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If you are not located in the United States, you'll have -to check the laws of the country where you are located before using this ebook. - -Title: Space Nomads - Meteorites in Sky, Field, and Laboratory - -Author: Lincoln LaPaz - Leota Jean LaPaz - -Release Date: August 18, 2016 [EBook #52848] - -Language: English - -Character set encoding: UTF-8 - -*** START OF THIS PROJECT GUTENBERG EBOOK SPACE NOMADS *** - - - - -Produced by Stephen Hutcheson, Dave Morgan, and the Online -Distributed Proofreading Team at http://www.pgdp.net - - - - - - - - - - LINCOLN LAPAZ - AND JEAN LAPAZ - - - - - SPACE - NOMADS - METEORITES IN SKY, - FIELD, & LABORATORY - - - HOLIDAY HOUSE, NEW YORK - - COPYRIGHT, 1961, BY LINCOLN LaPAZ & JEAN LaPAZ - PRINTED IN THE U.S.A. - - [Illustration: COURTESY OF AMERICAN MUSEUM OF NATURAL HISTORY - Fireball speeding across field of camera during the photographing - of the Great Spiral Nebula in Andromeda, by Josef Klepesta, at the - Prague Observatory, Czechoslovakia, September 12, 1923.] - - - - - PREFACE - - -Meteoritics is the study of the only tangible entities that reach us -from outer space. Except for the meteorites, scientists have to depend -entirely on studies of some form of _radiation_ for all their knowledge -of the wider cosmos lying outside of the atmosphere of the earth. And -none of the radiations reaching us from various sources afar can be held -in the hand for examination. 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. - -But the meteorites require no such temperamental instruments for their -measurement. They are themselves a permanent record. They can be -weighed, sectioned, and polished. They can be studied chemically, -microscopically, and radiometrically. In fact, they can be investigated -_directly_, just as they are themselves, in our hands, by any method -modern science may be clever enough to devise. - -This is why, now with the world’s attention drawn to ambitious plans for -the exploration of the cosmos, meteors and meteorites are of increasing -interest and importance. - -We have planned and written this book to be a sound and yet largely -nontechnical introduction to the science of meteoritics. Our daily -experiences in the Institute of Meteoritics have afforded us a fortunate -advantage in making such a presentation. For, in addition to our work in -the field, laboratory, and classrooms, we have frequently conducted -young people through the museum and workrooms of the Institute and so -have had the opportunity of learning their point of view at the same -time they were venturing into ours. 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. - -Although all photographs and special depictions not made by our staff -are individually credited, we wish to express our personal thanks for -the privilege of reprinting them here. All photographs that are without -a credit line have been made by members of our staff. - -_Lincoln LaPaz_ _Jean LaPaz__University of New Mexico, Albuquerque, -March 20, 1961_ - - - - - TABLE OF CONTENTS - - - PREFACE 5 - 1. A METEORITE FALLS IN THE TAIGA, U.S.S.R. 11 - 2. A METEORITE FALLS IN THE WHEATLAND, U.S.A. 23 - 3. FOUND AND LOST GIANTS 36 - 4. WHEN IS A CRATER A METEORITE CRATER? 42 - 5. HEAVEN KNOWS WHERE OR WHEN 66 - 6. FINDERS FOOLISH, FINDERS WISE 75 - 7. LANDMARKS, SKYMARKS, & DETECTORS 84 - 8. THE NATURE OF METEORS 101 - 9. THE NATURE OF METEORITES 118 - 10. TEKTITES, IMPACTITES, & “FOSSIL” METEORITES 134 - 11. OMENS AND FANTASIES 147 - 12. THE MODERN VIEW 158 - 13. PRESENT AND FUTURE APPLICATIONS 166 - FOR FURTHER READING 177 - INDEX 181 - - - - - SPACE NOMADS - METEORITES IN SKY, FIELD, & LABORATORY - - - [Illustration: Painting of the Ussuri fireball by the Iman artist, - P. I. Medvedev.] - - - - - 1. A METEORITE FALLS IN THE TAIGA, U.S.S.R. - - -The morning of February 12, 1947, dawned cold but bright and sunny in -the wide Ussuri valley of Eastern Siberia. During the early morning -hours the people in the villages went about their everyday chores as -usual. Farmers fed and watered their livestock, while housewives tidied -rooms and fired up stoves for heating and baking. Miners went to work -deep underground. An artist seated himself outdoors near his home to -make exercise sketches. In a densely wooded area on the slopes of a -nearby mountain range, a logging crew began a day’s timber-cutting. - -Suddenly, at 10:35 a.m., an extraordinarily large and brilliant fireball -flashed above the central part of the mountain range. It streaked across -the sky in less than 5 seconds and disappeared beyond the western -foothills of the range. Then the inhabitants of a wide area heard what -seemed to them a mighty thunderclap followed by a powerful roar like an -artillery cannonade. Many people felt a strong airwave. (Field parties -later found that those who noticed this effect were quite close to the -place where the meteorite fell.) - -For several hours afterward, a large black column of smoke tinged with a -reddish-rose color stood above the place of fall. Gradually, this cloud -spread outward, became curved and then zigzag in form, and finally -vanished toward the end of the day. - -The flash of the fireball and the loud noises that followed it caused -panic among the farm animals. Cows lowed mournfully and herds of goats -scattered in every direction, chickens and other fowl squawked in alarm, -and dogs ran whining for shelter or crouched against the legs of their -masters. - -In the villages, the airwave blew snow off the roofs of houses and other -buildings, while the strong earth-shocks opened windows and made doors -swing ajar. Housewives were dismayed to see glass windowpanes shattered -in their frames and burning coals and firebrands jolted out of the -wood-burning stoves. - -Even deep in the mineshaft, the vibrations in the air were strong enough -to snuff out the miners’ lamps, leaving the men in darkness. - -On seeing the huge fireball streak across the sky, the artist put aside -his practice sketch and began a picture of the display before his -impressions of it could fade. His painting of this natural event is now -famous. Not only is it on display in scientific museums all around the -world, but a color reproduction of it has been issued in Russia as a -postage stamp. - -The forester supervising the logging crew reported that his attention -was first attracted to the sky when he noticed a strange “second” shadow -rotating rapidly about the tree that cast it. On looking up, he saw a -blindingly bright fireball, twice as large as the sun, a fiery globe -that threw off multicolored sparks as it passed. Not long after the -fireball disappeared behind the trees, the forester heard a loud noise -like nearby cannonading and saw a large dark-colored cloud—later tinged -with red—billow up over the impact point. (The members of the logging -crew were among the very few persons actually abroad near the place of -fall. It turned out that they were only about 9 miles from it.) - -As soon as the many eyewitnesses of the fireball had recovered from -their fright, the questions almost everyone asked were “What could it -have been?” and “Where did it come down?” To answer the first question -was not as difficult as to answer the second. Local scientists in -Vladivostok and Khabarovsk, the nearest cities of some size, suspected -from the first that a very large meteorite fall had occurred. But -exactly where? All they could be certain of was that the impact point -lay in the Ussuri taiga, a formidable wilderness. - -The Sikhote-Alin mountains lie along the Siberian coast between the Sea -of Japan and the Tatar Strait. The Ussuri taiga is a vast, low-lying, -marshy, densely forested region fronting the western flanks of these -mountains. Ordinary cedars, pines, oaks, and aspen grow in the taiga, -but the region is also noted for such rare plants and trees as the -celebrated ginseng, the cork tree, the Greek nut tree, and the black -birch. Wild grape and ivy vines intertwine the upper branches of the -thick forest, and the trunks of the trees themselves rise from an almost -impenetrable maze of brush and downed timber. - -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 it is now -known in the U.S.S.R.) Sikhote-Alin meteorite, had chanced to fall. For -any search parties traveling on the ground, the likelihood that they -could find the fallen meteorite in that wilderness would have been very -small. - -The impact point of the Ussuri meteorite was discovered in the only way -really practical: from the air. Fortunately, the center of impact lay -almost directly below the airlane connecting the towns of Iman and -Ulunga, so that the devastation produced by the meteorite fall in the -taiga was clearly visible to aviators following this active air route. - -The accounts several fliers gave concerning the widespread cratering and -destruction they had seen from the air in the impact area led to the -organization of two separate ground-search parties, one at Khabarovsk, -the other at Vladivostok. The Khabarovsk group, made up of four members -of the Geological Society, flew to the village of Kharkovo, the -inhabited point nearest the site of fall. After a rough and dangerous -landing on the small, snow-covered airfield at Kharkovo, the geologists -began their trek into the taiga on foot. Throughout the entire trip, the -men, burdened with supplies and equipment, waded through waist-deep snow -and camped in the open despite the arctic cold. - -At almost the same time, a geologist from Vladivostok set out from the -railway line up the Ussuri valley to track down the fallen meteorite. -His progress was even more difficult than that of the Khabarovsk party. -In addition to following a much longer route, he did not have the -invaluable information that the first party had got from the aviators. -He had to make his way slowly from village to village, questioning -eyewitnesses as he went and gradually determining the probable end-point -of the meteorite fall. - - [Illustration: COURTESY OF E. L. KRINOV - Splintered and broken trees at the site of the Ussuri fall.] - -The route followed by the Vladivostok geologist lay through the heart of -the trackless snow-covered taiga. Fortunately, he had with him two -hunters who were well acquainted with the rigors of travel through the -taiga and knew how to live off the land. - -They slept in hunters’ huts or under overhanging trees, drank melted -snow water, and ate fried quail. But they had not gone far when they -found that their footwear was completely useless for a trek through the -wet, snowy taiga, because their felt hiking boots quickly soaked up -water and became very heavy. So they swathed their feet in warm dry -grass over which they tied large pieces of untanned leather. After that, -the walking was much easier. They were able to cover the ground so -rapidly that they reached Kharkovo only a day after the Khabarovsk -geologists had landed there at the small airfield. - -At Kharkovo, the three feasted on pork, milk, and honey. Then loading a -few provisions on a borrowed horse, they started out to overtake the -Khabarovsk party. They made such good time that the two groups were able -to join forces and to enter the impact area as one expedition, on -February 24, 1947. - -A scene of great desolation awaited them in the central region of the -meteorite fall. Masses of crushed stone had been hurled hundreds of feet -by the violent impact. Denuded, uprooted trees lay about—some cut in two -as neatly as if by a saw. Large cedars had been splintered where they -stood or had been torn up by the roots and thrown some scores of yards. - - [Illustration: COURTESY OF E. L. KRINOV - Workmen excavating one of the large craters formed by the impact of - the Ussuri meteorites.] - -Most impressive of all, though, were the numerous meteorite craters -ranging in size from small bowl-like features to a basin more than 28 -yards across and over 6 yards deep—a depression large enough to hold a -two-story house. The investigators recovered many fragments of the iron -meteorite that had broken to pieces not far above the earth’s surface -and had peppered the area of fall with high-speed meteoritic “shrapnel.” - -With their meteorite recoveries and photographs of the cratered area, -the members of this first expedition returned to their respective towns -and began a campaign by letter and wire to interest the Moscow office of -the Academy of Sciences of the U.S.S.R. in making a full-scale -investigation of the Ussuri fall. The officials of the Academy decided -at once to send a special scientific expedition to the site of the -meteorite fall. - -A member of this later and better-equipped expedition compared the -Ussuri crater field to a bombed-out area. In fact, some of the meteorite -specimens were fragments that closely resembled pieces of shattered -shell-casing. The edges of these fragments were jagged and bent, and -their surfaces, which often displayed a rainbow-colored sheen, were -grooved and scarred by impact against the hard rock underlying the -region in which the crater field had been formed. In rare instances, the -investigators noted spiral twisting of the fragments, an indication of -the unusually violent disruptive forces to which they had been subjected -at impact. - -The scientists found several instances in which fist-sized meteorite -fragments had actually penetrated into or through standing tree trunks, -either becoming imbedded in the wood or driving a hole right through the -trunk. - - [Illustration: COURTESY OF E. L. KRINOV - A nickel-iron meteorite from the Ussuri fall imbedded in the trunk - of a cedar tree.] - -Many whole individual meteorites also were recovered. These were almost -always covered by a thin, smooth “glaze” known as _fusion crust_. This -crust forms on the surface of a meteorite as it plunges rapidly through -the air. The heat generated during its flight causes the outer “skin” of -the meteorite to melt. Later, when the mass has cooled off, the thin -coating of melted material hardens, forming a rind or crust. - -By the beginning of 1951, the Russians had sent three more expeditions -to the site of the Ussuri fall. Their scientists found, in all, 122 -craters (the largest more than 80 feet in diameter) as well as numerous -funnels resulting from the penetration of smaller meteorites into the -earth. By means of both visual and instrumental searches, they also -recovered 20,000 meteoritic fragments and individual meteorites. The -smallest Ussuri specimens weighed no more than the thousandth part of a -gram. (There are 453.59 grams in a pound.) Some of these tiny masses -were found lying cupped in leaves. The largest individual meteorite -recovered weighed about 3,839 pounds. Altogether, approximately 23 tons -of meteoritic material from the Ussuri fall are now in the collection of -the Meteorite Committee of the Academy of Sciences, Moscow, while -another 47 tons are believed to still be buried in the Ussuri crater -field. - - [Illustration: COURTESY OF E. L. KRINOV - An individual Ussuri meteorite with fusion crust and characteristic - surface sculpturing produced during high-speed flight through the - resisting atmosphere.] - -The Russian scientists carefully mapped the locations of the individual -craters, penetration funnels, and meteorite recoveries. They made -geologic and magnetometric surveys of the crater field, took aerial -photographs of the entire area of fall, and prepared a documentary -motion-picture covering the activities of the various expeditions. The -area of the crater field has been set aside by the Russian government as -a sort of scientific preserve, and is being made into the equivalent of -what is termed a National Monument in the U.S.A. Several of the typical -craters are protected by overroofed shelters to preserve these features -for generations yet to come. - - - - - 2. A METEORITE FALLS IN THE WHEATLAND, U.S.A. - - -February 18, 1948, had been a pleasant day in northwestern Kansas and as -the supper hour approached, the sky remained blue and cloudless. Shortly -before 5:00 p.m., a few people were still out of doors. An eleven-year -old girl was hanging up the last of the family wash on a high -clothesline. In the late afternoon sunshine, a woman and her son were -enjoying a walk around the back yard of their home on a large Kansas -ranch. Outside his house, a ten-year old boy was playing basketball with -friends. A veteran of World War II was loading fodder in a silo. In the -feedlot of his ranch, a farmer was stacking hay. A filling station -attendant was working outside at the pumps, grateful for a spell of -milder winter weather. - -Without warning, a large and very bright fireball streaked across the -clear sky from southwest to northeast. Ominous-looking white -smoke-clouds mushroomed up from points in the fireball’s path. Shortly -after the fireball disappeared, loud explosions and rumbling sounds -drove thousands of people out into the open. The whole astonishing -luminous display was over in a few seconds, but the strange clouds and -the frightening sounds that followed the fireball’s passage continued -much longer. - -Although startled by the brilliant fireball and the strange thundering -noises, the young girl, whose face had been turned skyward as she hung -up the clothes, noted very carefully where she had seen the fireball -disappear behind the tallest building in her home town. (Her sighting -was later of great value to field parties from the Institute of -Meteoritics of the University of New Mexico.) - -The woman and her son were amazed to see an angry, boiling white cloud -tinged with red developing overhead in the blue sky and to hear strange -whizzing noises in the air around them. - -The boy playing basketball heard a peculiar whistling or hissing noise -just as he was ready to shoot a basket and, on looking up, saw the ball -of fire slanting earthward. (This boy’s report was of particular -interest, since it related to an unusual type of “sound” that travels at -the speed of light rather than at the velocity of ordinary soundwaves.) - -As a cannonading louder than any the veteran had heard on the -battlefields of Europe echoed over the rolling countryside, he went -temporarily into a state of shock. - -The farmer stacking hay heard several explosions, felt a violent air -blast, and finally heard a solid object strike the ground “with a -smack,” as he put it, “like a clod hitting the earth.” (Later, field -searchers found that this man lived only about two and a half miles -south of the point where the largest fragment of the meteorite fell.) - -Shortly after the passage of the fireball, the filling station attendant -felt the legs of his trousers flap as if he were standing in a high -wind, although he was more than 11 miles distant from the actual path -along which the fireball moved on its way to the earth. - -As in the case of the Ussuri fall, which had occurred about a year -earlier, farm animals, chickens, and dogs were terrified by the strange -and noisy event. Cattle tried to run through a fence to escape the -deafening racket. A fine pair of horses panicked and ran headlong into a -narrow gully, the walls of which collapsed on them during their -struggles. Chickens dashed for the henhouse, screeching and cackling all -the way. A dog that feared lightning jumped behind a haystack and -finally ran to his master in alarm. - -Although the majority of the people did not see the fireball itself, -they were driven out-of-doors by the violent concussions that followed -its passage, and thus got out under the open sky in ample time to see -several large, turbulent white clouds mushrooming far overhead. From -these clouds, a thick powder or dust filtered down through the air and -collected on the surfaces of stock ponds and water tanks. - -Some people thought the peculiar clouds were similar to those produced -by atom bomb explosions. Many suspected that a V-2 rocket had “run away” -from the proving ground at White Sands, New Mexico. One man disagreed -with the opinion of his friends that the military had been experimenting -and declared that it was “the Lord who was experimenting!” - -The February 18 meteorite fall caused great excitement throughout Kansas -and Nebraska, and it was the chief topic of conversation for days among -the residents of the many small farming communities along the western -half of the Kansas-Nebraska state line. - -The Ussuri fall was studied by Russian scientists exclusively, and we -have of necessity given, in Chapter 1, a secondhand account of the fall -and surveys the Russians made; but field parties from the Institute of -Meteoritics conducted on-the-spot investigations of the Norton, Kansas -fall. As we were members of several of these field parties, the story to -follow is a firsthand report. - -A little before 6:00 p.m. on February 18, word of the mysterious -explosion centering near Norton, Kansas reached the Institute of -Meteoritics, in Albuquerque, N. M., through the kind offices of Civil -Air Patrol personnel. Since a number of early reports had described the -incident as an airplane falling in flames, it was only natural that the -Civil Air Patrol and similar groups would take an interest in the -occurrence. At once, the staff of the Institute began to interview -eyewitnesses of the event through Civil Air Patrol channels and by long -distance telephone, telegram, and letter. Soon we had collected enough -information to show clearly that a large meteorite fall had been -responsible for the unusual light and sound effects that had startled -the inhabitants of Kansas, Nebraska, and adjoining states. - -By March 3, the Institute staff had made a first determination of the -probable area of fall. The center of this oval-shaped, 8 by 4 mile area -lay about 15 miles north-northwest of Norton, Kansas and nearly on the -Kansas-Nebraska state line. The meteorite had fallen in a region of -wheat fields, pasture lands, and widely scattered farm houses. The -countryside there is open and gently rolling. The small creeks winding -through shallow valleys are marked in spring and summer by narrow bands -of low green trees and bushes. Many of the hillsides are covered with -unplowed buffalo sod. - - [Illustration: A fragment of the Norton fall is removed still - imbedded in the tough buffalo grass sod into which it penetrated.] - -On March 24, a field party left the University of New Mexico to make a -survey of this area. Unfortunately, Kansas blizzards can be as severe as -any in Siberia, and although the scientists gathered many helpful -reports from eyewitnesses of the fall, heavy snow and high winds -seriously hampered the work. The information they collected, however, -confirmed the accuracy of the Institute staff’s first determination of -the probable area of fall. - -Late in the spring, a farmer in this area found a “strange stone” on his -land and held it for identification by the second Institute party. This -strange stone—which smelled like sulfur and had metallic specks in -it—was the first piece of the fallen meteorite to be recovered. - -Scientists and farmers soon found many other fragments during systematic -searches of the rolling farm and pasture lands. The fourteen-year-old -boy who had been walking with his mother at the time of the fall -discovered a 130-pound fragment of the meteorite in a pasture that had -already been carefully searched by grown-up meteorite hunters! This find -was one of the two largest fragments recovered from the entire fall. The -landing place of this large piece was marked only by a small hole in the -sod, but, on prodding into this hole, the boy struck something rather -solid. He ran at once to tell the lady who owned the pastureland, and -together they dug out the fine meteorite. - - [Illustration: The Furnas County, Nebraska, stony meteorite in place - at the bottom of its 10-foot “penetration funnel.”] - -This discovery brought interest in finding meteorites to a fever pitch, -and it was soon possible to look in almost any direction and see -farmers, or their wives and children, walking slowly across the fields -and looking for meteorites. - -Finally, in August, two farmers cutting wheat in a field just a short -distance north of the Kansas-Nebraska state line found a deep hole when -their tractor almost fell into it. They investigated and discovered that -a very large fragment of the meteorite had buried itself deep in the -ground. - -Scientists from the University of Nebraska and the Institute of -Meteoritics carefully excavated this huge meteorite. They found that the -mass had plunged more than 10 feet into the earth. Quite by chance, its -lower surface had come to rest in the ashes of a long-buried primitive -cooking site. - -The excavated meteorite looked and felt like a huge stone. Actually, it -was stony in nature, but of a texture so fragile that it had to be -wrapped in tissue paper, then in burlap, and finally covered with a -thick coating of plaster of Paris before it could be lifted out of the -ground. Those in charge of the removal of the meteorite borrowed this -procedure from the paleontologists, who use it in the removal of fossil -tusks and bones that otherwise would crumble away. - -After the great meteorite had been raised out of the excavation, it was -taken by truck to the University of New Mexico, in Albuquerque. There it -was put on display beside the smaller 130-pound fragment found in May. -By careful measurements, scientists determined the weight of the main -mass to be approximately 2,360 pounds—a record weight for stony -meteorites.