The Sikhote-Alin meteorite shower at 10:30 a.m. 12 February 1947 is the largest known such shower and among the best documented meteorite falls. Yet much of the documentation that continues to appear in articles and books is dated and, consequently, in error.
Later in this update I will describe my recent revisit to this fascinating and meteorite-rich site. I was privileged to become the first foreigner ever to visit the Sikhote-Alin site, according to Valentin Tsvetkov, the world's leading authority on the S-A site and a member of the Russian Academy of Sciences' Astronomical Society. I had met Tsvetkov in Moscow in 1992 on my way to take part in the third international Tunguska expedition. Since 1967 he has developed a number of methodologies that have provided significant new details about the meteorite fall.
The cosmic intruder on that clear cold morning streaked across the blue Siberian sky as a monster bolide that plunged into the atmosphere from NNE to SSW at an angle of about 45 degrees. Trailing a dark dust tail some 35 km long, at an altitude of about 4.5 km it broke up as a swarm of tiny fireballs that disappeared behind the foothills of the Sikhote-Alin mountain range about midway between Vladivostok and Khabarovsk. Eyewitnesses said the bolide was brighter than the Sun, and it was observed over an area 300 to 400 km in radius. They also reported that a few minutes after the fireball first appeared they heard thunderous roars like those from heavy-caliber guns echoing among the mountain ridges.
Korney Shvets, one eyewitness I interviewed in the village of Meteority during my September 1995 visit to the site, said "I saw blue flame sparkling in the sky because the meteorite was burning, and there were little fires trailing behind the main body. The windows of the bakery where I was working with my mother and brother trembled. A metal door of the oven flew open, and several hot charcoals fell out onto the floor. I was only 17 at the time, and I was scared because we thought it was an atomic bomb from the Americans. It was soon after the bomb fell on Hiroshima."
Unlike the Tunguska event, the S-A meteorite shower is well understood, including its orbital elements as most recently calculated by V. I. Tsvetkov. According to Tsvetkov, this makes the S-A meteorite fall the world's first example of orbit calculation by analysis of the dispersion zone of impacting fragments.
It took investigators 19 years to launch the first expedition to the Tunguska site in 1927. But only three days after the S-A strike, pilots spotted the fall site marked by a group of bright auburn patches in the snow-covered taiga. This revealed two important features of the fallit was crater-forming, and it was multiple. Two months later a team of investigators led by the well-known astronomer V. G. Fesenkov hacked their way through the nearly impenetrable taiga to the crater field. They located 122 craters, the largest of which and first to be investigated was 28 meters in diameter and 6 meters deep. Additionally they counted 78 "pits." Four years later more than 20 tons of iron-nickel fragments were in the Soviet Academy of Sciences warehouse.
E. L. Krinov, the leader of later expeditions in which Tsvetkov played a major role, concluded that the dispersion zone was 1 by 2 km with a major axis suggesting that the swarm had rained down from NNW to SSE. N. B. Divari disagreed, saying that his more than 180 eyewitness accounts of the smoke trail fixed the entry direction from NNE to SSW. Krinov said that the wind most likely blew the smoke trail off the bolide's true course. Tsvetkov's later work in 1975 was to prove Divari right, yet it is invariably Krinov's dated writings that appear in the English language scientific press. The 1975 expedition also was to cause major areas of conflict between Krinov and Tsvetkov.
Krinov was a tireless investigator and meticulous in his work, to the extent of examining virtually
every square meter of forest floor in his 1 by 2 km dispersion ellipse, mapping every crater position, and the
exact location of meteorite fragments associated with each crater. Tsvetkov described Krinov as being more
keeping with a natural historian characteristic of the late 19th century than as a man well versed in modern science. Toward the end of the 1975 expedition, Tsvetkov suggested to Krinov that he remain with a small group of 10 and, instead of continuing the time-consuming method of examining every square meter of the area they instead examine a grid of 25- by 25-m plots with a distance between plots of 200 m. In this way, Tsvetkov felt that he might get a more inclusive determination of the boundary than Krinov had obtainedand earlier cast in concrete by publication.
Tsvetkov's new search method quickly paid off by indisputably extending the dispersal area some 10 additional km to the NNE, so extending and reorienting the major axis of the crater field. Tsvetkov's work enlarged the dispersion ellipse to 12 by 4 km. During our 1995 three-person expedition, Tsvetkov told me that Krinov tried to explain away Tsvetkov's findings by saying that the meteorites he found outside the Krinov boundary had been driven away by the wind. However, the next day they brought Krinov a 43 kg fragment that could not possibly have been driven off course by wind. It was Tsvetkov's discovery of a significantly larger fall zone that settled once and for all the passionate argument between Divari and Krinov.
Since my return from Siberia I have been asked if there are still meteorites to be found in and around the crater field. Plenty. I also have been asked how to get there, and if it is "legal" to visit the site.
Meteorites were strewn everywhere. To date, more than 9,000 iron meteorites weighing a total of some 28 to 29 tons have been collected. The largest weighs 1,745 kg, the smallest less than a gram. In addition there is an abundance of microdispersed products of ablation mixed into the forest soil.
