FOR 887:  Experimental Impact Cratering - The MEMIN-Programme (Multidisciplinary Experimental and Modelling Impact Research Network)

• Subject Area: Geosciences
• Term: from 2009 to 2019
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 35715273

The collision of solid bodies has been and still is one of the fundamental geological processes in our solar system. Understanding highly dynamic impact processes requires interdisciplinary research that includes studies of natural craters, laboratory experiments and numerical simulations. In this general context a multidisciplinary experimental and modelling impact research network (MEMIN) was established comprising geoscientists, physicists and engineers.
Central to the Research Unit are newly designed accelerators, so called two-stage light gas guns that are capable of achieving high impact velocities (5-10 km/s) and energies. With these guns craters can be produced in the decimetre-range in solid rocks, a size previously not achieved at the laboratory scale that will allow detailed spatial analyses. The proposed cratering experiments on sandstone targets comprise a parametric study of the role of water, porosity, target layering and impact velocity on cratering mechanics, shock effects and the distribution of the projectile (the meteorite) during cratering. Seven subprojects will focus on different aspects of the work programme, including (1) complete mineralogical-petrophysical and mechanical characterisation of the target prior to and after the experiment using, for example, state-of-the-art geophysical tools for mesoscale, non-destructive tomography and microstructural analyses of deformation at the micro- and nanoscale; (2) stringent control of the impact experiment itself with newly developed in-situ real-time measurements of fracture propagation, stresses, crater growth and ejecta dynamics; (3) numerical modelling of the complete cratering process.
The Research Unit is designed to yield a solid data base for validation and refining of numerical cratering models that will allow scaling of mesoscale observations to the size of natural craters. It will further our understanding of impact-induced damaging of rocks and, hence, the nature of geophysical signatures of terrestrial craters.

• DFG Programme: Research Units
• International Connection: France, Russia, USA

Projects

• Compaction, strength reduction, and stress estimates in shocked porous sandstones (Applicants Dresen, Georg ;  Kenkmann, Thomas )
• Crater structure and excavation: the effect of lithology and target layering on crater formation in experimental and natural impact craters (Applicants Deutsch, Alexander Gustav Josef ;  Kenkmann, Thomas )
• Dynamic loading and unloading of SiO2 aggregates. Real-time phase transformation monitored by means of synchrotron beam diffraction (Applicant Kenkmann, Thomas )
• Experimental Impact Cratering: The MEMIN II Program (Multidisciplinary Experimental and Modeling Impact Research Network) (Applicant Kenkmann, Thomas )
• Geophysics of cratering experiments: The laboratory perspective (Applicant Große, Christian )
• Investigation of the transient early-stage physical processes of hypervelocity impacts into solid target rocks (Applicant Thoma, Klaus )
• Microscale shock processes in sandstone (Applicants Langenhorst, Falko ;  Reimold, Wolf Uwe )
• Numerical modeling of impact cratering processes (Applicants Sauer, Martin ;  Wünnemann, Kai )
• Projectile-target interaction, melting and vaporization in hypervelocity experiments and natural impactites (Applicants Deutsch, Alexander Gustav Josef ;  Hecht, Lutz ;  Schäfer, Frank )
• Structure and formation of shatter cones in experimental and natural impact craters (Applicants Kenkmann, Thomas ;  Langenhorst, Falko ;  Wünnemann, Kai )

• Spokesperson: Professor Dr. Thomas Kenkmann
• Deputies: Professor Dr. Alexander Gustav Josef Deutsch; Professor Dr. Klaus Thoma