The second artificial earth satellite. The second artificial satellite of the earth Who owns the satellites of the Earth

The fundamental decision to begin work on creating a satellite for the flight of a living creature was made back in 1956. Carrying out experiments for a long time required the creation of equipment that would be able to automatically maintain the necessary conditions for the life of an animal in flight, in particular, a certain temperature and humidity, provide it with the necessary amount of food and water, remove waste products, etc. The research equipment had to ensure uninterrupted automatic recording of the necessary scientific data and their transmission to Earth. It was necessary to resolve issues of special training of animals, in particular to the effects of a number of dynamic factors (noise, vibration, overload), long-term stay in a fixed position in a small cabin with specific features of nutrition, water supply, natural needs, etc. The creation and manufacture of both the satellite itself and the compartment for the animal were carried out by specialists from the Korolev OKB-1, working in contact with specialists from the 8th department of the Research Testing Institute of Aviation Medicine (NIIIIAM).

After the successful launch of the first Earth satellite on October 4, 1957, the work plan for the animal’s flight was revised. The leadership of the USSR and N.S. Khrushchev personally demanded that the success be consolidated. Under these conditions, it was decided to create a second, simplest satellite without a system for returning to Earth. This decision to launch a second artificial satellite with a dog on the fortieth anniversary of the October Revolution (November 7) was actually a death sentence for the future four-legged “cosmonaut”. It was officially accepted October 12, 1957. Due to the tight deadlines, the second simplest satellite was created without any preliminary sketch or other design - there was no time. Almost all parts were made according to sketches, assembly was carried out according to the instructions of the designers and by local adjustments. The total weight of the satellite is 508.3 kilograms. In order not to install a separate data transmission system on the satellite, it was decided not to separate the spacecraft from the central unit. Since in this case the second stage of the rocket itself enters the satellite orbit, the Tral equipment, which was installed on the carrier, was used to transmit the parameters. Thus, the second artificial satellite represented the entire second stage - the central block of the launch vehicle.

To accommodate the animal on board the satellite, a special design was developed - a sealed animal cabin (SHC). The GKZ mounted on a load frame was a cylindrical container with a diameter of 640 mm and a length of 800 mm, equipped with a removable lid with an inspection hatch. The removable cover contained hermetic connectors for entering electrical wires. The animal cabin was made of aluminum alloy. The container contained a very compact experimental animal and all the necessary equipment, which consisted of installations for air regeneration and temperature control in the cabin, a feeder with a supply of food, a sewage disposal device and a set of medical equipment.

The air regeneration installation contained a regeneration substance that absorbed carbon dioxide and water vapor and released the required amount of oxygen. The supply of regenerative substance provided the animal's oxygen needs for 7 days. Small electric motors were used to ventilate the regeneration unit. The operation of the installation was regulated by a bellows barorel, which, when the air pressure increased above 765 mm Hg. turned off the most active part of the regeneration plant. The device for regulating the air temperature included a special heat-dissipating screen, to which air removed from the animal was supplied, and a dual thermal relay, which turned on the blower fan when the air temperature in the cabin increased above +15°C.

Feeding and providing water to the animal was carried out from a metal tank with a volume of 3 liters, containing a supply of jelly-like mass, designed to fully meet the animal’s needs for water and food for seven days.

In the 8th department of NIIIAM, dogs were trained to participate in future flights. Oleg Georgievich Gazenko supervised the work on training animals and developing the necessary conditioned connections in them. Based on the predetermined dimensions of the container for the animal, small dogs weighing no more than 6000 g were selected. First, the animal was accustomed to the laboratory environment and staying in special cages. The volume of these cages gradually decreased, approaching the size of a dog cage in a pressurized satellite cabin. The duration of stay of animals in such cages in ground experiments gradually increased from several hours to 15-20 days. At the same time, the animal was accustomed to wearing special clothing, a sewage disposal device (attached to the body of a urine bag) and sensors for recording physiological functions.

During the training, careful individual adjustment of all equipment was carried out. This work was considered completed when the animal calmly tolerated a 20-day stay in a cramped cage with all the equipment and did not show any disturbances in its general condition or local injuries.

The next stage of the training was to accustom the animals to a long stay in a hermetic cabin. This cabin housed all the necessary equipment intended for the future flight of the satellite. The dogs were accustomed to the cabin environment, feeding from automatic machines, and the noise of operating units. The animal's reaction to a complex set of stimuli associated with the installation of equipment and equipment and the sealing of the cabin was suppressed. At the same time, cabin equipment and measuring equipment were tested, during which they were improved.

By the time the second manned artificial Earth satellite was ready to launch, the Institute of Aviation Medicine had fully completed the preparation and training of ten animals, which lasted a total of about a year. Of the dogs that were very similar to each other, three were selected: Albina, Laika and Mukha. There was also a fourth - male Atom, but he died during training. Albina was already an experienced “cosmonaut”, having twice been in space flight while launching geophysical rockets. The final choice was made by Vladimir Yazdovsky ten days before the launch. Two-year-old Laika was to go on a non-returnable flight, Albina was enlisted as a backup, and the dog Mukha was decided to be used as a “technological” dog for testing, with her participation, measuring equipment and equipment for the GKZ life support systems already at the cosmodrome. All animals were previously operated on by V.I. Yazdovsky. The common carotid artery was exposed into a skin flap to measure arterial blood pressure, and sensors were implanted on the chest to record ECG and chest respiratory rate.

