Hypervelocity collisions within the solar system represent a primary process in the accretion and modification of planetary bodies. A record of impact processes on meteorite parent bodies is contained in the shock metamorphic effects. We have used shock effects in L chondrites to estimate the pressure and duration of shock events to understand the impact the impact history of the L-chondrite parent body. Impact calculations suggest that the S6 L6 chondrites were derived from deep in the parent body. Several important questions remain: 1) What happened to chondritic material that was shocked to extreme pressures and how do these transition into impact melt rocks? 2) Are shock effects and impact histories of other parent bodies similar to those of L chondrites? 3) What shock effects would we expect from collisions early in the history of the solar system, when parent bodies were hot enough for continued metamorphism? We will address these questions by applying our expertise from studying highly shock (S4-S6) L chondrites to a carefully selected set of L, LL, H, CK chondrites and SNCs. All samples will have shock veins or documented shock effects. We will study samples that have been Ar-Ar dated when possible so that we can correlate our shock and impact results with impact history and dynamics in the asteroid belt. We will use a combination of optical microscopy, Raman spectroscopy, scanning electron microscopy and micro X-ray diffraction to characterize shock effects, high-pressure minerals and microstructures associated with shock veins. We will use focused ion beam and transmission electron to investigate the nano-structures of these materials to constrain formation mechanisms and shock conditions. Finally, we will use shock physics and Autodyne hydrocode calculations to explore the range of impact scenarios that are consistent with the shock pressure and duration inferred from the samples. This research will allow us to extend our understanding of shock in L chondrites to other parent bodies that were shocked earlier in the history of the solar system. It will also allow us to better understand a broader range of shock effects in meteorites so that others can more accurately interpret parent body processes in all meteorites.
|Effective start/end date||6/13/13 → 6/12/17|
- NASA: Goddard Space Flight Center: $309,000.00