Very Heavy Solar Cosmic Rays: Energy Spectrum and Implications for Lunar Erosion

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Science  26 Mar 1971:
Vol. 171, Issue 3977, pp. 1240-1242
DOI: 10.1126/science.171.3977.1240


The energy spectrum of solar cosmic-ray particles of the iron group has been determined for the first time over the energy range from 1 to 100 million electron volts per nucleon by the use of glass removed from the Surveyor 3 spacecraft. The difference between the observed (energy)-3 spectrum and the limiting spectrum derived previously from tracks in lunar rocks gives an erosion rate of 0 to 2 angstroms per year. High-energy fission of lead, induced by galactic cosmicray protons and alpha particles, has also been observed.