Dog training continued upon arrival at the cosmodrome. Right up until the launch, Laika was placed in a container for several hours every day. The dog became completely accustomed to the training conditions, sat calmly, allowed indicators of physiological functions to be recorded, and willingly accepted food. A few days before the flight, a dress rehearsal for the flight was held. The dog Mukha was put in the GKZh and left in the steppe. On the third day, it was decided to interrupt her “flight”. When the cabin was opened, the dog turned out to be alive, but exhausted, since it had not eaten anything for three days. The food used was the jelly-like consistency of the diet, which was proposed by the institute’s staff. This resolved the issues of providing the animal with the necessary amount of water in zero gravity.

On October 31 at 10 am they began preparing Laika for the flight. At about one o'clock in the morning on November 1, the GKZh with Laika was installed on the rocket. The launch of the Sputnik-2 spacecraft was carried out November 3, 1957 from the Baikonur Cosmodrome. At takeoff, Laika’s pulse reached 260 beats per minute (three times higher than normal). The breathing rate increased 4 - 5 times. In conditions of weightlessness, physiological processes became normal. Unfortunately, the heat removal system from the animal’s cabin did not work effectively enough, and excessive heat was generated by the regeneration system. Among other things, there was also a “leakage” of heat from the undocked last stage of the rocket. The air temperature in the biocabin during the first hours of the flight ranged from +10 to +38°C, and then by the 8th hour of the flight it increased to +42°C.

But it was not possible to receive information about Laika’s condition within a week, as originally planned. The clock mechanism failed. Commands to turn on the telemetry transmitter were issued not at those moments when the spacecraft passed over the territory of the USSR, but somewhere beyond its borders. Therefore, the doctors had no information about Laika’s well-being within 24 hours. The death of the animal on the second artificial satellite of the Earth occurred from overheating 5 - 6 hours after the start of intense overheating. This assumption was made on the basis of specially conducted analytical experiments on dogs in laboratory conditions in 1958, during which dogs were placed in similar conditions. All dogs died from overheating. The satellite with the dead dog was in orbit until mid-April 1958, after which it entered the dense layers of the atmosphere and burned up.

An Earth satellite is any object that moves along a curved path around a planet. The Moon is the original, natural satellite of the Earth, and there are many artificial satellites, usually in close orbit to the Earth. The path followed by a satellite is an orbit, which sometimes takes the shape of a circle.

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To understand why satellites move the way they do, we have to go back to our friend Newton. exists between any two objects in the Universe. If not for this force, a satellite moving near the planet would continue to move at the same speed and in the same direction - in a straight line. However, this rectilinear inertial path of the satellite is balanced by a strong gravitational attraction directed towards the center of the planet.

Orbits of artificial earth satellites

Sometimes a satellite's orbit looks like an ellipse, a squashed circle that moves around two points known as foci. The same basic laws of motion apply, except that the planet is at one of the foci. As a result, the net force applied to the satellite is not uniform throughout the orbit, and the satellite's speed is constantly changing. It moves fastest when it is closest to Earth - a point known as perigee - and slowest when it is furthest from Earth - a point known as apogee.

There are many different satellite orbits of the Earth. The ones that receive the most attention are geostationary orbits because they are stationary over a specific point on the Earth.

The orbit chosen for an artificial satellite depends on its application. For example, live broadcast television uses the geostationary orbit. Many communications satellites also use geostationary orbit. Other satellite systems, such as satellite phones, may use low-Earth orbits.

Likewise, satellite systems used for navigation, such as Navstar or Global Positioning (GPS), occupy a relatively low Earth orbit. There are also many other types of satellites. From weather satellites to research satellites. Each will have its own orbit type depending on its application.

The actual Earth satellite orbit chosen will depend on factors including its function, and the area in which it is to serve. In some cases, the Earth satellite's orbit can be as large as 100 miles (160 km) for a LEO low earth orbit, while others can reach over 22,000 miles (36,000 km) as in the case of a GEO low earth orbit.

The first artificial earth satellite

The first artificial earth satellite was launched on October 4, 1957 by the Soviet Union and was the first artificial satellite in history.

Sputnik 1 was the first of several satellites launched by the Soviet Union in the Sputnik program, most of which were successful. Satellite 2 followed the second satellite in orbit and also the first to carry an animal on board, a female dog named Laika. Sputnik 3 suffered the first failure.

The first earth satellite had an approximate mass of 83 kg, had two radio transmitters (20.007 and 40.002 MHz) and orbited the Earth at a distance of 938 km from its apogee and 214 km at its perigee. Analysis of radio signals was used to obtain information about the concentration of electrons in the ionosphere. Temperature and pressure were encoded over the duration of the radio signals it emitted, indicating that the satellite was not perforated by a meteorite.

