Collection of CSE documents on the study of the Tunguska meteorite. Cosmic Dust is a special substance

SPACE MATTER ON THE EARTH'S SURFACE

Unfortunately, unambiguous criteria for the differentiation of cosmicchemical substance from formations close to it in shapeterrestrial origin has not yet been worked out. That's whymost researchers prefer to search for spacechemical particles in areas remote from industrial centers.For the same reason, the main object of research isspherical particles, most of the material havingirregular shape, as a rule, falls out of sight.In many cases, only the magnetic fraction is analyzed.spherical particles, according to which there are now the mostversatile information.

The most favorable objects for the search for spacedust is deep-sea precipitation / due to low speedsedimentation /, as well as polar ice floes, excellentpreserving all matter deposited from the atmosphere.facilities are practically free from industrial pollutionand are promising for the purpose of stratification, study of the distributionof cosmic matter in time and space. Bythe conditions of sedimentation are close to them and the accumulation of salt, the latter are also convenient in that they make it easy to isolatethe required material.

Searches for dispersedof space matter in peat deposits. It is known that the annual increase in high moor peatlands isapproximately 3-4 mm per year, and the only sourcemineral nutrition for vegetation of raised bogs ismatter falling out of the atmosphere.

Spacedust from deep-sea sediments

Peculiar red-colored clays and silts, foldedkami of siliceous radiolarians and diatoms, cover 82 million km 2ocean floor, which is one sixth of the surfaceour planet. Their composition according to S.S. Kuznetsov looks as follows as follows: 55% SiO 2 ;16% Al 2 O 3 ;9% F eO and 0.04% N i and Co, At a depth of 30-40 cm, fish teeth were found in it, alivein the Tertiary epoch, which gives reason to conclude thatsedimentation rate is approximately 4 cm per onea million years. In terms of terrestrial origin, the compositionclay is difficult to interpret.in them nickel and cobalt is the subject of numerousresearch and is considered to be related to the introduction of spacematerial / 2,154,160,163,164,179 /. Really,the nickel clarke is 0.008% for the upper horizons of the earthcrust and 10 % for sea water / 166 /.

Extraterrestrial matter found in deep-sea sedimentsfor the first time by Murray during the expedition on the "Challenger"/ 1873-1876 / / the so-called "space balls of Murray" /.A little later, Renard took up their research, as a resultwhat was the joint work on the description of the foundmaterial /141/. The detected space balls belong tosting to two types: metal and silicate. Both typespossessed magnetic properties, which made it possible to applya magnet to separate them from the sediment.

The spherulls had a regular round shape with an averagewith a diameter of 0.2 mm. Malleable was found in the center of the ball.an iron core covered with an oxide film on top.balls found nickel and cobalt, which made it possible to expressassumption about their cosmic origin.

Silicate spherulls, as a rule, do not have had strict sphereric form / they can be called spheroids /. Their size is slightly larger than metal, their diameter reaches 1 mm ... The surface has a scaly structure. Mineralogicalcue composition is very monotonous: they contain ironmagnesium silicates, olivines and pyroxenes.

Extensive material on the space component of deep-sea sediments collected by a Swedish expedition on a ship"Albatross" in 1947-1948 Its participants used selectioncolumns of soil to a depth of 15 meters, the study of the obtaineda number of works / 92,130,160,163,164,168 / are devoted to the material.The samples turned out to be very rich: Petterson points out that1 kg of sediment accounts for from several hundred to several thousand spherules.

All authors note a very uneven distributionballs both along the cut of the ocean floor and along itsarea. For example, Hunter and Parkin / 121 /, having examined twodeep-sea samples from different parts of the Atlantic Ocean,found that one of them contains almost 20 morespherula than the other. They attributed this difference to unequalsedimentation rates in different parts ocean.

In 1950-1952 the Danish deep-sea expedition usednile for collecting space matter in the bottom sediments of the ocean magnetic rake - an oak board withit has 63 strong magnets. With this device, about 45,000 m 2 of the ocean floor surface was combed.Among the magnetic particles with a probable cosmicorigin, two groups are distinguished: black balls with metalfacial nuclei or without them and brown balls with crystallinefacial structure; the first in size rarely exceed 0.2 mm , they are shiny, with a smooth or rough surfaceness. Among them there are fused specimensunequal sizes. The balls contain nickel andcobalt, magnetite and srey-berzite are common in mineralogical composition.

Balls of the second group have a crystal structureand have Brown color... Their average diameter is 0.5 mm ... These spherules contain silicon, aluminum and magnesium andhave numerous transparent inclusions of olivine orpyroxenes / 86 /. The question of the presence of balls in bottom sludgeThe Atlantic Ocean is also discussed in / 172a /.

Spacedust from soil and sediment

Academician Vernadsky wrote that cosmic matter is continuously deposited on our planet.a great opportunity to find him anywhere on earthsurface This is connected, however, with certain difficulties,which you can shine on to the following highlights:

1. the amount of substance falling out per unit area "very insignificantly;
2. conditions for the preservation of spherules for a longthe time has not yet been sufficiently studied;
3. there is the possibility of industrial and volcanic pollution;
4. it is impossible to exclude the role of redeposition of the already fallen outsubstances, as a result of which in some places there will bethere is an enrichment, and in others - impoverishment of space material.

Apparently optimal for the conservation of spacematerial is an oxygen-free environment, smoldering, in partnosti, place in deep-water basins, in areas of accumulationlation of sedimentary material with rapid burial of matter,as well as in marshes with a regenerative environment. Mostpossibly enrichment with space matter as a result of redeposition in certain parts of river valleys, where the heavy fraction of the mineral sediment is usually deposited/ here, obviously, only that part of the droppedsociety, specific gravity which is greater than 5 /. It is possible thatenrichment with this substance also takes place in the finalmoraines of glaciers, at the bottom of tarn lakes, in glacial pits,where the melt water accumulates.

In the literature there is information about the finds during the schlikhovspherules attributed to space / 6,44,56 /. In the atlasplacer minerals, published by the state publishing house of scientific and technicalliterature in 1961, spherules of this kind are attributed tometeorite.coy dust in ancient rocks. Works in this direction arehave recently been very intensively conducted by a number of studiestel. So, spherical hour types, magnetic, metal

and glassy, ​​the first with the appearance characteristic of meteoritesManstätten figures and high nickel content,described by Shkolnik in the Cretaceous, Miocene and Pleistocenerocks of California / 177,176 /. Later similar findswere made in Triassic rocks of northern Germany / 191 /.Croisier, setting himself the goal of studying spacecomponent of ancient sedimentary rocks, examined samplesfrom different places / area of ​​New York, New Mexico, Canada,Texas / and various ages / from the Ordovician to the Triassic inclusive /. The studied samples included limestones, dolomites, clays, shales. The author everywhere found spherules, which certainly cannot be attributed to the industrialstriation pollution, and, most likely, have a cosmic nature. Croisier claims that all sedimentary rocks contain cosmic material, and the number of spherules islebbles from 28 to 240 per gram. Particle size in mostin most cases, it fits in the range from 3µ to 40µ, andtheir number is inversely proportional to the size / 89 /.Data on meteoric dust in the Cambrian sandstones of EstoniaWijding reports / 16a /.

As a rule, spherules accompany meteorites and are foundin places of falls, along with meteorite debris. Previouslyin total, the balls were found on the surface of the Braunau meteorite/ 3 / and in the craters of Henbury and Wabar / 3 /, later similar formations along with a large number of particles of irregularforms were found in the vicinity of the Arizona crater / 146 /.This type of finely dispersed matter, as mentioned above, is usually referred to as meteorite dust. The latter was subjected to detailed study in the works of many studies.partners both in the USSR and abroad / 31,34,36,39,77,91,138.146.147.170-171.206 /. On the example of the Arizona spherulesit was found that these particles have an average size of 0.5 mmand consist of either Kamacite, germinated by goethite, or ofalternating layers of goethite and magnetite, covered with a thina layer of silicate glass with small inclusions of quartz.The content of nickel and iron in these minerals isis represented by the following numbers:

mineral iron nickel
kamasite 72-97% 0,2 - 25%
magnetite 60 - 67% 4 - 7%
goethite 52 - 60% 2-5%

Nininger / 146 / discovered in the Arizona balls a minerally characteristic of iron meteorites: cohenite, steatite,schreibersite, troilite. The nickel content was found to be equalon average, 1 7%, which coincides, in general, with the numbers , receivednym Reingard / 171 /. It should be noted that the distributionfine meteorite matter in the vicinityThe Arizona meteorite crater is very uneven.or an accompanying meteor shower. Mechanismthe formation of the Arizona spherules, according to Reinhardt, consists ofsudden solidification of liquid finely dispersed meteoritesubstances. Other authors / 135 /, along with this, assign a certaindivided place of condensation formed at the time of the fallvapors. Essentially similar results were obtained in the course of a studyof finely dispersed meteorite matter in the areafallout of the Sikhote-Alin meteor shower. E. L. Krinov/ 35-37,39 / subdivides this substance into the following main categories:

1. micrometeorites with a mass from 0.18 to 0.0003 g, havingregmaglipts and melting cortex / should be strictly distinguishedmicrometeorites according to E.L. Krinov from micrometeorites in the understandingNii Whipple, which was discussed above /;
2. meteoric dust - mostly hollow and porousmagnetite particles formed as a result of meteorite matter splashing in the atmosphere;
3. meteorite dust is a product of crushing of falling meteorites, consisting of sharp-angled debris. Into mineralogicalthe composition of the latter includes kamasite with an admixture of troilite, sreibersite and chromite.As in the case of the Arizona meteorite crater, the distributiondivision of matter by area is uneven.

Krinov considers spherules and other fused particles to be products of ablation of meteorites and cites as prooffinds of fragments of the latter with balls adhered to them.

Finds are also known at the site of the fall of a stone meteoriterain Kunashak / 177 /.

