Jean LaPaz

“ When and where will the next crater-producing fall occur? Perhaps on the earth, perhaps on the moon, for our nearest neighbor in space has also been the target of meteorites of huge size. The effects of this meteoritic bombardment are shown by the rarest and most striking type of lunar crater: that which exhibits long, bright rays extending outward from the crater itself as the spokes of a wheel radiate from its hub. These so-called ray-craters show to best advantage at or near the time of full moon, when they become one of the most remarkable features visible on our satellite. ”

“ Because the particles that make a meteor shower are moving through space along parallel paths as they come into the earth’s atmosphere, the meteors all seem to shoot out from a single small area in the sky. ”

“ In earlier days, most scientists believed that the craters on the moon had all been formed by volcanic action. Now the pendulum of scientific opinion seems to have swung toward the view that all the thousands of lunar craters are the result of meteorite impacts that took place in the long distant past. Both views are better examples of how scientific “fashions” control men’s minds than they are of explanations that really account for all of the observed facts—as any acceptable explanation must do. ”

“ Each type of radiant energy incident upon our earth—whether that energy be light from the sun or from the more distant stars or the galaxies, or the reflected light from the planets and moons of our Solar System, or the less familiar forms of radiation, such as radio waves and cosmic rays—must be measured and permanently recorded by complicated instruments. Often the results given by even the most sensitive and tractable of these scientific robots turn out to be exceedingly difficult for man, their master, to interpret. ”

“ So dense is the forest that in summer, a man can see no more than 10 or 12 feet in any direction. Yet in winter, the explorer’s lot is no easier; for, although the deciduous trees then stand leafless, the ground is covered by three feet or more of snow. And in the early fall, violent cloudbursts often flood the taiga, making travel impossible.
Such was the inhospitable region in which the Ussuri, or (as 14 it is now known in the U.S.S.R.) Sikhote-Alin meteorite, had chanced to fall. ”

“ Scientists in Germany, England, France, and Russia engaged in the painstaking mineralogical study and classification of individual meteorite specimens.
The modern science of meteoritics is rooted deep in the nineteenth century. Many special fields of investigation had their beginnings then. Scientists became interested in the chemistry, the mineralogy, and the metallurgy of meteorites; in the orbits of meteorites and the trajectories they follow through the earth’s atmosphere down to impact with the ground; and in the distribution of meteorite falls in space and time. ”

“ People find a great many meteorites that were not seen to fall. Most of these landed on the surface of the earth at some time in the remote past or happened to fall in an originally unpopulated portion of the land area of the globe. Generally, such meteorites are discovered entirely by accident, although in recent years quite a few recoveries of unwitnessed falls have been made by design. This has been the case during the systematic surveys with meteorite detectors conducted around such recognized meteorite crater areas as Canyon Diablo, Arizona; Odessa, Texas; and Wolf Creek, Australia. ”

“ The most important point on a fireball path is the point of disappearance. The most valuable single piece of information you can supply about a meteorite fall is as accurate an answer as possible to the question: In what compass direction were you looking when you last saw the fireball? ”

“ Reading of the possibility of sending out expeditions to find large iron meteorites in the depths of space may bring to your mind an image of the fearless mariners of old who sailed their stout ships over dangerous, often uncharted seas in search of the great whales. ”

“ First of all, meteorites neither all look alike nor have the same composition. The general term “meteorite” applies to any mass that reaches the earth from space. Such masses are made up of metals and minerals in varying proportions. The term “meteorite” is nearly as general in meaning as the word “rock,” which geologists apply to bodies, large and small, that are formed by earth processes and are composed of various kinds of minerals. Actually, there are almost as many different kinds of meteorites as there are kinds of rocks ”

“ We have a specialized word, meteoritics, for the study of meteors and meteorites. No one should confuse meteoritics with meteorology, which is the science of things other than meteors and meteorites, in the atmosphere—for example, clouds, storms, air currents. ”

“ Meteorites do not merely fall upon the earth (as most astronomical textbooks still insist) , but usually penetrate into it—often quite deeply. In fact, one of our mathematical investigations showed that perhaps 100,000 times as much meteoritic nickel-iron is concentrated below maximum plow-depth (approximately one foot) as lies above that depth. Clearly, some form of instrument capable of detecting deeply buried meteorites needed to be devised if this wealth of buried material was not to be lost to science. This need was answered by the development of special meteorite detectors. ”