The first earth satellite was an aluminum sphere with a diameter of 58 cm, having four long and thin antennas ranging from 2.4 to 2.9 m in length. The antennas looked like long mustaches. The spacecraft received information about the density of the upper atmosphere and the propagation of radio waves in the ionosphere. Instruments and sources of electrical energy were housed in a capsule that also included radio transmitters operating at 20.007 and 40.002 MHz (about 15 and 7.5 m wavelength), emissions were made in alternate groups of 0.3 s duration. Ground telemetry included temperature data inside and on the surface of the sphere.

Because the sphere was filled with pressurized nitrogen, Sputnik 1 had its first opportunity to detect meteorites, although it did not. The loss of internal pressure due to penetration of the external surface was reflected in the temperature data.

Types of artificial satellites

Artificial satellites come in different types, shapes, sizes and play different roles.

• Weather satellites help meteorologists predict the weather or see what is currently happening. A good example is the Geostationary Operational Environmental Satellite (GOES). These earth satellites typically contain cameras that can return photographs of Earth's weather, either from fixed geostationary positions or from polar orbits.
• Communications satellites allow the transmission of telephone and information conversations via satellite. Typical communications satellites include Telstar and Intelsat. The most important feature of a communications satellite is the transponder, a radio receiver that picks up a conversation on one frequency and then amplifies it and retransmits it back to Earth on a different frequency. A satellite typically contains hundreds or thousands of transponders. Communication satellites are usually geosynchronous.
• Broadcast satellites transmit television signals from one point to another (similar to communication satellites).
• Scientific satellites, such as the Hubble Space Telescope, carry out all kinds of scientific missions. They look at everything from sunspots to gamma rays.
• Navigation satellites help ships and planes navigate. The most famous are the GPS NAVSTAR satellites.
• Rescue satellites respond to radio interference signals.
• Earth observation satellites checking the planet for changes in everything from temperature, forest cover, to ice cover. The most famous are the Landsat series.
• Military satellites The Earths are in orbit, but much of the actual position information remains secret. Satellites could include encrypted communications relay, nuclear monitoring, surveillance of enemy movements, early warning of missile launches, eavesdropping on terrestrial radio links, radar imaging, and photography (using essentially large telescopes that photograph militarily interesting areas).

Earth from an artificial satellite in real time

Images of the earth from an artificial satellite, broadcast in real time by NASA from the International Space Station. The images are captured by four high-resolution cameras isolated from freezing temperatures, allowing us to feel closer to space than ever before.

The experiment (HDEV) on board the ISS was activated on April 30, 2014. It is mounted on the external cargo mechanism of the European Space Agency's Columbus module. This experiment involves several high-definition video cameras that are enclosed in a housing.

Advice; put the player in HD and full screen. There are times when the screen will be black, this can be for two reasons: the station is passing through an orbital zone where it is at night, the orbit lasts approximately 90 minutes. Or the screen goes dark when the cameras change.

How many satellites are there in Earth orbit 2018?

According to the United Nations Office for Outer Space Affairs (UNOOSA) Index of Objects Launched into Outer Space, there are currently some 4,256 satellites in Earth's orbit, up 4.39% from last year.

221 satellites were launched in 2015, the second most in a single year, although it is below the record number of 240 launched in 2014. The increase in the number of satellites orbiting the Earth is less than the number launched last year because satellites have a limited lifespan. Large communications satellites last 15 years or more, while small satellites such as CubeSats can only expect a service life of 3-6 months.

How many of these Earth orbiting satellites are operational?

The Union of Scientists (UCS) is clarifying which of these orbiting satellites are working, and it's not as much as you think! There are currently only 1,419 operational Earth satellites - only about one third of the total number in orbit. This means there is a lot of useless metal around the planet! That's why there's a lot of interest from companies looking at how they capture and return space debris, using techniques like space nets, slingshots or solar sails.

What are all these satellites doing?

According to UCS, the main objectives of operational satellites are:

• Communications - 713 satellites
• Earth observation/science - 374 satellites
• Technology demonstration/development using 160 satellites
• Navigation & GPS - 105 satellites
• Space science - 67 satellites

It should be noted that some satellites have multiple purposes.

Who owns the Earth's satellites?

It is interesting to note that there are four main types of users in the UCS database, although 17% of satellites are owned by multiple users.

• 94 satellites registered by civilians: these are generally educational institutions, although there are other national organizations. 46% of these satellites have the purpose of developing technologies such as Earth and space science. Observations account for another 43%.
• 579 belong to commercial users: commercial organizations and government organizations that want to sell the data they collect. 84% of these satellites are focused on communications and global positioning services; of the remaining 12% are Earth observation satellites.
• 401 satellites are owned by government users: mainly national space organizations, but also other national and international bodies. 40% of them are communications and global positioning satellites; another 38% is focused on Earth observation. Of the remainder, the development of space science and technology accounts for 12% and 10%, respectively.
• 345 satellites belong to the military: again the focus here is communications, Earth observation and global positioning systems, with 89% of the satellites having one of these three purposes.

How many satellites do countries have?

