Van Allen radiation belt. The reasons for the successful flight of astronauts through the earth's radiation belt are named

Earth's radiation belt

Another name (usually in Western literature) is “Van Allen radiation belt”.

Inside the magnetosphere, as in any dipole field, there are areas inaccessible to particles with kinetic energy E, less than critical. The same particles with energy E < E kr, who are already there, cannot leave these areas. These forbidden regions of the magnetosphere are called capture zones. In the capture zones of the Earth's dipole (quasi-dipole) field, significant fluxes of captured particles (primarily protons and electrons) are indeed retained.

The Earth's radiation belt (inner) was predicted by Soviet scientists S.N. Vernov and A.E. Chudakov, as well as the American scientist James Van Allen. The existence of the radiation belt was demonstrated by measurements on Sputnik 2, launched in 1957, and also on Explorer 1, launched in 1958. To a first approximation, the radiation belt is a toroid, in which two regions are distinguished:

an inner radiation belt at an altitude of ≈ 4000 km, consisting predominantly of protons with energies in the tens of MeV;
outer radiation belt at an altitude of ≈ 17,000 km, consisting predominantly of electrons with energies in the tens of keV.

The height of the lower boundary of the radiation belt varies at the same geographical latitude in longitude due to the inclination of the axis of the Earth's magnetic field to the axis of rotation of the Earth, and at the same geographical longitude it changes in latitude due to the own shape of the radiation belt, due to different height of the Earth's magnetic field lines. For example, over the Atlantic, the increase in radiation intensity begins at an altitude of 500 km, and over Indonesia at an altitude of 1300 km. If the same graphs are plotted as a function of magnetic induction, then all measurements will fit on one curve, which once again confirms the magnetic nature of particle capture.

There is a gap between the inner and outer radiation belts, located in the range from 2 to 3 Earth radii. Particle fluxes in the outer belt are greater than in the inner one. The composition of the particles is also different: in the inner belt there are protons and electrons, in the outer belt there are electrons. The use of unshielded detectors has significantly expanded information about radiation belts. Electrons and protons with energies of several tens and hundreds of kiloelectronvolts, respectively, were discovered. These particles have a significantly different spatial distribution (compared to penetrating particles).

The maximum intensity of low-energy protons is located at a distance of about 3 Earth radii from its center. Low-energy electrons fill the entire capture region. For them there is no division into internal and external belts. It is unusual to classify particles with energies of tens of keV as cosmic rays, but radiation belts are a single phenomenon and should be studied in conjunction with particles of all energies.

The proton flux in the inner belt is quite stable over time. Early experiments showed that high energy electrons ( E> 1-5 MeV) are concentrated in the outer belt. Electrons with energies less than 1 MeV fill almost the entire magnetosphere. The inner belt is very stable, while the outer one experiences sharp fluctuations.

Radiation belts of planets

Due to the presence of a strong magnetic field, the giant planets (Jupiter, Saturn, Uranus and Neptune) also have strong radiation belts, reminiscent of the outer radiation belt

As already mentioned, as soon as the Americans began their space program, their scientist James Van Allen made a rather important discovery. The first American artificial satellite they launched into orbit was much smaller than the Soviet one, but Van Allen thought of attaching a Geiger counter to it. Thus, what was expressed at the end of the 19th century was officially confirmed. The outstanding scientist Nikola Tesla hypothesized that the Earth is surrounded by a belt of intense radiation.

Photograph of Earth by astronaut William Anders

during the Apollo 8 mission (NASA archives)

Tesla, however, was considered a great eccentric, and even a madman by academic science, so his hypotheses about the gigantic electric charge generated by the Sun were shelved for a long time, and the term “solar wind” did not cause anything but smiles. But thanks to Van Allen, Tesla's theories were revived. At the instigation of Van Allen and a number of other researchers, it was established that radiation belts in space begin at 800 km above the Earth's surface and extend up to 24,000 km. Since the radiation level there is more or less constant, the incoming radiation should be approximately equal to the outgoing radiation. Otherwise, it would either accumulate until it “baked” the Earth, as in an oven, or it would dry up. On this occasion, Van Allen wrote: “Radiation belts can be compared to a leaky vessel, which is constantly replenished from the Sun and flows into the atmosphere. A large portion of solar particles overflows the vessel and splashes out, especially in the polar zones, leading to polar lights, magnetic storms and other similar phenomena.”

