers above the Earth. Satellites that move close to the Earth's surface are ideal for observing, military, and weather information gathering.
Medium Earth Orbit (MEO) - These satellites fly from 2,000 to 36,000 km above the Earth. GPS navigation satellites work well at this altitude. The approximate orbital speed is 13,900 km / h.
Geostationary (geosynchronous) orbit - geostationary satellites orbit around the Earth at an altitude exceeding 36,000 km and at the same rotational speed as the planet. Therefore, satellites in this orbit are always positioned to the same place on Earth. Many geostationary satellites fly around the equator, which has created a lot of "traffic jams" in this region of space. Several hundred television, communications, and weather satellites use geostationary orbit.

Finally, one can think of satellites in the sense where they "search". Most objects sent into space over the past few decades look at the Earth. These satellites have cameras and equipment that can see our world in different wavelengths of light, allowing you to enjoy the spectacular ultraviolet and infrared colors of our planet. Fewer satellites turn their gaze to space, where they observe stars, planets and galaxies, as well as scan objects like asteroids and comets that may collide with Earth.

Notable satellites

Until recently, satellites remained exotic and top-secret devices that were used primarily for military purposes for navigation and espionage. Now they have become an integral part of our daily life. Thanks to them, we find out the weather forecast (although forecasters, oh, how often they are mistaken). We watch TV and work with the Internet also thanks to satellites. The GPS in our cars and smartphones allows you to get to the right place. Is it worth talking about the invaluable contribution of the Hubble telescope and the work of astronauts on the ISS?

However, there are real heroes of the orbit. Let's get to know them.

Landsat satellites have been photographing the Earth since the early 1970s, and they hold the record for observing Earth's surface. Landsat-1, known at the time as ERTS (Earth Resources Technology Satellite), was launched on July 23, 1972. It carried two main instruments: a camera and a multispectral scanner built by the Hughes Aircraft Company and capable of recording data in green, red, and two infrared spectra. The satellite made such gorgeous images and was considered so successful that a whole series followed. NASA launched the last Landsat-8 in February 2013. This craft flew two Earth-observing sensors, the Operational Land Imager and the Thermal Infrared Sensor, collecting multispectral images of coastal regions, polar ice, islands and continents.
Geostationary Operational Environmental Satellites (GOES) orbit the Earth in geostationary orbit, each responsible for a fixed portion of the globe. This allows satellites to closely observe the atmosphere and detect changes in weather conditions that can lead to tornadoes, hurricanes, floods and thunderstorms. Satellites are also used to estimate the amount of precipitation and snow accumulation, measure the extent of snow cover and track the movement of sea and lake ice. Since 1974, 15 GOES satellites have been launched into orbit, but at the same time only two satellites GOES "West" and GOES "East" are observing the weather.
Jason-1 and Jason-2 have played a key role in the long-term analysis of Earth's oceans. NASA launched Jason-1 in December 2001 to replace the NASA / CNES Topex / Poseidon satellite, which has been operating on Earth since 1992. For nearly thirteen years, Jason-1 has measured sea level, wind speed and wave height in over 95% of Earth's ice-free oceans. NASA officially retired Jason-1 on July 3, 2013. In 2008, Jason-2 entered orbit. It carried high-precision instruments that made it possible to measure the distance from the satellite to the ocean surface with an accuracy of several centimeters. This data, in addition to being of value to oceanographers, provides an extensive insight into the behavior of global climate patterns.

How much do satellites cost?

After Sputnik and Explorer, satellites have become larger and more complex. Take TerreStar-1, a commercial satellite that was supposed to provide mobile data transmission in North America for smartphones and similar devices. Launched in 2009, the TerreStar-1 weighed 6,910 kilograms. And when fully deployed, it revealed an 18-meter antenna and massive solar panels with a 32-meter wingspan.

Building such a complex machine requires a ton of resources, so historically only government departments and corporations with deep pockets could enter the satellite business. Much of the cost of a satellite lies in hardware - transponders, computers, and cameras. A typical meteorological satellite costs about $ 290 million. The spy satellite will cost $ 100 million more. Add to this the cost of maintaining and repairing satellites. Companies have to pay for satellite bandwidth in the same way that phone owners pay for cellular communication... Sometimes it costs more than $ 1.5 million a year.

Others important factor is the startup cost. Launching a single satellite into space can cost anywhere from $ 10 million to $ 400 million, depending on the vehicle. The Pegasus XL rocket can lift 443 kilograms into low-earth orbit for $ 13.5 million. Launching a heavy satellite will require more lift. The Ariane 5G rocket could launch an 18,000-kilogram satellite into low orbit for $ 165 million.

Despite the costs and risks associated with building, launching and operating satellites, some companies have managed to build an entire business out of it. Take Boeing, for example. In 2012, the company delivered about 10 satellites into space and received orders for more than seven years, generating nearly $ 32 billion in revenue.