According to UNOOSA, about 65 countries have launched satellites, although the UCS database only has 57 countries recorded using satellites, and some satellites are listed with joint/multinational operators. The biggest:

• USA with 576 satellites
• China with 181 satellites
• Russia with 140 satellites
• The UK is listed as having 41 satellites, plus participates in an additional 36 satellites operated by the European Space Agency.

Remember when you look!
Next time you look at the night sky, remember that between you and the stars there are about two million kilograms of metal surrounding the Earth!

Let us now get acquainted with the second cosmic or parabolic speed, which is understood as the speed necessary for a body to overcome gravity. If a body reaches the second cosmic velocity, then it can move away from the Earth to any arbitrarily large distance (it is assumed that no other forces will act on the body except the forces of gravity).

The easiest way to obtain the value of the second escape velocity is to use the law of conservation of energy. It is quite obvious that after the engines are turned off, the sum of the kinetic and potential energy of the rocket must remain constant. Let us assume that at the moment the engines were turned off, the rocket was at a distance R from the center of the Earth and had an initial speed V (for simplicity, let’s consider the vertical flight of the rocket). Then, as the rocket moves away from the Earth, its speed will decrease. At a certain distance r max the rocket will stop, as its speed will go to zero, and will begin to freely fall to the Earth. If at the initial moment the rocket had the greatest kinetic energy mV 2 /2, and the potential energy was equal to zero, then at the highest point, where the speed is zero, the kinetic energy goes to zero, turning entirely into potential. According to the law of conservation of energy, we find:

mV 2 /2=fmM(1/R-1/r max) or V 2 =2fM(1/R-1/r max).

Assuming r max is infinite, we find the value of the second escape velocity:

V par = 2fM/R = 2 fM/R = 2 V cr.

It turns out that it exceeds the first escape velocity by 2

once. If we remember that the acceleration of gravity g=fM/R 2, then we arrive at the formula V pairs = 2gR. To determine the second escape velocity at the Earth’s surface, you should substitute R = 6400 km into this formula, resulting in: V cr » 11.19 km/sec

Using the above formulas, you can calculate the parabolic speed at any distance from the Earth, as well as determine its value for other bodies of the solar system.

The energy integral derived above allows us to solve many problems in astronautics, for example, it allows us to make simple approximate calculations of the motion of planetary satellites, space rockets and large planets. The derived formula for parabolic speed can also be used in approximate calculations of interstellar flight. To fly to the stars, it is necessary to overcome solar gravity, i.e. To the starship

the speed at which it will move relative to the Sun in a parabolic or hyperbolic orbit must be reported. Let's call the lowest initial speed the third escape velocity. Substituting the value of the mass of the Sun instead of M into the parabolic speed formula, and instead of R the average distance from the Earth to the Sun, we find that a spacecraft starting from Earth orbit should be given a speed of about 42.2 km/sec. So, if a body is given a heliocentric speed of 42.2 km/sec, then it will leave the solar system forever, describing a parabolic orbit relative to the Sun. Let's find out what the speed relative to the Earth should be to ensure that the body moves away not only from the Earth, but also from the Sun? Sometimes they reason like this: since the average speed of the Earth relative to the Sun is 29.8 km/sec, it is necessary to impart to the spacecraft a speed of 42.2 km/sec - 29.8 km/sec, i.e. 12.4 km/sec. This is incorrect, since in this case the movement of the Earth in orbit during the removal of the spacecraft and the attraction from the Earth while the ship is in its sphere of action are not taken into account. Therefore, the third escape velocity relative to the Earth is greater than 12.4 km/sec and equal to 16.7 km/sec.

Movement of artificial earth satellites.

The motion of artificial Earth satellites is not described by Kepler’s laws, which is due to two reasons:

1) The Earth is not exactly a sphere with a uniform density distribution over its volume. Therefore, its gravitational field is not equivalent to the gravitational field of a point mass located at the geometric center of the Earth;

2) The Earth's atmosphere has a braking effect on the movement of artificial satellites, as a result of which their orbit changes its shape and size and, as a result, the satellites fall to the Earth.

Based on the deviation of the satellites’ motion from the Keplerian one, one can draw a conclusion about the shape of the Earth, the distribution of density over its volume, and the structure of the Earth’s atmosphere. Therefore, it was the study of the movement of artificial satellites that made it possible to obtain the most complete data on these issues.

If the Earth were a homogeneous ball and there was no atmosphere, then the satellite would move in orbit, the plane maintaining a constant orientation in space relative to the system of fixed stars. The orbital elements in this case are determined by Kepler's laws. Since the Earth rotates, with each subsequent revolution the satellite moves over different points on the earth's surface. Knowing the satellite's path for one revolution, it is not difficult to predict its position at all subsequent times. To do this, it is necessary to take into account that the Earth rotates from west to east at an angular speed of approximately 15 degrees per hour. Therefore, on the next revolution, the satellite crosses the same latitude to the west by as many degrees as the Earth turns to the east during the period of rotation of the satellite.