Radiation from the Van Allen belts depends on the solar wind. In addition, they appear to focus or concentrate this radiation within themselves. But since they can only concentrate in themselves what came directly from the Sun, one more question remains open: how much radiation is in the rest of the cosmos?

Orbits of atmospheric particles in the exosphere(dic.academic.ru)

The Moon does not have Van Allen belts. She also has no protective atmosphere. It is open to all solar winds. If a strong solar flare had occurred during the lunar expedition, a colossal flow of radiation would have incinerated both the capsules and the astronauts on the part of the lunar surface where they spent their day. This radiation is not just dangerous - it is deadly!

In 1963, Soviet scientists told renowned British astronomer Bernard Lovell that they did not know of a way to protect cosmonauts from the deadly effects of cosmic radiation. This meant that even the much thicker metal shells of the Russian devices could not cope with the radiation. How could the thinnest (almost like foil) metal used in American capsules protect astronauts? NASA knew this was impossible. The space monkeys died less than 10 days after returning, but NASA has never told us the true cause of their demise.

Monkey-astronaut (RGANT archive)

Most people, even those knowledgeable in space, are not aware of the existence of deadly radiation permeating its expanses. Oddly enough (or perhaps just for reasons that can be guessed), in the American “Illustrated Encyclopedia of Space Technology” the phrase “cosmic radiation” does not appear even once. And in general, American researchers (especially those associated with NASA) avoid this topic a mile away.

Meanwhile, Lovell, after talking with Russian colleagues who were well aware of cosmic radiation, sent the information he had to NASA administrator Hugh Dryden, but he ignored it.

One of the astronauts who allegedly visited the Moon, Collins, mentioned cosmic radiation only twice in his book:

"At least the Moon was well beyond Earth's Van Allen belts, which meant a good dose of radiation for those who went there and a lethal dose for those who lingered."

“Thus, the Van Allen radiation belts surrounding the Earth and the possibility of solar flares require understanding and preparation to avoid exposing the crew to increased doses of radiation.”

So what does “understand and prepare” mean? Does this mean that beyond the Van Allen belts, the rest of space is free of radiation? Or did NASA have a secret strategy for sheltering from solar flares after making the final decision on the expedition?

NASA claimed that it could simply predict solar flares, and therefore sent astronauts to the Moon when flares were not expected and the radiation danger to them was minimal.

While Armstrong and Aldrin were doing work in outer space

on the surface of the moon, Michael Collins

placed in orbit (NASA archive)

However, other experts say: “It is only possible to predict the approximate date of future maximum radiation and its density.”

The Soviet cosmonaut Leonov nevertheless went into outer space in 1966 - however, in a super-heavy lead suit. But just three years later, American astronauts jumped on the surface of the Moon, and not in super-heavy spacesuits, but rather quite the opposite! Maybe over the years, specialists from NASA have managed to find some kind of ultra-light material that reliably protects against radiation?

However, researchers suddenly find out that at least Apollo 10, Apollo 11 and Apollo 12 set off precisely during those periods when the number of sunspots and the corresponding solar activity were approaching a maximum. The generally accepted theoretical maximum of solar cycle 20 lasted from December 1968 to December 1969. During this period, the Apollo 8, Apollo 9, Apollo 10, Apollo 11, and Apollo 12 missions supposedly moved beyond the protection zone of the Van Allen belts and entered cislunar space.

Further study of monthly graphs showed that single solar flares are a random phenomenon, occurring spontaneously over an 11-year cycle. It also happens that during the “low” period of the cycle a large number of outbreaks occur in a short period of time, and during the “high” period - a very small number. But what is important is that very strong outbreaks can occur at any time of the cycle.

During the Apollo era, American astronauts spent a total of almost 90 days in space. Since radiation from unpredictable solar flares reaches the Earth or Moon in less than 15 minutes, the only way to protect against it would be to use lead containers. But if the rocket’s power was enough to lift such an extra weight, then why was it necessary to go into space in tiny capsules (literally 0.1 mm of aluminum) at a pressure of 0.34 atmospheres?

This is despite the fact that even a thin layer of protective coating, called “mylar,” according to the Apollo 11 crew, turned out to be so heavy that it had to be urgently removed from the lunar module!

