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Sikhote Alin
The largest meteorite shower in historical time
Up to date the Sikote Alin meteorite fall is the largest witnessed
meteorite shower in historical times. It occured in Eastern Siberia on February 12, 1947. "In full daylight a fireball
moved from north to south and, at 10:38 a.m. local time, fragmented in the Earth's atmosphere.
The debris covered an elliptical area of 1.6 square kilometers on the snow covered western spurs of the
Sikhote Alin mountains." (Buchwald 1975).
The Russian scientists Krinow, Fesenkov, Shipulin and Chettjikov collected numerous
eyewitness records from places up to 180km from the fall and provided extensive studies of the event. Due to their efforts
Shikote Alin is one of the best understood meteorite falls in history. The image above shows three specimens from the Buhl Meteorite
Collection of 4.917kg, 261g and 7.910kg weight respectively.
The Russian mineralogist and kosmochemist E.L. Krinow described the field work and gave numerous
photographs of the impact holes, violently damaged trees and of individual fragments collected (Krinow 1959).
In the years from 1947 to 1950 about 8,500 specimens ranging from 1g to 1745kg and totalling more than 23 tons
have beend collected during annual expeditions sent to the impact site by the
Russian Academy of Sciences in Moscow.
The pre atmospheric size of the Sikhote body was estimated to ~1,000 metric tons and
more than 70 tons, including dust, is estimated to have reached the ground.
The image above shows an oriented 261.9g individual,
the image below a 3.7kg specimen in pristine find condition.
The complete break up of the meteorite occured at an altitude of 4-6km. Three
main stages of fragmentation have been determined. The first stage of fragmentation occured while the body
was moving with a significant cosmic velocity. Individuals specimens separated during this event
received the highest ammount of aerodynamic surface shaping. In the second phase of fragmentation
some of the masses separated during stage one, again, fragmented. The cosmic velocity
retained was sufficcient to produce distinct regmaglypts. The last
in flight fragmentation occured when the meteorites had lost almost all of their cosmic velocity. The surfaces
produced during this last stage of fragmentation show angular and irregular rough features
with only little or no "aerodynamic molding" as Krinow calls it.
Shikote Alin specimens produced in the 1st and 2nd fragmentation underwent a sufficient time of individual flight to develop a
distinct pattern of regmalypts. In compact shaped individuals with diamters of the order of tens of centimeters the
size of the regmaglypts usually corresponds to the size of the individual by an average ratio of K=0.09. The
ratio K is inversely proportional to the size of meteorites. Regmaglypts conforming to this ratio, like
on the 4.91kg sample pictured above, are considered normal (Krinow 1974). Considerably larger regmaglypts are usually
representing the orginal surface of a larger mother body that fragmented in the late stage of the flight.
Sikhote Alin documentary
The 17 minute documentary displayed below covers the first three expeditions
sent to the fall site on behalf of the Russian Academy of Sciences in Moscow from 1947 to 1950.
Due to the efforts of Sergey Vasiliev (SV Meteorites) and Jeff Kuyken (meteoritesaustralia) this
unique contemporary document can now be viewed with English subtitles.
Soviet documentary covering expeditions to the fall site from 1947 to 1950.
The image below shows a heavily sculpted 7.910kg mass from the Fersman Mineralogical Museum in Moscow. The specimen displays
several >3.5 cm deep cavities with ragged surfaces on their bottom. They represent the original shear surfaces
resulting from in flight fragmentation. The forming of
regmaglypts reached only two thirds of these cavities with their bottom protected in a dead angle from
the ablative forces of the plasma jet stream.