The issue of the distribution ofcosmic dust in soils and other natural objectsthe area of ​​the fall of the Tunguska meteorite. Great work in thisdirection were carried out in 1958-65 by expeditionsCommittee on Meteorites of the USSR Academy of Sciences of the Siberian Branch of the USSR Academy of Sciences. It was established thatin the soils of both the epicenter and places remote from it bydistance up to 400 km or more, are almost constantly detectedmetal and silicate balls ranging in size from 5 to 400 microns.Among them there are shiny, matte and roughhour types, regular beads and hollow cones. In somecases, metal and silicate particles are fused with each otherfriend. According to K.P. Florensky / 72 /, the soils of the epicentral area/ the Khushma - Kimchu interfluve / contain these particles only ina small amount / 1-2 per conventional unit of area /.Samples with a similar bead content are found ondistance up to 70 km from the crash site. Relative troubleThe nature of these samples is explained according to K.P. Florensky by thethe circumstance that at the moment of the explosion the bulk of the meteorologicalrita, turning into a finely dispersed state, was thrown outinto the upper atmosphere and then drifted in the directionwind. Microscopic parts, settling according to Stokes' law,should in this case form a scattering trail.Florensky believes that the southern border of the plume isabout 70 km to C З from the meteorite capture, in the poolthe Chuni river / area of ​​the Mutorai trading post / where the sample was foundwith the content of space balls up to 90 pieces per conditionalunit of area. In the future, according to the author, the traincontinues to stretch to the northwest, capturing the basin of the Taimura River.The works of the Siberian Branch of the Academy of Sciences of the USSR in 1964-65. found that relatively rich samples are found along the entire course R. Taimury, a also on N. Tunguska / see diagram /. The selected spherules contain up to 19% nickel / according to datamicrospectral analysis carried out at the Institute of Nuclearphysics of the Siberian Branch of the USSR Academy of Sciences /. This approximately coincides with the figuresobtained by P.N. Paley in the field on the model ofreiks isolated from the soils of the Tungu disaster area.These data allow us to assert that the found particleshave a truly cosmic origin. The question istheir relation to the Tunguska meteorite remains for nowwhich is open due to the lack of similar studiesin background regions, as well as the possible role of processesredeposition and secondary enrichment.

Interesting finds of spherules in the crater area on Patomskyhighlands. The origin of this formation, attributedHoop to volcanic, still controversial,since the presence of a volcanic cone in an area remotemany thousands of kilometers from volcanic foci, ancientthem and modern, in many kilometers of sedimentary-metamorphicstrata of the Paleozoic, it seems at least strange. Studies of spherules from the crater could provide an unambiguousthe answer to the question and about its origin / 82,50,53 /.the extraction of substances from soils can be carried out by the method ofhavaniya. In this way, a fraction of hundreds is allocated.microns and specific gravity above 5. However, in this casethere is a danger of discarding all the small magnetic tailcoattion and most of the silicate. E.L. Krinov advises to useMagnetic sizing with a magnet suspended from the bottom tray / 37 /.

A more accurate method is magnetic separation, dryor wet, although it also has a significant drawback: induring processing, the silicate fraction is lost.dry magnetic separation plants are described by Reinhardt / 171 /.

As already indicated, cosmic matter is often collectednear the surface of the earth, in areas free from industrial pollution. In their own direction, these works are close to the search for cosmic matter in the upper horizons of the soil.Trays filled withwater or adhesive solution, and plates lubricatedglycerin. The exposure time can be measured in hours, days,weeks depending on the purpose of the observation. At Dunlap Observatory in Canada,adhesive plates have been carried out since 1947/123 /. In LithuanianSeveral variants of methods of this kind are described in the table.For example, Hodge and Wright / 113 / have usedfor this purpose, slides covered with slowly dryingas an emulsion and, upon solidification, forming a ready-made dust preparation;Croisier / 90 / used ethylene glycol poured on trays,which was easily washed off with distilled water; in worksHunter and Parkin / 158 / oiled nylon mesh was used.

In all cases, spherical particles were found in the sediment,metal and silicate, most often smaller in size 6 µ in diameter and rarely exceeding 40 µ.

Thus, the totality of the presented dataconfirms the assumption that it is in principle possibledetection of space matter in soil practically onany part of the earth's surface. At the same time, it followskeep in mind that using soil as an objectto identify the space component is associated with methodologicaldifficulties far exceeding those in relation tosnow, ice and possibly bottom silt and peat.

Cosmicsubstance in ice

According to Krinov / 37 /, the detection of space matter in the polar regions is of significant scientific importance.because in this way a sufficient amount of material can be obtained, the study of which will probably bringsolution of some geophysical and geological issues.

The release of cosmic matter from snow and ice canto be carried out different methods starting from collectionlarge fragments of meteorites and ending with obtaining from thawedwater of mineral sediment containing mineral particles.

In 1959. Marshall / 135 / suggested an ingenious wayanalysis of particles from ice, similar to the counting methodred blood cells in the bloodstream. Its essence ismeans that the water obtained by melting the sampleice, electrolyte is added and the solution is passed through a narrow hole with electrodes on both sides. Atthe passage of a particle, the resistance changes sharply in proportion to its volume. Changes are recorded using specialgod recording device.

It should be borne in mind that ice stratification nowcarried out in several ways. It is possible thatcomparison of already stratified ice with distributionspace matter may open up new approachesstratification in places where other methods cannot beapplied for one reason or another.

For collecting space dust, American Antarcticexpeditions 1950-60 used cores obtained atdetermining the thickness of the ice cover by drilling. / 1 S3 /.Samples with a diameter of about 7 cm were sawn into pieces according to 30 cm length, melted and filtered. The resulting precipitate was carefully examined under a microscope. Have been discoveredparticles both spherical and irregular shape, andthe former made up an insignificant part of the sediment. Further research was limited only to spherules, since theycould be more or less confidently classified as a spacecomponent. Among the balls from 15 to 180 / h wereparticles of two types were found: black, shiny, strictly spherical and brown transparent.

Detailed study of cosmic particles isolated fromice of Antarctica and Greenland, was undertaken by Hodgeand Wright / 116 /. In order to avoid industrial pollutionice was taken not from the surface, but from a certain depth -in Antarctica, a 55-year layer was used, and in Greenland -750 years ago. For comparison, particles were selectedfrom the air of Antarctica, which turned out to be similar to glacial ones. All particles fit into 10 classification groupswith a sharp division into spherical particles, metallicand silicate, with and without nickel.

An attempt to obtain space balls from a high-mountainoussnow undertaken by Divari / 23 /. Having melted a significant volumesnow / 85 buckets / taken from the surface of 65 m 2 on the glacierTuyuk-Su in the Tien Shan, however, he did not get what he wantedresults that can be explained or uneventhe fallout of cosmic dust onto the earth's surface, orfeatures of the applied technique.

In general, it seems that the collection of cosmic matter inpolar regions and on high mountain glaciers is oneof the most promising areas of work in space dust.

Sources of pollution

Currently, two main sources of material are known -la, which can imitate in its properties spacedust: volcanic eruptions and industrial wasteenterprises and transport. It is known what volcanic dustemitted during eruptions into the atmosphere, canstay suspended there for months and years.By virtue of structural features and a small specificweight this material can be distributed globally, andin the process of transfer, the particles are differentiated with respect toweight, composition and size, which must be taken into account whenspecific analysis of the situation. After the famous eruptionthe Krakatoa volcano in August 1883, the finest dust emittedto a height of up to 20 km. was found in the air infor at least two years / 162 /. Similar observationsdenii were made during periods of volcanic eruptions at Mont Pele/ 1902 /, Katmay / 1912 /, groups of volcanoes in the Cordilleras / 1932 /,volcano Agung / 1963 / / 12 /. Microscopically collected dustfrom different regions of volcanic activity, has the formgrains of irregular shape, with curvilinear, broken,rugged contours and relatively rarely spheroidaland spherical with a size from 10µ to 100. The number of sphericaldov is only 0.0001% by weight of the total material/ 115 /. Other authors raise this value to 0.002% / 197 /.

Volcanic ash particles are black, red, greenflaky, gray or brown. Sometimes they are colorlesstransparent and reminiscent of glass. Generally speaking, in volcanicIn some products, glass is an essential part. itconfirmed by the data of Hodge and Wright, who found thatparticles with iron content from 5% and above arenear volcanoes only 16% . It should be borne in mind that in the processdust transfer, it is differentiated in size andspecific gravity, and large dust particles are sifted out faster Total. As a result, in remote from volcaniccenters of areas, it is likely that only the smallest and light particles.

Spherical particles were subjected to special studyvolcanic origin. It has been found that they possessmost often an eroded surface, shape, roughlicking to spherical, but never elongatedneck, like particles of meteorite origin.It is very significant that they do not have a kernel folded cleaniron or nickel, like those balls that are consideredspace / 115 /.

The mineralogical composition of volcanic balls containsa significant role belongs to glass, which has a bubblystructure, and iron-magnesium silicates - olivine and pyroxene. A much smaller part of them is composed of ore minerals - pyri-volume and magnetite, which for the most part form disseminatednicknames in glass and frame structures.

As for the chemical composition of volcanic dust, thenan example is the composition of the ashes of Krakatoa.Murray / 141 / found it high in aluminum/ up to 90% / and low iron content / not exceeding 10%.It should be noted, however, that Hodge and Wright / 115 / could notconfirm Morrey's data on aluminum.volcanic spherules are also discussed in/ 205a /.

Thus, the properties characteristic of volcanicmaterials can be summarized as follows:

1. volcanic ash contains a high percentage of particlesirregular and low - spherical,
2. balls of volcanic rock have certain structurestouristic features - eroded surfaces, the absence of hollow spherules, often bubbling,
3. porous glass predominates in the composition of spherules,
4. the percentage of magnetic particles is low,
5. in most cases, the spherical shape of the particles imperfect
6. acute-angled particles have sharply angular shapesrestrictions, which allows them to be used asabrasive material.

A very significant danger of imitation of space sphereswheel with industrial balls, in large quantitiesremovable steam locomotive, steamboat, factory pipes, formed during electric welding, etc. Specialstudies of such objects have shown that a significantthe percentage of the latter is in the form of spherules. According to the Schoolboy / 177 /,25% industrial products are piled up with metal slag.He also gives the following classification of industrial dust:

1. balls non-metallic, irregular shape,
2. balls are hollow, very shiny,
3. balls, similar to space, folded metalmaterial with the inclusion of glass. Among the latter,most common, there are teardrop-shaped,cones, double spherules.

From the point of view of interest to us, the chemical compositionindustrial dust was studied by Hodge and Wright /115/.updated that characteristic features its chemical compositionis high iron content and in most cases nickel free. It must be borne in mind, however, that neitherone of these signs cannot serve as absolutedistinction criterion, especially since the chemical composition of differenttypes of industrial dust can be varied, andforesee in advance the appearance of this or that variety ofindustrial spherules are almost impossible. Therefore, the best can serve as a guarantee against confusion at the modern levelknowledge only sampling in remote "sterile" fromindustrial pollution areas. Industrial degreepollution, as shown by special studies, isin direct proportion to the distance to settlements.Parkin and Hunter in 1959 made observations as possibletransportation of industrial spherules with water / 159 /.Although balls with a diameter of more than 300µ were emitted from factory pipes, in a water basin located 60 miles from the cityyes in the direction of the prevailing winds, onlysingle copies, size 30-60, number of copies-the ditch 5-10µ in size was, however, significant. Hodge andWright / 115 / showed that in the vicinity of the Yale observatory,near the city center, per day 1 cm 2 of the surface fellup to 100 balls with a diameter of more than 5µ... Their double the amountdecreased on Sundays and fell 4 times at a distancenii 10 miles from the city. So in remote areasprobably industrial pollution only by balls of diameter rum less than 5 µ .

