Research led by PSI’s Vishnu Reddy on the Chelyabinsk meteorite that disintegrated over Russia in February 2013 has put to rest a long-standing debate about the source of the asteroid that impacted the Earth and caused the extinction of the dinosaurs.
Astronomers have debated whether the dinosaur killer was linked to the breakup of a large asteroid forming the Baptistina Asteroid Family (BAF) beyond Mars, some of which ended up on Earth-crossing orbits. The asteroid impacting Earth is thought to have been dark and carbonaceous. The BAF hypothesis was bolstered by them being dark and with a spectral shape similar to carbonaceous meteorites.
Analysis of the Chelyabinsk meteorite shows that shock produced during catastrophic disruption of a large asteroid can darken otherwise bright silicate material. Shock darkening was first reported by Dan Britt (now at the University of Central Florida) in the early 1990s. The Chelyabinsk meteorite has both bright unshocked and dark shocked material. However, the details of the spectra of the dark Chelyabinsk material closely reproduces spectral signatures seen with members of the Baptistina Asteroid Family, Reddy said. The findings are in the paper “Chelyabinsk meteorite explains unusual spectral properties of Baptistina Asteroid Family” that appears in Icarus.
Above, a slice of the Chelyabinsk meteorite shows the bright unshocked LL chondrite material and the shock darkened impact melt material.