It seems that NASA selected special guys for lunar expeditions, albeit adjusted for circumstances, cast not from steel, but from lead. The American researcher of the problem, Ralph Rene, was not too lazy to calculate how often each of the supposedly completed lunar expeditions should have been affected by solar activity.

By the way, one of the authoritative employees of NASA (distinguished physicist, by the way) Bill Modlin, in his work “Prospects for Interstellar Travel,” frankly reported: “Solar flares can emit GeV protons in the same energy range as most cosmic particles, but much more intense . The increase in their energy with increased radiation poses a particular danger, since GeV protons penetrate several meters of material... Solar (or stellar) flares with the emission of protons are a periodically occurring very serious danger in interplanetary space, which provides a radiation dose of hundreds of thousands of roentgens in a few hours at the distance from the Sun to the Earth. This dose is lethal and millions of times higher than permissible. Death can occur after 500 roentgens in a short period of time.”

Yes, the brave American guys then had to shine worse than the fourth Chernobyl power unit. “Cosmic particles are dangerous, they come from all directions and require a minimum of two meters of dense shielding around any living organisms.” But the space capsules that NASA demonstrates to this day were just over 4 m in diameter. With the thickness of the walls recommended by Modlin, the astronauts, even without any equipment, would not have fit into them, not to mention the fact that there would not have been enough fuel to lift such capsules. But, obviously, neither the NASA leadership nor the astronauts they sent to the Moon read their colleague’s books and, being blissfully unaware, overcame all the thorns on the road to the stars.

However, maybe NASA actually developed some kind of ultra-reliable spacesuits for them, using (obviously, very secret) ultra-light material that protects against radiation? But why wasn’t it used anywhere else, as they say, for peaceful purposes? Well, okay, they didn’t want to help the USSR with Chernobyl: after all, perestroika had not yet begun. But, for example, in 1979, in the same USA, a major reactor unit accident occurred at the Three Mile Island nuclear power plant, which led to a meltdown of the reactor core. So why didn’t the American liquidators use space suits based on the much-advertised NASA technology, costing no less than $7 million, to eliminate this delayed-action nuclear mine on their territory?..

The Earth's Radiation Belt (ERB), or Van Allen Belt, is a region of the nearest outer space near our planet, shaped like a ring, in which there are giant flows of electrons and protons. The Earth holds them with a dipole magnetic field.

Opening

RPZ was discovered in 1957-58. scientists from the United States and the USSR. Explorer 1 (pictured below), the first US space satellite launched in 1958, provided very important data. Thanks to an onboard experiment conducted by the Americans above the Earth's surface (at an altitude of approximately 1000 km), a radiation belt (inner) was found. Later, a second such zone was discovered at an altitude of about 20,000 km. There is no clear boundary between the inner and outer belts - the first gradually turns into the second. These two zones of radioactivity differ in the degree of charge of the particles and their composition.

These areas became known as the Van Allen belts. James Van Allen is a physicist whose experiment helped discover them. Scientists have found that these belts consist of solar wind and charged cosmic ray particles that are attracted to the Earth by its magnetic field. Each of them forms a torus around our planet (a figure that is shaped like a donut).

Since that time, many experiments have been carried out in space. They made it possible to study the main features and properties of the ERP. Not only our planet has radiation belts. They are also found in other celestial bodies that have an atmosphere and a magnetic field. The Van Allen radiation belt was discovered by US spacecraft near Mars. In addition, the Americans found it near Saturn and Jupiter.

Dipole magnetic field

Our planet has not only the Van Allen belt, but also a dipole magnetic field. It is a set of magnetic shells nested inside each other. The structure of this field resembles a head of cabbage or an onion. The magnetic shell can be imagined as a closed surface woven from magnetic lines of force. The closer the shell is to the center of the dipole, the greater the magnetic field strength becomes. In addition, the momentum required for a charged particle to penetrate it from outside also increases.

So, the Nth shell has Pn. In the case when the initial momentum of the particle does not exceed Pn, it is reflected by the magnetic field. The particle then returns to outer space. However, it also happens that it ends up on the N-th shell. In this case, she is no longer able to leave her. The captured particle will remain trapped until it dissipates or, colliding with the residual atmosphere, loses energy.