[1] This remarkable meteorite, known as the Furnas County, -Nebraska, stone, is now a prized item in the collection of the Institute -of Meteoritics. - - [Illustration: Field party proudly surrounds the Furnas stone in its - protective “armor.”] - -As more and more finds were made in the area of fall, we accurately -recorded their weights and mapped their locations. In this way, we could -tell how the pieces of the meteorite had distributed themselves -according to size and weight over the oval-shaped area. The smaller and -lighter fragments were slowed down by air resistance and fell first, -while the 2,360-pound mass carried on beyond them and came to earth at -the farthest point along the direction of flight. - -The staff of the Institute took many photographs of the meteorites that -were found, of the impact funnel made by the largest mass, and of the -excavation and removal of that giant stone. Some of these pictures were -published in scientific journals, others in magazine and newspaper -articles. A few of our best photographs are included in this chapter. - -Although the light and sound effects that accompanied the Ussuri and -Norton falls were similar, the meteorites recovered from them were not -at all alike. The Ussuri specimens were masses of nickel-iron so -malleable that on high-speed impact with hard rock they had held -together and taken twisted and ragged shapes. But the Norton meteorites -were very fragile stony masses, many of which went to pieces either in -the air or when they struck the ground. Almost all of the recoveries -made of this very rare type of stony meteorite were fragments, not whole -specimens. They somewhat resembled pieces of a strange whitish mixture -of chalk and crystalline limestone containing tiny specks and lumps of -nickel-iron. Many specimens were covered wholly or in part by a shiny -varnish-like fusion crust, varying in color from jet black through -yellow to almost pure white. - - [Illustration: The Furnas stone, protected by its “armor,” hangs - suspended from the truck crane that raised it out of its deep - “penetration funnel” in the earth.] - -The largest meteorite recovered from the Norton fall was the 2,360-pound -mass that formed the deep impact funnel. The smallest Norton specimens, -like their Ussuri counterparts, weighed no more than the thousandth part -of a gram. Altogether, nearly a ton and a half of meteoritic material -from the Norton fall was collected by the Institute. Other small -fragments may remain undiscovered in the Kansas and Nebraska wheatlands, -but, unfortunately, because of the soft and fragile nature of the -material they are composed of, it is likely that they have now weathered -away so completely that they are no longer recognizable as meteorites. - -Our stories of the Ussuri and Norton meteorite falls show how hard -scientists work themselves (and others!) to find meteorites. Therefore -meteorites must be important. The two accounts given also make clear -that investigators of meteorite falls are almost entirely dependent upon -observations made by nonscientists. - -Scientists investigating meteorite falls greatly appreciate the help -given them by children and adults alike. Field parties are powerless -without it, and we should like to encourage people of all ages to -continue this type of valuable cooperation. In Chapter 7, we shall tell -more about how the individual observer of a meteorite fall can make his -report really count. - - [Illustration: A close-up of the Furnas County stone, the largest - stony meteorite ever recovered.] - - - - - 3. FOUND AND LOST GIANTS - - -All meteorites are important from the standpoint of science, but a few -deserve special mention because of the human-interest stories connected -with them. - -First place among famous finds should no doubt go to the massive Cape -York, Greenland, iron, the largest recovered meteorite actually to have -been weighed. The Eskimos called this enormous object “Ahnighito,” which -means “The Tent.” Robert E. Peary, the discoverer of the North Pole, -brought it to New York City by ship in 1897. His party had great -difficulty hoisting the 34-ton mass aboard. Later, when the ship had put -to sea, she encountered a serious navigational hazard. To the amazement -and alarm of the crew, the huge nickel-iron meteorite caused magnetic -disturbances that severely affected the ship’s compass. - -Another of the giant meteorites, the 14-ton Willamette, Oregon, iron, -became the center of a long legal battle in the early 1900’s. The man -who originally found the meteorite and recognized its true nature felt -that because the iron was on the surface of the ground and not buried -beneath it (as the ore of a metal would have been), there was no reason -why he should not move the mass from the place of find to his own -property, three-fourths of a mile away. He did this very laboriously by -means of a log-timber car, a capstan with wire rope, and a small horse. -On learning what the finder had done, the company that owned the land -from which the meteorite had been removed put its attorneys on the job -of recovering the “purloined” meteorite. The Oregon courts, bowing to -decisions made in previous cases involving ownership of meteorites, -brought in a verdict favoring the owners of the land. Although the -finder of the Willamette meteorite lost the decision, he nevertheless -won the distinction of being the only man to have successfully made off -with a treasure weighing 14 tons! - - [Illustration: COURTESY OF AMERICAN MUSEUM OF NATURAL HISTORY - Peary’s photograph of the Cape York meteorite as it was being moved - for loading aboard his ship.] - - [Illustration: COURTESY OF AMERICAN MUSEUM OF NATURAL HISTORY - Arrival of the 34-ton iron mass at the American Museum of Natural - History, New York City.] - -The biggest meteorite of all, of course, is the one that “got away.” In -1916, a captain in the Mauritanian army was taken by a native guide, -secretly and at night, to the site of a colossal iron meteorite located -in the dunes of the Adrar desert, in the far western reaches of the vast -Sahara. The officer described the mass as measuring 100 meters (over 300 -feet) by 40 meters (over 120 feet), with the third dimension hidden by -the sand dunes. According to him, the mass “... jutted up in the midst -of sand dunes that were covered by a desert plant, the _sba_, and it had -the form of a compact, unfissured parallelopiped. The visible portion of -the surface was vertical, dominating in the manner of a cliff, the -wind-blown sand that was scooped away from the base of the mass so that -the summit overhung; and that portion exposed to eolian [wind] erosion -was polished like a mirror.” - -The captain, at the request of his uneasy guide, returned from his -hurried excursion without taking notes or making a map. But he did bring -back a small 10-pound fragment of iron which he had found lying on top -of the giant mass. This small fragment later proved to be a genuine -meteorite, and is the only known specimen of the famous Adrar mass. It -is preserved at present in the Museum of Natural History at Paris. - - [Illustration: J. OTIS WHEELOCK PHOTO - COURTESY OF AMERICAN MUSEUM OF NATURAL HISTORY - Man and boy carrying off the famous “purloined” Willamette - meteorite on a homemade dolly car with wheels of tree-trunk - sections. Note hole piercing this 14-ton chunk of iron.] - -What has been called a conspiracy of silence among the natives of the -Adrar area and the inhospitable nature of the region itself have -successfully preserved the secret of the location of the enormous -metallic mass described by the captain. The native guide died, -apparently of poison, and although many inhabitants of the region are no -doubt familiar with the whereabouts of the mass (whatever it is!), those -questioned have consistently denied knowledge of its very existence. All -recent attempts, not only by military but even by scientific -expeditions, to relocate the gigantic metallic mass have failed. The -whole Adrar case remains an intriguing puzzle to be unraveled, it is -hoped, by future generations of meteorite hunters. - -Another “lost” meteorite is one composed of stone and iron. The Port -Orford, Oregon, stony-iron (as it is now named) was originally found in -1859 by a U.S. geologist who was engaged in a survey of what were then -the Oregon and Washington Territories. According to him, the mass was -quite irregular in shape and “4 or 5 feet [of it] projected from the -surface of the mountain,” while it was “about the same number of feet in -width and perhaps 3 or 4 feet in thickness.” He broke off a small -fragment of it (far smaller than the one taken from Adrar) and packed -this specimen away with his collection of rock and mineral samples. -Years later, the geological collection was cataloged and analyzed in the -East. At that time, the fragment collected in 1859 was found to be a -piece of a stony-iron meteorite. After that, scientists and others made -many attempts to rediscover the main mass of the large Port Orford -meteorite, all of them unsuccessful. Today the sum total of material -recovered from this stony-iron amounts to 25 grams in the U.S. National -Museum, about 4 grams in the Natural History Museum of Vienna, and a few -tiny specks in the Museum of the Geological Survey of India. - -The Red River, Texas, iron is still another famous meteorite. It was -originally discovered by Pawnee and Hietan Indians, and a group of them -took a party of traders, in 1808, to the site. Two years later, two -rival parties, each led by a man who had been a member of the 1808 -trading expedition, began a search for the meteorite. The members of one -of the two parties were from Nacogodoches, Texas. They reached the -meteorite first but had left home so hurriedly on their eager hunt that -they were not properly prepared to move so large a mass. They went away -from the site to get horses and a wagon, after they had laboriously -hidden the meteorite under a huge flat stone, to prevent the other party -from finding it. The members of the other party, hailing from -Natchitoches, Louisiana, set out better prepared. After a lengthy hunt, -they finally found the hidden meteorite. Using tools they had the -foresight to bring, they built a truck wagon and drove away with their -prize. Eventually, the Red River meteorite, weighing 1,635 pounds, -became a part of the collection at Yale University. But two other, -smaller, masses of the same metal, known in the early days to the -Pawnees and a few traders, remain still undiscovered in the Red River -area. - - - - - 4. WHEN IS A CRATER A METEORITE CRATER? - - -Not all meteorites form craters at impact, as the larger Ussuri -fragments did. 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. - -Natural processes that change the surface features of the earth have -long been the subjects of field studies by scientists. Geologists have -carefully investigated the major folds formed in the earth’s crust by -mountain-building forces, the clefts and depressions resulting from -earthquake activity and erosion, and the vast plains leveled off by the -scouring action of great ice-sheets. All of these different natural -processes, though, have one thing in common: their source is the -earth-body itself. They take place either _within_ the earth’s crust as -a result of local shifts or changes in pressure (like earthquakes and -volcanic eruptions), or _on_ the surface of the earth as a result of the -action of water or of changes in temperature (like erosion and -glaciation). - -On the other hand, meteorite impact craters are not formed by -earth-processes at all. As we have seen, they result when large bodies -of matter from the regions of space _outside_ the earth chance to strike -the surface of our planet at high speed. The study of meteorite craters -is therefore a special field. It is also one of quite recent -development; not until 1905 was the first meteorite crater recognized as -such. - -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. Many such sinks surround the -genuine meteorite crater near Odessa, Texas, and at times have been -mistaken for the real thing. - -Since there is some possibility of confusion about whether or not a hole -in the ground is a meteorite crater, it is comforting to know that -scientists have come up with a handy set of rules for reaching a -decision on this point. These rules can be stated in the form of several -questions that crater-investigators should ask themselves: - - Have you found meteorites in or near the crater-like feature? - - In its vicinity, have you found pieces of country rock that show the - effects of high temperature and pressure (melting or crushing)? - - Did people actually see a meteorite come to earth at the point where - the crater is located and where, to their certain knowledge, no crater - existed before? - -If the answer to all—or even one—of these questions is yes, then it is -quite likely that the crater-like feature is actually a meteorite -crater. Naturally, if the answer to the _first_ question is yes, the -matter is practically settled in favor of the meteoritic origin of the -feature. - -If the impact has taken place in horizontally bedded rock strata—that -is, in flat beds of rock lying one on top of another like the layers in -a stack of griddle cakes—a meteorite crater will have a characteristic -_rim_ of upturned or even overturned rock layers. (None of the ordinary -sink holes near the Odessa crater show such rims.) In addition, pieces -of rock shattered and thrown out by the impact will be found in all -directions around the crater. The amount and size of this fragmented -material will decrease with distance outward from the crater. - -A list of the recognized (or genuine) meteorite craters of the world is -given in the table on page 65. All of these craters except the two -Russian ones were formed many thousands of years ago, and, in most -cases, the earth processes of erosion and weathering have by now dimmed -the sharp outlines of their rims and silted up their deep interior -funnels until only basin-like bowls remain. - - [Illustration: Cross-section showing the manner in which - horizontally bedded rock strata may be broken and tilted upward by - the impact of a crater-forming meteorite. This schematic diagram is - based on excavations at several meteorite craters.] - -You may have visited the very first crater in the world to be recognized -by scientists as a meteorite crater. This huge basin, now known as the -Canyon Diablo meteorite crater (although often referred to incorrectly -as “Meteor Crater”), lies about 20 miles west of Winslow, Arizona. It is -the best known of all the craters listed in the table because in recent -years it has been developed under private ownership as one of the -leading tourist attractions on U.S. Highway 66. - -From the paved road that turns off Highway 66 toward the crater, the -visitor sees the rim as a chain of low, hummocky, tan-colored hills -which contrast sharply with the grayish or reddish hue of the desert -plain. - -The outer slopes of the crater rim rise very gently from the level plain -in which the crater was formed, and they are covered with rock fragments -of various sizes thrown out at the time the meteorite struck the earth. -This fragmented material ranges in size from tiny particles of -“rock-flour” as soft as face-powder to gigantic solid masses like -Monument Rock, which is estimated to weigh 4,000 tons. - -Field parties have found 50- to 100-pound fragments of the limestone -layer underlying the Canyon Diablo area at distances of 1½ to 2 miles -from the crater. Sizable rock and meteorite fragments out to distances -of 6 miles from the rim have turned up, and smaller fragments of both -materials at even greater distances. - -On their first visit to the Canyon Diablo crater, people are always -astonished at the steepness of the inner walls of the crater and at the -very great size of its bowl. This crater is more than 4,000 feet across -and 570 feet deep. It is the largest _recognized_ meteorite crater so -far discovered in the world, although other larger, basin-like features -elsewhere on the surface of the earth have been suspected but not proved -to have a similar origin. - - [Illustration: COURTESY OF TRANS-WORLD AIRLINES - Aerial view of the Canyon Diablo, Arizona, meteorite crater.] - -When the Canyon Diablo meteorite plunged into the horizontally bedded -rock layers underlying the area of fall, the force of the explosion -following the impact actually bent these layers upward. All around the -inside of the crater, the rock strata tilt away from the center at steep -angles. - -Cowboys, ranchers, and scientists have found thousands of solid -nickel-iron meteorite fragments around the crater. The largest of these -weighs 1,406 pounds. The smallest spherules and grains are almost or -quite microscopic in size. (These tiny granules have been well known to -scientists since 1905 in spite of current fables claiming that they are -a recent discovery.) In the rim and on the plain outside the crater, -large and small _shale balls_, composed of weathered meteoritic -material, were found in considerable numbers in the early days. Along -with many solid iron meteorites, shale balls have also been found at -various depths in recent times by field parties from the Institute -employing specially designed meteorite detectors. - -In the first two decades of the twentieth century, investigators sank -(at great expense!) a number of shafts and drill holes in the interior -and on the south rim of the crater, in unsuccessful attempts to locate -the supposed “main mass” of the Canyon Diablo meteorite. Most -authorities now believe, however, that the extremely high temperatures, -developed at the time the Canyon Diablo meteorite penetrated into the -earth, changed almost all of the gigantic cosmic missile into vapor. - - [Illustration: View of the interior of the Canyon Diablo crater - showing the steep inner slopes of the huge basin.] - -No better example of an ancient meteorite crater has been found than -this one near Canyon Diablo. The other craters listed in the table (even -the two recently formed ones), while bearing resemblances to it, also -show individual differences from it. - -Some, like Henbury, Campo del Cielo, and Haviland, are not single -craters but rather consist of fields of craters. In these cases, the -earth was struck not by a single large meteoritic body that held -together right down to impact, but either by a “swarm” of meteorites -traveling together through space or by the fragments of a large -meteorite that separated into pieces shortly before it struck the -surface of the ground. - -Again, the type of ground into which the meteorite strikes affects the -character of the craters formed. As an illustration, the Wabar, Arabia, -craters were not smashed out of sedimentary, horizontally bedded rock -layers (as was the Canyon Diablo crater) but were formed in clean desert -sand dunes. In this case, the crater rims are composed primarily of -almost pure silica-glass formed by the fusion of the sand at the time of -impact. It is not hard to imagine the terrific boiling and frothing up -of melted sand and meteoritic material that must have accompanied the -formation of the Wabar craters. - -Except for Podkamennaya Tunguska and Ussuri, the craters listed in the -table were formed, as we have mentioned, a great many thousands of years -in the past. Just how many thousands is a difficult question to answer, -for all of our estimates must necessarily be made on the basis of -_indirect_ evidence rather than on _direct_ observation. - - [Illustration: Before impact of Canyon Diablo meteorite, these rock - layers were horizontal.] - -Paleontologists, geologists, and other scientists give us an age of from -20,000 to 70,000 years for the Canyon Diablo crater. The discovery of -the fossil remains of a prehistoric horse buried in the Odessa, Texas, -crater fill has shown that the age of that crater is not less than -200,000 years. The oldest craters known in the United States are the -Haviland group produced by the Brenham, Kansas, meteorites. -Long-continued weathering has almost completely worn down the rims and -covered up the craters of this group. On the basis of the rate at which -nickel-oxide has spread out into the soil about a large deeply buried -Brenham meteorite, calculations carried out at the Institute of -Meteoritics have led to a tentative age of more than 600,000 years for -the Kansas craters. - -Perhaps the oldest meteorite crater of all is the one blasted into what -the geologists identify as pre-Cambrian quartzite at Wolf Creek, Western -Australia. Even the highly resistant iron meteorites found around this -crater have almost completely weathered away. Only tiny specks and thin -veinlets of metal are now visible on the cut surfaces of meteorites -that, untold hundreds of thousands of years ago, were solid masses of -nickel-iron. - -You may have noticed that the widely publicized circular, water-filled -Chubb crater in the Quebec Province of Canada was not included in the -table. This Canadian feature was left out because the answer to each of -the three questions listed earlier in this chapter is no. - - [Illustration: COURTESY OF WILLIAM A. CASSIDY - Two of the deeply weathered meteorites found at Wolf Creek crater - in western Australia.] - -The field parties that have carefully searched the Chubb crater and its -surroundings, even when they used one of the Institute’s powerful drag -magnets, were unable to find any trace whatever either of meteorites or -of such weathered remains of meteorites as show the true nature of the -Wolf Creek crater. Furthermore, no searcher has discovered any fragments -of ordinary rock showing the effects of the extreme heat and pressure -that accompany large-scale meteoritic impact. Finally, the meteorite -supposed by some to have produced the Chubb crater was not a recorded -witnessed fall, for the crater is of very ancient origin indeed. - -Perhaps further search of the Chubb crater site and especially of the -debris in its deep, water-filled interior will succeed in bringing to -light either specimens of meteorites or of silica-glass or other -products of meteoritic impact. If so, then and only then will -identification of the Canadian crater as a meteorite crater be -justified. - -Up to this point, we have talked only of very old meteorite craters. But -two crater-producing meteorite falls have occurred within this century, -both in Siberia. The Ussuri fall was one of these and the more recent of -the two. - -The earlier and more unusual fall took place on June 30, 1908, at about -8:00 a.m., approximately 40 miles northwest of the trading post of -Vanovara. A fireball exceeding the sun in brilliance flashed across the -sky and was followed by extremely violent airwaves and earth-tremors. - -The pressure wave in the atmosphere set up by this meteorite fall was -strong enough to damage roofs and doors of houses near the point of -impact, as for example, in the village of Vanovara. On both rivers and -lakes in the area of fall, the pressure wave in the air piled up high, -sharp-fronted water waves that resembled the bores on the Seine and -Severn and that upset fishing craft and swamped other small boats. -Throughout a wide region at somewhat greater distances from the impact -point, tidal-like bores were raised on rivers and lakes. So gigantic was -the atmospheric disturbance, that it was detected at almost every -station in the world where sufficiently sensitive barometers were in -operation. - -Eyewitnesses of this meteorite fall said that at the time the fireball -passed near them, they felt almost unbearable heat. - -A huge “fiery pillar” rose above the point of