It should be borne in mind that in recent20 years ago there was a real danger of food contaminationnuclear explosions "which can supply spherules to the globalnominal scale / 90,115 /. These products differ from yesradioactivity and the presence of specific isotopes -strontium - 89 and strontium - 90.

Finally, it should be borne in mind that some contaminationatmosphere with products similar to meteoric and meteoritedust, may be caused by combustion in the Earth's atmosphereartificial satellites and launch vehicles. Phenomena observedin this case are very similar to what takes place forloss of fireballs. Serious danger to scientific researchcosmic matter represent irresponsibleexperiments implemented and planned abroad withlaunching into near-earth spacepersistent substance of artificial origin.

The formand physical properties of cosmic dust

Shape, specific gravity, color, luster, fragility and other physicalThe chemical properties of cosmic dust found in various objects have been studied by a number of authors. Some-ry researchers have proposed schemes for the classification of spacedust based on its morphology and physical properties.Although a single unified system has not yet been developed,it seems, however, useful to cite some of them.

Baddhyu / 1950 / / 87 / based on purely morphologicalfeatures has divided terrestrial matter into the following 7 groups:

1. irregular gray amorphous debris 100-200 µ.
2. slag-like or ash-like particles,
3. rounded grains, like fine black sand/magnetite/,
4. smooth black shiny balls with an average diameter 20µ .
5. large black balls, less shiny, often roughrather thin, rarely exceeding 100 µ in diameter,
6. silicate balls from white to black, sometimeswith gas inclusions,
7. dissimilar balls consisting of metal and glass,with an average size of 20µ.

All the variety of types of cosmic particles, however, are notis limited, apparently, by the listed groups.So, Hunter and Parkin / 158 / found in the air roundedflattened particles, apparently of cosmic origin which cannot be attributed to any of thenumerical classes.

Of all the groups described above, the most accessible foridentification by appearance 4-7, having the form of correct balls.

E.L. Krinov, studying the dust collected in the SikhoteAlin fall, distinguished in its composition the wrongin the form of fragments, balls and hollow cones / 39 /.

Typical shapes of cosmic balls are shown in Fig. 2.

A number of authors classify space matter according toa set of physical and morphological properties. By lotspace matter is usually divided into 3 groups/86/:

1. metal, consisting mainly of iron,with a specific gravity of more than 5 g / cm 3.
2. silicate - transparent glass particles with a specificweighing about 3 g / cm 3
3. heterogeneous: metal particles with glass inclusions and glass particles with magnetic inclusions.

Most researchers remain within thisrough classification, limited to only the most obviousfeatures of difference. However, those that deal withparticles extracted from the air, distinguish another group -porous, brittle, with a density of about 0.1 g / cm 3/129 /. TOthese include meteor shower particles and most bright sporadic meteors.

A fairly comprehensive classification of particles detectedin Antarctic and Greenland ice, as well as capturedfrom the air, given by Hodge and Wright and presented in the diagram / 205 /:

1. black or dark gray dull metal balls,pitted, sometimes hollow;
2. black, glassy, ​​highly refractive balls;
3. light, white or coral, glassy, ​​smooth,sometimes translucent spherules;
4. particles of irregular shape, black, shiny, brittle,granular, metal;
5. irregularly shaped reddish or orange, dull,uneven particles;
6. irregular, pinkish orange, dull;
7. irregular, silvery, shiny and dull;
8. irregular, multi-colored, brown, yellow, green, black;
9. irregular, transparent, sometimes green orblue, glassy, ​​even, with sharp edges;
10. spheroids.

Although the classification of Hodge and Wright seems to be the most complete, nevertheless, particles are often found that, judging by the descriptions of various authors, are difficult to attribute toto one of the named groups. Thus,elongated particles, balls adhered to each other, balls,having various growths on their surface / 39 /.

On the surface of some spherules in a detailed studythere are figures similar to the Widmanstätten, observedat iron-nickel meteorites / 176 /.

The internal structure of the spherules does not differ greatlyimage. Based on this feature, the following can be distinguished 4 groups:

1. hollow spherules / meet with meteorites /,
2. metal spherules with a core and an oxidized shell/ in the core, as a rule, nickel and cobalt are concentrated,and in the shell - iron and magnesium /,
3. uniformly oxidized balls,
4. silicate balls, most often homogeneous, with flakethat surface, with metal and gas inclusions/ the latter give them the appearance of slags or even foam /.

As for the size of particles, there is no firmly established division on this basis, and each authoradheres to its classification depending on the specifics of the available material. The largest of the described spherules,found in deep-sea sediments by Brown and Pauli / 86 / in 1955, hardly exceed 1.5 mm in diameter. itclose to the present limit found by Epic / 153 /:

where r - particle radius, σ - surface tensionmelt, ρ is the air density, and v - drop speed. Radius

particles cannot exceed a certain limit, otherwise the dropis split into smaller ones.

The lower limit is most likely not limited, which follows from the formula and is justified in practice, becauseas the techniques improve, the authors operate on allsmaller particles. Most researchers limitthe lower limit is 10-15µ /160-168.189/.time started to study particles with a diameter of up to 5 µ / 89 / and 3 µ / 115-116 /, and Hemenway, Fulman and Phillips operateparticles up to 0.2 / µ and smaller in diameter, highlighting them in particularthe first class of nanameteorites / 108 /.

The average particle diameter of cosmic dust is taken equal to 40-50 µ. As a result of intensive study of spacewhom substances from the atmosphere did the Japanese authors find that 70% the total material is particles less than 15 µ in diameter.

In a number of works / 27,89,130,189 / there is a statement aboutthe fact that the distribution of balls depending on their massand the size obeys the following pattern:

V 1 N 1 = V 2 N 2

where v - ball mass, N - number of balls in a given groupThe results, which are in satisfactory agreement with the theoretical ones, were obtained by a number of researchers who worked with spacematerial isolated from various objects / for example, Antarctic ice, deep-sea sediments, materials,obtained as a result of satellite observations /.

Of fundamental interest is the question of whetherto what extent the properties have changed over the course of geological history. Unfortunately, the material accumulated at present does not allow us to give an unambiguous answer, however,the attention of the Shkolnik's message / 176 / about classificationspherules isolated from the Miocene sedimentary rocks of California. The author has divided these particles into 4 categories:

1 / black, strongly and weakly magnetic, solid or with cores consisting of iron or nickel with an oxidized shellCoy of silica with an admixture of iron and titanium. These particles can be hollow. Their surface is intensely shiny, polished, in some cases rough or iridescent as a result of light reflection from saucer-shaped depressions on their surfaces,

2/ steel gray or bluish gray, hollow, thinwall, very fragile spherules; contain nickel, havepolished or smoothed surface;

3 / fragile balls containing numerous inclusionsgray steel metallic and black non-metallicmaterial; there are microscopic bubbles in their walls ki / this group of particles is the most numerous /;

4 / brown or black silicate spherules, non-magnetic.

It is easy to replace that the first group for the Schoolboyclosely corresponds to 4 and 5 groups of particles according to Baddhy.number of these particles, there are hollow spherules similar tothose that are found in areas of meteorite falls.

Although this data does not contain comprehensive informationon the issue raised, it seems possible to expressin the first approximation, the opinion that morphology and physi-physical properties of at least some groups of particlesof cosmic origin, falling on the Earth, did not undergohave been singing significant evolution over the course of the availablegeological study of the period of the planet's development.

Chemicalcomposition of space dust.

The study of the chemical composition of cosmic dust meetswith certain difficulties in principle and technicalcharacter. On my own small size of the studied particles,the difficulty of obtaining in any significant amountwax create significant obstacles to the application of techniques widely used in analytical chemistry. Further,it should be borne in mind that the samples under study in the overwhelming majority of cases may contain impurities, and sometimesvery significant, terrestrial material. Thus, the problem of studying the chemical composition of cosmic dust isit raises the question of its differentiation from terrestrial impurities.Finally, the very formulation of the question of the differentiation of the "earthly"and the "cosmic" substance is to some extent conditional, because The earth and all the components that make up it,ultimately also represent a space object, andtherefore, strictly speaking, it would be more correct to pose the questionon finding signs of difference between different categoriescosmic matter. It follows that the similarity isa society of terrestrial and extraterrestrial origin can, in principle,extend very far, which creates additionaldifficulties in studying the chemical composition of cosmic dust.

However, in recent years, science has been enriched by a number ofmethodological techniques that allow, to a certain extent, to transformtop up or go around obstacles that arise. Development of newthe latest methods of radiation chemistry, X-ray structuralmicroanalysis, improvement of microspectral techniques now make it possible to study insignificant in theirthe size of the objects. Currently, it is quite affordableanalysis of the chemical composition of not only individual particles of cos-dust, but also the same particle in different its plots.

In the last decade, a significant number ofworks devoted to the study of the chemical composition of spacedust emitted from various sources. For reasonswhich we have already touched on above, the study was mainly made of spherical particles related to magnetdust fraction, As with the characteristics of physicalproperties, our knowledge of the chemical composition of acute-angledthe material is still completely inadequate.

Analyzing the materials obtained in this direction as a wholea number of authors, one should come to the conclusion that, firstly,the same elements are found in cosmic dust as inother objects of terrestrial and space origin, so, it contains Fe, Si, Mg .In some cases - rarelyland elements and Ag finds are doubtful /, in relation tothere is no reliable information in the literature. Secondly, the wholethe totality of cosmic dust falling to Earth couldit is divided by chemical composition, at least by tThree large groups of particles:

a) metal particles with a high content Fe and N i,
b) particles of predominantly silicate composition,
c) particles of mixed chemical nature.

It is easy to see that the listed three groups, according toessentially coincide with the accepted qualification of meteorites that ukrefers to a close, or maybe a common source ofcirculation of both types of cosmic matter. It can be noted dFurther, there is a wide variety of particles within each of the groups under consideration. This gives rise to a number of researchersit divides cosmic dust by chemical composition by 5.6 andmore groups. So, Hodge and Wright distinguish the following eight tonstypes of the main particles, which differ from each other as torphological characteristics and chemical composition:

1. iron balls with the presence of nickel,
2. iron spherules, in which nickel is not found,
3. silicate balls,
4. other spherules,
5. irregularly shaped particles with a high liquid content iron and nickel;
6. the same without the presence of any significant quantities food of nickel,
7. silicate particles of irregular shape,
8. other particles of irregular shape.