Due to the resistance of the earth's atmosphere, satellites cannot move for a long time at altitudes below 160 km. The minimum period of revolution at such an altitude in a circular orbit is approximately 88 minutes, that is, approximately 1.5 hours. During this time, the Earth rotates by 22.5 degrees. At a latitude of 50 degrees, this angle corresponds to a distance of 1400 km. Therefore, we can say that a satellite with an orbital period of 1.5 hours at a latitude of 50 degrees will be observed at each subsequent revolution approximately 1400 km further west than on the previous one.

However, such a calculation provides sufficient prediction accuracy for only a few satellite revolutions. If we are talking about a significant period of time, then we must take into account the difference between a sidereal day and 24 hours. Since the Earth makes one revolution around the Sun in 365 days, then in one day the Earth around the Sun describes an angle of approximately 1 degree (more precisely, 0.99) in the same direction in which it rotates around its axis. Therefore, in 24 hours the Earth rotates relative to the fixed stars not by 360 degrees, but by 361 and, therefore, makes one revolution not in 24 hours, but in 23 hours 56 minutes. Therefore, the satellite’s latitude path shifts westward not by 15 degrees per hour, but by 15.041 degrees.

The circular orbit of a satellite in the equatorial plane, moving along which it is always above the same point of the equator, is called geostationary. Almost half of the earth's surface can be connected to a satellite in a synchronous orbit by linearly propagating high-frequency signals or light signals. Therefore, satellites in synchronous orbits are of great importance for the communication system.

Spaceship landing

One of the most difficult problems in astronautics is landing a spacecraft or container with scientific equipment on Earth or a destination planet. The method of landing on various celestial bodies depends significantly on the presence of an atmosphere on the destination planet, on the physical properties of the surface and many other reasons. The denser the atmosphere, the easier it is to reduce the escape velocity of a ship and land it, because the planetary atmosphere can be used as a kind of air brake.

There are three ways to land spacecraft. The first method is a hard landing, which occurs without reducing the speed of the ship. Maintaining escape velocity at the moment of impact with the planet, the ship is destroyed. For example, when approaching the Moon, the speed of the ship is 2.3 - 3.3 km/sec. Creating a structure that could withstand the shock stresses that occur at these speeds is a technically insurmountable task. The same picture will be observed during a hard landing on Mercury, asteroids and other celestial bodies devoid of an atmosphere.

Another landing method is a rough landing with partial deceleration. In this option, when the rocket enters the sphere of action of the planet, the ship should be turned so that the engine nozzles are directed towards the destination planet. Then the thrust of the engines, being directed in the direction opposite to the movement of the ship, will slow down the movement. The rotation of the ship around its axis can be done using low-power engines. One possible solution to the problem is to install two engines on the sides of the ship, offset relative to each other, and the thrust forces of these engines should be directed in opposite directions. Then a pair of forces arises (two forces equal in magnitude and opposite in direction), which will turn the ship in the desired direction. Then the rocket engines are turned on, reducing the speed to a certain limit. At the moment of landing, the rocket can have a speed of several hundred meters per second so that it can withstand the impact on the surface.

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main idea

This site is dedicated to surveillance issues artificial earth satellites(further satellite ). Since the beginning of the space age (October 4, 1957, the first satellite, Sputnik 1, was launched), humanity has created a huge number of satellites that circle the Earth in all kinds of orbits. Currently, the number of such man-made objects exceeds tens of thousands. This is mainly “space debris” - fragments of artificial satellites, spent rocket stages, etc. Only a small part of them are operational satellites.
Among them there are research and meteorological satellites, communications and telecommunications satellites, and military satellites. The space around the Earth is “populated” by them from altitudes of 200-300 km and up to 40,000 km. Only some of them are accessible for observation using inexpensive optics (binoculars, telescopes, amateur telescopes).

By creating this site, the authors set themselves the goal of collecting together information about methods of observing and filming satellites, showing how to calculate the conditions for their flight over a certain area, and describing the practical aspects of the issue of observation and filming. The site presents mainly original material obtained during observations by participants in the “Cosmonautics” section of the astronomy club “hν” at the Minsk Planetarium (Minsk, Belarus).

And yet, answering the main question - “Why?”, the following must be said. Among the various hobbies that people are interested in are astronomy and astronautics. Thousands of astronomy lovers observe planets, nebulae, galaxies, variable stars, meteors and other astronomical objects, photograph them, and hold their own conferences and “master classes.” For what? It's just a hobby, one of many. A way to get away from everyday problems. Even when amateurs perform work of scientific significance, they remain amateurs who do it for their own pleasure. Astronomy and astronautics are very “technological” hobbies where you can apply your knowledge of optics, electronics, physics and other natural science disciplines. Or you don’t have to use it - and just enjoy contemplation. Things are similar with satellites. It is especially interesting to monitor those satellites, information about which is not distributed in open sources - these are military intelligence satellites of different countries. In any case, satellite observation is hunting. Often we can indicate in advance where and when the satellite will appear, but not always. And how he will “behave” is even more difficult to predict.

