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RE: Sterlitamak crater
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 Google earth file: Sterlitamak.kmz (Kmz)



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Title: Meteorite Sterlitamak -- A New Crater Forming Fall
Authors: Petaev, M. I.

The Sterlitamak meteorite fell on May 17, 1990 at 23h20m local time (17h20m GMT) and formed a crater in a field 20 km westward of the town of Sterlitamak (Petaev et al., 1991). Many witnesses in South Bashkiria saw a very bright fireball (up to -5 magnitude) moving from south to north at a ~45 degree angle to the horizon. Witnesses located ~2 km from the crater observed the fireball glowing right up to the time of impact, after which several explosions were heard. The crater was found on May 19. From witnesses' reports, the fresh crater was 4.5-5 m in depth and had sheer walls ~3 m in height below which was a conical talus surface with a hole in the center. The crater itself was surrounded by a continuous rim 60-70 cm in thickness and by radial ejecta. Our field team arrived at the crater on May 23, six days after its formation. We found the crater in rather good condition except for partial collapse of the rim, material from which had filled in the crater up to ~3 m from the surface. The western wall of the crater was composed of well-preserved brown loam with shale- like parting dipping 25-30 degrees away from the crater center. A large slip block of autogenic breccia was observed along the eastern crater wall. An allogenic breccia composed of a mixture of brown loam and black soil was traced to the depth of ~5 m from the surface. Outside the rim, the crater ejecta formed an asymmetric continuous blanket and distinct radial rays. The southern rays were shorter and thicker than the northern and eastern rays. About 2 dozen meteorite fragments, from several grams to several hundred grams in weight, were recovered in the crater vicinity. A search for other meteorite fragments or individuals at distances up to 1 km southward from the crater was unsuccessful. Two partly encrusted fragments (3 and 6 kg) with clear Widmanstatten pattern on a broken surface were found at a depth of ~8 m during crater excavation. In May of 1991 a 315-kg partly fragmented individual was recovered at a depth of ~12 m. This sample is a 50 x 45 x 28 cm block with front, rear and two adjoining lateral surfaces covered by regmaglypts and thick (~0.5 mm) fusion crust. The other two surfaces are very rough, contain no regmaglypts, and have a thinner fusion crust. The preimpact shape of the meteorite may be approximately modeled as a slab ~100 x 100 x 28 cm. An estimate of the projectile mass was made based on the crater dimensions. From the relationships between crater diameter and projectile mass determined for the Sikhote-Alin craters, the impact mass of the Sterlitamak meteorite is estimated at ~1 ton (Petaev, 1992). A separate estimate, based on cratering energy, yields a total mass of ~1.5 tons (Ivanov, Petaev, 1992). A comparison of the estimated projectile mass and the weight and morphology of the individual recovered suggests a fragmentation of the projectile in the atmosphere and the formation of the crater by the impact of an agglomeration of individuals. The other fragments of the projectile are still in the crater. REFERENCES Ivanov B.A., Petaev M.I. (1992) Lunar Planet. Sci. (abstract), 23, 573-574. Petaev M.I. (1992) Astron. Vestnik, #4, in press (in Russian) (English translation is named Solar System Research). Petaev M.I., Kisarev Yu.L., Mustafin Sh.A., Shakurov R.K., Pavlov A.V., Ivanov B.A. (1991) Lunar Planet. Sci. (abstract), 22, 1059-1060

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The Sterlitamak (Iron) meteorite fell in Respublika Bashkortostan, Russia, on the 17th May, 1990.
A total mass of 325 kg was recovered.

53° 40'N, 55° 59'E 



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On the 17 May 1990 at 23:20 local time , a 1000 - 1500kg meteorite, on a 45° angle of approach, impacted the ground forming a crater 20km west of Sterlitamak in Bashkiria.
The crater is 15m of diameter and 4.5 to 5m deep. Unfortunately, image precision is not enough to see such a crater.
The meteorite has been calculated as being a 100x100x28cm iron projectile which reach a -5 magnitude (brighter than Venus) during its entry through the Earths atmosphere. The impact velocity was estimated to be over 2 km/s and impact force was equal to 1 ton of TNT.
The crater formed in a potato field was about 9.4 meter wide and 3 meter deep.
A 300 kg meteorite was recovered from 15 meter below surface.
The main mass is still in the crater; it is estimated that there should be at least one ton deeper in the ground.

55.62405E_53.68597N
Expand (98kb, 802 x 526)
Latitude: 53.68597 Longitude: 55.62405

Title: The Sterlitamak meteorite fall
Authors: Petaev, M. I.; Gareev, E. Z.

The paper describes the characteristics of the Sterlitamak-meteorite-fall event and the meteorite itself, which fell on May 17, 1990 in southern Bashkiriia (USSR), 20 km west of Sterlitamak. Special attention is given to the observations made during the fall of the meteorite, the features of the impact crater, the map of the ejecta, and preliminary results of morphological and chemical analyses. On the basis of these analyses, it is concluded that the Sterlitamak meteorite belongs to the type of medium-structure octahedrites of group III A, the representatives of which are fragments of small planets whose active life was completed about 4 billion years ago.

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