impact, which by good -fortune was in a desolate and almost uninhabited swampy basin between -the Chunya and the Podkamennaya (i.e., “Stony”) Tunguska rivers. The -meteorite fall takes its name from the latter stream. - -The central portion of the region of impact is marked not only by a -number of craters in the swampy terrain, but also by mute evidence of -the extraordinary destructive power of the Podkamennaya Tunguska -meteorite. Over an area of many square miles, the explosion blew down -the standing forest so that the tops of the overthrown trees (estimated -by the Russians to number more than 80,000,000!) all point away from the -impact center. The intense heat charred the trunks and branches of the -trees in this area in much the same way as the heat from the first of -all atomic bomb explosions scorched the desert shrubs around the test -site in south-central New Mexico. - -Within the area of fall, countless reindeer belonging to the native -Tunguse herdsmen were killed, only their charred carcasses remaining. -How great the heat released at impact was may be judged by the -well-established fact that the prized silver samovars of the nomads were -found melted amid the debris of their flattened camps. In at least one -instance, a Tunguse was so overcome by the terrible event he had -witnessed that he was “sick for a long time.” The whole impact-region -came to be considered as accursed by the natives, who abandoned the use -of all trails crossing it. - -For many years the Podkamennaya Tunguska fall was neglected, partly -because of the remoteness of the area in which it occurred, partly -because of unsettled conditions in Russia; but chiefly because, in -general, the Russian scientific and governmental officials simply did -not believe the “fantastic” tales concerning the fall told by the native -Tunguses, from which we have given a few details above. - -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! - -This strange circumstance led the senior author to suggest, in 1941, -that the almost incredible Podkamennaya Tunguska incident had resulted -from the infall of a meteorite that, together with an equivalent mass of -the earth-target, was transformed into energy upon contact with our -planet. How can such extraordinary behavior be accounted for? - - [Illustration: LEONID A. KULIK PHOTO. SOVFOTO - Infall of meteorite, June 30, 1908, had this effect on a Siberian - forest. See p. 55.] - -The most obvious explanation involves a new and wider concept of matter. -Ordinary terrestrial matter is regarded as composed of atoms having -positively charged nuclei around which negatively charged electrons -revolve. - -Suppose that the situation shown in the first diagram were reversed so -that the nucleus of the atom were negatively charged and the charges of -the particles revolving about it were positive, as in the second -diagram. Matter built up from atoms like those in this diagram would -bear somewhat the same relation to ordinary matter that -2 does to +2. -Such matter is now known variously as _reversed matter_, _anti_-matter, -or, as it was first called by V. Rojansky, _contraterrene_ matter. In -recent years, scientists at the University of California Radiation -Laboratory have produced experimentally all the fundamental particles -necessary for the creation of contraterrene matter. - -What would happen now if a contraterrene meteorite penetrated into the -ordinary matter of the earth? The answer is that just as an electron and -a positron mutually annihilate each other when they collide, so the -meteorite and an equal mass of the earth-target itself would vanish at -the instant of impact. The nearest simple analogy to the actual complex -physical situation is represented by the familiar equation -2 + 2 = 0. - -Unlike “summing to zero” in simple arithmetic, however, the -disappearance of mass, technically called its annihilation, results in a -release of energy, as was long ago observed in the case of -electron-positron annihilation. Where considerable masses are -annihilated, as in an A-bomb explosion, the amount of energy released is -tremendous, as is now well known to everyone. - - [Illustration: A. Representation of the structure of an atom of - ordinary terrestrial matter. The nucleus is positively charged and - around it circle negatively charged electrons. - - B. Representation of the structure of an atom of contraterrene - matter. This is the reverse of the situation in (A). The nucleus - here is negatively charged, and around it revolve positively charged - electrons, also called positrons.] - -The effect of such an energy release as would accompany the infall of a -contraterrene meteorite would be a _natural_ nuclear explosion of vast -power. Such an explosion would account for all the sensational phenomena -observed at the time of the Podkamennaya Tunguska incident; and, -furthermore, would explain why the Russian investigators have never -succeeded in recovering meteorites from this fall. (Further details, p. -102.) - -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. According to an official report of -the Soviet news agency TASS, the investigators obtained “abnormally high -radioactivity readings” which the Russians tentatively considered to be -the result of “a natural nuclear explosion” occurring in the -Podkamennaya Tunguska area on June 30, 1908. - -Science-fiction fans in the U.S.S.R. would like to believe that this -“nuclear explosion” resulted from the impact of a Martian spaceship -rather than a contraterrene meteorite. Reputable Russian scientists, -however, have shown how completely absurd this “fable” of a Martian -landing really is. - -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. - - [Illustration: G. W. RICHEY PHOTO. COURTESY OF YERKES OBSERVATORY - The lunar ray-crater Tycho.] - -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. - -Those who have studied the moon most carefully from an uncomfortable -seat in a cold observatory rather than from a warm, comfortable armchair -are well aware that instead of just one type of lunar crater, there are -really _two_ quite distinct types. No single “explanation” can be -expected to explain satisfactorily lunar features as strikingly -different as: - -First, the rare and distinctive _ray-craters_ described above, which are -scattered at random over the moon, just as the points of impact of -meteorites are upon our own globe. (Roughly defined, a random -distribution is one showing no apparent pattern. For example, if you -were to throw a handful of rice up in the air, the points where the -grains of rice finally came to rest on the floor would be randomly -distributed or very nearly so.) - -Second, the ordinary or “run-of-the-mill” craters sprinkled in profuse -but non-random fashion over the visible face of our satellite. - -The ray-craters on the moon are the counterparts of the meteorite -craters on the earth. This fact is shown not only by their random -distribution, but by the long, bright rays which gave them their name. -On the earth, rays of similar appearance, composed of thrown-out -material, are one of the most characteristic features of explosion -craters, whether the cause of the explosion is the high-speed impact of -a great meteorite or the detonation of a charge of high explosive -(either conventional or nuclear). - -The hypothesis that meteorite craters do exist on the moon is therefore -justified even though it applies to far fewer craters than its -supporters believe. - -As for the ordinary, non-ray lunar craters, these features are not at -all volcanic craters in the usual sense. One of the few good things to -come out of World War II was the first satisfactory explanation of the -“run-of-the-mill” craters on the moon. Jeremi Wasiutynski, a brilliant -Polish scientist forced to take refuge in Norway, sought to explain -these craters as originating in _convection_ processes. - -While the term “convection” may not be familiar, the role convection -plays in filling the sky with beautiful clouds on a hot summer’s day is -well known. Such cloud formation results from convection in the gaseous -free atmosphere. Much more remarkable and regular are the results of -_controlled_ convection in layers of _liquids_ rather than gases. -Laboratory investigation of the effects produced by convection processes -in heated liquids formed the basis for Wasiutynski’s new theory. - -According to this theory, convection processes in the only partially -solidified outer shell of the youthful moon could have given rise to -great numbers of surface features having the size, shape, and -distribution of the common lunar craters. In far more satisfactory -fashion than any other theory so far proposed, the convection-current -hypothesis of Wasiutynski explains the many and distinctive -characteristics of the non-ray craters on the moon. - - - RECOGNIZED METEORITE CRATERS OF THE WORLD - - NAME LOCATION DATE OF - RECOGNITION - - Canyon Diablo Coconino County, Arizona 1905 - Odessa Ector County, Texas 1929 - Henbury McDonnell Ranges, Central 1932 - Australia - Wabar Rub’ al Khali, Arabia 1932 - Campo del Cielo Gran Chaco, Argentina 1933 - [2]Haviland (Brenham) Kiowa County, Kansas 1933 - Mount Darwin Tasmania 1933 - [3]Podkamennaya Tunguska Yeniseisk District, Siberia 1933 - Box Hole Station Plenty River, Central 1937 - Australia - Kaalijarv Oesel, Estonia 1937 - Dalgaranga Western Australia 1938 - Ussuri (Sikhote-Alin) Eastern Siberia 1947 - Wolf Creek Wyndham, Kimberley, 1948 - Western Australia - Aouelloul Adrar, Western Sahara 1952 - - - - - 5. HEAVEN KNOWS WHERE OR WHEN - - -Meteorites have been falling upon our planet for a long time—how long, -it is hard to say with accuracy. Up to now, no specimens certainly -identified as meteorites have been found in ancient rock layers. -Scientists have been able, however, to estimate the age of several -meteorite craters on the basis of the degree of weathering not only of -the crater rims, but also of the meteorites found around the craters. -Age estimates have also been based on the ages of fossils found in -silted-up crater interiors and on other related indirect evidence. - -As we have already noted, the Canyon Diablo, Arizona, crater is thought -to be 20,000 to 70,000 years old. The Odessa, Texas, crater is at least -200,000 years old; and the Haviland (Brenham), Kansas, craters more than -600,000 years old. Clearly, meteorite falls have been occurring over a -very long period of earth history. - -For many years, scientists have studied the distribution of recovered -meteorites around the world in an effort to find out whether there are -any places on the land surface of our globe where meteorites have fallen -in unusually large numbers. - -The idea that any particular spot on the land surface of the earth might -in some way attract more meteorites to it than other locations seems -unreasonable because of the very nature of the target presented by our -planet to the meteorites wandering through space. Not only is the earth -in motion, but it is in very complicated motion. Our earth revolves -about a sun which is also in motion through space. At the same time, the -earth is rotating on its axis. A single point on the surface of the -earth therefore traces a very erratic path in space with the passage of -the years, and the likelihood that this particular point would be struck -by more than one meteorite (if indeed by one!) must be very small. - -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. This extremely high -proportion of falls is undoubtedly due to the fact that for centuries -such an event could hardly have taken place in that country without -attracting the attention of large numbers of people. Apparently, the -majority of Indian meteorites have been recovered as they fell, for only -5 unwitnessed falls are recorded for that country. - -On the other hand, from French West Africa only 5 falls and 3 finds have -been reported throughout an area slightly larger even than India’s. This -country thus provides an example of a sparsely populated region, in many -provinces of which a meteorite fall might pass unobserved, and a fallen -meteorite might remain undiscovered. - -A second factor is the _degree of civilization_ reached by the -inhabitants of a particular area. Those regions of the world which have -been settled the longest and which have seen the development of the -higher cultures will be the most likely to support a populace that will -take an interest in and report the occurrences of natural events like -meteorite falls. Such a populace will also be more likely to bring -suspected meteorites to the attention of experts. - -For example, up to 1953, 55 witnessed falls and 3 unwitnessed falls were -known from France, a country of relatively small area, but with a high -population density and an advanced degree of civilization. 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. Only “human” factors (like population density -and scientific interest in meteorites) can be considered as accounting -for any concentrations of meteorite falls in particular regions or -countries. - -In historic times, the number of man-built structures (houses, barns, -hotels, office buildings, etc.) has increased tremendously. Such -structures have presented an ever-expanding target to hits by falling -meteorites. On pages 73, 74 is a listing of some of the meteorites that -have struck and damaged buildings during the last 150 years or so. The -items included in this list were chosen on the basis of interest, -authenticity, and concreteness of detail. - -The stories of all these meteorite falls are exciting, but none more so, -perhaps, than that of the Beddgelert, North Wales, stone. This meteorite -fell in the small hours of the morning on September 21, 1949. Not many -people saw the fireball that accompanied its descent because of the -early hour (1:45 a.m.), but one of the few persons who happened to be -outside said that it resembled a huge rocket as it flashed across the -sky. He also reported that the appearance of the fireball nearly -frightened the swans in the local park to death, the birds fleeing in -all directions. - -The manager of one of the hotels in Beddgelert simultaneously was -awakened from a sound sleep by the barking of his dog. This was an -unusual occurrence, and the man was surprised by it. While he was trying -to account for the dog’s peculiar behavior, he suddenly realized that -something quite out of the ordinary was happening outside. He heard a -series of unevenly spaced bangs that he later compared to “a naval -broadside.” But as the noise died away and nothing further happened, he -went back to sleep. - -About noon on the next day, the manager’s wife went into the upstairs -lounge of the hotel, a room right under a part of the roof. She was -astonished to find plaster dust all over the floor. It had obviously -come from a jagged hole in the ceiling. And, on the floor, she found an -odd-looking dark stone. - -Investigation showed that this stone had indeed fallen through the roof. -It had made a neat round hole in four overlapping thicknesses of slate, -shattered the underlying lath, made a dent in the lower edge of an -H-section iron girder, and had finally broken through the plaster -ceiling into the hotel’s upstairs lounge. - -Although it was clear that the stone had come through the roof, the -hotel manager did not connect the event in any way with the peculiar -noises he had heard during the preceding night. - -He tried to cut the stone on an emery wheel, but it was too hard. - -That evening, an old miner in the hotel restaurant recognized the stone -as a meteorite. Many years before, he had visited a museum and had seen -specimens of meteorites on display there. - -The slabs of slate penetrated by the meteorite would have provided good -evidence as to the speed of the cosmic missile at the time it struck the -roof. But, unfortunately, these appear to have been thrown away at the -time the roof was repaired. 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. - - [Illustration: G. W. SWINDEL, JR. PHOTO - COURTESY OF ALABAMA MUSEUM OF NATURAL HISTORY - The Sylacauga, Alabama, stone meteorite and the roof (note circle) - through which it plunged and struck a person.] - -Actually, the first _authentic_ case of a person being struck by a -meteorite did not occur until November 30, 1954. Even then, the hit was -an indirect one. At Sylacauga, Alabama, a meteorite fell through the -roof of a house, went through the ceiling of the living room, struck the -top of a radio, and—bouncing in a 6-foot arc—hit the lady of the house, -who was taking a nap on the couch. Fortunately, nearly all of the energy -of the meteorite was spent by the time it struck the woman, and, -moreover, she was covered with two heavy quilts so that she was not -critically injured. But she did receive bruises serious enough to send -her to the hospital. - -The instances just given show that a number of meteorites have struck -buildings and, in one case, a cosmic missile has hit a human being. -Nevertheless, such events are really quite rare. In fact, mathematical -calculations indicate that, on the average, we can expect one meteorite -to fall per township (36 square miles) per 1000 years. A rate like this -does not justify the loss of any sleep over the possibility that you -might some time be hit by a falling meteorite! - - - SELECTED LIST OF METEORITES THAT HAVE STRUCK AND DAMAGED BUILDINGS - - NAME AND LOCATION TYPE APPROXIMATE WEIGHT YEAR - - Baxter, Missouri stone 611 gm.[4] 1916 - Meteorite penetrated roof and struck a log joist, which checked the fall. - The stone lodged in the attic. - Beddgelert, North Wales stone 794 gm. 1949 - Meteorite made a clean hole through 4 thicknesses of slate roof. It then - shattered underlying wood, made tiny dent in bottom edge of H-section iron - girder, and broke through plaster ceiling into hotel lounge below. - Benld, Illinois stone 1770 gm. 1938 - Meteorite penetrated garage roof, top of car, and seat cushion. It struck - and put 1-inch dent in muffler, then bounded back up and became entangled - in seat cushion springs. - Bethlehem, New York stone 11 gm. 1859 - Meteorite struck the side of wagon house, bounded off, hit log upon ground, - bounded again, and rolled into the grass. (A dog lying in the doorway of - the wagon house jumped up, ran out and seized the meteorite, but dropped it - right away, probably because of the warmth and sulfurous odor of the stone.) - Branau, Bohemia iron 19,000 gm. 1847 - Meteorite penetrated into room where 3 children were sleeping and covered - them with plaster and debris. They were unharmed. - Constantia, South Africa stone 999 gm. 1906 - Meteorite penetrated 2 thicknesses of corrugated iron roofing and smashed - ceiling. - Kasamatsu, Japan stone 721 gm. 1938 - Meteorite penetrated roof of house and stopped on floor. It went through - roof tile, ⅓-inch wooden roof-panel, and layer of clay 1 inch thick between - them. - Kilbourn, Wisconsin stone 772 gm. 1911 - Meteorite went through 3 thicknesses of shingles, a 1-inch hemlock roof - board, and a ⅞-inch hemlock floor board. It then glanced in turn against - the side of a manger and the stone foundation of the barn and finally - penetrated 2½ inches into the clay floor of the barn. - Pantar, Philippine Is. stone shower 1938 - Sixteen stones were recovered; thousands “as big as corn and rice grains” - fell on roofs. - Sylacauga, Alabama stone 3863 gm. 1954 - Meteorite penetrated composition roof material, ¾-inch wooden decking, - ¾-inch wooden ceiling, and interior wallboard. It then hit a radio, - punching a 1-inch hole in plywood top, and bounced 90° towards the east, - striking woman lying on couch. - - - - - 6. FINDERS FOOLISH, FINDERS WISE - - -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 different modes of discovery of meteorites not seen to fall are -interesting in themselves. The largest percentage of finds has -unquestionably been made by farmers. The Plymouth, Indiana, meteorite, -for example, was plowed up or, as the farmer nursing the rib bruised by -his bucking plow would probably prefer to say, “plowed into.” So were -such meteorites as the Algoma, Wisconsin; the Bridgewater, North -Carolina; the Carlton, Texas; and the Chesterfield, South Carolina, to -name only a few. A farmer found the Kenton, Kentucky, iron while he was -cleaning out a spring. Another farmer was removing debris from an -abandoned water well in an attempt to revive it when he discovered the -Richland, Texas, iron. A field drainage project brought the Seeläsgen, -Poland, iron to light. A man planting an apple tree near his house dug -out the Mount Joy, Pennsylvania, iron, and a farmer hoeing tobacco -turned up the Scottsville, Kentucky, iron. - -The second largest percentage of finds probably has been made by miners. -Prospectors and placer miners have mistaken numerous iron meteorites for -lumps of silver ore. Among these are the Murfreesboro, Tennessee; Lick -Creek, North Carolina; and Illinois Gulch, Montana, irons. The Aggie -Creek, Alaska, iron was raised by a gold dredge. The gold miners -recognized this meteorite as an unusual “haul” when it announced its -presence by clanging loudly on the metallic screen of the dredge. - -Men at work on road construction are also to be thanked for chancing -upon meteorites of unwitnessed fall, for example, the irons found by -road crews at Bear Lodge, Wyoming, and at Bald Eagle, Pennsylvania. - -Some meteorites have been “found twice.” At Opava, Czechoslovakia, -archeologists discovered seven pieces of meteoritic iron in a buried -Stone Age campsite—the oldest meteorite collection so far on record! -Apparently the paleolithic inhabitants of the Opava region had gathered -the heavy masses together and used them to bolster the fireplaces in -their rude encampment. - -Investigators discovered the Mesaverde, Colorado, iron in the Sun Shrine -on the north side of the Pipe Shrine House, and the Casas Grandes, -Mexico, iron in the middle of a large room of the Montezuma temple -ruins, carefully wrapped in linen cloth like a mummy. Members of an -early archeological survey found the small Anderson Township, Ohio, -meteoritic specimens on altars in mounds of the Little Miami Valley -group of prehistoric earthworks. Some scientists believe that the -American Indians transported these specimens to Ohio from the site of -the Brenham meteorites in Kiowa County, Kansas. - - [Illustration: The Lake Murray, Oklahoma, iron meteorite in place, - just as it was found. See p. 80.] - -Other modes of discovery fall into no pattern and must be regarded as -merely curious. A farmer plowing his field near Pittsburgh, -Pennsylvania, came across a snake. In looking for a suitable stone with -which to kill it, he first seized upon a mass of iron too heavy to lift. -After he had killed the snake with a handy rock, the farmer’s attention -was drawn back to the small but remarkably heavy mass he had first tried -to pick up. He carted it off to the city, where eventually it was -recognized as a meteorite. - -In another unusual recovery, fishermen brought the Lake Okeechobee, -Florida, stone up from the waters of the lake in a net—the only such -recovery recorded in the whole literature of meteoritics, although -three-fourths of all meteorites must necessarily fall into water on our -ocean-covered globe. Again, the members of the Australasian Antarctic -Expedition of 1911-1914 were surprised to find the Adelie Land, -Antarctica, stone lying on the snow some 20 miles west of Cape Denison. - -Because the true nature of meteorite finds has often been -unrecognized—sometimes for many years—these masses have been put to some -rather lowly uses. The finder of the Rafrüti, Switzerland, iron -meteorite used it as a footwarmer, and many of the heavy irons have been -employed as haystack, fence, and barrel-cover weights, or as anvils, -nutcrackers, and doorstops. - - [Illustration: It’s a whopper! See p. 80.] - -Some have fared better, as did the 1,375-pound La Caille, France, -meteorite, which the people of the village used for two centuries as a -seat in front of their church. Others, however, have fared even worse. -Blacksmiths and assayers have smelted up and destroyed a number of iron -meteorites either in the making of tools (like plowshares, axe-heads, -and knife-blades) or in the quest for precious metals. 