Thanks:

The described methods were created on the basis of observations and research in which members of the astronomy club "hν" of the Minsk Planetarium (Belarus) took part:

• Bozbey Maxim.
• Dremin Gennady.
• Kenko Zoya.
• Mechinsky Vitaly.

Members of the astronomy club "hν" also provided great assistance. Lebedeva Tatyana, Povalishev Vladimir And Tkachenko Alexey. Special thanks Alexander Lapshin(Russia), profi-s (Ukraine), Daniil Shestakov (Russia) and Anatoly Grigoriev (Russia) for assistance in creating paragraph II §1 “Satellite Photometry”, Chapter 2 and Chapter 5, and Elena (Tau, Russia) also for consultations and writing several calculation programs. The authors also thank Mikhail Abgaryan (Belarus), Yuri Goryachko (Belarus), Anatoly Grigoriev (Russia), Leonid Elenin (Russia), Victor Zhuk (Belarus), Igor Molotov (Russia), Konstantin Morozov (Belarus), Sergei Plaksa (Ukraine), Ivan Prokopyuk (Belarus) for providing illustrations for some sections of the site.

Some of the materials were received in the course of fulfilling an order from the Geographic Information Systems Unitary Enterprise of the National Academy of Sciences of Belarus. The presentation of materials is carried out on a non-profit basis in order to popularize the Belarusian space program among children and youth.

Vitaly Mechinsky, Curator of the “Cosmonautics” section of the “hν” astroclub.

Site news:

• 09/01/2013: Significantly updated subparagraph 2 "Photometry of satellites during flight" p. II §1 - ​​information has been added on two methods of photometry of satellite tracks (method of photometric track profile and method of isophote photometry).
• 09/01/2013: Subclause II §1 was updated - information on working with the "Highecl" program for calculating probable outbreaks from the GSS was added.
• 01/30/2013: Updated "Chapter 3"-- added information on working with the "MagVision" program to calculate the drop in penetration from illumination from the Sun and Moon.
• 01/22/2013: Updated Chapter 2. Added animation of satellites moving across the sky in one minute.
• 01/19/2013: Subsection updated "Visual observations of satellites" paragraph 1 "Determination of satellite orbits" §1 of Chapter 5. Added information about heating devices for electronics and optics to protect against dew, frost and excessive cooling.
• 01/19/2013: Added to "Chapter 3" information about the drop in penetration when illuminated by the Moon and twilight.
• 01/09/2013: Added sub-item "Flashes from the lidar satellite "CALIPSO" subclause “Photography of flashes”, paragraph II “Photometry of satellites” §1 of Chapter 5. Information on the features of observing flashes from the laser lidar of the satellite “CALIPSO” and the process of preparing for them are described.
• 11/05/2012: The introductory part of §2 of Chapter 5 has been updated. Information on the required minimum equipment for radio observations of satellites has been added, and a diagram of the LED signal level indicator, which is used to set the input audio signal level safe for the voice recorder, is shown.
• 11/04/2012: Sub-clause updated "Visual observations of satellites" paragraph 1 "Determination of satellite orbits" §1 of Chapter 5. Information has been added about the Brno star atlas, as well as about the red film on the LCD screens of electronic devices used in observations.
• 04/14/2012: Updated sub-item of the sub-item "Photo/video shooting of satellites" clause 1 "Determination of satellite orbits" §1 of Chapter 5. Added information about working with the "SatIR" program for identifying satellites in photographs with a wide field of view, as well as determining coordinates ends of satellite tracks on them.
• 04/13/2012: Subsection updated "Astrometry of satellites on the received images: photos and videos" subsection "Photo/video shooting of satellites" clause 1 "Determination of satellite orbits" §1 of Chapter 5. Added information about working with the "AstroTortilla" program to determine the coordinates of the center of the field of view of images of areas of the starry sky.
• 03/20/2012: Subclause 2 “Classification of satellite orbits by semimajor axis” §1 of Chapter 2 has been updated. Information has been added about the magnitude of GSS drift and orbital disturbances.
• 03/02/2012: Added sub-item "Observing and filming rocket launches at a distance" subparagraph “Photo/video shooting of satellites”, paragraph I “Determination of satellite orbits” §1 of Chapter 5. Information on the features of observing the flight of launch vehicles at the launch stage is described.
• "Converting astrometry to IOD format" subsection "Photo/video shooting of satellites" paragraph I "Determination of satellite orbits" §1 of Chapter 5. Added description of working with the program "ObsEntry for Window" for converting satellite astrometry into IOD format - an analogue of the "OBSENTRY" program, but for the OS Windows.
• 02/25/2012: Subclause updated "Sun-synchronous orbits" paragraph 1 "Classification of satellite orbits by inclination" §1 of Chapter 2. Added information on calculating the inclination value i ss of a sun-synchronous satellite orbit depending on the eccentricity and semi-major axis of the orbit.
• 09.21.2011: Subclause 2 “Photometry of satellites during a flight” has been updated, clause II “Photometry of satellites” §1 of Chapter 5. Information has been added about the synodic effect, which distorts the determination of the rotation period of satellites.
• 09.14.2011: Sub-clause updated "Calculation of orbital (Keplerian) elements of the satellite's orbit based on astrometric data. One flyby" subclause "Photo/video shooting of satellites" of paragraph I "Determination of satellite orbits" §1 of Chapter 5. Information has been added about the "SatID" program for satellite identification (using received TLE) among satellites from a third-party TLE database, and also a method for satellite identification in program "Heavensat" based on the observed flyby near the guide star.
• 09.12.2011: Updated sub-item "Calculation of orbital (Keplerian) elements of the satellite's orbit based on astrometric data. Several flights" of the sub-item "Photo/video shooting of satellites" of paragraph I "Determination of satellite orbits" §1 of Chapter 5. Added information about the TLE recalculation program -elements for the required date.
• 09/12/2011: Added sub-item "Entry of an artificial satellite into the Earth's atmosphere" subclause “Photo/video shooting of satellites”, paragraph I “Determination of satellite orbits” §1 of Chapter 5. Information on working with the “SatEvo” program for predicting the date of entry of satellites into the dense layers of the Earth’s atmosphere is described.
• "Flashes from geostationary satellites" subclause “Photography of flashes”, p. II “Photometry of satellites” §1 of Chapter 5. Information has been added about the period of visibility of GSS flashes.
• 09/08/2011: Sub-clause updated "Change in the brightness of an satellite during its flight" subparagraph 2 "Photometry of satellites during the flight" paragraph II "Photometry of satellites" §1 of Chapter 5. Added information about the form of the phase function for several examples of reflective surfaces.
• subparagraph 1 "Observation of artificial satellite flares" paragraph II "Satellite photometry" §1 of Chapter 5. Added information about the unevenness of the time scale along the image of the satellite track on the photodetector matrix.
• 09/07/2011: Sub-clause updated "Photometry of satellites during flight" p. II "Photometry of satellites" §1 of Chapter 5. Added an example of a complex light curve of the satellite "NanoSail-D" (SCN:37361) and modeling of its rotation.
• "Flashes from low-orbit satellites" subparagraph 1 “Observation of satellite flares”, paragraph II “Photometry of satellites” §1 of Chapter 5. A photograph and photometric profile of a flare from the LEO satellite “METEOR 1-29” have been added.
• 09/06/2011: Sub-clause updated "Geostationary and geosynchronous satellite orbits"§1 of Chapter 2. Added information on the classification of geostationary satellites, information on the shape of GSS trajectories.
• 09/06/2011: Sub-clause updated "Shooting the passage of satellites: equipment for shooting. Optical elements" subclause “Photo/video shooting of satellites”, paragraph I “Determination of satellite orbits” §1 of Chapter 5. Added links to reviews of domestic lenses as applied to shooting of satellites.
• 09/06/2011: Sub-clause updated "Phase angle" Section II "Satellite Photometry" §1 Chapter 5. Added animation of satellite phase changes depending on the phase angle.
• 13.07.2011: Completed completion of all chapters and sections of the site.
• 07/09/2011: Finished writing the introductory part to paragraph II "Satellite Photometry"§1 Chapter 5.
• 07/05/2011: Finished writing the introductory part to §2 "Radio observations of satellites" Chapters 5.
• 07/04/2011: Sub-clause updated "Processing observations" p. I "Reception of satellite telemetry" §2 of Chapter 5.
• 07/04/2011: Finished writing Section II "Obtaining cloud images"§2 Chapter 5.
• 07/02/2011: Finished writing Section I "Reception of satellite telemetry"§2 Chapter 5.
• 07/01/2011: Finished writing the subparagraph "Photo/video shooting of satellites" clause I §1 Chapter 5.
• 06/25/2011: Finished writing Applications.
• 06/25/2011: Finished writing the introductory part to Chapter 5: “What and how to observe?”
• 06/25/2011: Finished writing the introductory part to §1 "Optical observations" Chapters 5.
• 06/25/2011: Finished writing the introductory part to paragraph I "Determination of satellite orbits"§1 Chapter 5.
• 06/25/2011: Finished writing Chapter 4: "About Time".
• 01/25/2011: Finished writing Chapter 2: "What kind of orbits and satellites are there?".
• 01/07/2011: Finished writing Chapter 3: "Preparing for Observations".
• 01/07/2011: Finished writing Chapter 1: "How do satellites move?"

The theory of motion of satellites and other spacecraft used in remote sensing, cartography and geodesy is a complex branch of applied celestial mechanics. These spacecraft, as a rule, have low orbits with a periapsis altitude of about 250400 km. Therefore, even small changes in mass concentrations in the Earth’s body, all deviations of the Earth’s shape from spherical cause disturbances in the orbital elements. In addition, the spacecraft moves in fairly dense layers of the atmosphere. It is necessary to have a perfect atmospheric model that allows disturbances to be calculated with high accuracy.

When solving problems of space photography and geodesy, it is necessary to particularly accurately integrate the equations of motion of satellites, taking into account all disturbing factors. These calculations are carried out in computer centers associated with space, for example, in the State Committee "Nature", and are issued to interested organizations. An engineer-surveyor, land surveyor, or photogrammetrist will need to interpolate the received data (coordinates and velocity components) for the moments of photographing.