The above classification implies, among other things,that circumstance that the presence of a high content of nickel in the material under study cannot be recognized as an obligatory criterion of its cosmic origin. So, meaningMost of the material extracted from the ice of Antarctica and Greenland, collected from the air of the high mountain regions of New Mexico and even from the area of ​​the fall of the Sikhote-Alin meteorite did not contain quantities available for determinationnickel. At the same time, one has to take into account the very well-founded opinion of Hodge and Wright that a high percentage of nickel / in some cases up to 20% / is the onlya reliable criterion for the cosmic origin of a particular particle. Obviously, in his absence, the researchershould not be guided by the search for "absolute" criteria "and to assess the properties of the material under study, taken in their the aggregate.

In many works, the inhomogeneity of the chemical composition of even the same particle of space material in different parts of it is noted. It has been established that nickel gravitates towards the core of spherical particles, and cobalt is also found there.The outer shell of the ball is composed of iron and its oxide.Some authors assume that nickel exists in the formindividual spots in the magnetite substrate. Below we giveaverage grade digital materialsnickel in dust of cosmic and terrestrial origin.

It follows from the table that the analysis of the quantitative contentnickel may be useful in differentiatingcosmic dust from volcanic.

From the same point of view, the ratios N i : Fe ; Ni : Co, Ni: Cu which are sufficientlyconstant for individual objects of the earth and space origin.

igneous rocks-3,5 1,1

When differentiating cosmic dust from volcanicand industrial pollution a certain benefit canalso provide study of quantitative content Al and K which are rich in volcanic foods, and Ti and V, which are frequent companions Fe in industrial dust.It is very important that in some cases industrial dust can contain a high percentage of N i ... Therefore, the criterion for distinguishing some types of cosmic dust fromEarth should serve more than just high N i, a high content N i together with Co and C u / 88,121,154,178,179 /.

Information on the presence of radioactive products of cosmic dust is extremely scarce. Report negative resultstatah testing cosmic dust for radioactivity thatseems questionable in view of the systematic bombingdistributions of dust particles in interplanetary spacestate, cosmic rays. As a reminder, products are targetednoisy cosmic radiation have been repeatedly detected in meteorites.

Dynamicsspace dust fallout in time

According to the hypothesis Paneth / 156 /, meteorite falloutdid not take place in distant geological epochs / earlierquaternary time /. If this opinion is correct, thenit should apply to cosmic dust, or althoughto that part of it, which we call meteorite dust.

The main argument in favor of the hypothesis was the lack ofthe result of finds of meteorites in ancient rocks, at presenttime, however, is available whole line finds like meteorites,and the cosmic dust component in geologicalformations of rather ancient age / 44.92,122,134,176-177 /, Many of the listed sources are citedabove, it should be added that Mach / 142 / found balls,apparently of cosmic origin in the Siluriansalts, and Croisier / 89 / found them even in the Ordovician.

The distribution of spherules along the section in deep-water sediments was studied by Petterson and Rothsha / 160 /, who discoveredlived that nickel was unevenly distributed throughout the cut, whichexplained, in their opinion, by cosmic reasons. Laterfound to be the richest in space materialthe youngest layers of bottom silts, which, apparently, is due towith the gradually occurring processes of destruction of cosmicwhom substance. In this regard, it is natural to assumethe idea of ​​a gradual decrease in the concentration of cosmicsubstances down the section. Unfortunately, in the literature available to us, we have not come across sufficiently convincing data suchof the city, the available reports are sketchy. So, Shkolnik / 176 /found an increased concentration of balls in the weathering zoneformation of Cretaceous deposits, from this fact he wasa well-founded conclusion was made that the spherules, apparently,can withstand harsh conditions if theycould have undergone laterization.

Modern regular studies of space falloutdust show that its intensity changes significantly day by day / 158 /.

Apparently, there is a certain seasonal dynamics / 128,135 /, and the maximum intensity of falloutfalls in August-September, which is associated with meteoricstreams /78,139/,

It should be noted that meteor showers are not the onlythe main reason for the massive fallout of cosmic dust.

There is a theory that meteor showers cause precipitation / 82 /, meteoric particles in this case are condensation nuclei / 129 /. Some authors have suggestedThey want to collect cosmic dust from rainwater and offer their own devices for this purpose / 194 /.

Bowen / 84 / found that the peak of precipitation is laggingfrom the maximum meteoric activity by about 30 days, which can be seen from the following table.

Although these data are not generally accepted, howeverthey deserve some attention. Bowen's findings are confirmedare based on material from Western Siberia by Lazarev / 41 /.

Although the question of seasonal dynamics fallout of spacedust and its connection with meteor showers is not completelyresolved, there is good reason to believe that such a pattern takes place. So, Croisier / CO /, based onfive-year systematic observations, suggests that two maxima of cosmic dust fallout,that took place in the summer of 1957 and 1959, correlate with meteormi streams. Summer high confirmed by Morikubo, seasonaldependence was also noted by Marshall and Craiken / 135,128 /.It should be noted that not all authors are inclined to attribute theseasonal dependence due to meteoric activity/ for example, Brier, 85 /.

With regard to the distribution curve of daily precipitationmeteoric dust, it seems to be strongly distorted by the influence of winds. This, in particular, is reported by Kizilermak andCroisier / 126.90 /. A good summary of thisquestion is available at Reinhardt / 169 /.

Distributioncosmic dust on the surface of the earth

The question of the distribution of cosmic matter on the surfacethese Earth, like a number of others, has been developed completely inadequatelyexactly. Opinions as well as factual material reportedvarious researchers are very contradictory and incomplete.One of the most prominent specialists in this field, Petterson,definitely expressed the opinion that cosmic matterdistributed on the surface of the Earth is extremely uneven / 163 /. NSthen, however, contradicts a number of experimentaldata. In particular, de Jaeger /123/, based on feescosmic dust produced by sticky plates near the Canadian observatory Dunlap claims that cosmic matter is distributed fairly evenly over large areas... A similar opinion was expressed by Hunter and Parkin / 121 / based on the study of space matter in the bottom sediments of the Atlantic Ocean. Walking / 113 / conducted research of cosmic dust at three points distant from each other. The observations were carried out for a long time, for a whole year. An analysis of the results obtained showed the same rate of accumulation of matter at all three points, and on average, about 1.1 spherules fell out per 1 cm 2 per day.about three microns in size. Research in this direction were continued in 1956-56. Hodge and Wildt / 114 /. Onthis time, the collection was carried out in areas set apart fromfriend over very long distances: in California, in Alaska,In Canada. Average number of spherules calculated , per unit surface, which turned out to be 1.0 in California, 1.2 in Alaska, and 1.1 spherical particles in Canada forms for 1 cm 2 per day. Distribution of spherules by sizewas approximately the same for all three points, and 70% were formations with a diameter of less than 6 microns, the numberparticles larger than 9 microns in diameter were small.

It can be assumed that, apparently, the fallout of the cosmicdust goes to the Earth, in general, quite evenly, against this background, certain deviations from general rule... So, one can expect the presence of a certain latitudinalthe effect of the fallout of magnetic particles with a tendency to concentratetions of the latter in the polar regions. Further, it is known thatthe concentration of finely dispersed cosmic matter canbe elevated in areas of large meteorite masses/ Arizona meteorite crater, Sikhote-Alin meteorite,possibly the area of ​​the fall of the Tunguska space body /.

Primary uniformity can, however, in the futurebe significantly disturbed as a result of secondary redistributionfission of matter, and in some places it can haveaccumulation, and in others - a decrease in its concentration. In general, this issue is very poorly developed, but preliminaryexpedition data K M ET AS USSR / head K.P. Florensky / / 72/ let us talk aboutthe fact that, at least in some cases, the content of spacechemical substance in the soil can fluctuate over a wide range lah.

Migratsand Ispacesubstancesvbiogenosfere

Contradictory as the estimates of the total amount of spacechemical matter that falls annually on the Earth, it is possible withto say one thing with certainty: it is measured in many hundredsthousands, and maybe even millions of tons. Absolutelyit is obvious that this huge mass of matter is included in the distanceNeighborhood in a complex chain of processes of circulation of matter in nature, which constantly takes place within the framework of our planet.Cosmic matter thus becomes a compositepart of our planet, literally - earthly matter,which is one of the possible channels of influence of spaceenvironment on the biogenosphere. From this point of view, the problemcosmic dust was of interest to the founder of modernbiogeochemistry ac. Vernadsky. Sorry, work in thisdirection, in fact, has not yet been seriously started. Thereforewe are forced to confine ourselves to only stating a fewfacts that seem to be related to the affectedThere are a number of NATO indications that deep seasediments remote from the sources of material drift and havinglow accumulation rate, relatively rich in Co and Cu.Many researchers ascribe to these elements cosmicsome origin. Apparently, various types of cosmic particleschemical dust at different rates are included in the cycle of substances in nature. Some types of particles are very conservative in this respect, as evidenced by the finds of magnetite balls in ancient sedimentary rocks.the variation of particles can obviously depend not only on theirnature, but also on conditions environment in particularthe values ​​of its PH.V the highest degree it is likely that the elementsfalling to Earth as part of cosmic dust, may infurther included in the composition of plants and animalsorganisms that inhabit the Earth. In favor of this assumptionsay, in particular, some data on the chemical compositionvegetation in the area of ​​the fall of the Tunguska meteorite.All this, however, is only the first outline,the first attempts to approach not so much a solution as toposing the question in this plane.

Recently, there has been a tendency for even greater estimates of the probable mass of the falling cosmic dust. Fromefficient researchers estimate it at 2.410 9 tons / 107a /.

Perspectivesstudying cosmic dust

Everything that was said in the previous sections of the work,allows us to talk about two things with sufficient reason:first, that the study of cosmic dust is seriouslyis just beginning and, secondly, that the work in this sectionscience turns out to be extremely fruitful for solvingmany questions of theory / in the future, maybe forpractices /. A researcher working in this field attractedfirst of all, a huge variety of problems, one way orotherwise related to clarifying the relationship in the system Earth is space.

