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

该奖项为建立行星际尘埃吸积的新记录提供了为期两年的资金支持，该记录使用极地冰芯尘埃中的氦-3 （3He）测量。其目的是验证一种假设，即地球10万年的冰期-间冰期气候循环是古气候变化的主要模式，是由地球周围的外星尘埃数量的变化引起的。先前的研究表明，对冰样品中外星3He的测量是准确的、可重复的，并且在分析能力范围内。根据高3He/4He比率和总He预算，来自格陵兰岛和南极冰芯的尘埃样本中几乎所有（98%）的3He都来自地外。根据对最近沉积的冰的测量推断出的外星3He通量与基于其他方法的估计非常吻合。提出的工作的具体目标是比较3He通量的变化与气候变化和基于太阳系地外尘埃分布模型的地外通量的预测变化。由于这是一种新方法，因此还将确定冰芯中含3he的星际尘埃颗粒（IDP's）的最佳样本量要求、尺寸分布和统计数据。这些信息对于IDP的3He积累和获取模型非常重要。

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.