Extralunar Dust in Apollo Cores?

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Science  29 Jan 1971:
Vol. 171, Issue 3969, pp. 372-374
DOI: 10.1126/science.171.3969.372


Densities of nuclear tracks exceed 1011 per square centimeter in several percent of the micrometer-size silicate grains from all depths in the 12-and 60-centimeter lunar cores. Either these grains were irradiated in space as extralunar dust or the ratio of iron to hydrogen in low-energy (about 1 million electron volts per nucleon) solar particles is orders of magnitude higher than in the photosphere.

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