On our planet, the same shell is located at different distances from the earth's surface at different longitudes. This occurs due to the mismatch of the axis of the magnetic field with the axis of rotation of the planet. This effect is most noticeable over the Brazilian magnetic anomaly. In this region, magnetic field lines descend, and captured particles moving along them may end up below 100 km altitude, and therefore die in the earth's atmosphere.

Composition of the RPZ

Within the radiation belt, the distribution of protons and electrons is unequal. The former are located in its inner part, and the latter in its outer part. Therefore, at an early stage of research, scientists believed that there were external (electronic) and internal (proton) radiation belts of the Earth. Currently, this opinion is no longer relevant.

The most significant mechanism for the generation of particles filling the Van Allen Belt is the decay of albedo neutrons. It should be noted that neutrons are created when the atmosphere interacts with the flow of these particles moving away from our planet (albedo neutrons) passes through the Earth's magnetic field unhindered. However, they are unstable and easily decay into electrons, protons and electron antineutrinos. Radioactive albedo nuclei, which have high energy, decay inside the capture zone. This is how the Van Allen Belt is replenished with positrons and electrons.

ERP and magnetic storms

When these particles become strong, they not only accelerate, they leave the Van Allen radioactive belt, spilling out of it. The fact is that if the configuration of the magnetic field changes, the mirror points can be immersed in the atmosphere. In this case, the particles, losing energy (ionization losses, scattering), change their pitch angles and then die when they reach the upper layers of the magnetosphere.

RPZ and Northern Lights

The Van Allen radiation belt is surrounded by a plasma layer, which is a trapped stream of protons (ions) and electrons. One of the reasons for such a phenomenon as the northern (polar) lights is that particles spill out from the plasma layer, and also partly from the external ERB. The Northern Lights are the radiation of atmospheric atoms that are excited due to collisions with particles falling from the belt.

RPZ Study

Almost all of the seminal research results on formations such as radiation belts were obtained around the 1960s and 70s. Recent observations using interplanetary spacecraft and the latest scientific equipment have allowed scientists to obtain very important new information. The Van Allen belts around the Earth continue to be studied in our time. Let us briefly talk about the most important achievements in this area.

Data received from Salyut-6

Researchers from MEPhI in the early 80s of the last century studied the flow of electrons with a high level of energy in the immediate vicinity of our planet. To do this, they used equipment that was located at the Salyut-6 orbital station. It allowed scientists to very effectively isolate fluxes of positrons and electrons whose energy exceeds 40 MeV. The station's orbit (inclination 52°, altitude about 350-400 km) passed mainly below the radiation belt of our planet. However, it still touched the inner part of it near the Brazilian magnetic anomaly. When crossing this region, stationary flows consisting of high-energy electrons were found. Before this experiment, only electrons whose energy did not exceed 5 MeV were recorded in the ERP.

Data from artificial satellites of the Meteor-3 series

Researchers from MEPhI carried out further measurements on the artificial satellites of our planet of the Meteor-3 series, whose circular orbit altitudes were 800 and 1200 km. This time the device penetrated very deeply into the RRP. He confirmed the results that were obtained earlier at the Salyut-6 station. Then the researchers obtained another important result using magnetic spectrometers installed at the Mir and Salyut-7 stations. It was proven that the previously discovered stable belt consists exclusively of electrons (without positrons), the energy of which is very high (up to 200 MeV).

Discovery of the stationary belt of CNO nuclei

A group of researchers from the Scientific Research Nuclear Physics Institute of Moscow State University in the late 80s and early 90s of the last century carried out an experiment aimed at studying nuclei located in nearby outer space. These measurements were carried out using proportional chambers and nuclear photographic emulsions. They were carried out on satellites of the Cosmos series. Scientists have discovered the presence of fluxes of N, O and Ne nuclei in a region of outer space in which the orbit of an artificial satellite (inclination 52°, altitude about 400-500 km) crossed the Brazilian anomaly.

As the analysis showed, these nuclei, the energy of which reached several tens of MeV/nucleon, were not of galactic, albedo or solar origin, since they could not penetrate deeply into the magnetosphere of our planet with such energy. This is how scientists discovered an anomalous component of cosmic rays captured by a magnetic field.

Low-energy atoms found in interstellar matter are able to penetrate the heliosphere. Then the ultraviolet radiation of the Sun ionizes them once or twice. The resulting charged particles are accelerated at solar wind fronts, reaching several tens of MeV/nucleon. They then penetrate the magnetosphere, where they are captured and completely ionized.

