Collaborative Research: Experimental Investigation of Micrometeoroid Ablation

在这个项目中，一项旨在测量代表行星际尘埃颗粒的粒子的蒸发速率和电离效率的实验室研究将与模型相结合，以解释对地球大气中由消融产生的流星头回波的雷达测量。大部分实验室工作利用了科罗拉多大学的尘埃加速器设施，由美国国家航空航天局资助。NSF项目将专注于解释在Poker Flat、AK、阿雷西博、PR、Jicamara、秘鲁以及阿根廷、日本和挪威的雷达上进行的流星雷达测量。NSF将支持实验室结果、建模和雷达数据解释之间的协调，以及本科生参与实验室测量。中性金属原子层，如Fe，Mg，Ca，K和Na，峰值在85到95公里之间，宽度约20公里，是由星际尘埃粒子每天烧蚀产生的。一旦将陨石金属注入地球上层大气层，除了金属原子和离子层的形成外，还会造成一系列现象，例如夜光云成核；对平流层气溶胶和臭氧化学的影响；以及利用生物可利用的铁使海洋肥沃。目前对上层大气中被烧毁的微流星体输入总质量的估计相差两个数量级。准确确定总入射质量对于确定大气中部和地表的垂直输送，以及我们对太阳系尘埃演化的理解都是相关的。雷达探测微流星是一种广泛使用的限制质量输入的技术。科罗拉多大学进行的实验室工作将大大改进对解释这些测量所需的关键参数的测量：进入大气层后的消融过程中的电离效率。

In this project, a laboratory a study aimed at measuring the evaporation rate and ionization efficiency of particles representing interplanetary dust particles will be combined with models to interpret radar measurements of meteor head echoes in the Earth's atmosphere, which are generated by ablation. Much of the laboratory work, which utilizes a dust accelerator facility at the U. of Colorado, is being funded by NASA. The NSF project will focus on interpreting meteor radar measurements performed at sites including Poker Flat, AK, Arecibo, PR, Jicamarca, Peru, and radars in Argentina, Japan and Norway. NSF will support the coordination between the laboratory results, modeling, and radar data interpretation, as well as undergraduate student participation in the laboratory measurements.Layers of neutral metal atoms, such as Fe, Mg, Ca, K and Na, which peak between 85 and 95 km and are ~20 km in width, are produced by the daily ablation of Interplanetary Dust Particles. Once the meteoric metals are injected into the Earth's upper atmosphere they are responsible for a range of phenomena in addition to the formation of layers of metal atoms and ions, such as nucleation of noctilucent clouds; impacts on stratospheric aerosols and ozone chemistry; and fertilization of the ocean with bio-available iron. Current estimates for the total mass of the micrometeoroid input that is ablated in the upper atmosphere vary by two orders of magnitude. The accurate determination of the total incoming mass is relevant to determining vertical transport in the middle atmosphere and to the surface, and our understanding of dust evolution in the solar system. Radar detection of micrometeors is a widely used technique to constrain the mass input. The laboratory work undertaken by the U. of Colorado will provide much improved measurements of the key parameter needed to interpret these measurements: the ionization efficiency during the ablation process upon atmospheric entry.