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. For example, one of the -University of Nebraska men who worked on the excavation and removal of -the large Furnas County stone meteorite (see Chapter 2) became keenly -interested at that time in meteorites in general, and took the trouble -to learn as much as he could about them. Several years later, after he -had become director of a state park museum in southern Oklahoma, a large -metallic mass was reported to him. The finder of this mass of metal had -known of its existence for some 20 years, but had never succeeded in -getting anyone to examine it carefully. The former field worker took one -look at the object and, on the basis of his knowledge of meteorites, -concluded that it probably was a huge iron meteorite. He immediately -called the Institute of Meteoritics by long distance and was able to -give such a wealth of significant details that a field party left at -once for the site. In this way, the Lake Murray, Oklahoma, meteorite was -identified and recovered. - - [Illustration: The Lake Murray core mounted on the meteorite saw - which cut it in half. One of the worn soft iron saw-blades is held - above the meteorite by the saw guides. See pp. 167, 168.] - -The unoxidized central core of this iron weighed more than 600 pounds. -Before excavation this core was surrounded by a “shell” of oxidized -meteoritic material several inches thick, as shown on page 77. Such a -shell of oxide clearly indicated that the meteorite had been subjected -to weathering in the ground for many thousands of years. - -In general, meteorites _seen to fall_—possibly because of the magnitude -and impressiveness of the light and sound effects connected with their -descent—have received respectful treatment after recovery. Most of them -have been presented to men of science for study and eventual display in -some museum collection. Even when kept by their finders, the specimens -usually have been well cared for. After the fall of the Flows, North -Carolina, meteorite in 1849, the owner of the land on which it came down -set the stone in a place of honor on top of a barrel fixed to a post. On -the post he put up the notice: - - “_Gentlemen, sirs—please not to break this rock, which fell from the - skies and weighs 19.5 pounds._” - -This landowner obviously realized that nearly everyone has the -unfortunate urge to hammer on strange rocks. - -Of course, there have been exceptions to the respectful treatment of -meteorites seen to fall. The finder of one fragment of the Zhovtnevy -Hutor, Russia, fall tossed it into the stove, and a farm woman lost -another by throwing it at an unruly horse. A peasant who thought -meteorites possessed miraculous powers powdered up a piece of the -diamond-bearing Novo-Urei, Russia, stone and ate it! - - [Illustration: A polished and etched face of the Lake Murray - meteorite. The length of the cut is a good 23 inches.] - - - - - 7. LANDMARKS, SKYMARKS & DETECTORS - - -The chemist can easily obtain materials for his research work from -reliable supply houses. The meteoriticist (as a scientist who studies -meteors and meteorites is known), is not this lucky. He must search for -the specimens he wishes to investigate wherever they may have landed on -the wide, wide earth. This “needle-in-a-haystack” problem could rarely -be solved if it were not for certain mathematical and instrumental aids -that swing the balance in favor of the meteorite hunter. When meteorites -are seen to fall, these aids can be brought into play only if certain -information is supplied by eyewitnesses of the falls. For this reason, -everyone ought to be acquainted with the facts about meteorite falls -that scientists will need to know in order to make finds, and should -understand how these facts must be reported in order to be of maximum -use to field parties.[5] - -The problem of working out the path a fireball has followed in the sky -boils down to this. The investigating scientists must be able to fix the -position _in space_ of certain important points on the fireball’s path. -This idea of fixing points is not really difficult at all. Suppose, to -take an analogy from baseball, we have base runners on first and third. -These two players are intently watching their team’s clean-up hitter, -who is “crowding the plate.” Consequently their lines of sight intersect -at home plate and give a very good “fix on” its position, as navigators -say. This is the way a fix can be obtained in _two_ dimensions; that is, -essentially, in the plane of the earth’s surface. - - [Illustration: A. A fix determined in two dimensions. The lines of - sight of the runners on first and third intersect at x. - - B. A fix determined in three dimensions. The lines of sight of the - runners on the first and third intersect at x.] - -Now, let us move into the _third_ dimension, since a fireball’s path -through the atmosphere lies in space, not in the “flat” plane of the -earth’s surface. Returning to our baseball diamond, let us suppose that -a helicopter with an enterprising photographer aboard hovers over the -centerfield bleachers so that he can take pictures of the record crowd. -While the umpire is dusting off home plate, the two runners on first and -third simultaneously sneak a look to see what the helicopter is doing. -Their lines of sight now intersect at the helicopter and fix its -position _in space_. - -Similarly, the location of a fireball path in space is determined by the -fixing of certain points on the luminous streak seen in the sky. Instead -of using only two intersecting lines of sight (those of the runners on -first and third in our analogy), scientists investigating a meteorite -fall try to collect as many different lines of sight as possible from -people in the region above which the fireball streaked. The more -commonly determined points are those of the fireball’s appearance and -disappearance and those where “explosions” took place. These points are -generally located by use of the method we have described in some detail -above, the so-called _intersecting-lines-of-sight_ method. - -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? This question has often been twisted around in -newspaper and radio accounts into the meaningless question: In what -direction was the fireball going when you saw it? - -One person cannot give the answer to the second question because from a -single station it is impossible to determine the _true_ direction of -motion of an object seen in the sky. One person can report only an -_apparent_ direction of motion, which is of little or no value in -locating the last point on the luminous path, generally referred to as -the “end-point.” Therefore, though you cannot by yourself determine the -actual direction in which a fireball is _moving_, you can report the -direction in which you were _looking_ when you last saw the fireball, -that is, due south, southwest, northeast, etc. - - [Illustration: O is an observer squinting along the top of a - ping-pong table. A ping-pong ball rolls along the top of the table - from B (beginning) to E (end). To the observer at O, however, the - ball would appear to start at B and end at E if it rolled along any - one of the dashed lines leading from OB to OE. By means of a similar - space-figure, it can be shown that a single observer at O cannot - determine the _true_ direction of motion of a luminous object in the - sky, like a meteor.] - -Scientists are eager to obtain reliable reports on the compass direction -to the fireball’s point of disappearance from as many widely separated -eyewitnesses as possible. They then can plot the individual lines of -sight on a good map, marking exactly where these lines intersect. In -this way, the investigators can make reasonably accurate fixes of the -position of the point on the earth’s surface that is situated directly -below the end-point of the fireball path, as this end-point was seen in -the sky by each pair of eyewitnesses. - -Instead of using the ordinary compass direction to a fireball’s point of -disappearance, you may prefer, as do astronomers, to use the azimuth. -What we have been calling a “compass direction” is one that is expressed -in terms of the cardinal points: north, south, east, west. An azimuth is -a direction stated in _degrees_. Rough azimuths can be taken with a -compass, but for accurate work, a graduated circle, like that on a -transit or theodolite, must be used. Astronomical azimuths begin at the -_south_ point and continue clockwise full circle to 360°. For example, -the lines of sight in the diagram, p. 87, could very well have been -given as astronomical azimuths. And, in the diagram, p. 91, the line of -sight C₁ could have had the precise designation 118° and C₂ that of -222°. - -Every fix serves to guide field parties to areas that are to be -carefully searched for fallen meteorites. Extra-thorough searches are -made if the people living in a particular area reported that they heard -meteorite fragments hissing and whining on their way to earth or heard -the thumps of their impacts on the ground. - -You will notice that so far we have been treating our problem as a -two-dimensional one. We have been working with _directions_ only and -have plotted out direction indicators on a map representing the plane of -the earth’s surface. Now, as we did in our baseball analogy, let us move -into the third dimension. - - [Illustration: Diagram (not drawn to scale) showing plotted compass - directions to the last visible point on a fireball path. (The point - denoted by L in next diagram.) Black dots represent positions of - various observers. Each arrowed line is directed toward the last - visible point as it was estimated by the individual observer. The - oval area, which includes points of intersection of all observed - lines of sight taken in pairs, marks out region in which meteorites - have probably fallen.] - -If, in addition to compass directions to the observed endpoint, -scientists can also obtain the apparent _elevation_, in degrees, of this -point as seen by the various eyewitnesses, then with the help of a -little trigonometry, they can fix the position _in space_ of the -end-point itself rather than the position of its _projection_ on the -surface of the earth. - -This same procedure can be followed in fixing the space-position of any -well-observed point on the fireball path. It therefore becomes possible -when _both_ elevations and compass directions are reported for several -points on the fireball path to determine the flight-path or, as it is -technically called, the _trajectory_, of the falling meteorite through -the atmosphere. Trajectory determinations are of great scientific value. - -You can estimate the compass directions and elevations to the important -points on a meteorite trajectory at the actual time of fall. Or you can -have the scientific field party make or check your measurement at some -later time by setting up a surveying instrument at the very point from -which you saw the fireball. - -The accuracy of your measurements can be improved if you have been able -to “line up” the point, L, at which you saw the fireball disappear, with -some familiar object on the horizon, such as a church steeple, a tall -tree, a telephone pole, or a lightning rod on a farm building. You will -recall that an eleven-year old girl provided one of the field parties -from the Institute of Meteoritics with an excellent observation of the -point of disappearance of the Norton fireball. She was able to do this -because she remembered just where it went out of sight behind a familiar -landmark. - - [Illustration: Method for locating a point on a fireball path. (In - this case the point of disappearance, L.) - - - O₁ First observer. - A₁ Apparent height of point of disappearance (50°). - C₁ Compass direction of point of disappearance (N 62° W). - O₂ Second observer. - A₂ Apparent height of point of disappearance (45°). - C₂ Compass direction of point of disappearance (N 42° E).] - - -If the fall occurs at night, you can help investigators greatly if you -are familiar enough with the brighter stars to use them as “skymarks.” -You simply note as quickly and sharply as you can just where the -fireball path was in reference to those prominent stars. This alert -observation of yours will at least be a great aid to investigators who -are searching for meteorites that may have fallen from the fireball; -and, moreover, there is no telling what else your quick eye might have -captured for science. - -While looking through a window, Kayser, the Polish astronomer, saw a -fireball appear at Rigel and move to Sirius, where it disappeared. This -observation of his proved to be one of the most accurate and -_significant_ ever made of the fall of a meteorite. For it enabled the -German mathematician, Galle, to show that the Pultusk meteorite, which -produced the fireball Kayser saw, came into the Solar System from -interstellar space! - -It is very essential to carefully notice and mark the exact spot from -which your observation was made so that you can return to it if -scientists wish to set up surveying instruments there. - -The map and side view of the Norton County, Kansas, meteorite trajectory -show the practical results that the Institute obtained by use of the -intersecting-lines-of-sight method. The fireball accompanying the Norton -meteorite fall appeared at A. The first “explosion” took place at E₁, -the second at E₂, and the fireball disappeared at L. - -If markers were dropped straight down to earth from each point along the -trajectory or flight-path of a meteorite through the atmosphere, the -line joining the points where the markers fell would be the -_earth-trace_ of this trajectory. The directions of sight to these -various points are indicated for people living in the towns along and -near the earth-trace of the Norton meteorite fall. The solid-line arrows -represent the direction of the point of disappearance; the dotted-line -arrows, the point of appearance; the dash-dot arrows, E₁; and the dashed -arrows, E₂. The probable area of fall is shown as an oval-shaped area, -the longer axis of which is identical with the direction of motion of -the meteorite. - - [Illustration: Path of the Norton meteorite.] - -The many fragments of all sizes recovered from the Norton fall were all -found within the bounds of this oval-shaped area, although unavoidable -errors of observation placed the center of the oval about 4 miles too -far to the north. - -In addition to the questions about direction and elevation, there are a -few more that investigators of meteorite falls would like to have -observers answer. - - At what time (determined as accurately as possible) did the fall - occur? Knowledge of this time is necessary if the path in which the - meteorite was moving about the sun is to be calculated by scientists. - - Did you hear any sounds, either while you were watching the fireball - or after it disappeared? If you heard such sounds as the whining or - hissing of meteorite fragments flying through the air or the heavy - thumps of their impacts on the earth, then you were very close to - where the meteorite came down! - - How many minutes and seconds (again determined as accurately as you - can) passed between the time when you saw the fireball vanish and the - instant when you first heard sounds from it? Such sound data permit - rough determination of the distance from the observer to the point - where the meteorite fell. - - How long did the sounds set up by the meteorite last, and in what - direction did these sounds seem to die out? - -If you or your neighbors find fragments that you suspect are pieces of -the meteorite, these specimens should be shown to the investigating -field parties at once—preferably undisturbed and in the very places -where they fell. In any event, the suspect masses should not be hammered -on and broken up! Even as late as 1958 in a country as science-conscious -as Germany, a beautiful stony meteorite, seen to fall and speedily found -by an alert group of children playing out of doors, was deliberately -broken up into 5 pieces in order that each of the children (aged 9 years -and up) might take home a “souvenir” of the event. Later, these pieces -had to be laboriously reassembled by scientists before any idea could be -gained of the original shape and surface features of the meteorite. - -Even when thorough searches are made, not all the meteorite fragments in -the area of fall may be found for many months. But if the people living -in the region have been alerted and are on the lookout for unusual -specimens or signs of meteoritic impact (such as freshly made holes or -“craters” in the ground, shattered tree limbs, and so forth), the -chances of ultimately finding many or most of the fallen masses are -good. - -As we have already mentioned, numerous fragments of the Norton meteorite -(including one weighing 130 pounds) were found within two to three -months after its fall on February 18, 1948. But the main mass was not -discovered until the following August, when a caterpillar tractor nearly -tipped over into the large impact funnel that this huge stone had made -in the earth. Fortunately, field searchers from the Institute had -already talked to one of the farmers using the tractor and had told him -that just such a “crater” might be found in the very area under -cultivation. Consequently, the crater was promptly reported. - -In surveys concerned with the location and recovery of meteorites _not_ -seen to fall, we find that sometimes meteorite fragments, particularly -the smaller ones, lie on the surface of the ground or at shallow depth. -Such fragments were probably too light to penetrate deep into the ground -or, in the years since their fall, the action of rain, wind, and frost -has uncovered them. - -In such cases, a party of searchers generally spreads out in order to -get over as much ground as possible and each member of the group looks -for meteorite specimens without using instrumental aids. Visual searches -of this type have been very successful, for example, around the Canyon -Diablo crater, where almost the entire plain out to several miles from -the rim once was sprinkled with large and small fragments of meteoritic -nickel-iron. This type of meteorite hunt is of only limited -effectiveness because the specimens (or at least a part of each one) -must be visible to the searchers. - - [Illustration: Collecting small surface specimens of meteorites with - portable detecting devices: a powerful alnico magnet mounted on a - light wooden sled, and a horseshoe magnet at the end of a cane. See - p. 98.] - -To increase recoveries, searchers have employed, in addition to their -eyes, various types of permanent magnets, either mounted on the end of a -cane and used to probe the upper few inches of loose soil, or dragged -behind the searcher on a small, light sled. Meteorite hunters have also -used more powerful portable electromagnets to collect large amounts of -meteoritic material (both solid iron and iron-shale) not only from the -surface but also from shallow depths. Even the best of these simple -magnetic devices, however, are useless in the detection of really deeply -buried meteoritic material. - -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_. - -Although meteorite detectors working on several different principles -have been constructed, we shall limit attention here to the simplest and -most field-worthy design. The essential principle on which it operates -is one familiar to any Boy or Girl Scout who has used a magnetic -compass. The first lesson Scoutmasters teach is not to read compass -directions from such an instrument when it is held near a mass of iron -of considerable size, such as an automobile. 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. - - [Illustration: A 146-pound iron, found by this girl without the use - of instruments although only a small corner of the meteorite was - visible above the surface of the ground.] - - [Illustration: A commercially built meteorite detector in - operation.] - -The operator of such a meteorite detector wears earphones and watches a -signal needle in plain sight on the top panel of the detector. Since the -phone and signal-needle circuits of the meteorite detector are _in -balance_ only when the magnetic field generated by the detector is -undistorted, the disturbing presence of a deeply buried meteorite is at -once revealed by a shrill note sounding in the earphones and -simultaneous motion of the signal needle. If, as in all buried treasure -stories, we use “X” to stand for the spot where the signals from the -detector are strongest, then the meteorite-hunter has only to dig deep -enough at “X” to recover the celestial treasure-trove he is after. - - - - - 8. THE NATURE OF METEORS - - -In answer to an exam question, a freshman astronomy student wrote: - - A _meteor_ is the flash of light - Made by a falling _meteorite_ - As it rushes through the air in flight— - I hope to gosh this answer’s right! - -Doggerel or not, the student’s definition correctly stated the true -distinction between the two terms, and the teacher marked his off-beat -answer correct. - -Defined in more scientific terms, a meteor is the streak of light -(usually of brief duration) that accompanies the flight of a particle of -matter from outer space through our atmosphere. This particle may be as -small as a tiny dust grain or as large as one of the minor planets which -are called asteroids. Fortunately for the inhabitants of the earth, most -of the meteor-forming masses encountered by our globe are of the -“small-fry” variety! - -As the rapidly moving particle plunges earthward through denser and -denser layers of atmosphere, the air molecules offer ever-increasing -resistance to its passage. This resistance heats up the meteorite body -until it glows. Technically speaking, it becomes incandescent. _The -meteor is this incandescence._ We see it as a darting point. Or as a -ball of white, orange, bluish, or reddish light. But the _material -object_ that produced this light is the _meteorite_. The distinction -between these two terms—meteor and meteorite—we must emphasize again and -again because people continue to use them incorrectly, as, for instance, -when they keep saying “meteor crater” instead of “meteorite crater.” - -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. This is a -fact that, for example, one school of modern Russian meteoriticists -overlooked when they were dealing with tiny granules of meteoritic dust -that had been recently found at Podkamennaya Tunguska. These scientists -tried to identify the tiny granules with the meteorite that had fallen -there, June 30, 1908. But the members of the latest (1958) Russian -expedition to that region about the impact point of 1908 clearly -recognize the widespread character of meteoritic dust. 