ABSTRACT More than 40,000 tons of interplanetary dust particles fall to the Earth's surface each year. Those particles less than 30 micrometers in size retain to a large extent their extraterrestrial isotopic signature. In the central equatorial Pacific Ocean, a limited geographic region of the earth's surface, the flux of extraterrestrial helium, determined by normalization to thorium-230, has been relatively constant through the past 200 thousand years. In this research, investigators from the Lamont-Doherty Geological Observatory and Tulane University will carry out a thorough investigation of the apatial and temporal variability of the He-3 supply to the sediments throughout the world ocean. Other applications and limitations of extraterrestrial He-3 as a constant-flux proxy will also be explored.