Sikhote_Alin is classified as a coarsest octahedrite. Krinov had estimated the post atmospheric mass of the meteoroid at some 70 tons. A more recent estimate by Tsvetkov (and others) puts the mass at around 100 tons. Fesenkov had estimated the meteoroid's velocity on entering the atmosphere at 14.5 km/sec. More recent calculations by Tsvetkov put the entry velocity at 12.4 km/sec.
My 1995 Expedition
Early in the summer Tsvetkov, as a member of the Astronomical Society of the Russian Academy of Sciences, invited me to the S-A site. My interpreter, who had worked with me at the Tunguska site, and I flew into Vladivostok and were met by Tsvetkov, who had flown in a day earlier from Moscow. We spent the next day buying last minute supplies then caught the one a.m. Trans-Siberian train northward to Dalnerechensk, where we arrived at 9:30 a.m.
We were loaded down with three heavy backpacks and one large duffle bag. Tsvetkov managed to find someone willing to drive us the 90 km to the village of Meteority on the edge of the taiga and about 10 km from the 1947 base camp in the middle of the crater field. Forty-five dollars paid the bill. In Russia there is a saying "We have no roads, only directions." The road to Meteority didn't even have directions! The driver said the only sensible way to negotiate it was by helicopter. Two hours later brought us to the small logging village, and then a few kilometers more to the village of Ismailikha, another logging town with a population of 350. The streets of dirt had meandering barriers of pigs, ducks, and cows.
We stayed overnight with Tsvetkov's friend and forest ranger for the region, Alexander, who makes it his business to know about outsiders who visit the area. Up at 8 a.m., selectively repacked, and at 10 a.m. climbed up into a Zil-131 six-wheel military vehicle which I became convinced could cruise over virtually any landscape. After about an hour and a half of fording streams, crashing through, bouncing over, and otherwise assaulting the densest forest imaginable, while churning through water-filled, knee-deep ruts of mud, and throughly shaken, we abruptly stopped at the old 1947 base camp site.
We were greeted by a Russian man and woman who were startled to see us. The night before,
Alexander had told us that "a party of seven meteorite pirates" was at the site and had been there for three weeks.
The woman cook quickly began banging on an anvil which resounded through the forest. One by one, the
other "pirates" appeared and eyed us silently and suspiciously. On learning Tsvetkov's identity, they suddenly
were all respect and smiles. They were academicians from Moscow University moonlighting, they said, to
supplement their meager salaries. That evening over vodka and borscht they told us they had requested
permission to visit the site from the Committee on Meteorites of the Russian Academy of Sciences, promising to
turn over half of what they recovered to the Academy's collection. Director Sukulukov had denied them
sion. They went anyway.
I was stunned to see by their mess tent a large table strewn with more than a hundred meteorites, the morning's take. The largest one weighed in at about 45 kg. Serge, one of the "pirates," said that a few hours with a metal detector can reap up to 10 kg of meteorites. I began to calculate, three weeks of hard work per man equals 210 kg times 5 men equals 1,050 kg. And they were going to be there for three more weeks for a possible total of some 2,000 kg of metal pirated out of the area with no documentation whatever. Tsvetkov was visibly disturbed.
What were they going to do with the meteorites? Tsvetkov asked the leader a few days later. Sell them to "a few companies" that work the international market in meteorites. No names or addresses were forthcoming. "They should be recording the location and mass of every meteorite they remove," Tsvetkov admonished. "That information is important for many reasons an improved estimate of the original object's mass and more details about the object's breakup in the atmosphere."
It was raining when we arrived at the campsite, and it was pouring as we constructed base platforms for our tents. By the time we were set up, clothing, sleeping bags, everything was damp, and my video camera and two Nikons had collected condensation. For the next few days the "pirates" went their way wielding their cumbersome military metal detectors, and we went ours. We climbed down into several craters, all still very much in evidence with their rims of rock rubble but very much overgrown with saplings, vines, and other vegetation. Katya, my interpreter, worked my metal detector with ease, and productively, while I used my global position system (GPS) device to make position plots of some of the larger craters so that Tsvetkov could check the old coordinates made earlier.
I had brought the metal detector along as a gift for Tsvetkov, and his broad grin on accepting it showed his gratitude. My interests were photographing, videotaping, and position plotting.
The area is extraordinarily diverse in flora and fauna. There are Manchurian chestnut trees, Mongolian oak, birches, fir trees, daurian larch, spruce three species of maple, aspen, bird cherry trees with thorns, several types of orchids, and tough lianas the size of small rope that trip you up at nearly every step. Also zsen-sen roots used as a medicinal potion. Among the animals in the area are 250 Siberian tigers, wild boars, and numerous Siberian brown bears that leave footprints the size of a large dinner plate, two species of poisonous snakes, and some nasty plants similar to poison ivy.