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. - - [Illustration: COURTESY OF UNIVERSITY OF NEW MEXICO PRESS - A bright Giacobinid meteor, photographed from a B-29 during the - shower of October 9, 1946. See p. 115.] - -The term “shooting star,” which is often applied to meteors, in -newspapers and magazine articles, is a misnomer. A meteor is _not_ a -distant sun (that is, a star) in rapid motion, for the whole path of the -meteor lies close at hand within a restricted zone of the earth’s -atmosphere. - -The word “meteor” comes from the Greek word _meteōra_, which once -applied to any natural occurrence _in the atmosphere_—for example, -rainbows, halos, auroras, and so forth. Nowadays, the word “meteor” is -used in a much more specialized sense than it was by the ancient Greeks. -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. - -The region in which meteoric phenomena take place was long the subject -of controversy. Some persons felt that meteors were nearby, like -lightning. Others said that they moved at the distances of the remote -fixed stars. This controversy on the whereabouts of meteors became -heated, although it could have been settled quickly by a simple -experiment you can try out for yourself. - -Hold a pencil against the tip of your nose and look at it first with -your right eye closed and then with your left eye closed. Repeat this -experiment with the pencil held at arm’s length. In the first case, the -pencil will seem to shift position very greatly; in the second, although -the same base line (the distance between your eyes) is used, the pencil -will seem to shift position only slightly. - -Such an apparent shift in position is called a _parallactic -displacement_, or, simply, _parallax_. The notion of parallax is of the -greatest importance in most branches of astronomy, and it leads (with -proper instruments and a little mathematics) to exact determinations of -the distances of remote objects. - -For our purpose, we need not go into all the interesting but complicated -details. Our experiment with the pencil shows that if a meteor was close -by, like a blinding bolt of lightning, then, as seen by a pair of -observers separated by only a few blocks, the meteor would show a large -parallax. But if this meteor was as far away as the stars, it would show -no parallax at all, no matter how widely the pair of observers were -separated on the earth. - -There were many clever scientists among the Greeks, and it is quite -possible that a pair of them actually tried out this simple parallax -experiment on the meteors and so were able to prove that these beautiful -light effects occurred in the high but not too distant layers of the -atmosphere. The earliest calculations of meteor heights that are so far -known, however, were made in Bologna, Italy, in 1719 and 1745—long after -the heyday of Greek science. - -The meteor heights found by the Italians were quite low in the -atmosphere, probably for two reasons. First, the visual (unaided-eye) -observations they had to use were made by eyewitnesses stationed so -close together that accurate fixes were impossible. Secondly, these -visual observations must have related only to the very brightest and -therefore lowest portions of the luminous paths of the meteors through -the atmosphere. - -In 1798, two German students operating from carefully chosen and widely -separated stations began the systematic observation of meteors for -parallax. They found that the height of appearance of most meteors lay -between 48 and 60 miles above the earth’s surface. It is now known that -most meteors, as observed with the naked eye, appear at about 70 miles -and disappear at about 50 miles above the surface of the earth. These -figures, obtained from visual work, still stand in spite of the -development of such modern techniques as photographic and radar -recording of meteor paths. - -Rarely, meteors may appear at heights of 150 or more miles and fireballs -may penetrate to within a few miles of the earth. The average meteors, -however, appear and disappear within a well-defined, high-altitude zone -in the atmosphere. Fortunately, this atmospheric zone serves us as an -effective shield against the constant bombardment of the smaller and -much more numerous particles from outer space. - -In earlier times, scientists thought that the particles becoming visible -as meteors must be tiny dense masses of iron or stone like the material -composing the recovered meteorites. Most modern investigators, however, -believe that the typical meteor-forming particles may be small loosely -bound-together “dust-balls”; that is, fluffy clusters of matter held -together by frozen cosmic vapors, generally referred to simply as -“ices.” In any event, these masses are usually very small, ranging -perhaps from the size of a pinhead to that of a marble. - -Because we cannot collect the tiny masses that are seen only as meteors, -it is impossible to determine their composition by ordinary laboratory -methods. The best we can do is to observe and record carefully the light -these masses give off when they become incandescent in their plunge -through the atmosphere. - -We can examine this meteor light by using the spectroscope and -spectrograph. Through these specially designed instruments we can make -the meteor light reveal the chemical elements present in the -incandescent masses. Each such element sends out light rays as -characteristic of its nature as fingerprints are of the individual who -made them. Photographs taken of these characteristic light rays are -called _spectrograms_, and what might be termed the “fingerprints of -light” recorded on these spectrograms are known as _spectra_—which is -the plural of the word _spectrum_. If the source of light is a meteor, -the photograph shows a meteor spectrum. - -From a study of a considerable number of good quality meteor spectra, -scientists have found that the principal elements in the masses -responsible for meteors are iron, calcium, manganese, magnesium, -chromium, silicon, nickel, aluminum, and sodium. - -As we have already noted, the resistance encountered by meteor-forming -particles as they dash through our atmosphere is so great that they -become incandescent and vaporize. These small bodies must therefore be -in very rapid motion. - -Before we attempt to find out the nature of the paths in space followed -by meteorites, we must take into account the fact that these bodies are -observed from a station—the earth—which is itself in rapid motion. You -may have noticed that on a still day, when rain drops fall vertically -downward, the streaks they leave on the windows of a swiftly moving car -are not vertical but almost horizontal. Obviously, it would be wrong to -say the rain drops are falling from left to right or from right to left -when they are actually falling almost straight down, and it is only the -forward motion of the car that makes them leave horizontal streaks. - - [Illustration: Diagram showing meteorite moving along a “closed” - (elliptic) orbit, e, which intersects the earth’s orbit, E. Held by - the gravitational attraction of the sun, the meteorite is a - permanent member of the Solar System.] - -Similarly, neither the apparent speed nor the apparent direction of -motion of a meteorite with respect to the moving earth is significant. -The important factor is the meteorite’s velocity _with respect to the -sun_ at the time the meteorite is picked up by the earth. - - [Illustration: Diagram showing meteorite moving across the earth’s - orbit, E, along an “open” (hyperbolic) orbit, h. The meteorite is - traveling at such high velocity that it will pass right through the - Solar System and back out into space unless it should chance to - collide with the earth or another planet. The sun, however, in any - case is able to change materially the direction of motion of the - transient visitor to our Solar System.] - -This factor enables us to determine in which of two possible kinds of -path the meteorite was moving _before_ it was “fielded,” as we might say -in baseball, by the earth. This factor tells us whether the meteorite -was moving about the sun in a relatively short, closed, oval-shaped path -or, instead, was following an indefinitely long, open path which began -in the depths of space and would have returned there if the collision -with the earth had not prevented. - -Either type of path is technically called an _orbit_. The closed orbits -are what the mathematicians term _ellipses_; the open orbits, -_hyperbolas_. - -To scientists, the nature of the orbits followed by meteorites is most -important, especially in efforts to determine the mode and place of -origin of these bodies. To rocket engineers and astronauts, it also -matters a good deal whether the meteorites encountered on flights -through space are traveling sedately along closed orbits about the sun -or are zipping swiftly along open orbits. - -The greater the speed of these cosmic “hot-rods,” the more dangerous -they are to space travelers. For example, a mere grain of nickel-iron -moving at 40 miles per second is quite as lethal as a .50-caliber -machine-gun slug, which, relatively speaking, is traveling at only a -snail’s pace. - -As our earth moves along its orbit about the sun, meteoritic bodies can -run into it from any direction. 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. - - [Illustration: Meteor shower. Earth and particle-swarm passing - through the intersection of their orbits at nearly the same moment.] - -In contrast to such a “rear-end” collision, the speed observed would be -far greater if the meteorite happened to collide exactly “head-on” with -the earth. For, in this case, the orbital speed of our planet would be -_added_ to that of the meteorite about the sun. As an example, suppose -that at the earth’s average distance from the center of our Solar -System, the speed of a meteorite with respect to the sun were 32.23 -miles per second. (This speed was actually found for the mass that -produced one of the first meteors photographed simultaneously by the -Harvard stations at Cambridge and Oak Ridge, Massachusetts.) Then if -such a meteorite ran “head-on” into the earth, the speed observed for it -in the atmosphere would be over 51 miles per second. And mathematics -would show that the orbit of this meteorite with respect to the sun was -a wide open hyperbola. - -If the orbit of the earth and the orbit of a swarm of particles of -cosmic matter intersect, and if the earth and the swarm pass through -this intersection in space at nearly the same moment, multitudes of -meteors appear. We then say that a _meteor shower_ takes place. The -position of the point at which the particle-swarm crosses the earth’s -orbit about the sun fixes the date of the meteor shower. - -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. You -may have seen something like this in the case of the sunrise or sunset -effect known as “the sun drawing water.” In this more familiar -phenomenon, the sun’s disk is the area from which shafts of sunlight -radiate out in a beautiful, if somewhat irregular, fan-like pattern. The -area from which the meteors of a given shower seem to come is the -_radiant_ of that shower. - -Meteor showers are named for the constellation in which their radiant -lies. The suffix “-id” (Greek for “daughters of”), or some modification -of this suffix, is added to the name of the constellation from which the -meteors seem to radiate. The Orionid radiant, for example, is in Orion, -the Hunter; the Leonid radiant is in Leo, the Lion; and the Lyrid -radiant is in Lyra, the Harp. Exceptions to this rule do occur, however. -Astronomers may refer to a shower sometimes appearing on the night of -October 9 as the “Giacobinid” shower in honor of the comet -Giacobini-Zinner, which is associated with this particle-swarm. - - [Illustration: Radiant of a meteor shower. Generally not a point but - a small area, here intentionally exaggerated in size. Solid arrows - represent plotted paths of observed meteors. By extending these - paths backwards, observer can determine the radiant.] - -In the course of each year, the earth passes through a number of -particle-swarms of varying densities. Some of the resulting meteor -showers, like the Leonids and Giacobinids, are very feeble in most -years, but sometimes produce spectacular displays. - -The more important recognized meteor showers are: - - NAME OF SHOWER DATE OF MAXIMUM - Quadrantids January 1-3 - Lyrids April 21 - Eta-Aquarids May 4-6 - Perseids August 10-14 - Giacobinids (Nu-Draconids) October 9 - Orionids October 20-23 - Leonids November 16-17 - Geminids December 12-13 - -Certain daytime streams are also known to be active during June and -July. These daytime showers are, of course, invisible in the glare of -sunlight, but they can be picked up by radar devices like those used in -World War II to spot enemy airplanes. - -Some meteor showers have been splendid enough to make a place for -themselves in the historical record. Examples are the Leonid returns of -1833 and 1866, and the Giacobinid showers of 1933 and 1946. During these -displays, meteors fell in a veritable fiery snowstorm, several hundred -meteors sometimes appearing within a minute. - -Not every annual return of a meteor shower is spectacular, however, -since conditions may not be favorable each year for a brilliant display. -After all, both parties to a traffic collision at an intersection must -try to pass through the intersection at the same time. Our earth, like a -well-managed train, always goes through the intersection on schedule, -but the particles responsible for meteor showers are much more erratic. -They may be early or late—or they may not show up at all. Of the meteor -showers seen annually, the Perseids are the most dependable. The Leonids -put on their best shows at intervals of 33 years (1799-1800, 1832-33, -1866, etc.). The Giacobinids at intervals of 6½ years (1933, strong; -1939-40, poor; 1946, magnificent). - -If you plan to observe a meteor shower, here are some suggestions. You -will need: - - Acquaintance with the stars, both faint and bright, in the region - containing the radiant of the shower. - - Comfortable reclining lawn-chair. - - Warm clothing (including blankets) for winter showers or summer ones - at high elevations. - - A patient family that will not only approve of your observing but will - help you get up to watch after midnight, when most showers are at - their best. - - A corner of your back yard (or sun roof) where you can shade your eyes - from street lights and other illumination. - - Timepiece, preferably with radiant dial. - -Sit back and watch Nature put on her show. Any records you make may have -some scientific value even if you note only these two things: Hourly -number of meteors seen. Condition of the sky (clear, hazy, cloudy, etc.) -during each hour of your watch.[6] At present, we know of only one -instance in which it seems probable that a meteorite came to earth -during a meteor shower. The Mazapil, Mexico, iron meteorite fell at 9:00 -p.m. on November 27, 1885, during a return of the now very weak Bielid -meteor shower. Scientists still cannot decide whether or not a mere -coincidence was involved in this case. - -As we have already mentioned, most of the cosmic particles rushing into -our atmosphere evaporate and do not reach the earth at all except as the -tiny congealed droplets and spherules of their own melt. Some cosmic -particles, the _micro-meteorites_, are so tiny that they “stall” rather -than fall down. These minute objects do not melt or disintegrate and so -preserve their original cosmic form unchanged. Scientists have developed -various methods for the collection of both of these types of material in -order that at least rough estimates of their rate of accumulation on the -earth can be made. - -One of the simplest methods of collecting this so-called “meteoritic -dust” is to expose a sticky glycerine-coated glass microscope slide for -at least a 24-hour period in a protected spot well away from locations -where any industrial contamination is in the air. At the end of the -period of exposure, the “catch” on the slide is examined -microscopically, and the individual trapped particles are counted and -classified. Meteoritic dust is also carried down to the ground by rain, -snow, and hail and can therefore be obtained by filtering rainwater or -melted glacier-ice, snow, and hail. - -Such collection efforts have been plagued by the difficulty of -identifying the particles. How can a collector be sure that the dust he -has trapped, even though magnetic and possibly even in part metallic, -does not come from some smelter or other industrial plant? Because of -such uncertainties, the current estimates of the annual deposit of -meteoritic dust for the world range from approximately 20 tons to -several million tons. We need improved collection and identification -techniques if we are to obtain trustworthy figures. - -Recent analyses of rainfall records indicate that the infall of -meteoritic dust produces at least one interesting weather-effect. These -analyses show that rainfall peaks often occur some 30 days after the -appearance of important meteor showers. Apparently, as meteoritic dust -particles from the meteor showers filter down through the cloud systems -in the lower layers of the atmosphere, the individual particles serve as -centers about which atmospheric moisture condenses to form raindrops. -The time lag of approximately a month is considered to be due to the -very slow rate of fall of such tiny particles. It looks very much as if -Mother Nature had beaten man to the idea of “seeding” the clouds to -produce rainfall! - - - - - 9. THE NATURE OF METEORITES - - -So far in this book we have dealt with meteorites indirectly, chiefly in -connection with their fall, distribution, and recovery. In this chapter, -however, we are shifting our attention to the meteorites themselves, and -will tell what the main types of meteorites are, what meteorites are -made of, what they look like, and how to tell them from ordinary rocks. - -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; so you can see that in -meteorites a wide range of composition and appearance is possible. - -All recognized meteorites belong to one of three main divisions,[7] -_irons_, _stones_, and _stony-irons_. - -The irons are composed of an alloy of iron and nickel which may contain -small inclusions of nonmetallic minerals. - - [Illustration: Internal structure revealed when the “etching” - process is applied to that type of meteorite known as a “granular - hexahedrite.” See p. 120.] - -After a cut section of an iron meteorite has been polished, the flat -surface, except for possible inclusions, is mirror-like and resembles -stainless steel. It appears to be remarkably uniform and uninteresting, -but this appearance is misleading. A characteristic and beautiful -structural pattern develops when such a polished nickel-iron surface is -treated with, for example, a special mixture of nitric acid, alcohol, -and Arabol glue. - -This process of treatment is known as “etching.” The different -structural patterns brought out by such etching give us the basis for -classifying the iron meteorites. - -If the etching process reveals certain features from which we can infer -a cubic, or 6-faced, crystalline structure, we classify the iron -meteorite as a _hexahedrite_. - -If etching produces a certain special pattern from which we can infer an -8-faced, or octahedral, crystalline structure, we recognize the second -subdivision of iron meteorites: the _octahedrites_. This remarkable -pattern was discovered and first described by Alois von Widmanstätten, -of Vienna, in 1808. - -The third subdivision of iron meteorites consists of the “structureless” -_ataxites_. (From the Greek for “without arrangement.”) On an ataxite, -etching brings out only a finely granular pattern with a stippled -appearance. - -The _stones_ are composed chiefly of minerals that are combinations of -various elements with silicon and oxygen—for example, olivine (Mg, -Fe)₂SiO₄. Meteorites belonging to this division also contain -combinations of elements with oxygen—such as magnesium oxide (MgO) and -aluminum oxide (Al₂O₃). Usually, the stony groundmass contains scattered -specks, grains, and thin veins of the same shiny nickel-iron alloy that -makes up the iron meteorites almost in their entirety. - - [Illustration: A. BREZINA & E. COHEN PHOTO - Widmanstätten pattern which emerges when the carefully polished - surface of that type of iron meteorite technically known as a “fine - octahedrite” is “etched.”] - -The _stony-irons_, as the name indicates, are an “in-between” division. -Some of the stony-irons, called _pallasites_, are sponge-like but rigid -networks of nickel-iron alloy in which the smoothly rounded openings in -the sponge enclose small gemlike masses of olivine. A cut and polished -section of a pallasite showing round and oval gems of yellow-green -olivine set in a silvery mesh of nickel-iron is a beautiful museum -specimen indeed! - -In the _silicate-siderites_, another type of stony-iron, a nickel-iron -matrix is studded with angular fragments, shreds, and splinters of -silicate minerals of all sizes. In the photograph, we can see that each -of the various areas of the nickel-iron matrix (lighter in color) -exhibits its own distinct crystallographic orientation, as is clearly -indicated by the different Widmanstätten patterns. - -Even a hasty comparison of polished sections of silicate-siderites and -pallasites will leave no doubt that two quite distinct modes of -formation were required to produce stony-irons of such different types. - -Meteoritic nickel-iron has the following average chemical composition. -To the nearest tenth, this alloy contains: Iron (Fe), 90.9%; nickel -(Ni), 8.5%; cobalt (Co), 0.6%. This alloy gave scientists the key to the -development of commercial stainless steels. It may also contain small -amounts of phosphorous, sulfur, copper, chromium, and carbon. - -The average chemical composition of stony meteoritic material is -somewhat more complicated. To the nearest tenth, the “stones” contain: -oxygen (O), 41.0%; silicon (Si), 21.0%; iron (Fe), 15.5%; magnesium -(Mg), 14.3%; aluminum (Al), 1.6%; calcium (Ca), 1.8%; sulfur (S), 1.8%. -The stony material may also contain smaller percentages of nickel, -cobalt, copper, carbon, chromium, and titanium. - - [Illustration: A. BREZINA & E. COHEN PHOTO - Enlarged section of a stony-iron meteorite showing rounded olivine - grains (dark in color) set in a network of nickel-iron alloy (light - in color).] - - [Illustration: A. BREZINA & E. COHEN PHOTO - Polished and etched section of a silicate-siderite showing angular - fragments of silicate minerals (dark in color) imbedded in a - metallic matrix.] - -In the stony-iron meteorites, we analyze the nickel-iron and stony -portions separately. On the average, each of these portions has about -the chemical composition that is given for it above. - -Mineralogists have identified a variety of familiar minerals in -meteorites. These include olivine, the plagioclase feldspars, magnetite, -quartz, chromite, and, rarely, microscopic diamonds. All of these -minerals are found here on earth in such igneous rocks as basalts and -peridotites. - -On the other hand, the meteoritic nickel-iron alloys (kamacite, taenite, -and plessite, for example) and such meteoritic minerals as schreibersite -(nickel-iron phosphide) and daubreelite (iron chromium sulfide) do _not_ -occur naturally on the earth. - -We should stress here that although unusual _combinations_ of known -elements are present in meteorites, no new _elements_ have been -discovered during the increasingly intensive study of these masses -during the last 150 years. - -The majority of stony meteorites show a structure not found in -terrestrial rocks. These meteorites are made up of rounded, shot-like -bodies called _chondrules_ (from the Greek word for “grain”). The -individual chondrules may vary in size from those as large or even -larger than a walnut down to dust-sized grains. The most common size is -about that of peppercorns. The chondrules are often composed of the same -material as the groundmass in which they are imbedded and unless the -meteorite containing them is a very fragile one, they will break with -the rest of the mass, as will sand grains in a quartzite. If the -meteorite is fragile, however, the individual chondrules can generally -be broken out whole. Meteorites containing chondrules are called -_chondrites_. - - [Illustration: COURTESY OF AMERICAN MUSEUM OF NATURAL HISTORY - Microphotograph of a thin section of a chondrite, showing the - circular, or nearly circular, cross sections of a number of - chondrules, including one of large size at the upper edge of the - section.] - -A small percentage of stony meteorites have no chondrules. These -meteorites are known as _achondrites_ (meaning “not chondrites”) and -they resemble terrestrial rocks more closely than the chondrites do. -Some achondrites contain almost no trace whatever of metal, although in -others (for example, the Norton County meteorite, of Chapter 2) small -lumps and specks of nickel-iron are sparsely distributed through the -stony groundmass. - -Meteorites are as variable in shape as they are in composition and -structure. Many are cone-shaped; others shield-, bell-, or ring-shaped; -still others pear-shaped. One iron fragment recently recovered from the -Glorieta, New Mexico, fall has been described as “macro-spicular,” -meaning needle-shaped on a very large scale. The photographs opposite -illustrate a number of the commoner forms known. The Glorieta specimen -has been nicknamed “Alley Oop’s shillelagh,” for only a person of great -strength could wield this 13-pounder with ease! - -In general, the shape of meteorites depends upon the amount of mass lost -by “evaporation” during passage through the earth’s atmosphere. This -factor, in turn, depends not only upon the speed of transit, but also on -such physical characteristics of the meteorite as its tensile strength -and whether or not it contains certain alloys and minerals that vaporize -more easily than the rest of the meteorite. The ring-shape of the -Tucson, Arizona, iron is believed to have resulted from the “melting -away” of a huge inclusion of stony material during the descent of the -meteorite. - - [Illustration: CHICAGO MUSEUM OF NATURAL HISTORY PHOTOS - (BOTTOM RIGHT) INSTITUTE OF METEORITICS PHOTO - A few of the many shapes exhibited by meteorites: ring-shaped, - perforated and highly irregular, pear-shaped, jaw shaped, - needle-shaped.] - -When meteorites are recovered and taken to the laboratory for study, one -of the first things scientists do is to weigh them. If a meteorite is -very large, special scales sometimes have to be constructed for this -purpose. Such was the case for the largest meteorite so far weighed: the -giant Ahnighito, Greenland, meteorite, which Peary brought to New York -City by ship. (See Chapter 3.) A specially constructed scale on which -this huge mass is now mounted gives for its weight about 68,000 pounds. -Other meteorites famous for their great size are: the Bacubirito, -Mexico, 27 tons; Willamette, Oregon, 14 tons; Morito, Mexico, 11 tons; -and the Bendego, Brazil, 5 tons. All of these are irons. - -The largest stone meteorite so far recovered as one mass is the -so-called Furnas County, Nebraska, stone, which is the principal -fragment of the Norton, Kansas, fall, and weighs about 2,360 pounds. - -At the other end of the size-range, investigators have recovered -meteoritic masses weighing no more than a small fraction of a gram. From -a stone shower that occurred at Holbrook, Arizona, field searchers have -found some of the very smallest specimens in anthills. The insects had -carried these tiny meteorites along with sand and garnet grains in -building their hills! - - [Illustration: COURTESY OF AMERICAN MUSEUM OF NATURAL HISTORY - The Willamette iron, famous for its great size and weight (14 - tons), on exhibit at the Hayden Planetarium, New York City. See pp. - 36, 39.] - -The only sure way to determine whether or not an object _is_ a meteorite -is to have a small piece of it (say, a fragment the size of an egg) -tested chemically and microscopically by an expert on meteorites. -Nevertheless, there are several questions whose answers will help you to -decide whether or not you are on the right track in suspecting that a -“rock” you have found may be a meteorite: - - Is your specimen especially heavy? - - Does your specimen show a thin blackish or brownish crust on its outer - surface? - - Does your “rock” have shallow, oval pits on its outer surface? - - If the specimen has a corner knocked off, do you see specks and grains - of metal on the broken surface? - -Is your specimen especially heavy? 