Reconstructing the Chelyabinsk event: pre-impact orbital evolution

Abstract

The Chelyabinsk superbolide was the largest known natural object to enter the Earth's atmosphere since the Tunguska event in 1908 and it has become a template to understand, manage and mitigate future impacts. Although the event has been documented in great detail, the actual pre-impact orbit of the parent body is still controversial. Here, we revisit this topic using an improved Monte Carlo approach that includes the coordinates of the impact point to compute the most probable solution for the pre-impact orbit (a = 1.62 au, e = 0.53, i = 3.97 degrees, \Omega; = 326.45 and \omega; = 109.71). We also check all the published solutions using a simple yet robust statistical test to show that many of them have problems to cause an impact at the right time. We use the improved orbit and N-body simulations to revisit the dynamical status of a putative Chelyabinsk asteroid family and confirm that it could be linked to resonant asteroids 2007 BD7 and 2011 EO40. In addition, and as the classification of Chelyabinsk meteorites is well established, a search for meteorite falls of the same chondrite group and petrologic type gives some evidence for the existence of an associated LL5 chondrite cluster.