Information that isotopic measurements provide about space and the cosmos

Abstract

The study of the isotopic abundances of the rare gases helium, neon, and argon in iron meteorites lead to the conclusion that the rare gases are produced mainly by the action of the cosmic rays with the meteorites. The high energy cosmic ray particles produce nuclear spallation reactions with the elements composing the meteorites. By comparing the cosmic-ray produced radioactive isotopes of different half lives such as H/sup 3/, Ar/sup 37/, Ar/sup 39/, Cl/sup 36/, Al/su p 26/, Be/sup 10/, and K/sup 40/ it is possible to investigate the constancy of cosmic rays in time and space. The measurements indicate that during the last 500,000 years there was no greater than a 10% change in the intensity of cosmic rays, and that cosmic rays near the earth have about the same intensity as cosmic rays in the asteroidal belt some 450 million kilometers further from the sun. In addition there is evidence that indicates that some of the meteorites have undergone collisions in space previous to being captured by the earth. (auth)