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. To -illustrate how this crust forms, consider a snowball that you bravely -hold in your freezing hand until the outer surface melts. If you then -were to leave the snowball outside overnight, the melted outer surface -would freeze into a hard crust. - - [Illustration: Piezoglyphs (oval pits resembling thumb-prints) in a - stone meteorite, found at Belly River, Canada. See p. 132.] - -In similar fashion, the surface of a meteorite melts during the -blazing-hot part of its flight through the air, only to “freeze” into a -hard, firm coating in the lower, cooler portions of its path. This -hardened coating, the fusion crust, is of much importance. Its presence -is one of the best indications that a “rock” is really a meteorite. From -the character of the fusion crust, experts can piece together a good -deal about what happened to a meteorite on its way down to earth. If you -should be lucky enough to find a meteorite, don’t break off the fusion -crust. A whole encrusted specimen in the hand is worth 200 crustless -fragments scattered at your feet! - -Does your “rock” have shallow, oval pits or depressions on its outer -surface? Such features are known technically as _piezoglyphs_ (Greek -_piezein_, to press + _glyph_, to carve) and popularly as -“thumb-prints.” They were formed during the meteorite’s flight through -the atmosphere when the softer portions of its outer shell were “eroded” -away, leaving small scooped-out places. These pittings are very similar -to the prints that would be made by the human hand in a lump of modeling -clay or bread dough. In one case, they gave rise to the false idea that -the meteorite had fallen in a plastic state and that the imprints had -been formed when its finders first pulled the mass out of the ground by -hand. - -If the specimen you have found already has a corner knocked off, do you -see specks and grains of metal on the broken surface? Such scattered -bits of nickel-iron (not to be confused with the shiny mica flakes often -seen in igneous rocks) characteristically occur in the grayish or -brownish groundmass of stony meteorites. If your specimen is unbroken, -hold it lightly against a spinning carborundum wheel or use a file to -grind a small flat surface upon it, and then examine this surface for -specks of metal. - -If the answers to these questions are yes, then there is a good -possibility that you have found a genuine meteorite. - -If meteorites remain buried in the ground for a long period of time, -their characteristic surface-features may weather away. Under such -conditions, iron meteorites develop heavy-layered coatings of rust (iron -oxide) as much as several inches in thickness. If irons stay in the -ground long enough, they may rust away almost completely and turn into -shale balls, like those found near the ancient Wolf Creek, Australia -meteorite crater. (See Chapter 4.) Stone meteorites buried in the ground -for any great length of time may disintegrate and become completely -unrecognizable as meteorites. - -The fact that meteorites of all kinds are attacked by weathering has -always argued strongly in favor of their prompt recovery. In the case of -witnessed falls, prompt recovery is even more important, for only thus -can specimens still retaining measurable amounts of various short-lived -radioactivities be made available to physicists eager to investigate -them with the most modern radiometric equipment. - - - - - 10. TEKTITES, IMPACTITES & “FOSSIL” METEORITES - - -Before southern Australia was occupied by the white man, the native -tribesmen of that region treasured certain small rounded pieces of black -glass as medicine stones, rainmaking stones, and message stones. The -Wadikali tribe referred to these objects as _mindjimindjilpara_, a word -meaning “eyes that look at you like a man staring hard.” The early -European settlers of the area called the same black glassy masses -“blackfellows’ buttons.” Both phrases applied to objects that modern -scientists call “australites,” which are now one of the best known types -of _tektites_ (Greek: _tēktos_, molten). - -These Australian tektites and the tektites from many other countries -around the world are a problem to meteoriticists. The question is, are -they really meteorites? Many investigators believe that the answer is -yes, and they are inclined to add to the three main divisions of true -meteorites listed in the preceding chapter, a fourth: the tektites. - -These mysterious glassy objects occur in such widely separated -localities as Czechoslovakia, the Philippine Islands, Borneo, the Ivory -Coast of Africa, Australia, Indo-China, Texas, Malaya, and Java. In -these and still other areas, they have been found by the thousands in -surface deposits of sand, clay, and gravel. - - [Illustration: (left) “Flanged buttons” from Australia. (right) - Several sizes of “dumbbells” from Australia. See p. 136.] - -Tektites have never been seen to fall. In spite of this fact, as we -noted above, a number of scientists believe that, like the meteorites, -the tektites really did come from outer space but, that they fell to -earth before man was here to see them come down—or at least before he -had acquired the means and skill to make lasting records of such an -occurrence. - -Tektites are usually quite small, weighing between 1 and 100 grams, -although a few of much larger size have been found. One large specimen -from the Philippines weighed about ½ pound. Two giant tektites, one -weighing ¾ pound and the other over 1 pound, are in the collection of -the British Museum. In composition, tektites are an impure silica-glass -containing low percentages of the oxides of such elements as iron, -magnesium, calcium, and titanium. - -If tektite fragments are held under a lamp and observed by reflected -light, their thicker parts generally appear to be jet-black. If, -however, these same specimens are held up _between_ the observer and the -light, then their thin razor-sharp edges are seen to be bottle-green, -yellow-green, brownish, or even colorless. - -In shape, many tektites are roundish or oval. Others are shaped like -dumbbells, ladles, canoes, and teardrops. So they are known by those -descriptive terms. One particularly interesting example is the unusual -“flanged button” of Australia. Tektites of this type look like miniature -South American gold-pans, the _bateas_, heaped high with pay dirt. -Australian gold-field workers regarded these tektites as magical, and -used them as good-luck charms. Superstitious American gold-seekers -brought them into the United States all the way from Australia! - - [Illustration: (above) Rounded tektite from Texas. (below) Deeply - grooved bediasite from Texas.] - -Some tektites (for example, many of the “bediasites” from Texas) are -deeply grooved and channeled, and have a very jagged and irregular -appearance. Even the smoother tektite surfaces are characterized by flow -lines, flow ridges, and bubble pits. - -Many weathered pebbles and fragments of obsidian somewhat resemble the -tektites superficially. There is a very simple test by which you can -distinguish true tektites from obsidian. If you hold a thin splinter of -tektite glass in a blowpipe flame, the glass melts quietly but only with -the greatest difficulty. On the contrary, when you test in the same -flame the terrestrial glass, obsidian, it froths up much more easily, -into a bubbly, whitish mass. - -Although the question of where the tektites came from is still not -entirely settled, most scientists agree that all tektites did have a -_common_ origin. For example, tektites from widely scattered localities -on the earth’s surface show not only similar queer shapes and surface -markings (technically known as “sculpturing”), but also have very much -the same chemical composition and, in particular, the same content of -radioactive elements. - -Because the tektites chemically resemble certain terrestrial rocks, -scientists at first believed that some kind of earth process must have -created them. One suggestion was that lightning had fused dust particles -suspended in the air to form them; another, that they had come from -volcanoes; still another, that the tektites were simply inclusions that -had weathered out of terrestrial rocks. A few scientists once took -seriously the possibility that tektites were refuse from primitive glass -factories! - - [Illustration: Tektite vs. obsidian, after blowpipe test.] - -While such theories have not yet been completely discarded, most -scientists now feel that the tektites had their origin somewhere outside -the earth. There are several reasons for this belief. First, the shape -of such unusually symmetrical forms as are found, for example, among the -australites, indicates that these small bodies at one time were members -of a swarm of freely-spinning liquid masses. Again, flow features -observed on the surfaces of certain tektites (and the fusion crust -definitely identified on one specimen) show that these bodies at some -time must have traveled through the earth’s atmosphere at high velocity. - -If, then, the tektites were not produced by earth processes, where did -they come from? According to primitive legends, they were “rocks” or -“pebbles” from the moon. Indeed, one of the earliest scientific theories -as to their origin (proposed by the Dutch authority Verbeek in 1897) -likewise attributes them to debris jetted out from the moon. Another -holds that tektites are fragments of the outermost glassy layers of some -so-called “meteorite-planet,” or planets.[8] Still another idea is that -tektites are what is left of a comet when it passes so close to the -blazing-hot sun that the “ices” which make up most of the cometary -nucleus (head) are all distilled away. - -These theories of the origin of the tektites are based primarily on -their observed shapes, surface features, and compositions. The senior -author of this book has suggested still another possible theory based on -the very unusual nature of the observed distribution of the tektites on -the face of the earth. - -To explain this theory, we first recall that the planet on which we live -is more nearly a true sphere than are such familiar “spherical” objects -as baseballs or basketballs. Consequently, any plane through the center -of the earth cuts its surface in a curve that to all intents and -purposes is what geometers refer to as a _great circle_. - - [Illustration: Every plane passing through the center of a sphere - intersects the surface in a great circle. In this figure, only the - front half of the great circle cut out by the plane is shown.] - -Now the significant fact is that all the tektite deposits known at -present are located on or very near to three great circles on the -earth’s surface. Mathematics shows that if some earth process had -created the tektites at random over the surface of the earth, then the -odds would be very strongly against the existence of this peculiar -“great-circle distribution.” But such distribution along great circles -would be _expected_ if the tektites had resulted from what might be -likened to “chain-falls” upon the earth of objects like nearby -satellites moving in orbits encircling our globe. - -This notion brings up the interesting possibility that at some time in -the remote past, the earth may have been the proud possessor of a set of -equatorial rings. These rings would have been similar to those at -present circling in the plane of Saturn’s equator. (Jupiter, too, may -once have had its own set of equatorial rings.) The rings of Saturn are -known to be made up of countless very small meteorites. In the same way, -the “earth rings” of prehistory could have consisted of swarms of tiny -nearby meteoritic satellites—the tektites—moving about the earth in the -plane of its then-existing equator. - -Eventually, the innermost of these small natural satellites collapsed -onto the earth’s surface, falling along the old equator. At least twice -thereafter, this process was repeated, the points of impact of the later -tektite falls again lining up along whatever great circle of the earth -happened to be the equator at the time of fall. - -As the geologists and other investigators have shown, major shifts have -occurred in the position of the earth’s equator during past geologic -ages. This fact is well-substantiated by discoveries of fossil shells -and plants on the cold Antarctic continent and of glacial deposits in -hot South Africa. Therefore, we could hardly expect the tektite -deposits, which are believed to have fallen at widely separated -intervals of time, to have all occurred along a _single_ great circle on -the earth’s surface. - -As you can see, the so-called “tektite-puzzle” is a complex one. As if -this were not bad enough, Mother Nature has added to the confusion by -creating in addition to the tektites another type of silica-glass not -only found along the very same three great circles sprinkled with true -tektites, but also having other features in common with the tektite -glasses. - -At Mount Darwin in Tasmania and at Wabar in the Rub’ al Khali desert of -Arabia, large and small fragments of this curious silica-glass have been -collected. At Wabar the masses of silica-glass were found in and about -the rims of a series of meteorite craters formed in nearly pure sand, as -we pointed out in Chapter 4. These meteorite craters are known to have -resulted from the high-speed impact of iron meteorites upon the sand -dunes of the Wabar site. Since the silica-glasses of Wabar have been -found to contain countless spherules of nickel-iron of the same -composition as the iron meteorites discovered about the Wabar meteorite -craters, it seems quite certain that both the sand of the earth target -and the nickel-iron of the falling meteorites were vaporized by the -intense heat generated at impact. Consequently, it is natural that these -Wabar masses of congealed silica-glass and nickel-iron be called -_impactites_. They are silica-glasses, created chiefly from -_terrestrial_ materials by the impact of large crater-forming -meteorites. This same name is now applied to all silica-glasses believed -to have the same origin as those at Wabar. - -As regards size if not composition, the crater-forming meteorites -responsible for the Wabar and other impactites may have been big -brothers of the small-fry responsible for the showers of true tektites. -Or these big ones may have moved about the earth in orbits distinct from -those followed by the tektite swarms but lying in the same plane as one -of these swarms. - -In addition to the curious puzzle of the tektites, meteoriticists have -also run up against the problem of “fossil” meteorites or, more exactly, -the problem of the _lack_ of “fossil” meteorites. As we have already -mentioned, no positively identified meteorite has ever been found in -other than the most recent rock layers. With all the mining—particularly -coal mining—that has gone on throughout the world in historic times, -this fact does seem astonishing. - -A number of explanations can be suggested for this absence of ancient -meteorites. In the geologic past, meteorite falls may not have occurred -as often as they do today. For example, the primeval atmosphere of the -earth may have been so much denser than at present that even quite large -meteorites were totally vaporized as they passed through it and -therefore never reached the ground. Again, even if the rate of infall of -meteorites was the same in the remote past as now, still various -weathering processes active ever since the earliest meteorites fell may -have so changed them in appearance and composition that they are no -longer recognizable for what they are. - -Several unusual lumps of rock from England and a mass of iron from -Austria, all found at some depth by coal miners, have been tentatively -put forward as “fossil” meteorites. But studies of these masses have so -far produced no conclusive results. Still, we should not ignore the -possibility that someday meteorites may be found and identified in rocks -of considerable age. - - [Illustration: L. J. SPENCER PHOTO - COURTESY OF AMERICAN MUSEUM OF NATURAL HISTORY - Mysterious glass objects found in the Libyan Desert. (right) Cut - and polished specimens.] - -Does it seem as if we have posed more problems than we have solved in -this chapter? It is very true that we have done just that. In speaking -briefly about the tektites, the impactites, and the absence of “fossil” -meteorites, we have by no means tried to present the last word on the -troublesome but highly interesting problems connected with these -objects—problems that admittedly may take scientists years or even -decades of further research to solve. Perhaps you will find here the -kind of unusual and thought-provoking problems that make the study of -meteorites a rather special challenge. If so, you may wish to take an -active part someday in unraveling these puzzles. - - - - - 11. OMENS AND FANTASIES - - -Men seem to have always taken an interest in meteorites, but not until -the early nineteenth century were these objects considered to be worth -preserving for _scientific_ study. - -In the beginning, people believed that because meteorites fell from the -heavens, they were either gods themselves or messengers from the gods. -The more civilized of early men therefore carefully kept the fallen -meteorites. They draped them in costly linens and anointed them with -oil. In many instances, the people built special temples in which -meteorites were actually worshipped. Some of the holy stones of the -ancients, such as the Diana of the Ephesians, mentioned in the Bible as -“the image which fell down from Jupiter,”[9] are now thought to have -been meteorites. - -Meteorite worship was common long ago in the Mediterranean area and in -Africa, India, Japan, and Mexico. This practice still persists in some -regions even in modern times. The Black Stone of the Kaaba, for example, -has been sacred to all Mohammedans from about 700 A.D. right up to the -present. It is said to be a meteorite although this fact has never been -verified, because strict religious taboos connected with the stone -prevent any scientific examination or study of it. On the contrary, the -Andhâra, India, meteorite is known to be a genuine one. The story of the -fall and preservation of this meteorite provides a fairly modern example -of practices rooted in the ritual and custom of far more ancient times. - -At about 4:00 in the afternoon of December 2, 1880, the people of -Andhâra heard a noise like that made by a gun. Some of the villagers saw -a “dark ball” come to earth in a field near them. This falling object -sent up a small cloud of dust as it struck the ground. After the stone -had been recovered from the field and the dust had been washed from its -surface, two Brahmin priests took charge of it and began to collect -money for the erection of a temple in which the holy object could be -properly displayed. - -The scientist who promptly investigated the Andhâra fall reported that -throngs of worshippers were crowding into the as yet unfinished brick -temple to make offerings of flowers, sweetmeats, milk, rice, water, bel -leaves, and of course money. The stone had been named Adbhuta-Nâth, “the -miraculous god.” It was shaped like a round loaf of blackish bread and -weighed an estimated 6 pounds. The scientist was not allowed to touch -it, but he got close enough to verify that the stone was a meteorite -covered with a typical blackish fusion crust. - -Not only has man worshipped meteorites, but during a period extending -from approximately 300 B.C. to 300 A.D., emperors and self-governing -cities frequently marked the fall of meteorites by minting special coins -or medals known as _betyls_.