The future of satellites

Almost fifty years after the launch of Sputnik, satellites, like budgets, are growing and getting stronger. The United States, for example, has spent nearly $ 200 billion since the beginning of the military satellite program and now, despite all this, has a fleet of aging vehicles awaiting replacement. Many experts fear that the construction and deployment of large satellites simply cannot exist on taxpayer money. The solution that could turn everything upside down remains private companies like SpaceX, and others that clearly will not suffer bureaucratic stagnation like NASA, NRO and NOAA.

Another solution is to reduce the size and complexity of the satellites. Scientists from Caltech and Stanford University have been working on a new type of satellite, CubeSat, since 1999, based on building blocks with a side of 10 centimeters. Each cube contains ready-made components and can be combined with other cubes to increase efficiency and reduce load. By standardizing design and reducing the cost of building each satellite from scratch, a single CubeSat can cost as little as $ 100,000.

In April 2013 NASA decided to test this simple principle and three CubeSats powered by commercial smartphones. The goal was to put the microsatellites into orbit for a short time and take some pictures with phones. The agency now plans to deploy an extensive network of such satellites.

Whether large or small, satellites of the future must be able to communicate efficiently with ground stations. Historically, NASA has relied on radio frequency communications, but RF has reached its limit as the demand for more power has arisen. To overcome this obstacle, NASA scientists are developing a two-way communication system based on lasers instead of radio waves. On October 18, 2013, scientists first launched a laser beam to transmit data from the Moon to Earth (at a distance of 384,633 kilometers) and achieved a record transfer rate of 622 megabits per second.

Comparatively small cosmic bodies that revolve around larger host planets are called natural satellites. In part, a whole science is devoted to them - planetology.

In the 70s, astronomers assumed that Mercury had several celestial bodies depending on it, since they caught ultraviolet radiation around it. Later it turned out that the light belonged to a distant star.

Modern equipment allows for a more detailed study of the planet closest to the Sun. Today, all planetary scientists in unison insist that it has no satellites.

Satellites of the planet Venus

Venus is called similar to Earth, since they have the same composition. But if we talk about natural space objects, then the planet named after the goddess of love is close to Mercury. These two planets of the solar system are unique in that they are completely alone.

Astrologers believe that previously Venus could have seen such, but to date, none have been found.

How many natural satellites does the Earth have?

Our native Earth has many satellites, but only one natural one, which every person knows about from infancy, is the Moon.

The size of the Moon exceeds a quarter of the Earth's diameter and is 3475 km. She is the only celestial body with such large dimensions relative to the "owner".

Surprisingly, its mass is small - 7.35 × 10²² kg, which indicates a low density. Multiple craters on the surface are visible from Earth, even without any special devices.

What satellites does Mars have?

Mars is a fairly small planet that is sometimes called red because of its scarlet hue. It is given by iron oxide, which is part of it. Today Mars boasts two natural celestial objects.

Both satellites, Deimos and Phobos, were discovered by Asaf Hall in 1877. They are the smallest and darkest objects in our comic system.

Deimos is translated as the ancient Greek god who sows panic and horror. Based on observations, it is gradually moving away from Mars. Phobos, bearing the name of the god who brings fear and chaos, is the only satellite that is so close to the "master" (at a distance of 6000 km).

The surfaces of Phobos and Deimos are abundantly covered with craters, dust and various loose rocks.

Moons of Jupiter

Today the giant Jupiter has 67 satellites - more than other planets. The largest of them are considered the achievement of Galileo Galilei, since they were discovered by him in 1610.

Among the celestial bodies orbiting Jupiter, it is worth noting:

Adrasteus, with a diameter of 250 × 147 × 129 km and a mass of ~ 3.7 × 1016 kg;
Metis - dimensions 60 × 40 × 35 km, weight ~ 2 × 1015 kg;
Thebes, which has a scale of 116 × 99 × 85 and a mass of ~ 4.4 × 1017 kg;
Amalthea - 250 × 148 × 127 km, 2 1018 kg;
Io with a weight of 9 1022 kg at 3660 × 3639 × 3630 km;
Ganymede, which with a mass of 1.5 × 1023 kg had a diameter of 5263 km;
Europe, occupying 3120 km and weighing 5 · 1022 kg;
Callisto, with a diameter of 4820 km and having a mass of 1 · 1023 kg.

The first satellites were discovered in 1610, some from the 70s to the 90s, then in 2000, 2002, 2003. The last of them were discovered in 2012.

Saturn and its moons

Found 62 satellites, of which 53 have names. Most of them are composed of ice and rock, with a reflective feature.

The largest space objects of Saturn:

How many satellites does Uranus have?

At the moment, Uranus has 27 natural celestial bodies. They are named after the characters famous worksby Alexander Pope and William Shakespeare.

Names and list by quantity with description:

Moons of Neptune

The planet, whose name is consonant with the name of the great god of the seas, was discovered in 1846. She was the first to be found using mathematical calculations, and not thanks to observations. Gradually, they discovered new satellites until they counted 14.

List

Neptune's moons are named after nymphs and various sea deities from Greek mythology.

The beautiful Nereid was discovered in 1949 by Gerard Kuiper. Proteus is a non-spherical space body and is being studied in detail by planetary scientists.

