School encyclopedia. Where does the boundary of space begin? “Near” space is more profitable than distant space

Andrey Kislyakov, for RIA Novosti.

It would seem that it is not so important where “Earth” ends and space begins. Meanwhile, the debate surrounding the value of the height beyond which boundless outer space already extends has not subsided for almost a century. The latest data, obtained through a thorough study and synthesis of a large amount of information over almost two years, allowed Canadian scientists in the first half of April to declare that space begins at an altitude of 118 km. From the point of view of the influence of cosmic energy on the Earth, this number is very important for climatologists and geophysicists.

On the other hand, it is unlikely that it will soon be possible to finally end this dispute by establishing a single border that suits everyone. The fact is that there are several parameters that are considered fundamental for the corresponding assessment.

A little history. The fact that hard cosmic radiation operates outside the earth's atmosphere has been known for a long time. However, it was not possible to clearly define the boundaries of the atmosphere, measure the strength of electromagnetic flows and obtain their characteristics before the launch of artificial Earth satellites. Meanwhile, the main space task of both the USSR and the United States in the mid-50s was the preparation of a manned flight. This, in turn, required a clear knowledge of the conditions just beyond the earth's atmosphere.

Already on the second Soviet satellite, launched in November 1957, there were sensors for measuring solar ultraviolet, X-ray and other types of cosmic radiation. The discovery in 1958 of two radiation belts around the Earth was fundamentally important for the successful implementation of manned flights.

But let’s return to the 118 km established by Canadian scientists from the University of Calgary. Why, exactly, such a height? After all, the so-called “Karman line,” unofficially recognized as the boundary between the atmosphere and space, “passes” along the 100-kilometer mark. It is there that the air density is already so low that the aircraft must move at escape velocity (approximately 7.9 km/s) to prevent falling to Earth. But in this case, it no longer requires aerodynamic surfaces (wing, stabilizers). Based on this, the World Aeronautics Association adopted an altitude of 100 km as the watershed between aeronautics and astronautics.

But the degree of rarefaction of the atmosphere is far from the only parameter that determines the boundary of space. Moreover, the “earthly air” does not end at an altitude of 100 km. How, say, does the state of a substance change with increasing altitude? Maybe this is the main thing that determines the beginning of space? Americans, in turn, consider anyone who has been at an altitude of 80 km to be a true astronaut.

In Canada, they decided to identify the value of a parameter that appears to be important for our entire planet. They decided to find out at what altitude the influence of atmospheric winds ends and the influence of cosmic particle flows begins.

For this purpose, Canada developed a special device STII (Super - Thermal Ion Imager), which was launched into orbit from the spaceport in Alaska two years ago. With its help, it was established that the boundary between the atmosphere and space is located at an altitude of 118 kilometers above sea level.

At the same time, data collection lasted only five minutes, while the satellite carrying it rose to the altitude set for it of 200 km. This is the only way to collect information, since this mark is too high for stratospheric probes and too low for satellite research. For the first time, the study took into account all components, including air movement in the uppermost layers of the atmosphere.

Instruments like STII will be available to continue exploration of the frontier regions of space and the atmosphere as payloads on European Space Agency satellites that will have an active lifespan of four years. This is important because Continuing research in border regions will make it possible to learn many new facts about the impact of cosmic radiation on the Earth's climate and the impact that ion energy has on our environment.

Changes in the intensity of solar radiation, directly related to the appearance of sunspots on our star, somehow affect the temperature of the atmosphere, and the successors of the STII apparatus can be used to detect this effect. Already today, 12 different analyzing devices have been developed in Calgary to study various parameters of near space.

But there is no need to say that the beginning of space was limited to 118 km. After all, for their part, those who consider a height of 21 million kilometers to be real space are also right! It is there that the influence of the Earth's gravitational field practically disappears. What awaits researchers at such cosmic depths? After all, we didn’t go further than the Moon (384,000 km).