[10] One of these is the betyl of Emisa, -Syria, made by Antonius Pius (138-161 A.D.). The historian, Herodotus, -accurately described the object honored by this betyl as: “A large -stone, which on the lower side is round, and above runs gradually to a -point. It has nearly the form of a cone, and is of a black color. -_People say of it in earnest that it fell from Heaven._” The stone is -shown on the coin as carried on a quadriga (a carriage drawn by four -horses) under a canopy of four sunshades. - - [Illustration: COURTESY OF AMERICAN MUSEUM OF NATURAL HISTORY - Drawing of multiple fireball, over Athens, October 18, 1863. J. F. - J. Schmidt, the celebrated pioneer fireball observer, described it - as a mass of dazzling light “bringing into view land and sea, with - the Acropolis and the Parthenon a mile away across the city.”] - -Many ancient peoples held meteorites in great reverence, particularly if -they were seen to fall. But at the same time, other more -practical-minded individuals made good use of the durable and easily -worked alloy provided by nature in the nickel-iron meteorites. This -alloy was frequently used to make ax-heads, spear and harpoon points, -knives, farming tools, stirrups and spurs, and even pots and other -utensils. Archeologists have found earrings and similar ornaments -overlaid with thin sheets of hammered meteoritic iron in Indian mounds -of the Ohio Valley. They have also discovered round beads made of -nickel-iron in Indian mounds of the Havana, Illinois, area and in the -still more ancient Egyptian ruins at Gerzah. - -Meteoritic iron has often been used in the manufacture of special -swords, daggers, and knives for members of the royalty. Atilla and other -early conquerors of Europe boasted of “swords from heaven.” Emperor -Jehangir (1605-1627) ordered two sword blades, a knife, and a dagger to -be smelted from the Jalandhar, India, meteorite, which fell on April 10, -1621. In the early nineteenth century, a sword was manufactured from a -portion of the Cape of Good Hope meteorite for presentation to -Alexander, the Emperor of Russia. Even as late as the end of the -nineteenth century, several swords were made from a part of the -Shirihagi, Japan, iron meteorite at the command of a member of the -Japanese court. - - [Illustration: A Russian artist’s pen-and-ink drawing of an - extremely brilliant detonating fire ball or bolide. See page 102.] - -In the Europe of the Middle Ages, meteorite falls and meteor showers, as -well as other “unnatural” events like comets, eclipses, and displays of -the aurora borealis, were regarded with superstitious awe by commoner -and king alike. The medieval mind always sought to interpret events -connected in any way with the heavens as somehow influencing the affairs -of men. A bishop explained that the great meteor shower of April 4, -1095, forecast “the changes and wanderings of nations from kingdom to -kingdom.” The fact, however, that the First Crusade began within a year, -is mere coincidence. - -In referring to celestial events, Shakespeare often expressed the view -that was common in the Middle Ages and the Renaissance. An example is: - - The bay-trees in our country are all wither’d - And meteors fright the fixed stars of heaven; - The pale-faced moon looks bloody on the earth - And lean-look’d prophets whisper fearful change, - . . . . . . - These signs forerun the death or fall of kings. - (_Richard II_, II, iv, 8-11, 15) - -Yet the descent of meteorites from the heavens was not always regarded -as a forewarning of bad fortune. On November 16, 1492, a 279-pound -meteorite fell at Ensisheim in Alsace, not far from the battle line -separating the armies of France and the Holy Roman Empire. Emperor -Maximilian, the leader of the Empire’s forces, commanded that the fallen -stone be carried to his castle. There a formal war-council was held to -determine what the strange event could mean. - - [Illustration: COURTESY OF AMERICAN MUSEUM OF NATURAL HISTORY - Drawing of Andromedid meteor shower, November 27, 1872.] - -The Emperor and his councillors decided that the fall of the meteorite -at such a time and place was an omen of divine favor which meant good -fortune to the cause of the Holy Roman Empire. After breaking off two -small pieces of the stone, one for the Duke of Austria and one for -himself, the Emperor forbade further damage to it. He also gave orders -that the stone be hung in the parish church in Ensisheim for all to see. -In this way, the Ensisheim stone became the very first meteorite of -witnessed fall to be preserved down to the present day—and all because -of the superstition of a famous military leader. - -The discussion to this point makes clear that in ancient, medieval, and -Renaissance times, meteorite falls were considered as startling and -disturbing events, which frequently were interpreted in strange and -mistaken ways. But the fact that meteorites actually did fall from the -heavens was not questioned. As the so-called “Age of Reason” opened, a -curious change in attitude toward meteorite falls took place. - -At the very time that knowledge in general increased, men of learning -began to deny that meteorite falls occurred at all! The scientists of -the French Academy, in particular, were very positive on this point. -Since the era was one in which all Europe sneezed if “la belle France” -had a cold in the head, it was a trying time not only for the early -meteoriticists, but for all who had the nerve to insist they had seen -rocks fall from the sky. - -By the end of the 1700’s, the authorities had studied the evidence -relating to meteorite falls and had completely rejected it. They said -that there was no “proof” whatever that “stones fell from the heavens.” -These early scientists openly sneered at people who claimed that they -had seen meteorites fall. It was felt that the spectators of such events -either had merely been “seeing things,” or had surely been reporting -light and sound effects connected with nothing but ordinary -thunderstorms. - -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. - -In 1794, Chladni published an extremely important paper concerning a -large spongelike mass of “native iron” found near Krasnoyarsk, Russia. -This object had been discovered in 1749 by a Russian blacksmith, and it -was studied in 1772 by P. S. Pallas, an early traveler. Chladni -concluded that the mass of iron[11] must have fallen from the heavens, -because it had been “fused” (but not by man, electricity, or fire) and -also because there were no volcanoes anywhere around its place of find. - -Chladni supported his theory by listing numerous reports of meteorite -falls dating from ancient and medieval times. But Chladni’s fellow -scientists flatly rejected his theory as clever but not satisfactory. - -With the fall of the Siena meteorites in Italy on June 16, 1794, the -controversy regarding the possibility that stones actually fell from the -sky became particularly heated, and remained so for nearly ten years. -During this interval, two other important meteorite falls occurred: Wold -Cottage, England, on December 13, 1795, and Benares, India, on December -19, 1798. Scientists had a hard time finding explanations for these -well-observed events, and some of the theories put forward to account -for them far outdid Chladni’s in “cleverness,” if that be the correct -word. - -One scholar, writing in 1796, suggested that the masses which fell at -Siena resulted from the solidification at great height of volcanic ashes -from Mount Vesuvius. These ashes had supposedly been carried northward -beyond Siena and then been “brought back by a northerly wind, congealing -from the air....” - -Fortunately, in 1803 Edward Howard’s chemical work on meteorites came to -a successful conclusion. This patient chemist made analyses of samples -from the Siena, Wold Cottage, and Benares falls and from an older -Bohemian fall. He also had the samples studied mineralogically by a -fellow scientist. From the results of these investigations, he drew the -following conclusions, which admirably supported Chladni’s well-reasoned -and thoroughly documented theory regarding meteorite falls: - - All four of the stones studied had very nearly the same composition. - - Despite the fact that the stones contained no new elements, their - mineralogical character differed in several important respects from - that of any rocks found naturally on the earth. - - The four masses must have had a common origin although their reported - falls had been widely separated both in time and in space. - - Finally, said Howard, it was quite possible that the stones had really - fallen from the sky. - -Howard’s views were soon put to the test. Shortly after the publication -of his important paper, a shower of stony meteorites fell near L’Aigle, -France, on April 26, 1803. This event was carefully investigated by -French scientists, and they reluctantly admitted that about 3,000 stones -actually had fallen within an oval-shaped area about 6 miles long by 2 -miles wide. This shower of meteorites had been accompanied by the same -light and sound effects mentioned in many of the old meteorite-fall -reports collected by Chladni, effects now recognized as characteristic -of the infall of meteorites upon the earth. The evidence was -overwhelming—stones really did fall from the sky. In the camp of the -enemy, so to speak, the reality of meteorite falls was established once -and for all! - - - - - 12. THE MODERN VIEW - - -After the L’Aigle shower of 1803, a whole new era opened in the study of -meteorites. No longer did scientists hold these objects up to ridicule -and scorn. Instead, they came to regard meteorites as well worth -collection and careful study. - -The Vienna Museum, the British Museum, the Paris Museum, the Academy of -Science of St. Petersburg (now Leningrad), and the U.S. National Museum -began to build up splendid meteorite collections. 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. - -From this period we can date such milestones of progress in meteoritics -as: - - The discovery of the beautiful and significant Widmanstätten patterns - characteristic of the majority of the irons, and the less spectacular - but equally important lines named for J. G. Neumann, the German - meteoriticist who discovered them, in 1848, in the Braunau meteorite. - - The realization that there were many different kinds of meteorites and - that these diverse objects were very important to an understanding of - the internal structure and origin of the earth, and perhaps of the - Solar System and the wider cosmos as well. - - Tentative explanations of the violent and terrifying light and sound - effects connected with meteorite falls. - - Tentative explanations of such oval-shaped areas as shown above. - - [Illustration: Typical distribution of meteorite fragments according - to size, within oval-shaped area of fall. The larger masses of the - shower carry farther on, in the direction of the motion of the - meteorite. As early as 1814, investigators had noted this - peculiarity of meteorite-shower distributions. See pp. 32, 89, 94.] - -By 1850, A. Boisse, an early French geologist and meteoriticist, had put -forth the basic _meteorite-planet_ hypothesis. According to this theory -of his, meteorites are the fragments of a planet[12] that formerly -orbited between Mars and Jupiter in what is now called the “asteroid -belt.” And untold millions of years ago, this planet was shattered by -some unknown but very great force, possibly collision with another -celestial body. - -The structure of the meteorite-planet was considered to have been very -much like that of the earth. The various divisions of recognized -meteorites were believed to be representatives of the several -concentric, or nested, shells of material originally making up the -destroyed planet. These shells were progressively less dense with -increasing distance from the center of the planet. - -Today Boisse’s theory is one of the most widely accepted as an -explanation of at least one major category of the meteorites. Some -modern investigators would insist that the meteorite-planet had a thin -outer glassy shell from which the tektites came. - -Most of the larger fragments of the meteorite-planet, now called the -_asteroids_, move so that the average asteroidal orbit very closely -approximates the orbit of the original planet. But many of the smaller -fragments follow paths in space that differ considerably from the -original meteorite-planet’s orbit. Even some of the asteroids behave -this way, either because of the high speeds they acquired at the time of -disruption of the meteorite-planet, or because of the later influence of -the major planets and particularly of the giant planet, Jupiter. - - [Illustration: A diagram (not drawn to scale) showing position of - asteroid-belt with respect to the orbits of Mars and Jupiter. The - asteroids with average orbits move within this belt. The non-typical - asteroid indicated follows an orbit that brings it well inside that - of the earth. There are a number of asteroids with such peculiar - orbits. It is possible that in the past a nickel-iron asteroid in - one of these orbits collided with the earth and produced the Canyon - Diablo meteorite crater.] - -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. For the extensive -mining operations carried out there during the last half-century have -shown that the projectile responsible for this greatest of all -meteoritic shell-holes in the face of Mother Earth was a mass of solid -nickel-iron, which in all likelihood was core material. - -The lengthy and costly series of mining operations at Canyon Diablo were -all undertaken in the hope of locating the “main mass” of this huge -projectile and thus of opening up what might be called a cosmic-lode of -quite valuable metals. Unfortunately, the miners overlooked the fact -that impacts at meteoritic speeds produced almost incredible amounts of -heat. Even the solid iron meteorites are vaporized and widely dispersed -at the temperatures resulting from such impacts, as we have seen was the -case at Wabar (see Chapter 4). So it was at Canyon Diablo. - -The idea of a cosmic-metal mine might at first strike some readers as -too futuristic to take seriously. But the necessity for catching a -core-fragment before it enters the consuming atmosphere of our planet is -really nothing new. As far back as 1939, the senior author had occasion -to point out that if we wish to start a successful cosmic-metal mine, we -must catch our core-fragment before it is turned into unminable vapor. -This point will come up again in the next chapter. - - [Illustration: Cross-section of Boisse’s hypothetical - meteorite-planet. Fragmentation of this sphere was believed to have - given rise to the following divisions of meteorites: - - The _iron_ meteorites came from A, the dense nickel-iron core. - - The stony-iron meteorites came from B, the intermediate zone of - cellular nickel-iron and silicate minerals. - - The _stony_ meteorites came from C, the outer zone of silicate - minerals in which relatively little or no nickel-iron is present. - The chondrites were believed to come from the inner portion of this - zone; the achondrites, from the outer portion.] - -There are several other theories of the origin of meteorites interesting -enough to mention. The early view that the meteorites were debris thrown -out by ancient volcanoes on the moon or recent ones on the earth came to -be discredited largely on physical grounds. On the other hand, extremely -violent _primordial_ volcanoes on the earth (not the weak ones of -historic times, like Aetna or Vesuvius) could have ejected material that -in much later times fell, and continues to fall back on our globe. This -theory has not been ruled out and it still receives support, for -example, from some authorities in the U.S.S.R. These same Russian -scientists take most seriously a suggestion that the meteorites (and -comets as well) were thrown out by volcanoes believed to exist on the -planet, Jupiter—a theory dating back almost a century to the English -astronomer, R. A. Proctor. - -Some scientists believe that meteorites represent the congealed remains -of gaseous bolts of matter ejected by the sun. Others interpret them as -fragments of comets that have been torn apart by passing too close to -the sun, which is the most powerful gravitational center in the Solar -System. - -Chemists, geologists, astronomers, and physicists—as well as the -meteoriticists themselves—are constantly working toward a solution of -the problem of the meteorites. Where do these bodies come from? What can -we learn from them about their age and origin and about the age and -origin of our Solar System? Years may be required, but eventually the -riddle of the meteorites will be solved by the patient, concerted -efforts of men and women of science. - - [Illustration: Collapsed mine buildings in the bottom of the Canyon - Diablo meteorite crater. A shaft was put down here in one of several - unsuccessful attempts to locate the main mass of the meteorite. See - pp. 44-52.] - - - - - 13. PRESENT AND FUTURE APPLICATIONS - - -So far we have considered what might be called the “pure” rather than -the “applied” side of the study of meteorites. The investigator in any -pure science asks of a new discovery, “What does this tell me about the -universe? How does it better help me to understand the laws of nature?” -Of the same discovery, however, the worker in an applied science will -ask, “What practical use can be made of this gain in knowledge? What can -it be made to do for mankind in general?” - -These questions reveal a decided difference in viewpoint, but this -difference does not reflect unfavorably on either class of scientists. -In fact, there is a great deal of truth in the saying “Today’s pure -science is tomorrow’s applied.” Actually, ways and means of taking -advantage of seemingly useless scientific discoveries are constantly -being found. The most famous example of this principle is the -development of the atomic bomb from the results of Einstein’s researches -in the abstract field of relativity. Here the seemingly mystic formula E -= mc² came to have far-reaching practical applications indeed! - -Meteoritics has some exceedingly practical applications. Far from being -completely “out of this world”—as the recovered meteorites themselves -originally were—this science has been and can be made to serve mankind -in a number of rather unexpected ways. Meteoritics, the onetime -“stepchild of astronomy,” is currently being regarded with -ever-increasing respect by scientists and engineers working in many -different fields. - -Consider, first of all, the stainless steels that are so widely used in -modern industry, and even the fine satin-sheen stainless “silverware” -that graces our dining tables. These have wisely been patterned after a -natural alloy with lasting qualities of strength, tenacity, and -resistance to corrosion. This natural alloy is the one making up the -iron meteorites. - -Its toughness and durability became well known wherever attempts were -made to section these metallic meteorites. Specially designed and -extra-powerful sawing equipment is required to slice meteoritic iron, -and even with it, progress is painfully slow. So astounded were those -who first tried to cut iron meteorites with ordinary metal saws that one -of the earliest practical results was the development of battleship -armor plate composed of a commercial alloy called “meteor steel,” which -mimicked the composition of the iron meteorites. - -Of course, a good deal of the difficulty of sectioning meteorites arises -from the fact that those doing the cutting are trying hard not to waste -valuable meteoritic material. Every precaution is taken to keep the -amount of “sawdust” to a minimum, for such finely ground up and -contaminated meteoritic material is of little scientific use. And, in -addition, scientists must guard against heating meteorites to high -temperatures because such heating destroys the delicate internal -structure of the masses. If these two considerations (loss of material -and overheating) were unimportant, even a large meteorite could easily -be divided up by use of such high-powered oxyacetylene torches as are -used to dissect huge obsolete battleships. - -At the Institute of Meteoritics, a thin, water-cooled blade of soft iron -is driven slowly back and forth by an electric motor. Carborundum grit -in water suspension is fed evenly into the narrow cut over its entire -length. This grit becomes imbedded in the lower edge of the soft iron -blade, which then acts as a “many-toothed” metal saw. Several meteorites -can be sectioned simultaneously by this multiblade saw. In the future, -such newly developed methods as high-speed particle jet streams or -ultrasonic devices may be used to section meteorites both rapidly and -economically. - -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 first study of this type was made in May, 1948, at the Institute for -Nuclear Studies of the University of Chicago (now the Enrico Fermi -Institute). Scientists made radioactivity tests on samples of the Norton -County meteorite donated for this purpose by the Institute of -Meteoritics and air-expressed to Chicago because of the intense interest -in the radioactivity question. In October, 1949, English investigators -ran similar tests at the Londonderry Laboratory for Radiochemistry, -Durham, England, on samples of the freshly fallen Beddgelert, North -Wales, meteorite discussed on pp. 69-70. The results of these two -pioneer studies were negative because the “Model-T” instruments -available in 1948 and 1949 were not sensitive enough to detect the -relatively low radioactivities present. - - [Illustration: The 6-blade meteorite gang-saw in the machine shop at - the Institute of Meteoritics.] - -In 1955, however, scientists at Purdue University, using more refined -counters, studied small nuggets of nickel-iron, also from the Norton -meteorite. This time, the results of the radioactivity tests were -positive. The investigators detected tritium (an isotope of hydrogen -produced by cosmic-ray bombardment) in the samples. Furthermore, the -_amount_ of this rare isotope present indicated that the intensity of -cosmic radiation outside the earth’s atmosphere may be very much higher -than had previously been thought possible. “Forewarned is forearmed,” -and from the standpoint of future astronauts, this is as practical a -result as one could wish for! - -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. - -Suppose that extra-sensitive instruments were designed to pick up and -measure the radioactivities. Suppose further that these instruments were -mounted in a space-probe put in an orbit circling closely about the -moon. Plans for such a project are now under way. What types and -intensities of lunar radioactivities might such probe-mounted -instruments record? - -Until such a space-probe becomes available, earth-bound space-scientists -are seeking at least a preliminary answer to this question. They are -doing this by investigating the natural “probes” that have come to us -from space—the meteorites. - -Investigators have undertaken such studies very recently by employing a -new radiometric method technically called _gamma-ray spectroscopy_. Work -of this sort has been and is being done at the Los Alamos, New Mexico, -Scientific Laboratory on scores of meteorite and tektite specimens -loaned to the Laboratory by the Institute of Meteoritics. Some of the -individual meteorite specimens tested weighed as much as 37 pounds, and -are probably the largest single extra-terrestrial masses yet tested for -cosmic ray-induced radioactivities. - -Let us turn now to another important application of meteoritics. Any -body in motion through the air or in space has a “striking power” of -sorts. For some objects, this striking power, which is technically known -as _ballistic potential_, is very weak, as in the case of silky -milkweed-down drifting through the air. 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. - -For this reason, the speeds of meteorites are very important to -scientists responsible for rocket flights and for keeping satellites -aloft over long periods of time. Clearly, these men must have as -accurate information as possible on where and how fast meteoritic -particles are moving, so as to chart the safest routes for spaceships, -and to develop satisfactory means of protecting rockets and satellites -against the effects of bombardment by the smaller meteorites. For these -“small-fry” cosmic missiles are so numerous that many of them are sure -to be encountered even in brief flights outside the earth’s atmosphere. - -Such information might also prove valuable in the future to the crews of -spaceships on long flights into deep space. Such men may face the life -or death problem of taking successful “evasive action” against giant -meteorites that will seem like flying hills and mountains. - -A strong parallelism exists between a meteorite fall and the re-entry of -a nose-cone or data-capsule into the atmosphere. To a considerable -extent, the difficult problems connected with the latter are being -attacked at present through careful studies of meteorites. From the -air-sculptured shapes of meteorites, their crustal flow patterns, and -the thicknesses and types of fusion crusts they show, scientists are -learning a great deal about certain factors connected with the re-entry -problem. These factors include rate of vaporization, effects of extreme -temperatures, and types of sculpturing to be expected as a result of -encountering the resisting molecules of the atmosphere. - - [Illustration: Relationship between (A) the trajectory of a falling - meteorite, and (B) the re-entry stage of a V-2 rocket. The solid - lines indicate the similar portions of the two trajectories. - - - A. A METEORITE FALL - B. A V-2 RE-ENTRY] - - -One of the most obvious applications of meteoritics in the future will -grow out of the well-known fact that our earthly resources of many -strategic materials—especially metals like iron and nickel—are fast -becoming exhausted. The population of the earth is increasing at a mad -pace, and an end to metal-consuming wars is still not in sight. 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. Once he has given an answer, the space -engineers will take over, and mining operations will be started on the -unlimited sources of essential metals to be found in outer space. - -Initially, no doubt, metal recoveries will be freighted back to earth in -rocket-load lots. 