Collaborative Research: Accretion of Interplanetary Dust: A New Record From 3HE in Polar Ice Cores

Brook/9909384 Kurz/9909663该奖项为两年的资金提供支持，以利用极地冰芯尘埃中的氦-3(3He)测量来构建星际尘埃积累的新记录。其目的是验证这样一种假设，即地球10万年的冰川-间冰期气候周期是古气候变化的主要模式，是由地球周围外星尘埃数量的变化引起的。以前的工作已经表明，在冰样中测量地外3He是准确的、可重复性的，并且完全在分析能力范围内。根据高的3He/4He比值和总的氦预算，格陵兰和南极冰芯的尘埃样本中几乎所有(98%)的3He都来自外星。从最近沉积的冰中的测量推断的地外3He通量与基于其他方法的估计很好地一致。这项拟议工作的具体目标是将3He通量的变化与气候变化和根据太阳系地外尘埃分布模型预测的地外通量变化进行比较。由于这是一种新的方法，还将确定冰芯中含3He的星际尘埃粒子(IDP)的最佳样本量要求、大小分布和统计数据。这一信息将对IDP的~3He吸积和获取模型具有重要意义。

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.