Quasi-stationary belt of protons and electrons

On March 22, 1991, a powerful flare occurred on the Sun, which was accompanied by the ejection of a huge mass of solar matter. It reached the magnetosphere by March 24 and changed its outer region. High-energy solar wind particles burst into the magnetosphere. They reached the area where CRESS, the American satellite, was then located. The instruments installed on it recorded a sharp increase in protons, the energy of which ranged from 20 to 110 MeV, as well as powerful electrons (about 15 MeV). This indicated the emergence of a new belt. At first, the quasi-stationary belt was observed on a number of spacecraft. However, only at the Mir station was it studied during its entire lifespan, which was about two years.

By the way, in the 60s of the last century, as a result of nuclear devices exploding in space, a quasi-stationary belt appeared, consisting of electrons with low energies. It existed for approximately 10 years. Radioactive fission fragments decayed, which was the source of charged particles.

Is there an RPZ on the Moon?

Our planet's satellite does not have the Van Allen radiation belt. In addition, it does not have a protective atmosphere. The surface of the Moon is exposed to solar winds. If it were strong, if it occurred during the lunar expedition, it would incinerate both the astronauts and the capsules, since a colossal flow of radiation would be released, which is fatal.

Is it possible to protect yourself from cosmic radiation?

This question has interested scientists for many years. In small doses, radiation is known to have virtually no effect on our health. However, it is only safe if it does not exceed a certain threshold. Do you know what level of radiation is outside the Van Allen Belt, on the surface of our planet? Typically, the content of radon and thorium particles does not exceed 100 Bq per 1 m 3. Inside the RPZ these figures are much higher.

Of course, the radiation belts of the Van Allen Earth are very dangerous for humans. Their effects on the body have been studied by many researchers. Soviet scientists in 1963 told Bernard Lovell, a famous British astronomer, that they did not know a means of protecting humans from exposure to radiation in space. This meant that even the thick-walled shells of Soviet devices could not cope with it. How did the thin metal, almost like foil, used in the American capsules protect the astronauts?

According to NASA, it sent astronauts to the Moon only when flares were not expected, which the organization is able to predict. This is what made it possible to reduce radiation danger to a minimum. Other experts, however, argue that it is only possible to approximately predict the date of large emissions.

Van Allen Belt and flight to the Moon

Leonov, a Soviet cosmonaut, did go into outer space in 1966. However, he was wearing a super-heavy lead suit. And just 3 years later, astronauts from the United States were jumping on the lunar surface, and obviously not in heavy spacesuits. Perhaps over the years, NASA specialists have managed to discover an ultra-light material that reliably protects astronauts from radiation? still raises many questions. One of the main arguments of those who believe that the Americans did not land on it is the existence of radiation belts.

The beginning of astronautics was marked by a number of discoveries, one of which was the discovery of the Earth's radiation belts. The Earth's inner radiation belt was discovered by American scientist James van Allen after the Explorer 1 flight. The Earth's outer radiation belt was discovered by Soviet scientists S. N. Vernov and A. E. Chudakov after the Sputnik-3 flight in 1958.

At some altitudes, the first satellites fell into areas that were densely saturated with charged particles with very high energy, sharply different from previously observed cosmic particles, both primary and secondary. After processing data from satellites, it became clear that we are talking about charged particles captured by the Earth's magnetic field.

It is known that any charged particles, once in a magnetic field, begin to “wrap” around the magnetic field lines, simultaneously moving along them. The dimensions of the turns of the resulting spiral depend on the initial speed of the particles, their mass, charge and the strength of the Earth's magnetic field in the region of near-Earth space into which they flew and changed the direction of movement.

The Earth's magnetic field is not uniform. At the poles it “condenses” - becomes denser. Therefore, a charged particle that has begun to move in a spiral along the magnetic line “ridden” by it from a region close to the equator, as it approaches any pole, experiences more and more resistance until it stops. And then it returns back to the equator and further to the opposite pole, from where it begins to move in the opposite direction. The particle finds itself, as it were, in a giant “magnetic trap” of the planet.

These regions of the magnetosphere, where high-energy charged particles (mainly protons and electrons) and particles with kinetic energy E less than critical accumulate and are retained, are called radiation belts. The Earth has three radiation belts, and now a fourth has been discovered. The Earth's radiation belt is a toroid.