All processes occurring in the Universe are undoubtedly based on the laws of mechanics, since mechanical motion is a fundamental property of all objects of the micro- and macrocosm without exception, from electrons in an atom to giant stars.

Every completed scientific study must answer two questions: “What is going on?” and “Why is it happening.” It often happens that we know the answer only to the first question, while knowing the answer to the second of them seems more important.

The sacred questions, into the mysteries of answers to which the inquisitive human mind has sought to penetrate from time immemorial, remain: “How does the Cosmos work and what forces force various objects of Near Space to perform complex mechanical movements”, “How do cosmic objects interact with each other and what is the source of their disturbance” , “What reasons force all the planets to move around the Sun in orbits whose planes are only slightly deviated from the plane of the ecliptic, and in the same direction in which our star rotates around its own axis,” “What is the physical nature of solar and geomagnetic activity.”

The origin of the most important parameters of the orbital motion of the planets and their satellites - the nature of rotation, the distance to the center of rotation, the eccentricity of the orbit - is also fraught with uncertainty. Perhaps these parameters depend on the initial speed and initial angle of inclination that the space object had at the moment when it entered the sphere of gravity of the Sun or planet?

If we turn to our home planet - the Earth, then Galileo’s catchphrase involuntarily comes to mind: “And yet it turns!” But there is still no clear answer to the question: “Why is it spinning?”

It is well known that the Earth has its own magnetic field: this can be easily seen by looking at the position of the compass needle. But if there is a magnetic field, then there must be currents that create it. And since there are currents, what serves as their generator and where is the mysterious invisible person hidden? In this regard, a more global question arises: “What is the role of electro- and magnetodynamics in the formation of processes occurring in Space, and what is the contribution of electromagnetic and gravitational fields to these processes.”

If we turn to the processes occurring inside our planet, the number of unclear questions increases even more: according to what laws do the changes in geological epochs occur, what reasons drive mountain building, the change of biological species, are earthquakes and volcanic eruptions caused exclusively by endogenous factors or are they also to blame for this? outside disturbance.

Fundamentally substantiated answers to most of the questions posed do not yet exist. However, there are many scientific theories and concepts that strive to do this. We will also try* to provide clarification on some of the questions raised, and also show that the Near Space is a single oscillatory, self-exciting and self-organizing automatic control system.

Modern ideas about solar and geomagnetic activity

Compared to other stars, the Sun is so close to us that we can see and study its surface directly from Earth. With the help of optical instruments, it is possible to detect the layers enveloping the Sun and trace in all details the processes occurring in its atmosphere.

Conventionally, the solar atmosphere is divided into several layers, passing into one another: the outer, most rarefied layer - the corona, the underlying chromosphere - red and the photosphere - the luminous layer. Photosphere - a layer of gas no more than 200 km thick, visible dazzling surface

As is known, six decades have passed since the launch of the first satellite. At the moment, scientists are coming to the conclusion that it is cheaper and safer to explore the stratosphere rather than space.

Today, thousands of devices fly in orbit, such as communications satellites, space observatories, probes for various purposes, and others. At first glance, the space sector is making great progress, but everything is not as simple as journalist Igor Tirsky claims.

Are there prospects in space exploration?

Businessmen have recently become interested in the space theme, as they have discovered the possibility of private space exploration, the colonization of Mars and the Moon, and the processing of asteroids. In the near future, entrepreneurs will be able to provide offers to all volunteers to make suborbital flights at an altitude of approximately 100 km. above the planet, and this is almost space.

Thus, people who are very far from this have also become interested in space, such as Elon Musk, Richard Branson, Paul Allen, Vladislav Filev and Jeff Bezos, who are entrepreneurs from the West.

In the future, a certain boom in space tourism is expected, the launching of thousands of satellites into orbit in order to distribute Internet connections, as well as the construction of bases on Mars and the Moon led by private companies and the movement of millions of tourists to new places.

