*THREE STAGES IN METEORITE RESEARCH* by D.V.Djomin and V.K.Zhuravlyov Correspondence to: V.K.Zhuravlyov, Post Box 168, Novosibirsk 630058 Russia. e-mail: tunguska@locutus.nsu.ru ABSTRACT In the initial stage (1908 - 1949) of the research on the Tunguska Event the aim seemed simple: to find fragments of a giant meteorite. The second stage ( 1958 - 1993) was a period of the complex and many-sided explorations of the catastrophe region, computer processing of data, search of eyewitness communications, investigations of geophysical archives, and testing the validity of simple models that might explain the phenomenon. The third stage, in the view of the authors, began in 1994 and is a period of establishing an international data bank and use of system analysis as a key to a solution of THE FIRST STAGE of the Tunguska Event research may be considered as the interval between years 1908 and 1949. In 1908 the first letters of eyewitnesses had been received by the Irkutsk Observatory and had appeared in newspapers. In 1949 a published monograph by Eugene Krinov summarized the results of Leonid Kulik`s researches ( Krinov, 1949). In this stage, investigators generally accepted the traditional model: The phenomenon could be explained by a collision of Earth with a minor body of Solar System, either an asteroid or a comet. The main efforts of scientific investigation were the search for meteorites. The event occurred on 30 June 1908, but the search for eyewitnesses and for the site of the explosion over the taiga did not begin until 1921. In 1927 L. A. Kulik discovered the unique radial pattern of forest destruction. Its center was identified as the collision site of a presumed giant meteorite with Earth's surface. An aerial survey was made in 1938. Kulik organized the tasks of future expeditions, including the creation of trails, construction of small storage buildings, geodedical location markers, and establishing a grid system through the forest by cutting away trees. During this stage, they made a rough map of the region and interviewed eyewitnesses. THE SECOND STAGE may be considered as interval between 1958 and 1993 years (Andreev at al., 1994, Vasilyev, 1985). The search for fragments of a giant meteorite was repeated, and again the result was negative. Computer analysis of expedition data had ascertained the altitude and energy of the explosion over the taiga (6 +- 1 km, 20 - 40 megatons of TNT equivalent). The moment of the explosion was established precisely, based on geophysical records: 00 h 14.5 +- 0.8 min. of Greenwich time (Pasechnik, I. P., 1976). The search for meteorite fragments now seemed fruitless, because computation of the explosion parameters, together with the nature of the geophysical records, revealed that the density of energy at the moment of the explosion was extremely high. Since 1960, the main trend of the investigations has become ecological; i.e., oriented toward forestry, marsh research, and the exploration of traces and signs of the explosion discovered in the biosphere and lithosphere. During that time scientists in Tomsk, Moscow, and Irkutsk also began a search in the scientific archives for geophysical and meteorological evidence of the unique cosmic event (Plekhanov et. al., 1961, Vasilyev and Fast, 1972). During the second stage the center for research of the Tunguska Event shifted from Moscow to Tomsk, where the Interdisciplinary Independent Expedition (IIE) group was established. This consists of scientists who volunteer their services in field research in the taiga, at computer terminals, and in analytical laboratories. To this day the Tomsk group remains the center of the IIE, but branch groups are active in various cities of the former Soviet Union: in Moscow, St. Petersburg, Novosibirsk, Kiev, Ashkhabad, Ust-Kamenogorsk, Omsk, and others. The IIE has made numerous investigations at the site and in control regions. These investigations are unprecedented, considering the volume of data collected, the duration of research, and the broad spectrum of scientific disciplines. Important contributions in investigation of the problem have been made by scientists from Moscow, including Yu. Emelyanov, V. Bronshten, V. Korobeynikov, and others. A few expeditions have been organized by cosmochemists from Kiev (Institute of Geochemistry and the Physics of Minerals). Working independently from the IIE is a small group from Tver under the leadership of geophysicist Aleksey Zolotov. His contribution to a solution of the Tunguska problem has been much underestimated (Zolotov, 1969). Additionally, the publication of a paper written by American scientists who investigated radiocarbon traces of the Tunguska explosion in trees has stimulated great interest among other investigators (Cowan C. et al., 1965 ). The second stage has been characterized by a pluralism of scientific methods and ideas ranging from highly refined techniques in nuclear research and mathematical methods in population genetics to thermoluminescence, and even dowsing; and from hypotheses about comets to the possible nuclear explosion of an astronomical object of an unknown nature. THE MAIN DIRECTIONS OF INVESTIGATIONS HAVE BEEN: * a general mapping of damaged area (forest fall, signs of fire, burn scars on trees) * mutations in flora and fauna * the search for cosmic body matter in soil, peat, tree resin, tree rings, and the study of isotope anomalies in the biosphere * anomalies