Giant Triton is the iciest object in the solar system with a temperature of -240 ° C, as well as the only satellite orbiting itself in the direction opposite to the rotation of the "host".

Almost all satellites of Neptune have craters on the surface, volcanoes - both fiery and ice. They spew mixtures of methane, dust, liquid nitrogen and other substances from their depths. Therefore, a person cannot be on them without special protection.

What are "planetary satellites" and how many are there in the solar system?

Satellites are cosmic bodies that are smaller in size than the "host" planets and revolve in their orbits. The question of the origin of satellites is still open and is one of the key in modern planetology.

Today, 179 natural space objects are known, which are distributed as follows:

Venus and Mercury - 0;
Earth - 1;
Mars - 2;
Pluto - 5;
Neptune - 14;
Uranus - 27;
Saturn - 63;
Jupiter - 67.

Technologies are improving every year, finding more celestial bodies. Perhaps new satellites will be discovered soon. We just have to wait, constantly checking the news.

The largest satellite in the solar system

The largest scale in our solar system is considered to be Ganymede - the satellite of the giant Jupiter. Its diameter, according to scientists, is 5263 km. Next in size is Titan with a size of 5150 km - the "moon" of Saturn. The three leaders are closed by Callisto - Ganymede's "neighbor", with whom they share one "master". Its scale is 4800 km.

Why do planets need satellites?

Planetary scientists at all times asked the question "Why do we need satellites?" or "What impact do they have on the planets?" Based on observations and calculations, some conclusions can be drawn.

Natural satellites play an important role for "hosts". They create a certain climate on the planet. It is no less important that they serve as protection against asteroids, comets, and other dangerous celestial bodies.

Despite this significant impact, satellites are still not required for the planet. Even without their presence, life can form and be maintained on it. This conclusion was made by American scientist Jack Lissauer from NASA's Space Science Center.

Satellites and planets of the solar system

Natural satellites of planets play a colossal role in the life of these space objects. Moreover, even we humans are able to feel on our own skin the influence of the only natural satellite of our planet - the Moon.

Natural satellites of the planets of the solar system have been of great interest to astronomers for a long time. To this day, scientists are studying them. What are these space objects?

Natural satellites of planets are cosmic bodies of natural origin that revolve around planets. The most interesting for us are natural satellites of the planets of the solar system, since they are in close proximity to us.

In the solar system, only two planets do not have natural satellites... These are Venus and Mercury. Although it is assumed that earlier Mercury had natural satellites, however, this planet lost them in the process of its evolution. As for the rest of the planets of 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 space 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 talk about below.

Satellite classification

Scientists divide planetary satellites into two types: artificial and natural satellites. Artificial satellites, or, as they are also called, artificial satellites are spacecraft created by people that allow you to observe the planet around which they orbit, as well as other astronomical objects from space. Usually artificial satellites are used to observe the weather, radio broadcasting, changes in the relief of the planet's surface, as well as for military purposes.

ISS is the largest artificial Earth satellite

It should be noted that not only Earth has satellites of artificial origin, as many people believe. More than a dozen artificial satellites created by mankind revolve around the two planets closest to us - Venus and Mars. They allow you to observe climatic conditions, changes in the relief, as well as receive other relevant information regarding our space neighbors.

Ganymede is the largest satellite 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 in the solar system are asteroids that have been captured by the gravitational forces of the planets in this system. Subsequently, the asteroids took a spherical shape and as a result began to revolve around the planet that captured them as a permanent companion. There is also a theory that the natural satellites of the planets are fragments of these planets themselves, which, for one reason or another, broke away from the planet itself during its formation. By the way, according to this theory, the natural satellite of the Earth, the Moon, arose. This theory is confirmed by a chemical analysis of the composition of the moon. He showed that the chemical composition of the satellite practically does not differ 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.

Astronomers are keenly interested in the natural satellite. Most of the natural satellites of the planets in the solar system are composed primarily of ice, rock, or both, with the result that they lack an atmosphere. However, Titan has this, and it is quite dense, as well as lakes of liquid hydrocarbons.

Another natural satellite that gives scientists hope for the detection of extraterrestrial life forms is Jupiter's moon. It is believed that under the thick layer of ice that covers the satellite, there is an ocean, inside which thermal springs operate - exactly the same as on Earth. Since some deep sea life on Earth exists from 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 on the planet of the solar system on which astrophysicists first discovered active volcanoes. It is for this reason that it is of particular interest to space explorers.

Natural satellite research

Studies of natural satellites of the planets of the solar system have interested the minds of astronomers since ancient times. Since the invention of the first telescope, people have actively studied these celestial objects. A 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 foot 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 lunar surface, which caused jubilation in the hearts of the then mankind and is still considered one of the most important and significant events in space exploration.

In addition to the Moon, scientists are actively involved in the study of 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 the Earth images of several of Jupiter's largest satellites:,. In particular, thanks to these images, scientists were able to record the presence of volcanoes on the satellite Io, and the ocean on Europa.

Today, the world community of space explorers continues to actively study 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 now developing a tourist lunar rover, on which many who wish could take a walk on the moon.