This is not a joke, because such thoughts are part of the actual plans of entrepreneurs in the field of private space. For example, Elon Musk, who is the head of SpaceX, makes promises to send a million people to Mars.

It is likely that in the foreseeable future, the near-Earth space will gradually be occupied by humanity. We will take root there thoroughly. At the same time, there will be a sharp increase in the number of functioning spacecraft in Earth orbit.

Another scenario

Space is very complex and expensive, and studying it takes a lot of time, so few people are interested in the business prospects for its exploration. At the moment, all services in this area are available only to the state and large private organizations, which also enjoy state support. Even for these organizations, investing in space is highly risky. After all, in orbit, vehicle failures, explosions of launch vehicles, etc. are quite possible. Of course, space technology is insured, and this insurance can cover all kinds of expenses, however, creating another device will require a colossal amount of time.

Even in the case of successful launch of devices into orbit, contributions may, so to speak, “not be recovered,” and technologies tend to become obsolete. For example, there are satellites such as Iridium, which provide space communications via satellite phone anywhere on Earth. The first call in this system was made in 1997, but the technology was conceived ten years ago, in 1987, and then few people knew about cellular communications.

Today we see that the Internet has turned out to be a simpler and cheaper solution in this regard. And cell towers are built this way in many countries. "LTE" is no longer as outlandish as it used to be. Today you can be more surprised by a person with a satellite phone. Thus, “Iridium” turned out to be not in demand among the masses, because there is cellular communication, and besides, there are satellite services from other providers that cost much less than the technology described above. Iridium still exists today, but they cannot withstand the competition, because other providers offer the same technologies at a lower cost.

A similar thing is happening now, only with regard to the World Wide Web, because OneWeb and SpaceX intend to launch thousands of artificial earth satellites equipped with antennas for distributing the Internet throughout the Earth.

In other words, any inhabitant of the planet will have the opportunity to use high-speed satellite Internet at a very reasonable cost or completely free of charge, which depends on the monetization model. But this is relevant for modern people, because despite the development of technology, approximately half of the planet’s population still cannot use the Internet.

The same situation arose with Motorola when it launched Iridium. After all, in the late 80s we didn’t even dream of such a scale of mobile communications as it is now, and the company already set intentions to cover the whole world with its network. Nowadays, cellular communications are available even in remote corners of the planet, but the quality of the Internet is still poor, which is why the above-mentioned companies want to tackle this problem.

Satellite Internet seems to be a very good alternative to cellular or cable. It is not as expensive as it might seem at first glance when it comes to one-way access. After all, here you only need to have a simple antenna and relatively cheap equipment for receiving the signal. For the outgoing channel, technologies such as ADSL, GPRS, 3G, etc. are used here. But in those territories where there is no terrestrial connection, the situation is more complicated, so there it is necessary to introduce a duplex rather than a simplex (one-way) network. In this case, the terminal operates simultaneously in the mode of a transmitting and receiving device, but this option will be more expensive.

Currently, satellite and cellular companies are in competition with fiber optic cable, because this technology is not yet widespread everywhere. However, everything is heading towards the fact that the planet will be surrounded by cable, and in this case, space networks will not be useful to us.

Therefore, the question arises about the profitability in the future of such communication systems as those that SpaceX and OneWeb are planning to implement.

Probably, the need for the Internet via satellites will only be in India, Africa and other hard-to-reach places where it is not possible to lay a cable or build many LTE towers. This raises the question of whether the cost of such technologies will be acceptable and whether the authorities will allow it to be implemented. Therefore, it seems that satellite Internet will remain uncontested for a long time, but the situation may change a lot.

Drones and stratospheric balloons - an alternative to rockets and satellites

Satellites are used not only for the purpose of delivering the Internet, but also for the so-called remote sensing of the planet, in other words, for capturing the surface in photographs and transmitting data. However, we can now see the development of drones and unmanned aerial vehicles designed for sensing. After all, they are cheap, have the ability to be mobile, can be serviced on the ground, and can also be controlled manually.

