Collaborative Research: Accretion of Interplanetary Dust: A New Record from 3He in Polar Ice Cores

Brook/9909384 Kurz/9909663该奖项提供了两年的资金支持，用于使用极地冰芯尘埃中的氦-3（3 He）测量来构建行星际尘埃吸积的新记录。 其目的是检验地球10万年的冰川-间冰期气候循环是古气候变化的一种主要模式，是由地球周围的外星尘埃数量的变化引起的假设。 以前的工作表明，冰样品中的外星3 He测量是准确的，可重复的，并且在分析能力范围内。 事实上，所有（98%）的3 He从格陵兰岛和南极冰芯的尘埃样本是外星人，基于高3 He/4 He比和总的He预算。 推断的地外3 He通量，从测量最近沉积的冰，同意与其他方法的基础上估计。 拟议工作的具体目标是比较3 He通量的变化与气候变化和根据太阳系中的地外尘埃分布模型预测的地外通量变化。 因为这是一种新的方法，最佳的样本量要求，大小分布，并在冰芯中的3 He轴承行星际尘埃粒子（IDP）的统计数据也将被确定。 这一信息将是重要的3 He吸积和收购IDP的模型。

Brook/9909384Kurz/9909663This award provides support for two years of funding to construct a new record of interplanetary dust accretion, using Helium-3 (3He) measurements in polar ice core dust. The objective is to test the hypothesis that the earth's 100,000 year, glacial-interglacial climate cycle, a major mode of paleoclimate variability, is caused by variations in the amount of extraterrestrial dust surrounding the earth. Previous work has shown that measurements of extraterrestrial 3He in ice samples are accurate, reproducible, and well within analytical capabilities. Virtually all ( 98%) of the 3He in dust sample from Greenland and Antarctic ice cores is extraterrestrial, based on high 3He/4He ratios and total He budgets. The inferred extraterrestrial 3He flux, from measurements in recently deposited ice, agrees well with estimates based on other methods. The specific objective of the proposed work is to compare variations in 3He flux to both climate variations and predicted variations in extraterrestrial flux based from models of extraterrestrial dust distribution in the solar system. Because this is a new approach, optimal sample size requirements, size distribution, and statistics of 3He-bearing interplanetary dust particles (IDP's) in ice cores will also be determined. This information will be important for models of 3He accretion and acquisition by IDP's.