The trajectory, structure and origin of the Chelyabinsk asteroidal impactor

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 × 10(12) 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.

Spectral properties of the largest asteroids associated with Taurid Complex

“…This airburst estimated at 500 ± 100 kilotons of TNT could be associated with (86039) 1999 NC43 11 in terms of dynamical parameters (Borovička et al 2013). The most probable origin of the bolide is from the inner belt ν 6 region.…”

A catalog of video records of the 2013 Chelyabinsk superbolide

“…Videos 1-15 are the calibrated videos used for the determination of the bolide trajectory by Borovička et al (2013). Videos 16-29 are the videos calibrated later by our team that will be used for the refinement of the trajectory in a future paper.…”

“…Nevertheless, the skies were nicely clear in most places around the bolide trajectory. In the surroundings of Ufa, the whole bolide (∼350 km A90, page 4 of 35 (Borovička et al 2013). The green star is the landing point of the largest fragment (Popova et al 2013 away) appeared close to the rising Sun and remained mostly unnoticed.…”

“…These videos represent one of the largest citizen-science documentary efforts in modern times of such an unusual and transitory event. The best characterization of the trajectory, velocity, and impactor orbit were obtained using selected calibrated casual video recordings showing the bolide in flight (Borovička et al 2013;Popova et al 2013). Other videos documented the dust trail in the atmosphere, the arrivals of the blast waves, and the damage to buildings Popova et al 2013).…”

“…In our previous work (Borovička et al 2013) we used in situ stellar calibration, i.e. determination of the alt-azimuthal coordinate system, of 15 videos.…”