in thermoluminescence of minerals in soil and in rocks, magnetic effects of the explosion (records by magnetographs and by paramagnetic particles in soil ) * fluctuations in background radiation * collection of archival data from observatories around the world * interrogation of eyewitnesses over a vast area from the Yenissey to the Lena Rivers. THE MOST SIGNIFICANT RESULTS OF THE SECOND STAGE (published in the proceedings of the Institute of Geology and Geophysics at Novosibirsk and in other Russian publications, 1960s through 1990s ): proof of the high-altitude explosion of a bolide, 30 June 1908, by various methods (altitude of 6 + - 1 km) estimate of explosion energy by various methods ( 20 to 40 megatons) discovery and analysis of magnetograms that prove to be identical to magnetograms generated by man-made magnetic storms resulting from nuclear tests correlations of thermoluminescent anomalies with the distribution of tree burn scars prominent mutant anomaly of pine trees over the site of the explosion discovery of unusual cosmochemical anomalies of lanthanoids in the soil and peat of the area Spectral analysis has identified chemical elements claimed to be probable traces of matter of the Tunguska object: Yb, Eu, Tm, La, Ce, Na, Zn, Pb, Ba, Sr, Ta, W, Ag, Au, Ir, Ni, Co, and C ( carbon probably in the form of graphite). The microscopic silicaceous spherules discovered may also be the melt dust of the cosmic object. The Italian expedition to the Tunguska site in 1991 provided new and interesting data (G. Longo et al., 1994). Analytical electron microscopy showed that micro-sized particles trapped in tree resin at the time of the explosion contain chemical elements typical of stony meteorites. Unfortunately, analysis for the presence of lanthanoids has not been done as of this writing. An unexpected outcome of the data of the many interdisciplinary explorations conducted with modern scientific techniques at the second stage is the contradiction of earlier simple models. Neither the cometary model nor the stony asteroid model is supported by all the data, accumulated by three generations of 20-th century scientists (Zhuravlyov and Zigel, 1994). THE THIRD STAGE in the Tunguska meteorite research is now beginning. The report of Vladimir Vorobyev, presented during the international conference (Vorobyev, 1994), may be considered the starting point of this stage. Vorobyev drew to the attention of the scientific community the scientific and cultural importance of the vast store of data so far collected about the Tunguska Event. Therefore, it is necessary to establish a computer data bank of Tunguska phenomenon and integrate those data with geo-information systems. System analysis is now the key direction. Under the initiative of Academician Professor Anatoly S. Alekseev, director of the Computing Center in Novosibirsk Academgorodok, the organization of an international data bank ("Tunguska Catastrophe") on the Internet has begun. It represents work of the international scientific community to make this unique data available for assimilation and analysis for the reconstruction of the Tunguska phenomenon. Now users of the Internet can have access to this information in order to adapt it to model ecological, geophysical, medical-biological, and other aspects of the Tunguska Event Additionally, the data bank will prove useful to those working on problems associated with the global protection of Earth from collision with near-Earth Objects. These data also can be useful to those involved in developing related to earthquake, volcano, and other such calamitous occurrences. REFERENCES * Andreev,G.V., Goldin,V.D., Vasilyev,N.V., The 1908 Tunguska catastrophe: consequences and prospects for research. Problem of the Earth protection from collision with dangerous near-Earth objects (SPE-94), Theses, part I, 86 - 87, Snezhinsk, 1994. * Cowan C., Atluri C.R. and Libby W.F. Possible anti-matter content of the Tunguska meteor of 1908. Nature, Lond. 206, No 4987, 861 - 865, 1965. * Krinov E.L., Tungusskij meteorit. Izdatelstvo Akademii nauk,Moskva, 1949. * Longo G., Serra R., Cecchini S., and Galli M., Search for microremnants of the Tunguska cosmic body, Planet. Space Sci. 42, 163 - 177, 1994. * Pasechnik, I.,P., Otsenka parametrov vzryva Tungusskogo meteorita po sejsmicheskim i mikrobarograficheskim dannym, In: Kosmicheskoe veshchestvo na Zemle. 24 -25, Nauka, Novosibirsk, 1976. * Plekhanov, G.F., Kovalevsky A.F., Zhuravlyov V.K., Vasilyev N .V., O vlijanii vzryva Tungusskogo meteorita na geomagnitnoe pole, Geologija i geophysika, 6, 94 - 96, 1961. * Vasilyev, N.V., The enigma of century. Science in the USSR 1, 8 - 9, 1985. * Vasilyev, N.V. and Fast N.P., Anomalous optical phenomena caused by Tungus meteorite fall, Gerlands Beitr. zur Geophys., 81, 433 - 438, 1972. * Vorobyev, V.A., The current state of the data set on consequences of the Tunguska catastrophe and possible ways for its saving, International Conference "Problems of the Earth protection from collision with dangerous near-Earth objects (SPE-94)". Theses, part II, 18 -20, Snezhinsk, 1994. * Zhuravlyov, V.K., Zigel, F.Yu., Tungusskoe divo (The history of investigation of the Tunguska meteorite), Novosibirsk, Tseris, 1994. * Zolotov, A.V., Problema Tungusskoj katastrofy 1908 g., Nauka i tekhnika, Minsk, 1969. * * International Institute of Cosmic Antropology, prosp. * Timakova, 2, 630117 Novosibirsk, Russia