“ Studies have shown that the people of the earth have a great deal more to do with “concentrations” of meteorite recoveries than anything else. Population density is the first important factor. Clearly, the more people living in a given area, the higher the probability that a meteorite fall will be seen and reported and that the fallen mass itself will be recovered. A prime example is India, one of the most densely populated regions of the world. Of the 102 meteorites recovered in that country up to 1953, 97 were of witnessed fall. ”

“ The first thing to be said on this subject is, of course, that not all holes in the ground, however large and impressive, were necessarily formed by the impact of meteorites. Features that resemble meteorite craters may result from certain ordinary earth-processes. For example, the rock layers underlying a particular area may be dissolved away by waters circulating beneath the surface of the ground. The overlying crust will eventually collapse into the empty space, and what geologists call a “sink hole” or a “sink” is formed. ”

“ The direction from which they do approach strongly influences the speed of these bodies as they plunge through the earth’s atmosphere. A meteorite moving slowly about the sun in the same direction as the earth and chancing to catch up with our globe more or less from behind will have an observed speed of only a few miles a second. For example, the speed calculated from Harvard meteor-photographs of one such not-too-spectacular “rear-end” collision amounted to no more than 7.3 miles per second, just about the speed a rocket must acquire to escape from the apron strings of Mother Earth. ”

“ But as the need for iron and nickel increases on a metal-hungry earth, vast engineering projects may well be undertaken to “snare” the larger metal meteorites and equip them with rocket motors. This will be done so that by use of rocket power, the natural orbits of the meteorites can be changed into orbits bringing them back to earth. Unlike the natural, uncontrolled Canyon Diablo meteorite fall that vaporized what would have been a rich nickel-iron deposit, the rocket-controlled meteoritic “metal mines” will be eased down to earth all in one piece. ”

“ In the relatively near future, men will certainly land on the surface of the moon. We know from radiometric studies that some degree of radioactivity is induced in meteorites by the full-intensity cosmic radiation to which they have been exposed during their motion through space. The nearly airless moon, like the meteorites, has also been exposed to very intense cosmic radiation for a long time. So those who are planning to land on our satellite are concerned about the radioactivities they will encounter when they begin their explorations of the lunar surface. ”

“ This fact is mentioned to show that important scientific evidence is sometimes unwittingly destroyed before investigators can get a chance to examine it.
Along with the rapid increase in the number of man-made buildings has, of course, gone a simultaneous increase in the world’s population itself. A person does not present as large a target to a falling meteorite as a house or barn, but even so, if there were enough people on the earth, it would seem that someone was bound to be hit sooner or later. ”

“ When confronted with the “fallen” masses themselves, the authorities often refused to examine them, or if they did, insisted that these masses were only rocks that had been struck by lightning. Such were the opinions of learned men around the close of the eighteenth century.
Fortunately, scientific facts have a stubborn way of winning out in the long run. A major part of the credit for seeing that the truth regarding meteorite falls was at last recognized must go to E. F. F. Chladni, a German physicist, and to Edward Howard, an English chemist. ”

“ If the Podkamennaya Tunguska meteorite was contraterrene, then the soil in the impact area must have been made radioactive in the same way that the earth around the “ground zero” of a nuclear explosion is contaminated by radioactivity. After the senior author had repeatedly urged Russian scientists (who are the only ones that have been permitted to visit the site of the Podkamennaya Tunguska fall) to try to detect any long-lasting radioactivities that might still be present in the ground at Podkamennaya Tunguska, such a radioactivity survey was finally carried out in the summer of 1960. ”

“ Belated study established, however, both the truthfulness of the Tunguse reports and the exceedingly unusual character of the meteorite fall itself. In spite of the overwhelming and, in fact, worldwide evidence that the Podkamennaya Tunguska fall was one of the greatest and most violent in history, no meteorites have ever been recovered from any part of the region devastated by its impact. It is the one and only true meteorite crater that is meteoriteless! ”

“ The majority of the meteors we observe represent the heat-induced “evaporation” of exceedingly small fragments of cosmic matter. The smallest meteor-forming bodies reach the surface of the earth only as the finest of dust particles or as microscopic droplets of solidified meteorite melt.
These residues descend slowly through the atmosphere and may be carried for great distances. Afterwards, they may be found scattered so widely and uniformly on the ground that their presence in any given locality cannot be accounted for by the fall of any specific meteorite. ”

“ We hope our book will instill in the reader an abiding interest in the location and protection, the recovery and preservation and especially in the study of those cosmic missiles of iron, iron-stone, or stony composition that represent mankind’s only ponderable links with the vast universe lying beyond the limits of the earth’s atmosphere. ”

