DYNAMICS OF THE CHELYABINSK METEOROID FALL: ALTITUDE AND TIME DEPENDENCES

Purpose: Taking the altitude and time dependences of the meteoroid fragment speed, acceleration, mass, and the midsection from the measured trajectory data. Design/methodology/approach: Numerical calculations have been made of the Chelyabinsk celestial body speed, acceleration, mass, and midsection variations with time and altitude. The third order spline fits have been shown to be acceptable. The model results have been compared to the measured optical radiation intensity. Findings: Using the equations of meteorite physics with accounting for the deceleration, gravity and Coriolis forces the regression analysis for fitting the meteoroid altitude and geographic coordinates was made and the dependences of the meteoroid speed, acceleration, mass, and optical radiation intensity on time and altitude found. In all cases, the approximation is performed with cubic splines. The speed has been shown to decrease approximately by a factor of 3 when the altitude decreases from 40 to 15 km over the 03:20:32–03:20:36 UT interval. The average deceleration is equal to –4 km/s2, while the maximum deceleration of –6 km/s2 occurs within the same altitude range. Based on speed vs. time and optical radiation intensity vs. time dependences, the dependences of meteoroid mass vs. time and vs. altitude have been plotted. The most significant change in the mass occurs during the 03:20:32–03:20:33 UT interval and the calculations show a value of 5 kt/s. The air drag coefficient has been estimated from the determined dependences of speed, deceleration, mass loss rate, and meteoroid midsection on time and altitude. Conclusions: The third order splines provide the best fit to the Chelyabinsk meteoroid altitude and geographic coordinate regression time dependences. The temporal dependences of the Chelyabinsk celestial body speed and deceleration have been calculated from the trajectory measurements. The equations of meteorite physics have been used to calculate mass, midsection, and meteoroid optical radiation intensity vs. time and vs. altitude dependences. The air drag coefficient have been presented.