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. - -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. The rocket crews of -day-after-tomorrow will no doubt be equally fearless and resourceful as -they navigate the sea of space, intent on capturing the great “metal -mines” of the future. - -The experience gained in such space-mining ventures will then be carried -over into expeditions to ensnare the larger stony-iron meteorites. These -masses of iron and stone will offer less favorable mining possibilities, -but they can be turned into rocket-propelled and guided de luxe -space-cruisers. By this term, we do not mean that these natural -space-ships will house all the luxuries of the ocean-liners advertised -in the travel magazines. Rather, we see them as providing roomy, -comfortable “underground” living quarters. Furthermore, their occupants -will be adequately protected by great thicknesses of metal and rock from -the injurious radiations of empty space, and the meteorites that make -the term “empty space” something of a misnomer. - -Initially, such worlds-in-miniature will be much sought after as -laboratory sites where the more violent and dangerous of the many -experimental tests which venturesome man will wish to conduct can be -carried on without danger to the close-packed billions populating the -then-crowded earth. - -Later on, these meteorites-turned-into-space-ships may be used to -explore the dangerous and faraway corners of the Solar System, since the -very substance of each massive meteoritic rocket-body will serve as an -adequate and handy source of fuel supply. - -When men have learned to live on such “homes away from home,” it is -quite possible that the larger of these modified meteorites, after their -interiors have been opened up for occupancy by the inroads of the -fuel-hungry rocket-motors, may be steered into neighborly orbits about -old Mother Earth. Here, these “natural” satellites will assume the -unexciting but necessary roles of the extra living quarters that by then -will be so urgently needed to accommodate the mushrooming population of -the world of the future. - -People who live in these super-urban outliers of Mother Earth may take -the same pride in their natural, if converted, homes as many former city -dwellers now take in the old-fashioned sprawling farmhouses they have -rebuilt and occupied. Perhaps one of your descendants will live in such -a meteorite-orb, and occasionally point the finger of scorn at the more -elegant but unpleasantly overcrowded artificial satellites preferred by -those migrants from teeming earth who lack the true pioneering instinct. -Who knows! - - - - - FOR FURTHER READING - - -If you are especially interested in meteoritics, you already may have -read some good books on general astronomy. There are many and most of -them are not too advanced for the beginner. Unfortunately, these books -devote but little space to meteoritics, the “Johnny-come-lately” of -astronomy. Almost all of the writings on meteors and meteorites you will -find largely profitable to read are in professional meteoritical -publications. A selected list of such publications, containing much or -at least a worthwhile amount of material you will now be able to -understand, is given below. Your chief difficulty in using this list -will be in finding some of the more important items in the holdings of -your public library, unless it is a large and well-stocked one. Your -librarian, however, may be able to help you get the item from some other -library—perhaps from that of a nearby university or college. - - - METEORIC ASTRONOMY - -MEBANE, A. D. “The Canadian Fireball Procession of 1913, February 9,” -_Meteoritics_, Vol. 1, No. 4 (1956), pp. 405-421. Eyewitness accounts of -the most famous fireball procession on record. - -OLIVIER, C. P. _Meteors_, Williams and Wilkins, Baltimore, 1925. An -exhaustive survey of work done by visual meteor-observers. - -SCHIAPARELLI, G. V. _Shooting Stars_, a translation by C. C. Wylie and -J. R. Naiden, published in the _Proceedings, Iowa Academy of Science_, -Vol. 50 (1943), pp. 48-153. A pioneer treatise, dated 1867, which is -basic to later work in this field. - -WHIPPLE, F. L. “Photographic Meteor Studies, I,” _Proceedings, American -Philosophical Society_, Vol. 79, No. 4 (1938), pp. 499-548. Fundamental -paper on the subject. Of the six meteors analyzed, five followed -elliptical orbits and one, a strongly hyperbolic orbit. - - - METEORITES - -FARRINGTON, O. C. “A Catalogue of the Meteorites of North America to -January 1, 1909,” _Memoirs, National Academy of Sciences_, Vol. 13 -(1915). Contains fascinating accounts of the phenomena connected with -meteorite falls, interspersed with lengthy technical chemical and -microscopic studies of meteorites. - -FARRINGTON, O. C. _Meteorites_ [published by the author], Chicago, 1915. -The classic American work on meteorites. The first half of the book is -popular; the last half is technical. - -HEY, M. H. and PRIOR, G. T. _Catalogue of Meteorites_, William Clowes & -Sons, London, 1953. An exhaustive catalog of all recognized and also, -unfortunately, of many doubtful meteorite falls and finds, from the -beginning of the historical record up to December 1952. - -LAPAZ, LINCOLN. “The Achondritic Shower of February 18, 1948,” -_Publications, Astronomical Society of the Pacific_, Vol. 61 (1949), pp. -63-73. - -LAPAZ, LINCOLN. “The Effects of Meteorites upon the Earth,” _Advances in -Geophysics_, Vol. 4, edited by H. E. Landsberg, Academic Press, New -York, 1958, pp. 217-350. A monograph covering such topics as meteorite -hits upon buildings and people, meteorite detectors, and the nature and -age of meteorite craters. - -LEONARD, F. C. “The Furnas County, Kansas, Achondritic Fall (1000,400),” -_Contributions, Meteoritical Society_, Vol. 4 (1948), pp. 138-141. This -paper and the eighth item, above, discuss the phenomena of the fall of -the largest aerolite so far recovered anywhere in the world. - -MERRILL, G. P. “The Story of Meteorites,” _Minerals from Earth and Sky_, -Vol. 3, Part I, Smithsonian Scientific Series, 1929, pp. 1-163. A -chiefly popular survey of the subject by a master meteoriticist. - -PERRY, S. H. _The Metallography of Meteoric_ [meteoritic] _Iron_, U. S. -National Museum Bulletin No. 184 (1944). A summary of knowledge on the -subject, supplemented by exceptionally fine photographs of etched -meteorite sections. - -SWINDEL, G. W., JR., and JONES, WALTER B. “The Sylacauga, Talladega -County, Alabama, Aerolite: A Recent Meteoritic Fall that Injured a Human -Being,” _Meteoritics_, Vol. 1, No. 2 (1954), pp. 125-132. - -WHITE, C. S. and BENSON, OTIS O. (editors) _Physics and Medicine of the -Upper Atmosphere_, University of New Mexico Press, Albuquerque, 1952. -See Chapter X, “Meteoritic Phenomena and Meteorites,” by F. L. Whipple, -pp. 137-170; and Chapter XIX, “Meteoroids, Meteorites, and Hyperbolic -Meteoritic Velocities,” by Lincoln LaPaz, pp. 352-393. Modern views on -the meteorite velocity controversy. - - - METEORITE CRATERS - -LAPAZ, LINCOLN. “The Craters on the Moon,” _Scientific American_, Vol. -181, No. 4 (1949), pp. 2-3. A popular exposition of the -Bénard-Wasiutynski theory of the origin of the ordinary (nonrayed) -craters on the moon. - -SPENCER, L. J. “Meteorite Craters as Topographical Features on the -Earth’s Surface,” _Geographical Journal_, Vol. 81 (1933), pp. 227-248. -The classic paper on terrestrial meteorite craters. - - - METEORITIC DUST - -BUDDHUE, J. D. _Meteoritic Dust_, The University of New Mexico Press, -Albuquerque, 1950. An account of the various techniques used in -collecting and studying meteoritic dust; and also of the conclusions -drawn from the study of such dust. - - - - - INDEX - - - A - achondrites, 126, 163, 178 - Adelie Land stone, 78 - Adrar iron, 38, 40 - aerolites, 178, 179 - _see also_, stones, meteoritic - age of meteorites and/or craters, 50, 52 - Aggie Creek iron, 76 - Ahnighito iron, 36, 128 - Algoma meteorite, 75 - “Alley Oop’s shillelagh,” 126 - altitude, 88, 90, 105, 106 - American Meteor Society, 116 - American Museum of Natural History, 37 - Anderson Township meteorites, 76 - Andhâra stone, 147-8 - Andromeda, Great Spiral Nebula in, 2 - Andromedid shower, 153 - anthills, meteorites in, 128 - anti-matter, 58-60 - Aouelloul crater, 65 - appearance and disappearance of meteors, 86, 94, 106 - applied science, 166 - archeologists, 76, 150 - areas of fall, 13-4, 24, 26, 32, 89, 94, 159 - armor plate, 167 - asteroid belt and orbits, 160-1 - astronautics, 110, 168, 170-6 - ataxites, 120 - Athens, multiple fireball over, 149 - australites, 134, 140 - azimuth, astronomical, 88 - - - B - Bacubirito iron, 128 - Bald Eagle iron, 76 - ballistic potential, 171 - Baxter stone, 73 - Bear Lodge iron, 76 - Beddgelert stone, 69-70, 73, 168 - bediasites, 136, 137 - Belly River stone, 131 - Benares meteorite, 156 - Bendego iron, 128 - Benld stone, 73 - Benson, O. O., 179 - Bethlehem stone, 73 - betyls, 148, 150 - Bible, meteorite mentioned in, 147 - Bielid shower, 116 - “blackfellows’ buttons,” 134 - Black Stone of the Kaaba, 147 - Boisse, A., 160, 163 - bolides, 102, 151 - Braunau iron, 73 - Brenham craters and meteorites, 52, 65, 66, 78 - Box Hole Station crater, 65 - Bridgewater meteorite, 75 - British Museum, 136, 158 - Buddhue, J. D., 179 - - - C - Campo del Cielo craters, 50, 65 - Canyon Diablo crater, 44-52, 65, 66, 75, 96, 161, 162, 165, 174 - Cape of Good Hope iron, 150 - Cape York iron, 36, 37 - Carlton meteorite, 75 - Casas Grandes iron, 76 - charms, meteorites used as, 134, 136 - _see also_ sacred meteorites; superstitions - Chesterfield meteorite, 75 - Chladni, E. F. F., 155-7 - chondrules and chondrites, 124-6, 163 - Chubb crater, 52-4 - coins depicting meteorites, 148, 150 - collection of meteorites in institutions, 20, 32, 34, 37, 38, - 40-1, 90, 136, 158 - comets, 114, 140, 164 - composition of meteor-forming particles, 160-7 - composition of meteorites, 118-26, 163, 179 - composition of tektites, 136-8 - Constantia stone, 74 - contraterrene matter, 56, 58-60 - convection-current hypothesis, 63-4 - cosmic metal mine, 162, 174-6 - cosmic rays, 168-71 - craters, 17, 18, 20, 42-65, 66, 96, 143, 178, 179 - - - D - Dalgaranga crater, 65 - daubreelite, 124 - destruction by meteorites, 11, 15, 16-19, 54-7, 68-70, 73-4, 178 - diamond-bearing meteorite, 82 - direction measures, 23, 24, 86-9, 110 - distribution of meteorites, 66-68, 72, 140-3, 159 - dog and meteorite, 73 - doubters of meteorites, 154-7 - “dumbbells,” 135, 136 - “dust balls,” 106 - dust, meteoritic, 102, 116-7, 179 - - - E - “earth-rings,” 142 - earth-trace, 92 - eating a meteorite, 82 - Einstein, A., 166 - elements in meteorites, 118-24 - elements in meteor-forming particles, 107 - elevation, apparent, 88, 90 - _see also_ altitude - “end-point,” 16, 86-91 - Enrico Fermi Institute, 168 - Ensisheim stone, 152, 154 - Eta-Aquarid shower, 114 - etching meteorites, 119-123 - evaporation, _see_ vaporization - “explosions” of meteors and/or meteorites, 18, 23, 25, 55, 56-60, - 63, 86, 92 - - - F - fall, determining area of, 13-14, 24, 26 - _see also_ oval-shaped areas of fall - falls, witnessed, 11-22, 23-34, 67, 68-72, 82, 84-95 - Farrington, O. C., 178 - farmers as meteorite finders, 28, 30, 75-6 - Fermi (Enrico) Institute, 168 - fireballs, 2, 10, 11-13, 23-5, 54, 69, 84-92, 102, 106, 149, 151 - fishermen net meteorite, 78 - fixes, 84-90 - “flanged buttons,” 135, 136 - flight-path, _see_ trajectory - Flows meteorite, 82 - footwarmer, meteorite used as, 78 - “fossil” meteorites, 144-6 - funnels, impact and penetration, 20, 29, 32, 33, 42, 44 - Furnas County stone, 29, 31, 32-4, 128, 178 - _see also_ Norton County fall - fusion crust, 20, 21, 130, 132, 140, 148, 172 - - - G - Galle, J. G., 92 - gamma-ray spectroscopy, 171 - Geminid shower, 114 - Giacobinid shower, 103, 114, 115 - Giacobini-Zinner comet, 114 - glass, 138, 145 - _see also_ silica-glass; tektites - Glorieta iron, 126 - great-circle distributions, 140-3 - - - H - Harvard meteor-photographs, 110-1 - Haviland craters, 50, 52, 65, 66 - Hayden Planetarium, 129 - height, 88, 90, 105, 106 - Henbury craters, 50, 65 - Hey, M. H., 178 - hexahedrites, 119, 120 - Holbrook stone shower, 128 - Howard, E., 155-7 - hunting meteorites, methods of, 84-100 - - - I - “ices,” 106 - Illinois Gulch iron, 76 - impactites, 143-5 - India, Museum of the Geological Survey of, 41 - Indians, 41, 76, 150 - Institute for Nuclear Studies, 168 - Institute of Meteoritics, 5, 24, 26-32, 80, 84, 96, 168, 169, 171 - intersecting lines of sight, 84-90 - interstellar space, 92, 171 - irons, 19, 36, 37, 39, 40, 41, 48, 73, 75, 76, 78, 82, 99, 116, - 118, 120, 121, 128, 129, 133, 143, 150, 155, 163, 167, - 174-5, 179 - - - J - Jones, W. B., 179 - Jupiter, 102, 142, 160, 161, 164 - - - K - Kaalijarv crater, 65 - kamacite, 124 - Kasamatsu stone, 74 - Kayser, E., 92 - Kenton iron, 75 - Kilbourn stone, 74 - Klepesta, J., 2 - Krasnoyarsk iron, 155 - - - L - laboratory procedures, 5, 81, 83, 118, 120, 128, 167-71 - La Caille meteorite, 78 - L’Aigle stone shower, 157, 158 - Lake Murray iron, 77, 79, 80-3 - Lake Okeechobee stone, 78 - LaPaz, L., 178, 179 - largest meteorites, _see_ weights and weighing of meteorites - Leningrad (St. Petersburg), Academy of Science of, 158 - Leonard, F. C., 178 - Leonid shower, 114, 115 - Lick Creek iron, 76 - Londonderry Laboratory for Radiochemistry, 168 - Los Alamos Scientific Laboratory, 171 - “lost” meteorites, 38, 40, 41, 80, 82, 95 - lunar craters, 60-4, 179 - _see also_ moon, craters on - Lyrid shower, 112, 114 - - - M - magic attributed to meteorites, _see_ superstitions - Mars, 160, 161 - “Martian spaceship,” 60 - Maximilian I, 152-4 - Mazapil iron, 116 - Mebane, A. D., 177 - Medvedev, P. I., 10 - Merrill, G. P., 178 - Mesaverde iron, 76 - metals, meteorites as sources of, 174-5 - meteorite detectors, 48, 52, 96-100, 178 - meteoriteless meteorite crater, 56 - meteorite-planet hypothesis, 140, 160, 163, 174 - meteorite showers, 73-4, 128, 157, 158, 159 - meteorites, true or false, 130-3 - meteoritics, 5, 104, 166-7 - meteors, 101-17 - meteor showers, 103, 111, 112-116, 117, 152, 153 - meteor steel, 167 - micro-meteorites, _see_ dust, meteoritic - minerals in meteorites, 120-6, 156, 163 - miners as meteorite finders, 70, 76, 144 - mining in space, 162, 174-6 - Montezuma temple iron, 76 - moon, 60-4, 140, 170 - moon, craters on, 60-4, 179 - Morito iron, 128 - Moscow, Academy of Sciences at, 20 - Mount Darwin, Tasmania, crater, 65; - silica-glass, 143 - Mount Joy iron, 75-6 - Murfreesboro iron, 76 - - - N - “natural nuclear explosion,” 60 - Neumann, J., 158 - nickel-iron, 19, 32, 96, 98, 118, 120, 122, 123, 124, 126, 132, - 143, 150, 161, 163, 170, 174 - Norton County fall, 23-34, 90, 93, 94, 96, 126, 128, 130, 168 - Novo-Urei stone, 82 - - - O - obsidian mistaken for tektite, 138-9 - octahedrites, 120, 121 - Odessa crater, 43, 44, 52, 65, 66, 75 - oldest collection of meteorites, 76 - oldest crater, 52 - Olivier, C. P., 116, 177 - Opava irons, 76 - orbits, 108-112, 160, 161 - origin of meteorites, 160, 163, 164, 174 - Orionid shower, 112, 114 - oval-shaped areas of fall, 32, 89, 94, 159 - ownership of meteorites, 36, 38 - - - P - Pallas, P. S., 155 - pallasites, 122, 155 - Pantar stone shower, 74 - parallax and parallactic displacement, 105, 106 - Paris, Museum of Natural History at, 38, 158 - paths of meteors, 84-94, 116 - _see also_ earth-trace; orbits; speeds; trajectory; velocity - patterns, structural, 120, 121, 172 - Pawnee Indians, 41 - Peary, R. E., 36, 37, 128 - Perry, S. H., 179 - Perseid shower, 114, 115 - person struck by meteorite, 70-2, 178, 179 - piezoglyphs, 131, 132 - Pittsburgh iron, 78, 80 - plessite, 124 - plotting meteor paths, 116 - Plymouth meteorite, 75 - Podkamennaya Tunguska fall, 50, 54-60, 65, 102 - polishing meteorites, 5, 118, 120, 123 - Port Orford stony-iron, 40 - Prague Observatory, 2 - Prior, G. T., 178 - Proctor, R. A., 164 - Pultusk fireball, 92 - Purdue University, 170 - pure science, 166 - “purloined” meteorite, 36, 39 - - - Q - Quadrantid shower, 114 - - - R - radiant of meteor shower, 112, 113 - radioactivities, 5, 60, 133, 138, 168, 170-1 - Rafrüti iron, 78 - rainfall, connected with meteor - showers, 117 - random distribution, 62 - ray-craters, 60-4 - recoveries of meteorites, 14-22, 24, 26-8, 31, 33, 35, 75-82, - 84-100 - Red River iron, 41 - re-entry, 172, 173 - reports, eyewitness, 23, 24, 84, 86, 90, 92, 94-5 - reversed matter, 56, 58-60 - Richland iron, 75 - Rigel, 92 - rocketry, 110, 174-6 - Rojansky, V., 58 - - - S - sacred meteorites, 147-50 - _see also_ superstitions - San Emigdio stone, 80 - satellites, man-made, 172 - Saturn’s rings, 142 - sawing meteorites, 81, 167-9 - Schiaparelli, G. V., 177 - Schmidt, J. F. J., 149 - schreibersite, 124 - Scottsville iron, 76 - Seeläsgen iron, 75 - Shakespeare, meteors mentioned by, 152 - shale balls, 48, 133 - shapes of meteorites, 18, 32, 126-8, 134-7, 140, 172 - Shirihagi iron, 150 - “shooting stars,” 104 - showers, meteor, 103, 111, 112-116, 117, 152, 153 - showers, meteorite, 73, 74, 128, 157, 158, 159 - Siena fall, 156 - Sikhote-Alin fall, see Ussuri - silica-glass, 50, 54, 143 - _see also_ glass; tektites - silicate-siderites, 122, 123 - Sirius, 92 - “skymarks,” 92 - smallest meteorites, 48, 128 - _see also_ dust, meteoritic - Solar System, 5, 111, 164, 175-6 - sounds made by falling meteorites, 11, 12, 24, 25,26, 94-5, 148, - 159 - space exploration and ships, 5, 168, 170-6 - space-probes, 170-1 - space mining, 162, 174-6 - spectra and spectrograms, meteor, 107 - spectroscopy, gamma-ray, 171 - speeds, 21, 32, 107, 108, 109, 110-12, 126, 172 - Spencer, L. J., 179 - stainless steel, 120, 122, 167 - stones, meteoritic, 28-34, 35, 70, 71-2, 73-4, 78, 80, 82, 118, - 120-4, 128, 130, 131, 132, 133, 148, 156-7, 163 - stony-irons, 40-1, 118, 122, 124, 163 - strata, effect of impact on, 43, 44-5, 48-51 - superstitions about meteors and meteorites, 25, 56, 82, 134, 136, - 147-52, 154 - swarms, meteorite, 50 - swarms, meteor-particle, 111, 112, 114 - Swindel, G. W., Jr., 179 - “swords from heaven,” 150 - Sylacauga stone, 71-2, 74, 179 - - - T - taenite, 124 - tektite-obsidian test, 138-9 - tektites, 134-146, 160 - tests for true meteorites, 130-3 - “thumb-prints,” 131, 132 - trajectory, 90, 92, 173 - tritium, 170 - Tucson iron, 128 - Tungus, _see_ Podkamennaya Tunguska - twice-found meteorites, 76 - Tycho, lunar ray-crater, 61 - - - U - University of California Radiation Laboratory, 58 - University of Chicago, 168 - University of New Mexico, 24, 30 - _see also_ Institute of Meteoritics - University of Nebraska, 30, 80 - U. S. National Museum, 40, 158 - Ussuri fall, 10, 11-34, 42, 50, 54, 65, 130 - - - V - vaporization, 102, 107, 116, 126, 128, 143, 145, 162, 172, 174 - velocity, 107, 108, 109, 171, 179 - Venus, 102, 162 - Verbeek, R. D. M., 140 - Vienna, National History Museum of, 41, 158 - volcanic theories, 138, 155, 156, 164 - - - W - Wabar craters, 50, 65, 143, 162 - Wasiutynski, J., 63-4, 179 - water, meteorites under, 78 - waves, air and water, 12, 54-5 - weather, effect of meteoritic dust on, 117 - weathering of meteorites, 38, 48, 52, 53, 54, 66, 133, 144 - weights and weighing of meteorites, 35, 36, 128, 130 - White, C. S., 179 - Widmanstätten pattern, 120, 121, 122, 158 - Whipple, F. L., 177, 179 - Willamette iron, 36, 128, 129 - Wold Cottage meteorite, 156 - Wolf Creek crater, 52, 53, 65, 75, 133 - - - Y - Yale University, 41 - young people and meteoritics, 23, 24, 28, 34, 39, 90, 98, 99, 116 - _see also_ reports, eyewitness - - - Z - Zhovtnevy Hutor fall, 82 - - - - - FOOTNOTES - - -[1]Also called _aerolites_. - -[2]The meteorites from this crater-producing fall have been found in - both Haviland and Brenham Townships, Kiowa County, Kansas. Either of - these names may therefore appear in the literature. - -[3]The meteorites from this crater-producing fall have been found in - both Haviland and Brenham Townships, Kiowa County, Kansas. Either of - these names may therefore appear in the literature. - -[4]453.59 grams = 1 pound. - -[5]A questionnaire for making an adequate report is obtainable by - request from the Institute of Meteoritics, The University of New - Mexico, Albuquerque. - -[6]Readers who are advanced enough in astronomy to attempt plotting the - meteor paths can get the proper star-maps and record sheets for this - purpose by joining the American Meteor Society. Members must be at - least 18 years old, but applicants between 14 and 18 can become - probational members. For details write to Dr. C. P. Olivier, - President, American Meteor Society, 521 North Wynnewood Avenue, - Narberth, Pennsylvania. - -[7]Quite recently, a fourth division, the _tektites_ (discussed in the - next chapter), has been recognized by some authorities. - -[8]Discussed in Chapter 12. - -[9]The Acts of the Apostles, 19:35. - -[10]Also _baetyl_ and _baetulus_, from the Greek word _baitylos_, a term - used for sacred meteorites and stones. - -[11]This metallic mass was the first stony-iron meteorite to be - identified as such. The _pallasites_, which make up an important - subdivision of the stony-iron meteorites, were named in honor of - Pallas. - -[12]Very recently, some authorities have concluded that there must have - been not one but several meteorite-planets. - - - Space Nomads - Meteorites in Sky, Field, and Laboratory - By Lincoln LaPaz and Jean LaPaz - -Meteorites are the real tokens of space! They are samples of cosmic -matter we can actually take in our hands. Science values them greatly as -specimens of _the only tangible_ substances we have from remote and -inaccessible regions of the universe. - -These mysterious “space nomads” are revealing to today’s scientists many -amazing and usable facts about conditions in outer space, about the age -of our Solar System, and even about the probable constitution of our own -home planet. - -This is an essential book for everybody who is keeping up with space -science and wishes to be well posted on these interesting but -potentially dangerous co-voyagers that the astronauts may encounter. - -You will also see in SPACE NOMADS: - -The awesome event a meteorite-fall can be, with its violent sound and -light effects, and its terrific impact. - -The excitement and the know-how of the hunt for these cosmic missiles. - -How to tell the difference between a true meteorite and a mistaken one. -Ditto, meteorite craters. - -How to make your own contribution to science by knowing the right way to -observe and report meteors and meteorites. - -What is inside them, and how they vary in content and structure. - -The moon as a meteorite target. - -The strange history of the subject—the amusing superstitions and -fantastic notions believed until recently about “shooting stars” and -“stones falling from the sky.” - -And more. - - -Here is an easy but sound introduction to the rapidly developing science -of meteoritics. All of the information is up-to-date, much of it -firsthand, for the authors are themselves professional meteoriticists. -Daily they are engaged in fieldwork, laboratory analysis, and advanced -research at one of the world’s chief centers for this study. (See back -of jacket.) - - A HOLIDAY HOUSE BOOK - 12 UP $3.95 - - _Jacket by Leo Manso_ - - [Illustration: HARVEY CAPLIN PHOTO - Lincoln LaPaz] - -On the moon is a ray-crater named LaPaz in honor of the man who has had -a major part in establishing the highly significant theory that the -lunar ray-craters were made by the impact of meteorites. Lincoln LaPaz -is a leading pioneer as well as a widely recognized authority in -meteoritics, an important branch of astronomy. He was born on Lincoln’s -birthday, in Wichita, Kansas, where he grew up. Although both his -master’s degree, at Harvard, and his doctorate, at Chicago, were in -mathematics, his chief interest since boyhood has been in meteorites and -meteors. Today he is Director of the Institute of Meteoritics at the -University of New Mexico, where he also heads the Division of Astronomy. - - [Illustration: RAVINI PHOTO - Jean LaPaz] - -Jean LaPaz was born in Hanover, New Hampshire. Since girlhood she has -been close to her father in his fascinating work. When she was a -high-school student in Ohio, she did some serious fieldwork as a member -of the Ohio State University Meteorite Expeditions. Later, she received -both a Bachelor of Science degree in geology and a Master of Arts in -English from the University of New Mexico. Science and Literature -continue to be her mutually favoring interests. - - - - - Transcriber’s Notes - - -—Retained publication information from the printed edition: this eBook - is public-domain in the country of publication. - -—Silently corrected a few palpable typos. - -—In the text versions only, text in italics is delimited by - _underscores_. - - - - - - - -End of Project Gutenberg's Space Nomads, by Lincoln LaPaz and Leota Jean LaPaz - -*** END OF THIS PROJECT GUTENBERG EBOOK SPACE NOMADS *** - -***** This file should be named 52848-0.txt or 52848-0.zip ***** -This and all associated files of various formats will be found in: - http://www.gutenberg.org/5/2/8/4/52848/ - -Produced by Stephen Hutcheson, Dave Morgan, and the Online -Distributed Proofreading Team at http://www.pgdp.net - -Updated editions will replace the previous one--the old editions will -be renamed. - -Creating the works from print editions not protected by U.S. copyright -law means that no one owns a United States copyright in these works, -so the Foundation (and you!) can copy and distribute it in the United -States without permission and without paying copyright -royalties. 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