How it seems to us further development teachings aboutcosmic dust should go mainly along the following main directions:

1. The study of the near-Earth dust cloud, its spacelocation, properties of dust particles includedin its composition, sources and ways of its replenishment and loss,interaction with radiation belts.can be carried out in full with missiles,artificial satellites, and later - interplanetaryships and automatic interplanetary stations.
2. Of undoubted interest for geophysics is cosmchemical dust entering the atmosphere at altitude 80-120 km, in in particular, its role in the mechanism of occurrence and developmentsuch phenomena as the glow of the night sky, a change in polaritydaylight fluctuations, transparency fluctuations atmosphere, development of noctilucent clouds and light stripes of Goffmeister,young and crepuscular phenomena, meteor events in atmosphere Earth. Special it is of interest to study the degree of correlationlations between the listed phenomena. Unexpected aspects
cosmic influences can be revealed, apparently, infurther study of the relationship between processes havingplace in the lower atmosphere - troposphere, with penetratingin the last space matter. The most seriousattention should be paid to testing Bowen's hypothesis ofconnection of precipitation with meteor showers.
3. Of undoubted interest for geochemists isstudy of the distribution of space matter on the surfaceEarth, the impact on this process of specific geographic,climatic, geophysical and other conditions inherent
this or that area of ​​the globe. Until now completelythe question of the impact of magnetic field Earth on processaccumulation of cosmic matter, meanwhile, in this area,there are likely to be interesting finds, especiallyif you build your studies taking into account paleomagnetic data.
4. Of fundamental interest to both astronomers and geophysicists, not to mention general cosmogonists,has a question about meteoric activity in remote geologicalepochs. Materials that will be obtained during this
works can probably be used in the futureto develop complementary methods stratificationbottom, glacial and silent sedimentary deposits.
5. An essential area of ​​work is the studymorphological, physical, chemical properties of spacecomponent of the earth's precipitation, development of methods for distinguishing braidsdust from volcanic and industrial, researchisotopic composition of cosmic dust.
6. Searches for organic compounds in cosmic dust.It seems likely that the study of cosmic dust will contribute to the solution of the following theoretical questions:

1. The study of the process of evolution of cosmic bodies, in particularness, the Earth and the solar system as a whole.
2. The study of the movement, distribution and exchange of spacematter in the solar system and the galaxy.
3. Clarification of the role of galactic matter in the solar system.
4. Study of the orbits and velocities of cosmic bodies.
5. Development of the theory of interaction of space bodies with the Earth.
6. Deciphering the mechanism of a number of geophysical processesin the Earth's atmosphere, undoubtedly associated with space phenomena.
7. The study possible ways cosmic influences onbiogenosphere of the Earth and other planets.

It goes without saying that the development of even those problemswhich are listed above, but they are far from being exhaustedthe whole range of issues related to cosmic dust,is possible only under the condition of wide complexing and combiningthe efforts of specialists of various profiles.

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Cosmic dust, its composition and properties are little known to a person who is not associated with the study of extraterrestrial space. However, such a phenomenon leaves its traces on our planet! Let us consider in more detail where it comes from and how it affects life on Earth.

Space dust concept

Space dust on Earth is most often found in certain layers of the ocean floor, ice sheets of the polar regions of the planet, peat deposits, inaccessible places in the desert and meteorite craters. The size of this substance is less than 200 nm, which makes its study problematic.

Usually the concept of cosmic dust includes the demarcation of interstellar and interplanetary varieties. However, all this is very conditional. The most convenient option for studying this phenomenon is considered to be the study of dust from space at the boundaries Solar system or beyond.

The reason for such a problematic approach to the study of the object is that the properties of extraterrestrial dust change dramatically when it is near a star like the Sun.

Theories of the origin of cosmic dust

Streams of cosmic dust constantly attack the Earth's surface. The question arises where this substance comes from. Its origins give rise to many discussions among experts in this field.

There are such theories of the formation of cosmic dust:

• Decay of celestial bodies... Some scientists believe that cosmic dust is nothing more than the result of the destruction of asteroids, comets and meteorites.
• The remnants of a cloud of protoplanetary type... There is a version according to which cosmic dust is attributed to microparticles of a protoplanetary cloud. However, this assumption raises some doubts due to the fragility of the finely dispersed substance.
• The result of an explosion on the stars... As a result of this process, according to some experts, a powerful release of energy and gas occurs, which leads to the formation of cosmic dust.
• Residual phenomena after the formation of new planets... The so-called construction waste has become the basis for the generation of dust.

According to some studies, a certain part of the constituent of cosmic dust arose before the formation of the solar system, which makes this substance even more interesting for further study. This is worth paying attention to when evaluating and analyzing such an extraterrestrial phenomenon.

The main types of space dust

There is currently no specific classification of the types of cosmic dust. It is possible to distinguish between subspecies by visual characteristics and the location of these microparticles.

Consider seven groups of cosmic dust in the atmosphere, differing in external indicators:

1. Irregular gray debris. These are residual phenomena after a collision of meteorites, comets and asteroids with a size of no more than 100-200 nm.
2. Particles of cinder-like and ash-like formation. Such objects are difficult to identify solely by external signs, because they have undergone changes after passing through the Earth's atmosphere.
3. The grains are round in shape, which are similar in parameters to black sand. Outwardly, they resemble magnetite powder (magnetic iron ore).
4. Small black circles with a characteristic luster. Their diameter does not exceed 20 nm, which makes their study a painstaking task.
5. Larger balls of the same color with a rough surface. Their size reaches 100 nm and allows a detailed study of their composition.
6. Balls of a certain color with a predominance of black and white tones with gas inclusions. These microparticles of space origin are composed of a silicate base.
7. Balls of a dissimilar structure made of glass and metal. Such elements are characterized by microscopic dimensions within 20 nm.

According to the astronomical location, 5 groups of cosmic dust are distinguished:

• Dust in intergalactic space. This kind can distort the dimensions of distances in certain calculations and can change the color of space objects.
• Formations within the Galaxy. The space within these limits is always filled with dust from the destruction of cosmic bodies.
• A substance concentrated between the stars. It is most interesting due to the presence of a shell and a hard core.
• Dust located near a specific planet. It is usually found in the ring system of a celestial body.
• Dust clouds around the stars. They circle in the orbital path of the star itself, reflecting its light and creating a nebula.

Three groups by the total specific gravity of microparticles look like this:

1. Metal band. Representatives of this subspecies have a specific gravity of more than five grams per cubic centimeter, and their base consists mainly of iron.
2. Silicate-based group. The base is transparent glass with a specific gravity of approximately three grams per cubic centimeter.
3. Mixed group. The very name of this association indicates the presence of both glass and iron in the structure of microparticles. The base also includes magnetic elements.

Four groups according to the similarity of the internal structure of cosmic dust microparticles:

• Hollow-filled spherules. This species is often found in places where meteorites fall.
• Spherules of metal formation. This subspecies has a core of cobalt and nickel, as well as a shell that has oxidized.
• Balls of uniform addition. These grains have an oxidized shell.
• Balls with a silicate base. The presence of gas inclusions gives them the appearance of ordinary slags, and sometimes foam.

It should be remembered that these classifications are very arbitrary, but they serve as a certain reference point for designating the types of dust from space.

Composition and characteristics of the components of cosmic dust

Let's take a closer look at what cosmic dust consists of. There is a certain problem in determining the composition of these microparticles. Unlike gaseous substances, solids have a continuous spectrum with relatively few bands that are blurred. As a result, it becomes difficult to identify cosmic dust particles.

The composition of cosmic dust can be considered using the example of the main models of this substance. These include the following subspecies:

1. Ice particles, the structure of which includes a core with a refractory characteristic. The shell of such a model consists of lightweight elements. Large particles contain atoms with elements of magnetic properties.
2. Model MRN, the composition of which is determined by the presence of silicate and graphite inclusions.
3. Oxide cosmic dust, which is based on the diatomic oxides of magnesium, iron, calcium and silicon.

General classification by chemical composition of cosmic dust:

• Balls with a metallic formation nature. Such microparticles contain an element such as nickel.
• Metal balls with iron and nickel free.
• Silicone based circles.
• Irregularly shaped nickel-iron balls.

More specifically, you can consider the composition of cosmic dust on the example found in oceanic silt, sedimentary rocks and glaciers. Their formula will differ little from one another. Findings during the study of the seabed are balls with a silicate and metal base with the presence of chemical elements such as nickel and cobalt. Also in the depths of the water element, microparticles with the presence of aluminum, silicon and magnesium were found.

The soil is fertile for the presence of cosmic material. A particularly large number of spherules were found in places where meteorites fell. They are based on nickel and iron, as well as all kinds of minerals such as troilite, cohenite, steatite and other components.

Glaciers also hide aliens from outer space in their clumps in the form of dust. Silicate, iron and nickel form the basis of the found spherules. All mined particles were classified into 10 clearly delineated groups.

Difficulties in determining the composition of the studied object and differentiating it from impurities of terrestrial origin leave this question open for further research.

Influence of cosmic dust on vital processes

The influence of this substance has not been fully studied by specialists, which gives great opportunities in terms of further activities in this direction. At a certain height, with the help of rockets, a specific belt consisting of cosmic dust was discovered. This gives grounds to assert that such extraterrestrial matter affects some of the processes taking place on planet Earth.

The effect of cosmic dust on the upper atmosphere

Recent studies indicate that the amount of cosmic dust can affect the change in the upper atmosphere. This process is very significant, because it leads to certain fluctuations in the climatic characteristics of the planet Earth.

A huge amount of dust from the collision of asteroids fills the space around our planet. Its amount reaches almost 200 tons per day, which, according to scientists, cannot but leave its consequences.

The most susceptible to this attack, according to the same experts, is the northern hemisphere, whose climate is prone to cold temperatures and dampness.

The impact of space dust on cloud formation and climate change is not yet well understood. New research in this area is raising more and more questions, the answers to which have not yet been received.

Effect of dust from space on the transformation of oceanic silt

Irradiation of cosmic dust by the solar wind leads to the fact that these particles fall on the Earth. Statistics show that the lightest of the three isotopes of helium in huge quantities gets through dust particles from space into oceanic silt.

The absorption of elements from space by minerals of ferromanganese origin served as the basis for the formation of unique ore formations on the ocean floor.

At the moment, the amount of manganese in the regions close to the polar circle is limited. All this is due to the fact that cosmic dust does not enter the oceans in those areas due to ice sheets.

The effect of cosmic dust on the composition of the World Ocean water

If we consider the glaciers of Antarctica, then they are striking in the number of meteorite remnants found in them and the presence of cosmic dust, which is a hundred times higher than the usual background.

An excessively high concentration of the same helium-3, valuable metals in the form of cobalt, platinum and nickel, makes it possible to assert with confidence the fact of the interference of cosmic dust in the composition of the ice sheet. At the same time, the substance of extraterrestrial origin remains in its original form and not diluted by the waters of the ocean, which in itself is a unique phenomenon.

According to some scientists, the amount of cosmic dust in such peculiar ice sheets over the past million years has been on the order of several hundred trillion meteorite formations. During the warming period, these covers melt and carry elements of cosmic dust into the World Ocean.

Watch a video about cosmic dust:

This cosmic neoplasm and its influence on some factors of the life of our planet have been little studied. It is important to remember that a substance can affect climate change, the structure of the ocean floor and the concentration of certain substances in the waters of the oceans. Photos of cosmic dust indicate how many more mysteries these microparticles are concealing in themselves. All this makes learning like this interesting and relevant!

