Engineering topics
Publications and source records attributed to Lightner, B. D..
Evidence is presented for the presence in Apollo 16 light matrix breccias of trapped xenon which is isotopically similar to terrestrial xenon. This trapped component is predominantly released above 900 C, together with cosmic ray produced spallation gases. The relative abundances of Ar, Kr, and Xe are distinct from both solar and terrestrial patterns. Terrestrial-type xenon has so far been observed in both Apollo 14 and 16 breccias.
The evidence for in situ produced fission xenon from Pu-244 in rock 14321 is presented. The inferred abundance ratio Pu-244/U-238 is found to be consistent with values observed in a meteorite. Data from a stepwise release of the xenon permits a characterization of the trapped component, which can be shown to be distinct from solar xenon. We discuss the evidence for the presence of fission gases and of uncorrelated radiogenic argon in this and in other Apollo 14 rocks and some implications regarding their origin.
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The results obtained from mass-spectrometry analyses of the noble gases He, Ne, Ar, Kr, and Xe in a 182-mg chip of the largest Apollo 15 rock 15555 are presented. The spallation krypton data indicate a well-shielded location through most of the time during which the rock was exposed to cosmic rays. Gas retention ages are estimated. No evidence for the presence of products from plutonium-244 or iodine-129 was found.