So the question arises, why do we need a satellite in orbit if there are drones that are not afraid of clouds, because they can simply descend under them and problems will be eliminated. You can also increase the image resolution by lowering the position. Drones are also capable of circling over the same area for a long time and collecting data there in real time. All of the above-mentioned abilities are very cheap compared to a satellite system, because when operating a satellite system, hundreds of devices are needed to make it possible to carry out a sightseeing trip over the area. This will all cost billions of dollars. Significant difference, isn't it?

Many people think that space observatories cannot be replaced. This was not the case, because there are projects such as VLT, E-ELT, which is a huge telescope, and SOFIA, which is an observatory on an airplane. This is a completely worthy alternative, but not for all wavelength ranges. In this case, stratospheric balloons capable of rising to heights of approximately 40-50 km will help. above the earth's surface and carry large loads, for example, an observatory. As an advantage, we can note that they do not have problems with microgravity. When moving such devices, there is no high load, which is usually taken into account in launch vehicles, increasing the mass and significantly limiting the possibility of all kinds of improvements. Such devices can be serviced at any time, even during operation, because you can simply fly up to it in another balloon or lower it to the ground for repairs.

Back in 1961, they initiated a project for a stratospheric solar station with a mirror-type telescope called “Saturn”. The diameter of the main mirror there was 50 cm. In 1973, images of the Sun were already taken using a modernized device with a meter-long mirror from a height of 20 km. above the earth's surface.

They say that the heights are from 20 to 100 km. are considered “near space” due to their similarity to real space. It is no longer possible for a person to be there without a protective suit, and the view from the window is approximately the same as in orbit, only you cannot see the satellites, and the sky is dark purple and black-linden in color, although at first glance it is black in contrast with the bright star and the surface of the Earth.

Real space is already above 100 km. There, for sufficient lifting force, it is necessary to have a speed higher than the first cosmic speed. This is no longer an airplane, but a satellite. In practice, the difference here is in the method of delivery: flights into real space are carried out on rockets, and in near space - on stratospheric balloons.

Strato balloons are technologies forgotten by everyone from the distant 30s of the 20th century. They are not airships filled with hydrogen and exploding from any spark. They are more like helium balloons, which are capable of rising into near space up to 50 km. There are projects of launchostats operating at an altitude of 80 km, but it would be more correct to call them suborbital satellites. These options are intended for the military; for civilians, the models are not capable of rising above 50 km. But also 50 km. enough to solve more problems.

Stratostats have ceased to be relevant since the beginning of the space age in 1957, that is, with the launch of the first satellite. However, 60 years have passed, and for some reason they were remembered. Surely, people are talking about them now because of their cheapness in comparison with satellites, because not every country has access to satellite technologies and a full-fledged space program, and many people have the opportunity to study the stratosphere. The point is not only in cheapness, but also in the features of the technologies themselves, which allow the devices to remain in the sky for hundreds of days.

After all, during the day, stratospheric balloons are powered by solar panels, and their powerful batteries store energy at night, while they are very light in weight. The design of the device is quite light and durable. GPS gives them the ability to easily determine their position, and on-board computers are capable of making independent decisions.

It is precisely the complex of all kinds of modern technologies that makes it possible to talk about the demand for stratospheric services in the market.

For example, the WorldView company has plans to launch tourists to altitudes of up to 45 km, for which a new gondola was invented, equipped with huge windows, from where tourists will be able to observe the blackness of the daytime sky and the surface of the Earth, one might say, as astronauts see it.

“Near” space is more profitable than distant space

In this case, only navigation such as GPS, GLONASS, Beidou and Galileo will be left in real space. However, this problem can be solved without the use of expensive satellite technologies - through stratospheric balloons, drones and other means. In addition, LTE and Wi-Fi are currently acting as good alternatives to GPS. LBS navigates well and determines location based on cell towers and Wi-Fi. Only it loses exactly, because the error here is tens of meters, while “GPS” has less than a meter.