Scientists at the University of Hawaii made a sensational discovery - cosmic dust contains organic matter , including water, which confirms the possibility of transferring various life forms from one galaxy to another. Comets and asteroids plying in space regularly bring masses of stardust into the atmosphere of the planets. Thus, interstellar dust acts as a kind of "transport" that can deliver water with organic matter to the Earth and to other planets of the solar system. Perhaps, once, a stream of cosmic dust led to the origin of life on Earth. It is possible that life on Mars, the existence of which causes much controversy in scientific circles, could arise in the same way.

The mechanism of water formation in the structure of cosmic dust

In the process of moving in space, the surface of interstellar dust particles is irradiated, which leads to the formation of water compounds. This mechanism can be described in more detail as follows: hydrogen ions present in solar vortex flows bombard the shell of cosmic dust grains, knocking out individual atoms from the crystalline structure of a silicate mineral - the main building material of intergalactic objects. As a result of this process, oxygen is released, which reacts with hydrogen. Thus, water molecules are formed containing inclusions of organic substances.

Colliding with the planet's surface, asteroids, meteorites and comets bring a mixture of water and organic matter to its surface.

What cosmic dust- a companion of asteroids, meteorites and comets, carries molecules of organic carbon compounds, it was known before. But the fact that stardust also transports water has not been proven. It is only now that American scientists have discovered for the first time that organic matter carried by particles of interstellar dust together with water molecules.

How did the water get to the moon?

The discovery of scientists from the United States may help lift the veil of mystery over the mechanism of formation of strange ice formations. Despite the fact that the surface of the Moon is completely dehydrated, an OH compound was detected on its shadow side by means of sounding. This find testifies in favor of the possible presence of water in the bowels of the Moon.

The reverse side of the Moon is completely covered with ice. Perhaps it was with cosmic dust that water molecules hit its surface many billions of years ago.

Since the era of the Apollo lunar rovers in lunar exploration, when samples of lunar soil were brought to Earth, scientists have concluded that sunny wind causes changes in the chemical composition of the stardust that covers the surfaces of planets. Debates were still going on about the possibility of the formation of water molecules in the thickness of the space dust on the Moon, but the analytical methods of research available at that time were not able to either prove or refute this hypothesis.

Stardust is the carrier of life forms

Due to the fact that water is formed in a very small volume and is localized in a thin shell on the surface cosmic dust, only now it has become possible to see it with a high-resolution electron microscope. Scientists believe that a similar mechanism for the movement of water with molecules of organic compounds is possible in other galaxies, where it revolves around the "parent" star. In their further research, scientists propose to identify in more detail which inorganic and organic matter carbon-based are present in the structure of stardust.

Interesting to know! An exoplanet is a planet that is outside the solar system and orbits a star. At the moment, about 1000 exoplanets have been visually detected in our galaxy, forming about 800 planetary systems. However, indirect methods of detection indicate the existence of 100 billion exoplanets, of which 5-10 billion have parameters similar to those of the Earth, that is, they are. The Kepler astronomical telescope satellite launched into space in 2009 in cooperation with the Planet hunters program made a significant contribution to the mission of finding planetary groups similar to the solar system.

How could life arise on Earth?

It is very likely that comets traveling in space at high speed are capable of creating enough energy when they collide with a planet, so that the synthesis of more complex organic compounds, including amino acid molecules, begins from the ice components. A similar effect occurs when a meteorite collides with the icy surface of the planet. The shockwave creates heat, which triggers the formation of amino acids from individual molecules of cosmic dust blown by the solar wind.

Interesting to know! Comets are made up of large chunks of ice formed by the condensation of water vapor during the early days of the solar system, about 4.5 billion years ago. In their structure, comets contain carbon dioxide, water, ammonia, methanol. These substances, when comets collide with the Earth, at an early stage of its development, could produce enough energy for the production of amino acids - building proteins necessary for the development of life.

Computer simulations have shown that ice comets that crashed against the Earth's surface billions of years ago may have contained prebiotic mixtures and the simplest amino acids such as glycine, from which life on Earth subsequently originated.

The amount of energy released during the collision of a celestial body and a planet is enough to trigger the formation of amino acids

Scientists have found that ice bodies with identical organic compounds found in comets can be found within the solar system. For example, Enceladus, one of the satellites of Saturn, or Europa, the moon of Jupiter, contain in its shell organic matter mixed with ice. Hypothetically, any bombardment of satellites by meteorites, asteroids or comets can lead to the emergence of life on these planets.

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Space x-ray background

Oscillations and Waves: Characteristics of various oscillatory systems (oscillators).

Tearing the Universe

Dusty near-planetary complexes: fig4

Space dust properties

S. V. Bozhokin Saint Petersburg State Technical University	Content

Introduction

Many people admire with delight the wonderful spectacle of the starry sky, one of the greatest creations of nature. In the clear autumn sky, you can clearly see how a faintly luminous strip, called the Milky Way, which has irregular outlines with different width and brightness. If we look at the Milky Way, which forms our Galaxy, through a telescope, it turns out that this bright stripe breaks up into many faintly luminous stars, which for the naked eye merge into a solid glow. It has now been established that the Milky Way consists not only of stars and star clusters, but also of gas and dust clouds.

Huge interstellar clouds of glowing rarefied gases got the name gaseous diffuse nebulae... One of the most famous is the nebula in constellation orion, which is visible even to the naked eye near the middle of the three stars that form the "sword" of Orion. The gases that form it glow with cold light, re-emitting the light of neighboring hot stars. The composition of gaseous diffuse nebulae consists mainly of hydrogen, oxygen, helium and nitrogen. Such gaseous or diffuse nebulae serve as a cradle for young stars, which are born in the same way as ours was once born. solar system... The process of star formation is continuous, and stars continue to appear today.

V interstellar space Diffuse dust nebulae are also observed. These clouds are made up of tiny hard dust particles. If there is a bright star near the dusty nebula, then its light is scattered by this nebula and the dusty nebula becomes directly observable(fig. 1). Gas and dust nebulae can generally absorb light from the stars behind them, which is why they are often seen in sky images as black gaping dips against the background of the Milky Way. Such nebulae are called dark. There is one very large dark nebula in the sky of the southern hemisphere, which the sailors called the Charcoal Sack. There is no clear boundary between gas and dust nebulae, so they are often observed together as gas and dust nebulae.

Diffuse nebulae are only condensations in that extremely rarefied interstellar matter which was named interstellar gas... Interstellar gas is detected only when observing the spectra of distant stars, causing additional ones in them. Indeed, over a long distance, even such a rarefied gas can absorb the radiation of stars. Emergence and rapid development radio astronomy made it possible to detect this invisible gas by the radio waves that it emits. The huge dark clouds of interstellar gas are composed primarily of hydrogen, which even with low temperatures emits radio waves at a length of 21 cm. These radio waves pass unhindered through gas and dust. It was radio astronomy that helped us study the shape of the Milky Way. Today we know that gas and dust, mixed with large clusters of stars, form a spiral, the branches of which, emerging from the center of the galaxy, twine around its middle, creating something like a long-tentacled cuttlefish caught in a whirlpool.

Currently, a huge amount of matter in our Galaxy is in the form of gas and dust nebulae. Interstellar diffuse matter is concentrated in a relatively thin layer in equatorial plane our star system. Clouds of interstellar gas and dust block the center of the galaxy from us. Clouds of cosmic dust leave tens of thousands of open star clusters invisible to us. Fine cosmic dust not only weakens the light of the stars, but also distorts them spectral composition... The fact is that when light radiation passes through cosmic dust, then it is not only attenuated, but also changes color. The absorption of light by cosmic dust depends on the wavelength, so of all optical spectrum of the star blue rays are absorbed more strongly and photons corresponding to red color are absorbed weaker. This effect leads to the phenomenon of reddening of the light of stars passing through the interstellar medium.

For astrophysicists great value has the study of the properties of cosmic dust and the clarification of the effect that this dust has in the study physical characteristics of astrophysical objects... Interstellar absorption and interstellar polarization of light, infrared radiation of regions of neutral hydrogen, deficiency chemical elements in the interstellar medium, the formation of molecules and the birth of stars - in all these problems a huge role belongs to cosmic dust, the properties of which are considered in this article.

The origin of cosmic dust

Cosmic dust particles arise mainly in the slowly flowing atmospheres of stars - red dwarfs, as well as during explosive processes on stars and violent ejection of gas from galactic nuclei. Other sources of cosmic dust formation are planetary and protostellar nebulae , stellar atmospheres and interstellar clouds. In all processes of the formation of cosmic dust particles, the gas temperature drops when the gas moves outward and at some point passes through the dew point, at which vapor condensation forming the cores of the dust particles. The centers for the formation of a new phase are usually clusters. Clusters are small groups of atoms or molecules that form a stable quasi-molecule. In collisions with an already formed nucleus of a dust grain, atoms and molecules can attach to it, or chemical reactions with dust atoms (chemisorption), or completing the forming cluster. In the densest parts of the interstellar medium, the concentration of particles in which is cm -3, the growth of a dust grain can be associated with coagulation processes, in which dust grains can stick to each other without being destroyed. Coagulation processes, depending on the properties of the surface of the dust grains and their temperatures, occur only when collisions between dust grains occur at low relative velocities of collisions.

In fig. Figure 2 shows the growth of cosmic dust clusters by adding monomers. The resulting amorphous cosmic dust grain can be a cluster of atoms with fractal properties. Fractals are called geometric objects: lines, surfaces, spatial bodies with a highly irregular shape and possessing the property of self-similarity. Self-similarity means the invariability of the basic geometric characteristics fractal object when you change the scale. For example, images of many fractal objects appear very similar when the resolution is increased in a microscope. Fractal clusters are highly branched porous structures formed under highly nonequilibrium conditions when solid particles of similar sizes are combined into one whole. Under terrestrial conditions, fractal aggregates are obtained at vapor relaxation metals in non-equilibrium conditions, with the formation of gels in solutions, with coagulation of particles in fumes. The model of a fractal cosmic dust grain is shown in Fig. 3. Note that the processes of coagulation of dust grains occurring in protostellar clouds and gas and dust disks, increase significantly at turbulent motion interstellar matter.

The cores of cosmic dust, consisting of refractory elements, a few hundredths of a micron in size are formed in the shells of cool stars during a smooth outflow of gas or during explosive processes. Such cores of dust grains are resistant to many external influences.

By mass, solid dust particles make up an insignificant part of the Universe, but it is thanks to interstellar dust that stars, planets and people who study space and simply admire the stars have arisen and continue to appear. What kind of substance is this - cosmic dust? What compels people to equip expeditions into space worth the annual budget of a small state in the hope of only, and not in the firm confidence, to extract and bring to Earth even a tiny handful of interstellar dust?

Between the stars and planets

Dust in astronomy is called small, fractions of a micron, solid particles flying in outer space. Cosmic dust is often conventionally divided into interplanetary and interstellar dust, although, obviously, interstellar entry into interplanetary space is not prohibited. It is not easy to find it there, among the "local" dust, the probability is low, and its properties near the Sun can change significantly. Now, if you fly farther, to the borders of the solar system, there the probability of catching real interstellar dust is very high. The ideal option is to go beyond the solar system altogether.