“ From the whole vast area of Siberia, on the other hand, only 20 meteorite falls and 23 finds have been reported during the same interval.
In the past, scientists have suggested that various natural forces, such as the magnetic field of the earth or the attraction of high and massive mountain ranges, might cause more meteorites to fall in one place than another. But all available evidence indicates that this is not the case. The fall of meteorites upon the earth has been and is a process that shows no apparent pattern. ”

“ Such a large iron mass alters or distorts the local magnetic field of the earth on which the direction-finding ability of the ordinary compass depends. It is this very characteristic, so bothersome to the user of a compass, that is the principle on which meteorite detectors work. For if an electrically driven meteorite detector capable of generating its own magnetic field is carried over a deeply buried iron meteorite, the instrument’s magnetic field will be distorted by the presence of the metal mass, just as the local magnetic field of the earth was distorted by the metal of the automobile. ”

“ The need for such metals can only become more and more acute.
According to one of the currently favored explanations of the origin of the meteorites, the core-fragments of the parent meteorite-planet are solid masses of nickel-iron alloy—like the mass that blasted out the Canyon Diablo meteorite crater. If this meteorite-planet hypothesis finally wins general acceptance, the meteoriticist of the future is almost sure to be set the task of pin-pointing as exactly as possible the whereabouts in space and time of the most easily accessible cosmic nickel-iron lodes of this sort. ”

“ So they reject the theory that such dust found in the Podkamennaya Tunguska area is specifically connected with the meteorite that fell there a half century ago.
If sizable chunks of meteoritic material enter the atmosphere, they may produce exceptionally large and brilliant meteors. A spectacular meteor is generally known as a “fireball” if it is as bright as Venus or Jupiter. It receives the French term bolide if, in addition to showing great brilliance, its flight is accompanied by detonations like the alarming sounds heard at the time of the Ussuri and Norton meteorite falls. ”

“ Hailstones have a good deal more striking power, as may have been painfully demonstrated on your own head. And, finally, such masses as falling meteorites (and especially those orbiting in space, unretarded by atmospheric resistance) have an extraordinarily formidable ballistic potential. This is because meteorites are not only tough and dense, as good projectiles must be, but are also moving at high velocities—particularly high if the meteorites come into the Solar System from interstellar space. ”

“ In the field of cosmic ray studies, particularly those concerned with the protection of space travelers from harmful radiation, meteoritics can be of help. The recovered meteorites have already come through those regions that would be crossed by even the farthest-ranging spaceships. Consequently, a great deal can be learned from the study of meteorites about the intensity of the cosmic radiation that the crews of such ships must face once they get outside the earth’s protective air-shield. ”

“ The iron and stony-iron meteorites are very heavy. A 1-inch cube of iron meteorite weighs approximately 8 times as much as a 1-inch cube of ice. Even the stones, which are only about half as dense as the irons, are much heavier than ordinary rocks.
Does your specimen show a thin blackish or brownish crust on its outer surfaces? You will recall that specimens of both the Ussuri and Norton meteorites showed a “glaze” of fused material which we call fusion crust. Most freshly-fallen meteorites are covered with such a crust. ”

“ In fact, at the present time, several asteroids move well within the orbits of the earth and Venus. It is quite possible therefore that such a large meteorite crater as the one at Canyon Diablo, was produced by the prehistoric fall of one of these small members of our Solar System. If so, we have reason to believe that a core-fragment of the meteorite-planet came to earth at Canyon Diablo. ”

“ Nearly all of the iron meteorite that was found by the farmer near Pittsburgh was worked up by a blacksmith and lost to science. Even the stone meteorites have occasionally fallen victims to man’s greed for gold. Miners who believed that the 80-pound San Emigdio, California, stony meteorite was gold-bearing mashed it to powder in an ore-crusher.
On the contrary, people who, in one way or another, have become acquainted with the characteristics of meteorites have brought a number of these objects to the attention of scientists. ”

“ Even the largest mass of the Norton meteorite merely buried itself in a funnel-like hole only about 10 feet deep. And the Russian investigators found a number of the lighter Ussuri fragments at the bottom of small penetration funnels. Cosmic missiles that are large enough to blast out craters in the ground are of particular interest to science, however, not only because of the extraordinarily intense light, sound, and other effects that accompany their fall, but also because they produce characteristic and long-lasting basin-like features in the outer shell of the earth. ”