Rate of Accretion of Cosmic Dust on the Earth

Abstract

As guest professor of geophysics at the University of Hawaii, I have had opportunities for collecting cosmic dust by filtering large volumes of air through fine-pored filters at Mauna Loa Observatory on Hawaii (11,000 ft.) and from the summit of Mt. Haleakala on Maui (10,000 ft.), localities where the air is generally free from terrestrial dust to a remarkable degree. The filters were analysed for the radioactive fall-out products, strontium-89 and strontium-90, in the laboratories of the U.S. Atomic Energy Commission in New York, and for iron, nickel and cobalt in the II Chemisches Institut der Universität, Vienna. I am indebted to Mr. John H. Harley for the strontium analyses, which will be published elsewhere, and also to Prof. F. Hecht and his collaborator Dr. E. Tomic of Vienna for carrying out the analyses for the ferrides.