The dust is interplanetary, at least in comparative proximity to the Earth - the matter is quite studied. Filling the entire space of the solar system and concentrated in the plane of its equator, it was born in large part as a result of accidental collisions of asteroids and the destruction of comets that approached the Sun. The composition of the dust, in fact, does not differ from the composition of meteorites falling to the Earth: it is very interesting to study it, and there are still a lot of discoveries in this area, but there seems to be no special intrigue here. But thanks to this particular dust, in good weather in the west immediately after sunset or in the east before sunrise, you can admire the pale cone of light above the horizon. This is the so-called zodiacal - sunlight scattered by small cosmic dust particles.

Much more interesting is interstellar dust. Its distinctive feature is the presence of a solid core and shell. The core appears to be composed primarily of carbon, silicon, and metals. And the shell is predominantly of gaseous elements frozen on the surface of the core, crystallized in the conditions of "deep freezing" of interstellar space, and this is about 10 kelvin, hydrogen and oxygen. However, there are also more complex admixtures of molecules in it. These are ammonia, methane and even polyatomic organic molecules that stick to a speck of dust or are formed on its surface during wanderings. Some of these substances, of course, fly away from its surface, for example, under the influence of ultraviolet radiation, but this process is reversible - some fly away, others freeze or are synthesized.

Now, in the space between the stars or near them, they have already been found, of course, not by chemical, but by physical, that is, spectroscopic, methods: water, oxides of carbon, nitrogen, sulfur and silicon, hydrogen chloride, ammonia, acetylene, organic acids such as formic and acetic, ethyl and methyl alcohols, benzene, naphthalene. They even found an amino acid - glycine!

It would be interesting to catch and study the interstellar dust that penetrates into the solar system and probably falls to the Earth. The problem of "catching" it is not easy, because only a few interstellar dust particles manage to preserve their ice "coat" in the sun's rays, especially in the Earth's atmosphere. Large ones get too hot - their space velocity cannot be quickly extinguished, and dust particles "burn". Small ones, however, plan in the atmosphere for years, preserving part of the shell, but then the problem arises of finding them and identifying them.

There is one more, very intriguing detail. It concerns the dust, the nuclei of which are composed of carbon. Carbon synthesized in the cores of stars and escaping into space, for example, from the atmosphere of aging (such as red giants) stars, flying out into interstellar space, cools and condenses - in much the same way as after a hot day, fog from cooled water vapor gathers in the lowlands. Depending on the crystallization conditions, layered graphite structures, diamond crystals (just imagine - whole clouds of tiny diamonds!) And even hollow balls of carbon atoms (fullerenes) can be obtained. And in them, perhaps, like in a safe or a container, particles of the atmosphere of a very ancient star are stored. Finding such specks of dust would be a huge success.

Where is cosmic dust found?

I must say that the very concept of the cosmic vacuum as something completely empty has long remained only poetic metaphor... In fact, the entire space of the Universe, both between stars and between galaxies, is filled with matter, flows of elementary particles, radiation and fields - magnetic, electric and gravitational. Everything that can, relatively speaking, be touched is gas, dust and plasma, the contribution of which to the total mass of the Universe, according to various estimates, is only about 1-2% with an average density of about 10-24 g / cm 3. There is the largest amount of gas in space, almost 99%. These are mainly hydrogen (up to 77.4%) and helium (21%), the rest account for less than two percent of the mass. And then there is dust - its mass is almost a hundred times less than gas.

Although sometimes the void in interstellar and intergalactic spaces is almost ideal: sometimes there is 1 liter of space for one atom of matter! There is no such vacuum either in terrestrial laboratories or within the solar system. For comparison, an example can be given: in 1 cm 3 of the air we breathe, there are approximately 30,000,000,000,000,000,000 molecules.

This matter is distributed very unevenly in interstellar space. Most of the interstellar gas and dust forms a layer of gas and dust near the plane of symmetry of the Galaxy disk. Its thickness in our Galaxy is several hundred light years. Most of the gas and dust in its spiral branches (arms) and core are concentrated mainly in giant molecular clouds ranging in size from 5 to 50 parsecs (16-160 light years) and weighing tens of thousands and even millions of solar masses. But even inside these clouds, matter is also distributed inhomogeneously. In the main volume of the cloud, the so-called fur coat, mainly of molecular hydrogen, the density of particles is about 100 pieces per 1 cm 3. In the seals inside the cloud, it reaches tens of thousands of particles in 1 cm 3, and in the cores of these seals - in general, millions of particles in 1 cm 3. It is this unevenness in the distribution of matter in the Universe that is due to the existence of a star, a planet and, ultimately, ourselves. Because it is in molecular clouds, dense and relatively cold, that stars are born.

Interestingly, the higher the density of the cloud, the more varied it is in composition. At the same time, there is a correspondence between the density and temperature of the cloud (or its individual parts) and those substances whose molecules are found there. On the one hand, it is convenient for studying clouds: by observing their individual components in different spectral ranges from characteristic lines of the spectrum, for example, CO, OH or NH 3, one can "look" into one or another part of it. On the other hand, data on the composition of the cloud allows you to learn a lot about the processes taking place in it.

In addition, in interstellar space, judging by the spectra, there are also such substances, the existence of which in terrestrial conditions is simply impossible. These are ions and radicals. Their reactivity is so high that they react immediately on Earth. And in the rarefied cold space of space, they live long and completely free.

In general, gas in interstellar space is not only atomic. Where it is colder, no more than 50 kelvin, the atoms manage to stick together to form molecules. However, a large mass of interstellar gas is still in an atomic state. This is mainly hydrogen, its neutral form was discovered relatively recently - in 1951. As you know, it emits radio waves 21 cm long (frequency 1 420 MHz), the intensity of which was used to determine how much of it is in the Galaxy. By the way, it is distributed inhomogeneously in the space between the stars. In clouds of atomic hydrogen, its concentration reaches several atoms in 1 cm 3, but between clouds it is orders of magnitude lower.

Finally, gas exists in the form of ions near hot stars. The powerful ultraviolet radiation heats up and ionizes the gas, and it starts to glow. That is why areas with a high concentration of hot gas, with a temperature of about 10,000 K, look like glowing clouds. They are called light gaseous nebulae.

And in any nebula, more or less, there is interstellar dust. Despite the fact that nebulae are conventionally divided into dust and gas, there is dust in both. And in any case, it is the dust that apparently helps the stars to form in the bowels of nebulae.

Foggy objects

Among all space objects, nebulae are perhaps the most beautiful. True, dark nebulae in the visible range look just like black blots in the sky - they are best observed against the background of the Milky Way. But in other ranges of electromagnetic waves, for example, infrared, they are seen very well - and the pictures are very unusual.

Nebulae are called accumulations of gas and dust isolated in space, connected by gravitational forces or external pressure. Their mass can be from 0.1 to 10,000 solar masses, and the size - from 1 to 10 parsecs.

At first, astronomers were annoyed by the nebulae. Until the middle of the 19th century, the discovered nebulae were considered an annoying obstacle that prevented the observation of stars and the search for new comets. In 1714, the Englishman Edmond Halley, whose name the famous comet bears, even made a "black list" of six nebulae so that they would not mislead the "comet catchers", and the Frenchman Charles Messier expanded this list to 103 objects. Fortunately, Sir William Herschel, a musician in love with astronomy, and his sister and son became interested in nebulae. Observing the sky with the help of telescopes built with their own hands, they left behind a catalog of nebulae and star clusters, numbering information about 5,079 space objects!

Herschels practically exhausted the possibilities of optical telescopes of those years. However, the invention of photography and the long exposure time made it possible to find very weakly luminous objects. A little later, spectral methods of analysis, observations in various ranges of electromagnetic waves made it possible in the future not only to detect many new nebulae, but also to determine their structure and properties.

The interstellar nebula looks bright in two cases: either it is so hot that its gas itself glows, such nebulae are called emission; or the nebula itself is cold, but its dust scatters the light of a nearby bright star - this is a reflection nebula.

Dark nebulae are also interstellar clusters of gas and dust. But unlike light gaseous nebulae, sometimes visible even with strong binoculars or a telescope, such as the Orion nebula, dark nebulae do not emit light, but absorb it. When light from a star passes through such nebulae, dust can completely absorb it, converting it into infrared radiation invisible to the eye. Therefore, such nebulae look like starless sinkholes in the sky. V. Herschel called them "holes in the sky." Perhaps the most spectacular of these is the Horsehead Nebula.

However, the dust particles may not completely absorb the light of the stars, but only partially scatter it, while selectively. The fact is that the size of particles of interstellar dust is close to the wavelength of blue light, so it is more scattered and absorbed, and the "red" part of the stars' light reaches us better. By the way, this good way estimate the size of dust particles by how they attenuate light of different wavelengths.

Star from the cloud

The reasons for the appearance of stars are not precisely established - there are only models that more or less reliably explain the experimental data. In addition, the pathways of formation, properties and further fate of stars are very diverse and depend on many factors. However, there is an established concept, or rather, the most elaborated hypothesis, the essence of which, in its most general terms, is that stars are formed from interstellar gas in regions with increased density of matter, that is, in the depths of interstellar clouds. Dust as a material could be ignored, but its role in the formation of stars is enormous.

This happens (in the most primitive version, for a single star), apparently, like this. First, a protostellar cloud condenses from the interstellar medium, which may be due to gravitational instability, but the reasons may be different and are not yet fully understood. One way or another, it contracts and attracts matter from the surrounding space. The temperature and pressure in its center rise until the molecules in the center of this contracting ball of gas begin to disintegrate into atoms and then into ions. This process cools the gas, and the pressure inside the core drops sharply. The core is compressed, and a shock wave propagates inside the cloud, throwing off its outer layers. A protostar is formed, which continues to contract under the action of gravitational forces until, in its center, thermonuclear fusion reactions begin - the conversion of hydrogen into helium. The compression continues for some time, until the forces of gravitational compression are balanced by the forces of gas and radiant pressure.

It is clear that the mass of the formed star is always less than the mass of the nebula that "gave birth" to it. Part of the substance that did not have time to fall on the nucleus, during this process, is "swept away" by the shock wave, radiation and particle flux simply into the surrounding space.

The process of formation of stars and stellar systems is influenced by many factors, including the magnetic field, which often contributes to the "rupture" of a protostellar cloud into two, less often three fragments, each of which is compressed by gravity into its own protostar. This is how, for example, many binary star systems arise - two stars that revolve around a common center of mass and move in space as a whole.

