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

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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.