Thus, “Near space” or the stratosphere in the near future is quite capable of taking the main place in the scientific field, outperforming near-Earth orbit due to its attractive conditions.

Send stratospheric balloons equipped with special equipment and even an entire laboratory, together with people on board, to altitudes of up to 50 km. will become more and more frequent, so that it will become normal. In this case, it will not even be necessary to provide stratonauts with protection from radiation, solar storms, space debris, etc. In the future, we may even stop focusing on space and turn our attention to the atmosphere, since it seems much cheaper to create drones and stratospheric balloons. In this case, there will not even be a need to provide such a protection and life support system as would be necessary in earth orbit.

As for national economic tasks, such as communications, sounding, scientific experiments, astronomy, here stratospheric balloons act as very strong competitors to satellites, because people will create much cheaper versions of the devices. Such devices will be capable of making independent decisions in terms of where to move and how to group. This is already being developed within the framework of a project called “Google Loon”, which gives the opportunity to hard-to-reach regions to use Internet technologies. Such devices are also called models controlled by a neural network. It is also worth talking here about autonomous drones that can stay in the atmosphere for many days.

Stratostats are capable of continuous observation of the same area of the planet. Such devices are also geostationary. It is known that there are no strong winds and low turbulence in the stratosphere, so the stratospheric balloon is quite capable of hovering over one point, like a satellite. But to deliver a satellite to geostationary orbit, which is 36 thousand km. above the earth's surface, a powerful launch vehicle is used, but in the case of delivery of a stratospheric balloon, helium cylinders, a little funding, and that's all. Thus, stratospheric balloons are quite competitive with conventional communication and sensing technologies.

Thus, as stratospheric science develops, expensive probes and conventional communication technologies will be abandoned. Also, stratospheric balloons can serve as an excellent tool for launching the same satellites from the stratosphere. So simply the technology for delivering satellites into orbit will change. After all, the company “Zero 2 Infinity” is working in this promising direction. The stratospheric balloon will serve as a cosmodrome or a platform for launching a satellite into real space. Even if investors do not properly support this project, the direction in terms of development of the stratosphere is still clearly outlined.

A large number of stratospheric balloons in our atmosphere are capable of creating a kind of global communication system, similar to that formed through computers at home.

Consequently, we will be able to receive data from the probes directly to our personal devices, better know the weather, connect to an Internet connection with minimal signal delay even in hard-to-reach places on Earth, communicate through such devices in a decentralized manner, etc.

That is, any information received from the stratospheric balloon will be processed much more accurately and quickly than data from orbit. Thus, the philosophy of the so-called decentralized Internet should extend to other areas, and the technologies described above, such as stratospheric balloons and drones, are ideal for building such a model of the world.

Conclusion

Consequently, we can talk about a new era of technology development, where the cheapest options will be used both for organizations involved in the space sector and for ordinary people using the Internet and other means of communication. The exploration of near space is a very interesting prospect, because in this case everyone will have access to the study of the stratosphere, people will be able to explore the Earth from an altitude of 50 km. from its surface. This, of course, will open up cheap and accessible opportunities for all humanity in space exploration, albeit nearby ones. This is an expansion of space for traveling around the Earth at enormous altitudes. Therefore, the possibility of switching from satellite technologies to stratospheric balloons and similar devices is now being considered. In addition, this will also expand the capabilities of the Internet and make it cheaper and more accessible even to residents of the most remote corners of the planet. So all that remains is to wait for the implementation of such projects from leading space companies.

Everyone has traveled at some point, spending a specific amount of time to complete the journey. How endless the road seemed when it was measured in days. From the capital of Russia to the Far East – seven days by train! What if we use this transport to cover distances in space? To get to Alpha Centauri by train it will take only 20 million years. No, it’s better to go by plane - it’s five times faster. And this is up to the star nearby. Of course, nearby - this is by stellar standards.