The first such belt begins at an altitude of approximately 500 km above the western and 1500 km above the eastern hemisphere of the Earth. The largest concentration of particles in this belt - its core - is located at an altitude of two to three thousand kilometers. The upper limit of this belt reaches three to four thousand kilometers above the Earth's surface.

The second belt extends from 10-11 to 40-60 thousand km with a maximum particle density at an altitude of 20 thousand km.

The outer belt begins at an altitude of 60-75 thousand km.

The given boundaries of the belts are still only approximately determined and, apparently, change periodically within some limits.

These belts differ from each other in that the first of them, closest to the Earth, consists of positively charged protons with very high energy - about 100 Moe. Only the densest part of the Earth's magnetic field could capture and hold them. The flow of protons in it is quite stable over time and does not experience sharp fluctuations.

The second belt consists mainly of electrons with energies of “only” 30-100 keV. Larger flows of particles move in it than in the inner belt, and it experiences sharp fluctuations.

In the third belt, where the Earth's magnetic field is weakest, particles with an energy of 200 eV or more are retained.

In addition, electrons with energies less than 1 MeV fill almost the entire capture region. There is no division into belts for them; they are present in all three belts.

To understand how dangerous charged particles in radiation belts are for all life on Earth, let’s give an example for comparison. Thus, ordinary X-ray radiation, used briefly for medical purposes, has an energy of 30-50 keV, and powerful installations for x-raying huge ingots and blocks of metal - from 200 keV to 2 MeV. Therefore, the most dangerous for future cosmonauts and for all living things when flying to other planets are the first and second belts.

That is why scientists are now trying so hard and carefully to clarify the location and shape of these belts, and the distribution of particles in them. So far only one thing is clear. The corridors for habitable spacecraft to enter routes to other worlds will be areas close to the Earth's magnetic poles, free from high-energy particles.

The natural question is: where did all these particles come from? They are mainly thrown out from its depths by our Sun. It has now been established that the Earth, despite its enormous distance from the Sun, is located in the outermost part of its atmosphere. This, in particular, is confirmed by the fact that every time solar activity increases, and therefore the number and energy of particles emitted by the Sun increase, the number of electrons in the second radiation belt increases, which, as if under the pressure of the “wind” of these particles, is pressed towards Earth.

The separation of charges into layers and the formation of the Earth's radiation belts occurs under the influence of the acousto-magnetoelectric effect, which consists in the fact that short-wave radiation from the Sun, passing through the plasma across the lines of force of the Earth's magnetic field, sorts the charges according to their energy state into different levels. The presence of a certain number of charges in each layer, including on the surface of the Earth, gives reason to assume that the Earth, together with the entire atmosphere, can be considered as an electrical machine, which in design can be identified with a spherical multilayer, multi-rotor, asynchronous electrical capacitive-inductive machine.

Particles captured in the Earth's magnetic trap under the influence of the Lorentz force undergo oscillatory motion along a spiral trajectory along the magnetic field line from the Northern Hemisphere to the Southern Hemisphere and back. At the same time, the particles move more slowly (longitudinal drift) around the Earth.

When a particle moves in a spiral in the direction of increasing magnetic field (approaching the Earth), the radius of the spiral and its pitch decrease. The particle velocity vector, remaining unchanged in magnitude, approaches a plane perpendicular to the direction of the field. Finally, at a certain point (called a mirror point) the particle is “reflected”. It begins to move in the opposite direction - to the conjugate mirror point in the other hemisphere.

A proton with an energy of ~ 100 MeV completes one oscillation along the field line from the Northern Hemisphere to the Southern Hemisphere in a time of ~ 0.3 sec. The residence time (“life”) of such a proton in a geomagnetic trap can reach 100 years (~ 3×109 sec), during which time it can make up to 1010 oscillations. On average, captured high-energy particles make up to several hundred million oscillations from one hemisphere to the other.

Longitudinal drift occurs at a much lower speed. Depending on the energy, the particles make a full revolution around the Earth in a time from several minutes to a day. Positive ions drift westward, and electrons drift eastward. The motion of a particle in a spiral around a magnetic field line can be represented as consisting of a rotation about the so-called. instantaneous center of rotation and translational movement of this center along the line of force.

