Nature 503, 235–237 (2013 November 14)
doi:10.1038/nature12671
The trajectory, structure and origin of the Chelyabinsk asteroidal
impactor
Jiri Borovicka1, Pavel Spurny1,
Peter
Brown2,3, Paul Wiegert2,3, Pavel Kalenda4,
David
Clark2,3 & Lukas Shrbeny1
1Astronomical Institute,
Academy of Sciences of the Czech Republic, CZ-25165 Ondrejov, Czech
Republic
2Department of Physics and Astronomy, University of Western
Ontario, London, Ontario N6A3K7, Canada
3Centre for Planetary Science and Exploration, University of
Western Ontario, London, Ontario N6A 5B7, Canada
4Institute of
Rock Structure and Mechanics, Academy of Sciences of the Czech
Republic, V Holesovickach 41, CZ-18209 Praha 8, Czech Republic
Abstract. Earth is continuously colliding with fragments of
asteroids and comets of various sizes. The largest encounter in
historical times occurred over the Tunguska river in Siberia in 1908,
producing an airburst of energy equivalent to 5–15 megatons of
trinitrotoluene (1 kiloton of trinitrotoluene represents an energy of
4.185 ×1012 joules).Until recently, the next most
energetic airburst events occurred over Indonesia in 2009 and near the
Marshall Islands in 1994, both with energies of several tens of
kilotons. Here we report an analysis of selected video records of the
Chelyabinsk superbolide of 15 February 2013, with energy equivalent to
500 kilotons of trinitrotoluene, and details of its atmospheric
passage.We found that its orbit was similar to the orbit of the
two-kilometre-diameter asteroid 86039 (1999 NC43), to a degree of
statistical significance sufficient to suggest that the two were once
part of the same object. The bulk strength—the ability to resist
breakage—of the Chelyabinsk asteroid, of about one megapascal, was
similar to that of smaller meteoroids and corresponds to a heavily
fractured single stone. The asteroid broke into small pieces between
the altitudes of 45 and 30 kilometres, preventing more-serious damage
on the ground. The total mass of surviving fragments larger than 100
grams was lower than expected.
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