The craters are numbered from 1 upward according to size, the higher numbered craters being the smaller ones. Despite its size of only 1.5 m, Crater Number 65 interested me because it involved another dispute between Krinov and Tsvetkov. The 1947 expedition had found a 40-kg meteorite in the crater. Years later Krinov told Tsvetkov that the meteorite had obviously formed the crater. But by that time Tsvetkov had investigated many craters and had established that there was a direct correlation between crater size and meteorite mass. When he checked his graph for Krinov's 40-kg meteorite he found that it fell way off the curve. He told Krinov that a more massive meteorite had to have made the crater. Krinov disagreed, expressing his suspicion of Tsvetkov's mathematical modeling. Then on the 1972 expedition, a team using a magnetometer detected a larger mass buried beneath the crater floor, one weighing 160 kg. It fell neatly on the curve of Tsvetkov's mass/crater-size diagram. Krinov reluctantly admitted that the larger-mass meteorite had probably made the crater and that the smaller-mass object had impacted afterwards. Nevertheless, Krinov continued to mistrust Tsvetkov's mathematical modeling of the crater field, especially of his application of probability theory, which Krinov referred to as the "theory of wonders."
Fragments and Individuals
There are two classes of S-A meteorites. The most common are called "fragments" and litter the major crater field just a few centimeters in the soil. They are the result of relatively large-mass objects shattering on impact with the frozen ground. So many fragments have been removed by Russian and Estonian "pirates" that they flood the international market and can be obtained for small change. Tsvetkov reported that one Estonian collector had brought bucket loads of fragments to his Moscow office.
But there is a second, and more valuable class, and these are harder to come by. Called
"individuals," they are pieces that did not shatter on impact. Due to atmospheric heating and resulting ablation,
individuals developed smooth indentations, or regmaglypts. The individuals were unprecedented, since no museum in the world had such samples in their collections, Tsvetkov told me. To this day, collectors are eager to acquire individuals.
Our next to last day at the site was the most interesting, and strenuous. The three of us slipped out of camp so as not to be followed by any of the others. Tsvetkov said that he was taking us to an area where lots of individuals could be found. It turned out to be a trail-less four-hour hike through dense taiga, swamps and bogs complete with poisonous snakes, and across a small but swift river to a remote mountainside rich with individuals. It was a trip I have repeatedly told myself I would never undertake again. My guess is that there are fewer than a half dozen people alive who could find their way to the site. One hour on the hillside resulted in the recovery of five lovely specimens of individuals.
When I asked Tsvetkov if he currently has plans to lead any more "official" expeditions to further study the S-A site, he said that like everything else in Russia today the situation is very complex and discouraging. First of all, who is guardian of the site? The Committee on Meteorites claims that it is, but local officials in the district say they have the authority to regulate traffic into the site. So where does one apply for permission to visit the site? "Sometimes it is better not to ask," advised Tsvetkov. He said that anyone wanting permission should apply to the Administration of Promrye, a political district of the Russian Far East. The Administration can issue an invitation to visit the site, but only with approval of the Russian Academy of Sciences. All applicants should be prepared to find themselves involved in a Catch-22 situation. My invitation had come verbally from Tsvetkov and in writing from an influential geologist in St. Petersburg.
How can you as a collector obtain specimens of individuals? Find them on the international market, or less likely on the illegal Russian market. But Tsvetkov said that virtually all of the S-A meteorites obtainable in Russia are fragments. What few individuals may be available bring whatever price the owner can manage to get. With a shrug, Tsvetkov said "maybe up to eight dollars a gram."
The original Russian collection is controlled by the Committee on Meteorites, which will not sell specimens. It will lend specimens to research institutions or swap specimens with Museums or scientific organizations. In rare instances the Committee has released specimens as gifts.
Future "Official Expeditions"?
In 1994 Tsvet-kov composed a letter signed by the chairman of the Astronomical Society asking the bureaucratic Committee on Meteorites to authorize for 1997 a 50-year international commemorative expedition, which Tsvetkov volunteered to organize and lead. He listed for the committee chairman, Mr. Sukulukov, several ways in which such an international effort would lead to further understanding of the S-A event and other meteorite falls and would be paid for entirely by foreign participants.
On the 19th of May 1994 came this reply, which in part said:
Dear Dr. Tsvetkov,
Details of the Sikhote-Alin meteorite site have already been exhaustively studied, and there is no need to further study the event. Further, I find it highly doubtful that your proposed expedition could contribute any new scientific data on the problem of the Sikhote-Alin meteorite. It is also doubtful that the study of microdispersed matter would contribute to further understanding of the event. Further, removal of S-A meteorites by foreigners decreases the opportunity [of the Committee on Meteorites] to exchange samples with scientists who have meteorites from other sites. In response to transferring part of the recovered fragments to the Russian Academy of Science, there is no need since the Academy already has enough recovered samples, and they are well studied. We further think that all future visits to the site should be restricted.
Does this scientifically unsound decision mean that the remaining 70 tons of S-A meteorites, oxidizing away in the ground, will never see the light of day? No. There will always be the pirates.
© Copyright Pallasite Press 1996