title: First known terrestrial impact of a binary asteroid from a main belt breakup event.
abstract: Approximately 470 million years ago one of the largest cosmic catastrophes occurred in our solar system since the accretion of the planets. A 200-km large asteroid was disrupted by a collision in the Main Asteroid Belt, which spawned fragments into Earth crossing orbits. This had tremendous consequences for the meteorite production and cratering rate during several millions of years following the event. The 7.5-km wide Lockne crater, central Sweden, is known to be a member of this family. We here provide evidence that Lockne and its nearby companion, the 0.7-km diameter, contemporaneous, Målingen crater, formed by the impact of a binary, presumably 'rubble pile' asteroid. This newly discovered crater doublet provides a unique reference for impacts by combined, and poorly consolidated projectiles, as well as for the development of binary asteroids.
authors.affiliation: Centro de Astrobiología (INTA-CSIC), Instituto Nacional de Técnica Aeroespacial, Ctra de Torrejón a Ajalvir, km 4, 28850 Torrejón de Ardoz, Madrid, Spain.
authors.forename: Jens
authors.initials: J
authors.lastname: Ormö
authors.affiliation: Department of Earth Sciences, University of Gothenburg, Guldhedsgatan 5 A, 40530 Gothenburg, Sweden.
authors.forename: Erik
authors.initials: E
authors.lastname: Sturkell
authors.affiliation: Dept. of Earth and Ecosystem Sciences, Division of Geology, Lund University, Sölvegatan 12, 223 62 Lund, Sweden.
authors.forename: Carl
authors.initials: C
authors.lastname: Alwmark
authors.affiliation: Earth, Atmospheric, and Planetary Sciences Department, 550 Stadium Mall Drive, Purdue University, West Lafayette, IN 47907-2051, USA.
authors.forename: Jay
authors.initials: J
authors.lastname: Melosh