As the stars “age”, nuclear fuel gradually burns out, and the faster, the larger the star. In this case, the hydrogen cycle of reactions is replaced by helium, then as a result of nuclear fusion reactions, increasingly heavy chemical elements are formed, up to iron. In the end, the nucleus, which does not receive more energy from thermonuclear reactions, sharply decreases in size, loses its stability, and its substance, as it were, falls on itself. A powerful explosion occurs, during which matter can heat up to billions of degrees, and interactions between nuclei lead to the formation of new chemical elements, up to the heaviest ones. The explosion is accompanied by a sharp release of energy and the release of matter. A star explodes - this process is called a supernova explosion. Ultimately, the star, depending on its mass, will turn into a neutron star or a black hole.

Probably, this is how it actually happens. In any case, there is no doubt that young, that is, hot, stars and their clusters are mostly located in nebulae, that is, in regions with an increased density of gas and dust. This is clearly seen in photographs taken by telescopes in different wavelength ranges.

Of course, this is nothing more than the roughest exposition of the sequence of events. For us, two points are fundamentally important. First, what is the role of dust in star formation? And the second - where, in fact, does it come from?

Universal refrigerant

In the total mass of cosmic matter, dust itself, that is, atoms of carbon, silicon and some other elements combined into solid particles, is so small that they, in any case, as a building material for stars, it would seem, can not be taken into account. However, in fact, their role is great - it is they who cool the hot interstellar gas, turning it into that very cold dense cloud, from which stars are then obtained.

The fact is that the interstellar gas itself cannot cool down. The electronic structure of the hydrogen atom is such that excess energy, if any, can be given off by emitting light in the visible and ultraviolet regions of the spectrum, but not in the infrared region. Figuratively speaking, hydrogen does not know how to radiate heat. To cool down properly, he needs a "refrigerator", the role of which is played by particles of interstellar dust.

During a collision with dust particles at high speed - unlike heavier and slower dust particles, gas molecules fly quickly - they lose speed and their kinetic energy is transferred to the dust particle. It also heats up and gives off this excess heat to the surrounding space, including in the form of infrared radiation, while it cools down at the same time. So, taking on the heat of interstellar molecules, dust acts as a kind of radiator, cooling a cloud of gas. There is not much of it in terms of mass - about 1% of the mass of the entire substance of the cloud, but this is enough to remove excess heat over millions of years.

When the temperature of the cloud drops, so does the pressure, the cloud condenses and stars can already be born from it. The remnants of the material from which the star was born are, in turn, the source for the formation of planets. Here, dust grains are already included in their composition, and in more... Because, having been born, the star heats up and accelerates all the gas around it, and the dust remains flying nearby. After all, it is capable of cooling and is attracted to a new star much stronger than individual gas molecules. In the end, a dust cloud appears next to the newborn star, and dust-laden gas at the periphery.

Gas planets such as Saturn, Uranus and Neptune are born there. Well, solid planets appear near the star. We have it Mars, Earth, Venus and Mercury. It turns out a fairly clear division into two zones: gas planets and solid ones. So the Earth is largely made from interstellar dust particles. Metallic dust particles became part of the planet's core, and now the Earth has a huge iron core.

The mystery of the young universe

If a galaxy has formed, then where does the dust come from - in principle, scientists understand. Its most significant sources are novae and supernovae, which lose part of their mass, "throwing" the shell into the surrounding space. In addition, dust is born in the expanding atmosphere of the red giants, from where it is literally swept away by the pressure of radiation. In their cool, by the standards of stars, atmosphere (about 2.5 - 3 thousand Kelvin) there are quite a lot of relatively complex molecules.

But here is a riddle that has not yet been solved. It has always been believed that dust is a product of the evolution of stars. In other words, stars should be born, exist for some time, grow old and, say, produce dust in the last supernova explosion. But what came first - an egg or a chicken? The first dust necessary for the birth of a star, or the first star, which for some reason was born without the help of dust, aged, exploded, forming the very first dust.

What happened in the beginning? After all, when the Big Bang happened 14 billion years ago, there were only hydrogen and helium in the Universe, no other elements! It was then from them that the first galaxies began to emerge, huge clouds, and in them - the first stars that had to go through a long life path... Thermonuclear reactions in the cores of stars were supposed to "weld" more complex chemical elements, to convert hydrogen and helium into carbon, nitrogen, oxygen, and so on, and after that the star should have thrown all this into space, exploding or gradually shedding its envelope. Then this mass had to cool, cool down and, finally, turn into dust. But already 2 billion years after the Big Bang, in the earliest galaxies, there was dust! With the help of telescopes, it was discovered in galaxies that are 12 billion light years distant from ours. At the same time, 2 billion years is too short a period for the full life cycle of a star: during this time, most stars do not have time to grow old. Where did the dust come from in the young Galaxy, if there should be nothing but hydrogen and helium, is a mystery.

A speck of dust - a reactor

Not only does interstellar dust act as a kind of universal coolant, perhaps it is thanks to dust that complex molecules appear in space.

The fact is that the surface of a grain of dust can simultaneously serve as a reactor, in which molecules are formed from atoms, and as a catalyst for the reactions of their synthesis. After all, the probability that many atoms of different elements will collide at one point at once, and even interact with each other at a temperature slightly above absolute zero, is unimaginably small. On the other hand, the probability that a grain of dust will consistently collide in flight with various atoms or molecules, especially inside a cold dense cloud, is quite high. Actually, this is what happens - this is how a shell of interstellar dust grains is formed from the atoms and molecules that have been frozen on it.

Atoms are side by side on a solid surface. Migrating over the surface of a grain of dust in search of the most energetically favorable position, the atoms meet and, being in close proximity, are able to react with each other. Of course, very slowly - in accordance with the temperature of the dust particle. The surface of particles, especially those containing metal in the core, can exhibit catalyst properties. Chemists on Earth are well aware that the most effective catalysts are just particles of a fraction of a micron, on which molecules collect and then enter into reactions, which in normal conditions are completely "indifferent" to each other. Apparently, this is how molecular hydrogen is formed: its atoms "stick" to a speck of dust, and then fly away from it - but already in pairs, in the form of molecules.

It may well be that small interstellar dust grains, retaining in their shells a few organic molecules, including the simplest amino acids, and brought to the Earth the first "seeds of life" about 4 billion years ago. This, of course, is nothing more than a beautiful hypothesis. But in her favor is the fact that an amino acid, glycine, is found in the composition of cold gas and dust clouds. Maybe there are others, just so far the capabilities of telescopes do not allow them to be detected.

Dust hunt

It is possible, of course, to study the properties of interstellar dust at a distance - with the help of telescopes and other instruments located on Earth or on its satellites. But it is much more tempting to catch interstellar dust particles, and then study in detail, find out - not theoretically, but practically, what they consist of, how they are arranged. There are two options. You can get to the depths of space, collect interstellar dust there, bring it to Earth and analyze it by everyone possible ways... Or you can try to fly out of the solar system and on the way analyze the dust right on board the spacecraft, sending the received data to Earth.

The first attempt to bring samples of interstellar dust, and in general the matter of the interstellar medium, was made by NASA several years ago. The spacecraft was equipped with special traps - collectors for collecting interstellar dust and particles of the cosmic wind. To catch the dust particles without losing their shell, the traps were filled with a special substance - the so-called airgel. This very light foamy substance (the composition of which is a trade secret) resembles jelly. Once in it, the dust particles get stuck, and then, like in any trap, the lid slams shut to be open already on Earth.

This project was called Stardust - Stardust. His program is grandiose. After launch in February 1999, the equipment on board should eventually collect samples of interstellar dust and, separately, dust in the immediate vicinity of Comet Wild-2, which flew near Earth in February last year. Now, with containers filled with this precious cargo, the ship is flying home to land on January 15, 2006 in Utah, near Salt Lake City (USA). It is then that astronomers will finally see with their own eyes (with the help of a microscope, of course) those very dust particles, the models of the composition and structure of which they have already predicted.

And in August 2001, Genesis flew for samples of matter from deep space. This NASA project was aimed primarily at capturing solar wind particles. After spending 1,127 days in outer space, during which it flew about 32 million km, the spacecraft returned and dropped a capsule with the obtained samples - traps with ions, particles of the solar wind - onto the Earth. Alas, a misfortune happened - the parachute did not open, and the capsule hit the ground with a full swing. And it crashed. Of course, the wreckage was collected and carefully examined. However, in March 2005, at a conference in Houston, program participant Don Barnetti said that four collectors with solar wind particles were not affected, and scientists are actively studying their contents, 0.4 mg of the captured solar wind, in Houston.

However, now NASA is preparing a third project, even more ambitious. This will be the Interstellar Probe space mission. This time the spacecraft will move away at a distance of 200 AU. e. from the Earth (a. e. - the distance from the Earth to the Sun). This ship will never return, but it will all be "stuffed" with a wide variety of equipment, including for the analysis of samples of interstellar dust. If everything works out, interstellar dust particles from deep space will finally be captured, photographed and analyzed - automatically, right on board the spacecraft.

Formation of young stars

1. A giant galactic molecular cloud with a size of 100 parsecs, a mass of 100,000 suns, a temperature of 50 K, and a density of 10 2 particles / cm 3. Inside this cloud there are large-scale condensations - diffuse gas and dust nebulae (1-10 pc, 10,000 suns, 20 K, 103 particles / cm 3) and small condensations - gas and dust nebulae (up to 1pc, 100-1,000 suns, 20 K, 10 4 particles / cm 3). Inside the latter, there are just clots of globules with a size of 0.1 pc, a mass of 1-10 suns and a density of 10-10 6 particles / cm 3, where new stars are formed

2. The birth of a star inside a gas and dust cloud

3. New star with its radiation and stellar wind accelerates the surrounding gas from itself

4. A young star enters space, clean and free of gas and dust, pushing aside the nebula that gave rise to it

Stages of "embryonic" development of a star equal in mass to the Sun

5. The origin of a gravitationally unstable cloud with a size of 2,000,000 suns, with a temperature of about 15 K and an initial density of 10 -19 g / cm 3

6. A few hundred thousand years later, this cloud forms a core with a temperature of about 200 K and a size of 100 suns, its mass is still only 0.05 of the solar

7. At this stage, the core with a temperature of up to 2,000 K shrinks sharply due to hydrogen ionization and simultaneously heats up to 20,000 K, the velocity of matter falling onto a growing star reaches 100 km / s

8. A protostar the size of two suns with a center temperature of 2x10 5 K and a surface temperature of 3x10 3 K

9. The last stage in the pre-evolution of a star is slow compression, during which the isotopes of lithium and beryllium are burned out. Only after the temperature rises to 6x10 6 K in the interior of the star, thermonuclear reactions of the synthesis of helium from hydrogen are launched. The total duration of the nucleation cycle of a star like our Sun is 50 million years, after which such a star can safely burn for billions of years

Olga Maksimenko, candidate of chemical sciences