Distance to the Sun

Even two hundred years before our era, he tried to determine the distance to. But his calculations were not very correct - he was wrong by 20 times. More accurate values were obtained by the Cassini spacecraft in 1672. The positions during its opposition were measured from two different points on the Earth. The calculated distance to the Sun was 140 million km. In the middle of the twentieth century, with the help of radar, the true parameters of the distances to the planets and the Sun were revealed.

We now know that the distance from the earth to the Sun is 149,597,870,691 meters. This value is called the astronomical unit, and it is the basis for determining cosmic distances using the stellar parallax method.

Long-term observations have also shown that the Earth moves away from the Sun by about 15 meters every 100 years.

Distances to nearest objects

We don't think much about distance when we watch live broadcasts from the far corners of the globe. The television signal reaches us almost instantly. Even from our satellite, radio waves reach us in just over a second. But as soon as you start talking about objects that are more distant, surprise immediately comes. Does it really take 8.3 minutes for light to reach such a close Sun, and 5.5 hours to reach the icy Sun? And this, flying almost 300,000 km in a second! And in order to get to the same Alpha in the constellation Centaurus, a beam of light will need 4.25 years.

Even for near space our usual units of measurement are not entirely suitable. Of course, you can take measurements in kilometers, but then the numbers will not cause respect, but some fear due to their size. For ours, it is customary to carry out measurements in astronomical units.

Now cosmic distances to planets and other near-space objects will not look so scary. From our star to only 0.387 AU, and to - 5.203 AU. Even to the most distant planet - - only 39.518 AU.

The distance to the Moon is accurate to the nearest kilometer. This was done by placing corner reflectors on its surface and using the laser ranging method. The average distance to the Moon was 384,403 km. But the solar system extends much further than the orbit of the last planet. The system border is as much as 150,000 a.m. e. Even these units begin to be expressed in grandiose quantities. Other measurement standards are appropriate here, because distances in space and the size of our Universe are beyond the boundaries of reasonable concepts.

Middle space

There is nothing faster than light in nature (such sources are not yet known), so it was its speed that was taken as the basis. For objects closest to our planetary system and for those distant from it, the path traveled by light in one year is taken as unit. It takes about two years for light to travel to the edge of the Solar System, and 4.25 light years to the nearest star in Centaurus. of the year. The well-known Polar Star is located 460 sv away from us. years.

Each of us has dreamed of traveling to the past or future. Traveling into the past is quite possible. You just need to look into the starry night sky - this is the past, distant and infinitely distant.

We observe all space objects in their distant past, and the further away the observed object is, the further into the past we look. While the light flies from a distant star to us, so much time passes that perhaps at the moment this star no longer exists!

The brightest star in our sky - Sirius - will go out for us only 9 years after its death, and the red giant Betelgeuse - only after 650 years.

It has a diameter of 100,000 light. years, and a thickness of about 1,000 light. years. It is incredibly difficult to imagine such distances, and almost impossible to estimate them. Our Earth, together with its star and other objects of the solar system, revolves around the center in 225 million years, and makes one revolution every 150,000 light years. years.

Deep space

Distances in space to distant objects are measured using the parallax (displacement) method. Another unit of measurement flowed from it - parsec Parsec (pc) - from parallactic second This is the distance from which the radius of the earth's orbit is observed at an angle of 1″.. The value of one parsec was 3.26 light. year or 206,265 a. e. Accordingly, there are thousands of parsecs (Kpc) and millions (Mpc). And the most distant objects in the Universe will be expressed in distances of a billion parsecs (Gpc). The parallactic method can be used to determine distances to objects distant no further than 100 pc, b O Longer distances will have very significant measurement errors. The photometric method is used to study distant cosmic bodies. This method is based on the properties of the object located at a distance of 660 kpc. The group of galaxies in the constellation Ursa Major is 2.64 Mpc away from us. And the visible one is 46 billion light years, or 14 Gpc!

