Letter to the Editor

The Carancas meteorite impact – Encounter with a monolithic meteoroid

Astronomical Institute of the Academy of Sciences, Fričova 298, 25165 Ondřejov Observatory, Czech Republic e-mail: borovic@asu.cas.cz

Received: 4 April 2008
Accepted: 4 May 2008

Abstract

The formation of a 13-m wide impact crater by a stony meteorite near Carancas, Peru, on September 15, 2007 was an unexpected event. Stony meteoroids usually disintegrate in the atmosphere in many pieces, each landing at low velocity. We present examples of well-observed fireballs, which have all experienced atmospheric fragmentation. Using a simple model, we find that the Carancas meteoroid may have avoided fragmentation, if its strength was 20-40 MPa; such a strength would be comparable to the tensile strength of stony meteorites, but is higher than the strength of other observed meteoroids. We conclude that Carancas was a rare example of a monolithic meteoroid that was free of internal cracks. This example demonstrates that meteoroid strength can vary significantly from case to case and does not depend on meteoroid size. We estimate that the initial size of Carancas meteoroid was 0.9-1.7 m. Our model predicts an impact velocity that was in the range 2-4 km s^-1.