1.2.1 Kepler's laws and orbital elements

In the theory of unperturbed motion of satellites, it is believed that the satellite rotates around the spherical Earth with an absolutely uniform distribution of masses in its body, and the force of attraction between the Earth and the satellite is the only reason for its orbital motion. In this case, the entire mass of the Earth can be considered concentrated at the center of mass and the motion of the satellite can be considered in the gravitational field created by the center of mass of the Earth. In this case, the satellite is considered as a material point with unit mass.

In this case, the motion of the satellite in orbit is described by Kepler’s laws, which we will formulate in relation to the motion of the Earth’s satellites.

Kepler's first law. The satellite moves in an ellipse, at one of the foci of which is the Earth's center of mass.

Kepler's second law. The radius vector of the satellite describes (“sweeps”) equal areas in equal periods of time.

Kepler's third law. The squares of the orbital periods of any two satellites are related as the cubes of the semimajor axes of their orbits.

Let point M be the focus at which the Earth's center of mass is located (Figure 2). Point P of the orbital ellipse closest to the focus M, called periapsis.

Figure 2 - Orbital ellipse.

Dot A, furthest from focus M called apocenter. Line connecting points A And P, called apse line, and the points themselves A And P-apses.

Let us introduce the orbital coordinate system X  , Y    Z  = 0, the beginning of which is at the point M(center of mass), positive axis direction X  coincides with the direction to the pericenter.

The polar coordinates in the orbital coordinate system are the radius vector and the true anomaly. The radius vector is drawn from the origin (point M) to the point i orbit where the satellite is located at the moment t i. True anomaly is the angle measured from the axis X  to the radius vector.

Equation of an ellipse in polar coordinates:

, (1.

Where a– semimajor axis of the orbit; – eccentricity of the orbit (ellipse);

– focal parameter.

Eccentricity is a characteristic of the elongation (oblateness) of the orbit and is equal to:

Where a– distance between the center and focus of the ellipse; b– semiminor axis of the ellipse.

Along with the true anomaly when describing the movement of satellites, planets and stars, they use eccentric anomalyE. We will conduct it from the center C ellipse is a circle with a radius equal to the semimajor axis a ellipse. From point i Let us lower the orbit perpendicular to the line of apses and continue it until it intersects with the drawn circle at a point. Connecting the dot with a dot C, we get the angle E between the direction to the pericenter and the direction to the point. If we take the eccentric anomaly E as an argument, then the equation of the ellipse will look like:

A consequence of Kepler's second law is the unevenness of the satellite's orbital motion. The orbital velocity reaches its maximum value at the periapsis, and its minimum value at the apocenter.

A corollary of Kepler's third law is the formula for the orbital period of an satellite:

(1.

where   is the geocentric gravitational constant,

G= 6.67259·10 –11 N·m 2 ·kg –2 - constant of universal gravitation;

M = 5.976·10 24 kg - mass of the Earth.

The quantity   is one of the fundamental geophysical constants.

We will determine the orientation of the orbital plane in space using Euler angles J,, and.

Orbital inclinationJ– the angle between the orbital plane and the equatorial plane. Corner J varies from 0° (the satellite moves along the equator from west to east) to 180° (the satellite moves in the opposite direction).

Longitude of the ascending node – the angle between the direction from the Earth’s center of mass to the vernal equinox point and the line of nodes (the line of intersection of the orbital plane and the equatorial plane).

Angle   –periapsis argument– measured from the positive direction of the line of nodes O to the apse line O (Figure 3).

Angles J,are called Euler angles, which determine the orientation of the orbital coordinate system relative to the geocentric coordinate system.

The angle is also often introduced U:

U=, (1.

which is called latitude argument.

Let's look at Figure 3. Here are indicated:

Oxyz –geocentric inertial coordinate system;

OXYZ –Greenwich geocentric coordinate system, which rotates along with the Earth around its axis OZ, making one revolution per sidereal day;

S i –sidereal time in Greenwich, equal to the angle between the axes Ox And OX at the moment t i ;

dot  –ascending node of orbit the satellite, which is the point of intersection of the equator and the orbit when the satellite moves from the southern hemisphere to the northern;

O  – the positive direction of the line of nodes along which the orbital plane and the plane of the earth’s equator intersect;

i – position of the satellite in orbit at the time of photographing t i ;

–geocentric radius vector Satellite at the time of photographing t i ;

 i And  i – geocentric right ascension And declination satellite;

Corner  –ascending node longitude; angle between axis direction Ox to the point of the vernal equinoxand the positive direction of the line of nodes O;

Corner J – inclination angle ( mood) the orbital plane to the equatorial plane;

Point  i –periapsis orbits, the point of the orbit closest to the Earth's center of mass (the focus of the orbital ellipse);

Corner  –periapsis argument, measured in the orbital plane from the positive direction of the line of nodes Oto direction Oto the pericenter.

Figure 3 - Satellite orbit in the Greenwich coordinate system

The inertial geocentric coordinates of the satellite are expressed through the radius vector r and Euler angles by the following formulas.