Van Allen radiation belt).

To a first approximation, the radiation belt is a toroid, in which two regions are distinguished:

an inner radiation belt at an altitude of ≈ 4000 km, consisting predominantly of protons with energies in the tens of MeV;
outer radiation belt at an altitude of ≈ 17,000 km, consisting predominantly of electrons with energies in the tens of keV.

The maximum intensity of low-energy protons is located at a distance of about 3 Earth radii from its center (approximately at an altitude of 12,500 km from the surface). Low-energy electrons fill the entire capture region. For them there is no division into internal and external belts. It is unusual to classify particles with energies of tens of keV as cosmic rays, but radiation belts are a single phenomenon and should be studied in conjunction with particles of all energies.

History of discovery

The existence of a radiation belt was first discovered by the American scientist James Van Allen in February 1958 when analyzing data from the American Explorer 1 satellite and was convincingly proven by recording periodically changing radiation levels during a full orbit of the Explorer satellite, specially modified by Van Allen to study the discovered phenomenon. 3". Van Allen's discovery was announced on May 1, 1958 and soon found independent confirmation in data from the Soviet Sputnik 3. A later re-analysis of data from the earlier Soviet Sputnik 2 showed that the radiation belts were also recorded by its equipment designed to analyze solar activity, but the strange readings of the solar sensor were then unable to be interpreted correctly. Soviet priority was also negatively affected by the lack of recording equipment on Sputnik (it was not provided on Sputnik 2, and it was broken on Sputnik 3), which is why the data obtained turned out to be fragmentary and did not give a complete picture of changes in radiation with altitude and the presence in near-Earth space of not just cosmic radiation, but a characteristic “belt” covering only certain altitudes. However, the more diverse equipment of Sputnik 3 helped clarify the “composition” of the inner belt. At the end of 1958, analysis of data from Pioneer 3 and the slightly later Luna 1 led to the discovery of the existence of an outer radiation belt, and American high-altitude nuclear explosions demonstrated that humans can influence the Earth's radiation belts. The analysis of these data led to the gradual formation, since mid-1959, of modern ideas about the existence of two radiation belts around the Earth and the mechanisms of their formation.

History of research

On August 30, 2012, two identical RBSP probes were launched from the Cape Canaveral Space Center using an Atlas V 410 rocket into a highly elliptical orbit with an apogee altitude of about 30 thousand kilometers Radiation Belt Storm Probes), designed to study radiation belts. They were subsequently renamed "Van Allen Probes" ( Van Allen Probes). Two devices were needed in order to distinguish changes associated with the transition from one region to another with changes occurring in the belts themselves. . One of the main results of this mission was the discovery of a third radiation belt, which appears for a short period of time on the order of a few weeks. As of February 2017, the operation of both probes continued.

Radiation belts of planets

Due to the presence of a strong magnetic field, the giant planets (Jupiter, Saturn, Uranus and Neptune) also have strong radiation belts, reminiscent of the Earth's outer radiation belt. Soviet and American space probes have shown that Venus, Mars, Mercury and the Moon do not have radiation belts.

History of research

Notes

Literature

Murzin S.V. Introduction to cosmic ray physics. - M.: Atomizdat, 1979.
Model of outer space: in 3 volumes. - M.: Moscow State University Publishing House, 1976.
Vernov S. N., Vakulov P. V., Logachev Yu. I. Radiation belts of the Earth // Achievements of the USSR in space research: collection. - M., 1968. - P. 106.
Space physics: trans. from English - M., 1966.
Tverskoy B. A. Dynamics of the Earth's radiation belts, - M., 1968.
Roederer H. Dynamics of radiation captured by the geomagnetic field: transl. from English - M., 1972.
Hess V. Radiation belt and magnetosphere: trans. from English - M., 1972.
Shabansky V. P. Phenomena in near-Earth space. - M., 1972.
Galperin Yu. I., Gorn L. S., Khazanov B. I. Measuring radiation in space. - M., 1972.
Adams, L.; Daly, E. J.; Harboe-Sorensen, R.; Holmes-Siedle, A. G.; Ward, A. K.; Bull, R. A. (December 1991). “Measurement of SEU and total dose in geostationary orbit under normal and solar flare conditions.” IEEE Transactions on Nuclear Science. 38 (6): 1686-1692.