Measurements from space

To improve the accuracy of measurements, the Hipparchus satellite was launched in 1989. The satellite's task was to determine the parallaxes of more than 100 thousand stars with millisecond accuracy. As a result of observations, distances were calculated for 118,218 stars. These included more than 200 Cepheids. For some objects, previously known parameters have changed. For example, the open star cluster Pleiades approached - instead of 135 pc of the previous distance, it turned out to be only 118 pc.

What is the planet Venus, closed from observers on Earth by a dense atmosphere? What does the surface of Mars look like and what is the composition of the Martian atmosphere? Telescopes could not answer these questions. But everything changed with the advent of radar.

It turned out that radio waves sent by radars from the Earth are reflected from cosmic bodies in the same way as and from earthly objects. By sending radio signals to a specific astronomical body and analyzing the signals reflected from it, you can obtain information about the space object.

This is how radar radio astronomy appeared, exploring the planets and their satellites, comets, asteroids and even the solar corona using radio signals.

Near and deep space

Near and far space are often distinguished. The border between them is very arbitrary.

Near space is space explored by spacecraft and interplanetary stations, and distant space is space outside the solar system. Although a clear boundary between them has not been established.

It is believed that near space is located above the Earth's atmospheric layer, rotating with it and called near-Earth space. There is no longer an atmosphere in near space, but all objects located in it are still affected by the gravitational field of our planet. And the further from Earth, the smaller this influence becomes.

Deep space objects - stars, galaxies, nebulae, black holes located outside the Solar System.

Near space is inhabited by planets of the solar system, satellites, asteroids, comets, and the Sun. According to cosmic concepts, the distance between them and the Earth is considered small. Therefore, they can be studied using radars located on Earth. These are special powerful radars called planetary radars.

Radar exploration of near space

Center for Deep Space Communications in Evpatoria

Space radars operate on the same physical principle as conventional ground-based radars serving ships and aircraft. The radio transmitting device of a planetary radar generates radio waves that are directed to the space object under study. The echo signals reflected from it are caught by the receiving device.

But due to the enormous distance, the radio signal reflected from the space object becomes much weaker. Therefore, transmitters on planetary radars have very high power, antennas are large, and receivers are very sensitive. For example, the diameter of the radio antenna mirror at the Center for Deep Space Communications near Evpatoria is 70 m.

The first planet to be explored using radar was the Moon. By the way, the idea of sending a radio signal to the Moon and then receiving its reflection arose back in 1928 and was put forward by Russian scientists Leonid Isaakovich Mandelstam and Nikolai Dmitrievich Papaleksi. But it was technically impossible to implement it at that time.

Leonid Isaakovich Mandelstam

Nikolai Dmitrievich Papaleksi

This was done in 1946 by American and Hungarian scientists independently of each other. A radio signal sent from a powerful radar towards the Moon was reflected from its surface and returned to Earth after 2.5 seconds. This experiment allowed us to calculate the exact distance to the Moon. But at the same time, from the picture of the reflected waves, it was possible to determine the relief of its surface.

In 1959, the first signals reflected from the solar corona were received. In 1961, a radar signal went towards Venus. Highly penetrating radio waves penetrated its thick atmosphere and made it possible to “see” its surface.

Then exploration of Mercury, Mars, Jupiter and Saturn began. Radar helped to determine the sizes of planets, the parameters of their orbits, the diameters and speed of their rotation around the Sun, and also to study their surfaces. Using radar, the exact dimensions of the solar system were established.

Radio signals are reflected not only from the surfaces of celestial bodies, but also from ionized traces of meteor particles in the Earth's atmosphere. Most often, these traces appear at an altitude of about 100 km. And although they exist from 1 to several seconds, this is enough to use reflected pulses to determine the size of the particles themselves, their speed and direction.

Onboard radars on controlled space objects

Small spacecraft (SSV) "Condor-E" with radar