EAR-PF: Windows into Ancient Impacts: Examining Meteoritics Research with New Approaches

梅丽莎·西姆斯博士获得了美国国家科学基金会EAR博士后奖学金，在约翰霍普金斯大学June Wicks教授和Sabine Stanley教授的指导下，在劳伦斯利弗莫尔国家实验室Minta Akin博士的指导下开展研究和教育活动。研究将集中在了解流星撞击和随后的陨石坑；因为这些过程在地球的形成和演化中发挥了重要作用。Sims博士将在现场x射线衍射和想象技术的帮助下进行一系列10个高压冲击实验，以更好地了解受冲击橄榄石和斜长石的变形机制和相变动力学。这些矿物是地球和其他岩石行星中重要的火成岩矿物。此外，影响过程与国防相关，这是该项目的另一个更广泛的影响。西姆斯博士将在少数民族服务机构指导本科生，在那里她也将作为一个榜样。该项目将使用高压实验来调查埋藏或侵蚀陨石坑形成的条件。这些信息往往在撞击后由于侵蚀或风化而丢失。这一建议的最终目标是产生一个更完整的自然冲击过程的画面。西姆斯博士将在实验时间尺度上研究冲击，并推断在自然时间尺度上可能发生的矿物转化的类型和程度。本项目将完成两类实验，使用金刚石砧细胞的快速压缩实验和使用气枪的冲击实验。最近出现了新的分析工具，可用于原位研究冲击过程。西姆斯博士将应用衍射和散射分析来确定实验过程中发生的变形和相变过程。通过改变实验条件，如峰值压力和温度，就有可能理解自然事件。该研究将在少数民族服务机构的本科生的协助下完成，他们将参与国家实验室设施的实验。该项目获得了地球科学部地球物理学、地球化学和岩石学项目的资助。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Dr. Melissa Sims has been granted an NSF EAR Postdoctoral Fellowship to carry out research and education activities at Johns Hopkins University under the mentorship of Professors June Wicks and Sabine Stanley and at Lawrence Livermore National Laboratory guided by Dr. Minta Akin. The research will focus on understanding meteor impacts and subsequent cratering; as these processes played an important role in the formation and evolution of the Earth. Dr. Sims will conduct a series of 10 high-pressure shock experiments aided by in-situ X-ray diffraction and imagining techniques to better understand of deformation mechanisms and phase transition kinetics in shocked olivine and plagioclase. These minerals are important igneous minerals in the Earth and other rocky planetary bodies. Additionally, impact processes are relevant to national defense, which is another of the broader impacts of this project. Dr. Sims will mentor undergraduate students at minority serving institutions where she will also serve as a role model.The project will use high pressure experiments to investigate the conditions under which buried or eroded craters are formed. This information often lost subsequent to impacts due to erosion or weathering. The ultimate goal of this proposal is to produce a more complete picture of natural shock processes. Dr. Sims will examine shock on experimental timescales and extrapolate the types and extent of mineral transformations which are possible on natural timescales. This project will complete two types of experiments, rapid compression using diamond anvil cells and shock experiments using gas guns. New analytical tools have recently become available to investigate shock processes in-situ. Dr. Sims will apply diffraction and scattering analysis to identify the deformation and phase transformation processes that occur during the experiments. By varying experimental conditions, such as peak pressure and temperature, it is possible to understand natural events. The research will be completed with the assistance of undergraduate students from a minority-serving institution who will be involved with experiments at national laboratory facilities. This project received funding from the Geophysics and the Geochemistry and Petrology programs in the Earth Science division.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.