Laboratory measurements of D/H ratios in interplanetary dust

Abstract

Measurements of noble gas elemental and isotopic abundance patterns have provided evidence that a subset of the particles collected in the upper atmosphere by NASA aircraft are micrometeorites. This ‘chondritic’ subset is characterized by major and trace element contents within a factor of 2 of cosmic abundances¹. We have found that the deuterium in two such particles is enriched relative to hydrogen by 500–1,100‰ when compared with the terrestrial SMOW standard. This result confirms the extraterrestrial origin of the ‘chondritic’ dust particles and demonstrates that the material preserves an interesting, and potentially unique, isotopic record which may reflect a memory of processes occurring during (or before) the formation of the Solar System. In addition, the deuterium enrichment seen in the interplanetary dust particles is analogous to that observed in bulk samples of one carbonaceous meteorite and two unequilibrated ordinary chondrites as well as in chemical separates of a number of other meteorites. In this sense interplanetary dust is also ‘primitive’ material.