Collaborative Research: Experimental Investigation of Micrometeoroid Ablation

在这个项目中，一个旨在测量代表行星际尘埃粒子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，以解释地球大气中流星头回波的雷达测量结果，这些回波是由烧蚀产生的。大部分的实验室工作利用了科罗拉多大学的尘埃加速器设备，由美国宇航局资助。美国国家科学基金会的项目将重点解释在Poker Flat、AK、Arecibo、PR、Jicamarca、秘鲁以及阿根廷、日本和挪威等地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，其峰值在85至95公里之间，宽度约为20公里，是由星际尘埃粒子的日常烧蚀产生的。一旦大气中的金属被注入到地球的高层大气中，除了形成金属原子和离子层之外，它们还造成了一系列的现象，比如夜光云的成核；对平流层气溶胶和臭氧化学的影响；用生物可利用的铁给海洋施肥。目前对在上层大气中被烧蚀的微流星体输入的总质量的估计相差两个数量级。准确测定总入射质量，对于确定中大气和地表的垂直输送，以及我们对太阳系尘埃演化的认识都有重要意义。微流星的雷达探测是一种广泛使用的约束质量输入的技术。科罗拉多大学承担的实验室工作将提供对解释这些测量结果所需的关键参数的改进测量：进入大气时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.