Improved Meteoroid Characterization through Laboratory Experiments, Modeling, and Ground-based Observations

通过实验室实验、建模和地面观测改进流星体表征

• 批准号: 1833209
• 负责人: Robert Marshall
• 金额: $ 64.51万
• 依托单位: University of Colorado at Boulder
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2018
• 资助国家: 美国
• 起止时间: 2018-09-01 至 2023-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1833209&HistoricalAwards=false
• 关键词: Improved; Meteoroid; Characterization; through; Laboratory

A four-year research designs to investigate and improve the understanding of the relationship between the properties of a meteoroid and the resulting mesosphere and lower thermosphere (MLT) meteor optical emission and radar signatures. Laboratory experiments would be set up to simulate the ablation of meteors by the Earth's atmosphere by firing projectiles with known mass, speed, and composition into a laboratory chamber containing a known density of gas. The observed relationship found between the luminous brightness of the simulated meteor with the mass of the projectile used would help enable the use of ground-based radar and optical meteor measurements to determine the masses of individual meteoroids with considerably improved accuracy. This result would then quantify the estimate of the total meteor influx of objects into the Earth's atmosphere. This research would be done through experiments at the University of Colorado's Institute for Modeling Plasma, Atmospheres and Cosmic dusT (IMPACT) facility in which the goal would be the recreation of the ablation process in well-defined laboratory conditions. These experimental results would then be applied to meteor observational data derived from both radar and optical techniques, in order to estimate masses of individual meteor events and to validate experimental and modeling results. This award would further support the education and training of a graduate student pursuing a Ph.D at CU Boulder. In addition, undergraduate students would be involved in the program through the Discovery Learning Apprenticeship Program (DLAP) at CU Boulder. The DLAP program provides CU undergraduates a hands-on research experience, with pay, culminating in a final research report and a presentation to faculty and graduate students in the program. Finally, results from the research would be integrated into a new undergraduate course entitled 'Space: Environment and Effects', to begin in Fall 2018. This course is being developed under the auspices of a campus wide "Space Minor" open to students in all majors; as such, this curriculum would reach students beyond science and engineering. Meteors make up a key component of the space environment, and so this research would be used as a key topic to underline the fascinating complexity of the near-earth space environment. The researcher plans to include lectures on simulated meteor work in this series.Meteoroids enter the Earth's atmosphere with velocities between 10 and 70 km/s and masses from femtograms (fg) up to grams or larger; however, the total mass flux of meteoroids remains uncertain, with a range of estimates spanning two orders of magnitude. The ablation of meteoroids are suggested to be responsible for the creation of metal layers of the upper atmosphere, including atomic iron (Fe), magnesium (Mg), calcium (Ca), potassium (K), and sodium (Na) layers that all peak within the range of 85-95 km altitude. These metal layers lead into a variety of aeronomical phenomena, including the nucleation of noctilucent cloud particles, ocean fertilization with bio-available Fe, and creating a relationship between stratospheric aerosol content and O3 chemistry. Moreover, meteors of milligram size and larger pose a risk to spacecraft orbiting the Earth, with the potential to cause physical or electrical damage. Accurate assessment of the total mass flux is critical to improving the understanding of each of these areas. The total mass flux error is primarily caused by the inability to determine masses of individually observed particles. The major sources of uncertainty that lead to poor estimates of meteoroid masses are uncertainty in the parameters which map the mass to observables, such as optical emissions and radar cross section. These parameters are the luminous efficiency and the ionization probability. The project would possibly provide the best measurements to date for a range of velocities and for different materials representative of meteoroids. The foremost science objective in this award addresses a simple yet critical problem in understanding MLT aeronomy: what is the total mass flux entering our atmosphere from space? The ability to create artificial meteors in the lab provides a great opportunity to engage with the community in a way that non-specialists can understand.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.

一项为期四年的研究旨在调查和增进对流星体特性与由此产生的中间层和低热层（MLT）流星光发射和雷达特征之间关系的理解。实验室实验将通过向含有已知气体密度的实验室室发射已知质量、速度和成分的射弹来模拟地球大气层对流星的烧蚀。观察到的模拟流星的发光亮度与所用射弹质量之间的关系将有助于使用地面雷达和光学流星测量来确定单个流星体的质量，并大大提高准确性。然后，该结果将量化流入地球大气层的流星总数的估计。这项研究将通过科罗拉多大学等离子体、大气和宇宙尘埃建模研究所 (IMPACT) 设施的实验来完成，其目标是在明确的实验室条件下重现消融过程。然后，这些实验结果将应用于从雷达和光学技术获得的流星观测数据，以估计单个流星事件的质量并验证实验和建模结果。该奖项将进一步支持在科罗拉多大学博尔德分校攻读博士学位的研究生的教育和培训。此外，本科生将通过科罗拉多大学博尔德分校的发现学习学徒计划 (DLAP) 参与该计划。 DLAP 项目为 CU 本科生提供带薪实践研究经验，最终形成最终研究报告并向该项目的教师和研究生进行演示。最后，研究结果将被纳入一门新的本科课程，题为“空间：环境与影响”，将于 2018 年秋季开始。该课程是在校园范围内的“空间辅修课程”的支持下开发的，向所有学生开放专业；因此，该课程将覆盖科学和工程以外的学生。流星是太空环境的关键组成部分，因此这项研究将作为一个关键主题来强调近地太空环境令人着迷的复杂性。研究人员计划在本系列中包括有关模拟流星工作的讲座。流星体以 10 至 70 公里/秒的速度进入地球大气层，质量从飞克 (fg) 到克或更大；然而，流星体的总质量通量仍然不确定，估计范围跨越两个数量级。流星体的烧蚀被认为是高层大气金属层形成的原因，包括原子铁 (Fe)、镁 (Mg)、钙 (Ca)、钾 (K) 和钠 (Na) 层，高峰在海拔85-95公里范围内。这些金属层导致了各种航空现象，包括夜光云颗粒的成核、生物可利用的铁对海洋的施肥，以及在平流层气溶胶含量与 O3 化学之间建立关系。此外，毫克级或更大的流星对绕地球运行的航天器构成风险，有可能造成物理或电气损坏。准确评估总质量通量对于增进对每个领域的理解至关重要。总质量通量误差主要是由于无法确定单独观察到的粒子的质量引起的。导致流星体质量估计不佳的不确定性主要来源是将质量映射到可观测值的参数的不确定性，例如光发射和雷达截面。这些参数是发光效率和电离概率。该项目可能会提供迄今为止对一系列速度和代表流星体的不同材料的最佳测量。该奖项最重要的科学目标解决了理解 MLT 航空学时一个简单但关键的问题：从太空进入大气层的总质量通量是多少？在实验室中制造人造流星的能力提供了一个以非专业人士可以理解的方式与社区互动的绝佳机会。该奖项反映了 NSF 的法定使命，并通过使用基金会的智力优势和更广泛的评估进行评估，被认为值得支持。影响审查标准。

项目成果

Experimentally Derived Luminous Efficiencies for Aluminum and Iron at Meteoric Speeds

实验得出铝和铁在极快速度下的发光效率

• DOI: 10.1029/2023gl103016
• 发表时间: 2023-04
• 期刊: Geophysical Research Letters
• 影响因子: 5.2
• 作者: Tarnecki, L. K.;Marshall, R. A.;Fontanese, J.;Sternovsky, Z.;Munsat, T.
• 通讯作者: Munsat, T.